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Dokumentenidentifikation EP1036870 26.10.2000
EP-Veröffentlichungsnummer 1036870
Titel Fehlererkennungsvorrichtung für Schaftmaschine
Anmelder Murata Kikai K.K., Kyoto, JP
Erfinder Yamauchi, Toshio, Kyoto-shi, Kyoto, JP;
Sone, Yoshifuto, Moriyama-shi, Shiga, JP
Vertreter derzeit kein Vertreter bestellt
Vertragsstaaten AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LI, LU, MC, NL, PT, SE
Sprache des Dokument EN
EP-Anmeldetag 21.12.1999
EP-Aktenzeichen 991255738
EP-Offenlegungsdatum 20.09.2000
Veröffentlichungstag im Patentblatt 26.10.2000
IPC-Hauptklasse D03D 51/46

Beschreibung[en]
Field of the Invention

The present invention relates to a device that is used when an actuator is driven based on an instruction from a central control device as in the manufacture of fabrics using a dobby machine and that detects an error in the actuator or an element of its drive circuit based on a signal output from the central control device to the drive circuit and an input signal to the central control device via the drive circuit.

Background of the Invention

In a weaving machine, a desired weave pattern can be obtained by selectively elevating or lowering a plurality of held frames to open warps according to the weave pattern. Each held frames is elevated and lowered by selectively oscillating a jack lever of a dobby machine connected to a wire on the held frame. The jack lever is oscillated by engaging or disengaging a hook in an oscillating mechanism of the jack lever and turning on or off power transmitted between the jack lever and an oscillation drive source (according to the present invention, a fluid cylinder is used as an actuator) of the jack lever. In addition, the power transmitted between the fluid cylinder and the jack lever is turned on and off by turning on and off a magnetic valve that controls the supply of a pressurized fluid to the fluid cylinder.

Since, the dobby machine performs continuous operations for repeating the elevation and lowering of the held frames 600 times or more per minute on the average, the malfunction occurrence rate must be minimized. An example technique for achieving this object is described in Unexamined Japanese Patent Application Publication (Tokkai-hei) Number 8-109537. According to the technique described in this publication, a sensor for detecting the wire of the held frame is provided at a position at which the wire is located after it is drawn by the oscillating jack lever, and a signal from this sensor and a pattern signal output from a computer to operate the magnetic valve of the fluid cylinder are compared together to determine whether the jack lever is operating correctly, thereby preventing malfunctions.

However, it is difficult to accurately detect the movement of an oscillating section of the jack lever by using the technique described in the publication due to vibration caused by fast operations. Consequently, if there are any problems in a control circuit of the fluid cylinder used as the actuator for driving the jack lever, the jack lever will malfunction and make defective fabrics. The causes of such a failure in the actuator control system may include a failure in a short-circuit or open mode of the magnetic valve, a contact failure or slip-out of a connector connecting the magnetic valve and the drive circuit, damage to an element in the drive circuit (a short circuit or an open circuit), and damage to or malfunction of an output port of a computer outputting instructions to the drive circuit.

Summary of the Invention

The present invention has eliminated these problems. Its object is to prevent an actuator from malfunctioning by comparing a signal output from a central control device to a drive circuit with a signal input to the central control device via the drive circuit.

The means adopted by the present invention to achieve this object is an actuator-driving error detection device characterized to include detection means for detecting an error based on the state of an output signal from the central control device to the drive circuit and the state of a signal input to the central control device via the drive circuit.

The state of the signal output from the central control device can be compared with the state of the signal input to the central control device to detect an error in an element or a load within the actuator drive circuit. Thus, by simply processing the input signal to the central control device via the drive circuit and the output signal from the central control device to the drive circuit, whether the driving carried out by actuator is normal can be detected accurately.

The means adopted by the present invention to achieve this object is an actuator-driving error detection device wherein the error detection means stores the state of the output signal from the central control device to the drive circuit at a specified point of time to determine whether an error is occurring based on a combination of the state of a signal input to the central control device from the drive circuit at a point of time corresponding to the specified point of time with the state of the stored output signal.

By comparing together the states of the input and output signals at the specified point of time, the central control device can determine whether there is an error at the specified point of time.

Furthermore, the means adopted by the present invention to achieve this object is an actuator-driving error detection device wherein the drive circuit includes an input section for receiving a signal from an output port of the central control device, a drive section for switching a load on and off according to an operation of the input section, an output section for outputting a signal to an input port of the central control device, a voltage dependent element operating according to a potential at an intermediate point between the drive section and the load, and a switch element provided between the voltage dependent element and the output section, and switched on and off according to the operational state of the voltage dependent element.

In this manner, the drive circuit includes the voltage dependent element operating according to the potential at the intermediate point between the drive section and the load, and the switch element provided between the voltage dependent element and the output section and switched on and off according to the operational state of the voltage dependent element. Accordingly, if the load fails in the short-circuit or open mode, the state of the potential at the intermediate point can be accurately transmitted to an output section via the switch element.

Brief Description of the Drawing

Figure 1 is a circuit diagram of a control circuit of a device according to one embodiment of the present invention.

Figure 2 is a block diagram of the control circuit of the device according to the embodiment of the present invention.

Detailed Description of the Preferred Embodiments

A configuration of the present invention will be described below based on the embodiment of the present invention shown in the drawings.

This embodiment will be explained in conjunction with an actuator-driving error detection device in a dobby machine provided with a jack lever for drawing a wire connected to a held frame of a weaving machine and an actuator for oscillating a leading lever in an oscillating mechanism of the jack lever. This dobby machine performs continuous operations for repeating the elevation and lowering of the held frames 600 times or more per minute on the average, this machine may be subjected to large vibration. In addition, since actuator operation signals are frequently turned on and off at short cycles, detection of errors in actuator driving is particularly important. According to this embodiment, a load driven by a drive circuit is a magnetic valve, and the actuator is a fluid cylinder controlled by the magnetic valve. However, a load such as a solenoid that is used as the actuator may be driven by the drive circuit.

Figures 1 and 2 show one embodiment of the present invention in which the actuator is a fluid cylinder for driving the jack lever of the dobby machine.

Figure 1 is a circuit diagram of a control circuit, and Figure 2 is a block diagram of the control circuit.

As shown in Figure 2, a control circuit for driving a jack lever is provided with a drive circuit 2 controlled by an output signal from a central control circuit 1 to turn on and off a magnetic valve (a load) that controls a fluid cylinder for driving the jack lever (an actuator). The drive circuit 2 is adapted to feed back the state of the magnetic valve 3 to the central control device 1. In Figure 2, 4 is an output port through which an operation signal is output from the central control device 1 to a driver 2, and 5 is an input port through which a state signal is input to the central control device 1 from the driver 2. The central control device 1 has connected thereto a ROM program 6 for driving and controlling the weaving machine and a RAM 7, a memory card 8, and a floppy disc 9 all used to input pattern data on fabrics.

Figure 1 shows an electric circuit for communicating data between the central control device 1 and the drive circuit 2. As shown in Figure 1, a control signal (a) output from the central control device 1 is input to the drive circuit 4 through the output port 4. In this case, the central control device 1 requires + 5 volts, whereas the drive circuit requires + 24 volts, so the control signal (a) input to the drive circuit 2 through the output port 4 is electrically connected to an input-side photocoupler (an input section) 10 comprising a light-emitting diode (a projector) 10a and a phototransistor (a light receiving device) 10b. An emitter side (reference character (b) shown in Figure 1) of the phototransistor 10b is connected to a base side of Q1 of two-stage amplifying transistors Q1, Q2. A magnetic valve 3 for controlling the fluid cylinder for driving a jack lever is connected to a collector side of the two-stage amplifying transistors Q1, Q2, and a diode 11 is connected to the magnetic valve 3 in parallel to protect it.

In addition, a base side and resistor R3 side of a transistor Q3 are connected to an emitter side of the output transistor Q2 in order to detect an overcurrent and so that if an overcurrent flows, the transistor Q3 instantaneously operates to reduce a base current through the transistor Q2 to prevent damage to the transistor Q2. An emitter side of the transistor Q3 is grounded, and its collector side is connected at an intermediate point between the emitter side of the phototransistor 10b and the base side of the transistor Q1.

Furthermore, the collector side (reference character (c) shown in Figure 1) of the output transistors Q1 and Q2 is grounded via a series connection between resistors R1, R2 and a Zener diode 12 that is a voltage dependent element turned on and off depending on an inter-terminal voltage. A base side of a failure-detecting transistor Q4 that is turned on and off when the Zener diode 12 is turned on and off is connected at an intermediate position between the resistors R1, R2. That is, when the potential at point (c) increases above a predetermined value to generate a voltage of a predetermined value or higher between the terminals of the Zener diode 12, a current flows through the Zener diode 12 to turn the transistor Q4 on. A collector side (reference character (d) shown in Figure 1) of the transistor Q4 is connected to a + 24 volts power supply side via a light emitting diode 13a of an output side photocoupler (an output section 13). A + 5 volts power voltage is applied to a collector side of a phototransistor 13b that is a light receiving side of the photocoupler 13, and the collector side is connected to the central control device 1 via the input port 5.

Next, an operational aspect of the error detection device configured as described above will be described.

First, the case will be described in which the magnetic valve 3 controlling the fluid cylinder for driving the jack lever of the dobby machine operates normally.

In this case, as shown in Figure 1, while a chip select signal Csn (a valid signal) of the output port 4 is valid, the central control device 1 outputs the control signal (a) for turning the magnetic valve 3 on, based on weave pattern data. That is, a signal on a data bus of the central control device 1 is loaded in the output port 4 based on the chip select signal Csn. The control signal (a) is sequentially turned on and off based on weave pattern data.

This ON operation of the control signal (a) is transmitted to the light-receiving-side phototransistor 10b from the light-emitting diode 10a of the photocoupler 10, thereby allowing the phototransistor 10b to perform an ON operation. The output port 4 latches the state of the ON operation of the phototransistor 10b until the next control signal (a) (Hi) is input. Thus, an output signal (a signal at point (b)) of the phototransistor 10b is maintained at a voltage Vc for a predetermined amount of time. Accordingly, the voltage Vc is applied to the base side of the output transistor Q1 to turn the transistor Q1 on. Consequently, the two-stage amplifying transistor Q2 is also turned on to allow a current to flow from the collector side of transistor Q2 to its emitter side. Thus, a current also flows through the magnetic valve 3 to turn it on. This ON operation of the magnetic valve 3 causes a fluid to be supplied to the fluid cylinder to allow the cylinder to project in order to control the jack lever via a known oscillating mechanism.

When the two-stage transistors Q1, Q2 (the drive section that switches the magnetic valve 3 on and off) are on, the voltage at the connection point (c) that is the intermediate point between the drive section and the magnetic valve 3 is at a "Low" level. Accordingly, no current flows through the Zener diode 12, and the output from the transistor Q4 connected to the connection point (c) via the Zener diode 12 remains off. Consequently, the voltage at the connection (d) is at a "Hi" level, and the light-emitting diode 13a directly connected to the connection (d) remains off. At this point, since the light-emitting diode 13a is off, the phototransistor 13b that is a light-receiving device for the light-emitting diode 13a remains off, and the signal (e) input to the central control device 1 through the input port 5 is inverted at the input port 5 to become a "Low" output. In this manner, when the control signal (a) from the central control device 1 is a "Hi" output and the input signal (e) corresponding to this state is a "Low" output, the drive circuit 2 and the magnetic valve 3 can be assumed to be normal.

On the contrary, if the control signal (a) from the central control device 1 is "Low," the photocoupler 10 is turned off to preclude a current from flowing to the base side of the amplifying transistor Q1, thereby maintaining the transistors Q1 and Q2 off. Thus, no current flows through the magnetic valve 3, which thus remains off to prevent the fluid cylinder from projecting (the cylinder is withdrawn). At this point, the voltage at the connection point (c) is at the "Hi" level, so a current flows through the Zener diode 12 to turn the transistor Q4 and the photocoupler 13 on, and the signal (e) input to the central control device 1 is inverted at the input port 5 to become a "Hi" output. In this manner, when the control signal (a) output from the central control device 1 is a "Low" output and the input signal (e) corresponding to this state is a "Hi" output, the drive circuit 2 and the magnetic valve 3 can also be assumed to be normal.

Next, the case will be explained in which a short circuit occurs between the transistor Q2 and the power supply or in which the magnetic valve 3 fails in a short circuit mode. Even with such a short circuit accident, if the control signal (a) from the central control device 1 is "Low," the potential at point (c)is "Hi" and the input signal (e) to the central control device 1 is the same as in the normal state. When, however, the control signal (a) becomes "Hi," an excessive short-circuit current instantaneously flows from the collector of the transistor Q2 to its emitter. If this short-circuit current continues flowing for several seconds, the transistor Q2 is destroyed due to its tolerable power.

Thus, in order to prevent above problem, the circuit in Figure 1 includes a short-circuit protect circuit (a current limitation circuit) including the transistor Q3 and the resistor 3. In this circuit, a predetermined voltage defined by the resistance value of the resistor R3 and the value of a current flowing through the resistor R3 is applied to the base side of the transistor Q3. If a short-circuit current larger than in the normal state flows from the collector of the transistor Q2 to its emitter, the voltage across the resistor R3, that is, the base voltage of the transistor Q3 increases to turn the transistor Q3 on. Thus, a base current of the transistor Q1 (a collector current of the phototransistor 10b) is bypassed as a collector current of the transistor Q3 to reduce the base voltage applied to the transistor Q1. Accordingly, the base current and the collector current flowing through the transistor Q1 decrease and then the collector current through the transistor Q2 decreases to protect the transistor Q2.

Such a current limitation action defines the potential at point (c) at a predetermined value depending on the constants and characteristics of each element. If a short circuit accident such as that described above occurs, this current limitation action reduces the collector current of the transistor Q2 to increase the potential at point (c) until the Zener diode 12 can be turned on. Consequently, despite the "Hi" state of the control signal (a), the transistor Q4 is turned on and the input signal (e) to the central control device 1 becomes "Hi," so an error can be determined.

If, however, this state lasts over a long period of time, heat generated in the transistor Q2 may damage the transistors Q1, Q2. Thus, upon detecting the error, the central control device 1 immediately stops the weaving machine while returning the control signal (a) at the output port 4 to "Low." At this point, a display device (not shown in the drawings) can display an error as well as its possible cause.

In this manner, this device comprises the short-circuit protect circuit for restraining an excessive current from flowing through the drive section, and the detection circuit located at the output side (point (c)) of the drive section including the voltage dependent element (the Zener diode 12) and the switch element (the transistor Q4). As a result, if a short-circuit accident such as that described above occurs, the switch elements (the transistors Q1, Q2) of the drive section can be protected and this short-circuit can be detected based on an output from the detection circuit.

In addition, if the magnetic valve 3 fails in an open mode and if the control signal (a) from the central control device 1 is "Low," the photocoupler 10 is off, so the two-stage amplifying transistors Q1, Q2 remain off. In the normal state, when the transistors Q1, Q2 are off, the potential at connection point (c) is "Hi." Since the magnetic valve 3 connected to the collector side of the transistors Q1, Q2 is in the open mode, the voltage level of the connection point (c) is close to 0 volt despite the OFF state of the transistors Q1, Q2, so no current flows through the Zener diode 12 and the transistor Q4 remains off. Accordingly, the light-emitting diode 13a and the phototransistor 13b are off, and the inverted signal (e) input to the central control device 1 through the input port 5 is "Low". In this manner, if the control signal (a) from the central control device 1 is "Low" and the corresponding input signal (e) is "Low," it is determined as an error. A possible cause of this error can be assumed to the open mode of the magnetic valve 3. If a short circuit occurs in the transistor Q1 or Q2, a relationship between the control signal (a) and the input signal (e) becomes similar to that described above. Of course, if such an error occurs, the weaving machine is immediately stopped as described above. In this case, the display device (not shown in the drawings) can display an error as well as its possible cause.

In this manner, a detection circuit is arranged between the output side (point (c)) of the drive section and the output section (the output-side photocoupler 13). The detection circuit includs the voltage dependent element (the Zener diode 12) and the switch element (the transistor Q4) that is turned on and off depending on the operation of the voltage dependent element. As a result, even if the load fails in the open mode, this error can be accurately detected from the control signal (a) and the input signal (e).

In summary, this embodiment can promptly and accurately detect an error in driving carried out by the actuator to oscillate the leading lever of the dobby machine without the use of a special sensor for detecting the movement of a movable member within the jack lever oscillating mechanism. Upon detecting an error, the embodiment can immediately stop the weaving machine to minimize the number of unacceptable fabrics.

This embodiment has been described in conjunction with the one magnetic valve 3 controlling the fluid cylinder for oscillating the jack lever used for the dobby machine. An actual dobby machine, however, has, for example, 16 similar magnetic valves 3 corresponding to an upper frame and 16 magnetic valves 3 corresponding to a lower frame, wherein the input port 4, the output port 5 and the drive circuit 2 and so on are arranged to individually control these plurality of magnetic valves 3.

As described above, the present invention includes the detection means for detecting an error based on the state of the output signal from the central control device to the drive circuit and the state of the signal input to the central control device via the drive circuit. Thus, the states of these input and output signals can be compared together to detect an error in an element or a load within the drive circuit. Thus, by simply processing the signal input to the central control device via the drive circuit and the signal output from the central control device to the drive circuit, it accurately determines whether the driving carried out by actuator is normal.

In addition, according to the present invention, the error detection means stores the state of the output signal from the central control device to the drive circuit at a specified point of time to determine whether an error occurs based on a combination of the state of the signal input to the central control device at a point of time corresponding to the specified point of time with the state of the stored output signal. Consequently, the central control device can determine whether there is an error at the specified point of time.

Furthermore, the drive circuit according to the present invention includes the input section for receiving a signal from the output port of the central control device, the drive section for switching the load on and off according to an operation of the input section, the output section for outputting a signal to the input port of the central control device, the voltage dependent element operating according to the potential at the intermediate point between the drive section and the load, and the switch element provided between the voltage dependent element and the output position and switched on and off according to the operational state of the voltage dependent element. Accordingly, if the load fails in the short-circuit or open mode, the state of the potential at the intermediate point can be accurately transmitted to an output section to detect the failure in the load in the short-circuit or open mode.


Anspruch[en]
  1. In a dobby machine driving device comprising an actuator for selectively elevating or lowering a held frame of a weaving machine, a central control device, and a drive circuit for activating said actuator based on an output signal from the central control device, a dobby machine driving error detection device characterized to include a detection means for detecting an error based on the state of said output signal and the state of a signal input to the central control device via the drive circuit.
  2. A dobby machine driving error detection device as in Claim 1 characterized in that said error detection means stores the state of said output signal at a specified point of time to determine whether an error is occurring based on a combination of the state of a signal input to the central control device from the driving circuit at a point of time corresponding to said specified point of time with the state of said stored output signal.
  3. A dobby machine driving error detection device as in Claim 2 characterized in that said drive circuit includes an input section for receiving a signal from an output port of the central control device, a drive section for switching a load on and off according to an operation of the input section, an output section for outputting a signal to an input port of the central control device, a voltage dependent element operating according to a potential at an intermediate point between said drive section and said load, and a switch element provided between the voltage dependent element and said output section, and switched on and off according to the operational state of the voltage dependent element.
  4. A dobby machine driving error detection device as in Claim 3 characterized in that said drive circuit includes a short-circuit protection circuit for limiting a current flowing through the drive section if a short circuit occurs between the drive section and a power supply side or if the load becomes defective in a short-circuit mode.
  5. A dobby machine driving error detection device as in any one of Claims 2 to 4 characterized in that the error detection device comprises a display device to display a possible cause of an error identified based on a combination of the state of a signal input to the central control device from the drive circuit at the point of time corresponding to said specified point of time with the state of said stored output signal.






IPC
A Täglicher Lebensbedarf
B Arbeitsverfahren; Transportieren
C Chemie; Hüttenwesen
D Textilien; Papier
E Bauwesen; Erdbohren; Bergbau
F Maschinenbau; Beleuchtung; Heizung; Waffen; Sprengen
G Physik
H Elektrotechnik

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