Electromagnetic valve system

In a control unit of an electromagnetic valve system, a safety circuit includes a first switch and a second switch for switching, by control from a control circuit supply and shutdown of power from a drive power supply to an electromagnetic valve drive circuit. A common line extends to a plurality of electromagnetic valve units and is connected to one end of a plurality of solenoids. A plurality of power lines are connected to the other end of each of the plurality of solenoids. The electromagnetic valve drive circuit includes a plurality of open/close switches for switching, by control from the control circuit, supply and shutdown of power to the plurality of solenoids.

TECHNICAL FIELD

The present invention relates to a solenoid valve system (electromagnetic valve system) including a control unit and a plurality of solenoid valve units arranged in a row with respect to the control unit.

BACKGROUND ART

U.S. Pat. No. 8,156,965 discloses a solenoid valve system in which a plurality of solenoid valve units are arranged in a row with respect to a control unit. In this solenoid valve system, control/sensor lines (control lines) run from the control unit to the plurality of solenoid valve units. Further, voltage supply lines (power lines, power-supply lines) run through the plurality of solenoid valve units. With this configuration, the solenoid valves in the plurality of solenoid valve units can be driven by supplying control signals to the plurality of solenoid valve units from the control unit through the control/sensor lines, while electric power is being supplied to the plurality of solenoid valve units through the voltage supply lines.

SUMMARY OF INVENTION

However, in the solenoid valve system, since the control/sensor lines and the voltage supply lines run inside the plurality of solenoid valve units, the control/sensor lines and the voltage supply lines may be short-circuited in the solenoid valve units.

The present invention has been devised considering such a problem, and an object of the invention is to provide a solenoid valve system that avoids short circuiting between control lines and power-supply lines in solenoid valve units.

An aspect of the invention is directed to a solenoid valve system including: a control unit; and a plurality of solenoid valve units that are arranged in a row with respect to the control unit, the plurality of solenoid valve units including solenoids configured to drive solenoid valves by supply of electric power from the control unit.

The control unit includes a safety circuit connected to a driving power supply provided externally, a solenoid valve drive circuit having an input side connected to the safety circuit and an output side connected to the plurality of solenoid valve units, and a control circuit configured to control the safety circuit and the solenoid valve drive circuit. In this case, the safety circuit includes a first switching portion configured to switch supply and shutoff of electric power from the driving power supply to the solenoid valve drive circuit, by being controlled by the control circuit.

The solenoid valve system further includes a single common line connected to one terminal of the driving power supply through the safety circuit, and extending to the plurality of solenoid valve units and connected to one end of each of the plurality of solenoids, and a plurality of power lines connected to another terminal of the driving power supply through the safety circuit and connected respectively to other ends of the plurality of solenoids. The solenoid valve drive circuit includes a plurality of second switching portions provided respectively on the plurality of power lines and configured to switch supply and shutoff of electric power from the safety circuit to the plurality of solenoids, by being controlled by the control circuit.

According to the invention, the control unit only performs power supply to the solenoids of the plurality of solenoid valve units through the common line and the power lines that are power-supply lines. That is, according to the invention, control signals are sent and received between the control circuit, and the safety circuit and solenoid valve drive circuit within the control unit, and therefore no control line for supplying control signals is provided in the plurality of solenoid valve units. As a result, it is possible to avoid short circuiting between control lines and power-supply lines in the solenoid valve units, which might occur in the technique disclosed in U.S. Pat. No. 8,156,965.

Furthermore, the first switching portion provides an interlock control on the solenoid valve drive circuit and the plurality of solenoid valve units, and the second switching portions achieve supply and shutoff of electric power to the individual solenoids. This enables the interlock control and the driving of the solenoid valves to be carried out efficiently.

Moreover, the entire solenoid valve system can be downsized because the control circuit, the safety circuit, and the solenoid valve drive circuit are contained within the control unit.

DESCRIPTION OF EMBODIMENTS

Preferred embodiments of the solenoid valve system according to the present invention will be described in detail below while referring to the accompanying drawings.

[1. Schematic Configuration of Solenoid Valve System10]

As shown inFIG. 1, a solenoid valve system10of an embodiment includes a control unit12and a plurality of solenoid valve units14. The plurality of solenoid valve units14are arranged in a row with respect to the control unit12.

The control unit12includes a control circuit16, a safety circuit18, a solenoid valve drive circuit20, and a solenoid valve connection portion22.

The control circuit16is connected to a controlling power supply24as an external dc power source and also to a sequencer28as a host device such as a PLC (Programmable Logic Controller) etc. through fieldbus26. The control circuit16is also connected to the safety circuit18and the solenoid valve drive circuit20through control lines30,32, respectively.

The safety circuit18, the solenoid valve drive circuit20, and the solenoid valve connection portion22are provided in the control unit12for the purpose of supplying electric power to the plurality of solenoid valve units14from a driving power supply34as an external dc power source. In this case, the safety circuit18, the solenoid valve drive circuit20, the solenoid valve connection portion22, and the plurality of solenoid valve units14are connected in this order in parallel with the driving power supply34.

The safety circuit18includes a first switch (first switching portion)36, a second switch (first switching portion)38, and a safety control circuit40. The first switch36is disposed on a single positive-side power line (common line)42that extends from a positive-side terminal (one terminal) of the driving power supply34to the plurality of solenoid valve units14. The second switch38has its one end connected to a negative-side terminal (the other terminal) of the driving power supply34and its other end connected to a single negative-side power line44. The safety control circuit40turns on/off the first switch36and the second switch38that serve as shutoff switches, based on a control signal supplied from the control circuit16through the control line30.

The solenoid valve drive circuit20includes a plurality of open/close switches (second switching portions)46. In the solenoid valve drive circuit20, the same number of negative-side power lines50(power lines) as the plurality of solenoid valve units14branch off from a common terminal48of the single negative-side power line44connected to the second switch38. The plurality of branching negative-side power lines50extend to the corresponding solenoid valve units14, respectively. The plurality of open/close switches46are disposed respectively on the plurality of negative-side power lines50and turn on and off based on a control signal supplied from the control circuit16through the control line32.

The number of the negative-side power lines50mentioned above is merely an example, and a larger number of negative-side power lines50than the plurality of solenoid valve units14may branch from the common terminal48. It is then possible to easily deal with a situation where the number of the plurality of solenoid valve units14connected to the control unit12is increased or decreased. That is, a negative-side power line50not extending to any solenoid valve unit14serves as a standby power line for a newly connected solenoid valve unit14. Two or more negative-side power lines50may run into a single solenoid valve unit14. Further, if a solenoid valve unit14having no solenoid valve is connected to the control unit12, a given number of negative-side power line(s)50may run in that solenoid valve unit14.

The first switch36, the second switch38, and the plurality of open/close switches46can be any switching unit that turn on and off based on supply of control signals. Such switching unit includes semiconductor switching devices such as transistors etc., for example. If the positive-side power line42is a common line as shown inFIG. 1, then a PNP transistor may be used as the first switch36, and NPN transistors may be used as the second switch38and the plurality of open/close switches46, for example.

The solenoid valve connection portion22is a connecting unit such as a connector etc., through which the single positive-side power line42and the plurality of negative-side power lines50pass and which connects the control unit12and the plurality of solenoid valve units14electrically.

Each of the plurality of solenoid valve units14includes a solenoid52for driving a solenoid valve not shown. The plurality of solenoids52each have its positive-side terminal (one end) connected to the positive-side power line42. The plurality of solenoids52each have its negative-side terminal (the other end) connected to a corresponding one of the negative-side power lines50.

Since the plurality of solenoid valve units14are arranged in a row as stated above, the positive-side power line42extends from the positive-side terminal of the driving power supply34to the solenoid valve unit14that is most distant from the driving power supply34. Also, each of the plurality of negative-side power lines50extends to a corresponding one of the solenoid valve units14and is connected to the negative-side terminal of the solenoid52.FIG. 1illustrates an example in which one solenoid valve unit14includes one solenoid52, but one solenoid valve unit14may include two or more solenoids52.

[2. Schematic Operations of Solenoid Valve System10]

Next, operations of the solenoid valve system10of the embodiment will be described.

First, when electric power is being supplied to the control circuit16from the controlling power supply24and so the control circuit16is in operation, an instruction signal is supplied to the control circuit16from the sequencer28through the fieldbus26. In this case, the instruction signal can be a signal that designates driving of any of the solenoid valves, for example.

Upon receiving the instruction signal, the control circuit16supplies control signals (“on” signal or “off” signal), based on the instruction signal, to the safety circuit18and the solenoid valve drive circuit20respectively through the control lines30,32.

Upon receiving an on signal through the control line30, the safety control circuit40in the safety circuit18turns on the first switch36and the second switch38on the basis of the on signal. Further, the solenoid valve drive circuit20receives the on signal through the control line32and then the corresponding open/close switch46turns on. That is, the first switch36, the second switch38, and the open/close switches46are normally kept in an off state by an off signal that is supplied to the safety circuit18and the solenoid valve drive circuit20from the control circuit16, and are brought into an on state from the off state by the supply of the on signal.

Then, the positive-side terminal of the driving power supply34is electrically connected to the positive-side terminals of the solenoids52of the plurality of solenoid valve units14through the first switch36and the positive-side power line42. On the other hand, the negative-side terminal of the driving power supply34is electrically connected to, among the plurality of solenoid valve units14, the negative-side terminal of the solenoid52that is connected to the open/close switch46that has been brought into the on state, through the second switch38, the negative-side power line44, the open/close switch46, and the corresponding negative-side power line50. This allows the driving power supply34to supply electric power to the electrically connected solenoid52through the safety circuit18, the solenoid valve drive circuit20, and the solenoid valve connection portion22, i.e., through the positive-side power line42and the negative-side power lines44,50. As a result, the solenoid52supplied with electric power is excited to drive the solenoid valve corresponding to that solenoid52.

In this way, when the solenoid valves of all solenoid valve units14are to be actuated, the first switch36and the second switch38are turned on and all open/close switches46are turned on, to thereby supply electric power to all solenoids52from the driving power supply34. When only some of the solenoid valves are to be actuated, the first switch36and the second switch38are turned on, and the open/close switches46connected to the solenoids52of those solenoid valves are turned on, to thereby supply electric power to those solenoids52from the driving power supply34.

During operation of the solenoid valve system10, the control circuit16may notify the sequencer28through the fieldbus26about operating conditions of the safety circuit18and the solenoid valve drive circuit20, i.e., driving conditions of the solenoid valves constituting the solenoid valve units14.

When the control signal supplied to the solenoid valve drive circuit20from the control circuit16through the control line32changes from on signal to off signal, then the open/close switches46turn off. Then, the supply of electric power from the driving power supply34to the solenoids52stops, whereby driving of the solenoid valves including those solenoids52can be stopped.

Further, when the control signal supplied to the safety circuit18from the control circuit16through the control line30changes from on signal to off signal, then the first switch36and the second switch38turn off. It is thus possible to suitably perform an interlock control on the solenoid valve drive circuit20and the plurality of solenoid valve units14, in cases of an abnormality of the controlling power supply24or the driving power supply34(voltage lowering) or a fault in the control unit12(a fault of the control circuit16).

[3. Detailed Configuration of Control Unit12]

Schematic configuration and schematic operations of the solenoid valve system10of the embodiment are as described above. Next, a detailed configuration in the control unit12will be described referring toFIG. 2.

When the controlling power supply24and the driving power supply34are dc power sources with the same output voltage, the control unit12may further include a downconverter54, such as a DC/DC converter etc. Then, the downconverter54can lower the dc voltage output from the controlling power supply24to the driving voltage of the control circuit16and supply the lowered voltage to the control circuit16. This is because, in the control unit12, a power-supply circuitry56including the safety circuit18, the solenoid valve drive circuit20, and the solenoid valve connection portion22, and a control circuitry58including the control circuit16, operate at voltages with different magnitudes. It is therefore desirable to, in the control unit12, electrically insulate the control circuitry58and the power-supply circuitry56with an insulating circuit not shown.

The safety control circuit40further has a function of performing diagnostic testing of the control unit12. In order to perform the diagnostic testing, the safety control circuit40includes a first microcomputer (first controller)40a, a first diagnosis circuit40b, a second microcomputer (second controller)40c, and a second diagnosis circuit40d.

The first microcomputer40aturns on and off the first switch36, based on the control signal (on signal or off signal) supplied from the control circuit16through the control line30. The first diagnosis circuit40bdiagnoses the state of the positive-side power line42when the first switch36is turned on/off. The second microcomputer40cturns on and off the second switch38, based on the control signal supplied from the control circuit16through the control line30. The second diagnosis circuit40ddiagnoses the state of the negative-side power lines44,50when the second switch38is turned on/off. Specifically, the safety control circuit40performs a known pulse test to determine, for example, whether the positive-side power line42and the negative-side power lines44,50are short-circuited with other wiring.

In the pulse test, when the first switch36and the second switch38are in the on state, the first microcomputer40aturns off the first switch36for a given time, or the second microcomputer40cturns off the second switch38for a given time. The first diagnosis circuit40bdetects how the potential of the positive-side power line42varies in the given time. The second diagnosis circuit40ddetects how the potential of the negative-side power lines44,50varies in the given time.

Then, based on the change with time of the potential of the positive-side power line42, the first diagnosis circuit40bdetermines whether the positive-side power line42is short-circuited with other wiring (e.g., with the control lines30,32), or whether the first switch36has a fault such as sticking, and then the first diagnosis circuit40bsends the diagnosis to the second microcomputer40c. Further, based on the change with time of the potential of the negative-side power lines44,50, the second diagnosis circuit40ddetermines whether the negative-side power lines44,50are short-circuited with other wiring (e.g., with the control lines30,32), or whether the second switch38has a fault such as sticking, and then the second diagnosis circuit40dsends the diagnosis to the first microcomputer40a.

For example, after the first switch36was turned off, if the potential of the positive-side power line42promptly lowers to a given potential, e.g., zero potential etc., within a given time period, then the first diagnosis circuit40bdetermines that there is no fault of the first switch36or no short circuit between the positive-side power line42and other wiring. If, after the first switch36was turned off, the potential of the positive-side power line42slowly lowers as time passes, then the first diagnosis circuit40bdetermines that the potential is lowering slowly due to the capacitor component of the positive-side power line42etc. Further, if the lowering of the potential of the positive-side power line42is only slight after the first switch36was turned off, then the first diagnosis circuit40bdetermines that the positive-side power line42is short-circuited with other wiring or the first switch36is faulty.

On the other hand, after the second switch38was turned off, if the absolute value of the potential of the negative-side power lines44,50promptly rises from zero potential to a given potential within a given time period, then the second diagnosis circuit40ddetermines that there is no fault of the second switch38or no short circuit between the negative-side power lines44,50and other wiring. If, after the second switch38was turned off, the absolute value of the potential of the negative-side power lines44,50slowly rises from zero potential as time passes, then the second diagnosis circuit40ddetermines that the potential is rising slowly due to the capacitor component of the negative-side power lines44,50etc. Further, if the rise of the absolute value of the potential of the negative-side power lines44,50is only slight after the second switch38was turned off, then the second diagnosis circuit40ddetermines that the negative-side power lines44,50are short-circuited with other wiring or the second switch38is faulty.

The second microcomputer40csends, to the first microcomputer40a, the diagnosis from the first diagnosis circuit40b, and also sends the diagnosis to the control circuit16through the control line30. Then, if the diagnosis indicates that the positive-side power line42is short-circuited, for example, the first microcomputer40aturns off the first switch36. Also, the second microcomputer40cturns off the second switch38. The first switch36might be sticking, for example, and the power supply from the driving power supply34can be certainly shut off by turning off the second switch38.

On the other hand, the first microcomputer40asends, to the second microcomputer40c, the diagnosis from the second diagnosis circuit40d, and also sends the diagnosis to the control circuit16through the control line30. Then, if the diagnosis indicates that the negative-side power lines44,50are short-circuited, for example, the second microcomputer40cturns off the second switch38. Also, the first microcomputer40aturns off the first switch36. The second switch38might be sticking, for example, and the power supply from the driving power supply34can be certainly shut off by turning off the first switch36.

In this way, in the configuration ofFIG. 2, the first microcomputer40aand the second microcomputer40ccan check the operating conditions with each other by exchanging the diagnosis made by the first diagnosis circuit40band the diagnosis made by the second diagnosis circuit40d. As a result, it is also possible that, if one of the microcomputers has a fault, the other microcomputer can control the first switch36and the second switch38.

The control circuit16receives the diagnosis of short circuit or fault through the control line30, and sends the diagnosis to the sequencer28through the fieldbus26. Then, the sequencer28notifies the user of the occurrence of short circuit or fault, whereby the user can take measures, such as maintenance/replacement etc., of the target component in the control unit12.

The description above has illustrated short circuiting with other wiring, and a fault such as sticking of the first switch36or the second switch38. The safety control circuit40can be configured to perform diagnosis for, for example, an abnormality of the first microcomputer40aor the second microcomputer40c, an abnormality of the first diagnosis circuit40bor the second diagnosis circuit40d, and a situation where the plurality of solenoid valve units14are supplied with power from the driving power supply34even when the first switch36or the second switch38is turned off. Further, the safety control circuit40may be configured also to perform diagnosis for abnormal voltage of the controlling power supply24or the driving power supply34, abnormal internal temperature in the control unit12, and abnormal signal level of the control signals supplied from the control circuit16.

[4. Modifications of Solenoid Valve System10]

Next, modifications (first to third modifications) of the solenoid valve system10of the embodiment will be described referring toFIGS. 3 to 5. In the first to third modifications, the same constituent components as those of the solenoid valve system10ofFIGS. 1 and 2will be labeled with the same reference numerals and will not be described in detail again.

FIG. 3is a schematic configuration diagram of a solenoid valve system10A of a first modification. The first modification differs from the solenoid valve system10ofFIGS. 1 and 2in that the control unit12includes an input circuit62that outputs signals, information, etc. input from external devices60to the control circuit16and that an external connection unit66connectable to a solenoid64of an external solenoid valve is interposed between the solenoid valve connection portion22and the plurality of solenoid valve units14.

The external devices60can be general sensors and safety devices provided on objects to which the solenoid valve system10A is applied (e.g., a door in a factory). Such sensors or safety devices include automatic switches, pressure sensors, push-button switches, light curtains, and so forth, for example.

The input circuit62includes a diagnosis portion68having a similar function to that of the safety control circuit40and is connected to the control circuit16through a control line70. On the basis of a control signal supplied from the control circuit16through the control line70, the diagnosis portion68connects the input circuit62and the control circuit16, and also diagnoses whether or not the inputs from the external devices60are appropriate signals or information. If an input from the external device60is normal, the diagnosis portion68diagnoses the input as being valid and permits output of the signal or information to the control circuit16. On the other hand, if the input from the external device60is abnormal, for example when the input from the external device60is not at an appropriate level due to a short circuit of wiring that connects the external device60and the input circuit62, then the diagnosis portion68diagnoses the input as being abnormal. Then, the diagnosis portion68sends the diagnosis of abnormal input to the control circuit16and the sequencer28, and prohibits output of the signal or information to the control circuit16.

Further, in the solenoid valve system10A, the positive-side power line42and the plurality of negative-side power lines50extend to the plurality of solenoid valve units14through the external connection unit66. Further, an external connection power line72branching off from the positive-side power line42in the external connection unit66is connected to the positive-side terminal (one end) of the solenoid64. Furthermore, an external connection power line74branches off from the common terminal48of the negative-side power line44and is connected to the negative-side terminal (the other end) of the solenoid64through the solenoid valve drive circuit20, the solenoid valve connection portion22, and the external connection unit66.

In the solenoid valve drive circuit20, an open/close switch76(third switching portion) is disposed on the external connection power line74connected to the negative-side terminal of the solenoid64. Like other open/close switches46, the open/close switch76turns on/off based on the control signal supplied from the control circuit16through the control line32.

Accordingly, the solenoid valve including the external solenoid64can be driven by the supply of electric power to this solenoid64from the driving power supply34, through the safety circuit18, the solenoid valve drive circuit20, the solenoid valve connection portion22, and the external connection unit66.

FIG. 3shows a configuration in which the external connection unit66is provided between the solenoid valve connection portion22and the plurality of solenoid valve units14. In the first modification, the external connection unit66may be provided between the plurality of solenoid valve units14, or the external connection unit66may be provided on the downstream side in the direction in which the plurality of solenoid valve units14are coupled (on the downstream side in the direction away from the driving power supply34).

FIG. 4is a schematic configuration diagram of a solenoid valve system10B according to a second modification. The solenoid valve system10B of the second modification differs from the solenoid valve systems10and10A ofFIGS. 1 to 3in that another solenoid valve unit80independent of the plurality of solenoid valve units14is connected between the solenoid valve connection portion22and the plurality of solenoid valve units14, that a single negative-side power line82is a common line connected to the negative-side terminal (one end) of each of the plurality of solenoids52, and that a plurality of positive-side power lines84are connected respectively to the positive-side terminals (the other ends) of the plurality of solenoids52. Accordingly, note that, in the solenoid valve system10B of the second modification, compared to the solenoid valve systems10and10A ofFIGS. 1 to 3, the relative arrangement and connection of the first switch36, the second switch38, and the plurality of open/close switches46between the driving power supply34and the plurality of solenoids52is exchanged between the positive electrode side and the negative electrode side.

That is, one end of the second switch38is connected to the positive-side terminal (the other terminal) of the driving power supply34, and the other end thereof is connected to a positive-side power line86. Positive-side power lines (power lines)84of the same number as, or a larger number than, the plurality of solenoid valve units14branch off from a common terminal88of the positive-side power line86. Each of the plurality of branching positive-side power lines84is connected, for example to the positive-side terminal of the solenoid52of the corresponding solenoid valve unit14. The open/close switches46are provided on the plurality of positive-side power lines84, respectively.

Another positive-side power line (another power line)90is connected to the one end of the second switch38, i.e., to the positive-side terminal of the driving power supply34. The other positive-side power line90extends to the other solenoid valve unit80through the safety circuit18, the solenoid valve drive circuit20, and the solenoid valve connection portion22, and is connected to the positive-side terminal of a solenoid92of the solenoid valve constituting the other solenoid valve unit80.

In the safety circuit18, a shutoff switch (fourth switching portion)94is disposed on the other positive-side power line90. Thus, in the second modification, the second switch38and the shutoff switch94are connected in parallel to the positive-side terminal of the driving power supply34. The safety control circuit40turns on/off the shutoff switch94on the basis of the control signal supplied from the control circuit16through the control line30. The solenoid valve system10B, too, can diagnose the state of the control unit12by turning on/off the shutoff switch94.

The single negative-side power line82(common line) extends from the negative-side terminal of the driving power supply34to the other solenoid valve unit80and the plurality of solenoid valve units14, through the safety circuit18, the solenoid valve drive circuit20, and the solenoid valve connection portion22, and is connected to the negative-de terminals of the plurality of solenoids52,92. The first switch36is provided on the negative-side power line82.

Then, in the second modification, the other solenoid valve unit80is a solenoid valve unit whose solenoid valve operates independently of the plurality of solenoid valve units14. The phrase “solenoid valve operates independently of” means that the other solenoid valve can be operated irrespective of whether the second switch38and the plurality of open/close switches46are on or off.

That is, even when the first switch36, the second switch38, and the plurality of open/close switches46are in the on state, only the solenoid valve of the other solenoid valve unit80can be moved to the off position (stopped) by turning off the shutoff switch94to thereby shut off the power supply to the solenoid92of the other solenoid valve unit80from the driving power supply34. The second modification allows solenoid valves, for example a safety exhaust valve used by the object to which the solenoid valve system10B is applied, or other manifold solenoid valves provided externally, to operate as independent solenoid valves.

InFIG. 4, since the negative-side power line82is a common line, PNP transistors, for example, can be used as the plurality of open/close switches46.

FIG. 5is a schematic configuration diagram of a solenoid valve system10C according to a third modification. The third modification differs from the solenoid valve systems10,10A,10B ofFIGS. 1 to 4in that the control unit12is formed of a control module12aconnected to the controlling power supply24and the driving power supply34, and an output module12bcoupled to the plurality of solenoid valve units14. In this case, the control module12aincludes the control circuit16. The output module12bincludes the safety circuit18, the solenoid valve drive circuit20, and the solenoid valve connection portion22.

[5. Effects of Embodiments]

As has been described above, the solenoid valve system10,10A to10C of the embodiment includes the control unit12, and the plurality of solenoid valve units14that are arranged in a row with respect to the control unit12. The plurality of solenoid valve units14include solenoids52for driving solenoid valves by electric power supplied from the control unit12.

The control unit12includes the safety circuit18connected to the driving power supply34provided externally, the solenoid valve drive circuit20having its input side connected to the safety circuit18and its output side connected to the plurality of solenoid valve units14, and the control circuit16configured to control the safety circuit18and the solenoid valve drive circuit20. In this case, the safety circuit18includes a first switching portion (the first switch36, the second switch38) for switching supply and shutoff of the electric power from the driving power supply34to the solenoid valve drive circuit20, by being controlled by the control circuit16.

The solenoid valve system10,10A to10C further includes a single common line (the positive-side power line42or the negative-side power line82) connected to one terminal (positive-side terminal or negative-side terminal) of the driving power supply34through the safety circuit18, and extending to the plurality of solenoid valve units14and connected to one end (positive-side terminal or negative-side terminal) of each of the plurality of solenoids52, and a plurality of power lines (the negative-side power lines50or the positive-side power lines84) connected to the other terminal (negative-side terminal or positive-side terminal) of the driving power supply34through the safety circuit18and connected respectively to the other ends (negative-side terminals or positive-side terminals) of the plurality of solenoids52. The solenoid valve drive circuit20includes a plurality of second switching portions (the open/close switches46) that are provided respectively on the plurality of power lines and switch supply and shutoff of the electric power from the safety circuit18to the plurality of solenoids52, by being controlled by the control circuit16.

Thus, the control unit12only performs power supply to the solenoids52of the plurality of solenoid valve units14through the common line and power lines that are power-supply lines. That is, control signals are sent and received between the control circuit16, and the safety circuit18and solenoid valve drive circuit20in the control unit12, and therefore no control line for supplying control signals is provided in the plurality of solenoid valve units14. As a result, it is possible to avoid short circuiting between control lines and power-supply lines in the solenoid valve units14, which might occur in the technique disclosed in U.S. Pat. No. 8,156,965.

Furthermore, the first switch36and the second switch38provide an interlock control on the solenoid valve drive circuit20and the plurality of solenoid valve units14, and the open/close switches46perform supply and shutoff of electric power to the individual solenoids52. This enables the interlock control and the driving of the solenoid valves to be carried out efficiently.

Moreover, the entire solenoid valve system10,10A to10C can be downsized because the control circuit16, the safety circuit18, and the solenoid valve drive circuit20are contained within the control unit12.

Here, an effect of the solenoid valve systems10,10A to10C will be described in more detail. If the control line30,32,70is short-circuited with a power line on one side, among the positive-side power lines42,84,86,90or the negative-side power lines44,50,82, then the power supply to the solenoid valve drive circuit20and the plurality of solenoid valve units14can be shut off by turning off the first switch36or the second switch38provided on the power line on the other side. Accordingly, existing solenoid valves, solenoid valve units, or solenoid valve manifold bases can be connected to the control unit12and used without any change. Further, the designer can set the solenoid valve systems10,10A to10C without considering functional safety like aforementioned short circuiting etc.

The safety circuit18further includes the safety control circuit40configured to perform diagnostic testing of the control unit12. Diagnostic testing such as pulse test etc. can thus be conducted easily. Further, because the safety control circuit40is incorporated in the control unit12, there is no need to adjust the time set for the pulse test considering cable length etc. or to modify the design of the interior of the control unit12to adapt it to the safety control circuit40. This improves convenience of the solenoid valve systems10,10A to10C.

In this case, the first switch36is provided on a common line (the positive-side power line42or the negative-side power line82) and the second switch38is provided between the other terminal of the driving power supply34and a plurality of power lines (the negative-side power lines44,50or the positive-side power lines84,86). Then, the safety control circuit40includes a first controller (the first microcomputer40a) configured to turn on/off the first switch36by being controlled by the control circuit16, the first diagnosis circuit40bconfigured to diagnose a state of the common line when the first switch36is turned on/off, a second controller (the second microcomputer40c) configured to turn on/off the second switch38by being controlled by the control circuit16, and the second diagnosis circuit40dconfigured to diagnose a state of the plurality of power lines when the second switch38is turned on/off.

Thus, it is possible to perform diagnosis for a fault of the first switch36or the second switch38and a short circuit of the positive-side power line42,84,86and the negative-side power line44,50,82with other wiring (e.g. the control lines30,32). Further, if the diagnosis indicates that one of the first switch36and the second switch38has a fault, or that the common line or power line on which one of the switches is disposed is short-circuited, then the power supply to the solenoid valve drive circuit20and the plurality of solenoid valve units14can be shut off by turning off the other switch. It is then possible to avoid a situation where the interlock control becomes impossible.

Further, as shown in the first modification ofFIG. 3, the control unit12further includes the input circuit62configured to output an input from the external device60to the control circuit16, and the input circuit62includes the diagnosis portion68configured to diagnose the input from the external device60. As a result, the solenoid valve system10A can be designed while considering safety measures for the input from the external device60.

Further, as shown in the first modification ofFIG. 3, the external connection unit66connectable to the solenoid64of an external solenoid valve is further provided for the control unit12. In this case, the common line (positive-side power line42) is connected to the positive-side terminal of the solenoid64of the external solenoid valve through the external connection unit66. In the solenoid valve drive circuit20, the external connection power line74is further provided to connect the negative side terminal of the driving power supply34and the negative-side terminal of this solenoid64through the external connection unit66. A third switching portion (another open/close switch76) for switching supply and shutoff of the electric power to that solenoid64by being controlled by the control circuit16is provided on the external connection power line74. It is thus possible to easily control the solenoid64of the solenoid valve provided externally.

As shown in the second modification ofFIG. 4, another solenoid valve unit80may be further provided for the control unit12. In this case, the common line (negative-side power line82) is connected to the negative-side terminal of the solenoid92of the other solenoid valve unit80. Further, another power line (another positive-side power line90) is further provided to connect the positive-side terminal of the driving power supply34and the positive-side terminal of this solenoid92. A fourth switching portion (the shutoff switch94) for switching supply and shutoff of the electric power to that solenoid92by being controlled by the control circuit16is provided on the other positive-side power line90. It is then possible to supply electric power to the solenoid92of the other solenoid valve unit80independently of the plurality of solenoid valve units14so as to drive the solenoid valve provided with the solenoid92.

Further, as shown in the third modification ofFIG. 5, the control unit12is formed of the control module12aincluding the control circuit16, and the output module12bdisposed between the control module12aand the plurality of solenoid valve units14and including the safety circuit18and the solenoid valve drive circuit20. Then, only the control module12a, or only the output module12b, can be replaced according to the specifications of the solenoid valve system10C.

The present invention is not limited to the embodiments described above, but can of course adopt various configurations based on the disclosure in the specification.