JP4633404B2 - Shut-off valve device - Google Patents

Description

  The present invention relates to a shut-off valve device that is built in a gas meter, for example, for emergency shut-off of flammable gas such as city gas and vice versa.

  For example, a so-called gas meter for city gas or LPG (liquefied propane gas) has a built-in shut-off valve device to prevent the occurrence of various dangerous situations due to gas leakage or accidental disappearance of a pilot fire. It is used.

  Specifically, a so-called microcomputer-equipped gas meter (also called a microcomputer meter) includes at least a flow measurement device, a microcomputer, a shut-off valve device, and a seismic sensing device, and is measured by the flow measurement device. The flow rate of the gas being monitored is monitored by a microcomputer. If the microcomputer determines that an abnormality such as a gas leak has occurred, or if an earthquake has occurred based on information such as the gas flow rate or its duration, the shut-off valve device is driven. Thus, the gas supply from the gas meter to the downstream side is shut off by changing the valve body from the open state to the shut-off state. Alternatively, for example, when the user leaves the house for a long period of time, the use of gas is suspended for a long period of time. Is input, the valve body is switched from the open state to the shut-off state.

  And when the abnormal situation is resolved, or when resuming the use of gas from the suspended use state that has been continued for a long time, after confirming safety, the person in charge of the user or the gas management company, etc. By pressing and forcibly releasing the cutoff release (open) execution command, the microcomputer drives the cutoff valve device to change the valve body from the cutoff state to the open state.

  As a drive system for the shut-off valve device as described above, a so-called electromagnetic valve system using an electromagnetic solenoid as a power source has been adopted. In this type of shut-off valve device, the valve body continues in a completely closed state or a fully opened state for a long period of time.

  For this reason, for example, when solenoid parts or valve body parts are stuck while they are kept open for a long period of time, and a dangerous state such as gas leakage occurs and emergency shutdown is necessary. In some cases, the valve body cannot be closed. Therefore, every time a predetermined time (period) elapses, so-called automatic test shut-off is performed in which the electromagnetic solenoid is energized and the valve body is moved to the closed state in anticipation of gas not being used. Has been proposed (Patent Document 1).

  Further, in recent years, a stepping motor that can obtain a sufficiently strong shaft output torque and a relatively strong shaft output torque can be obtained by using a relatively simple drive control circuit that does not require a feedback control system. The system used as a source has been proposed.

  In this stepping motor type shut-off valve device, the rotary motion of the output shaft of the stepping motor is converted into a linear motion by a motion conversion mechanism such as a worm gear mechanism or a cam mechanism, and the valve body driven by the motion conversion mechanism Is linearly moved in the perspective direction with respect to the conduction port (valve seat) to open and shut off the gas supply. More specifically, the valve body is set to be in a shut-off state by pressing it against the valve seat, and to be opened by sufficiently pulling the valve body away from the valve seat.

  However, as described above, in the shut-off valve device, in general, the valve body is often fixed in an open state or a shut-off state for a long period of time. For this reason, there is a possibility that sticking may occur between the rubber member of the valve body and the valve seat or in the motion conversion mechanism. Therefore, even in the case of a stepping motor type shut-off valve device, when the valve body is to be moved from the shut-off state to the open state, or conversely, it is to be fixed when trying to move from the open state to the shut-off state. There is a risk that the output torque of the stepping motor will be lost against the large drag caused by it, and the valve body cannot be moved.

  In order to eliminate such an inconvenience, a technique has been proposed in which the stress applied to the valve body in a shut-off state or an open state is slightly relaxed (Patent Document 2). That is, when moving the valve body from the shut-off state to the open state, or when moving the valve body from the open state to the shut-off state, after moving the valve body over the maximum distance, the stepping motor is slightly reversed. This is a technique of relieving the stress between the valve body and the valve seat, for example, by rotating.

Japanese Patent Laid-Open No. 11-132821 JP 2003-194252 A

  However, the solenoid valve type shut-off valve device can only be in either a completely closed state (also referred to as a shut-off state) or a fully open state (also referred to as an open state). Therefore, automatic test shut-off must be performed in anticipation of the time when the user is not using any gas.

  However, for example, a user who frequently consumes gas all day long, there is almost no case when no gas is used at all, so automatic test shut-off cannot be performed, and sticking cannot be avoided. was there.

  On the other hand, when the user is away for a long period of time or when the vacant house state continues, the shutoff valve device is shut off for a long period of time to ensure safety. In such a case, if the shut-off state continues for a long time, the valve body and the valve seat may stick to each other in that state, or the electromagnetic solenoid may stick.

  However, a method for returning to the automatic test, in other words, for preventing sticking in such a cut-off state has not been proposed.

  Alternatively, in order to prevent sticking in such a shut-off state, it is considered that the valve body may be moved in the direction opposite to the automatic test shut-off. However, in actuality, for example, if there is a possibility of gas leakage due to deterioration of the piping on the downstream side of the gas meter over a long period of time, if the valve body is automatically returned to the test state and opened, gas leakage will actually occur. There is a risk of it.

  Even if the above-described method of slightly relaxing the stress applied to the valve body in the shut-off state or the open state is applied to a stepping motor type shut-off valve device, for example, the valve body and the valve seat are in contact in the shut-off state. Since they are in a state of being in contact with each other, they cannot escape their sticking.

  That is, since the gas meter is generally installed outdoors, the rubber member of the valve body is deteriorated due to the temperature and humidity under the environment, and this causes the valve body and the valve seat to be fixed. In order to prevent such sticking by the above technique, the position of the valve body (pressing stress) must be loosened until it does not come into contact with the valve seat. Not realistic.

  Further, when the valve body is kept open for a long period of time, there is no possibility of occurrence of sticking between the valve body and the valve seat. However, for example, the motion conversion mechanism is fixed internally while the output shaft of the stepping motor and the bearing are fixed while the valve is kept open for a long period of time. There is a possibility that it cannot be moved to.

  Such sticking in the open state cannot be prevented by the above method. This is because even if the stepping motor is rotated slightly backward and stopped after the valve element has been opened to the maximum, the state remains unchanged after the stop. It is because it cannot be avoided about fixing.

  Alternatively, it is conceivable to apply the automatic test shut-off method proposed in the electromagnetic valve system to this stepping motor type shut-off valve device. However, in reality, there is a risk that another risk increases. In other words, if the user is in a state of using gas, the fire is extinguished or the normal gas consumption state cannot be continued, for example, when the user is using the gas range. There is a risk that.

  Thus, with the conventionally proposed methods, it has been extremely difficult or impossible to prevent sticking in the shut-off valve device while ensuring safety during use or shut-off of the gas.

  Here, when the valve body is moved from the shut-off state to the open state (fully open state), there is a higher probability of sticking than when the valve body is moved from the open state to the shut-off state. Although it tends to be easy, the risk of gas supply is low. On the other hand, when the valve body is moved from the open state to the shut-off state, the probability of occurrence of sticking is low. However, since the shut-off cannot be performed in an emergency, the risk of gas supply is high. Therefore, in both of these cases, it is required to prevent the occurrence of the immovable state of the valve body due to the sticking.

  The present invention has been made in view of such problems, and its purpose is to prevent occurrence of sticking while avoiding occurrence of problems related to fluid flow such as gas leakage and gas supply failure, and is always normal. An object of the present invention is to provide a shut-off valve device capable of ensuring a state in which valve operation is performed.

A first shutoff valve device according to the present invention includes a valve body, a conduction port provided so as to shut off a fluid flow by being blocked by the valve body, a stepping motor, and an output shaft of the stepping motor. A motion conversion mechanism that converts rotational motion into linear motion to move the valve element relative to the conduction port; and a drive control circuit that inputs drive voltage to the stepping motor to control drive of the stepping motor. The shut-off valve device further includes pressure value measuring means for measuring a pressure value downstream of the valve body, and the drive control circuit has a pressure value measured by the pressure value measuring means is large. At least one of a case where the pressure threshold value is equal to or higher than a predetermined pressure value exceeding the atmospheric pressure, or a case where the temporal change in the measured pressure value is equal to or lower than a predetermined change threshold value. When the valve body continues to be closed for a predetermined period or more or every time the predetermined period has elapsed, the valve body is moved from the closed state to a predetermined half-open position, and then again The drive control is performed so as to return to the closed state .

  In the first shut-off valve device, the drive control circuit is fixed in the fully closed state when the valve body continues in the fully closed state for a predetermined period or more or every elapse of the predetermined period. In order to prevent this, the valve body is moved from the fully closed state to a predetermined half-open position. And after moving to the half-open state, it returns to a closed state (blocking state) again.

  The pressure control unit further includes a pressure value measuring unit that measures a pressure value downstream of the valve body, and the drive control circuit has a predetermined pressure value measured by the pressure value measuring unit that is greater than atmospheric pressure. When the pressure threshold value is equal to or greater than the set threshold value, or when the measured pressure value changes over time below a predetermined change threshold value, or at least one of them (or both) If the valve body continues to be closed for a predetermined period or more or every predetermined period, the valve body is moved from the closed state to a predetermined half-open position. Then, the drive control may be performed so as to return to the closed state after that.

  That is, when the pressure value downstream of the valve body is equal to or higher than the pressure threshold value set to a predetermined value exceeding atmospheric pressure, it is a factor that causes the leakage of fluid such as gas on the downstream side. It can be assumed that no situation has occurred. Further, when the temporal change in the measured pressure value is equal to or less than a predetermined change threshold value, it can be considered that the user has not started using a fluid such as a gas on the downstream side. . Therefore, in this case, even if the valve body is moved from the completely closed state to the predetermined half-open position, there is less possibility of causing a dangerous situation such as gas leakage.

  Furthermore, it is further desirable that the position of the valve body in the half-open state is set to a position where the flow rate of the fluid flowing downstream is less than a minute leakage flow rate detection threshold value.

  That is, by setting in this way, when the position of the valve body is changed from the fully closed state to the half-open state, a situation has arisen that may cause a dangerous situation such as a slight gas leak on the downstream side. However, since the flow rate of the fluid flowing between the valve body and the conduction port to the downstream side is less than the threshold value for detecting the minute leak flow rate, it is possible to avoid various dangerous situations caused by the minute gas leak. Is done.

  In addition, the drive control circuit does not perform a control operation to bring the valve body into the half-open state when the valve body is in a closed state under conditions set for avoiding a predetermined danger. Also good.

  That is, if the valve body is in a half-opened state when the valve body is in a closed state under conditions set for avoiding danger, the meaning of blocking for avoiding the danger of turning corners is lost. Therefore, in such a case, even if the various conditions as described above are satisfied, the control operation for making the valve element half open is not performed.

  Note that the fluid is a flammable gas, and the valve body, the conduction port, the stepping motor, the motion conversion mechanism, and the drive control circuit are used in the gas meter. This is a desirable embodiment. That is, the first or second shut-off valve device described above can be used particularly suitably in a so-called gas meter or the like for measuring the flow rate of city gas or LP gas, for example.

  According to the shut-off valve device of the present invention, it is possible to prevent the occurrence of a sticking state and always ensure a state in which normal valve operation is performed without causing inconvenience relating to the fluid flow state such as gas leakage or gas supply failure. It becomes possible to do.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic diagram showing a schematic configuration of a gas meter having a built-in shut-off valve device according to an embodiment of the present invention. FIG. 2 is a partial view of a stepping motor, a motion conversion mechanism, and a valve body used therein. FIG. FIG. 3 is a diagram schematically showing an operation by the first sticking prevention logic for returning the position (state) of the valve body 2 from the fully closed state to the half open state and then returning the valve body 2 to the fully closed state again. In FIG. 1, in order to clearly express the internal configuration of the conduction path container, the front portion of the conduction path container is partially cut off.

  The shutoff valve device in this gas meter includes a conduction port 1, a valve body 2, a stepping motor 3, a motion conversion mechanism 4, a drive control circuit 5, a return button device 6 as a valve body movement command input means, and a shutoff key. The main part is comprised from the apparatus 7 and the flow volume change detection circuit 8 as a valve body movement detection means. This shut-off valve device is built in a gas meter for combustible gas such as city gas or LP gas.

  The conduction port 1 is provided in a conduction path container 9 that conducts gas. The periphery of the conduction port 1 is a valve seat 10, and the peripheral edge of the valve body 2 made of a rubber member is pressed against and closely adhered to the valve seat 10, so that the gas flow is blocked.

  The valve body 2 is affixed to the surface (lower surface in FIG. 2) of the flange plate portion 11 of the motion conversion mechanism main body 12, and when the motion conversion mechanism main body 12 moves linearly, the conduction port 1 together with the motion conversion mechanism 4. Is set to move linearly in the perspective direction. The valve body 2 is made of a highly flexible and elastic member such as a synthetic rubber so as to be surely cut off the gas conduction by being pressed against the valve seat 10.

  The motion conversion mechanism 4 includes a motion conversion mechanism main body 12, worm teeth 13, a guide notch 15, and a guide plate 16. The motion conversion mechanism main body 12 is set so that the stepping motor 3 is accommodated inside the cylindrical side wall 14 with a predetermined dimensional play and can move along the cylindrical side wall 14. ing. Further, a guide notch 15 is provided in the side wall 14, and a guide plate 16 provided so as to protrude from the side surface of the stepping motor 3 is inserted with a predetermined dimensional play. A receiving hole 18 formed by engraving a female thread-like worm tooth receiving groove 17 is provided in the approximate center of the bottom. On the other hand, the worm tooth 13 is provided near the tip of the output shaft 19 of the stepping motor 3 and meshes with the receiving hole 18 of the motion conversion mechanism main body 12.

  In the motion conversion mechanism 4, the worm teeth 13 move in the axial direction relative to the receiving hole 18 in accordance with the rotation of the output shaft 19 of the stepping motor 3. The conversion mechanism main body 12 moves relative to the stepping motor 3, and the valve body 2 attached to the surface of the flange plate portion 11 of the motion conversion mechanism main body 12 is connected to the conduction port 1 (valve seat 10). On the other hand, it moves in the perspective direction. In this manner, in the motion conversion mechanism 4, the rotational motion of the output shaft 19 of the stepping motor 3 is converted into the linear motion of the valve body 2.

  The stepping motor 3 is a general motor whose output torque changes according to the frequency of the drive voltage waveform, for example. That is, when the frequency is increased, the torque is reduced, and when the frequency is decreased, the torque is increased. Alternatively, the output torque varies depending on the duty ratio, effective voltage value, or average voltage value (waveform average value) of the drive voltage waveform. Of course, various combinations of drive control are possible by combining them. Needless to say, any number of poles and motor size may be used as long as the power consumption is as low as possible and a desired torque can be output.

  The return button device 6 and the cutoff key device 7 are means for inputting a command for moving the valve body 2 (also referred to as a valve body movement command). When the button 61 is pressed by the user, a gas manager, or the like, the return button device 6 inputs a command signal for moving the valve body 2 from the shut-off state to the open state to the drive control circuit 5. Further, for example, when the electromagnetic key 71 stored outside the gas meter is brought close to the cutoff key device 7, the cutoff key device 7 turns on the reed switch 72 built in the cutoff key device 7, A command signal for moving the body 2 from the open state to the shut-off state is input to the drive control circuit 5. Of course, the return button device 6 and the cutoff key device 7 themselves may be general ones.

  The flow rate / pressure measuring circuit 8 is measured by a gas flow rate value Q measured by a flow rate measuring device (not shown) provided downstream of the conduction path container 9 and a pressure measuring device (not shown). A gas pressure value P is calculated.

  The drive control circuit 5 inputs a drive voltage and drives the stepping motor 3. The output torque of the stepping motor 3 is controlled by setting the frequency (or duty ratio, average voltage value, or combination thereof) of the driving voltage input to the stepping motor 3. Then, the rotational speed N (or rotational angle θ) of the stepping motor 3 is controlled by the total number of drive voltage pulses input to the stepping motor 3, and the linear motion of the valve body 2 is controlled with sufficient practical accuracy. Is set to be able to.

  The drive control circuit 5 also has a function of executing control for moving the valve body 2 in response to a valve body movement command input by the return button device 6 or the shutoff key device 7, or a so-called seismic effect. It has a general blocking function such as blocking.

  The drive control circuit 5 may be constructed in software using a so-called microcomputer (microcomputer or MPU; microprocessing unit) as hardware, or by mounting discrete electronic components on a printed wiring board. Of course, it may be constructed.

  The drive control circuit 5 has a function of performing drive control on the stepping motor by the following sticking prevention logic. That is,

[1] First sticking prevention logic;
As shown in FIG. 3, when the valve body 2 continues in the fully closed state for a predetermined period Tth or more, or at every timing of the predetermined period Tth, the valve body 2 is moved from the fully closed state (A) to a predetermined position. To a half-open state (B). And then, it returns to the fully closed state (C) again. However, the drive control by such sticking prevention logic is performed when the conditions as summarized in the following conditions (a) and (b) are further met.

  Condition (a): The pressure value P of the measured gas is equal to or greater than the pressure threshold value Pth (P ≧ Pth). The pressure threshold value Pth is set to a predetermined value (Pth> Pair) exceeding the atmospheric pressure Pair.

  That is, when the valve body 2 is in the fully closed state but the user accidentally tries to use the gas and opens the gas stopper at the downstream end, the valve body 2 in the fully closed state is However, the pressure value P on the downstream side rapidly decreases to less than the pressure threshold value Pth or equal to the atmospheric pressure Pair. In other words, when the pressure value P is lower than the pressure threshold value Pth to the atmospheric pressure Pair, the probability that the gas stopper at the downstream end is open is extremely high. And when the gas stopper of the downstream end is in the open state in this way, if the user makes the valve body 2 half open, there is a risk of inadvertently injecting gas on the user side (downstream end). There is. Therefore, in order to avoid such inconvenience, the determination using the pressure threshold as in the above condition (a) is performed. That is, when the measured gas pressure value P is equal to or greater than the pressure threshold value Pth (P ≧ Pth), the downstream end gas stopper is closed (or no gas is used). Therefore, even if the valve body 2 is in a half-open state, it can be determined that an inadvertent gas ejection does not occur. Therefore, the valve body 2 is controlled to be in a half-open state ((A) → (B) in FIG. 3). (C)). However, when the measured gas pressure value P is less than the pressure threshold value Pth (P <Pth), the gas stopper at the downstream end is in an open state, so that an inadvertent ejection of gas occurs. Since it is determined that there is a risk, the valve body 2 is not controlled to be in a half-open state, and is kept in a fully closed state (maintains the state shown in FIG. 3A).

  Condition (b): When the temporal change rate ΔP / Δt of the measured gas pressure value P is equal to or less than a predetermined change threshold value (ΔP / Δt) th (ΔP / Δt ≦ (ΔP / Δt) th) .

  That is, when a gas leak or some other abnormal situation occurs on the downstream side of the valve body 2, a sharp change exceeding the change threshold value (ΔP / Δt) th occurs in the pressure value P. There are many. In other words, if the pressure value P undergoes a steep change exceeding the change threshold value (ΔP / Δt) th, there is a probability that a gas leak or some other abnormal situation has occurred. That is expensive. Contrary to this, when the temporal change rate ΔP / Δt of the gas pressure value P is equal to or less than a predetermined change threshold value (ΔP / Δt) th (ΔP / Δt ≦ (ΔP / Δt) th). Means that there is a low probability that a gas leak or some other abnormal situation has occurred. Further, if the temporal change rate ΔP / Δt of the gas pressure value P is so low that it cannot be determined that the gas leak has occurred, the probability of inconvenience occurring even if the valve body 2 is in the half-open state is extremely low. It is assumed that For this reason, when ΔP / Δt ≦ (ΔP / Δt) th, the valve body 2 is controlled to be in a half-open state ((A) → (B) → (C) in FIG. 3). When ΔP / Δt> (ΔP / Δt) th, the control to make the half-open state is not performed and the fully closed state is kept (the state of FIG. 3A is kept).

  Further, the position of the valve body 2 in the above-mentioned half-open state (FIG. 3B) is such that the flow rate value Q of the gas flowing downstream according to the opening degree of the valve body 2 is a predetermined minute leakage flow rate detection threshold. It is preferable to set the position S1 so that it is less than the value Qlow-th (Q <Qlow-th). By setting in this way, the flow rate of gas flowing downstream can be suppressed to less than the minute leak flow detection threshold Qlow-th, and the duration time of the half-open state is short, so even if the gas leaks on the downstream side Even if some event that causes the problem is actually occurring, the flow rate of the gas flowing downstream (the integrated flow rate during the duration of the half-open state) is kept to a very small level, This is because inconvenience and danger can be avoided.

  Here, either one of the above conditions (a) and (b) may be a precondition for controlling the half-open state, but the condition (a) and the condition (b) may be preconditions. Good. This is because, by setting the condition (a) and the condition (b), it is possible to further avoid the various disadvantages as described above.

[2] Second sticking prevention logic;
As shown in FIG. 8, when the valve body 2 continues the fully open state for a time equal to or longer than the predetermined period Tth, or at every timing when the predetermined period Tth elapses, the valve body 2 is fully opened (FIG. 8 (A )) To a predetermined position S2 in the half-closed state (FIG. 8B). After that, it is returned to the fully opened state (FIG. 8C).

  However, the case where the drive control by such sticking prevention logic is performed is a case where the measured gas flow rate value Q is less than or equal to a predetermined flow rate threshold value Qhigh-th to more than 0 (Qhigh-th ≧ Q > 0). Here, the flow rate threshold value Qhigh-th is the maximum of the flow rate range that is assumed not to cause a supply failure even if the valve body 2 is in a semi-closed state when the gas is being consumed on the downstream side. It is set as a flow rate value.

  Further, as the position S2 of the valve body 2 in the semi-closed state (FIG. 8B), the flow rate value Q of the gas flowing according to the opening degree of the valve body 2 is consuming gas on the downstream side. Even if it exists, it is suitable to set so that it may become the value below the flow rate threshold value Qhigh-th set as what does not produce supply failure. This is because, if these conditions are satisfied, for example, even if the valve body 2 is in a semi-closed state when the user is using gas on the downstream side, a gas supply failure to the user's gas consuming device or the like occurs. This is because there is a very low risk of this.

  In addition to the above, for example, when the measured gas flow rate value Q is 0 and stable, it can be considered that the user does not consume gas downstream. Therefore, in this case, the valve body 2 is moved from the fully open state to the fully closed state when the valve body 2 continues the fully open state for a predetermined period Tth or more, or every predetermined period Tth, and then You may make it return to a full open state. Or, conversely, in the fully closed state, it may be moved from there to the fully open state and then returned to the fully closed state again.

  Further, when the valve body 2 is in a fully closed state as a so-called emergency shut-off under a predetermined condition set for avoiding a danger, for example, when an earthquake occurs, the above [1], [2] Needless to say, it is desirable to continue the fully-closed state without performing the control operation for bringing the valve body 2 into the half-opened state even at the timing when the drive control by the sticking prevention logic is to be performed.

  Next, the operation of this shut-off valve device will be described.

  4, 5 and 9 are simplified flowcharts showing the main flow of the operation of the shut-off valve device.

  In this first sticking prevention logic, as shown in FIG. 4, the time information is reset to T = 0 (S1), and time counting is started (S2). Monitoring of the value of T is continued (N loop of S2), and when a predetermined time Tth elapses and the time count reaches T = Tth (Y of S2), a series of operations by the sticking prevention logic is executed. (S3). Here, the sticking prevention logic of S3 is a generic term for both the first and second.

  Alternatively, although not shown, for example, T = 24 hours is set, and drive control by the sticking prevention logic is performed once a day, for example, at a fixed time of midnight such as 3:00 am. It may be. Alternatively, T may be set to a longer period, for example, once every 30 days. As the time T is set to a longer time, the number of executions per unit time of the drive control operation by the sticking prevention logic decreases, and the probability that sticking occurs during the long one cycle increases. In trade-off, the amount of power consumed by the operation by the sticking prevention logic can be reduced. Conversely, the shorter the setting is, the more the number of executions of the drive control operation by the sticking prevention logic increases, and the probability of sticking occurring during that period decreases. However, this is a tradeoff and is repeated frequently. The amount of power consumed in the operation by the sticking prevention logic is increased. Therefore, it is desirable to set the time T to an appropriate value in consideration of such advantages and disadvantages.

  In the first sticking prevention logic for performing the half-open state, as shown in FIG. 5, first, it is detected whether the valve body 2 is in a closed state or an open state at that time (S51). When it is in the closed state as shown in FIG. 3A (Y in S51), the pressure value P at that time is further measured (S52). Then, the pressure value P is compared with the pressure threshold value Pth (S53).

  As a result of the comparison, if P ≧ Pth (Y in S53), then gas leakage or abnormal pressure drop occurs in piping and various gas appliances (all not shown) downstream from the shutoff valve device. It can be determined that it is not. This is because the magnitude relationship is set as Pth> Pair, so if a leak occurs, the pressure value P decreases and P <Pth, or further decreases, and P = Pair is likely to occur. If the opposite is true (that is, if P ≧ Pth), there is a low probability that a gas leak or the like has occurred. Therefore, in the case of Y in S53, as shown in FIG. 3B, the valve body 2 is moved to a predetermined position S1 to be in a half-open state (S54). By performing this movement, it is possible to prevent the valve body 2 from being stuck in the fully closed state.

  Here, in the drive control operation by the first sticking prevention logic, the valve body 2 is moved to the position S1 where the flow rate value Q of the gas flowing downstream is less than the minute leak flow rate detection threshold value Qlow-th. Is set to

  In the shut-off valve device having the structure as shown in FIG. 1, when the valve body 2 is throttled from the fully open state to the fully closed state, the flow rate Q decreases steeply from the vicinity of a predetermined position S2 in the stroke. Start. Specifically, when the position of the valve body 2 (position when the fully open position is set to the reference point S = 0) S is taken on the horizontal axis and the corresponding flow rate Q is taken on the vertical axis as an index of opening. It has been confirmed by experiments by the present inventor that the SQ graph draws a very characteristic curve as shown in FIG. That is, the flow rate Q that can flow corresponding to the opening degree is gradually reduced from Q0 in the fully opened state in correspondence with narrowing down the opening degree (position S) of the valve body 2. Absent. This tendency continues to a position S2 that is unexpectedly far from the fully open state. From the vicinity of the position S2, the flow rate Q decreases sharply and reaches less than Qlow-th. A position (opening degree) corresponding to the flow rate Qlow-th is defined as S1. By setting the position S1 as the position of the valve body 2 in the half-open state, even if there is a factor of minute leakage on the downstream side in the half-open state, the minute leak flow detection threshold Qlow-th It can be stopped only by flowing a gas having a flow rate less than that.

  And after making the valve body 2 into a half open state (FIG. 3 (B)), as shown to FIG. 3 (C), it returns to a fully closed state (S55). The movement of the valve body 2 at this time can also prevent sticking of the valve body 2 and the mechanical operation of the motion conversion mechanism 4 or the like. Here, since there is no need to continue the half-open state itself, it is desirable to immediately return to the full-closed state after the half-open state.

  Here, as a condition for determining whether or not to execute the operation by the first sticking prevention logic, in addition to comparing the pressure value P as shown in S53 in FIG. 5 with Pth, It is also possible to apply a variation as shown as S73 in FIG. That is, the temporal change rate (ΔP / Δt) of the pressure value P is measured, and the temporal change rate is set as a predetermined value that is equal to or greater than the maximum value of the pressure change rate due to, for example, a natural change in the environmental temperature. If it is equal to or less than the change threshold value (ΔP / Δt) th (Y in S73), the probability of gas leakage occurring at that time and the probability that the user has started using the gas appliance at the downstream side are low. Therefore, even if the valve body 2 is in a half-open state for a short time, the risk is extremely low. Therefore, in this case, an operation for moving the valve body 2 to a half-open state is performed.

  Alternatively, S53 and S73 are combined, and when P ≧ Pth (Y in S53) and ΔP / Δt ≦ (ΔP / Δt) th (Y in S73), the valve body 2 is moved to the half-open state. It is also possible to perform the operation in the case of P <Pth (N in S53) or in the case of ΔP / Δt> (ΔP / Δt) th (N in S73).

  In this way, according to the first sticking prevention logic, the valve body 2 can be prevented from sticking in the fully closed state.

  FIG. 8 is a diagram schematically showing the operation by the second sticking prevention logic for returning the position (state) of the valve body 2 from the fully open state to the semi-closed state and then returning to the fully open state. It is a simple flowchart showing the main flow of the operation.

  The start timing and the period T of the second sticking prevention logic are as already described with reference to FIG.

  In the second sticking prevention logic, as shown in S51 of FIG. 5 and FIG. 9, first, it is detected whether the valve body 2 is closed or open at that time (S51 of FIG. 5). When it is in the open state as shown in FIG. 8A (N in S51), the flow rate value Q at that time is further measured (S91 in FIG. 9). Then, the flow rate value Q is compared with a flow rate threshold value Qhigh-th (S92).

  As a result of the comparison, if 0 <Q ≦ Qhigh-th (Y in S92), even when the valve body 2 is throttled to the semi-closed state at that time, even if the gas is being used on the downstream side There is no risk of gas supply failure. Therefore, as shown in FIG. 8B, the valve body 2 is moved to a predetermined position S2 to be in a semi-closed state (S93). By performing this movement, it is possible to prevent the valve body 2 from being stuck in the fully opened state.

  In the drive control operation in the semi-closed state, the valve body 2 is set to move to a predetermined position S2 corresponding to the flow rate threshold value Qhigh-th. With such a setting, when gas is consumed on the downstream side at this time, even if the valve body 2 is in a semi-closed state, it is sufficient to prevent supply failure on the downstream side. A flow rate of gas can flow.

  And after making the valve body 2 into a semi-closed state, as shown in FIG.8 (C), it returns to a full open state (S94). Also by the movement at this time, it is possible to prevent sticking of the valve body 2 and astringent mechanical operation of the motion conversion mechanism 4 or the like. Here, since there is no need to continue the semi-closed state, it is desirable to immediately return to the fully open state after the semi-closed state.

  In this way, it is possible to prevent the valve body 2 from sticking in the fully opened state.

  In addition to the above, when the measured gas flow rate value Q is 0, it can be considered that the user does not consume gas downstream. Therefore, in such a case, when the valve body 2 continues to be opened for a predetermined period Tth or more, or every time the predetermined period Tth elapses, the valve body 2 is changed between the fully open state and the fully closed state. It may be moved over the entire stroke.

  Further, when the valve body 2 is automatically in a fully closed state under a predetermined condition set for avoiding danger, for example, so-called seismic shut-off when an earthquake occurs, the valve body 2 is Needless to say, it is desirable to continue the closed state without performing the control operation for the half-open state.

  Needless to say, the position S1 of the valve body in the half-open state and the position S2 of the valve body in the half-closed state are not limited to the above settings. As the position S1 in the half-open state, basically (qualitatively speaking), the valve body 2 and the valve seat 10 are completely separated from each other, and the motion conversion mechanism 4 is necessary to escape from the movement agitation and the fixed state. It is desirable to set the position where a sufficient stroke can be secured.

  The shut-off valve device according to the present invention can be used by being incorporated in a gas meter in order to prevent leakage of combustible gas such as city gas or LP gas. Alternatively, the present invention can also be applied as a shut-off valve device for liquid such as liquid fuel or liquefied fuel.

It is a schematic diagram showing the schematic structure of the gas meter which incorporates the cutoff valve apparatus which concerns on one embodiment of this invention. FIG. 3 is a partially omitted cross-sectional view showing a stepping motor, a motion conversion mechanism, and a valve body partially extracted. It is the figure which represented typically the operation | movement by the 1st sticking prevention logic which returns a valve body from a fully-closed state (A) to a half-open state (B), and returns to a fully-closed state (C) again. It is a flowchart showing the execution start timing of the sticking prevention logic. It is a flowchart showing the main flow of the operation | movement by the 1st sticking prevention logic. It is a graph showing a typical example of the SQ curve which shows the correlation with the position S of a valve body, and the flow volume Q corresponding to it. It is a figure showing 1 variation of the conditions (determination step) for determining whether the operation | movement by the 1st adhesion prevention logic is performed. It is the figure which represented typically the operation | movement by the 2nd sticking prevention logic which returns a valve body from a full open state (A) to a semi-closed state (B), and returning to a full open state (C) again. It is a flowchart showing the main flow of the operation | movement by the 2nd sticking prevention logic.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Conduction port, 2 ... Valve body 2, 3 ... Stepping motor, 4 ... Motion conversion mechanism, 5 ... Drive control circuit, 6 ... Reset button device, 7 ... Shut-off key device, 8 ... Flow rate / pressure measurement circuit, 9 ... Conduction path container, 10 ... valve seat, 11 ... flange plate portion, 12 ... motion conversion mechanism main body, 13 ... worm tooth, 15 ... guide notch, 16 ... guide plate, 17 ... worm tooth receiving groove, 18 ... receiving hole, 19 ... Output shaft

Claims (4)

The valve body, a conduction port provided to block the flow of fluid by being blocked by the valve body, a stepping motor, and the rotary motion of the output shaft of the stepping motor are converted into linear motion to convert the valve A shut-off valve device comprising a motion conversion mechanism that performs a moving motion with respect to the conduction port of a body, and a drive control circuit that inputs a drive voltage to the stepping motor and performs drive control of the stepping motor;
A pressure value measuring means for measuring a pressure value downstream of the valve body;
In the drive control circuit, when the pressure value measured by the pressure value measuring unit is equal to or more than a pressure threshold value set to a predetermined value exceeding atmospheric pressure, or the time change of the measured pressure value is In the case where it falls under at least one of the cases where the change threshold value is less than or equal to the predetermined change threshold value, the valve body is kept closed for a predetermined period or more or every time the predetermined period elapses. A shut-off valve device , wherein the drive control is performed so that the body is moved from the closed state to a predetermined half-open position and then returned to the closed state . Claim 1, wherein the position of the valve body in the half-open, in a position such that the flow rate of the fluid flowing to the downstream side is smaller than a predetermined minute leakage flow detection threshold, characterized by comprising setting cut-off valve device according to. The drive control circuit does not perform a control operation for bringing the valve body into the half-open state when the valve body is in a closed state under a condition set for avoiding a predetermined danger. The shut-off valve device according to claim 1 or 2 . The fluid is a combustible gas;
The valve and body, and the conductive opening, wherein a stepping motor, the a motion converting mechanism, and the said drive control circuit, of the claims 1 to 3, characterized in that used built in the gas meter The shut-off valve device according to any one of the above.

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