Valve System

Abstract

To provide a valve system capable of more rapidly estimating a valve opening position of a blocking valve.SOLUTION: A valve system 1 comprises a tank 2 which can store fluid, a pressure sensor 6 which detects an inner pressure of the tank 2, a valve 4 which includes a valve body 11 and opens and closes the tank 2, a driving device for stroking the valve body 11 of the valve 4, and a control device 5. The control device 5 continuously opens a closed valve 4 at a constant valve opening speed by operating the driving device. When the pressure sensor 6 detects that the inner pressure in the tank 2 decreased by a constant value, the control device stores a position of the valve body 11 or stops the valve body 11. The control device estimates a valve opening position of the valve 4 on the basis of a storage position of the valve body 11 or a stop position and a valve opening quantity of the valve body 11 till the inner pressure predetermined for the inner pressure before opening of the tank 2 decreases by a constant value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a valve system, and more particularly to a valve system including a tank capable of storing a fluid and a valve capable of opening and closing the tank. [Background technology]

[0002] Vehicles, such as automobiles, equipped with engines are equipped with an evaporated fuel treatment system that includes a fuel tank and a canister that adsorbs fuel vapor generated within the fuel tank. Typically, the vapor passage connecting the fuel tank and the canister is blocked by a shutoff valve, which opens only when the vapor needs to be adsorbed into the canister. In the system disclosed in JP 2018-100643 A, the opening degree of the shutoff valve is adjusted using a stepping motor. Because the opening position of the valve element of the shutoff valve varies depending on the environment and the component tolerances of the shutoff valve, it is necessary to grasp the valve opening position. In the above system, the shutoff valve is opened in two steps from a closed state, and the valve opening position is estimated based on the change in fuel tank pressure that accompanies the valve opening operation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-100643 Summary of the Invention [Problem to be solved by the invention]

[0004] In the valve system of the above publication, whether the valve has opened is estimated based on the change in tank pressure every two steps of the valve opening operation. As a result, it takes time to estimate the valve opening position. Therefore, it is desirable to provide a valve system that can estimate the valve opening position more quickly. [Means for solving the problem]

[0005] One aspect of the valve system includes a tank capable of storing a fluid, a pressure sensor having a valve element and detecting the internal pressure of the tank, a valve for opening and closing the tank, a drive device for stroking the valve element of the valve, and a control device. The control device is configured to operate the drive device to continuously move the valve element in a closed state in the opening direction at a constant valve opening speed, to store the position of the valve element or to stop the valve element when the pressure sensor detects that the internal pressure of the tank has decreased by a predetermined value, and to estimate the valve opening position based on the stored or stopped position of the valve element and the amount of opening of the valve element until the internal pressure of the tank decreases by a predetermined value compared to the internal pressure before the valve opening. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a configuration diagram of a valve system according to a first embodiment. [Figure 2] 4 is a time chart illustrating a method for estimating a valve opening position. [Figure 3] 10 is a graph showing the valve opening speed and the valve opening amount based on the internal pressure before the tank is opened. [Figure 4] 1 is a graph showing estimated open and parked positions of a valve. [Figure 5] 4 is a graph showing the open position and standby position of the valve as determined by the control device. DETAILED DESCRIPTION OF THE INVENTION

[0007] <Valve system> Various embodiments will be described below with reference to Figures 1 to 5. As shown in Figure 1, the valve system 1 has a tank 2 that forms a closed space for storing a fluid, a supply destination 7 for the fluid in the tank 2, and a supply channel 3 that connects the tank 2 to the supply destination 7. The valve system 1 has a valve 4 that can open and close the supply channel 3. When the valve 4 is opened, the fluid in the tank 2 flows through the supply channel 3 into the supply destination 7. The supply destination 7 can be, for example, a fuel cell, in which case the valve system 1 is applied to a hydrogen fuel supply system equipped with a hydrogen tank that supplies hydrogen fuel to the fuel cell, for example.

[0008] The valve system 1 includes a pressure sensor 6 that measures the internal pressure P of the tank 2, and a control device 5. The control device 5 is a computer system that includes at least one processor and at least one memory. A measurement signal from the pressure sensor 6 is input to the control device 5. The control device 5 also outputs a control signal to control the operating state of the valve 4. The memory of the control device 5 stores various programs and various data (including maps) for controlling the valve 4. The programs stored in the memory are executed by the processor to realize the controls described below. For example, control of the flow rate of a fluid through the valve 4 is one of the functions realized by executing the programs.

[0009] <Valve> As shown in Figure 1, the valve 4 has a valve element 11 and a drive device (actuator) that strokes the valve element 11. The drive device has, for example, a stepping motor 12 equipped with a rotor and a stator, and an output shaft 13 extending upward from the valve element 11. The stepping motor 12 strokes the valve element 11 via the output shaft 13. More specifically, a male thread is formed on the surface of the output shaft 13. The output shaft 13 is assembled in a state where it is threadedly engaged with the rotor of the stepping motor 12. Therefore, the output shaft 13 moves in the axial direction (up and down) as the rotor rotates. As the output shaft 13 moves up and down, the valve element 11 also moves up and down.

[0010] In addition, a rubber seal member 14 is provided on the underside of the valve disc 11. When the valve disc 11 is lowered by the stepping motor 12, the seal member 14 is pressed from above against the seat portion 3a of the supply path 3. This allows the valve disc 11 to properly block the supply path 3 and seal the tank 2. Then, when the valve disc 11 rises and the seal member 14 is separated from the seat portion 3a, the upstream path 3b and the downstream path 3c become connected. This allows the fluid to flow from the tank 2 toward the supply destination 7.

[0011] The control device 5 can drive the stepping motor 12 to rotate in the forward or reverse direction by controlling the number of steps. By rotating the stepping motor 12 in the forward or reverse direction by a predetermined number of steps, the valve element 11 moves a predetermined stroke amount in the up and down direction (opening / closing direction). In other words, the stroke amount of the valve element 11 can be adjusted by controlling the number of steps.

[0012] The flow rate from the tank 2 to the supply destination 7 can be controlled by adjusting the stroke of the valve element 11 based on the valve open position where the sealing member 14 begins to separate from the seat 3a of the supply path 3. However, the open position of the valve 4 varies depending on the environment of the valve system 1 and the tolerances of the parts. Therefore, it is necessary to estimate the open position of the valve 4 before controlling the flow rate.

[0013] <Method for estimating valve opening position> Next, a method for estimating the open position of the valve 4 will be described with reference to Figure 2. The upper graph in Figure 2 shows the change in the internal pressure P of the tank 2 over time (horizontal axis). The internal pressure P of the tank 2 is measured by the pressure sensor 6, for example, at regular intervals. The lower graph in Figure 2 shows the change in the number of steps of the stepping motor 12 over time (horizontal axis), i.e., the stroke amount of the valve disc 11.

[0014] As shown in Figure 2, initially, the valve element 11 is lowered to a position where the step number of the stepping motor 12 is 0. This places the valve 4 in a closed state. First, the control device 5 continuously moves the valve element 11 in the valve opening direction at a constant speed (for example, 30 ms / step). Then, when the supply path 3 begins to open due to the valve opening operation of the valve element 11, the fluid in the tank 2 flows out and the internal pressure P of the tank 2 begins to decrease.

[0015] Next, the control device 5 monitors the internal pressure P of the tank 2, and when it detects that the internal pressure P of the tank 2 has decreased by a certain judgment pressure ΔP (for example, 0.2 kPa), it stops the valve opening operation of the valve element 11. The judgment pressure ΔP can be set as a multiple (for example, double) of the resolution (for example, 0.1 kPa) of the pressure sensor 6 used, but is not limited to this.

[0016] As long as the resolution of the pressure sensor 6 is finite, the stop position S1 of the valve disc 11 will be a position that is a certain amount of opening from the valve open position where the supply path 3 just begins to open. This valve opening amount is thought to depend not only on the reference pressure ΔP but also on the valve opening speed of the valve 4 and the internal pressure P of the tank 2 before it is opened. Therefore, measurements (or calculations based on these parameters) are made in advance for various valve opening speeds and internal pressures P, and the results are stored in the control device 5 in the form of a map or the like. Figure 3 shows the valve opening amount of the valve disc 11 according to the internal pressure P of the tank 2 before it is opened, i.e., the stop position S1 when the valve open position is used as a reference. ◯ indicates the case where the valve disc 11 is opened at 30 ms / step (stop position S1a). X indicates the case where the valve disc 11 is opened at 60 ms / step (stop position S1b). For example, if the valve opening speed is 30 ms / step and the internal pressure P before tank 2 is opened is 11 kPa, this indicates that valve 4 will open an amount equivalent to approximately 15 steps before tank 2 decreases by 0.2 kPa.

[0017] The control device 5 estimates the open position of the valve 4 based on the valve opening amount up to the stop determined in advance by measurement or calculation. Specifically, the control device 5 estimates the open position of the valve 4 to be a position S2 obtained by subtracting the above-mentioned predetermined valve opening amount from the stop position S1 of the valve 4 (estimated open position S2).

[0018] In another embodiment (not shown), the control device 5 may store the position (number of steps) of the valve element 11 at the time when it detects that the internal pressure P of the tank 2 has decreased by a certain threshold pressure ΔP. Then, instead of the stop position S1, it may estimate a position obtained by subtracting the predetermined valve opening amount from this stored position as the open valve position. This makes it possible to estimate the open valve position even when it is difficult to stop the valve element 11 immediately upon detecting the threshold pressure ΔP.

[0019] <Method of estimation when tank internal pressure is low> If the valve 4 opening speed is constant, the smaller the internal pressure P before the tank 2 is opened, the longer it takes for the internal pressure P to change, and therefore the amount of valve opening of the valve element 11 until the pressure change reaches the judgment pressure ΔP increases. For example, if the valve 4 opening speed is always set to 30 ms / step, and the internal pressure P before the tank 2 is opened is smaller than 11 kPa, it can be inferred from the trend of the graph in Figure 3 that the valve opening amount until the judgment pressure ΔP is reached will be larger. Opening the valve element 11 more than the open position in this way is not desirable, for example, when it is desired to suppress the flow rate from the tank 2 to the supply destination 7. Furthermore, there is a concern that an opening speed that is too fast may cause the valve element 11 to open more than usual.

[0020] Therefore, it is desirable to reduce the valve opening speed of the valve 4 when the internal pressure P of the tank 2 before opening is low. For example, by setting the valve opening speed of the valve 4 to 60 ms / step, the valve opening amount of the valve element 11 until the internal pressure P of the tank 2 drops by 0.2 kPa can be limited to 15 steps or less, as shown by the x marks in Figure 3. Even in such cases, the valve opening position of the valve 4 can be estimated by subtracting the previously measured valve opening amount until the valve 4 stops from the stop position S1 of the valve 4. In this way, by switching the valve opening speed of the valve 4 depending on the internal pressure P of the tank 2 before opening, the valve opening position can be accurately estimated without excessively increasing the flow rate. The specific valve opening speeds described above are merely examples, and any appropriate valve opening speed can be set depending on the internal pressure of the tank and the reference pressure. Furthermore, three or more speeds can be set depending on the internal pressure of the tank before opening.

[0021] <Valve standby position> After estimating the estimated valve opening position S2, as shown in FIG. 2, after waiting for a certain period of time required for the reversal of the valve 4, the valve 4 can be closed to the standby position S3. The standby position S3 is located closer to the closed valve side than the estimated valve opening position S2. For example, the standby position S3 can be set to a position where the valve is closed by 16 steps from the estimated valve opening position S2. By closing the valve 4 to the standby position S3, the valve 4 can be kept in an appropriately sealed state even when it is subjected to vibrations or the like from the surroundings. FIG. 4 shows the stop position S1, the estimated valve opening position S2, and the standby position S3 of the valve 4 corresponding to the internal pressure P in the tank 2 before opening. Note that the standby position S3 does not necessarily have to be a position closed by exactly 16 steps from the estimated valve opening position S2, and it may be located on the closed valve side from the estimated valve opening position S2.

[0022] <Rough estimation of valve opening position> As another embodiment, the control device 5 may roughly estimate the valve opening position of the valve 4 without using the data of the valve opening amount determined by pre-measurement or the like shown in FIG. 3. For example, when the data of the valve opening amount is obtained, when the internal pressure P in the tank 2 before opening is 11 kPa ≤ P ≤ 35 kPa, the valve opening speed is 30 ms / step, and when the internal pressure P in the tank 2 before opening is 2 kPa < P < 11 kPa, the valve opening speed is 60 ms / step. Thus, it is known in advance that the valve opening amount at the stop position S1 is 15 steps or less at any internal pressure within the above range. In such a case, as shown in FIG. 5, regardless of the internal pressure in the tank 2, a position S2 obtained by subtracting 15 steps from the stop position S1 of the valve 4 is regarded as the valve opening position (rough estimated valve opening position S2). At this rough estimated valve opening position S2, the valve 4 closes at least the supply passage 3. Therefore, the estimated valve opening position S2 can be determined more quickly. Then, the valve 4 may be made to standby at a position obtained by further subtracting a predetermined amount (for example, 16 steps) from the estimated valve opening position S2 (standby position S3).

[0023] As another embodiment, the position of the valve element 11 at the time when it is detected that the internal pressure P in the tank 2 has decreased by the determination pressure ΔP may be memorized, and a position obtained by subtracting a certain stroke amount (for example, 15 steps) from the memorized position may be regarded as the estimated valve opening position.

[0024] <Advantages> To summarize the above, the valve system 1 includes a tank 2 capable of storing a fluid, a pressure sensor 6 having a valve element 11 and detecting the internal pressure of the tank 2, a valve 4 for opening and closing the tank 2, a drive device for stroking the valve element 11 of the valve 4, and a control device 5. The control device 5 is configured to operate the drive device to continuously move the valve element 11, which is in a closed state, in the opening direction at a constant valve opening speed, and to store the position of the valve element 11 or stop the valve element 11 when the pressure sensor 6 detects that the internal pressure of the tank 2 has decreased by a predetermined amount, and to estimate an estimated open position S2 of the valve 4 based on the stored position or stop position S1 of the valve element 11 and the amount of opening of the valve element 11 until the internal pressure of the tank 2 decreases by a predetermined amount relative to the internal pressure before the valve opening. This configuration allows the open position of the valve 4 to be estimated more quickly than a method in which the valve element 11 is intermittently moved in the opening direction and whether or not the valve has opened each time is estimated.

[0025] In some embodiments, the control device 5 operates the drive device to continuously move the valve element 11, which is in a closed state, in the valve opening direction at a constant valve opening speed. When the pressure sensor 6 detects that the internal pressure of the tank 2 has decreased by a certain amount, the control device 5 stores the position of the valve element 11 or stops the valve element 11. The control device 5 determines the estimated open valve position S2 by subtracting from the stored or stopped position S1 of the valve element 11 a certain stroke amount equal to or greater than the valve opening amount required for the internal pressure of the tank 2 to decrease by a predetermined certain amount relative to the internal pressure before the valve opening. This configuration allows for a rough estimated open valve position S2 to be determined more quickly. Knowing the estimated open valve position S2, even if it is only a rough estimate, improves flow controllability compared to when the open valve position is completely unknown, and also enables the valve 4 to be set to an appropriate standby position S3.

[0026] The control device 5 is also configured to switch the valve opening speed of the valve 4 in accordance with the internal pressure before the tank 2 is opened so that the valve opening amount of the valve element 11 until the predetermined internal pressure decreases by a certain amount is equal to or less than a predetermined amount. With this configuration, the estimated valve opening position S2 can be estimated or determined with high accuracy without opening the valve 4 too much.

[0027] The driving device is a stepping motor 12. With this configuration, even when using a stepping motor 12 that is subject to large variations due to environmental conditions, part tolerances, etc., the estimated valve open position S2 of the valve 4 can be estimated or determined more quickly.

[0028] The control device 5 is also configured to set a position obtained by moving the valve 4 a predetermined amount in the valve closing direction from the estimated valve open position S2 as a standby position S3 of the valve 4. With this configuration, the valve 4 can be properly closed while maintaining its sealing performance even when subjected to external forces such as external vibrations.

[0029] <Other embodiments> The valve system described above can be applied not only to hydrogen fuel supply systems, but also to evaporated fuel treatment systems that include, for example, a fuel tank for storing automobile fuel, a canister for absorbing fuel vapor that evaporates from the fuel tank, and a vapor passage connecting the fuel tank and the canister. The valve system can also be widely applied to systems that include a tank for storing other fluids and a valve for opening and closing the tank.

[0030] In another embodiment, the driving device may be a linear solenoid, a DC motor, or the like, other than a stepping motor. Any other device may be used as long as it can electrically drive the valve element of the valve.

[0031] Although various embodiments have been described above, the present disclosure is not limited to these embodiments, and various other modifications, substitutions, improvements, and the like are possible for those skilled in the art. [Explanation of symbols]

[0032] 1 Valve System 2 Tanks 3 Supply route 3a Seat part 3b Upstream channel 3c downstream path 4 valves 5. Control device 6 Pressure Sensors 7. Supply destination 11 Valve body 12 Stepping motor 13 Output shaft 14 Sealing material P internal pressure ΔP judgment pressure S1 Stop position S1a Stop position S1b Stop position S2 Estimated valve opening position S3 Standby position

Claims

1. 1. A valve system comprising: a tank capable of storing a fluid; a pressure sensor for detecting an internal pressure of the tank; a valve having a valve body for opening and closing the tank; a drive device for stroking the valve body of the valve; and a control device; The control device The drive device is operated to continuously move the valve element in a closed state in a valve opening direction at a constant valve opening speed, When the pressure sensor detects that the internal pressure of the tank has decreased by a certain value, the position of the valve body is stored or the valve body is stopped. a valve system configured to estimate an opening position of the valve based on a stored position or stop position of the valve body and an amount of opening of the valve body until the internal pressure of the tank decreases by the predetermined value relative to the internal pressure before the valve is opened.

2. 1. A valve system comprising: a tank capable of storing a fluid; a pressure sensor for detecting an internal pressure of the tank; a valve having a valve body for opening and closing the tank; a drive device for stroking the valve body of the valve; and a control device; The control device The drive device is operated to continuously move the valve element in a closed state in a valve opening direction at a constant valve opening speed, When the pressure sensor detects that the internal pressure of the tank has decreased by a certain value, the position of the valve body is stored or the valve body is stopped. A valve system configured to consider a position obtained by subtracting a certain stroke amount equal to or greater than the valve opening amount of the valve body until the predetermined internal pressure of the tank decreases by a certain value compared to the internal pressure before the valve is opened from the stored position or stop position of the valve body as the open valve position.

3. 3. The valve system of claim 1 or claim 2, The control device is a valve system configured to switch the valve opening speed of the valve body in accordance with the internal pressure before the tank is opened so that the valve opening amount of the valve body until the predetermined internal pressure decreases by a certain value is equal to or less than a predetermined amount.

4. 3. The valve system of claim 1 or claim 2, The valve system, wherein the driving device is a stepping motor.

5. 3. The valve system of claim 1 or claim 2, The control device is configured to set a position obtained by moving the valve element a predetermined amount in a valve closing direction from the estimated valve open position as a standby position of the valve element.

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