JPH0435700B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention relates to an automatic pressure regulator that can be used to measure the flow characteristics of, for example, gas appliances or on-off valves used to control fluids. "Background of the Invention" For example, when measuring the flow characteristics of gas appliances or on-off valves, a known fluid pressure is applied to the test object, and the flow rate of the fluid at each fluid pressure is measured to determine the pressure-flow characteristics. . To carry out this measurement, a pressure generating means that can generate known pressure values over a wide range is required. ``Prior art'' For this reason, conventionally, gas pressure generated by an air pressure generating means is extracted through a control valve, and the opening degree of the control valve is controlled according to the pressure value to be applied to the test object. The pressure applied to the test object is changed, and the pressure-flow characteristics, etc. are measured by applying this pressure change to the test object. A device that applies a known pressure change to a test object in this way is generally called an automatic pressure regulator. FIG. 3 shows a conventional automatic pressure regulator. In the figure, numeral 1 indicates an air pressure generating means, and this air pressure generating means 1 may be, for example, either on the pressure side or the suction side of the compressor. The gas pressure generated by the pressure generating means 1 is transferred to the pipe 2.
is applied to the test object 4 via the control valve 3. Note that 11 is a manually operated valve, and 12 is a pressure indicator. These manually operated valve 11 and pressure indicator 12 are used to preset the gas pressure applied to the inlet side of the control valve 3 to a constant pressure value. The pressure of the gas applied to the test object 4 is measured by a measuring means 5, and the measured value is applied to a comparator 6. The comparator 6 compares the separately input target value 7 with the previously measured value, and outputs a deviation signal having the deviation value between the target value and the measured value to the output side of the comparator 6. This deviation signal is amplified by a servo amplifier constituting the control means 8 and drives the servo motor 9 to control the control valve 3. With this configuration, the gas pressure applied to the test object 4 is measured by the measuring means 5, and the measured value is compared with the target value 7, and the servo motor 9 controls the control valve 3 so that the deviation becomes zero. control, test object 4
is controlled so that the pressure value given to it is always maintained at the target value given from the outside. In order to change the pressure applied to the test object 4, it is sufficient to change the target value 7. In other words, by changing the target value 7, the control valve 3 changes its opening so that the measured value of the measuring means 5 becomes equal to the target value 7, and is controlled so that the target value 7 and the measured value are always in balance. be done. "Problems to be Solved by the Invention" When the target value 7 is changed in the conventional automatic pressure regulating device, the pressure value applied to the test object 4 changes in a direction that balances with the new target value. In this case, hunting is likely to occur because there is a delay between the movement of the control valve 3 and the actual change in gas pressure. In other words, if the response speed of the control valve 3 is increased, a transient response characteristic with hunting occurs as shown by curve A in FIG. 3, which has the disadvantage that it takes time for the pressure to stabilize. For this reason, it is possible to slow down the response speed of the control valve 3, but if the response speed of the control valve 3 is slowed down, the time T required for the pressure to reach the set value will become longer, as shown by curve B in Figure 3. Therefore, the time T required for the pressure to reach the set value is approximately the same as in the case of the transient response characteristic. In any case, when changing the pressure value applied to the test object 4, it takes a long time to stabilize to the changed target value, and the time required to test the characteristics of one test object becomes longer. There are drawbacks to this. For this reason, the pressure response characteristic is set to a transient response characteristic as shown by curve A in FIG. 3, and the control of the control valve 3 is stopped when the pressure measurement value approaches the new target value in this transient response characteristic. A method of controlling pressure to minimize excess pressure has been put into practice. However, even if control of the control valve 3 is stopped when the pressure value approaches the target value, it is difficult to stop the pressure value exactly at the target value. In other words, it is difficult to decide where to set the timing for stop control. However, there is a difference in the response time for pressure change between a state where the opening degree of the control valve 3 is small and a state where the opening degree is large. In other words, the time T required to reach the new target value tends to be shorter in the region where the opening degree of the control valve 3 is wide, and longer in the region where the opening degree of the control valve 3 is narrowed. For this reason, it is difficult to set the operating characteristics so that the pressure is exactly stable at the target value at any opening. The first purpose of this invention is to be able to stabilize the pressure value to a new target value in a short time when the target value is changed, and thereby to be able to measure the flow rate characteristics of the test object in a short time. Our goal is to provide an automatic pressure regulating device that can. A second object of the present invention is to provide an automatic pressure regulator that can obtain optimal response characteristics no matter where the opening degree of the control valve is. "Means for solving the problem" In the present invention, when changing the pressure value applied to the test object, a plurality of temporary setting values are provided between the newly set target value and the current pressure value, Control of the control valve is stopped for a certain period of time every time the pressure measurement value matches this provisional setting value. The values between the current pressure value and the temporary set value are set so that the values become gradually smaller as the measured pressure value approaches the target value. In this way, the temporary set value is gradually brought closer to the target value, and the pressure is made to match the target value in a short time. The present invention is further configured to vary the ratio between the current value and the temporary set value depending on the opening degree of the control valve, so as to obtain the optimum control characteristic depending on the opening degree of the control valve.
In other words, the ratio of the controlled amount up to the temporary set value is changed according to the opening degree of the control valve, and in the region where the control valve is throttled, the controlled amount up to the temporary set value is taken small, and the small controlled amount gradually reaches the target value. , and in a region where the control valve is open, the control amount up to the provisional set value is large. With this configuration, it is possible to always obtain the optimum control characteristics no matter what position the control valve is at, so the flow characteristics of the test object are as follows:
The flow rate characteristics of any flow rate characteristic can be measured in a short period of time, and therefore, there is an advantage that a large number of test objects can be tested in a short period of time. "Embodiment" FIG. 1 shows an embodiment of the present invention. In this figure, parts corresponding to those in FIG. 3 are designated by the same reference numerals. The features of this invention are the comparison means 6 (hereinafter referred to as the first comparison means) and the control means 8.
The point is that provisional set value generating means 13 is provided between the two. The temporary set value generating means 13 is a constant that outputs a constant of a ratio according to the deviation value when the deviation value between the target value 7 outputted from the first comparison means 6 and the current measured pressure value 10 is given. a storage means 14; a calculation means 15 for multiplying the constant read from the constant storage means 14 by the deviation value given from the first comparison means 6 and outputting a temporary setting value 21; and a temporary setting calculated by the calculation means 15. A second comparison means 17 calculates the deviation between the value 21 and the pressure measurement value 10. Every time the comparison result of the second comparison means 17 becomes zero, a calculation command signal is given to the calculation means 15 to determine the next provisional setting value. arithmetic control means 16 for calculating the value of
and a switching means 19 which is controlled by the control output of the stop control means 18 and provides a stop control signal to the control means 8. The constant storage means 14 can be constituted by, for example, a read-only memory. The constant storage means 14 stores the target value 7 and the measured value 1 from the first comparison means 6.
By giving a deviation value between 0 and 0, a constant having a ratio corresponding to the deviation value is read out. The constant storage means 14 and the calculation means 15 can be constructed by digital circuits. Therefore, the deviation signal output from the first comparing means 6 is transmitted to the AD converter 2.
2 into a digital signal, and the digital conversion output is applied to constant storage means 14 and calculation means 15. In addition, a DA converter 23 is connected to the output side of the calculation means 15.
is provided, and the tentative setting value obtained by calculation is converted into an analog signal and provided to the second comparing means 17. On the other hand, the control valve 3 is provided with an opening detection means 24, and the detected output of the opening detection means 24 is stored in the constant storage means 14.
is given, and a constant readout area is selected according to the opening degree of the control valve 3. It is assumed that the opening detection means 24 is a detector that outputs its detection output as a digital signal. As an example, the opening degree of the control valve 3 is divided into 10 areas between fully closed and fully open, and a constant corresponding to the deviation value is set for each divided area. An example is shown below.

[Table] By defining the readout area of the deviation value A according to the opening degree of the control valve 3 and giving the deviation value in each opening area, a constant with a ratio corresponding to the deviation value can be obtained. can be read out. As is clear from the above example, the smaller the opening, the smaller the constant is set, the smaller the deviation between the temporary setting value and the current value, and the smaller the control amount per step, which reduces the delay in response. We are trying to reduce the amount of excess that occurs. On the other hand, when the opening degree is large, the response is faster than when the opening degree is small, so a large constant is used to increase the one-step control amount. The constant read from the constant storage means 14 is stored in the calculation means 1.
5, and the calculation means 15 multiplies the deviation value given from the first comparison means 6 by a constant to calculate a provisional setting value. The provisional set value is given to the second comparing means 17, and the second comparing means 17 compares the measured value 10 given from the measuring means 5 with the provisional set value to obtain a deviation value. The deviation signal outputted from the second comparison means 17 is given to the control means 8 through the switching means 19, and is amplified by the control means 8 to drive the servo motor 9 and control the opening degree of the control valve 3. By controlling the opening degree of the control valve 3, the measured value of the measuring means 5 approaches and matches the first provisional set value. In this matched state, the output of the second comparing means 17 becomes zero. When the stop control means 18 detects that the output of the second comparison means 17 has reached the zero state, the stop control means 18 switches the switching means 19.
is switched to the ground potential side, and the ground potential is applied to the control means 8. As a result, the control means 8 then controls the second comparison means 17.
Even if a deviation occurs due to excessive pressure response delay, the servo motor 9 is prevented from driving, the opening degree of the control valve 3 is maintained at a constant position, and hunting is prevented from occurring. While the stop control means 18 prevents the servo motor 9 from being driven, the arithmetic control means 16 controls the arithmetic means 15.
Give a calculation command signal to calculate the next provisional setting value. In this state, since the measured value of the measuring means 5 has reached the first provisional setting value from the initial value, the deviation value between the measured value and the target value 7 is smaller than the previous value. Therefore, in accordance with this deviation value, the constant read out from the constant storage means 14 is multiplied by the deviation value outputted from the first comparison means 6 to calculate the second provisional setting value. In this way, each time the measured value 10 of the measuring means 5 matches the temporary set value, the servo motor 9 is stopped for a certain period of time, for example, for several seconds, and the temporary set value is gradually changed to a smaller value. , at each provisional setting value, the amount of excess pressure gradually decreases and approaches the target value. "Effects of the Invention" As explained above, according to the present invention, when changing a target value, a plurality of temporary set values are provided between the target value and the current pressure value, and one step of the temporary set value is changed. Since the constant was determined so that the amount of change in pressure gradually decreases according to the deviation value from the target value, even if there is an excess of pressure at each temporary setting value, the amount of excess will gradually decrease and approach the target value. At this time, the amount of excess pressure value becomes sufficiently small. Therefore, by taking the rate of change in pressure between the initial value and the first provisional setting value and at each provisional setting value as the rate of change of the transient response characteristic, even if an overshoot occurs at each provisional setting value, measurement 10 will reach the target value. The amount of overshoot gradually decreases as it approaches the target value, and when it matches the target value, the amount of overshoot can be made sufficiently small. Therefore, the pressure value can be made to match the desired target value in a short time. Furthermore, in this invention, the constant is changed according to the opening degree of the control valve 3, and the ratio for determining the provisional setting value is changed, so that the optimum control state can be maintained no matter where the opening degree of the control valve 3 is. I can do things. Therefore, according to the present invention, gas pressure having a target pressure value can be applied to the test object 4 one after another in a short time, and the opening degree of the control valve, that is, the flow rate of the gas passing through the test object 4 can be controlled. Regardless of the flow rate range, pressure changes will follow the set value in a short time when the set value is changed, so the flow characteristics of the test object that handles any flow rate can be measured in a short time. You can get real benefits by being able to do things. Incidentally, in the above-described embodiment, a case has been described in which the temporary set value generating means 13 is constructed of blocks for each component, but this portion can also be replaced with a microcomputer. In the above description, a case has been described in which four temporary setting values are provided between the initial position and the setting value, but it is easy to understand that there is no limit to the number of temporary settings. Furthermore, in the above description, a case has been described in which the pressure of the gas applied to the test object 4 is measured, and the deviation from the target value 7 and the deviation from the provisional setting value are calculated based on the measured pressure value. It can be configured to measure the flow rate of gas applied to the test object 4 and perform control based on this gas flow rate.

[Brief explanation of drawings]

FIG. 1 is a block diagram for explaining one embodiment of the present invention, FIG. 2 is a graph for explaining the operation of the present invention, FIG. 3 is a block diagram for explaining the conventional technique, and FIG. The figure is a graph for explaining the drawbacks of the conventional technology. 1: Air pressure generating means, 2: Piping, 3: Control valve,
4: Test object, 5: Measuring means, 6: First comparison means, 7: Target value, 8: Control means, 9: Servo motor, 10: Measured value, 11: Manual valve, 12: Pressure indicator, 13 : Temporary setting value generation means, 14: Constant storage means, 15: Calculation means, 16: Calculation control means,
17: Second comparison means, 18: Stop control means, 1
9: Switching means, 21: Temporary setting value signal, 22: AD
Converter, 23: DA converter.

Claims (1)

[Scope of Claims] 1. A test object to which air pressure generated by the air pressure generating means is applied and through which the given gas passes; B. A test object inserted between the air pressure generating means and the test object. a control means for controlling the flow rate of gas flowing through the body (or the pressure of gas applied to the test object); A measuring means for measuring D, a first comparing means for comparing the measured value of this measuring means with a target value, and E having a predetermined value according to the deviation value obtained as a comparison result of this first comparing means. a constant storage means for outputting a constant; F a calculation means for calculating a temporary setting value by multiplying the constant output from the constant storage means by the deviation value output from the first comparison means; G measurement of the measurement means. a second comparison means for determining the deviation between the value and the provisional setting value; H a control means for controlling the opening degree of the control valve in a direction in which the comparative output of the second comparison means approaches zero; I this control a calculation control means for causing the calculation means to sequentially calculate a second, third, . . . temporary setting value each time the measured value matches the temporary setting value by control of the means; Therefore, an automatic pressure regulating device comprising: stop control means for temporarily stopping the control of the control means every time the measured value matches a provisional setting value.