JP5636563B2 - Digital soil physical property measuring device - Google Patents

Description

  The present invention relates to an apparatus for collecting measurement data by converting a measurement of a physical quantity related to a three-phase structure of soil into digital using a soil sample that retains a structure in a natural state.

  Soil is a three-phase material composed of a solid phase, a liquid phase and a gas phase. The solid phase is composed of minerals and minerals, mainly minerals, and the liquid phase and gas phase are composed of soil moisture and soil air, respectively. The volume ratio occupied by each of the solid phase, liquid phase, and gas phase is the three-phase distribution of the soil. The proper relationship between the three phases of soil is the decisive factor in soil fertility and crop growth, and knowing the three-phase distribution is fundamental to soil diagnosis.

  The actual volume measurement method is used as a method for measuring soil samples while maintaining the structure in the natural state. The total volume of the soil and the volume of each of the three phases of the solid phase, liquid phase, and gas phase can be expressed by the following equations.

  Vt = Vs + Vl + Va (Vt = total volume, Vs = solid phase, Vl = liquid phase, Va = gas phase)

  The actual volume measured using the actual volume measuring method is the sum of the solid phase volume and the liquid phase (water) volume of the soil, and can be expressed by the following equation.

  V = Vs + Vl = Vt−Va (V = actual volume, Vs = solid phase, Vl = liquid phase, Vt = total volume, Va = gas phase)

  At this time, the relationship between the total weight of the soil, the three-phase solid phase weight, the liquid phase (water) weight, and the vapor phase weight of the soil can be expressed by the following equation.

  W = S + M + Aw (W = total weight, S = solid phase weight, M = liquid phase (water) weight, Aw = gas phase weight)

  However, since the gas phase weight Aw is normally regarded as 0, the total weight is the sum of the solid phase weight and the liquid phase (water) weight and can be expressed by the following equation.

  W = S + M (W = total weight, S = solid phase weight, M = liquid phase (moisture weight))

  In the actual volume measurement method, the total weight of the soil to be measured and the sample for which the actual volume has been measured are dry-heated to remove moisture, and the weight lost thereby is defined as the liquid phase (moisture) weight. At this time, the density of the soil water is 1 g / cm 3, and the soil liquid phase (water) weight and the liquid phase (water) volume have the same numerical value. Therefore, the solid phase volume of the soil is a volume amount obtained by subtracting the liquid phase (water) volume from the actual volume and can be expressed by the following equation.

  Vs = VM (Vs = solid volume, V = actual volume, Vl = liquid phase (water) volume

  That is, in the actual volume measurement method, when the actual volume of the soil collected in a soil collection container with a known capacity is measured, the gas phase volume is obtained. Then, the solid phase volume and the liquid phase (moisture) volume can be obtained by drying the sample after the measurement of the actual volume to remove the moisture.

  Conventionally, when measuring the volume of each of the three phases of the soil (solid phase, liquid phase, gas phase), a method of collecting a soil sample while maintaining the soil structure in the natural state, and measuring to measure the actual volume Methods are established and widely used. Generally, agricultural soil is collected using a 100 ml metal cylindrical container. This is based on the idea of the National Institute of Agricultural Mechanics, and adopting a container with a total volume of 100 ml is advantageous in that the collected soil can be used for actual volume measurement as it is.

According to Boyle-Charles' law, when a volume change occurs in one air system when the temperature is constant, the following equation holds for the pressure change associated therewith.

  This equation shows that if the initial pressure is made constant (for example, atmospheric pressure) and the pressure change amount is made constant, the air volume and the volume change amount are in a proportional relationship. The measuring instrument for determining the actual volume of the soil employs a method of determining the actual volume from the amount of change in volume when compressing to a specific target pressure by making the initial pressure constant using this principle. This actual volume measuring device performs a compression operation until a target pressure is reached using an air cylinder after putting a soil sample in a sealed container. The actual volume is measured by obtaining the volume change amount from the piston movement amount of the air cylinder at that time (see Patent Document 1).

Published Utility Showa 59-006772

  When the conventional actual volume measuring device is compressed to the target pressure with an air cylinder, the pressure applied to the small air layer between the soil particles, so-called pores in the soil, is steady due to the characteristics of the soil structure. Fluctuations occur in the pressure change in the sealed container.

  At that time, the measurer must perform the compression operation until the target pressure is gradually reached while observing the pressure measurement value in the sample container. Since this series of compression operations is performed manually, individual differences are likely to occur in the compression operation by the measurer, causing measurement errors.

  Even if the apparatus itself deteriorates over time or has some kind of failure, if the error is small, the measurer may not be able to recognize it. This also increases the measurement error.

  In addition, in order to improve the measurement accuracy, the same sample is measured about 4 to 5 times and the average value is obtained to obtain the measurement result. However, when the number of measurement samples increases, a lot of labor is required for measurement work and measurement value calculation. Become.

  The present invention has been made in view of the above problems, and an object thereof is to provide a digital soil physical property measuring apparatus that automatically realizes high-accuracy real volume measurement.

  The above-mentioned object is achieved by the following means based on the earnest research of the present inventors.

That is, the present invention that achieves the above object includes a measurement sample chamber, a pressurizing unit that pressurizes the sample chamber, a pressure measuring unit that measures the pressure in the sample chamber, and an actuator that drives the pressurizing unit. A pressure means driving device, a control device for controlling the pressure means driving device, and a display unit for presenting information to a user, the control device until the sample chamber reaches a target pressure. The actual volume calculation means for calculating the sample volume in the sample chamber based on the required air flow rate or the pressure change obtained when the target flow rate is fed into the sample chamber, and the sample volume The pressure obtained when the calibration space having a different known volume is pressurized by the pressurizing means, and the air flow rate until the calibration space reaches the target pressure, or the target flow rate is sent to the calibration space. Auto calculation of change Calibration means, and the actual volume calculation means calculates the sample volume using the air flow rate or the pressure change calculated by the automatic calibration means, and the pressurization means is a cylinder And a piston that moves in the cylinder, and the automatic calibration means includes a sample chamber side pipe that communicates the cylinder and the sample chamber, and a sample chamber side valve that opens and closes the sample chamber side pipe. A calibration chamber that forms the calibration space, a calibration chamber side piping that communicates the cylinder and the calibration chamber, a calibration chamber side valve that opens and closes the calibration chamber side piping, the sample chamber side valve, and the calibration chamber A valve operating unit that opens and closes a side pipe, and the valve operating unit includes a first state in which only the cylinder and the sample chamber communicate with each other among the cylinder, the sample chamber, and the calibration chamber; Cylinder, sample And only the cylinder and the calibration chamber to each other out of the calibration chamber and switches between a second state communicating.

The calibration chamber communicates with the sample chamber via a first calibration chamber side pipe and communicates with the sample chamber via a second calibration chamber side pipe. A second calibration space different from the volume of the space, wherein the automatic calibration means includes a first calibration chamber side valve for opening and closing the first calibration chamber side piping, and the second calibration chamber. It is preferable to have a second calibration chamber side valve that opens and closes the side pipe and a calibration chamber side valve control unit that individually performs opening and closing operations of the first and second calibration chamber side valves.

The calibration space can be switched between a volume V1 and a volume V2 that is different from the volume V1, and the automatic calibration means is configured to allow the air flow rate or the pressure related to the calibration space in the state of the volume V1. It is preferable to calculate a change amount and calculate the air flow rate or the pressure change amount related to the calibration space in the state of the volume V2.

  The control device can be switched between a state in which the moving speed of the piston in the cylinder is a speed V1 and a state in which the moving speed of the piston in the cylinder is a speed V2 smaller than the speed V1. It is preferable that

When the pressure in the sample chamber is smaller than a threshold value, the control device sets the moving speed of the piston in the cylinder to a speed V1, and when the pressure in the sample chamber is equal to or higher than the threshold value, The moving speed of the piston is preferably a speed V2.

  Since the present invention automates and controls a series of measurement operations that pressurize until the target pressure is reached while measuring the pressure in the sample chamber, it is possible to prevent measurement errors due to individual differences in the measurement method of the measurer. Accuracy is improved. Furthermore, according to the present invention, calibration processing can be automatically performed in accordance with the measurement environment (temperature, humidity, pressure), so that the measurement accuracy can be increased. In particular, when the calibration amount (difference from the ideal value) is large during calibration processing, it is possible to detect a mechanical abnormality beforehand by displaying an error.

  Further, according to the present invention, when the pressurizing unit pressurizes to a specific end point at the time of calibration or actual measurement, it is forcibly terminated, so that it is possible to prevent damage to the apparatus.

It is an external view of a digital soil physical property measuring apparatus. It is a top view of a digital soil physical property measuring device. It is a rear view of a digital soil physical property measuring device. It is a block diagram which shows the connection state of a digital soil physical property measuring apparatus. It is a block diagram which shows the function of a digital soil physical property measuring apparatus. It is a block diagram which shows operation | movement of the calibration work of a digital soil physical property measuring apparatus. It is a block diagram which shows the other structure of a digital soil physical property measuring apparatus. It is a block diagram which shows the other structure of a digital soil physical property measuring apparatus.

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

  The digital soil physical property measuring apparatus 1 is shown by FIGS. 1-3. The digital soil physical property measuring apparatus 1 includes an operation panel 3 for inputting items necessary for measurement, a display unit 5 for displaying operation procedures and measurement results, a sample chamber 11 for storing a sample to be measured, and electric power necessary for measurement. , A power switch 9 for energizing or cutting off the supplied power, an output connector 15 for digitally outputting measurement data, an input connector 17 for inputting a measurement control program 130 (not shown), It is comprised with the housing | casing 7 which attached these.

  Next, the internal mechanism and connection state of the housing 7 of the digital soil physical property measuring apparatus 1 will be described with reference to FIG. Inside the housing 7, an air cylinder 23 having an air outlet 29, a piston 27 that pressurizes the air 25 in the air cylinder 23, a gear 33 attached to the piston 27, and a gear 35 that drives the gear 33 are attached. A motor 37, an origin sensor 39 for detecting the initial position of the piston 27, and a pressure sensor 31 for measuring the pressure of the air 25. When the gear 35 is rotated by the motor 37, the gear 33 reciprocates due to the rack and pinion structure, and the piston 27 is driven. The air 25 of the air cylinder 23 is pressurized or depressurized by the piston 27.

  The inside of the housing 7 further includes an electromagnetic valve 41 that opens and closes the air cylinder 23 and the air 25 to and from the sample chamber 11, an air outlet 29 of the air cylinder 23, the sample chamber 11, the pressure sensor 31, and the electromagnetic valve 41. And a joint 45 for branching and connecting the pipe 43. The solenoid valve 41 functions as a so-called relief valve. When the solenoid valve 41 is opened, the inside of the pipe 43 is opened to the atmosphere side. On the other hand, when the electromagnetic valve 41 is closed, the inside of the pipe 43 becomes a sealed space, so that the pressure of the air 25 in the air cylinder 23 is transmitted to the sample chamber 11 through the pipe 43.

  Further, the control device 21 and the power socket 13 are disposed inside the housing 7, and an adapter 55 having a power cable 57 is disposed outside the housing 7. The control device 21 is connected to the motor 37, the origin sensor 39, the pressure sensor 31, the electromagnetic valve 41, the operation panel 3, the display unit 5, and the power socket 13 using the wiring 47. The adapter 55 is connected to the power socket 13 and converts the voltage of the supplied power for the control device 21. Accordingly, the power supply 13 receives supply of all power necessary for controlling the digital soil physical property measuring apparatus 1 from the adapter 55. Any power supply necessary for the control may be used as long as it matches the specification of the control device 21. For example, a storage battery 59 can be used.

  The control device 21 has a microprocessor (CPU) 49, a measurement control program 130, a storage unit (ROM) 51 having measurement data, and a function of keeping the current date and time even if the set date and time are turned off. A real-time clock 53, an output connector 15, and an input connector 17 are provided. An output cable 62 for digitally outputting the measurement data to the external computer 61 is connected to the output connector 15. An input cable 64 for inputting the measurement control program 130 from the host computer 63 is connected to the input connector 17.

  Next, the function of the digital soil physical property measuring apparatus 1 will be described with reference to FIG. The digital soil physical property measuring apparatus 1 includes a measurement sample chamber 11, a pressurizing means 65 for pressurizing the sample chamber 11, a pressure measuring means 67 for measuring the pressure in the sample chamber 11, and air used for pressurization. A flow rate measuring means 69 for measuring the flow rate, a pressurizing means driving device 71 for driving the pressurizing means 65, and a control device 21 for controlling the pressurizing means driving device 71 based on the internal pressure of the sample chamber 11 are provided.

  The correspondence between FIG. 4 and FIG. 5 will be described. The pressurizing means 65 in FIG. 5 corresponds to the 23 air cylinder, the air 25, the piston 27, and the air outlet 29 in FIG. 4. The pressure measuring means 67 in FIG. 5 corresponds to the pressure sensor 31 and the wiring 47 in FIG. 5 corresponds to the gear 33, the gear 35, the motor 37, the origin sensor 39, and the wiring 47 in FIG. The pressurizing control unit 101 to the origin processing unit 123 in FIG. 5 are realized by executing a program stored in the storage unit (ROM) 51 in FIG. This is a function for controlling the operation of the digital soil physical property measuring apparatus 1.

  With reference to FIG. 5, the control device 21 is configured to realize various functions by the measurement control program 130 being executed by the CPU 49. Specifically, the control device 21 includes, as its functional configuration, a pressurization control unit 101, a pressurization stop unit 103, a transition determination unit 105, an average value calculation unit 107, an iterative unit 109, an output unit 111, a measurement value storage unit 113, Automatic calibration means 115, error notification means 117, actual volume calculation means 119, forced termination means 121, and origin processing means 123 are provided.

  Note that a computer program for realizing these functions (pressurization control means 101 to origin processing means 123) is a storage unit (ROM) provided in the control device 21 via the input connector 17 on the back surface of the housing 7. 51 has been transferred in advance. The program stored in the storage unit (ROM) 51 is executed by the microprocessor 49 provided in the control device 21 while calculating input / output signals. The program stored in the storage unit (ROM) 51 is not erased from the storage unit (ROM) 51 even when the supply of power is stopped. That is, after the transfer operation is performed once, it is not necessary to transfer the program from the outside, and the program can be executed at any time. Furthermore, when it is necessary to modify the program, the modified program may be transferred to the storage unit (ROM) 51 via the input connector 17, so that the program can be updated in a short time without disassembling the housing 7. Can do. Moreover, the control apparatus 21 is provided with the function to display an operation procedure and a measurement result on the display part 5 based on the command of a program.

  The pressurization control unit 101 controls driving of the pressurization unit driving device 71. Further, the driving speed can be controlled. The driving speed can be set to be constant or can be set to change from high speed to low speed.

  For example, the pressurization control means 101 has a first speed for pressurizing the sample chamber 11 containing the sample from the initial (atmospheric pressure) to a constant intermediate pressure (for example, 30 kPa), and from the intermediate pressure to a target pressure (for example, 36 kPa). It is preferable to control the driving speed of the pressurizing means driving device 71 by the second speed at which the pressure is applied. At this time, the second speed is set to be slower than the first speed. Of course, it may be controlled at a constant speed from the beginning until the target pressure is reached.

  The pressurization stop unit 103 stops or stops pressurization by the pressurization unit driving device 71 according to the purpose. The pressurization is stopped mainly when (1) when the sample chamber 11 reaches a target pressure during measurement or calibration, and (2) when the pressurization is performed at two speeds as described above. When the chamber 11 reaches an intermediate pressure (when the speed is switched), (3) pressurization may be stopped due to some error.

  In the case of (1) above, the pressure in the sample chamber 11 is detected by the pressure sensor 31, and the pressurization is stopped at the same time that the pressure reaches the target pressure. In the case of the above (2), for example, when the inside of the sample chamber 11 reaches the intermediate pressure from the initial stage by the pressurization control means 101, pressurization is temporarily interrupted. In the case of (3), when an error occurs during measurement, pressurization is stopped in order to avoid destruction of the digital soil physical property measuring apparatus 1. In any case, the pressurization stop means 103 stops and interrupts the drive of the pressurization means drive device 71.

  In addition, although the case where pressurization was stopped by stopping / interrupting the driving of the pressurizing means driving device 71 was shown here, the inside of the pipe 43 is opened to the atmosphere side by opening the electromagnetic valve 41, and as a result The pressurization may be stopped as follows.

  When the pressurization is temporarily interrupted by the pressurization stop unit 103, the transition determination unit 105 determines whether or not to perform further pressurization. For example, when pressurization is interrupted at the intermediate pressure, the amount of pressure change in the sample chamber 11 is detected, and the next pressurization (intermediate pressure to target pressure) is shifted based on the fluctuation. It is determined whether or not. In this way, by further stopping the pressurization during the pressurization and performing the transition determination, finer control can be performed.

  Specifically, when the transition determination unit 105 detects a pressure drop of a certain amount or more at the intermediate pressure, the shift determination unit 105 stops the measurement without further pressurization. On the other hand, when a pressure drop of a certain amount or more is not detected, pressurization into the sample chamber 11 is resumed. Specifically, the transition determination unit 105 issues a transition instruction to the pressure control unit 101. The pressurization control means 101 that has received the transfer instruction controls the pressurization means driving device 71 at the second speed. As a result, the inside of the sample chamber 11 is pressurized from the intermediate pressure to the target pressure.

  The actual volume calculation means 119 moves the piston 27 until the pressure in the sample chamber 11 (pipe 43) reaches the target pressure, that is, the movement amount of the piston 27 that has reached the target pressure and is stopped by the pressurization stop means 103. Is detected, the amount of air required for pressurization is calculated, and the actual volume of the soil in the sample chamber 11 is calculated based on Boyle-Charles' law. The movement amount of the piston 27 can be calculated by detecting the rotation amount of the gear 35 and the motor 37.

  The measured value storage unit 113 stores information such as the actual volume measured by the actual volume calculation unit 119 in a predetermined storage area of a RAM (not shown).

  The average value calculating unit 107 repeatedly measures the actual volume calculating unit 119 a plurality of times (for example, three times), and calculates the average value using the measured values for the plurality of times (for example, three times). As a result, minute measurement errors can be made uniform. This is because the microprocessor 49 of the control device 21 uses the measurement value storage means 113 to call the measurement values stored in the RAM a plurality of times, and the average value calculation means 107 calculates the average value. Realized.

  In addition, although the case where the measurement is performed three times and the average value is calculated is shown here, it is also preferable to flexibly change the number of measurements. For example, the repeating unit 109 preferably compares the previous measurement value with the current measurement value and repeats the measurement until the difference falls within a certain range. When the measurement error is large, the repeating unit 109 automatically repeats the measurement until the error becomes small. The average value calculation means 107 can calculate the average value by using a plurality of continuous measurement values with the smallest error within the repeatedly measured range. Note that the repetition means 109 compares, for example, three measurements before and after, and if the difference between the measured values does not fall within a certain range, the pressurization stop means 103 stops the pressurization, which will be described later. The error notification unit 117 displays an error on the display unit 5 and ends the process.

  The output unit 111 outputs the measurement value stored in the RAM by the measurement value storage unit 113 (hereinafter also referred to as measurement data) to the external host computer via the output connector 15.

  The forcible end means 121 always determines whether or not the movement amount of the piston 27 exceeds the maximum allowable value Rmax (see FIG. 6) that is a specific end point. This maximum permissible value Rmax is slightly larger than the movement amount of the piston 27 (0 ml ideal movement amount R described later) necessary for raising the sample chamber 11 to the target pressure when the inside of the sample chamber 11 is empty. Value. That is, as long as the measurement is performed by the apparatus 1 without any trouble, the piston 27 cannot be considered to move to the maximum allowable value Rmax. Therefore, when the piston 27 exceeds the maximum allowable value Rmax, the forced termination unit 121 instructs the pressurization stop unit 103 to stop the pressurization by the pressurization unit driving device 71. At this time, the error notification unit 117 is instructed to display an error by the display unit 5.

  For example, if the lid of the sample chamber 11 is loose or the pipe 43 is detached and air is gradually leaking, the amount of movement of the piston 27 before the sample rate 11 reaches the target pressure is the maximum allowable value. Rmax is reached. In this case, in the present apparatus 1, the piston 27 is forcibly stopped by the forcible ending means 121, so that the destruction of the piston 27 can be prevented in advance. If the piston 27 is pushed to the mechanical upper limit by the motor 37, the piston 27 is deformed, the gear 33 or the gear 35 is damaged or deformed, or an excessive load is applied to the motor 37. Measurement errors of the apparatus 1 are likely to occur. Therefore, the forced termination means 121 reduces the maintenance burden on the apparatus 1 and enables stable use over a long period of time.

  The origin processing means 123 sets the origin of the pressurizing means 65 (piston 27). Specifically, based on the electrical signal from the origin sensor 39, the motor 37 is driven to move the gear 33 attached to the piston 27 to a specific start point (origin). Thereafter, the electromagnetic valve 41 is opened to make the pressure of the air 25 in the air cylinder 23 equal to the atmospheric pressure, and this is confirmed by the pressure sensor 31 measuring it. That is, it is determined whether or not there is a certain pressure difference between the pressure of the air 25 and the atmospheric pressure. If the pressure difference is within a certain range, it is determined that the origin setting has been completed normally. On the other hand, if the pressure difference exceeds a certain level, there is a problem such as clogging somewhere in the air system, or the pressure sensor 31, the origin sensor 39, the motor 37, the piston 27, the gear 33, the gear 35, the control device 21. It is determined that there is a possibility that a failure has occurred. Therefore, in this case, an error message is displayed on the display unit 5 to notify the user of the abnormality of the apparatus 1 in advance.

  The error notification unit 117 displays various error messages on the display unit 5 in response to instructions from other various units. In addition, although the case where a text is displayed as an error message is shown here, any means that can convey an error to the user, such as display by a lamp or voice guidance, may be adopted as appropriate. .

  The automatic calibration means 115 is for performing automatic calibration of the digital soil physical property measuring apparatus 1. Specifically, the automatic calibration unit 115 includes a calibration volume setting unit 115A, an allowable error storage unit 115B, and a calibration processing unit 115C.

  As shown in FIG. 6, the calibration volume setting unit 115 </ b> A stores information related to the volume of the calibration sample (hereinafter referred to as calibration volume) input from the operation panel 3 in the storage unit (ROM) 51. This calibration volume means the volume of the calibration sample accommodated in the sample chamber 11. For example, in this embodiment, two types of calibration samples (test pieces) of 30 ml and 50 ml are prepared. Therefore, four types of calibration volumes of 0ml (no calibration sample), 30ml, 50ml, and 80ml (30ml calibration sample and 50ml calibration sample set at the same time) are selected as calibration volumes that can be used as calibration values. it can. In this apparatus 1, the calibration volume setting unit 115A recognizes which calibration volume is used for calibration.

  From the viewpoint of the calibration space, this embodiment means a space remaining in the sample chamber 11. That is, in this embodiment, by using the sample chamber 11 and setting a calibration sample therein, the calibration space is changed from the normal state (−0 ml) to −30 ml, −50 ml, and −80 ml. It can be changed appropriately at each stage.

  The permissible error storage unit 115B corresponds to each calibration volume, information on the ideal movement amount (theoretical value) R of the pressurizing means 65 (piston 27) required to achieve the target pressure, and this ideal movement. Information relating to the allowable error before and after the allowable amount R (allowable upper limit moving amount RU and allowable lower limit moving amount RD) is stored in the storage unit (ROM) 51.

  The calibration processing unit 115C performs automatic calibration processing based on a user start instruction. Specifically, the pressure control means 101 is used to pressurize the sample chamber 11 until the target pressure is reached, and the actual movement amount T of the piston 27 stopped by the pressure stop means 103 is detected. The actual movement amount T and the calibration volume are set as a set and stored in the storage unit (ROM) 51 as calibration information. In this embodiment, this calibration operation is executed in the order of 80 ml, 50 ml, and 30 ml, and this is repeated twice to calculate six sets of calibration information. Based on the six sets of calibration information, a calculation formula used in the actual measurement of the digital soil physical property measuring apparatus 1 is determined (calibrated). This calculation formula is used at the time of actual measurement by the actual volume calculation means 119. As a result, highly accurate calibration work is realized in accordance with various measurement environment changes such as temperature change and atmospheric pressure change, and the measurement accuracy can be increased.

  In addition, the calibration processing unit 115C determines whether or not the actual movement amount T in the calibration work deviates from the allowable upper limit movement amount RU and the allowable lower limit movement amount RD that are allowable errors. When the actual movement amount T exceeds the allowable error, the automatic calibration unit 115 instructs the error notification unit 117 to display an error on the display unit 5. By this error display, for example, when the calibration volume set by the user and the calibration sample actually stored in the sample chamber 11 are different, or when the middle of the pipe 43 is clogged, etc. Trouble can be automatically detected. That is, according to the calibration processing unit 115C, it is possible to automatically determine whether the error should be adopted as calibration information or an error caused by a mechanical trouble based on the magnitude of the error. Calibration processing can be suppressed. In addition, since mechanical troubles of the apparatus 1 can be detected during calibration work that is always performed before actual measurement, damage to the apparatus 1 can be prevented and errors during actual measurement can be reduced.

  Even during the calibration work, the forcible ending means 121 always determines whether or not the movement amount of the piston 27 exceeds the maximum allowable value Rmax. Even during calibration, if the lid of the sample chamber 11 is loose, the pipe 43 is disconnected, or the solenoid valve 41 is broken, the piston 27 may reach the maximum allowable value Rmax before reaching the target pressure. is there. Therefore, if the forced termination means 121 is always functioned, the apparatus 1 can be prevented from being damaged during the calibration work.

  Even during this calibration work, the origin processing means 123 sets the origin of the pressurizing means 65 (piston 27) before starting. As a result, even before the calibration work, it is possible to detect in advance some trouble that has occurred in the apparatus 1, and it is possible to suppress a calibration error.

  Next, the measurement procedure of the digital soil physical property measuring apparatus 1 will be described with reference to FIG. First, in order to supply power necessary for driving the digital soil physical property measuring apparatus 1, a power cable 57 and, in the case of a commercial power supply, a voltage conversion adapter are connected to the power socket 13. When measuring in a place without a commercial power supply, a storage battery 59 is connected. Next, the power switch 9 (see FIG. 3) is turned on to energize the digital soil physical property measuring apparatus 1.

  Next, before measuring the soil, the digital soil physical property measuring apparatus 1 accommodates the calibration sample in the sample chamber 11 and performs the calibration work. The calibration sample is a cylindrical body having a known volume (for example, 30 ml, 50 ml). In the calibration work, a calibration sample is put in the sample chamber 11 and sealed, and the total volume (30 ml, 50 ml, 80 ml) of the calibration sample is selected and input on the operation panel 3 while viewing the display unit 5, and the start button is pressed. Start with that.

  Calibration is automatically performed by the automatic calibration means 115 of the control device 21. The automatic calibration will be specifically described. First, the motor 37 is driven on the basis of the electric signal of the origin sensor 39 shown in FIG. 4 to move the gear 33 attached to the piston 27 to a specific start point (origin). Move to and stop. Next, the electromagnetic valve 41 is opened, the air 25 in the air cylinder 23 is released to the atmosphere, and it is confirmed by the pressure sensor 31 whether or not the atmosphere is normally released. Specifically, the pressure sensor 31 measures the pressure of one air system composed of the air cylinder 23, the solenoid valve 41, the piping 43, the joint 45, and the air outlet 29, and the electrical signal of the pressure sensor 31 is wired 47. Is transmitted to the control device 21. The origin processing unit 115D of the control device 21 performs arithmetic processing on the signal to determine whether there is a difference between the pressure of the air 25 of the air cylinder 23 and the atmospheric pressure.

  If there is a certain pressure difference between the air 25 and the atmospheric pressure at this time, there is a problem such as clogging somewhere in the air system, or the pressure sensor 31, the origin sensor 39, the motor 37, the piston 27. There is a possibility that a failure has occurred in the gear 33, the gear 35, and the control device 21. Therefore, an error message is displayed on the display unit 5 to inform the user of an abnormality of the apparatus 1.

  Here, although 30 ml and 50 ml are exemplified as the calibration samples, any volume may be used as long as it is within the measurement range. Since the calibration sample is made of a material and shape that is less likely to change in volume due to compression or temperature change, a metal cylindrical shape is usually used. However, other shapes and materials may be used.

  Next, when the origin setting is completed normally, the electromagnetic valve 41 is closed and the sample chamber 11 is pressurized until the target pressure is reached. This pressurization is performed by driving the motor 37 until the target pressure is reached while calculating the electrical signal from the pressure sensor 31 by the microprocessor 49. That is, by rotating the gear 35 attached to the motor 37, the piston 27 and the gear 33 are moved so that the air 25 in the air cylinder 23 is sent to the sample chamber 11. At this time, since the above air system is sealed, the air in the air system is compressed and the pressure rises. The speed at which the air in the air system is compressed is, for example, a constant speed until the target pressure is reached.

  In addition, pressurize at a high speed (first speed) until just before the target pressure, stop pressurizing for a few seconds, and confirm that the pressure of the air system becomes a steady state (stable state) It is also preferable to perform compression at a low speed (second speed) until the target pressure is gradually reached. Alternatively, it is also desirable to perform compression at a high speed just before reaching the target pressure, and gradually reduce the compression speed to reach the target pressure while bringing the pressure of the air system close to a steady state. That is, the first speed and the second speed described above are not limited to the case where each is a constant speed, and the first speed as the average value and the second speed as the average value are set to high speed and low speed. You may do it.

  After confirming that the pressure of the air system has reached the target pressure, the microprocessor 49 calculates the amount of movement between the arrival point of the piston 27 and a specific start point (origin), and stores it in the storage unit (ROM) 51. . The amount of movement of the piston 27 at this time can be replaced with the total rotation angle of the motor 37. In addition, if the value of the cross-sectional area of the piston 27 to be used is entered in the program in advance, the flow rate of the air sent to the sample chamber 11 from the movement amount of the piston 27 can be calculated by the microprocessor 49. That is, since a calibration sample having a known volume is contained in the sample chamber 11, the movement amount of the piston 27 is compressed to a specific target pressure with the initial pressure being constant as in the measurement principle. It becomes the volume change amount. The actual volume value to be obtained can be determined in advance from the volume of the calibration sample. This calibration process is performed for each of a plurality of calibration volumes having different volumes. These results are substituted into the calculation formula and stored in the storage unit (ROM) 51. That is, a calculation formula used in actual measurement is generated using information obtained from the calibration process.

  Thereafter, the piston 27 moves to the start point (origin) and stops, opens the solenoid valve 41 to release the air system to the atmosphere, and simultaneously displays a display notifying the end of calibration on the display unit 5. If the target pressure is not reached even if the piston 27 moves to the maximum permissible value Rmax as a specific end point during the calibration process, there is a problem such as clogging somewhere in the air system, or the pressure There may be a failure in the sensor 31, the origin sensor 39, the motor 37, the piston 27, the gear 33, the gear 35, and the control device 21. In that case, an error message is displayed on the display unit 5 and the movement of the piston 27 is stopped. At this time, it is preferable to return the piston 27 to the origin or open the electromagnetic valve 41.

  When the calibration work is completed and the actual volume of an unknown measurement sample is measured, the sample to be measured is placed in the sample chamber 11 and sealed, and the start of measurement is input on the operation panel 3 while viewing the display unit 5. The measurement is automatically performed by the control device 21 and the measurement result is displayed on the display unit 5.

  This automatic measurement will be specifically described. First, using the electric signal of the origin sensor 39, the gear 33 attached to the piston 27 is moved to a specific start point (origin) and stopped. This origin processing is performed by rotating the gear 35 by the motor 37. Next, the electromagnetic valve 41 is opened so that the pressure of the air 25 in the air cylinder 23 becomes atmospheric pressure, and actually measured by the pressure sensor 31 and confirmed. That is, the pressure sensor 31 measures the pressure of one air system including the air cylinder 23, the electromagnetic valve 41, the piping 43, the joint 45, and the air outlet 29, and the electric signal is transmitted via the wiring 47 to the control device 21. , And sent to the microprocessor 49 for arithmetic processing to confirm that there is no pressure difference between the air 25 and the atmosphere. If there is a certain pressure difference between the pressure of the air 25 and the atmospheric pressure at this time, there is a problem such as clogging somewhere in the air system, or the pressure sensor 31, the origin sensor 39, the motor 37, the piston. 27, the gear 33, the gear 35, and the control device 21 may have failed. Therefore, an error message is displayed on the display unit 5. As a result, it is possible to prevent actual measurement from being started while a trouble has occurred in the apparatus 1.

  After it is confirmed that there is no pressure difference between the air 25 and the atmosphere, the solenoid valve 41 is closed and the air in the air system is compressed until the target pressure is reached. This compression is performed by driving the motor 37 until the target pressure is reached while calculating and monitoring the electric signal from the pressure sensor 31 by the microprocessor 49. At this time, the piston 27 and the gear 33 move in a direction to send the air 25 in the air cylinder 23 to the sample chamber 11. Since the air system is sealed, the air in the air system is compressed by the piston 27 and the pressure rises.

  The speed at which the air system is compressed (moving speed of the piston 27) is controlled at a constant speed here, but for example, pressurization is performed at a high speed (first speed) until it reaches the target pressure, and is applied for several seconds. After confirming that the pressure of the air system is in a steady state after stopping the pressure, it is preferable to pressurize at a low speed (first speed) until the target pressure is gradually reached. It is also possible to perform compression at a high speed just before reaching the target pressure and gradually reduce the compression speed to reach the target pressure while bringing the pressure of the air system close to a steady state.

  When it is confirmed that the target pressure has been reached, the piston 27 is stopped, and the movement amount that is the difference between the arrival point of the piston 27 and the origin is calculated by the microprocessor 49 and stored in the storage unit (ROM) 51. The amount of movement of the piston 27 at this time can be replaced with the total rotation angle of the motor 37. The microprocessor 49 calculates the actual volume value of the sample from the volume change amount at the time of compression to a specific target pressure, using the calculation formula obtained by the calibration process, and stores it in the storage unit (ROM) 51. . The piston 27 stops after moving to the origin, opens the solenoid valve 41 to open the air system to the atmosphere, and simultaneously displays a display notifying the end of measurement on the display unit 5. At this time, it is desirable to display the actual volume value obtained by the calculation on the display unit 5.

  If the target pressure is not reached even if the piston 27 moves to the maximum allowable value Rmax, there is a problem such as clogging somewhere in the air system, or the pressure sensor 31, the origin sensor 39, the motor 37, the piston 27. There is a possibility that the gear 33, the gear 35, and the control device 21 are faulty. In that case, an error message is displayed on the display unit 5, and the pressurization by the piston 27 is forcibly terminated. This avoids damage to the digital soil physical property measuring apparatus 1.

  In addition, this digital soil physical property measuring apparatus 1 can automatically measure repeatedly a plurality of times, calculate an average value by the microprocessor 49, and store it in the storage unit (ROM) 51. Furthermore, when measuring a plurality of times, if the value compared with the previous measurement value is within a certain range, the measurement can be automatically performed by the microprocessor 49 without repeating the further measurement, and the measurement can be terminated. Further, the measured values measured can be stored as digital data in the storage unit (ROM) 51, and the measured data can be output to the external computer 61 via the output cable 62 and the output connector 15.

  The control device 21 of the digital soil physical property measuring apparatus 1 includes a real time clock 53 as a clock function. The real time clock 53 can input the current time and date on the operation panel 3 while viewing the display unit 5. With this clock function, the date and time of measurement can be added to the measurement data and stored in the storage unit (ROM) 51, whereby data can be easily organized.

  In the embodiment described here, the actual volume is calculated from the amount of change in the air flow rate (compression volume) with respect to a specific target pressure (compression pressure), but the Boyle-Charles law is used. Therefore, a measurement method for obtaining the actual volume from the amount of change in pressure in the sample chamber, which is obtained when a specific target volume is compressed, that is, when the compression volume is made constant, can also be adopted. Since all of them are completely equivalent in principle, the relationship between the target pressure and the air capacity (compression volume) may be replaced with the relationship between the target volume and the pressure change amount, and thus detailed description thereof is omitted.

  The digital soil physical property measuring apparatus 1 can automatically control a series of measurement operations to pressurize until reaching the target pressure in both calibration and measurement, so that measurement errors due to individual differences can be prevented and measurement accuracy can be prevented. Will improve. In particular, in the control device, for example, it is possible to automatically calculate the sample volume using a calculation formula using the Boyle-Charles law, so that measurement errors including calculation errors can be suppressed. Measurement time can be greatly shortened.

  In particular, in the digital soil physical property measuring apparatus 1, calibration is performed using a calibration sample by an automatic calibration means, and the calculation formula of the actual volume is automatically corrected using the result. Measurement with extremely high accuracy. In particular, since the calibration work and the actual measurement work are automatically linked, the burden on the operator can be greatly reduced. Even during the calibration work, a plurality of calibrations are performed using a plurality of calibration samples, so that the calibration system can be enhanced.

  Further, in this automatic calibration means, it is determined whether or not the error during the calibration operation exceeds the allowable upper limit value or the allowable lower limit value. If this upper limit or lower limit is exceeded, an error is displayed because there is a possibility that some abnormality has occurred in the apparatus 1. As a result, a calibration error can be prevented in advance, and an error in starting actual measurement can be reduced while the apparatus 1 is abnormal.

  Furthermore, in the digital soil physical property measuring apparatus 1, an error is displayed on the display unit 5 when the internal pressure of the sample chamber 11 does not reach the target pressure even when pressurized to a specific end point. It is possible to prevent damage to the apparatus 1 and measurement errors.

  Moreover, in this digital soil physical property measuring apparatus 1, at the time of calibration or actual measurement, the piston is moved to a specific starting point and stopped to release the interior to the atmosphere, and a pressure difference of a certain level or more is maintained between the internal pressure and the atmospheric pressure. Whether there is a pressure difference or not is displayed on the display unit. Therefore, it is possible to automatically detect troubles that cannot be recognized by human senses, such as minute clogging and abnormality of each part, before measurement. As a result, measurement errors can be reduced.

  Moreover, in this digital soil physical property measuring apparatus 1, since it is possible to automatically control the pressurization speed to reach the target pressure, the automatic control of the pressurization speed leads to improvement of measurement accuracy and reduction of measurement time. .

  Furthermore, since it is determined whether or not to proceed to the next pressurization based on the amount of pressure change, it is possible to automatically detect an abnormality in the measuring device or the measuring means, and stop the measurement or cause an abnormality to the measurer. It can be notified and the measurement accuracy improves.

  In addition, since it is possible to automatically calculate a repeated average value a plurality of times, there is an advantage of shortening the time required for measurement value calculation. In addition, when measuring the same sample multiple times, if the value compared with the previous measurement value is within a certain range, the measurement can be automatically judged and terminated without repeating further measurement, so measurement time can be maintained while maintaining measurement accuracy. There is merit to shorten.

  Further, since the measured values can be stored as digital data, there are advantages that data input work is reduced and data analysis can be easily performed.

  In the above-described embodiment, the case where the sample chamber 11 is used as the calibration space by setting the calibration sample in the sample chamber 11 has been shown. For example, as shown in FIG. In addition, it is also preferable to prepare a plurality of calibration chambers 11A, 11B, and 11C having different sizes and perform the calibration work. At this time, the calibration chambers 11A, 11B, and 11C including the sample chamber 11 are provided with switching valves 12, 12A, 12B, and 12C for switching the introduction of air into each space. At the time of calibration, any one of these switching valves 12, 12A, 12B, and 12C is turned on and the rest are turned off, so that the sample chamber 11 and the calibration chambers 11A, 11B, and 11C have a total of four calibration spaces. Function. Therefore, calibration can be performed by sequentially introducing air into these calibration spaces. In this way, since a plurality of calibration spaces are prepared in advance, the calibration work can be performed completely automatically from the beginning to the end.

  Further, for example, as shown in FIG. 8, it is also preferable to prepare a variable calibration chamber 16 whose internal volume can be varied by a piston separately from the sample chamber 11 and perform the calibration work. At this time, the sample chamber 11 and the variable calibration chamber 16 are provided with switching valves 12 and 12A for switching the introduction of air into each space. At the time of calibration, the switching valve 12 is turned off and 12A is turned on, and the internal space of the variable calibration chamber 16 is automatically changed in multiple stages to function as a plurality of calibration spaces having different sizes. Therefore, calibration can be performed by sequentially introducing air into these calibration spaces while changing the internal space of the variable calibration chamber 16. In this way, since a plurality of calibration spaces are automatically formed, the calibration work can be performed completely automatically from the beginning to the end.

  In addition, the digital soil physical property measuring apparatus of this invention is not limited to above-described embodiment, Of course, various changes can be added within the range which does not deviate from the summary of this invention.

  The digital soil physical property measuring apparatus of the present invention can be used in various scenes for measuring the actual volume of soil.

1. 2. Digital soil physical property measuring device Operation panel 5. Display unit 7. Housing 9. Power switch 11. Sample chamber 11A. 11B. 11C Calibration room 12.12A. 12B. 12C switching valve 13. Power socket 15. Output connector 16. Variable calibration room 17. Input connector 21. Control device 23. Air cylinder 25. Air 27. Piston 29. Air outlet 31. Pressure sensor 33. Gear 35. Gear 37 Motor 39. Origin sensor 41. Solenoid valve 43. Piping 45. Joint 47. Wiring 49. Microprocessor (CPU)
51. Storage unit 53. Real-time clock 55. Adapter 57. Power cable 59. Storage battery 61. External computer 62. Output cable 63. Host computer 64. Input cable 65. Pressurizing means 67. Pressure measuring means 69. Flow rate measuring means 71. Pressurizing means driving device 101. Pressure control means 103. Pressurization stop means 105. Transition judging means 107. Mean value calculating means 109. Repeat means 111. Output means 113. Measurement value storage means 117. Error notification means 119. Actual volume calculation means 121. Forced termination means 123. Origin processing means 130. Measurement control program

Claims (5)

A sample chamber for measurement,
A pressurizing means for pressurizing the sample chamber;
Pressure measuring means for measuring the pressure in the sample chamber;
A pressurizing means driving device for driving the pressurizing means;
A control device for controlling the pressurizing means driving device;
A display unit for presenting information to the user,
The controller is
Based on the air flow rate required for the sample chamber to reach the target pressure, or based on the pressure change amount obtained when the target flow rate is fed into the sample chamber, the sample volume in the sample chamber is calculated. Volume calculation means ;
When a calibration space having a known volume different from the sample volume is pressurized by the pressurizing means, and the air flow rate until the calibration space reaches the target pressure or when the target flow rate is sent into the calibration space Automatic calibration means for calculating the amount of pressure change obtained in
The actual volume calculation means calculates the sample volume using the air flow rate or the pressure change amount calculated by the automatic calibration means,
The pressurizing means is
A cylinder,
A piston that moves in the cylinder,
The automatic calibration means is
A sample chamber side pipe for communicating the cylinder and the sample chamber;
A sample chamber side valve for opening and closing the sample chamber side piping;
A calibration chamber forming the calibration space;
A calibration chamber side pipe for communicating the cylinder and the calibration chamber;
A calibration chamber side valve for opening and closing the calibration chamber side piping;
A valve operating unit for opening and closing the sample chamber side valve and the calibration chamber side piping,
The valve operating part is
A first state in which only the cylinder and the sample chamber communicate with each other among the cylinder, the sample chamber, and the calibration chamber;
The digital soil physical property measuring apparatus is switched between a second state in which only the cylinder and the calibration chamber communicate with each other among the cylinder, the sample chamber, and the calibration chamber . The calibration room is
A first calibration space communicating with the sample chamber via a first calibration chamber side pipe;
A second calibration space that communicates with the sample chamber via a second calibration chamber side pipe and is different from the volume of the first calibration space;
The automatic calibration means is
A first calibration chamber side valve for opening and closing the first calibration chamber side piping;
A second calibration chamber side valve for opening and closing the second calibration chamber side piping;
The digital soil physical property measuring apparatus according to claim 1, further comprising: a calibration chamber side valve control unit that individually opens and closes the first and second calibration chamber side valves. The calibration space can be switched between a volume V1 and a volume V2 different from the volume V1,
The automatic calibration means calculates the air flow rate or the pressure change amount related to the calibration space in the state of the volume V1, and calculates the air flow rate or the pressure change amount related to the calibration space in the state of the volume V2. The digital soil physical property measuring apparatus according to claim 1, wherein the digital soil physical property measuring apparatus is calculated. The controller is
A state in which the moving speed of the piston in the cylinder is a speed V1,
The digital soil according to any one of claims 1 to 3, characterized in that it can be switched between a state in which the moving speed of the piston in the cylinder is a speed V2 smaller than the speed V1. Physical measurement device. The controller is
When the pressure in the sample chamber is smaller than a threshold value, the moving speed of the piston in the cylinder is set as a speed V1,
5. The digital soil physical property measuring apparatus according to claim 4, wherein when the pressure in the sample chamber is equal to or higher than a threshold value, the moving speed of the piston in the cylinder is set to a speed V <b> 2.