JPH0676947B2 - Package leak measuring device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a package leak measuring device used for inspecting the presence or absence and the degree of leakage of a package in which foods, pharmaceuticals, etc. are hermetically sealed.

[Prior Art] A conventional leak measuring device of this type of package measures the fluctuation value of the chamber internal pressure by connecting the chamber containing the package to be tested to a vacuum pump and reducing the chamber internal pressure by the vacuum pump. The quality of the airtightness of the package is determined.

In detail, the suction of the air in the chamber includes the following two methods. One of them is low-speed suction of the air in the chamber in order to reduce the pulsation of the valve internal pressure caused by the elasticity of the air when the valve provided in the suction pipe that connects the chamber and the vacuum pump is closed. (The amount of suction per unit time is reduced), and the other one is to suck the air in the chamber at high speed in order to shorten the time until the chamber internal pressure reaches the set pressure. Is.

Further, to describe the chamber internal pressure measurement in detail, almost all of the pressure detectors were provided in the pipe branched from the intake pipe.

Further, when the valve control is described in detail, the control is performed on the basis of a preset time.

However, in the above-mentioned conventional leak measuring apparatus, when the air suction in the chamber is performed at a low speed, there is a problem that it takes a long time for the chamber internal pressure to reach the set value, and therefore a large amount of continuous inspection is required. It was inefficient at doing.

Also, in the case where the air in the chamber is sucked at high speed, the valve is closed within a predetermined time while rapidly sucking,
The pulsation of the chamber internal pressure increases with the closing, and there is a problem that the chamber internal pressure after the valve is closed changes repeatedly due to the relationship between the large pulsation and the valve operating characteristics.

Further, since the closing operation of the valve is performed on the basis of a preset time, there is a problem that the actual pressure in the chamber becomes a value that is influenced by the error in the air suction speed and the variation in the valve operation.

Furthermore, a pressure detector for measuring the chamber pressure is
Since it is provided in the pipe branched from the intake pipe, there is a problem that a deviation occurs between the actual pressure in the chamber and the measured value due to elasticity of air while the pressure in the chamber is pulsating.

[Problems to be Solved by the Invention] The present invention has been made in consideration of such problems of the conventional package leak measuring device, and its object is to reduce the suction speed of the air in the chamber. The pulsation of the chamber internal pressure when the valve is closed is reduced, and the difference between the actual chamber internal pressure and the detected measurement value is reduced, which enables the package leak test in a short time with high accuracy. It is intended to provide a leak measuring device capable of performing the above.

[Means for Solving the Problems] The present invention has been made based on the above-mentioned problems, and includes a chamber for accommodating a package to be inspected, a vacuum pump,
An intake pipe that communicates the inside of the chamber with the vacuum pump, a valve for opening and closing an air flow path provided in the intake pipe, a control unit that controls opening and closing of the valve, and an internal pressure display unit of the chamber, A leak opening for introducing outside air into the intake pipe is provided between the valve and the vacuum pump, and the amount of outside air introduced by the leak opening increases as the chamber internal pressure approaches a predetermined set pressure. Is provided with a pressure detector at a position that directly receives the pressure inside the chamber, and the control unit is provided with a control circuit for closing the valve based on a comparison value between the output of the detector and the set pressure. By the operation of the vacuum pump, the pressure in the chamber is rapidly reduced toward a predetermined set pressure,
Whether or not there is a leak in the package under test is detected from the time required to reach this set pressure, and when the pressure in the chamber that is decompressed under the leak condition of the intake pipe reaches the predetermined set pressure, the air flow path opening / closing The valve for operation is closed, and the pulsating pressure in the chamber is suppressed by the depressurizing action under this leak state, and the pressure in the chamber is maintained at the judgment reference pressure slightly higher than the set pressure for a predetermined time. The pressure detector detects changes in the pressure in the chamber containing the package to be tested within the predetermined time, and measures the degree of package leakage.

[Operation] When the air in the chamber is sucked at high speed by the vacuum pump, the time until the chamber internal pressure reaches the predetermined set pressure is shortened. As the chamber pressure approaches this set pressure,
The amount of introduction of the outside air into the intake pipe by the leak opening increases, and the intake amount of the vacuum pump hardly changes, but the speed of reducing the chamber internal pressure becomes slow. When the chamber internal pressure reaches a predetermined set pressure and the valve is closed when the pressure reduction rate is slow, the pulsation of the chamber internal pressure that occurs when the valve is closed is far greater than when the valve is closed in the high-speed pressure reduced state. Becomes smaller. Therefore, the internal pressure of the chamber converges to a substantially constant value in a shorter time.

By providing the pressure detector at a position that directly receives the internal pressure of the chamber, the internal pressure of the chamber is directly detected. Therefore, the package leak value display and the valve closing operation are performed based on the measured value of the chamber internal pressure.

[Embodiment] An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a relationship between a change in chamber pressure and time, comparing a conventional device and a device according to the present invention. FIG. 2 is a diagram showing the relationship between changes in chamber internal pressure and measurement time in this example. Third
The drawing is a partial view showing the operation unit and the display unit of the device of the present invention.
FIG. 4 is a conceptual diagram of the configuration of the device of the present invention.

Referring to FIG. 1, (A) shows an example in which the air in the chamber is sucked at high speed by a conventional device. In this example, the pulsation of the chamber pressure after closing the valve in the suction passage is large,
Further, there is a defect that the difference between the predetermined set pressure in the chamber and the actual pressure is widened, and further, the time a until the chamber internal pressure stabilizes becomes long. (B) shows an example in which the air in the chamber is sucked at a low speed by the conventional device. In this example, the time until the chamber internal pressure reaches the set pressure, that is, the interval od becomes long, and the leak inspection is started. The result is that it is troublesome. (C) shows an example in which the air in the chamber is sucked at a relatively high speed by the apparatus of the present invention. According to this example, the difference between the predetermined set pressure of the chamber internal pressure and the actual pressure becomes small, and the suction is started. It is characterized in that the time c from when the chamber pressure stabilizes is short.

Referring to FIG. 2 according to the above feature of the present invention, t ₁ represents the time from the start of air suction in the chamber to the time when the chamber internal pressure reaches a predetermined set pressure P ₁ , and t ₂ represents the chamber internal pressure set. The time from the time when the value reaches the value to the time when the chamber internal pressure reaches the stable internal pressure P ₂ is shown, and t ₃ shows the time zone for measuring the leak state of the package under test. In this case, the length of t _3, the test packages to be measured is intended to be predetermined at the time of measurement by considering the condition of the volume, such as occupied in the chamber, after the time course of the t ₃ also leaks at all If not, the variation in the pressure in the chamber does not occur, this time, the internal pressure P ₂ after a time of t ₃ ', the time t ₃
Since the internal pressure is the same as the chamber internal pressure P _{2 at} the initial stage of, the dotted line connecting P ₂ and P ₂ ′ in the figure is used as the determination reference pressure line. Therefore, the leak measurement of the package under test is started after t ₁ + t ₂ hours when the chamber internal pressure stabilizes. Naturally, the time to reach the set pressure P ₁
to t _1, in a case where a long time than this is not even reach the set value passed, although in the test package seen that a leak state lags behind these predetermined time t ₁ is the test package In the case of a large leak in the chamber, the length of such delay is also dominated by the volume of the package under test occupying in the chamber. Determination of good or bad depends on the degree of leakage of the test package is carried out during which reaches the end of the measurement time t _3, in particular, the end point in a chamber internal pressure of the time zone, in advance as a reference on the quality-size determination of the package If the allowable range p is not exceeded, that is, P ₂ ′
When the chamber internal pressure corresponding to + p is defined as P ₃ , if the chamber internal pressure is within the range between P ₂ ′ and P ₃ , it is judged as a good product, and conversely, if it exceeds the allowable pressure range p, it is a defective product. Is determined. If there is a leak in the package to be inspected, the internal air leaking from the package to be inspected and leaking into the chamber causes the internal pressure in the chamber to increase with time, and the internal pressure increases from P ₂ to P ₃ or higher. reached since a line connecting 'and criteria pressure curve connecting the internal pressure P ₂ of the measurement end time' hatched portion and P _2, P ₂ connecting the drawing pressure P ₂ and P ₃ and the allowable internal pressure P ₃ due to leakage Using the range of the triangle surrounded by (shaded in the figure), the case where the chamber internal pressure shows a pressure value outside this triangular area at any point during the time zone t ₃ is a defective product. To determine. The allowable pressure range p and the measurement time t ₃ are set according to the specifications of the package under test as described above, and the setting is performed by the digital switches 9 and 10 in FIG. Be done. In addition, p'in the figure is the difference between the set pressure and the measured zero level set by the zero reset.

Explaining in detail about zero reset, this is performed in order to remove the fluctuation of the chamber internal pressure caused by the pulsation of the chamber internal pressure within the time t ₂ and the expansion of the package itself from the measurement result. It is effective to prevent the judgment. In this zero reset, the chamber pressure is set to P ₁
It will be automatically performed when 0.1 seconds has passed since the time was reached.

Note that, in FIG. 2, the width of the symbol p is drawn to be larger than the actual size for easy understanding.

Next, description will be given of each part of each device for performing the measurement according to the above-mentioned measuring procedure. Referring to FIG.
Is a pressure display portion, 3a and 3b are pressure scale switching display lamps, 4 is a lamp for displaying the quality judgment result of the package to be tested, and 5 is a power on / off display lamp. The pressure scale can be switched between when the air in the chamber is being sucked by the vacuum pump and when the degree of leak is being measured.The pressure is displayed in mmHg during suction, and the measurement is performed. Time is displayed in mmH ₂ O.
As a result, the scale resolution is higher during measurement than during aspiration. 6 is a measurement condition setting unit.
In addition to the pressure setting dial 7, the setting unit 6 incorporates a digital switch 8 for setting the chamber decompression time, and the operation of the apparatus is performed in the next step only when the chamber pressure reaches the set pressure within the set time. It is designed to proceed to. When the chamber internal pressure does not reach within the set time, it is determined that there is a large leak including the state of the chamber. Reference numeral 9 is a measuring time setting digital switch, and 10 is a judgment reference value setting digital switch. Reference numeral 11 denotes an operation section, which is provided with an automatic measurement button 12, an operation stop button 13, a vacuum pump remote control button 14, and a main power button 15, among which the automatic measurement button 12 Is for enabling automatic measurement simply by pressing this button after setting a predetermined value in the setting unit 6, and the operation stop button 13 causes an abnormality during operation of the device by automatic measurement. It is an operation button that stops the operation at any time, and the vacuum pump remote control button is connected to the vacuum pump power supply,
The main power button 15 is an operation button that enables remote operation, and the main power button 15 is an operation button that turns on and off all electrical systems in the measuring apparatus.

The relationship between each of these operating members and each part of the apparatus will be described with reference to FIG. 4. Reference numeral 21 is a measurement / control unit, and 22 is a pressure detector. The pressure detector 22 is of a semiconductor type, and its detection surface is attached in an airtight state to an upper lid 27 which occupies a position facing the inside of the chamber. 23 is chamber 26
A valve for opening and closing a flow path provided in an intake pipe 28 that communicates with the vacuum pump 25, and a leak opening 24 that is opened and closed by the valve and is always kept open during measurement. The main body of the chamber 26 is provided with a packing for airtightly joining the two in a portion in contact with the upper lid 27.

The measurement / control unit 21 includes a comparator, and the comparator compares the set pressure P ₁ with the output of the pressure detector 22, and the output of the pressure detector 22 reaches the set pressure P ₁ . When this is done, the valve 23 is closed.

In this example, the pressure during suction is mmHg, and the pressure during measurement is
mmH it is assumed that each display at ₂ O, may of course also be displayed in mmH ₂ O all.

Next, the operation of this embodiment will be described. When the vacuum pump 25 operates, the vacuum pump 25 has a capability of sucking at high speed, so that the internal pressure of the chamber 26 reaches the set pressure in a short time. As the chamber internal pressure approaches the set pressure, the amount of outside air introduced into the intake pipe 28 from the leak opening 24 increases, and the air suction speed of the vacuum pump 25 hardly changes, but the depressurization speed in the chamber decreases. . Even if the pressure reduction rate of the chamber internal pressure becomes slow, the internal pressure gradually reaches the set pressure, and at the same time when the set pressure is reached, the valve 23 is closed. In this case, the internal pressure pulsation of the chamber 26 that occurs when the valve is closed is smaller than that when the valve is closed in the high-speed depressurization state.

The pressure detector provided inside the chamber 26 so as to directly receive the internal pressure of the chamber 26 directly detects the pressure inside the chamber. Therefore, unlike the case where the pressure detector is provided in the branch pipe, the measured value does not include the difference between the chamber internal pressure value and the branch pipe internal pressure value caused by the elasticity of air.

[Effects of the Invention] The present invention, which is configured as described above, has the effects described below.

Since the vacuum pump with high-speed suction capability is provided and the leak opening is provided as described above, the time required for the chamber internal pressure to reach the vicinity of the set pressure is shortened, and suction by stopping the valve is stopped. The time from when the chamber pressure stabilizes is shortened. Therefore, the leak measurement start time of the package to be inspected is shortened, and the package inspection efficiency of mass-produced products such as foods and pharmaceuticals can be greatly improved.

In addition, the chamber internal pressure detector is installed so that its detection surface directly receives the chamber internal pressure, and the valve is closed and the leak value is measured by the output of the pressure detector, so the package leak inspection can be performed with high accuracy. Can be done.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a change in chamber internal pressure and time, comparing a conventional device and a device according to the present invention. FIG. 2 is a diagram showing the relationship between changes in chamber internal pressure and measurement time in the example. FIG. 3 is a partial view showing the operating section and the display section of the device of the present invention. FIG. 4 is a conceptual diagram of the configuration of the device of the present invention. 22 …… pressure detector, 23 …… valve, 24 …… leak opening 25 …… vacuum pump, 26 …… chamber, 28 …… intake pipe

Claims (1)

[Claims] 1. A chamber for accommodating a package to be inspected, a vacuum pump, an intake pipe for communicating the inside of the chamber with the vacuum pump, a valve provided in the intake pipe for opening and closing an air flow path, and the valve. A control unit for controlling opening and closing of the chamber, and an internal pressure display unit for the chamber, and a leak opening for introducing outside air into the intake pipe is provided between the valve and the vacuum pump. The outside air introduction amount is configured to increase as the chamber internal pressure approaches a predetermined set pressure, the chamber is provided with a pressure detector at a position that directly receives the pressure inside the chamber, and the control unit includes: A leak measuring device for a package, comprising a control circuit for closing the valve based on a comparison value between an output of a detector and the set pressure.