JPH0984857A - Steam sterilizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable sterilization of all objects to be sterilized accurately by starting counting of sterilization time with a counting section when a pressure change pattern shows a stable pressure value for a fixed time after the temperature of sterilization is reached by changes in temperature. SOLUTION: A carrier base for placing an object to be sterilized is provided on the inner bottom part of a chamber and a thermal heater 4 is provided to heat water stored in the chamber. Moreover, the chamber is provided with a temperature detecting section 11 to detect temperature in the chamber and a pressure detecting section 12 to detect a pressure therein. Then, an output of the temperature detecting section 11 is introduced to a temperature gradient calculating section 14 to calculate changes in temperature and an output of the pressure detecting section 12 is introduced to a pressure gradient calculating section 15. Outputs of the temperature gradient calculating section 14 and the pressure gradient calculating section 15 are introduced to a control section 17 to control the operation of a steam sterilizer totally. The control section 17 works to start the counting of sterilization time with a counting section 18 when a pressure change pattern shows a stable pressure value for a fixed time after the temperature of sterilization is reached by changes in temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to steam sterilization for sterilizing an object to be sterilized such as a medical instrument housed in a chamber by converting injected water into high temperature, high pressure steam by heating with a heater. It is related to vessels.

[0002]

2. Description of the Related Art In a steam sterilizer, a predetermined amount of water is poured into a chamber, and the water is heated and boiled by a heater provided in the chamber, so that a high temperature is maintained in the chamber.
It is used to sterilize and disinfect objects to be sterilized such as medical instruments by filling it with high-pressure steam.

In such a high-pressure steam sterilizer,
For example, as disclosed in Japanese Patent Publication No. 4-31707, water is boiled in a state where an exhaust valve of a chamber is opened to remove air, and then the exhaust valve is closed to shift to a sterilization process. There is.

At this time, the timing of closing the exhaust valve is
When transitioning from the air venting process to the sterilization process, the temperature of the steam discharged from the exhaust valve is detected by a temperature sensor, and when the rate of change of the detected temperature shows a stable temperature value for a set period of time, the exhaust valve is turned on. It is supposed to close.

By the way, in order to perform complete sterilization in the sterilization process, it is necessary to exhaust all the air in the chamber, and if there is a region where air remains, reliable sterilization cannot be expected. Therefore, in the above-described conventional steam sterilizer, a temperature sensor detects the temperature inside the chamber during the air venting process, and when the temperature gradient (rate of change) reaches a constant value, the exhaust valve is closed. .

[0006]

The object to be sterilized to be stored in the steam sterilizer is rarely stored as a single item, and in many cases dozens of medical instruments such as scalpels and scissors are collectively stored. Therefore, when the sterilization process is completed after the air bleeding process is completed, even if the temperature near the temperature sensor in the chamber has reached a certain value (boiling point temperature of water under atmospheric pressure), they are stored in a stacked state. The temperature of the central portion of many objects to be sterilized does not always reach a constant value. That is,
Air may remain in the central part of many objects to be sterilized.

However, in the above-mentioned conventional sterilizer described above, even if the temperature of the central portion of a large number of objects to be sterilized has not reached a constant value (that is, if air remains), a temperature sensor is used. If the temperature in the vicinity reaches a certain value, the air bleeding process is terminated and the sterilization process is started.

In other words, since the sterilization process is performed while air remains in the chamber, the sterilization process ends at the central portion of many objects to be sterilized without reaching the sterilization temperature. Therefore, there is a problem that the object to be sterilized is not completely sterilized, resulting in poor sterilization.

The present invention was devised to solve the above problems, and an object thereof is steam sterilization capable of reliably sterilizing all sterilized objects regardless of the quantity of the sterilized objects stored in the chamber. To provide a container.

[0010]

In order to solve the above problems, the steam sterilizer of the present invention stores a chamber for accommodating an object to be sterilized and having a heater on the inner bottom, and water to be injected into the chamber. A water storage tank, a water supply pipe communicating the water storage tank with the chamber, a water supply / drainage valve for opening / closing the water supply pipe, an exhaust pipe for discharging steam generated in the chamber, and an opening / closing of the exhaust pipe. In a steam sterilizer equipped with an exhaust valve, a temperature detection unit that detects the temperature inside the chamber, a pressure detection unit that detects the pressure inside the chamber, and a sterilization time of the sterilized object stored in the chamber A counting unit that counts, a temperature measurement unit that measures a temperature change based on the temperature detected by the temperature detection unit, a pressure measurement unit that measures a pressure change based on the pressure detected by the pressure detection unit, and the temperature Control for starting counting of sterilization time by the counting unit when the pressure change pattern measured by the pressure measuring unit shows a stable pressure value for a certain period of time after the temperature change measured by the measuring unit reaches the sterilization temperature. And a section.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a schematic diagram of the steam sterilizer of the present invention.

In FIG. 1, a steam sterilizer is mainly composed of a chamber 1 for storing an object to be sterilized (not shown), which is a medical instrument such as tweezers and an injection needle, and a water storage for storing water to be injected into the chamber 1. Tank 8 and this water storage tank 8
And a chamber 1, and a water supply pipe 6 that communicates with the chamber 1, a water supply / drainage valve 7 that opens and closes the water supply pipe 6, an exhaust pipe 9 that discharges steam generated in the chamber 1, and an exhaust valve that opens and closes the exhaust pipe 9. 10 and 10.

An opening / closing lid 2 is mounted on one side of the chamber 1. Further, a mounting table 5 for mounting an object to be sterilized is provided on the inner bottom portion of the chamber 1, and a heater 4 for heating water stored in the chamber 1 is also provided. Further, the chamber 1 is provided with a temperature detection unit 11 that detects the temperature inside the chamber 1 and a pressure detection unit 12 that detects the pressure inside the chamber 1.

As the water supply / drain valve 7 and the exhaust valve 10, for example, an electromagnetic valve or a ball valve is preferably used.

FIG. 1 is a block diagram showing an electric configuration of the steam sterilizer having the above configuration.

That is, the output of the temperature detecting unit 11 is led to the temperature gradient calculating unit 14 which calculates the temperature change (temperature gradient in this example) based on the detected temperature, and the output of the pressure detecting unit 12 is It is guided to a pressure gradient calculation unit 15 which calculates a pressure change (a pressure gradient in this example) based on the detected pressure.

The outputs of the temperature gradient calculation unit 14 and the pressure gradient calculation unit 15 are led to a control unit 17 which controls the overall operation of the steam sterilizer.

Each control output of the control unit 17 includes a heater drive unit 19 for driving the heater 4, a water supply / drain valve drive unit 20 for opening / closing the water supply / drain valve 7, and an exhaust valve drive for opening / closing the exhaust valve 10. It is guided to the part 21. In addition, the control unit 17 controls the sterilization time in the sterilization process and the pressure gradient calculation unit 1
It is bidirectionally connected to the counting unit 18 which counts a fixed time after the pressure change calculated in 5 becomes a constant value (constant gradient).

The normal operation of the steam sterilizer will now be described with reference to the flow chart shown in FIG. 3 and the temperature and pressure change chart shown in FIG.

When the steam sterilizer starts its operation, the control unit 1
7 controls the water supply / drainage valve drive unit 20 to open the water supply / drainage valve 7. As a result, the water in the water storage tank 8 passes through the water supply pipe 6 due to the height difference and is poured into the chamber 1 (step S1). At this time, the exhaust valve 10 is in an open state. Then, when the water injection is completed, the control unit 17
The water supply / drainage valve drive unit 20 is controlled to close the water supply / drainage valve 7.

After that, the controller 17 controls the heater driver 19 at time t1 to start energizing the heater 4 (step S2). As a result, the water in the chamber 1 is heated and the water temperature rises (indicated by reference numeral 31).
At this time, since the exhaust valve 10 is in the open state,
The pressure in the chamber 1 is constant at atmospheric pressure (approximately 1 atm) (indicated by reference numeral 41).

When the temperature reaches the boiling point temperature of water (100 ° C.) at time t2 (step S3), the internal temperature stabilizes near the boiling point temperature (indicated by reference numeral 32).
After confirming that the internal temperature is stable near the boiling point temperature, the control unit 17 closes the exhaust valve 10 at time t3.

When the exhaust valve 10 is closed, the chamber 1 is hermetically closed, and thereafter, the internal pressure of saturated chamber rises (indicated by reference numeral 42) and the internal temperature of the chamber 1 also rises as the pressure rises (see FIG. 42). Reference numeral 33). Then, the internal temperature of the chamber 1 becomes
When the temperature is increased to the sterilization temperature of 130 ° C. in 4, the controller 17 controls the heater 4 so that the temperature becomes constant (steps S4 and S5). for that reason,
After time t4, the sterilization temperature is stabilized at 130 degrees, and the internal pressure is also kept constant at the value at time t4 (indicated by reference numerals 34 and 43).

At this time, the control unit 17 starts the counting of the constant time T0 from the time t4 when the internal pressure becomes constant by the counting unit 18, and when the constant state of the internal pressure is counted for the time T0, counts at the time t5. The count value of the unit 18 is cleared (steps S6, S7, S8), and at the same time, the time T4 which is the sterilization time is counted by the counting unit 18 (step S
9). That is, the sterilization process is started at time t5.

At time t8 when time T4, which is the sterilization process, has elapsed, heating by the heater 4 is stopped (steps S10 and S11), and the exhaust valve 1
0 is released (step S12). As a result, the time t
From 8 onward, the temperature and pressure inside the chamber 1 drop sharply,
Eventually, the temperature will drop to atmospheric temperature and atmospheric pressure, and then stabilize.

That is, in normal operation of the steam sterilizer,
As shown in FIG. 4, at time T1, which is the heating time of water, the internal temperature rises at a constant gradient, the internal pressure is kept at atmospheric pressure (reference numerals 31 and 41), and after reaching the vicinity of the boiling point temperature, the exhaust gas is exhausted. The time T2 until the valve 10 is closed is kept constant with the internal temperature and the internal pressure (reference numerals 32 and 41), and the time T3 when the internal temperature rises to the sterilization temperature after the exhaust valve 10 is closed is the internal temperature and the internal pressure. Both the internal pressure rises at a constant gradient (symbols 33, 42), and after reaching the sterilization temperature, the exhaust valve 10
The time T4 until the opening is maintained at both the internal temperature and the internal pressure (reference numerals 34 and 43).

Here, the pressure change when a large number of objects to be sterilized are accommodated in the chamber 1 and an air layer is formed in the central portion of the objects to be sterilized due to this is shown by the alternate long and short dash line in FIG. Show.

In this case, time T1 which is the heating time of water
The internal pressure is maintained at atmospheric pressure as in the case of normal operation (reference numerals 31 and 41). Also, during the time T2 after reaching the vicinity of the boiling point temperature until the exhaust valve 10 is closed, the internal pressure is kept constant (reference numerals 32 and 41) as in the case of normal operation.

However, after the exhaust valve 10 is closed, at time T3 when the internal temperature rises to the sterilization temperature, the internal pressure rises at a constant gradient as in the case of normal operation, but the rate of increase is usually It is smaller than that of the operation (reference numeral 422). This is because at time t4 when it is determined that the internal temperature has reached the sterilization temperature, air actually remains in the central portion of many sterilized objects.

Therefore, after reaching the sterilization temperature, the exhaust valve 10
During the time T4 until opening, the internal pressure rises at a constant gradient due to the influence of this residual air (reference numeral 4).
33). This is because the air at a temperature lower than the sterilization temperature remains in the central portion of many objects to be sterilized, and the remaining air is gradually warmed and expanded, so that the pressure in the closed chamber 1 rises. Is.

As a result of storing a large number of objects to be sterilized in the chamber 1 as described above, when the exhaust valve 10 is closed by reaching the boiling temperature in the chamber 1, the central portion of the objects to be sterilized is increased. When there is residual air in, the pressure shows a characteristic change compared to when there is no residual air.

Therefore, in the steam sterilizer of the present invention, the sterilization process is focused on the difference in pressure change pattern between the operation when there is no residual air when closing the exhaust valve 10 and the operation when there is residual air. It is possible to surely start counting.

The operation when there is residual air in the chamber 1 when the exhaust valve 10 is closed will be described below from time t4.

As described above, when air remains in the central portion of a large number of objects to be sterilized stored in the chamber 1 when the exhaust valve 10 is closed (time t3), the subsequent pressure change is The pattern shown by the alternate long and short dash line in FIG. 4 is obtained.

That is, when the internal temperature of the chamber 1 rises to the sterilization temperature of, for example, 130 degrees at time t4, the controller 17 controls the heater 4 so that it becomes a constant temperature thereafter (steps S4 and S5). . Therefore, the temperature change calculated by the temperature gradient calculation unit 14 is stable at the sterilization temperature of 130 degrees after time t4, but the pressure change calculated by the pressure gradient calculation unit 15 remains constant after time t4. Keep rising.

Therefore, in this case, unlike the normal steaming operation, the sterilization process is not started at time t5. That is, the counting of the sterilization process by the counting unit 18 is not started.

The increase of the internal pressure after time t4 stops around time t6 and then becomes a substantially constant value until time t8.

Therefore, the control unit 17 counts the constant time T0 from the time t6 when the internal pressure becomes almost constant.
8 and counting the constant state of the internal pressure for the time T0, the count value of the counting unit 18 is cleared at the time t7 (steps S6, S7, S8) and at the same time, the count of the time T4 which is the sterilization time is counted. The process is started by the unit 18 (step S9). That is, the sterilization process is started at time t7.

Subsequent operations are the same as in the above-mentioned normal operation.

[0041]

The steam sterilizer of the present invention counts the sterilization time of the temperature detection part for detecting the temperature in the chamber, the pressure detection part for detecting the pressure in the chamber, and the sterilization object to be sterilized stored in the chamber. Counter, a temperature measuring unit that measures a temperature change based on the temperature detected by the temperature detecting unit, a pressure measuring unit that measures a pressure change based on the pressure detected by the pressure detecting unit, and a temperature measuring unit. After the temperature change reaches the sterilization temperature, when the pressure change pattern measured by the pressure measurement unit shows a stable pressure value for a certain period of time, the control unit starts counting the sterilization time by the counting unit. Therefore, it is possible to surely sterilize all the sterilized objects regardless of the amount of the sterilized objects stored in the chamber.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electric configuration of a steam sterilizer of the present invention.

FIG. 2 is a schematic configuration diagram of a steam sterilizer of the present invention.

FIG. 3 is a flow chart for explaining the operation of the steam sterilizer of the present invention.

FIG. 4 is a graph showing changes in temperature and pressure during operation of the steam sterilizer of the present invention when the exhaust valve is closed and when there is no residual air.

[Explanation of symbols]

 1 Chamber 4 Heating Heater 6 Water Supply / Drainage Pipe 7 Water Supply / Drainage Valve 9 Exhaust Pipe 10 Exhaust Valve 11 Temperature Detection Section 12 Pressure Detection Section 14 Temperature Gradient Calculation Section (Temperature Measurement Section) 15 Pressure Gradient Calculation Section (Pressure Measurement Section) 17 Control Section 18 Counting Department

Claims (1)

[Claims] 1. A chamber for accommodating an object to be sterilized and having a heater at an inner bottom thereof, a water storage tank for storing water to be injected into the chamber, a water supply pipe connecting the water storage tank with the chamber, In a steam sterilizer equipped with a water supply / drain valve for opening / closing a water supply pipe, an exhaust pipe for discharging steam generated in the chamber, and an exhaust valve for opening / closing the exhaust pipe, the temperature in the chamber is detected. A temperature detection unit, a pressure detection unit that detects the pressure in the chamber, a counting unit that counts the sterilization time of the sterilized object stored in the chamber, and a temperature change based on the temperature detected by the temperature detection unit. A temperature measurement unit for measuring, a pressure measurement unit for measuring a pressure change based on the pressure detected by the pressure detection unit, and a temperature change measured by the temperature measurement unit after reaching the sterilization temperature, A steam sterilizer comprising: a control unit for starting counting of the sterilization time by the counting unit when the pressure change pattern measured by the pressure measuring unit shows a stable pressure value for a certain period of time.