JPS6410227B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steam sterilizer that sterilizes objects to be sterilized such as syringe needle forceps using saturated steam, and in particular, a single limiter circuit prevents abnormal heating during sterilization and drying, and This enables sterilization even immediately after the drying process.

In this type of product in which a drying process is performed after the sterilization process, the temperature in the drying process is higher than that in the sterilization process. This is because during the sterilization process, the heater is submerged in water, but during the drying process, the heater is in a state similar to dry firing and heats the ambient air, resulting in a reasonably high temperature.

For this reason, a plurality of temperature fuses or thermostats have been used as limiter means to prevent abnormal heating, depending on the respective set temperatures during the sterilization process and the drying process. However, as mentioned above, it requires a plurality of temperature fuses or thermostats, which has the disadvantage of being expensive. In addition, if a single limiter means, for example a thermistor, is used to switch the limiter temperature during the sterilization process and the drying process, in order to perform the sterilization operation again after the completion of the drying process, the thermistor must be turned off immediately after the drying process. Since the resistance value increases during the drying process, drying cannot be performed until the thermistor is naturally cooled and its resistance value decreases, which is extremely inconvenient when used continuously. Ta.

The present invention has been made in view of the above-mentioned drawbacks, and will be explained below based on the drawings. 1 is a box-shaped frame, 2
3 is a horizontally elongated bottomed cylindrical chamber with an open front side and a bottom-shaped rear side; 3 is a water storage tank provided on the side of the chamber; and is connected to the inner bottom of the chamber by a pipe 4. Reference numeral 5 denotes a lid body that can open and close the opening of the chamber 2 from the inside to make it airtight; 6 a sterilization heater whose side surfaces are bent in a square shape and fixed insulated to the inner bottom of the chamber; 7 a periphery of the chamber 2; This is a drying heater for the band wrapped closely around the body, and during the drying process, it cooperates with the sterilization heater 6 to dry the air inside the chamber.

Reference numeral 8 denotes a water level detection rod having a pair of detection electrodes 9, 9' on its upper part, the electrodes being positioned above the sterilization heater 6 and fixed to the inner bottom of the chamber 2; When the water injected from the tank 3 through the pipe 4 reaches a predetermined water level located on the upper surface of the sterilization heater 6, the respective detection electrodes 9 and 9' are electrically connected to the sterilization heater 6. This short circuit activates the water level detection circuit, which will be described later, and water injection is completed. Reference numeral 10 denotes a heat-sensitive element which is provided at the inner bottom of the chamber 2, and whose upper part is positioned approximately at the same position as the predetermined water level, and whose resistance value decreases with temperature. Reference numeral 11 denotes a thermostat provided at the outer bottom of the chamber 2 and set at a relatively higher temperature than the normal temperature for preventing dry firing.

Next, the electric circuit will be explained. VC is the power supply circuit, and TS is the heat-sensitive element 1 for obtaining a comparison voltage.
A temperature detection circuit consisting of a series circuit of 0 and a resistor R1 and two fixed resistors R2 and R3 for obtaining a reference voltage, AP has one input terminal connected to the above-mentioned comparison voltage circuit side, and the other input terminal connected to the above-mentioned comparison voltage circuit side. An amplifier circuit mainly having an amplifier AF connected to the reference voltage circuit side of the circuit and whose output terminal is connected to the other input terminal.
VT is a reference voltage circuit consisting of resistors R4 and R5 and a potential adjustment resistor VR, and TC has one input terminal connected to the connection between the resistor R5 of the reference voltage circuit VT and the potential adjustment resistor VR; A temperature control circuit for a drying heater 7 which mainly has a comparator CP1 whose input terminal is connected to the output terminal of the amplifier AF of the amplifier circuit AP, VS has one input terminal connected to the other of the comparator CP1 of the temperature control circuit TC. A potential comparator circuit which is connected to an input terminal and has the other input terminal connected to the resistor R4 and resistor R5 of the reference voltage circuit VT, which mainly has a comparator CP2, switches the limiter temperature during sterilization and drying according to the respective strokes. It is something. VA is a potential setting device consisting of a transistor TR1 connected in parallel to the potential adjustment resistor VR of the reference voltage circuit VT, and RS is the other input terminal of the temperature control circuit TC and one input terminal of the potential comparison circuit VS. LT is a limiter circuit, which is a normally open reset switch connected between the connection part of VS and the chassis side. is the power source, and the emitter is connected to a drive circuit D consisting of a heater control relay that controls sterilization and drying heaters 6 and 7, which will be described later.
It consists of 3.

The drive circuit will be described. T is a timer motor TM, a first timer switch TS1 for executing the sterilization and drying process that is turned on for a certain period of time by the motor, and a second timer switch for notification that is turned on for about 30 seconds before the first timer switch is turned off.
TS2, the first timer switch TS1 is connected to the cutoff transistor TR3.
is connected to the emitter. X1 is the cutoff transistor TR3 and the first timer switch TS.
The first relay is connected between the connection part of No. 1 and the chassis, and has a normally open type relay contact X1s. RY1
is a drying heater control relay whose base is connected to the drive transistor TR4 whose base is connected to the output terminal of the temperature control circuit TC, and has a normally open relay contact.
It has RS1. X2 is the drying heater control relay RY1 and drive transistor TR4
A second relay is connected in parallel to the series circuit, and has a relay contact X2s, a movable contact X2a, and a fixed contact X2b connected to the drying heater control relay RY1.
and a normally closed fixed contact X2c of the movable contact X2a. ST1 is the first timer switch TS
ST2 is a drying start switch connected between the connecting part of timer switch TS1 and second timer switch TS2 and the drying heater control relay RY1, and ST2 is a sterilization start switch connected in series to the normally closed fixed contact X2c of the second relay X2. , X3 is a third relay connected in series to the switch, which includes a self-holding relay contact X3s connected in parallel to the sterilization start switch ST2, a movable contact X3a, and two fixed contacts X3.
b, X3c. OS is an oscillation circuit consisting of a multivibrator connected to the second timer switch TS2, and its output transistor
A buzzer relay BX is connected to TR5, and the alarm is intermittent for about 30 seconds when the second timer switch TS2 is turned on before the end of sterilization. X4 is a fourth relay having one end connected to a relay contact of a fifth relay described later and the other end connected to a drive transistor TR6, and has a relay contact X4s, a movable contact X4a, and two fixed contacts X4b and X4c. The contact X4a is connected to the sterilization start switch ST2, one fixed contact X4c for normally closed of the movable contact X4a is connected to the water level detection circuit side, and the other fixed contact X4b is connected to the sixth relay for driving the timer motor TM and Connected to the pressure switch side. WS is a water level detection circuit having one end connected to the fixed contact X4c and having water level detection electrodes 9, 9' on one side; X5 is a water level detection circuit having one end connected to the fixed contact X4c of the fourth relay X4 and the other end Output transistor of circuit Ws
The fifth relay connected to TR7, movable contact X5a
and two fixed contacts X5b and X5c, and when a predetermined water level is detected, the other normally closed relay contact X5s is opened to deenergize the fourth relay X4. PS1 is a first pressure switch that has a movable contact PSa and two fixed contacts PSb and PSc.
to the other fixed contact PSb.
RY2 is a sterilization heater control relay connected to one fixed contact PSc of the first pressure switch PS1, and a movable contact PSa of the first pressure switch PS1.
The sterilization heater 6 is turned off by the operation. X
6 is a sixth relay for driving the timer motor TM which is connected in series to the drying start switch ST1, and has two relay contacts X61 and X62. It is connected between fixed contacts X4b of relay X4. TR8 is a transistor for generating continuous sound of the buzzer, which is connected in parallel to the output transistor TR5 of the oscillation circuit OS, and whose base is connected to the drying start switch ST1.

M is a main circuit that operates each electrical component based on the operation of the relay contacts driven by the respective relays of the drive circuit D described above. The specific circuit will be explained. AC is an alternating current power supply, and sterilization heater 6 is the relay contact RS2 of the sterilization heater control relay RY2.
It is connected in series with the AC power source AC via the thermostat 11. PL1 is a sterilization indicator lamp, which is connected to the relay contact X1s of the first relay X1 and the relay contact X4s of the fourth relay X4, and is connected in parallel to the sterilization heater 6. The drying heater 7 is connected in series to the relay contact PS1 of the drying heater control relay RY1, and this series circuit is connected in parallel to the relay contact RS2 of the sterilization heater 6. PL2 is a power indicator lamp connected to the relay contact X1s of the first relay X1 via the thermostat 11, BZ is a buzzer connected in series to the relay contact BXS of the buzzer relay BX, and PL3 is a relay contact of the second relay X2. A drying indicator lamp is connected in series to Dryness indicator lamp PL3 and relay contact X2s of second relay X2
and the solenoid valve BV, and after sterilization is completed, the solenoid valve BV is driven to exhaust the pressure inside the chamber 2. PL4 is the third
A water injection indicator lamp is connected in series to fixed contact X3b of relay X3, and this series circuit is connected to the electromagnetic valve.
Connected in parallel to BV. PS2 is a second pressure switch fixed to the chamber 2, which closes at a predetermined pressure lower than that of the first pressure switch PS1. It is connected to the closed side fixed contact X5c. The timer motor TM is connected in series to the relay contact X61 of the sixth relay X6.

Next, regarding the operation, the basic principle of operation is carried out in the order of steps as shown in FIG. First, the sterilization process will be explained. After opening the lid 5, storing the objects to be sterilized such as syringe needles and forceps, and closing the lid, when AC power is supplied, the drive circuit D operates because the cutoff transistor TR3 in the limiter circuit LT is ON. At the same time, the first relay X1 operates and its relay contact X1s turns ON. Then, when the sterilization time is set by the timer device T according to the object to be sterilized, the first timer switch TS1 is turned ON, and the sterilization start switch ST2 is turned ON, the third relay X3 is activated, and the relay connected in parallel to the sterilization start switch ST2 is activated. Contact X3s turns ON and holds itself, and connects movable contact X3a of third relay X3 to one fixed contact X3b. Also, the 4th relay
The output transistor is activated by the output of the water level detection circuit WS through the movable contact X4a and the fixed contact X4c of 4.
The fifth relay X5 driven via TR7 opens its relay contact X5s, connects its movable contact X5a to one fixed contact X5b, opens the electromagnetic valve BV, and transfers the water in the water storage tank 3 to the pipe 4.
Water is injected into chamber 2 through the water injection indicator lamp.
Display the water injection status on PL4. Eventually, when water is poured into the bottom of the chamber 2 to a predetermined water level, the respective sensing electrodes 9 and 9' are short-circuited through the water, and the output of the water level sensing circuit WS is output from the output transistor TR7.
Turn off and turn on relay contact X5s of 5th relay
At the same time, the fourth relay X4 is driven and its movable contact X4a is connected to the other fixed contact X4b, and the sterilization heater control relay RY2 is connected via the movable contact PSa of the first pressure switch PS1 and one fixed contact PSc. Drives the relay contact RS2 of the relay.
Turn ON, energize the sterilization heater 6 to heat the water in the chamber 2, and then turn on the first pressure switch PS1.
Controlled by turning on and off. The ON operation of the first pressure switch PS1 controls the sixth relay X6, which turns ON the relay contact X61 to drive the timer motor TM to perform a timing operation, and the relay contact X62 of the motor is energized in conjunction with self-holding. The object to be sterilized is sterilized using saturated steam. At this time, relay contact X4s of the fourth relay X4 is turned ON.
Along with this, the sterilization indicator lamp PL1 lights up to indicate that sterilization is in progress. After the aforementioned predetermined water level is detected, the fifth relay X5 is de-energized and the relay contact Circuit VS comparator CP
The reference potential of the other input terminal of 2 becomes low. Therefore, the difference between the output potential of the amplifier AF and the output potential of the amplifier AF due to a change in the resistance value of the heat-sensitive element 10 during the sterilization process becomes small, and the limiter temperature becomes low. That is, in the case of abnormal heating where the sterilization heater 6 is continuously energized for some reason, the resistance value of the heat-sensitive element 10 decreases rapidly, and the output level of the increaser AF increases and the comparator of the potential comparator circuit VS. CP2 output is “L”
becomes “H” and drives the drive transistor TR2.
Turn on and turn off the cutoff transistor TR3, and the limiter circuit LT is cut off and the sterilization heater 6
Turn off the power to the

Eventually, when the timer motor TM reaches approximately 30 seconds before stopping, the second timer switch TS2 is turned ON, and the oscillation circuit DS turns the output transistor TR5 ON and OFF intermittently, causing the buzzer relay BX to operate intermittently and turning on the buzzer BZ. Blows intermittently. After that, the timer device T stops and the sterilization process ends, and since the second pressure switch PS2 is turned on, the movable contact X5a of the fifth relay X5, the other fixed contact X5c, and the other fixed contact of the third relay Solenoid valve via contact X3c and movable contact X3a
The BV is opened and the pressure difference causes water to drain and exhaust from the chamber 2 through the pipe 4, leaving the lid 5 in a half-open state.

The drying process will now be explained. When the aforementioned lid body 5 is half-open and the inside of the chamber 2 communicates with the outside air, the drying time is set by the timer device T, the first timer switch TS1 is turned on, and the drying start switch ST1 is turned on, the second relay is activated. When X2 is driven, its movable contact X2a is connected to fixed contact X2b and becomes in a self-holding state, and relay contact X2s is turned on and the drying indicator lamp PL3 is activated.
lights up. On the other hand, as the sixth relay X6 is driven, the relay contact The transistor TR1 is turned off, and the other input terminal of the comparator CP2 of the potential comparison circuit VS is connected to the resistors R4, R5, and the potential adjustment resistor VR, and the reference potential becomes high. Therefore,
Due to a change in the resistance value of the heat-sensitive element 10 during the drying process, the difference between the potential and the output potential of the amplifier AF becomes large, and the limiter temperature becomes high. The drying of the object to be sterilized is performed by the comparator of the temperature control circuit TC using the output of the amplifier circuit AP.
The drive transistor TR4 is driven through CP1 to drive the drying heater control relay RY1, and the relay contact RS1 is turned on to connect the sterilization heater 6 and the drying heater 7 in series, and cooperate with the sterilization heater 6 to control the chamber. Heat the inside of 2. After that, the amplifier circuit AP is activated based on the resistance value change of the heat-sensitive element 10.
and maintained at a predetermined temperature via the temperature control circuit TC. In the case of abnormal heating, the limiter circuit LT is activated by the output of the potential comparator circuit VS, as in the sterilization process described above.
cut off. Eventually, when the timer motor TM reaches approximately 30 seconds before stopping, the second timer switch is switched on.
TS2 turns on, turning on transistor TR8 and making buzzer BZ sound continuously. Thereafter, the timer device T stops and the drying process ends.

When performing the sterilization operation again immediately after the end of the drying process described above, although the resistance value of the heat-sensitive element 10 has become considerably large after the drying process is completed, the sterilization time is set using the timer device T and sterilization is started in the same manner as described above. When switch ST2 is turned on and solenoid valve BV is opened, water is injected into the chamber. At this time, the heat-sensitive element 10 is forcibly cooled by water accompanying the water injection operation, and when the water injection is completed, the resistance value is lowered to the value at the time of the sterilization process, and becomes below the limiter temperature at the time of sterilization.

As described above, the present invention includes a sterilization process in which the inside of the chamber is sealed, a heater is used to generate heat, and the object to be sterilized is sterilized with saturated steam, and the inside of the chamber is communicated with outside air and the air inside the chamber is heated by the heater to sterilize the object. It has a drying process for drying objects, and is supplied by the output of a temperature detection circuit that has a heat-sensitive element whose resistance value changes depending on the temperature, a potential comparison circuit that inputs one potential of a reference voltage circuit, and the output of the comparison circuit. A limiter circuit that cuts off the power supply, a heater control relay that is provided after the limiter circuit and that controls the heater, and a water level detection circuit that detects that water has been injected to the inner bottom of the chamber up to a predetermined level during sterilization and stops the completion of water injection. The heat-sensitive element is provided at the inner bottom of the chamber, and the reference voltage circuit switches its set potential by a water level detection circuit that detects completion of water injection, so that a single limiter circuit is provided. By changing the limiter temperature during sterilization and drying, it is possible to prevent abnormal heating during each process. In addition, even immediately after the drying process when the temperature inside the chamber is relatively high, the heat-sensitive element can be cooled with water injection, making it possible to return the limiter temperature to the sterilization temperature in a short time, allowing continuous sterilization and drying. It is very convenient if you do it.

[Brief explanation of drawings]

Fig. 1 is an external perspective view of the steam sterilizer of the present invention, Fig. 2 is an internal explanatory view, Fig. 3 is an overall circuit diagram, Fig. 4 is a main circuit diagram, and Fig. 5 is a process diagram. be. 2...Chamber, 6...Heater for sterilization, 7...Heater for drying, 10...Thermosensitive element, Ts...Temperature detection circuit, Vs...Potential comparison circuit, VA...Potential setting device,
LT...Limiter circuit, D...Drive circuit, RY1...
Drying heater control relay, RY2...sterilization heater control relay, WS...water level detection circuit, VT
...Reference voltage circuit.

Claims (1)

[Claims] 1 A sterilization process in which the inside of the chamber is sealed and a heater is used to generate heat to sterilize the object to be sterilized with saturated steam, and a drying process in which the inside of the chamber is communicated with outside air and the air inside the chamber is heated by a heater to dry the object to be sterilized. In a steam sterilizer, a potential comparison circuit inputs the output of a temperature detection circuit having a heat-sensitive element whose resistance value changes depending on temperature and one potential of a reference voltage circuit, and the power supply is cut off by the output of the comparison circuit. A drive circuit comprising a limiter circuit, a heater control relay that is provided after the limiter circuit and controls the heater, and a water level detection circuit that detects that water has been poured into the inner bottom of the chamber up to a predetermined water level during sterilization, The steam sterilizer is characterized in that the heat-sensitive element is provided at the inner bottom of the chamber, and the reference voltage circuit switches its set potential by a water level detection circuit that detects completion of water injection.