JPS647280Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a vacuum control device installed in an EPMA, SEM, etc. whose sample chamber is configured as a vacuum container.

Generally, in EPMA, SEM, electron microscopes, etc., it is necessary to irradiate the sample with an electron beam. A vacuum evacuation device is provided for pulling out the air. This vacuum evacuation device is equipped with an oil diffusion pump in addition to a rotary pump in order to create a high vacuum inside the vacuum container, and is equipped with a gate valve that communicates and closes both pumps and the vacuum container. Widely adopted. An oil diffusion pump heats oil with a heater to vaporize it, and uses a jet stream of the vaporized oil to adsorb and remove air in the atmosphere to create a vacuum higher than that of a rotary pump. In order for this oil diffusion pump to work effectively, it is necessary to operate the rotary pump and to keep cooling water flowing to cool the vaporized oil at all times. By the way, in a vacuum evacuation system equipped with such an oil diffusion pump, when the rotary pump stops due to a power outage, or the cooling water is cut off while the oil diffusion pump is operating, or when the oil diffusion pump is If the gate valve is left open when starting or stopping, vaporized oil will flow into the vacuum vessel and contaminate the vacuum vessel itself and the filament that generates the electron beam, making it impossible to analyze the sample. This causes the inconvenience of not being able to do so. For this reason, conventionally, when an abnormality like the one described above occurs or when the oil diffusion pump is started or stopped, the gate valve of the evacuation device has been manually opened or closed based on human judgment. but,
The timing of opening and closing the gate valve must be determined by always taking into account four conditions: the degree of vacuum inside the vacuum vessel, the temperature of the oil diffusion pump, whether cooling water is flowing, and whether the rotary pump is operating.
There are problems in that it is complicated and prone to malfunction.

The present invention was developed in view of the above problems, and is designed to open the gate valve when the oil diffusion pump or rotary pump is operating normally, and close the gate valve immediately when an abnormality occurs. Automate the opening and closing of gate valves,
It is an object of the present invention to provide a vacuum evacuation device in which the gate valve can be opened and closed reliably and the inside of the vacuum container can be kept clean for a long period of time.

EMBODIMENT OF THE INVENTION Hereinafter, the structure of this invention will be explained about an Example based on drawing.

In the figure, reference numeral 1 indicates a vacuum container installed in an analytical device such as EPMA or SEM, 2 indicates a vacuum evacuation device according to the present invention, 3 indicates a rotary pump, 4 indicates an oil diffusion pump, and 4a indicates an oil in the oil diffusion pump 4. 5 is a gate valve that communicates and closes the two pumps 3 and 4 and the vacuum vessel 2; 6 is a cooling pipe through which cooling water is passed to cool and liquefy the vaporized oil in the oil diffusion pump 4; be. Further, 7 is a vacuum sensor that detects the degree of vacuum inside the vacuum container 1 and outputs an ON signal when the degree of vacuum is higher than a predetermined degree of vacuum, and an OFF signal when the degree of vacuum is lower than a predetermined degree. 8 is ON when rotary pump 3 is operating
This is a rotary switch that outputs a signal and an OFF signal when stopped. 9 detects the temperature of the oil in the oil diffusion pump 4, and turns ON when the temperature is higher than a predetermined temperature.
10 is a thermo switch that outputs an OFF signal when the temperature is lower than a predetermined temperature, and 10 is a flow chart that outputs an ON signal when the cooling water in the cooling pipe 6 is flowing, and an OFF signal when it is stopped. It's a switch. 12 is the vacuum sensor 7, rotary switch 8, and thermoswitch 9.
It is a control means that inputs each output signal from the flow switch 10 and controls the gate valve 5 and the heater 4a of the oil diffusion pump 4. It is composed of parts 16, 18, 20, and 22. The receiving section 14 includes a vacuum sensor 7, a rotary switch 8,
It directly receives ON and OFF signals output from the thermo switch 9 and flow switch 10, and outputs the received signals to each of the first to fourth output sections 16, 18, 20, and 22. Among the output signals from the receiving section 14, the first output section 16 outputs the gate valve when the output signals of the rotary switch 8 and the flow switch 10 are both ON signals and the output signals of the vacuum sensor 7 and thermoswitch 9 are both OFF signals. 5 is released. Second output section 18
Of the output signals of the receiving section 14, the vacuum sensor 7,
When the signals of the rotary switch 8 and the flow switch 10 are both ON signals and the output signal of the thermoswitch 9 is an OFF signal, the gate valve 5 is closed and the heater 4a of the vacuum diffusion pump 4 is energized. The third output section 20 includes the receiving section 1
When output signals from the vacuum sensor 7, rotary switch 8, thermoswitch 9, and flow switch 10 are all ON signals, the gate valve 5 is opened and the heater 4a is energized. The fourth output section 22 closes the gate valve 5 when at least one of the rotary switch 8 and the flow switch 10 is an OFF signal among the output signals from the receiving section 14, and also closes the gate valve 5 and closes the heater 4a.
It also cuts off the electricity supply.

Next, the operation of the vacuum control device 2 having the above configuration will be explained.

Before the vacuum control device 2 is activated, the inside of the vacuum container 1 is at atmospheric pressure, the water in the rotary pump 3 and the cooling pipe 6 are both stopped, and the oil in the oil diffusion pump 4 is also cold. It is also assumed that the gate valve 5 is also closed. To evacuate the vacuum container 1 from this state, first turn on the power using the main switch (not shown), the rotary pump 3 will operate, and the cooling water in the cooling pipe 6 will be pumped by the water supply pump (not shown). The fluid is circulated. Therefore, the rotary switch 8 and the flow switch 10 output ON signals. Furthermore, since the inside of the vacuum container 1 is at atmospheric pressure and the oil diffusion pump 4 is not operating, both the vacuum sensor 7 and the thermoswitch 9 output OFF signals.
These output signals are sent via the receiving section 14 of the control means 12 to each of the first to fourth output sections 16, 18,
20 and 22, but the above combination is ON,
Since only the first output section 16 responds to the OFF signal, this first output section 16 is connected to the gate valve 5.
to open. As a result, the vacuum container 1 is first evacuated by the rotary pump 3. Vacuum container 1
The degree of vacuum inside increases, and the specified degree of vacuum, e.g.
When the temperature reaches 300μmHg, the output signal of the vacuum sensor 7 becomes
Changes from OFF signal to ON signal. Since the other conditions continue, both the rotary switch 8 and the flow switch 10 output an ON signal, and the signal from the thermoswitch 9 is an OFF signal. These signals are transmitted via the receiving section 14 to the first to fourth
However, only the second output section 18 responds to the above combination of ON and OFF signals. Therefore, the second output section 18 partially closes the gate valve 5 and energizes the heater 4a of the oil diffusion pump 4. The oil is heated by the heater 4a to a predetermined temperature (for example,
(45°C) or higher, the output signal from thermoswitch 9 changes from an OFF signal to an ON signal. As a result, the output signals of the thermo switch 9, the vacuum sensor 7, the rotary switch 8, and the flow switch 10 all become ON signals and are input to the receiving section 14.
of the above combinations input via the receiving section 14.
Since only the third output section 20 responds to the ON and OFF signals, the third output section 20 opens the gate valve 5 and continues to energize the heater 4a. As a result, the inside of the vacuum container 1 is drawn to a high vacuum by the oil diffusion pump 4 and the rotary pump 3. In this way, the inside of vacuum container 1 is 1×
When the vacuum level is about 10 ^-4 Torr, a steady state is reached and a high vacuum level is maintained. When the cooling water in the rotary pump 3 or cooling pipe 6 stops due to a power outage or water outage during vacuuming, or when the analyzer is stopped, at least one of the rotary switch 8 or the flow switch 10 will send an OFF signal. Therefore, this OFF signal is transmitted via the receiving section 14 to the fourth
It is input to the output section 22. As a result, the fourth output section 22 immediately closes the gate valve 5 to prevent the vaporized oil in the oil diffusion pump 4 from flowing into the vacuum container 1, and also cuts off the power supply to the heater 4a. Note that it is also possible to apply a microcomputer to the control means 12 consisting of the receiving section 14 and each of the first to fourth output sections 16, 18, 20, and 22.

As described above, according to the present invention, when the rotary pump and oil diffusion pump are operating normally, the gate valve is opened, and when the rotary pump stops or the cooling water stops flowing while the oil diffusion pump is operating, the gate valve is opened. The opening and closing operations of the gate valve are automated so that the gate valve is immediately closed when an error occurs or when an analyzer such as an EPMA is stopped. Therefore, the gate valve can be opened and closed reliably without causing malfunctions such as mistakes in the timing of opening and closing the gate valve as in the prior art. This prevents the vaporized oil in the oil diffusion pump from flowing into the vacuum container, resulting in excellent effects such as keeping the inside of the vacuum container clean for a long time.

[Brief explanation of the drawing]

The drawing is a block diagram showing the vacuum container and the entire vacuum evacuation device of the present invention. 1...Vacuum container, 2...Evacuation device, 3...Rotary pump, 4...Oil diffusion pump, 4a...Heater, 5
...Gate valve, 6...Cooling pipe, 7...Vacuum sensor, 8...Rotary switch, 9...Thermo switch, 1
0...Flow switch, 14...Receiving section, 16...First
Output section, 18...second output section, 20...third output section,
22...Fourth output section.

Claims (1)

[Scope of utility model registration request] A device equipped with a rotary pump and an oil diffusion pump that evacuate the inside of a vacuum container, and a gate valve that communicates and closes these pumps and the vacuum container, detects the degree of vacuum in the vacuum container and controls the When the degree of vacuum is higher than that, the ON signal is turned on.
A vacuum sensor that outputs an OFF signal when the temperature is low, a rotary switch that outputs an ON signal and an OFF signal when the rotary pump starts or stops, and a vacuum sensor that detects the temperature of the oil in the oil diffusion pump and detects the temperature when the temperature exceeds a predetermined temperature. A thermo switch that outputs an ON signal when the temperature is below a predetermined temperature and an OFF signal when the temperature is below a predetermined temperature, a flow switch that outputs an ON signal and an OFF signal when the flow of cooling water in the cooling pipe stops, the vacuum gauge sensor, and a rotary switch. , a receiving section that receives each output signal from the thermo switch and the flow switch, and among the signals received by this receiving section, the signals of the rotary switch and the flow switch are both ON signals, and the signals of the vacuum sensor and thermo switch are OFF signals. When the first output section opens the gate valve, the signals of the vacuum sensor, rotary switch, and flow switch are ON signals, and the signal of the thermo switch is ON.
When the OFF signal is present, the gate valve is closed, and the signals of the second output section that energizes the heater for heating the oil provided in the oil diffusion pump, the vacuum sensor, the rotary switch, the thermo switch, and the flow switch are all ON. When the signal is received, the third output section opens the gate valve and energizes the heater of the oil diffusion pump, and at least one of the rotary switch and the flow switch is turned off.
a fourth gate valve that closes the gate valve when the signal is received;
A vacuum evacuation device characterized by being provided with an output section.