Vacuum exhaust system

Abstract

This vacuum exhaust system (1) is provided with an engine (30), a turbo-molecular pump (200), a rotary pump (250), a turbine (370), an exhaust gas pipe (32B), and a rotating shaft (38). The turbo-molecular pump (200) is connected to a chamber (10). The rotary pump (250) is provided on the downstream side of an exhaust passage of the turbo-molecular pump (200). The turbine (370) is connected to a rotor blade part (210) of the turbo-molecular pump (200). In the exhaust gas pipe (32B), the turbine (370) is provided, and exhaust gas from the engine (30) flows. The rotating shaft (38) is provided to rotate a rotor (270) of the rotary pump (250) by receiving power from the engine (30).

Description

Vacuum Pumping System

[0001] The present disclosure relates to vacuum pumping systems.

[0002] Japanese Patent Laid-Open Publication No. 6-283449 (Patent Document 1) discloses a vacuum pumping device. This device includes a turbomolecular pump and a dry pump as its auxiliary pump. The turbomolecular pump and the auxiliary pump are used to evacuate a vacuum chamber to an ultra-vacuum state.

[0003] Japanese Patent Application Publication No. 6-283449

[0004] Chambers such as those described above are commonly installed in factories and the like that manufacture precision components such as semiconductors or nanotechnology products. When the turbomolecular pump and the auxiliary pump are driven using electricity generated at a power plant such as a thermal power plant, the overall energy efficiency may be low. This is undesirable from the perspective of the environmental impact when evacuating the chamber in the factory and the like. With the increasing demand for precision components, there is a demand for technology that can reduce the environmental impact when evacuating the chamber in the factory and the like.

[0005] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide a vacuum pumping system that can reduce the environmental load when a chamber is evacuated.

[0006] The vacuum pumping system disclosed herein is a vacuum pumping system for evacuating a chamber. The vacuum pumping system includes an internal combustion engine, a turbomolecular pump, an auxiliary pump, a turbine, an exhaust gas pipe, and a rotating shaft. The turbomolecular pump is connected to the chamber. The auxiliary pump is provided downstream of an exhaust passage of the turbomolecular pump. The turbine is connected to a rotor portion of the turbomolecular pump. The exhaust gas pipe is provided with a turbine through which exhaust gas from the internal combustion engine flows. The rotating shaft is provided to rotate a rotor of the auxiliary pump by receiving power from the internal combustion engine.

[0007] With the above configuration, the turbine receives exhaust gas from the internal combustion engine and rotates, driving the turbomolecular pump (moving blade portion). Furthermore, the power of the internal combustion engine is transmitted to the rotor via the rotating shaft, causing the rotor to rotate and drive the auxiliary pump. This allows both the exhaust gas (exhaust loss) of the internal combustion engine and the power of the internal combustion engine to be effectively utilized for evacuating the chamber. As a result, the total energy efficiency during evacuating the chamber can be improved compared to an example in which the turbomolecular pump and the auxiliary pump are driven solely by electricity. Therefore, the environmental impact during evacuating the chamber can be reduced.

[0008] The vacuum exhaust system may further include a pipe provided in the chamber, through which the coolant that has passed through the internal combustion engine flows.

[0009] If a large number of water molecules are adsorbed on the inner wall surface of the chamber, the water molecules (moisture) inside the chamber may not be sufficiently discharged from the chamber during evacuation. This can lead to a situation where the chamber is not fully evacuated. The above configuration allows heat released from the refrigerant heated by the internal combustion engine (waste heat from the internal combustion engine) to be transferred to the inner wall surface of the chamber through the piping. This causes the water molecules to evaporate, avoiding the above situation and increasing the movement speed of air molecules and water molecules within the chamber. As a result, evacuation of the chamber can be more effectively promoted. Furthermore, in addition to the exhaust gas and power of the internal combustion engine, the waste heat (cooling loss) of the internal combustion engine is effectively utilized for evacuation, further improving energy efficiency during evacuation.

[0010] The vacuum exhaust system may further include a temperature sensor and a control device. The temperature sensor detects the temperature of the chamber. The control device controls the internal combustion engine according to the temperature. When the temperature is lower than a predetermined temperature, the control device executes first control to control the internal combustion engine at a retarded angle relative to a reference advance angle determined based on the combustion efficiency of the internal combustion engine.

[0011] With the above configuration, the internal combustion engine operates on the retard side, increasing the amount of waste heat from the internal combustion engine. This increases the amount of heat dissipated from the piping through which the refrigerant flows. As a result, the evaporation of the water molecules is promoted, and even when the ambient temperature is lower than a predetermined temperature, the internal space of the chamber can be heated more quickly using the waste heat from the internal combustion engine.

[0012] If the temperature exceeds the predetermined temperature after the first control, the control device may execute a second control that controls the internal combustion engine at a reference advance angle.

[0013] When the temperature of the chamber exceeds the predetermined temperature, it can be considered that the internal space of the chamber is sufficiently warmed and therefore it is no longer necessary to increase the waste heat of the internal combustion engine. By adopting the above configuration, the internal combustion engine operates at the reference advance angle, thereby increasing the combustion efficiency of the internal combustion engine (reducing the amount of waste heat). As a result, after the internal space of the chamber is sufficiently warmed, it is possible to continue to properly evacuate the chamber while saving fuel.

[0014] The vacuum pumping system may further include a power generator and an electric heating wire. The power generator generates electricity using power from the internal combustion engine. The electric heating wire is provided in the chamber, and electric power generated by the power generator is transmitted to the electric heating wire.

[0015] With the above configuration, even if a large number of water molecules are adsorbed on the inner wall surface of the chamber, the water molecules evaporate due to heat radiation from the heating wire. This prevents the chamber from being insufficiently evacuated due to the water molecules, and increases the movement speed of air molecules and water molecules within the chamber. As a result, the evacuation of the chamber can be more effectively promoted. Furthermore, the power of the internal combustion engine can be effectively used to drive the auxiliary pump as well as to radiate heat from the heating wire. As a result, the energy efficiency during evacuation of the chamber can be further improved.

[0016] The vacuum pumping system may further include a power generator and a control device. The power generator generates electricity using power from the internal combustion engine. The control device controls the internal combustion engine. The control device operates using the power generated by the power generator.

[0017] In order to properly evacuate the chamber, it is preferable that the internal combustion engine be controlled by a control device. With the above configuration, the power of the internal combustion engine can be effectively utilized for controlling the internal combustion engine in addition to driving the auxiliary pump. Additionally, various devices, such as the turbomolecular pump, the auxiliary pump, and the control device, operate using energy generated by the internal combustion engine (such as exhaust gas or the power of the internal combustion engine). This allows the vacuum pumping system to autonomously and properly evacuate the chamber while minimizing the power supplied from outside.

[0018] The vacuum pumping system may further include a power generator, a connecting shaft, and a motor. The power generator generates electricity using power from the internal combustion engine. The connecting shaft connects the turbine to the rotor blade portion. The motor is connected to the connecting shaft and operates to assist rotation of the connecting shaft using power generated by the power generator.

[0019] With the above configuration, the torque of the motor is further supplied to the connecting shaft, increasing the rotation speed of the rotor blades. This increases the output of the turbomolecular pump. As a result, it is possible to prevent excessive time from being required for evacuation when the capacity of the chamber is large. Furthermore, the power of the internal combustion engine can be effectively used to operate the motor in addition to driving the auxiliary pump.

[0020] According to the present disclosure, it is possible to reduce the environmental load when evacuating a chamber.

[0021] It is a diagram showing the overall configuration of a vacuum exhaust system according to an embodiment. It is a diagram showing the configuration of a cooling system. It is a diagram explaining how energy output by an engine is used for a vacuum exhaust device. It is a flowchart illustrating the procedure of a process executed by a control device in an embodiment. It is a diagram for explaining the function of a motor of a turbomolecular pump. It is a diagram for explaining a configuration for heating a chamber using power generated by an alternator.

[0022] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The same or corresponding parts in the drawings will be denoted by the same reference numerals, and the description thereof will not be repeated. The embodiments and their modifications may be combined with each other as appropriate.

[0023] FIG. 1 is a diagram showing the overall configuration of a vacuum exhaust system according to an embodiment. Referring to FIG. 1, vacuum exhaust system 1 is a system for evacuating chamber 10 and includes chamber 10, a temperature sensor 15, and a vacuum exhaust device 20. Vacuum exhaust system 1 further includes an engine 30, an operation unit 31, an intake gas pipe 32A, an exhaust gas pipe 32B, a crankshaft 33, pulleys 34 to 36, a belt 37, and rotating shafts 38 and 39. Vacuum exhaust system 1 further includes an alternator 40, an AC / DC converter 45, a battery 50, a radiator 70, and a control device 80.

[0024] The chamber 10 is installed in a factory or the like for manufacturing precision parts such as semiconductors or nanotechnology products. Manufacturing precision parts inside the chamber 10 (in a vacuum state) can prevent even minute impurities from remaining inside the parts. The inner wall surface of the chamber 10 is also referred to as the inner wall surface 12. The temperature sensor 15 detects the temperature TM of the chamber 10. In this example, the temperature TM is the ambient temperature inside the chamber 10, but it may also be the temperature of the inner wall surface 12.

[0025] The vacuum exhaust device 20 includes a turbomolecular pump 200 and a rotary pump (oil rotary vacuum pump) 250. The turbomolecular pump 200 is connected to the chamber 10 through a pipe 150 and includes a rotor blade section 210, a stator blade section 220, and a motor 230. The rotor blade section 210 is disposed opposite the stator blade section 220 and is composed of a plurality of rotor blades (not shown). When these rotor blades rotate at high speed, air from the chamber 10 is drawn into the intake port of the turbomolecular pump 200 through the pipe 150. The drawn air is blown out from the exhaust port of the turbomolecular pump 200 into a pipe 240 (exhaust passage). The function of the motor 230 will be described in detail later.

[0026] The rotary pump 250 is an auxiliary pump provided downstream of the exhaust passage of the turbomolecular pump 200 and assists the operation of the turbomolecular pump 200. For example, the rotary pump 250 enables stable evacuation of the turbomolecular pump 200 after it is started, or evacuates the chamber 10 before it is started. The rotary pump 250 includes a rotor 270. When the rotor 270 rotates, air in the piping 240 is drawn into the intake port of the rotary pump 250. The drawn air is blown out from the exhaust port of the rotary pump 250 into the piping 280. The rotary pump 250 may be replaced by another type of auxiliary pump, such as a dry pump. The chamber 10 can be evacuated to an ultra-vacuum state by operating both the vacuum exhaust device 20 and the rotary pump 250.

[0027] The engine 30 is an internal combustion engine (gasoline engine) that operates by consuming gasoline as fuel. The engine 30 has a cylinder 310, a piston 320, a cylinder head 325, and an ignition plug 330. The piston 320 is inserted within the cylinder 310 so as to be able to move up and down reciprocally. The space surrounded by the cylinder 310, the top of the piston 320, and the cylinder head 325 forms a combustion chamber of the engine 30. The ignition plug 330 is provided in the cylinder head 325.

[0028] The operation unit 31 receives a user operation to start the engine 30. This operation is also referred to as an "engine start operation." Intake air for the engine 30 flows into the intake gas pipe 32A. Exhaust gas from the engine 30 is discharged from the exhaust gas pipe 32B. A turbine 370 is provided in the exhaust gas pipe 32B, and the exhaust gas flows through the exhaust gas pipe 32B. The turbine 370 is connected to the rotor blade portion 210 of the turbomolecular pump 200 via a connecting shaft 245. In other words, the connecting shaft 245 connects the turbine 370 to the rotor blade portion 210 of the turbomolecular pump 200.

[0029] The crankshaft 33 is connected to the engine 30 and the pulley 34, and rotates in response to the reciprocating motion of the piston 320. The crankshaft 33 is connected to the rotor 270 of the rotary pump 250 via pulleys 34 and 35, a belt 37, and a rotating shaft 38. The pulley 34 is connected to pulleys 35 and 36 via a belt 37, and rotates by receiving the rotational force of the crankshaft 33. Each of the pulleys 35 and 36 rotates in conjunction with the pulley 34 (belt 37). The rotating shaft 38 is connected to the pulley 35 and the rotor 270, and rotates in conjunction with the pulley 35. The rotating shaft 38 receives power from the engine 30 via the crankshaft 33, the pulleys 35 and 36, and the belt 37 to rotate the rotor 270 (described in detail below), and corresponds to an example of a "rotating shaft" in the present disclosure. The rotary shaft 39 is connected to the pulley 36 and the alternator 40 and rotates in conjunction with the pulley 36 .

[0030] The alternator 40 is a power generating device that generates electricity using the power of the engine 30 (more specifically, the rotational force of the rotary shaft 39 resulting from the rotational force of the crankshaft 33). The AC / DC converter 45 converts the power (AC power) generated by the alternator 40 into DC power. The battery 50 is a secondary battery that can be charged by receiving this DC power. The radiator 70 is a component of a cooling system that cools the engine 30.

[0031] FIG. 2 is a diagram showing the configuration of a cooling system. Referring to FIG. 2, the cooling system 75 cools the engine 30 and is a component of the vacuum exhaust system 1, and includes a pipe 60 and a radiator 70. A coolant for cooling the engine 30 flows through the pipe 60. The radiator 70 is the same as that shown in FIG. 1 and cools the coolant by radiating heat from the coolant that has passed through the engine 30. A pipe 65 is a part of the pipe 60 and is provided in the chamber 10 (in this example, on its outer wall surface). The pipe 65 may be provided so as to pass through the chamber 10. In this case, the pipe 65 may be provided on the inner wall surface 12. The coolant that has passed through the engine 30 and has not yet been cooled by the radiator 70 flows through the pipe 65.

[0032] 1 , the control device 80 includes a processor 82 and a memory 84. The processor 82 is, for example, a CPU (Central Processing Unit) and executes various types of arithmetic processing. The memory 84 includes a ROM and a RAM (neither of which are shown). The ROM stores programs executed by the processor 82 and various types of data.

[0033] The control device 80 is a control panel for controlling the engine 30, and operates using the power generated by the alternator 40 (more specifically, the power stored in the battery 50). The control device 80 controls the engine 30, for example, in accordance with the temperature TM. The relationship between the temperature TM and the control of the engine 30 will be described in detail later. The control device 80 can set the rotation speed of the engine 30.

[0034] When the turbomolecular pump 200 and the rotary pump 250 are driven using electricity generated at a power plant such as a thermal power plant, the total energy efficiency may be low. This is undesirable in terms of the environmental impact when evacuating the chamber 10 in a factory or the like. With the increasing demand for precision components, there is a demand for technology to reduce the environmental impact when evacuating the chamber 10 in a factory or the like. Furthermore, it is important to reduce the running costs when evacuating the chamber 10. The vacuum pumping system 1 according to the embodiment has a configuration to address these issues. This point will be explained below.

[0035] 3 is a diagram illustrating how energy output by the engine 30 is used for the vacuum pumping device 20. Referring to FIG. 3, the chamber 10, the vacuum pumping device 20, and the engine 30 are shown as major components of the vacuum pumping system 1.

[0036] According to this embodiment, the turbine 370 receives exhaust gas from the engine 30 and rotates. This causes the connecting shaft 245 to rotate, and the rotor blade section 210 of the turbomolecular pump 200 receives the rotational force of the connecting shaft 245 and is driven. Furthermore, the power of the engine 30 (the rotational force of the crankshaft 33) is transmitted to the rotor 270 of the rotary pump 250 via the pulley 34, the belt 37, the pulley 35, and the rotary shaft 38, causing the rotor 270 to rotate and driving the rotary pump 250.

[0037] This allows both the exhaust gas (exhaust loss) of the engine 30 and the power (rotational force of the crankshaft 33) of the engine 30 to be effectively utilized for evacuating the chamber 10. As a result, compared to a comparative example in which the turbomolecular pump 200 and the rotary pump 250 are driven solely by electricity, the total energy efficiency during evacuating the chamber 10 can be improved (details will be described later). In addition, when electricity prices are high, the running costs during evacuating the chamber 10 can be reduced by driving the turbomolecular pump 200 and the rotary pump 250 using fuel consumption in the engine 30 as described above.

[0038] 2 again, a further advantage of the embodiment will be described. If a large number of water molecules (moisture) are adsorbed on the inner wall surface 12 of the chamber 10, the water molecules in the chamber 10 may not be sufficiently sucked into the turbomolecular pump 200, which may result in the chamber 10 not being sufficiently evacuated while the turbomolecular pump 200 and the rotary pump 250 are operating.

[0039] According to the vacuum exhaust system 1 of this embodiment, heat (engine waste heat) released from the refrigerant heated by the engine 30 is transferred to the inner wall surface 12 of the chamber 10 through the piping 65 (the piping 65 functions as an annealing device that provides heat to the chamber 10). This causes the water molecules to evaporate, avoiding the above-mentioned problem, and increases the movement speed (exhaust speed) of air molecules and water molecules within the chamber 10. As a result, the vacuum exhaust of the chamber 10 can be more effectively promoted. Furthermore, in addition to the exhaust gas and power (rotational force of the crankshaft 33) of the engine 30, the exhaust heat (cooling loss) of the engine 30 can be effectively utilized for the vacuum exhaust of the chamber 10. As a result, the total energy efficiency during the vacuum exhaust of the chamber 10 can be further improved.

[0040] In the following embodiment, we will consider how much the total energy efficiency during evacuation of the chamber 10 is improved compared to the comparative example described above (an example in which the turbomolecular pump 200 and the rotary pump 250 are driven solely by electricity).

[0041] First, let us consider the energy efficiency during evacuation of the chamber 10 in the comparative example. In the comparative example, the operating power of the turbomolecular pump 200 and the rotary pump 250 is derived from electricity generated at a power plant (in this example, a thermal power plant). This generated electricity is transmitted from the power plant to consumer facilities such as factories via power transmission lines and substations, and then converted into the operating power described above for consumption. Typically, in a thermal power plant, approximately 40% of the energy (primary energy) of fuels such as oil, coal, or liquefied natural gas is converted into generated electricity, and the remaining approximately 60% is wasted. Furthermore, of the generated electricity, electricity equivalent to a few percent of the primary energy is lost as power losses in the power transmission lines and substations. Therefore, the electricity transmitted from the power plant to the consumer facilities is less than 40% of the primary energy. In the comparative example, the consumer facilities are provided with separate motors for driving the turbomolecular pump 200 and the rotary pump 250, and the energy conversion efficiency of these motors is at best just over 80%. Therefore, in the comparative example, approximately 30% of the primary energy is consumed for evacuating the chamber 10 (driving the turbomolecular pump 200 and the rotary pump 250).

[0042] Next, let us consider the energy efficiency during evacuation of the chamber 10 in this embodiment. In this embodiment, approximately 30% to 40% of the input energy (fuel energy) of the engine 30 is consumed to rotate the crankshaft 33 (for example, approximately 30% is consumed to drive the rotary pump 250, and a few percent is consumed to drive the alternator 40). Approximately 30% of the input energy is lost to exhaust (for example, approximately 10% is consumed to drive the turbomolecular pump 200). Approximately 30% of the input energy is lost to cooling (for example, approximately 20% is lost to heat dissipation from the piping 65 to the chamber 10). Therefore, at least approximately 60 (= 30 + 10 + 20)% of the fuel is consumed to evacuation of the chamber 10 (to drive the turbomolecular pump 200 and the rotary pump 250, and to dissipate heat from the piping 65 to the chamber 10).

[0043] As described above, when considering the energy conversion efficiency in a thermal power plant, the total energy efficiency during evacuation of the chamber 10 in the embodiment can be approximately twice that of the comparative example, a significant improvement. Therefore, according to the embodiment, the environmental load during evacuation of the chamber 10 can be significantly reduced. This effect is particularly pronounced when the turbomolecular pump 200 and rotary pump 250 operate for long periods of time (e.g., 24 hours a day) in a factory or the like. Note that the ratios and other factors used in the above discussion are merely examples, and the actual values ​​may vary somewhat depending on various conditions. However, it is certain that the vacuum evacuation system 1 can reduce the environmental load during evacuation of the chamber 10.

[0044] An example of control of the engine 30 by the control device 80 will now be described. For example, if the temperature TM is lower than a predetermined temperature immediately after starting the engine 30, the control device 80 executes retard control. The retard control corresponds to controlling the engine 30 to be more retarded than a reference advance angle (in this example, controlling the ignition plug 330 so that ignition occurs later than a reference timing corresponding to the reference advance angle). The reference advance angle is determined by prior experiments or the like based on the combustion efficiency of the engine 30, and in this example, corresponds to the advance angle at which combustion efficiency is maximized.

[0045] According to the above-described retard control, ignition occurs in cylinder 310 with a delay from the reference timing. This reduces combustion efficiency and increases the amount of waste heat generated by engine 30. As a result, the amount of heat dissipated from pipe 65 (FIG. 2) increases, allowing water molecules on inner wall surface 12 to evaporate more effectively. This allows chamber 10 to be evacuated more effectively. Furthermore, even if temperature TM has dropped below a predetermined temperature, the internal space of chamber 10 can be quickly heated using the waste heat generated by engine 30.

[0046] If the temperature TM exceeds the predetermined temperature after starting the engine 30 (retardation control), the internal space of the chamber 10 is sufficiently warmed. Therefore, it can be considered that it is no longer necessary to increase the waste heat of the engine 30.

[0047] Therefore, the control device 80 may switch from the retard control to the normal control when the temperature TM exceeds a predetermined temperature after the retard control. The normal control corresponds to controlling the engine 30 at a reference advance angle (in this example, controlling the spark plug 330 so that it ignites at a reference timing).

[0048] According to the above configuration, after normal control starts, the engine 30 operates at the reference advance angle. This increases the combustion efficiency of the engine 30 (reducing the amount of waste heat). As a result, after the internal space of the chamber 10 has been sufficiently warmed, it is possible to continue to appropriately evacuate the chamber 10 while saving fuel.

[0049] 4 is a flowchart illustrating the procedure of the process executed by the control device 80 in this embodiment. This flowchart is started in response to the engine start operation described above. Hereinafter, steps will be abbreviated as "S."

[0050] 4, control device 80 determines whether temperature TM is less than a predetermined temperature (S10). If temperature TM is equal to or greater than the predetermined temperature (NO in S10), the process proceeds to S25. If temperature TM is less than the predetermined temperature (YES in S10), control device 80 executes retard control (S15).

[0051] After starting the retard control, the control device 80 determines whether the temperature TM exceeds a predetermined temperature (S20). If the temperature TM is less than the predetermined temperature (NO in S20), the process returns to S15, and the retard control continues. If the temperature TM exceeds the predetermined temperature (YES in S20), the control device 80 executes normal control instead of the retard control (S25). Then, the process ends.

[0052] 5 is a diagram for explaining the function of the motor 230 of the turbomolecular pump 200. Referring to Fig. 5, the inverter 55 is a component of the vacuum pumping system 1, and converts DC power from the battery 50 into AC power for the motor 230 in accordance with a command from the control device 80.

[0053] 1 and is connected to the connecting shaft 245 via a mechanical mechanism (not shown) such as a gear. The motor 230 operates using the power generated by the alternator 40 (more specifically, it is driven by the inverter 55, which consumes the power stored in the battery 50), and functions as an electric assist motor that assists the rotation of the connecting shaft 245. Specifically, when the motor 230 receives AC power from the inverter 55 and rotates, the torque of the motor 230 is further supplied to the connecting shaft 245 via the mechanical mechanism, thereby increasing the rotation speed of the connecting shaft 245. As a result, the output of the turbomolecular pump 200 is increased compared to an example in which the turbomolecular pump 200 (rotating blade section 210) is driven only by the turbine 370.

[0054] Driving the motor 230 as described above makes it possible to prevent excessive time from being required for evacuation when the capacity of the chamber 10 is large. Furthermore, because the motor 230 operates using the power generated by the alternator 40, the power of the engine 30 can be effectively used to operate the motor 230 in addition to driving the rotary pump 250.

[0055] As described above, according to the embodiment, the exhaust gas (exhaust loss), power, and exhaust heat (cooling loss) of the engine 30 are all effectively utilized for evacuating the chamber 10. As a result, the environmental load and running costs during the evacuation of the chamber 10 can be reduced.

[0056] In this embodiment, the control device 80 operates using the power generated by the alternator 40 (the power stored in the battery 50). Controlling the engine 30 is necessary to properly evacuate the chamber 10. With the above configuration, the power of the engine 30 (the rotational force of the crankshaft 33) can be effectively utilized to control the engine 30 in addition to driving the rotary pump 250. Additionally, various devices, such as the turbomolecular pump 200, the rotary pump 250, and the control device 80, operate using energy generated by the engine 30 (exhaust gas or the power of the engine 30 (specifically, the rotational force of the rotary shaft 38 or the power generated by the rotational force of the rotary shaft 39)). As a result, after the engine start operation, the vacuum pumping system 1 can autonomously and properly evacuate the chamber 10 while minimizing the amount of power it receives from an external source.

[0057] In the embodiment, the chamber 10 is heated using waste heat from the engine 30 (heat radiated from the pipe 65 in FIG. 2 ). However, as will be described below, the chamber 10 may be heated using electric power generated by the alternator 40.

[0058] Fig. 6 is a diagram illustrating a configuration for heating chamber 10 using power generated by alternator 40. Referring to Fig. 6, the vacuum exhaust system according to this modification differs from vacuum exhaust system 1 of the embodiment in that piping 65 is not provided in chamber 10 as in the example of Fig. 2 and that it further includes heating wire 90 and relay 92. However, in other respects, it is basically the same as vacuum exhaust system 1.

[0059] Electric power generated by the alternator 40 (more specifically, electric power stored in the battery 50) can be transmitted to the heating wire 90. The heating wire 95 is a part of the heating wire 90 and is provided on the chamber 10 (in this example, on the outer wall surface thereof). The heating wire 95 may be provided so as to pass through the chamber 10. In this case, the heating wire 95 may be provided on the inner wall surface 12.

[0060] The relay 92 is provided on the heating wire 90 and is turned on and off by the control device 80. For example, if the temperature TM immediately after the engine start operation is lower than the predetermined temperature, the control device 80 turns on the relay 92. This causes current from the battery 50 to flow through the heating wire 90.

[0061] As a result, even if a large number of water molecules are adsorbed on the inner wall surface 12 of the chamber 10 as described above, the water molecules evaporate due to heat radiation from the heating wire 95 (the heating wire 95 functions as an annealing device that provides heat to the chamber 10). This, as in the example of FIG. 2, can more effectively promote evacuation of the chamber 10. Furthermore, because a current derived from the power generated by the alternator 40 flows through the heating wire 90 (95), the power of the engine 30 (the rotational force of the crankshaft 33) is effectively used to drive the rotary pump 250 and also to radiate heat from the heating wire 95. As a result, the energy efficiency during evacuation of the chamber 10 can be effectively improved.

[0062] If the temperature TM exceeds a predetermined temperature after the control device 80 turns on the relay 92, the control device 80 may turn off the relay 92. This makes it possible to avoid overheating of the chamber 10 and conserve the power stored in the battery 50.

[0063] [Other Modifications] In the above, the turbomolecular pump 200 includes the motor 230, and the vacuum pumping system 1 includes the pipe 60 or the heating wire 95, but the motor 230, the pipe 60, or the heating wire 95 are not essential components. Even without these components, as long as the moving blade section 210 of the turbomolecular pump 200 is driven by the exhaust gas from the engine 30, and the rotor 270 of the rotary pump 250 is driven by the rotational force of the rotary shaft 38, the total energy efficiency can be improved.

[0064] The control device 80 may change the rotation speed of the engine 30 depending on the size (weight) of the rotor blade section 210 of the turbomolecular pump 200. For example, when driving a turbomolecular pump 200 having a larger size rotor blade section 210, the control device 80 may set the rotation speed of the engine 30 higher. This increases the amount of exhaust gas from the engine 30. As a result, it is possible to avoid a situation in which the driving force (rotational force) of the rotor blade section 210 decreases when the size of the rotor blade section 210 is large. The above sizes are stored in the ROM of the memory 84.

[0065] In the embodiment, the crankshaft 33 is indirectly connected to the rotor 270 of the rotary pump 250 via elements such as the pulleys 34 and 35, the belt 37, and the rotating shaft 38, but it may be directly connected to the rotor 270 without these elements. In this case, the crankshaft 33 is a rotating shaft for rotating the rotor 270, and corresponds to an example of the "rotating shaft" in the present disclosure, and the rotor 270 rotates by directly receiving the rotational force of the crankshaft 33.

[0066] In the embodiment, the crankshaft 33 is indirectly coupled to the rotor 270 of the rotary pump 250 via elements such as the pulleys 34 and 35, the belt 37, and the rotary shaft 38. However, the crankshaft 33 and the rotary shaft 38 may be indirectly coupled via a speed change mechanism such as a CVT (Continuously Variable Transmission) or an AT (Automatic Transmission), not shown. In this case, the speed change mechanism can control the rotation speed of the rotor 270 so as to coordinate with the rotation speed of the rotor blade section 210.

[0067] In the embodiment, the engine 30 is a gasoline engine, but it may be replaced by a diesel engine. Diesel engines generally have higher combustion efficiency and greater crankshaft rotational force than gasoline engines. Therefore, if fuel saving and using greater rotational force to rotate the rotary shafts 38, 39 are given priority, it is preferable to replace the engine 30 with a diesel engine. When the engine 30 is replaced by a diesel engine, the retard control corresponds to controlling the engine's fuel injection device so that fuel is injected later than a reference timing (the timing at which thermal efficiency is maximized) determined based on the thermal efficiency of the engine. The normal control corresponds to controlling the fuel injection device so that fuel is injected at the reference timing.

[0068] Gasoline engines generally generate more waste heat and have lower fuel consumption than diesel engines. As a result, a large amount of heat is dissipated from the pipe 65 (FIG. 2). Therefore, when the chamber 10 is large and quick warming of the chamber 10 (quick evaporation of water molecules on the inner wall surface 12) after the engine start operation is a priority, it is preferable to use a gasoline engine as the engine 30, as in the present embodiment.

[0069] Furthermore, the engine 30 may be replaced by a gas engine (gas heat pump). A gas heat pump can utilize existing infrastructure for fuel supply, and has thermal and power characteristics similar to those of a gasoline engine.

[0070] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0071] REFERENCE SIGNS LIST 1 Vacuum exhaust system 10 Chamber 20 Vacuum exhaust device 30 Engine 32A Intake gas pipe 32B Exhaust gas pipe 33 Crankshaft 38, 39 Rotating shaft 40 Alternator 50 Battery 60, 65, 150, 240, 280 Piping 80 Control device 90, 95 Heating wire 200 Turbo molecular pump 210 Rotor blade section 230 Motor 245 Connecting shaft 250 Rotary pump 270 Rotor

Claims

1. A vacuum pumping system for evacuating a chamber, comprising: an internal combustion engine; a turbomolecular pump connected to the chamber; an auxiliary pump provided downstream of an exhaust passage of the turbomolecular pump; a turbine connected to a rotor portion of the turbomolecular pump; an exhaust gas pipe in which the turbine is provided and through which exhaust gas from the internal combustion engine flows; and a rotating shaft that receives power from the internal combustion engine and rotates a rotor of the auxiliary pump.

2. The vacuum exhaust system according to claim 1, further comprising a pipe provided in said chamber through which a coolant that has passed through said internal combustion engine flows.

3. A vacuum exhaust system as described in claim 2, further comprising a temperature sensor that detects the temperature of the chamber, and a control device that controls the internal combustion engine in accordance with said temperature, wherein when said temperature is below a predetermined temperature, said control device executes a first control that controls the internal combustion engine at a retarded angle relative to a reference advance angle determined based on the combustion efficiency of the internal combustion engine.

4. The vacuum exhaust system according to claim 3, wherein, if the temperature exceeds the predetermined temperature after the first control, the control device executes a second control that controls the internal combustion engine at the reference advance angle.

5. The vacuum exhaust system according to claim 1, further comprising: a power generation device that generates electricity using the power of the internal combustion engine; and an electric heating wire that is provided in the chamber and to which the generated power of the power generation device is transmitted.

6. A vacuum exhaust system as described in claim 1 or claim 2, further comprising: a power generation device that generates electricity using the power of the internal combustion engine; and a control device that controls the internal combustion engine, wherein the control device operates using the power generated by the power generation device.

7. A vacuum exhaust system according to any one of claims 1 to 4, further comprising: a power generating device that generates electricity using the power of the internal combustion engine; a connecting shaft that connects the turbine to the rotor blade portion; and a motor connected to the connecting shaft that operates to assist the rotation of the connecting shaft using the power generated by the power generating device.

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