JP4745779B2 - Vacuum equipment - Google Patents

Description

  The present invention relates to a vacuum apparatus, and more particularly to a vacuum apparatus including a mechanical vacuum pump that compresses gas sucked from an intake port to atmospheric pressure and discharges the gas from the exhaust port.

  In this type of vacuum apparatus, there is a conventional one disclosed in Patent Document 1, for example, in order to reduce driving power (power consumption) of a vacuum pump. According to this prior art, an auxiliary pump is connected to the last exhaust chamber of a vacuum pump, for example, a multistage roots type dry pump. The auxiliary exhaust pump depressurizes the last exhaust chamber, so that the burden on the rotor responsible for the last compression is reduced, and the driving power of the vacuum pump is reduced.

  In the prior art, a check valve having a forward direction to the atmosphere is provided at the outlet of the exhaust pipe connected to the exhaust chamber at the last stage, and an auxiliary pump is connected in parallel to the check valve. This configuration is also disclosed. Also with this configuration, the burden on the rotor at the last stage is reduced, so that the driving power of the vacuum pump is reduced. Even if the auxiliary pump fails, the exhaust gas flows through the check valve, so that the performance of the vacuum pump itself is maintained.

Japanese Patent Laid-Open No. 2003-155988

  By the way, in the above-mentioned prior art, the diaphragm pump whose rated electric power is 100 [W] is illustrated as an auxiliary pump. Further, it is disclosed that other dry pumps such as a vane pump, a piston pump, and a scroll pump may be used in addition to the diaphragm pump. That is, in the prior art, it is assumed that the auxiliary pump is a mechanical pump having a mechanically operated portion. For this reason, in addition to the vacuum pump, the auxiliary pump requires the same level of maintenance as the vacuum pump. Also, electric power for driving the auxiliary pump is required. Therefore, there is a problem that the running cost is increased and the meaning of providing the auxiliary pump is reduced.

  Further, when exhausting, for example, corrosive gas, flammable gas (including explosive gas), harmful gas, or the like according to the above-described conventional technology, these gases are diluted with a predetermined purge gas. It is necessary to perform a gas purge process. In this case, a separate facility for performing the gas purging process is required, and accordingly, the configuration of the entire vacuum apparatus becomes complicated and the initial cost increases.

  Therefore, an object of the present invention is to provide a vacuum apparatus that can reduce the driving power of a vacuum pump with a simpler and cheaper configuration than the prior art and that can also perform a gas purge process at the same time.

In order to achieve such an object, the vacuum device of the present invention includes a mechanical vacuum pump that compresses the gas sucked from the intake port to atmospheric pressure and discharges it from the exhaust port, and one end of the vacuum pump at the exhaust port. An exhaust pipe that is coupled to transfer the gas discharged from the exhaust port to the other end, and a check valve provided in the exhaust pipe with the direction from one end to the other end of the exhaust pipe as a forward direction; It comprises. Further, the exhaust pipe is connected to the upstream side of the check valve of the exhaust pipe. The ejector that sucks in the gas from the upstream side by supplying the driving gas and discharges the sucked gas together with the driving gas, and the discharge gas discharged from the ejector. And a joining pipe that joins the exhaust pipe to the downstream side of the check valve of the exhaust pipe. A purge gas for applying a gas purge process to the gas exhausted by the vacuum pump is used as a drive gas for driving the ejector.

That is, a space to be exhausted, for example, a vacuum chamber, is coupled to the suction port of the vacuum pump in the present invention . The vacuum pump sucks the gas in the vacuum chamber through the intake port and compresses it to atmospheric pressure. The compressed gas is discharged from the exhaust port of the vacuum pump, and the discharged gas, that is, the exhaust gas is transferred toward the other end of the exhaust pipe through the exhaust pipe having one end coupled to the exhaust port. For example, the exhaust gas is sent to a detoxifying device for detoxifying the exhaust gas. A check valve is provided in the middle of the exhaust pipe with the direction from one end to the other as the forward direction. And the ejector is couple | bonded upstream from the position in which the said nonreturn valve is provided of exhaust piping. The ejector sucks exhaust gas from the upstream side by supplying the driving gas. In other words, the ejector exhausts a space from the exhaust port of the vacuum pump to the check valve via a part of the exhaust pipe (a part upstream of the check valve). As a result, the vicinity of the exhaust port of the vacuum pump is evacuated, and the pressure difference between the exhaust port and the intake port of the vacuum pump is reduced. As a result, the load applied to the vacuum pump is reduced, and the driving power of the vacuum pump is reduced.

  On the other hand, the exhaust gas sucked into the ejector is discharged from the ejector together with the driving gas. Then, the discharged so-called discharged gas passes through the merging pipe and is joined downstream from the position where the check valve of the exhaust pipe is provided. Here, the discharge gas includes the drive gas for driving the ejector as described above, and a purge gas is used as the drive gas. Therefore, a gas purge process of diluting the exhaust gas is realized by joining the discharge gas containing the purge gas to the exhaust gas flowing through the exhaust pipe.

  In the present invention, the ejector may have an exhaust capability (exhaust speed) smaller than that of the vacuum pump. That is, the ejector according to the present invention functions as a so-called auxiliary pump that reduces the driving power of the vacuum pump by reducing the pressure in the vicinity of the exhaust port of the vacuum pump as described above. Therefore, the ejector does not require the exhaust capability as much as the vacuum pump, and it is sufficient if the ejector has the necessary and sufficient exhaust capability as the auxiliary pump. Therefore, by adopting an ejector having a relatively small exhaust capacity as such an auxiliary pump, the initial cost of the entire vacuum apparatus can be further reduced. Also, the smaller the ejector's exhaust capacity, the smaller the amount of drive gas consumed, so the running cost is reduced accordingly.

  And as a vacuum pump in this invention, a screw type dry pump is suitable, for example. That is, the screw-type dry pump alone has a driving power as the intake pressure (pressure on the intake port side) decreases, that is, as the pressure difference between the intake port and the exhaust port increases. Has a characteristic of increasing. Even when such a screw-type dry pump is employed as the vacuum pump of the present invention, as described above, the vicinity of the exhaust port of the dry pump is decompressed by the ejector. Therefore, even if the intake pressure of the dry pump decreases, the pressure difference between the intake port and the exhaust port does not increase as much as the single unit, and the drive power of the dry pump is reduced accordingly. That is, when a screw-type dry pump in which the driving power increases as the intake pressure decreases is adopted as a vacuum pump, the effect of reducing the driving power by the ejector appears more remarkably.

  Needless to say, the present invention is particularly effective when exhausting a gas that requires a gas purge process, such as a gas containing a corrosive gas, a flammable gas, or a harmful gas.

Then, as the driving gas in the present invention, for example, nitrogen (N ₂₎ gas is preferred. That is, in a place where a vacuum apparatus such as the present invention is used, for example, a factory or the like, the supply of nitrogen gas is generally provided, so that the nitrogen gas can be obtained relatively easily. Therefore, if nitrogen gas available from such existing equipment is adopted as the driving gas, the present invention can be realized more easily and inexpensively.

  Moreover, you may employ | adopt the compressed air (compressed dry air) compressed with the air compressor as drive gas. That is, in the above-described factories and the like, in addition to the nitrogen gas supply facility, there are many places where a compressed air supply facility is provided. Therefore, adopting such compressed air as the drive gas for the ejector is also a good measure for realizing the present invention easily and inexpensively. However, when the exhaust gas is a combustible gas (particularly explosive gas), it is desirable to use an inert gas such as nitrogen gas as the driving gas.

  Furthermore, for example, in order to make the entire vacuum device of the present invention explosion-proof, an explosion-proof product (a so-called explosion-proof test product that has passed the explosion-proof test) may be employed as the vacuum pump. That is, in the present invention, the ejector as the auxiliary pump does not include an explosion factor. Therefore, if an explosion-proof product is used for the vacuum pump as the main pump, the entire vacuum device can be made explosion-proof. On the other hand, in the above-described prior art, in order to make the entire device explosion-proof, not only the vacuum pump but also the auxiliary pump needs to be explosion-proof, and the configuration of the entire device is complicated accordingly. And increase the cost. In other words, according to the present invention, the explosion-proof vacuum device can be configured more simply and at a lower cost than in the past.

  According to the present invention, an ejector that is a so-called injection pump is used as an auxiliary pump for reducing the driving power of the vacuum pump. Therefore, the running cost including the maintenance cost and the like of the auxiliary pump can be significantly reduced as compared with the above-described conventional technology on the assumption that the auxiliary pump is a mechanical pump. Moreover, a purge gas is used as a drive gas for driving the ejector, and a gas purge process is actually performed by the discharge gas from the ejector including the purge gas. On the other hand, in the above-described prior art, in order to perform the gas purge process, a dedicated facility is separately required. That is, according to the present invention, the driving power of the vacuum pump can be reduced with a simpler and cheaper configuration than the conventional one, and the gas purge process can be simultaneously performed.

An embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 1, the vacuum apparatus 10 according to this embodiment includes a screw-type dry pump 12. The dry pump 12 incorporates a pair of single-stage rotors 16 that are rotated in opposite directions by a DC motor 14, and sucks gas from the intake port 18 by the rotation of the rotor 16. The sucked gas is transferred from the leading end 16a of the rotor 16 to the final end (also referred to as final stage or final compression step) 16b, and is compressed to atmospheric pressure at the final end 16b. The compressed gas is exhausted to the outside through the exhaust port 20. The tooth shape of the rotor 16 is arbitrary, and may be, for example, any of a Rishorum shape, a square screw shape, and a trapezoidal shape.

The intake port 18 of the dry pump 12 is coupled to, for example, an exhaust port of a vacuum tank (not shown) that constitutes a surface treatment device together with the vacuum device 10 of this embodiment . On the other hand, one end of the main exhaust pipe 22 is coupled to the exhaust port 20, and the other end of the main exhaust pipe 22 is coupled to, for example, an abatement apparatus (not shown).

  Further, a check valve 24 is provided in the middle of the main exhaust pipe 22 with the direction from one end (the dry pump 12 side) to the other end (the abatement apparatus side) of the main exhaust pipe 22 as a forward direction. . Further, a bypass pipe 28 having an air ejector 26 is provided in parallel with the check valve 24.

  Specifically, the bypass pipe 28 is an ejector 26, a suction side branch pipe 30 having one end coupled to the suction port 26a of the ejector 26, and a junction pipe having one end coupled to the discharge port 26b of the ejector 26. A discharge side branch pipe 32. The other end of the suction side branch pipe 30 is upstream of the position where the check valve 24 of the main exhaust pipe 22 is provided, in other words, from the check valve 24 to one end of the main exhaust pipe 22 (exhaust port 18). It is connected at an arbitrary position up to the connecting portion). On the other hand, the other end of the discharge side branch pipe 32 is downstream of the position where the check valve 24 of the main exhaust pipe 22 is provided, that is, from the check valve 24 to the other end (exhaust port) of the main exhaust pipe 22. It is connected at any position between.

Further, the ejector 26 has a supply port 26c to which driving gas for driving the ejector 26 is supplied. The supply port 26c is coupled to a nitrogen gas pipe (not shown). The nitrogen gas pipe referred to here means a pipe through which a relatively high pressure (for example, about 10 ⁶ [Pa]) nitrogen gas flows, and the nitrogen gas pipe is a vacuum apparatus according to this embodiment. If it is a place where 10 is used, such as a factory, it is generally deployed.

  The vacuum apparatus 10 configured as described above operates as follows.

  That is, it is assumed that the dry pump 12 is activated and the drive gas is supplied to the ejector 26. Then, the rotor 16 of the dry pump 12 rotates and gas is sucked from the vacuum chamber through the intake port 18. The sucked gas is transferred from the leading end 16a of the rotor 16 toward the final end 16b as described above, and is compressed to atmospheric pressure at the final end 16b. The compressed gas is discharged to the main exhaust pipe 22 via the exhaust port 20. Then, the exhausted gas, that is, the exhaust gas is sent to the abatement device through the main exhaust pipe 22 and further through the check valve 24 as shown by a dotted arrow 50 in FIG.

  On the other hand, the driving gas supplied to the ejector 26 is discharged from the discharge port 26 b of the ejector 26. Then, the gas discharged from the ejector 26 (discharge port 26b), that is, the discharge gas, passes through the discharge side branch pipe 32 on the downstream side of the check valve 24, as shown by a one-dot chain line arrow 52 in FIG. The main exhaust pipe 22 is joined. The discharge gas joined to the main exhaust pipe 22 is sent to the abatement apparatus together with the exhaust gas flowing through the main exhaust pipe 22.

Here, the drive gas for the ejector 26 is procured from the existing nitrogen gas pipe as described above. Since the pressure of the nitrogen gas flowing through the nitrogen gas pipe is relatively high (about 10 ⁶ [Pa]) as described above, it is sufficient to drive the ejector 26. However, the exhaust capacity of the ejector 26 is not large compared to the exhaust capacity of the dry pump 12. Therefore, for a while after the exhaust operation is started (dry pump 12 is activated), that is, while a relatively large amount of exhaust gas is being discharged from the dry pump 12, most of the exhaust gas is the main exhaust. It flows through the pipe 22 and does not flow toward the ejector 26 (bypass pipe 28). In other words, the ejector 26 does not perform its original function (as a pump). However, since the ejector 26 is provided in the bypass pipe 28, the ejector 26 does not become a pipe resistance against the exhaust action by the dry pump 12. Even in a situation where the ejector 26 does not function as a pump in this way, the drive gas supplied to the ejector 26 is discharged from the ejector 26 in the manner described above, and finally, the main exhaust gas is discharged. The exhaust gas flowing through the pipe 22 is merged.

  When the exhaust operation progresses and the amount of exhaust gas discharged from the dry pump 12 becomes relatively small, in detail, when the exhaust can be exhausted by the ejector 26, the ejector 26 is automatically activated. As a result, the exhaust gas discharged from the dry pump 12 passes through the suction side branch pipe 30 of the bypass pipe 28 and is sucked into the ejector 26 (suction port 26a) as shown by a two-dot chain line arrow 54 in FIG. It is. The sucked exhaust gas is discharged from the ejector 26 (discharge port 26b) together with the drive gas supplied to the ejector 26 (supply port 26c). The discharged discharge gas is finally joined to the exhaust gas flowing through the main exhaust pipe 24 as described above.

When the ejector 26 is thus activated, the ejector 26 is reversed from the exhaust port 20 of the dry pump 12 through a part of the main exhaust pipe 22 (a part upstream of the check valve 24). The space up to the stop valve 24 is exhausted. As a result, the space including the exhaust port 20 is depressurized, for example, a vacuum of about 8 × 10 ³ [Pa]. Since the exhaust port 20 is evacuated in this way, the pressure difference between the exhaust port 20 and the intake port 18, in other words, between the final end 16b and the leading end 16a of the rotor 16 is reduced. As a result, the load applied to the rotor 16 is reduced, and the driving power of the dry pump 12 is reduced.

FIG. 2 shows the power characteristics of the entire vacuum apparatus 10 of this embodiment . For reference, power characteristics when the dry pump 12 is a single unit are also shown.

That is, in FIG. 2, the solid curve X indicates the power characteristic of the dry pump 12 alone. As can be seen from this curve X, with the dry pump 12 alone, the driving power is minimized when the intake pressure is substantially equal to the atmospheric pressure (about 10 ⁵ [Pa]). The driving power increases as the intake pressure decreases (as it proceeds from the right side to the left side on the horizontal axis in FIG. 2), that is, as the exhausting operation proceeds. Further, when the intake pressure falls below a certain value (in FIG. 2, it is read as about 3 × 10 ³ [Pa], but this value varies depending on the exhaust capacity of the dry pump 12), the driving power is almost saturated. In the vicinity of the ultimate pressure, the driving power becomes maximum.

On the other hand, according to the vacuum apparatus 10 in which the ejector 26 is combined with the dry pump 12, when the intake pressure is substantially equal to the atmospheric pressure (about 10 ⁵ [Pa]), that is, immediately after the start of the exhaust operation, the ejector 26 is As in the case of the dry pump 12 alone, the driving power is minimized. The ejector 26 is activated while the exhaust operation proceeds and the intake pressure is reduced. As a result, as indicated by the dashed curve Y, the driving power starts from increasing to decreasing. Then, as the intake pressure decreases, the driving power further decreases, and the driving power becomes minimum near the ultimate pressure. That is, by adding the ejector 26 as an auxiliary pump to the screw-type dry pump 12 in which the driving power increases as the intake pressure decreases, the increase in the driving power is greatly suppressed. . In other words, according to the vacuum device 10 of this embodiment in which the screw-type dry pump 12 and the ejector 26 as an auxiliary pump are combined, when the intake pressure is relatively high, depending on the characteristics of the dry pump 12 itself. When the driving power is suppressed and the intake pressure is low, a complementary relationship is established in which the driving power is reduced by the ejector 26.

As described above, according to the vacuum device 10 of this embodiment , the drive power of the dry pump 12 is greatly reduced by combining the ejector 26 as the auxiliary pump with the screw type dry pump 12. In addition, since the ejector 28 that is an injection pump has durability and reliability that cannot be compared with a mechanical pump, according to this embodiment in which the ejector 26 is used as an auxiliary pump, the mechanical pump is Compared to the above-described conventional technology employed as an auxiliary pump, the running cost including the maintenance cost of the auxiliary pump can be greatly reduced. Moreover, since the nitrogen gas available from the existing nitrogen gas piping is used as the drive gas for the ejector 26, no special equipment for supplying the drive gas is required.

Further, the nitrogen gas as the driving gas is discharged from the ejector 26 and then merged with the exhaust gas flowing through the main exhaust pipe 22. Therefore, for example, even if exhaust gas contains gas that requires gas purge processing such as corrosive gas, flammable gas, or harmful gas, these gases are inevitably purged by the nitrogen gas. Is done. That is, according to this embodiment , the gas purge process can be performed simultaneously with the exhaust process.

In this embodiment , the nitrogen gas available from the existing nitrogen gas pipe is used as the drive gas for the ejector 26, but the present invention is not limited to this. For example, the nitrogen gas may be directly supplied to the ejector 26 from a nitrogen gas cylinder or a nitrogen gas generating device, not from the nitrogen gas pipe. Further, instead of nitrogen gas, other inert gas such as argon (Ar) gas or helium (He) gas may be employed as the driving gas.

Furthermore, instead of the inert gas, compressed air by an air compressor may be employed as the drive gas for the ejector 26. That is, in a factory or the like in which the vacuum apparatus 10 of this embodiment is used, not only nitrogen gas supply equipment but also such compressed air supply equipment is often provided, so that the compressed air is driven for the ejector 26. Employing the gas as a gas is also a good measure for realizing the vacuum apparatus 10 of this embodiment simply and inexpensively.

However, when the exhaust gas includes a combustible gas (particularly explosive gas), it is desirable to employ an inert gas such as nitrogen gas as the drive gas for the ejector 26. Further, instead of simply diluting the exhaust gas, a gas for neutralizing the exhaust gas may be employed as the driving gas. And of course, the vacuum apparatus 10 of this embodiment can be applied also to the use which does not require a gas purge process.

  In addition, even if any gas is adopted as the driving gas, the pressure must be at least a pressure that allows the ejector 26 to function as an auxiliary pump. In other words, the pressure of the driving gas only needs to be a level necessary and sufficient to cause the ejector 26 to function as an auxiliary pump. Further, as described above, the ejector 26 as an auxiliary pump does not require the exhaust capability as much as the dry pump 12, and has an exhaust capability of, for example, about several [%] to several tens [%] of the dry pump 12. If it is, it is enough.

  Furthermore, instead of the screw-type dry pump 12 described above, other positive displacement pumps such as a multi-stage roots pump and a multi-stage claw pump may be used.

Moreover, although it was set as the structure which couple | bonds the abatement apparatus which is not shown in figure with the other end of the main exhaust piping 22, it is not restricted to this. For example, instead of the detoxifying device, various processing devices such as a catalytic device for detoxifying exhaust gas by catalytic action and a dust collecting device for removing impurities contained in the exhaust gas may be provided. . Moreover, the other end of the main exhaust pipe 22 may be opened to the atmosphere without providing these processing devices. In this case, as the length of the main exhaust pipe 22 (the length from the joint portion with the bypass pipe 28 (discharge side branch pipe 32) to the other end (exhaust port)) becomes longer (several [m] or more), this embodiment The gas purging process due to is effective.

Furthermore, although the dry pump 12 in this embodiment uses the DC motor 14 as a drive source, the dry pump 12 may use an AC motor as a drive source.

In this embodiment , by adopting an explosion-proof product as the vacuum pump 12, the entire vacuum device 10 can be made to be explosion-proof. That is, since the ejector 26 as an auxiliary pump does not include an explosion factor, it can be adapted to the explosion-proof specification by adopting an explosion-proof product for the vacuum pump as a main pump. On the other hand, in the above-described prior art, in order to comply with the explosion-proof specification, not only the vacuum pump but also the auxiliary pump needs to be an explosion-proof product. Costs. That is, according to this embodiment , it is possible to cope with the explosion-proof specification more easily and at a lower cost than the prior art.

Next, a reference example of the present invention will be described with reference to FIG.

As shown in FIG. 3, the vacuum device 100 of this reference example excludes the check valve 24 and the bypass pipe 28 (excluding the ejector 26) from the configuration of the vacuum device 10 of the above-described embodiment , and attaches the ejector 26. The position has been changed. Since the other configuration is the same as that of the above-described embodiment , the same reference numerals as those of the embodiment are given to the same portions, and detailed description thereof is omitted.

In this reference example , the ejector 26 is provided between the final end 16 b of the rotor 16 of the vacuum pump 12 and the middle of the main exhaust pipe 22. Specifically, one end of the suction side pipe 102 is coupled to the suction port 26 a of the ejector 26, and the other end of the suction side pipe 102 is inserted into the final end 16 b of the rotor 16. One end of the discharge side pipe 104 is coupled to the discharge port 26 b of the ejector 26, and the other end of the discharge side pipe 104 is coupled to an arbitrary position in the middle of the main exhaust pipe 22. The supply port 26 of the ejector 26 is coupled to a nitrogen gas pipe (not shown) as in the above-described embodiment .

The vacuum device 100 of the reference example configured as described above operates as follows.

  That is, it is assumed that the dry pump 12 is activated and the drive gas is supplied to the ejector 26. Then, the rotor 16 of the dry pump 12 rotates and gas is sucked from the vacuum chamber through the intake port 18. The sucked gas is transferred from the leading end 16a of the rotor 16 toward the final end 16b in the same manner as described above, and is compressed to atmospheric pressure at the final end 16b. The compressed gas is discharged to the main exhaust pipe 22 via the exhaust port 20. The discharged gas, that is, exhaust gas, is sent to the abatement apparatus through the main exhaust pipe 22 as shown by a dotted arrow 150 in FIG.

  On the other hand, the ejector 26 sucks the exhaust gas from the final end 16b of the rotor 16 as shown by a one-dot chain line arrow 152 in FIG. Then, the sucked exhaust gas is discharged from the discharge port 26b together with the driving gas supplied to itself. The discharged discharge gas is joined to the main exhaust pipe 22 through the discharge side pipe 104 as shown by a two-dot chain line arrow 154 in FIG. The discharge gas joined to the main exhaust pipe 22 is sent to the abatement apparatus together with the exhaust gas flowing through the main exhaust pipe 22.

Here, a pressure gradient is formed in the rotor 16 from the leading end 16a toward the final end 16b, and in the vicinity of the final end 16b, the pressure is substantially equal to the (naturally) atmospheric pressure. However, in this reference example , the final end 16 b is exhausted by the ejector 26. Therefore, the final end 16b is depressurized, for example, a vacuum of about 8 × 10 ³ [Pa]. And since the final end 16b is evacuated in this way, the pressure difference between the final end 16b and the leading end 16a is reduced. As a result, the load applied to the rotor 16 is reduced, and as a result, the dry pump 12 Drive power is reduced.

Further, the discharge gas discharged from the ejector 26 is merged with the exhaust gas flowing through the main exhaust pipe 22 as described above, and this discharge gas contains nitrogen gas as a driving gas. Therefore, as in the above-described embodiment , a gas purge process is inevitably performed with the nitrogen gas.

Thus, also with the vacuum apparatus 100 of this reference example , the drive power of the dry pump 12 is reduced by adding the ejector 26 as an auxiliary pump. Since the ejector 26 as the auxiliary pump has durability and reliability that cannot be compared with the mechanical pump, the auxiliary pump is compared with the above-described conventional technology that employs the mechanical pump as the auxiliary pump. The running cost including the maintenance cost can be greatly reduced. In addition, the gas purge process can be performed simultaneously with the exhaust process. This is extremely effective for exhausting corrosive gas, flammable gas, harmful gas and the like.

In this reference example , the final end 16b of the rotor 16 is exhausted by the ejector 26. However, the present invention is not limited to this. That is, even if it is not the final end 16b, the vicinity of the final end 16b, for example, the interdental space (space) 16c in front of the final end 16b is in a pressure state substantially equal to the atmospheric pressure. In addition, the previous interdental space 16 c may be exhausted by the ejector 26.

In this reference example , similarly to the above-described embodiment , for example, instead of nitrogen gas, other inert gas such as argon gas or helium gas may be employed as the driving gas, or compressed air may be used. You may employ | adopt as drive gas. Further, in place of the screw-type dry pump 12, other volume transfer type pumps such as a multistage roots pump and a multistage claw pump may be employed. Further, by adopting an explosion-proof product as the vacuum pump 12, the entire vacuum device 100 may be made explosion-proof. And of course, the vacuum apparatus 100 of this reference example can also be applied to the use which does not require a gas purge process.

It is a figure which shows schematic structure of one Embodiment of this invention. It is a graph which shows the power characteristic of the embodiment . It is a figure which shows schematic structure of the reference example of this invention.

DESCRIPTION OF SYMBOLS 10 Vacuum apparatus 12 Dry pump 16 Rotor 18 Intake port 20 Exhaust port 22 Main exhaust pipe 24 Check valve 26 Ejector 28 Bypass pipe 30 Suction side branch pipe 32 Discharge side branch pipe

Claims (7)

A mechanical vacuum pump that compresses the gas sucked from the intake port to atmospheric pressure and discharges it from the exhaust port;
An exhaust pipe having one end coupled to the exhaust port and transferring the gas discharged from the exhaust port to the other end;
A check valve provided in the exhaust pipe as a forward direction from the one end to the other end of the exhaust pipe;
An ejector as an auxiliary pump that is coupled to the upstream side of the check valve of the exhaust pipe and sucks the gas from the upstream side by supplying driving gas and discharges the gas together with the driving gas;
A merging pipe for joining the discharge gas discharged from the ejector to the downstream side of the check valve of the exhaust pipe;
Comprising
A purge gas for performing a gas purge process on the gas is used as the driving gas.
Vacuum device. The vacuum apparatus according to claim 1 , wherein the ejector has a smaller exhaust capacity than the vacuum pump. The vacuum pump is a screw-type dry pump, a vacuum apparatus according to claim 1 or 2. The vacuum apparatus according to claim 1, wherein the gas includes a gas that requires the gas purge process. The vacuum apparatus according to claim 1, wherein the driving gas is nitrogen gas. The vacuum apparatus according to claim 1, wherein the driving gas is compressed air. The vacuum apparatus according to claim 1, wherein the vacuum pump is an explosion-proof product.

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