Patent Grant
11466701
This application is a Section 371 National Stage Application of International Application No. PCT/JP2018/047673, filed Dec. 25, 2018, which is incorporated by reference in its entirety and published as WO 2019/131682 A1 on Jul. 4, 2019 and which claims priority of Japanese Application No. 2017-250428, filed Dec. 27, 2017 and Japanese Application No. 2018-238342, filed Dec. 20, 2018.
The present invention relates to a vacuum pump used as gas exhaust means for a process chamber of a semiconductor manufacturing process apparatus, a flat panel display manufacturing apparatus, a solar panel manufacturing apparatus, and other vacuum process chambers, as well as a stator component, a discharge port, and control means used in the vacuum pump and, more particularly, to such means suited for removal of a product deposited in a flow path in a pump.
in a semiconductor manufacturing process apparatus, a sublimation gas such as TiF4 or AlCl3 may be generated as reaction by-products during a process thereof. When such a sublimation gas is sucked by a vacuum pump and the sucked gas flows through a flow path in the vacuum pump, the sublimation gas is solidified and deposited on an inner wall surface of the flow path at a point at which the relationship between the pressure (partial pressure) and the temperature of the gas in the flow path, which is represented by a vapor pressure curve, shifts from a gaseous phase to a solid phase. Significant deposition occurs particularly at a point where the pressure is relatively high, such as vicinity of a downstream portion of the flow path.
In order to remove the product deposited as described above, heating and thermally insulating means such as a band heater is conventionally used to heat and thermally insulate a vacuum pump (see, for example, Japanese Patent Application Publication No. 2015-31153 or Japanese Patent Application Publication No. 2015-148151).
However, in a conventional method that heats and thermally insulates a vacuum pump as described above, structural components of the vacuum pump such as a rotating body are also heated and kept warm. Since particularly a rotating body of a vacuum pump rotates at high speed, if the rotating body continues to rotate with the designed allowable temperature of the material of the rotating body exceeded by heating and thermal insulation, the rotating body is broken by reduction in the strength of the material thereof, the rotating body is deformed by the creep strain of the rotating body, the deformed rotating body makes contact with a stator component located on the outer periphery thereof, and the rotating body and the stator component are broken due to the contact. Accordingly, the conventional method that heats and thermally insulates a vacuum pump is not suited for the removal of the product deposited in the flow path of the vacuum pump.
In addition, a gas with difficulty in removal of a deposited product, such as a gas with a high sublimation temperature, may flow through the flow path in the vacuum pump. In this case, since the product continues to be deposited in the gas flow path formed between the rotating body of the vacuum pump and a stator component located on the outer periphery thereof, the rotating body makes contact with the stator component via the deposited product, thereby breaking the rotating body or the stator component.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background.
The present invention addresses the above problems with an object of providing a vacuum pump suited for removal of a product deposited in a flow path in the vacuum pump, as well as a stator component, a discharge port, and control means that are used in the vacuum pump.
To achieve the object, the present invention includes a rotating body disposed in a casing; supporting means rotatably supporting the rotating body; driving means configured to rotationally drive the rotating body; an inlet port configured to suck a gas by rotation of the rotating body; an outlet port configured to exhaust the gas sucked through the inlet port; a flow path through which the gas is transferred from the inlet port toward the outlet port; and removing means configured to remove a product deposited on an inner wall surface of the flow path, in which the removing means has an injection hole with one end opened at the inner wall surface of the flow path and a removing gas is injected into the flow path through the injection hole.
The present invention may further include control means configured to function as means for performing control of any of a pressure, a flowrate, or an injection time of the removing gas.
In the present invention, detection means that detects a supply situation by a gas supply system that supplies the removing gas to the injection hole may be provided at a midpoint of the gas supply system.
In the present invention, the control means may function as means for outputting a signal required to adjust a supply pressure or a supply flowrate of the removing gas with respect to the injection hole based on a detection result by the detection means.
In the present invention, the control means may function as means for estimating a deposition amount of a product based on a detection result by the detection means and, when the estimated deposition amount exceeds a threshold, outputting a signal required to adjust a supply pressure or a supply flowrate of the removing gas with respect to the injection hole or outputting a signal required to sound an alert.
In the present invention, the control means may function as means for supplying the removing gas to the injection hole based on an instruction from an external device.
In the present invention, the control of the injection time may include at least either one of control that constantly injects the removing gas through the injection hole and control that intermittently injects the removing gas through the injection hole.
In the present invention, the control of the flowrate may include at least either one of control that keeps the flowrate of the removing gas injected through the injection hole constant and control that increases or reduces the flowrate.
In the present invention, the control of the pressure may include at least either one of control that keeps the pressure of the removing gas injected through the injection hole constant and control that supplies, to the injection hole in a projecting manner, the removing gas injected through the injection hole.
In the present invention, the removing gas may be an inert gas.
In the present invention, the removing gas may be a high-energy gas activated by exciting means.
In the present invention, the removing gas may be a high-temperature gas heated by heating means.
In the present invention, a plurality of injection holes, each of the plurality of injection holes being the injection hole, may be provided.
In the present invention, the inner wall surface of the flow path may be made of a porous material and holes of the porous material may be adopted as the injection hole.
In the present invention, by masking a part of a surface of the porous material constituting the inner wall surface of the flow path and configuring a portion other than the part of the surface as a non-masked portion that is not masked, the removing gas may be injectable into the flow path through the holes of the porous material within a range of the non-masked portion.
In the present invention, a plate body having a surface area larger than an opening area of an opening end of the injection hole may be provided near the opening end and the plate body may be made of a porous material and holes of the porous material may be adopted as the injection hole.
In the present invention, the flow path may be shaped like a thread groove formed between an outer periphery of the rotating body and a stator member opposed to the outer periphery and the flow path and one end of the injection hole may be opened in a portion of the inner wall surface of the flow path close to a downstream exit of the flow path.
In the present invention, the flow path may be shaped like a thread groove formed between an outer periphery of the rotating body and a stator member facing the outer periphery and the flow path and one end of the injection hole may be opened in a portion of the inner wall surface of the flow path close to an upstream entrance of the flow path.
in the present invention, the flow path may include a clearance set between a rotor blade provided on an outer peripheral surface of the rotating body and a stator blade positioned and fixed in the casing and one end of the injection hole may be opened in the portion of the inner wall surface of the flow path close to a downstream exit of the flow path.
In the present invention, the flow path may include a discharge port communicating with a downstream exit of the flow path and one end of the injection hole may be opened at the inner wall surface of the discharge port.
In the present invention, the flow path may include a clearance set between a rotor blade provided on an outer peripheral surface of the rotating body and a stator blade positioned and fixed in the casing, and the flow path may include an inner surface of a spacer that positions and fixes the stator blade and one end of the injection hole may be opened in an inner wall surface of the spacer.
In the present invention, the flow path may include a clearance set between a rotor blade provided on an outer peripheral surface of the rotating body and a stator blade positioned and fixed in the casing and one end of the injection hole may be opened in an outer surface of the stator blade.
In the present invention, the supply based on the instruction may include processing that outputs a maintenance request signal to the external device and processing that outputs a signal required for the supply of the removing gas to the injection hole when a maintenance permission signal output from the external device in response to the maintenance request signal is received.
In the present invention, the inner wall surface of the flow path may be coated with a material having higher non-adhesiveness or lower surface free energy than a structural base material of the flow path.
In the present invention, the material with which the inner wall surface of the flow path is coated may be fluororesin or a coating material including fluororesin.
The present invention is a stator component included in a flow path of a vacuum pump, the stator component including a rotating body disposed in a casing; supporting means rotatably supporting the rotating body; driving means configured to rotationally drive the rotating body; an inlet port configured to suck a gas by rotation of the rotating body; art outlet port configured to exhaust the gas sucked through the inlet port; and a flow path through which the gas is transferred from the inlet port toward the outlet port, in which an injection hole with one end opened in art inner wall surface of the stator component is provided as removing means for removing a product deposited on an inner wall surface of the flow path.
The present invention is an discharge port included in the outlet port of a vacuum pump, the outlet port including a rotating body disposed in a casing; supporting means rotatably supporting the rotating body; driving means configured to rotationally drive the rotating body; an inlet port configured to suck a gas by rotation of the rotating body; an outlet port configured to exhaust the gas sucked through the inlet port; and a flow path through which the gas is transferred from the inlet port toward the outlet port, in which an injection hole with one end opened in art inner wall surface of the stator component is provided as removing means for removing a product deposited on an inner wall surface of the discharge port.
The present invention is control means of a vacuum pump, the control means including a rotating body disposed in a casing; supporting means rotatably supporting the rotating body; driving means configured to rotationally drive the rotating body; an inlet port configured to suck a gas by rotation of the rotating body; an outlet port configured to exhaust the gas sucked through the inlet port; a flow path through which the gas is transferred from the inlet port toward the outlet port; and removing means configured to remove a product deposited on an inner wall surface of the flow path, the removing means having an injection hole with one end opened at the inner wall surface of the flow path and injecting a removing gas into the flow path through the injection hole, in which the control means controls one of a pressure, a flowrate, and an injection time of the removing gas injected into the flow path through the injection hole is controlled, outputs a signal required to adjust a supply pressure or a supply flowrate of the removing gas, functions as means for outputting a signal required to sound an alert, or functions as means for supplying the removing gas to the injection hole based on an instruction from an external device.
in the present invention, as a specific structure of the removing means for removing the product on the inner wall surface of the flow path, the removing means adopts a structure that has an injection hole with one end opened at the inner wall surface of the flow path and injects the removing gas into the flow path through the injection hole, as described above. Accordingly, the product deposited on the inner wall surface of the flow path is forcibly peeled off and removed by a physical force of the removing gas injected through the injection hole, not by heating and thermally insulating the pump as conventional. Therefore, conventional failures due to heating and thermal insulation of the pump (such as, breakage due to reduction in the material strength of the rotating body, deformation due to creep strain of the rotating body, contact between the deformed rotating body and the stator component located on the outer periphery thereof, or breakage of the rotating body or the stator component due to the contact) do not occur, so it is possible to provide a vacuum pump suited for removal of the product deposited in the flow path of the vacuum pump, as well as a stator component, an discharge port, and control means used in the vacuum pump.
In the present invention, “holes of a porous material are adopted as injection holes” includes “a part of the holes of a porous material is adopted as injection holes” and “all of the holes of a porous material are adopted as an injection hole”. This is also true of DESCRIPTION OF THE PREFERRED EMBODIMENTS.
In the present invention, “a removing gas can be into the flow path through holes of a porous material” includes “a removing gas can be injected into the flow path through a part of the holes of a porous material” and “a removing gas can be injected into the flow path through all of the holes of a porous material”. This is also true of DESCRIPTION OF THE PREFERRED EMBODIMENTS.
The Summary is provided to introduce a selection of concepts in a simplified form that are further described in the Detail Description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
A preferred embodiment of the present invention will be described in detail below with reference to the attached drawings.
Referring to
The casing 1 has a bottomed cylindrical shape formed by integrally joining a cylindrical pump case 1A to a bottomed cylindrical pump base 1B in a cylinder axis direction thereof with a tightening bolt and an upper end portion of the pump case 1A is opened as the inlet port 2.
in addition, an discharge port EX is provided in a side surface of a lower end portion of the pump base 1B and one end of the discharge port EX communicates with the flow path R and another end of the discharge port EX is opened as the outlet port 3.
Referring to
As illustrated in
[The rotating body RT described above is provided outside the stator column 4. The rotating body RT is contained in the pump case 1A and the pump base 1B and has a cylindrical shape surrounding the outer periphery of the stator column 4.
A rotating shaft 5 is provided inside the stator column 4. The rotating shaft 5 is disposed so that an upper end portion thereof faces the inlet port 2 and a lower end portion thereof faces the pump base 1B. In addition, the rotating shaft 5 is rotatably supported by magnetic bearings (specifically, two sets of known radial magnetic bearings MB1 and one set of known axial magnetic bearings MB2). In addition, a driving motor MO is provided inside the stator column 4 and the rotating shaft 5 is rotationally driven about the shaft center by this driving motor MO.
The upper end portion of the rotating shaft 5 projects upward from the upper end surface of the cylinder of the stator column 4 and the upper end side of the rotating body RT is integrally fixed to the projecting upper end portion of the rotating shaft 5 by fastening means such as a bolt. That is, the rotating body RT is rotatably supported by the magnetic bearings (radial magnetic bearings MB1 and axial magnetic bearings MB2) via the rotating shaft 5 and, when the driving motor MO is started in this support state, the rotating body RT can rotate about the shaft center thereof integrally with the rotating shaft 5. That is, in the vacuum pump P1 in
In addition, the vacuum pump P1 in
In addition, in the vacuum pump P1 in
Details of the Blade Exhaust Stages PT
A portion of the vacuum pump P1 in
A plurality of rotor blades 6 that rotate together with the rotating body RT are provided on an outer peripheral surface of the rotating body RT upstream of substantially the middle of the rotating body RT and these rotor blades 6 are disposed radially at predetermined intervals about the rotating center axis (specifically, the shaft center of the rotating shaft 5) of the rotating body RT or the shaft center (referred to below as the vacuum pump shaft center) of the casing 1 for each of the blade exhaust stages PT (PT1, PT2, . . . PTn).
On the other hand, a plurality of stator blades 7 are positioned and fixed in the casing 1 (specifically, the inner peripheral side of the pump case 1A) and these stator blades 7 are also disposed radially at predetermined intervals about the vacuum pump shaft center for each of the blade exhaust stages PT (PT1, PT2, . . . PTn) as the rotor blades 6.
That is, the blade exhaust stages PT (PT1, PT2, . . . PTn) are provided in multiple stages between the inlet port 2 and the outlet port 3, and the plurality of rotor blades 6 and the plurality of stator blades 7 radially disposed at predetermined intervals are provided for each of the blade exhaust stages PT (PT1, PT2, . . . PTn) and gas molecules are exhausted by the rotor blades 6 and the stator blades 7.
Any of the rotor blades 6 is a blade-shaped cut product formed by cutting integrally with the outer diameter machined portion of the rotating body RT and inclined at an angle appropriate for exhausting gas molecules. Any of the stator blades 7 is also inclined at an angle appropriate for exhausting gas molecules.
In addition, although the vacuum pump P1 in
Description of Exhaust Operation in the Plurality of Blade Exhaust Stages PT
In the highest blade exhaust stage PT (PT1) of the plurality of blade exhaust stages PT having the above structure, the plurality of rotor blades 6 rotate at high speed integrally with the rotating shaft 5 and the rotating body RT when the driving motor MO is started, and gas molecules input through the inlet port 2 are given kinetic momentum in the downward direction and the tangential direction by inclined planes of the rotor blades 6 on the front surface in the rotational direction and the downward direction (direction from the inlet port 2 to the outlet port 3, which abbreviated below as the downward direction). Such gas molecules having the kinetic momentum in the downward direction are sent to the next blade exhaust stage PT (PT2) by a downward inclined planes, provided on the stator blades 7, that have a rotational direction opposite to that of the rotor blades 6.
Also in the next blade exhaust stage PT (PT2) and subsequent blade exhaust stages PT, the rotor blades 6 rotate and the rotor blades 6 give kinetic momentum to gas molecules and the stator blades 7 send gas molecules as in the highest blade exhaust stage PT (PT1), so gas molecules near the inlet port 2 are transferred sequentially toward the downstream side of the rotating body RT and exhausted.
As is clear from exhaust operation of gas molecules in the plurality of blade exhaust stages PT described above, in the plurality of blade exhaust stages PT, the clearances set between the rotor blades 6 and the stator blades 7 are flow paths (referred to below as inter-blade exhaust flow paths R1) through which the gas is exhausted. This inter-blade exhaust flow paths R1 include, as an inner wall surface structure thereof, outer surfaces of the rotor blades 6 and the stator blades 7, and inner surfaces (surfaces opposed to the outer periphery of the rotating body RT) of the spacers S that position and fix the stator blades 7.
Details on the Thread Groove Pump Stage PS
A portion of the vacuum pump P1 in
The thread groove pump stage PS has the thread groove exhaust portion stator 8 as means for forming a thread groove exhaust flow path R2 on the outer peripheral side (specifically, the outer peripheral side of the rotating body RT downstream of substantially the middle of the rotating body RT) of the rotating body RT and this thread groove exhaust portion stator 8 is attached to the inner peripheral side of the casing 1 as the stator component of the vacuum pump.
The thread groove exhaust portion stator 8 is a cylindrical stator member with an inner peripheral surface disposed so as to be opposed to the outer peripheral surface of the rotating body RT and disposed so as to surround the portion of the rotating body RT downstream of substantially the middle of the rotating body RT.
In addition, the portion of the rotating body RT downstream of substantially the middle of the rotating body RT rotates as a rotating component of a thread groove pump stage PS and is inserted and housed inside the thread groove exhaust portion stator 8 via a predetermined gap.
A thread groove 81 having a depth that changes like a tapered cone whose diameter is reduced toward a lower portion is formed in the inner peripheral portion of the thread groove exhaust portion stator 8. This thread groove 81 is carved spirally from the upper end to the lower end of the thread groove exhaust portion stator 8.
The thread groove exhaust portion stator 8 having the thread groove 81 described above forms the thread groove exhaust flow path R2 through which the gas is exhausted, on the outer peripheral side of the rotating body RT. Although not illustrated, the thread groove exhaust flow path R2 described above may be provided by forming the thread groove 81 described above in the outer peripheral surface of the rotating body RT.
Since the gas is transferred while being compressed by drag effects of the thread groove 81 and the outer peripheral surface of the rotating body RT in the thread groove pump stage PS, the depth of the thread groove 81 is deepest in the upstream entrance side (flow path opening end closer to the inlet port 2) of the thread groove exhaust flow path R2 and shallowest in the downstream exit side (flow path opening end closer to the outlet port 3).
The entrance (upstream opening end) of the thread groove exhaust flow path R2 is opened toward the exit, which is specifically a clearance (referred to below as a final clearance GE) between the stator blades 7E constituting the lowest blade exhaust stage PTn and the thread groove exhaust portion stator 8, of the inter-blade exhaust flow path R1 described above, and the exit (downstream opening end) of the thread groove exhaust flow path R2 communicates with the outlet port 3 through an in-pump outlet port side flow path R3.
The in-pump outlet port side flow path R3 communicates with the outlet port 3 from the exit of the thread groove exhaust flow path R2 by providing a predetermined clearance (clearance around the outer periphery of the lower portion of the stator column 4 in the vacuum pump P1 in
Description of Exhaust Operation in the Thread Groove Pump Stage PS
The gas molecules that have reached the final clearance GE (exit of the inter-blade exhaust flow path R1) via transfer by exhaust operation at the plurality of blade exhaust stages PT are transferred to the thread groove exhaust flow path R2. The transferred gas molecules are transferred toward the in-pump outlet port side flow path R3 while being compressed from a transition flow to a viscous flow by drag effects caused by the rotation of the rotating body RT. Then, the gas molecules having reached the in-pump outlet port side flow path R3 flows into the outlet port 3 and is exhausted outside the casing 1 through an auxiliary pump (not illustrated).
Description of the Gas Flow Path R
As is clear from the description above, the vacuum pump P1 in
In the vacuum pump P1 in
Accordingly, even when a product is deposited on the inner wall surface of the flow path R, the deposited product is removed relatively easily. It should be noted here that the coating material may be fluororesin or a material including fluororesin, but the coating material is not limited to these materials.
Description of the Removing Means RM
In the vacuum pump P1 in
In the vacuum pump P1 in
Since the pressure is relatively high and the state of the gas flowing shifts from a gaseous phase to a solid phase near the downstream exit of the thread groove exhaust flow path R2, a product is likely to be deposited. However, the deposited product is forcibly peeled off and removed by a physical force of the removing gas injected through the first injection hole 91.
In the vacuum pump P1 in
The upstream entrance of the thread groove exhaust flow path R2 is opened to the final clearance GE as described above, this final clearance GE intersects with the inter-blade exhaust flow path R1, and a flow of gas molecules to be exhausted significantly changes near the final clearance GE and the upstream entrance of the thread groove exhaust flow path R2. Accordingly, it is found from the experimental results by the inventors et al. that a region (referred to below as an exhaust gas stagnation region) in which the flowrate of the gas to be exhaust is reduced is easily generated and a product is easily deposited in such an exhaust gas stagnation region.
The product deposited in the exhaust gas stagnation region described above is forcibly peeled off and removed by a physical force of the removing gas injected through the second injection hole 92.
The flow path R in the vacuum pump P1 in
Since the discharge port EX is located downstream of the vicinity of the downstream exit of the thread groove exhaust flow path R2, the pressure is higher and a product is deposited easily. However, the deposited product is forcibly peeled off and removed by a physical force of the removing gas injected through the third injection hole 93.
In Structure Example 4 in
In Structure Example 5 in
Although gas introduction ports for the removing gas supply paths 11D and 11E are provided in
Any of the first to fifth injection holes 91, 92, 93, 94, and 95 may be formed by machine work such as boring with a drill or grooving with an end mill when a component (specifically, the thread groove exhaust portion stator 8, the ring material on the outer peripheral surface of the discharge port EX, the spacer S, or the stator blade 7) having these holes is made of a mechanically-machinable material such as a solid material or a cast material.
The plurality of first and second injection holes 91 and 92 and the plurality of fourth and fifth injection holes may be provided along the circumferential direction of the rotating body RT and the plurality of third injection holes 93 may be provided along the circumferential direction of the discharge port EX. In these cases, it is possible to appropriately changes the positions of the injection holes 91, 92, and 93 as needed by disposing these holes at regular intervals or concentrating these holes at positions at which products are easily disposed particularly.
The vacuum pump P1 in
[In addition, the vacuum pump P1 in
Although the vacuum pump P1 in
In addition, the vacuum pump in
The first injection hole 91 may be formed so as to intersect with the flow path R a right angle as illustrated in
In addition, when the plurality of first injection holes 91 are provided as described above, the injection holes 91 may be disposed in a matrix in a circular region as illustrated in
Overview of a Specific Structure of Injection Holes (Porous Material Type)
Since the above-mentioned components (specifically, the thread groove exhaust portion stator 8, the ring member of the outer peripheral surface of the discharge port EX, the spacer S, the stator blades 7, and the like) that form the inner wall surface of the flow path are generally made of a solid material or a cast material, the inner wall surface of the flow path is made of the same material (that is, a solid material or a cast material). However, in Specific Structure (Porous Material Type) Example 1 of Injection Holes, the inner wall surface of the flow path is made of a porous material and holes of the porous material are adopted as the injection holes.
Although the porous material that forms the inner wall surface of the flow path may be a metal material such as, for example, aluminum, stainless steel, or iron or may be a non-metal material such as ceramic or resin (plastic), the porous material is not limited to these materials.
Although the porous material may be formed by sintering and shaping metal powders (powder metallurgy), solidifying powders with a binding material (press forming), crashing a heated material at high speed into the surface of a base material to be made porous to form a porous film (thermal spraying), or using a three-dimensional printer, the porous material may be formed by another method.
In the structure (porous type) example 1 in
In addition, in this structure (porous type) example 1 in
When a part of the discharge port EX is formed by the porous portion PP as described above, the plurality of porous portions PP may be disposed at a predetermined pitch in the circumferential direction of the discharge port EX, as illustrated in, for example,
In addition, a cylindrical porous cylinder EX1 made of a porous material may be inserted into the inside of the discharge port EX as illustrated in, for example,
In this structure (porous material type) example 1 in
Although the whole thread groove exhaust portion stator 8 is formed by a porous material in the porous masking structure described above, only the portion of the whole thread groove exhaust portion stator 8 that constitutes the inner wall surface of the thread groove exhaust flow path R2 may be formed by a porous material.
In addition, in the structure (porous material type) example 1 in
By the way, it is difficult to form an injection hole in the wall surface or the corner portion of the thread groove 81 by machine work such as boring with a drill or grooving with an end mill. In contrast, it is relatively easy to mask a section other than the wall surface or the corner portion described above using the masking member U1 because machine work is not necessary. Accordingly, the structure (referred to below as the non-masked portion injection structure) in which the removing gas can be injected into the flow path through holes of a porous material within the range of the non-masked portion U2 as described above is advantageous because of applicability to a narrow space in which machine work is difficult.
The porous masking structure and the non-masked portion injection structure described above are applicable to not only the first injection hole 91, but also the second and third injection holes 92 and 93 and the fourth and fifth injection holes 94 and 95.
Specifically, in the example in
The whole stator blade 7 can be made of a porous material and the masking described above can be omitted as illustrated in
In the structure (porous material type) example 3 in
The porous plate injection structure described above is applicable to not only the first injection hole 91, but also the second and third injection holes 92 and 93 and the fourth and fifth injection holes.
Description of a Gas Injected Through Injection Holes
In the vacuum pump P1 in
An example of an inert gas is a nitrogen gas or a noble gas (such as an argon gas, a krypton gas, or a xenon gas) and these poorly-reactive gases are preferably used when an injected gas reacts with a process gas to possibly cause an explosion or generate toxins. It should be noted here that use of a gas with a large molecular weight increases the kinetic energy of the injected gas and thereby improves removal effects.
Since a high-energy gas or a high-temperature gas has an energy density larger than a gas at normal temperature, such a gas has a larger effect of removing a product deposited on the inner surface of the flow path R through injection from the gas injection holes 91, 92, and 93.
Description of the Control Means CX
The vacuum pump P1 in
As a specific structure example of this type of the control means CX, the control means CX is configured by an arithmetic processing apparatus including hardware resources such as, for example, a CPU, a ROM, a RAM, and an input-output (I/O) interface in the vacuum pump P1 in
The control means CX functions as means for performing centralized control of the whole vacuum pump P as described above and also functions as means for supplying a gas to the injection holes 91, 92, and 93 based on an instruction (specifically, the maintenance permission signal) from the external device M.
In this case, the external device M may output the instruction (specifically, the maintenance permission signal) at regular intervals. In addition, to prevent effects on operation of the external device M, the instruction from the external device M is preferably output at a timing at which the degree of vacuum of the external device M is not affected, such as in a period between processes executed by the external device M, a workpiece exchange period, or a maintenance period of the vacuum pump P1, as illustrated in
The instruction (specifically, the maintenance permission signal) may include information about a gas to be injected, such as the type and the control method of a gas to be injected through the injection holes 91, 92, and 93.
The execution by the control means CX may include processing that outputs a maintenance request signal RQ to the external device M and processing that outputs a signal required to supply a gas to the injection holes 91, 92, and 93 when receiving an instruction (specifically, a maintenance permission signal EN) output from the external device M in response to the maintenance request signal RQ, as illustrated in
The maintenance request signal RQ can be output to the external device M via an input-output (I/O) interface of the control means CX and the maintenance permission signal can also be received via the input-output (I/O) interface of the control means CX.
The signal (that is, the signal required to supply a gas to the injection holes 91, 92, and 93) may be output to valves BL1, BL2, BL3, and BL4 described later via an input-output (I/O) interface.
Description of a Gas Injection Control Method by the Control Means CX
The control means CX may function as means for controlling any of the pressure, the flowrate, and the injection time of the removing gas as the injection control method for the removing gas injected through the injection holes 91, 92, and 93.
In addition, the control means CX may function as means for controlling all of the above control targets (the pressure, the flowrate, and the injection time) described above or may function as means for controlling any two (the pressure and the flowrate, the pressure and the injection time, or the flowrate and the injection time) of the control targets.
The control of the injection time by the control means CX may include at least either one of control that constantly injects the removing gas through the injection holes 91, 92, and 93 and control (referred to below as intermittent injection control) that intermittently injects the removing gas through the injection holes 91, 92, and 93.
The control of the flowrate by the control means CX may include at least either one of control that keeps the flowrate of the removing gas injected through the injection holes 91, 92, and 93 constant and control that increases or reduces the flowrate.
The control of the pressure by the control means CX may include at least either one of control that keeps the pressure of the removing gas injected through the injection holes 91, 92, and 93 constant and control (referred to below as a projecting manner gas injection control) that supplies the removing gas injected through the injection holes 91, 92, and 93 to the injection holes in a projecting manner.
The control of the injection time, the flowrate, and the pressure in the control means CX described above can be achieved, as illustrated in, for example,
Regarding the projecting manner gas injection control, the removing gas may be released from the surge tank TK toward the injection holes 91, 92, and 93 at a single burst by providing a surge tank TK capable of temporality reserving the removing gas at a midpoint of a gas supply system SP as illustrated in, for example,
Although the control means CX may adopt a method that makes control so that the injection holes 91, 92, and 93 constantly inject the removing gas, the injection holes 91, 92, and 93 preferably inject the removing gas only when the maintenance request signal is output to the external device M and the instruction (specifically, the maintenance permission signal) from the external device M is received to reduce effects on processes in the external device M as much as possible.
Example in which Detection Means is Simultaneously Used in the Control Means CX
Referring to
When the detection means MM is adopted in the vacuum pump P1 in
First Structure Example and Third Structure Example below may be adopted as a specific structure for achieving the function described above. First Structure Example and Third Structure Example described below may be practiced separately or together.
Estimation Principle of Deposition Amount of a Product
Since the measurement value (pressure) of the detection means MM (pressure gauge) rises and is kept high (see
In addition, since the measurement value (flowrate) of the detection means MM (tlowmeter) is reduced when the clogging occurs, the control means CX can estimate the estimated deposition amount of the product by monitoring changes in the measurement value (flowrate) of the detection means MM.
In addition, as illustrated in
A pressure gauge is adopted as the measuring means MM.
The control means CX adopts processing that receives the measurement value (pressure) by the pressure gauge via the input-output (I/O) interface, processing that determines whether the received measurement value (pressure) exceeds a threshold (for example, an alarm level illustrated in
A flowmeter is adopted as the measuring means MM.
The control means CX adopts processing that receives the measurement value (flowrate) of the flowmeter via the input-output (I/O) interface described above, processing that determines whether the received measurement value (flowrate) is less than a threshold via the CPU, and processing that increases the supply flowrate or the supply pressure of the removing gas with respect to the injection holes 91, 92, and 93 by outputting a predetermined signal to the valve BL2 via the input-output (I/O) interface when this determination processing determines that the received measurement value is less than the threshold.
A pressure gauge is adopted as the measuring means MM.
The control means CX adopts processing that constantly or periodically monitors changes in the measurement value (pressure) of the measuring means MM, processing that estimates a deposition amount of a product based on changes in the measurement value (pressure), and processing that increases the supply amount of the removing gas with respect to the injection holes 91, 92, and 93 by outputting the predetermined signal to the valve BL2 as described in First Structure Example or sounds an alert by outputting a predetermined signal to an alarm device (not illustrated) when the estimated deposition amount of the product exceeds a threshold.
A flowmeter is adopted as the measuring means MM.
The control means CX adopts processing that constantly or periodically monitors changes in the measurement value (flowrate) of the measuring means MM, processing that estimates a deposition amount of a product based on changes in the measurement value (flowrate), and processing that increases the supply flowrate or the supply pressure of the removing gas with respect to the injection holes 91, 92, and 93 by outputting the predetermined signal to the valve BL2 as described in Second Structure Example or sounds an alert by outputting a predetermined signal to an alarm device (not illustrated) when the estimated deposition amount of the product exceeds a threshold.
When the above-mentioned blockage level of the gas supply system SS becomes high, the control means CX may perform control (referred to below as stepwise gas pressure rise control) so as to increase the gas supply pressure of the gas supply system SS in a stepwise manner. In this case, an alarm level that depends on the step may be set and output.
If a deposition (that is, a product deposited in the injection holes 91, 92, and 93 or the gas supply system SS) that causes blockage of the gas supply system SS is removed and the blockage of the gas supply system SS is solved by increasing the gas supply pressure in a stepwise manner as described above, the gas pressure of the gas supply system SS returns to the original pressure. Accordingly, stepwise gas pressure rise control may be cancelled by detecting the original pressure.
When correspondence only by stepwise gas pressure rise control is difficult, the control means CX may make a transition to processing having a larger effect of removing the deposited product (A→B→C) by shifting to processing (A) that switches to the intermittent injection control described above, processing (B) that switches the type of the removing gas to be injected through the injection holes 91, 92, and 93 from, for example, an inert gas at normal temperature to a high-temperature gas, processing (C) that switches the type of the removing gas from a high-temperature gas to a high-energy gas and the like.
When removal of the deposited product by injecting a gas through the injection holes 91, 92, and 93 becomes difficult, the control means CX may prompt the overhaul maintenance or replacement of the vacuum pump by outputting a predetermined signal (HELP signal) to the external device M.
In the vacuum pump P1 according to the embodiment, the removing means RM adopts, as a specific structure of the removing means RM for removing the product deposited on the inner wall surface of the flow path R, the structure in which the removing means RM has the injection hole 91, 92, and 93, 94, or 95 with one ends opened at the inner wall surface of the flow path R and injects the removing gas into the flow path R through the injection hole 91, 92, and 93, 94, or 95. Accordingly, since the product deposited on the inner wall surface of the flow path R is forcibly peeled off and removed by a physical force of the removing gas injected through the injection hole 91, 92, 93, 94, or 95 unlike conventional heating and thermal insulation of a pump, failures (such as, for example, breakage due to reduction in the material strength of the rotating body RT, deformation due to creep strain of the rotating body RT, contact between the deformed rotating body RT and the stator component located on the outer periphery thereof, and breakage of the rotating body RT or the stator component due to the contact) are not caused by conventional heating and thermal insulation of the pump and this structure is suited for removal of the product deposited in the flow path R in the vacuum pump P1.
In addition, since the heating and thermal insulation of the pump can also be used together in the vacuum pump P1 according to the embodiment, the energy required for the heating and thermal insulation of the pump can be reduced.
In addition, if the removing gas is injected through the injection holes 91, 92, and 93 only when the maintenance request signal is output to the external device M and the instruction (specifically, the maintenance permission signal) from the external device M is received in the vacuum pump P1 according to the embodiment, effects of the injection of the removing gas on processes in the external device M can be suppressed and effects on the operation of the external device NI can be prevented.
The present invention is not limited to the embodiment described above and those skilled in the art can make various modifications within the technical spirit of the present invention.
For example, the present invention is also applicable to a structure in which the thread groove pump stage PS is omitted from the vacuum pump P1 illustrated in
Since the thread groove pump stage PS illustrated
In addition, the present invention is also applicable to a drag pump of radial-flow type (such as Siegbahn type) in addition to an axial-flow vacuum pump such as the vacuum pump P1 according to the embodiment described above.
Although elements have been shown or described as separate embodiments above, portions of each embodiment may be combined with all or part of other embodiments described above.
Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are described as example forms of implementing the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2017-250428 | Dec 2017 | JP | national |
| JP2018-238342 | Dec 2018 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2018/047673 | 12/25/2018 | WO |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2019/131682 | 7/4/2019 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6224326 | Puech | May 2001 | B1 |
| 9895727 | Nakamura | Feb 2018 | B2 |
| 20150267296 | Nishida | Sep 2015 | A1 |
| Number | Date | Country |
|---|---|---|
| H01216082 | Aug 1989 | JP |
| 2005325792 | Nov 2005 | JP |
| 2007270742 | Oct 2007 | JP |
| 2015031153 | Feb 2015 | JP |
| 2015148151 | Aug 2015 | JP |
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| Yano et al, machine translation of JP H01 216082, published Aug. 30, 1989 (Year: 1989). |
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| Number | Date | Country | |
|---|---|---|---|
| 20200332811 A1 | Oct 2020 | US |
