JP5121826B2 - Roots type pump and method for manufacturing roots type pump - Google Patents

Description

  The present invention relates to a Roots-type pump that compresses and exhausts gas by transferring gas downstream by a rotor supported by a pair of rotating shafts, and a method for manufacturing the Roots-type pump.

In a semiconductor manufacturing process, an experimental apparatus, an analysis apparatus, or the like that uses a vacuum chamber, a vacuum pump is used for exhausting to a vacuum state. As an example of such a pump, there is known a Roots-type pump that rotates a pair of rotors (rotors) disposed in a casing having a bowl-shaped pump chamber to transfer gas to the downstream side and exhaust the gas. ing.
As the Roots type pump, for example, a technique described in Patent Document 1 (Japanese Patent Laid-Open No. 2003-307192) is known.

  In the Roots type pump (1) described in Patent Document 1 (Japanese Patent Laid-Open No. 2003-307192), the casing (C) includes an upstream end wall (2), a partition wall forming block (B), and a downstream end wall (3). A plurality of pump chambers (P1, P3 to P5) are formed in the partition wall forming block (B), and a bearing (bearing 16) on one end side of the rotating shaft (A1, A2) is formed on the upstream end wall (2). ), And the downstream end wall (3) supports the bearing (bearing 29) on the other end of the rotating shaft (A1, A2). The partition wall forming block (B) is divided into an upper block (B1a, B2a) and a lower block (B1b, B2b).

In the conventional roots type pump as described in Patent Document 1, in order to increase the exhaust performance, the gap between the rotor (R1a, R1b to R5a, R5b) and each pump chamber (P1 to P5) is made small. Therefore, it is necessary to reduce the backflow from the gap. Conventionally, the gap is measured using a gap gauge or the like and adjusted so as to be an appropriate gap. The clearance is adjusted when the pump (1) is assembled.
In the prior art, since the upstream end wall (2) and the downstream end wall (3) are fixed to the upper and lower split wall forming blocks (B), bearings are provided on the upstream end wall (2) and the downstream end wall (3). When adjusting the clearance between the rotors (R1 to R5) on which (16, 29) is supported, first, the partition wall forming block (B) surrounds the rotation shafts (A1, A2) and the rotors (R1 to R5). .

Next, for one end side (for example, the downstream end wall side), the bearing (29) is mounted on the rotation shaft (A1, A2), and the bearing (29) is fixed to the fixed end side wall member (for example, the downstream end wall (3). )) To support.
A rotor (R2a, R2b) disposed at the other end (upstream end wall side) and the pump are used to measure the gap by inserting a gap gauge or the like into the gap between the rotor and the wall of the pump chamber. The shaft (A1, A2) is supported without mounting the bearing (16) or the wall member (upstream end wall (4)) at the other end so that the chamber (P2) is exposed to the outside. Mount the jig.
In this state, the rotary shaft (A1, A2) is moved in the axial direction and finely adjusted to change the gap between the rotor (R2a, R2b) arranged on the other end side and the wall surface of the pump chamber (P2). Is measured with a clearance gauge. At this time, a cumulative value of a gap between each of the plurality of pump chambers (P1 to P5) and each of the rotors (R1 to R5) is measured, and based on the measured value of the gap, the axial direction of the rotary shafts (A1, A2) The position of is fine-tuned.
Then, after fine adjustment of the position in the axial direction, the jig on the free end side is removed, the bearing (16) is mounted, the wall member on the free end side (for example, the upstream end wall (2)) is mounted, The pump is assembled.

JP 2003-307192 A (“0028” to “0035”, “0045”, FIGS. 1 to 4)

In the above-described prior art, since the gap to be measured is detected as a stack of gaps between the pump chambers and the rotor (cumulative value of the gaps), it is unclear which pump chamber has the smallest gap. There is a problem that there is.
In particular, in the roots type pump, it is desirable from the aspect of exhaust performance that the gap is the smallest in the most downstream pump chamber (final pump chamber) where the gas is compressed most. Therefore, in order to minimize the gap in the final stage pump chamber, it is necessary to design the gap between the pump chambers other than the final stage at the design stage, and the exhaust performance on the upstream side deteriorates. There is also.
In addition, since the jig is removed after the gap is adjusted and the bearing is mounted, an error may occur in the adjusted gap.
On the other hand, it is conceivable to directly detect the gap in each pump chamber, but in order to directly detect the gap, it is necessary to form an opening for inserting a gap gauge in each pump chamber. If such an opening is formed, there is a problem that the structure becomes complicated and the cost increases.

  In view of the circumstances described above, a first technical problem of the present invention is to enable a gap between a rotor and a pump chamber to be accurately adjusted with a simple configuration.

In order to solve the technical problem, a roots pump according to claim 1 is provided.
A pair of rotating shafts arranged in parallel;
A rotor provided on each rotating shaft;
A bearing that supports the rotating shaft;
A casing having an intake port for sucking in gas, a pump chamber in which the rotor is accommodated and gas sucked from the intake port is transferred downstream in a gas transfer direction, and an exhaust port for exhausting the transferred gas. The casing having a first casing and a second casing divided along the axial direction of the rotating shaft,
The first casing formed with a first bearing support portion for supporting the bearing and a first rotor housing space in which the rotor is housed;
A second bearing support portion that is formed to face the first bearing support portion and supports the bearing, and is formed corresponding to the first rotor housing space and is surrounded by the first rotor housing space. A second rotor housing space that constitutes the pump chamber by a space that is formed, and the second casing,
The plurality of pump chambers having different volumes, the intake port connected to the pump chamber having the largest volume, the exhaust port connected to the pump chamber having the smallest volume, and the volume in the plurality of pump chambers. And a connection path for connecting gas so as to be sequentially transferred from the large pump chamber to the small pump chamber, where m and n are positive integers, and m ≦ (n / 2 ), The first pump chamber, the second pump chamber,..., The m−1th pump chamber, the mth pump chamber, the m + 1 pump chamber,..., The n−1 pump chamber, the nth. In the case of the pump chamber, the m-th pump chamber, the m-1 pump chamber, the m-2 pump chamber, from the axial one end side to the axial other end side with respect to the axial direction of the rotating shaft, ..., 1st pump chamber, m + 1th pump chamber, m + 2 pump chamber ..., and the casing (n-1) th pump chamber, the first n pump chamber is formed,
It is provided with.

In order to solve the technical problem, the roots pump of the invention according to claim 2,
A pair of rotating shafts arranged in parallel;
A rotor provided on each rotating shaft;
A bearing that supports the rotating shaft;
A casing having an intake port for sucking in gas, a pump chamber in which the rotor is accommodated and gas sucked from the intake port is transferred downstream in a gas transfer direction, and an exhaust port for exhausting the transferred gas. The casing having a first casing and a second casing divided along the axial direction of the rotating shaft,
The first casing formed with a first bearing support portion for supporting the bearing and a first rotor housing space in which the rotor is housed;
A second bearing support portion that is formed to face the first bearing support portion and supports the bearing, and is formed corresponding to the first rotor housing space and is surrounded by the first rotor housing space. A second rotor housing space that constitutes the pump chamber by a space that is formed, and the second casing,
The plurality of pump chambers having different volumes, the intake port connected to the pump chamber having the largest volume, the exhaust port connected to the pump chamber having the smallest volume, and the volume in the plurality of pump chambers. A casing for connecting gas so that gas is sequentially transferred from the large pump chamber to the small volume pump chamber, wherein k and n are positive integers, k <n, In order from the largest pump chamber, the first pump chamber, the second pump chamber, ..., the k-1 pump chamber, the kth pump chamber, the k + 1 pump chamber, ..., the n-1 pump chamber, the nth pump chamber. If, said casing having an intermediate stage exhaust path for exhausting from the k pump chamber and the outlet port and the first k pump chamber by connecting,
It is provided with.

The invention described in claim 3 is the Roots pump according to claim 1 or 2 ,
An airtight member support formed between the bearing and the adjacent pump chamber, which is a pump chamber disposed adjacent to the bearing of the rotating shaft, with respect to the axial direction of the rotating shaft;
A plurality of the airtight members arranged on the airtight member support portion to prevent gas from leaking along the rotation axis, the airtight members being spaced apart along the axial direction. When,
A space connecting path between the airtight members connecting the pump chamber having a smaller volume than the adjacent pump chamber and the space between the airtight members;
It is provided with.

In order to solve the technical problem, the roots pump of the invention according to claim 4,
A pair of rotating shafts arranged in parallel;
A rotor provided on each rotating shaft;
A bearing that supports the rotating shaft;
A casing having an intake port for sucking in gas, a pump chamber in which the rotor is accommodated and gas sucked from the intake port is transferred downstream in a gas transfer direction, and an exhaust port for exhausting the transferred gas. The casing having a first casing and a second casing divided along the axial direction of the rotating shaft,
The first casing formed with a first bearing support portion for supporting the bearing and a first rotor housing space in which the rotor is housed;
A second bearing support portion that is formed to face the first bearing support portion and supports the bearing, and is formed corresponding to the first rotor housing space and is surrounded by the first rotor housing space. A second rotor housing space that constitutes the pump chamber by a space that is formed, and the second casing,
An airtight member support formed between the adjacent pump chamber and the bearing support, which is a pump chamber disposed adjacent to the bearing of the rotary shaft with respect to the axial direction of the rotary shaft;
An airtight member arranged on the airtight member support portion to prevent gas from leaking along the rotation axis;
Lubricant outflow that connects between the lubricant outflow prevention space formed between the airtight member and the bearing, and the atmosphere side space on the opposite side of the lubricant outflow prevention space in the axial direction with respect to the bearing. Prevention connection path,
It is provided with.

In order to solve the technical problem, a roots pump according to claim 5 is provided.
A pair of rotating shafts arranged in parallel;
A rotor provided on each rotating shaft;
A bearing that supports the rotating shaft;
A casing having an intake port for sucking in gas, a pump chamber in which the rotor is accommodated and gas sucked from the intake port is transferred downstream in a gas transfer direction, and an exhaust port for exhausting the transferred gas. The casing having a first casing and a second casing divided along the axial direction of the rotating shaft,
The first casing formed with a first bearing support portion for supporting the bearing and a first rotor housing space in which the rotor is housed;
A second bearing support portion that is formed to face the first bearing support portion and supports the bearing, and is formed corresponding to the first rotor housing space and is surrounded by the first rotor housing space. A second rotor housing space that constitutes the pump chamber by a space that is formed, and the second casing,
A gear chamber that is disposed on one end side of the rotary shaft and that transmits rotation between a pair of rotary shafts; and a gear chamber in which a lubricant for lubricating the gear row is stored;
An intermediate chamber disposed between the gear chamber and the pump chamber along the axial direction of the rotation shaft;
An intermediate chamber connection path connecting the gear chamber and the intermediate chamber;
It is provided with.

The invention according to claim 6 is the Roots type pump according to claim 5 ,
A lubricant removing member that is disposed in the intermediate chamber connection path and removes the gaseous lubricant from the gear chamber to the intermediate chamber;
A flow rate reduction unit that is provided in the intermediate chamber connection path and reduces the flow rate of the moving gas;
It is provided with.

In order to solve the technical problem, a roots type pump according to the invention according to claim 7 is provided.
A pair of rotating shafts arranged in parallel;
A rotor provided on each rotating shaft;
A bearing that supports the rotating shaft;
A casing having an intake port for sucking in gas, a pump chamber in which the rotor is accommodated and gas sucked from the intake port is transferred downstream in a gas transfer direction, and an exhaust port for exhausting the transferred gas. The casing having a first casing and a second casing divided along the axial direction of the rotating shaft,
The first casing formed with a first bearing support portion for supporting the bearing and a first rotor housing space in which the rotor is housed;
A second bearing support portion that is formed to face the first bearing support portion and supports the bearing, and is formed corresponding to the first rotor housing space and is surrounded by the first rotor housing space. A second rotor housing space that constitutes the pump chamber by a space that is formed, and the second casing,
And cooling fins for enlarging the surface area of the heat radiation is provided in the casing,
It is provided with.

The invention according to claim 8 is the Roots pump according to claim 7 ,
A blower blade that is supported by the rotating shaft and blows air to the cooling fins as the rotating shaft rotates.
It is provided with.

In order to solve the technical problem, the roots pump of the invention according to claim 9 is:
A pair of rotating shafts arranged in parallel;
A rotor provided on each rotating shaft;
A bearing that supports the rotating shaft;
A casing having an intake port for sucking in gas, a pump chamber in which the rotor is accommodated and gas sucked from the intake port is transferred downstream in a gas transfer direction, and an exhaust port for exhausting the transferred gas. The casing having a first casing and a second casing divided along the axial direction of the rotating shaft,
The first casing formed with a first bearing support portion for supporting the bearing and a first rotor housing space in which the rotor is housed;
A second bearing support portion that is formed to face the first bearing support portion and supports the bearing, and is formed corresponding to the first rotor housing space and is surrounded by the first rotor housing space. A second rotor housing space that constitutes the pump chamber by a space that is formed, and the second casing,
Disposed in the casing interior in the vicinity of the exhaust port, the muffler for performing mute,
It is provided with.

In order to solve the technical problem, the Roots type pump manufacturing method of the invention according to claim 10 comprises:
A bearing mounting step of mounting a bearing on both ends of each rotating shaft with respect to a pair of rotating shafts provided with a rotor;
A shaft support that supports the bearings of a pair of rotating shafts arranged in parallel in the first casing in which a first bearing support portion that supports the bearings and a first rotor housing space in which the rotor is housed is formed. Process,
A gap adjusting step for adjusting a gap between each rotor of the rotating shaft and a wall surface of the first rotor accommodating space;
The second bearing support portion that is formed to face the first bearing support portion and supports the bearing, is formed corresponding to the first rotor housing space, and is surrounded by the first rotor housing space. The second casing having a second rotor accommodating space that constitutes the pump chamber by a space is mounted on the first casing, and the rotating shaft and the rotor are sandwiched between the first casing and the second casing. A casing assembly process for assembling the casing;
It is characterized by performing.

The invention described in claim 11 is the Roots type pump manufacturing method according to claim 10 ,
A jig mounting step of mounting a phase matching jig, which is supported on the first casing and held in a non-rotatable state in contact with an outer peripheral surface of a rotor provided on one of the rotation shafts, on the first casing; ,
A phase matching step for matching the phases of the rotor provided on one rotating shaft and the rotor provided on the other rotating shaft;
A jig removing step of removing the phase matching jig from the first casing;
Is performed between the shaft support step and the casing assembly step.

According to invention of Claim 1 , 2 , 4 , 5 , 7 , 9 , the casing is divided | segmented into the 1st casing and the 2nd casing, and the bearing of a rotating shaft is provided by the 1st casing or the 2nd casing. Since it can support, a rotating shaft can be supported by one side of a 1st casing or a 2nd casing, and all the rotors supported by the rotating shaft can be hold | maintained in the state open | released outside. Therefore, the gap between the rotor and the rotor accommodating space constituting a part of the pump chamber can be measured for all the rotors. As a result, it is possible to accurately measure and adjust the gap between the rotor and the pump chamber as compared with the conventional technique in which the gap can be measured only between the specific rotor and the pump chamber exposed to the outside. In addition, after the gap adjustment, the other of the first casing and the second casing can be attached to easily assemble with the gap adjusted, and the maintenance can be performed simply by removing the other.

According to the first aspect of the present invention, since the m-th pump chamber having a pressure larger than that of the first pump chamber having the smallest pressure is disposed on the one end side in the axial direction, , The inflow and outflow of gas are reduced, and the ultimate pressure can be improved. Further, even if the member that maintains the airtightness is broken, it is difficult to affect the pressure in the first pump chamber, and the influence on the reduction in the ultimate pressure can be reduced.
According to the second aspect of the present invention, since the volume can be exhausted from the middle k-th pump chamber, the gas is prevented from being over-compressed in the n-th pump chamber where the gas is compressed most. And increase in load torque due to overcompression can be reduced.

According to the third aspect of the present invention, the space between the airtight members is connected to the pump chamber whose volume is smaller than that of the adjacent pump chamber, that is, the pump chamber whose pressure is larger than that of the adjacent pump chamber. Compared with the case where is connected to the atmospheric pressure, the differential pressure between the space between the airtight members and the adjacent pump chamber can be reduced, and the inflow and outflow of gas along the rotation axis can be reduced.
Further , according to the invention described in claim 4 , the lubricant outflow prevention space is connected to the atmosphere side space 52, and both sides in the axial direction of the bearing are at atmospheric pressure. It is possible to prevent the lubricant from leaking out.
Furthermore, according to the fifth aspect of the present invention, since the gear chamber and the intermediate chamber are connected, the differential pressure between the gear chamber and the intermediate chamber is reduced, and the lubricant contained in the gear chamber is transferred to the intermediate chamber. Moving to the pump chamber side from the intermediate chamber can also be reduced.

According to the sixth aspect of the present invention, it is possible to prevent the lubricant that has become gaseous in the gear chamber by the lubricant removing member from moving to the intermediate chamber and to prevent the gaseous lubricant from moving to the pump chamber. it can. In addition, since the flow velocity of the moving gas is reduced by the flow velocity reduction unit, when the pressure of the gear chamber or the intermediate chamber fluctuates, the sudden fluctuation of the pressure of the other chamber is reduced.
According to the seventh aspect of the present invention, the surface area that can be dissipated by the cooling fins increases, so that the casing that generates heat during gas compression can be effectively cooled.
According to the eighth aspect of the present invention, since the air is blown to the cooling fins by the blower blades provided on the rotating shaft, the air can be cooled more effectively.
Furthermore, according to the invention described in claim 9 , since the silencer is built in the casing, the entire Roots pump can be saved.

According to the invention described in claim 10 , in the clearance adjustment step, the first casing supports the rotating shaft, and all the rotors supported by the rotating shaft are open to the outside. Thus, it is possible to measure the gap between the rotor and the rotor accommodating space constituting a part of the pump chamber. Therefore, the gap between the rotor and the pump chamber can be accurately measured and adjusted as compared with the conventional technique in which the gap can be measured only between the specific rotor exposed to the outside and the pump chamber. In addition, after the gap adjustment, the other of the first casing and the second casing can be attached to easily assemble with the gap adjusted, and the maintenance can be performed simply by removing the other.
According to the eleventh aspect of the invention, the phase can be adjusted in a state where the rotating shaft is supported by the first casing and all the rotors are opened to the outside. Compared with the prior art, since the phases of all the rotors can be confirmed, the reliability can be improved.

FIG. 1 is a partial cross-sectional explanatory view of a Roots pump according to a first embodiment of the present invention viewed from the side. FIG. 2 is a partial cross-sectional explanatory view seen from above the roots pump shown in FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is an explanatory view of the grease blow-through preventing structure of the first embodiment, and is an enlarged view of a main part of FIG. FIG. 5 is an explanatory diagram of the vacuum-side seal structure of Example 1, and is an enlarged view of the main part of FIG. 6A and 6B are explanatory diagrams of the isobaric piping structure of the gear chamber according to the first embodiment. FIG. 6A is an enlarged explanatory view of the isobaric piping structure. FIG. It is explanatory drawing. FIG. 7 is an explanatory view of the manufacturing method of the roots pump of the first embodiment, and is an explanatory view showing a state in which the rotating shaft, the lower casing, and the upper casing on which the bearings are mounted are separated. FIG. 8 is an explanatory view of the manufacturing method of the Roots pump according to the first embodiment, and is an explanatory view showing a state in which the rotating shaft on which the bearing is mounted is supported by the lower casing. FIG. 9 is an explanatory view of the manufacturing method of the roots pump of the first embodiment, and is an explanatory view when the rotor is phase-matched from the state shown in FIG. FIG. 10 is an explanatory view of the manufacturing method of the roots pump of the first embodiment, and is an explanatory view showing a state where the upper casing is mounted after the phase alignment shown in FIG. 9 is completed and the jig is removed.

Explanation of symbols

1 ... Roots type pump,
2 ... casing,
3 ... 1st casing,
4 ... second casing,
26 ... Inlet,
27, 28, 29, 30, 31, 32 ... connection path,
34, 36: Intermediate exhaust path,
37 ... exhaust port,
38 ... silencer,
41a, 42a ... cooling fins,
46a, 47a ... 1st bearing support part,
46b, 47b ... second bearing support,
52 ... Atmosphere side space,
53,62 ... Blower blade,
66, 67, 71, 72 ... bearings,
77 ... Gear room,
82, 97 ... airtight member support,
84a, 89 ... Lubricant outflow prevention connection path,
86, 87, 101 ... an airtight member,
88 ... Lubricant outflow prevention space,
91 ... space between airtight members,
92 + 93 ... space connection path between airtight members,
102 ... Intermediate room,
103 + 106 + 107 + 109 ... intermediate chamber connection path,
104 ... Flow velocity reduction part,
108, 111 ... lubricant removing member,
116: phase matching jig,
A1, A2 ... rotating shaft,
G1, G2 ... Gear train,
P1, P2, P3, P4, P5, P6 ... pump chamber,
P1a, P2a, P3a, P4a, P5a, P6a ... first rotor housing space,
P1b, P2b, P3b, P4b, P5b, P6b ... second rotor housing space,
P2 ... Adjacent pump room,
R1a, R1b, R2a, R2b, R3a, R3b, R4a, R4b, R5a, R5b, R6a, R6b... Rotor.

Next, specific examples of embodiments of the present invention (hereinafter referred to as examples) will be described with reference to the drawings, but the present invention is not limited to the following examples.
In order to facilitate understanding of the following description, in the drawings, the front-rear direction is the X-axis direction, the left direction is the Y-axis direction, the up-down direction is the Z-axis direction, and arrows X, -X, Y, -Y, The direction indicated by Z and -Z or the indicated side is defined as the front side, the rear side, the right side, the left side, the upper side, the lower side, or the front side, the rear side, the right side, the left side, the upper side, and the lower side, respectively.
In the figure, “•” in “○” means an arrow heading from the back of the page to the front, and “×” in “○” is the front of the page. It means an arrow pointing from the back to the back.
In the following description using the drawings, illustrations other than members necessary for explanation are omitted as appropriate for easy understanding, and portions necessary for explanation are shown in cross-section as appropriate.

FIG. 1 is a partial cross-sectional explanatory view of a Roots pump according to a first embodiment of the present invention viewed from the side.
FIG. 2 is a partial cross-sectional explanatory view seen from above the roots pump shown in FIG.
3 is a cross-sectional view taken along line III-III in FIG.
1 to 3, the multistage roots pump 1 according to the first embodiment of the present invention has a casing 2. The casing 2 includes a lower lower casing (first casing) 3 and an upper upper casing (second casing) 4, and the casing 2 includes a lower casing 3 and an upper casing 4. It is divided into two along the horizontal plane (along the rotation axis described later) at the center in the vertical direction.

  The casing 2 is formed with a front end wall 13 and a rear end wall 14. Between the front end wall 13 and the rear end wall 14, from the front side (+ X side) to the rear side (−X side). A plurality of partition walls 15, 16, 17, 18, and 19 are formed at predetermined intervals. The front end wall 13, the rear end wall 14, and the first partition wall 15 to the fifth partition wall 19 are connected by an outer wall 21 at the outer peripheral portion. Further, since the casing 2 is divided by the lower casing 3 and the upper casing 4, the front end wall 13, the rear end wall 14, and the first partition wall 15 to the fifth partition wall 19 are respectively the lower front end wall. 13a, lower rear end wall 14a and lower first partition wall 15a to lower fifth partition wall 19a, upper front end wall 13b, upper rear end wall 14b and upper first partition wall 15b to upper fifth partition wall 19b And is constituted by. The outer wall 21 is also composed of a lower outer wall 21a and an upper outer wall 21b.

Between the front end wall 13, the rear end wall 14, and the first partition wall 15 to the fifth partition wall 19, the second pump chamber P2, the first pump chamber P1, and the third pump are sequentially arranged from the front side to the rear side. A chamber P3, a fourth pump chamber P4, a fifth pump chamber P5, and a sixth pump chamber P6 are formed. As shown in FIG. 3, the pump chambers P1 to P6 are all formed in a bowl-shaped cross-sectional shape in which arcs are connected. And since the said pump chambers P1-P6 differ in the width | variety of the front-back direction and the cross-sectional shape is the same, volume (= width x cross-sectional area) changes. In the first embodiment, the volume decreases in the order of the first pump chamber P1 having the largest volume, the second pump chamber P2, the third pump chamber P3, the fourth pump chamber P4, and the fifth pump chamber P5, and the sixth pump chamber. The volume of P6 is set to the minimum.
In Example 1, since casing 2 is divided by lower casing 3 and upper casing 4, each pump room P1-P6 is respectively connected with lower pump room (first rotor accommodation space) P1a-P6a. The upper pump chamber (second rotor housing space) P1b to P6b.

  1 and 3, an intake port 26 is formed above the upper casing 4, and the intake port 26 is connected to the upper end of the first pump chamber P1. In FIG. 3, the first pump chamber P1 has a lower end that is formed in the outer wall 21 and extends upward so as to wrap around the outer periphery of the first pump chamber P1, and is connected to the upper end of the second pump chamber P2. One connection path 27 is formed. Similarly, the second connection path 28 to the fifth connection path 31 (FIG. 2) connecting the downstream ends of the second pump chamber P2 to the fifth pump chamber P5 and the upper ends of the pump chambers P3 to P6 having the next smallest volume. Is formed around the pump chambers P2 to P6.

In FIG. 2, the lower end (downstream end) of the sixth pump chamber P <b> 6 is connected to an exhaust portion 33 formed at the left end portion of the casing 4 by an exhaust connection path 32. In FIG. 3, in the first embodiment, a first intermediate connecting the downstream end of the second pump chamber P2 and the exhaust part 33 is connected to the second connection path 28 connected to the downstream end of the second pump chamber P2. A stage exhaust path 34 is formed. A check valve 34 a for preventing a back flow from the exhaust part 33 to the second pump chamber P <b> 2 is disposed at a connection part of the first intermediate stage exhaust path 34 to the exhaust part 33. In FIG. 2, similarly to the first intermediate stage exhaust path 34, the downstream end of the third pump chamber P <b> 3 and the exhaust part 33 are connected by a second intermediate stage exhaust path 36, and the second intermediate stage exhaust path is connected. A check valve 36 a is also disposed in the path 36.
In FIG. 3, an exhaust port 37 is formed at the upper end of the exhaust unit 33, and a silencer 38 as an example of a silencer is disposed below the exhaust port 37 in order to mute the sound during exhaust. Has been. Therefore, the silencer 38 is built in the casing 2 in the roots type pump 1 of the first embodiment.

1 and 3, the lower surface of the lower casing 3 is closed by a lower lid member 41 for closing the lower ends of the connection paths 27 to 31, and the upper surface of the upper casing 4 is the intake port. 26 and an upper lid member 42 provided with an exhaust port 37. The lower lid member 41 and the upper lid member 42 are provided with plate-like cooling fins 41a and 42a extending in parallel in the front-rear direction. That is, the lower lid member 41 and the upper lid member 42 also have a function as a radiator, a so-called heat sink.
In FIG. 1, a pedestal member (base member) 43 is disposed below the outer wall 21 a of the lower casing 3, and the pedestal member 43 supports the casing 2 by a plurality of columnar legs 44. ing.

  1 and 2, the casing 2 is formed with a concave front bearing support portion 46 on the front side of the front end wall 13, and a concave rear bearing support on the rear side of the rear end wall 14. A portion 47 is formed. Since the casing 2 of Example 1 is divided into the lower casing 3 and the upper casing 4, the bearing support portions 46 and 47 include lower bearing support portions (first bearing support portions) 46 a and 47 a, and It consists of upper bearing support parts (second bearing support parts) 46b and 47b.

In FIG. 2, a motor support cover 51 is fixedly supported on the front end portion of the outer wall 21 of the casing 2. A drive connection chamber (atmosphere side space) 52 is formed in the motor support cover 51. 1 and 2, a blowing fixed blade 53 is fixedly supported at the central portion in the front-rear direction of the motor support cover 51. In FIG. 1, a cooling air inlet 54 is formed at the front lower end of the motor support cover 51, and air outlets 56 are provided at the upper and lower ends of the motor support cover 51 in order to blow air to the cooling fins 41a and 42a. Is formed.
A motor M is fixedly supported at the front end of the motor support cover 51. A motor shaft M 1 extending from the motor M extends through the motor support cover 51 into the drive connection chamber 52. A driving side coupling M1a having a plurality of claws is fixedly supported at the tip of the motor shaft M1.

2 and 3, the Roots pump 1 has a drive shaft (rotary shaft) A1 extending in the front-rear direction. A driven side coupling 61 that meshes with the driving side coupling M1a of the motor shaft M1 is fixedly supported at the front end portion (one end portion) of the driving shaft A1. A key 61a is formed on the driven side coupling 61, and the driven side coupling 61 and the driving shaft A1 are integrated by engaging the key 61a with a key groove A1a formed on the driving shaft A1. Rotate to.
In FIG. 2, a blowing rotor blade 62 facing the blowing fan blade 53 is fixedly supported at the rear end of the driven side coupling 61. The blower blades (53 + 62) of Example 1 are constituted by the blower fixed blades 53 and the blower rotary blades 62, which constitute a so-called centrifugal fan. Therefore, as the drive shaft A1 rotates, the blower rotary blade 62 rotates, and the gas in the drive connection chamber 52 is blown from the blower port 56 to the cooling fins 41a and 42a. In the first embodiment, the casing 2 and the lid members 41 and 42 are made of an aluminum material with good cooling properties, but the material is not limited to the aluminum material, and any material that can be used as the casing 2 or the like. Can be used.

The drive shaft A1 extends rearward through the front end wall 13, the rear end wall 14 and the first partition wall 15 to the fifth partition wall 19 of the casing 2, and has bearings (bearings) 66, 67 at both front and rear ends. Is supported rotatably. The front bearing 66 is supported by the front bearing support portion 46 of the casing 2 via the front bearing mounting member 68, and the rear bearing 67 is supported by the rear bearing of the casing 2 via the rear bearing mounting member 69. Supported by the portion 47.
In the casing 2, a driven shaft (rotating shaft) A2 that is disposed in parallel with the drive shaft A1 and passes through the front end wall 13, the rear end wall 14, and the first partition wall 15 to the fifth partition wall 19 is provided. Is arranged. Both front and rear ends of the driven shaft A2 are rotatably supported by bearings 71 and 72, and the bearings 71 and 72 of the driven shaft A2 are also supported by bearing support portions 46 and 47 via the bearing mounting members 68 and 69. ing.

The drive gear G1 and the driven gear G2 are fixedly supported at the rear end portions (the other end portions) of the drive shaft A1 and the driven shaft A2, respectively, and the drive gear G1 and the driven gear G2 are engaged with each other. Therefore, when the drive shaft A1 rotates by driving the motor M, the rotation is transmitted by the gear trains G1 and G2, and the driven shaft A2 also rotates.
In FIG. 3, a pair of rotors R1, R2, R3, R4, R5, and R6 corresponding to the widths of the pump chambers P1 to P6 are fixedly supported on the drive shaft A1 and the driven shaft A2. That is, the drive shaft A1 supports the drive-side rotors (first rotors) R1a, R2a, R3a, R4a, R5a, R6a, and the driven shaft A2 has the driven-side rotors (second rotors) R1b, R2b, R3b. , R4b, R5b, R6b are supported. In FIG. 3, each of the rotors R1a, R1b to R6a, R6b of the first embodiment is convexly curved and formed along a circular arc, and a convex curved portion 73 that is curved along a circular arc and formed along an envelope curve. The other-side convex curved portion 73 has a concave curved portion 74 that is close, and the entire shape is formed in a bowl shape. The outer peripheral surface of the convex curved portion 73 is close to the inner peripheral surface of the pump chambers P1 to P6, and the rotors R1 to R6 and the inner peripheral surfaces of the pump chambers P1 to P6 are rotated by rotation of the rotors R1 to R6. The gas in the enclosed space is transferred to the downstream side (downward in the first embodiment). And gas is compressed and exhausted because the volume of each pump chamber P1-P6 becomes small sequentially.
In Example 1, the bearing mounting members 68 and 69, the bearings 66, 67, 71 and 72, and the rotors R1 to R6 use cast iron, but the material is not limited to cast iron and can be used. Any material can be used.

  A gear chamber cover 76 is fixedly supported on the rear end wall 14 of the casing 2 so as to surround the gears G 1 and G 2, and a gear chamber 77 is formed inside the gear chamber cover 76. The gear chamber 77 contains lubricating oil as an example of a lubricant for lubricating the gears G1 and G2. In Example 1, the lubricating oil is contained in such an amount that the lower ends of the gears G1 and G2 are immersed. 1 and 2, cooling fins 76 a are formed on the outer peripheral surface of the gear chamber cover 76. In FIG. 2, a lubricant introduction port 76 b is formed in the right portion (+ Y portion) of the gear chamber cover 76, and the lubricant introduction port 76 b is plugged with a sealing plug 78.

(Description of vacuum side grease blow-off prevention structure and vacuum side seal structure)
FIG. 4 is an explanatory view of the grease blow-through preventing structure of the first embodiment, and is an enlarged view of a main part of FIG.
FIG. 5 is an explanatory diagram of the vacuum-side seal structure of Example 1, and is an enlarged view of the main part of FIG.
1, 2, 4, and 5, the front bearing mounting member 68 is formed with a front bearing mounting portion 81 to which the front bearings 66 and 71 are mounted, and the rear side in the axial direction of the front bearing mounting portion 81 ( On the −X side), a front side airtight member support portion 82 is formed. The front bearings 66 and 71 are so-called ball bearings (ball rolling bearings), and outer rings (outer races) 66a and 71a supported by the bearing mounting portion 81 and inner rings (inner rings) that support the rotation shafts A1 and A2. Race) 66b, 71b and balls (rolling elements) 66c, 71c rotating between the outer rings 66a, 71a and the inner rings 66b, 71b. In the first embodiment, grease is used as a lubricant for the front bearings 66 and 71.
4 and 5, the outer rings 66 a and 71 a of the front bearings 66 and 71 are positioned and fixed by a front fixing member 84 fixedly supported on the front end surface of the front bearing mounting member 68 via a wave washer 83. . A connecting passage through hole 84 a is formed at the center of the front fixing member 84.

A pair of front side seal members (airtight members) 86 and 87 are supported by the front side airtight member support portion 82, and the front side seal members 86 and 86 have a two-stage seal structure. The seal members 86 and 87 are disposed in contact with the rotary shafts A1 and A2 whose front end portions rotate, and are connected to the second pump chamber (adjacent pump chamber) P2 along the rotary shafts A1 and A2. Gas is prevented from flowing in (leaking out).
In FIG. 4, a lubricant outflow prevention space 88 is formed between the front bearings 66 and 71 and the front seal members 86 and 87. A lubricant outflow prevention connection path 89 that connects the lubricant outflow prevention space 88 and the drive coupling chamber 52 is formed in the left-right direction (Y-axis direction central portion) of the front bearing mounting member 68. The path through hole 84 a is connected to the drive connection chamber 52 through a lubricant outflow prevention connection path 89.

  In FIG. 5, an airtight member space 91 is formed between the front first seal member 86 and the front second seal member 87 having a two-stage seal structure in the front airtight member support portion 82. . The front bearing mounting member 68 is formed with a mounting member connection path 92 extending upward from the space 91 between the airtight members of the rotary shafts A1 and A2. 1 and 5, the casing 2 is formed with a casing connection path 93 that is connected to the mounting member connection path 92 and extends to the upstream end of the fourth pump chamber P4. The mounting member internal connecting path 92 and the casing internal connecting path 93 constitute the airtight member space connecting path (92 + 93) of the first embodiment. Due to the space between the airtight members (92 + 93), the pressure in the space between the airtight members 91 becomes the same pressure as that of the fourth pump chamber P4 where the gas is compressed and the pressure is higher than that of the second pump chamber P2.

(Description of isobar piping structure in gear chamber)
6A and 6B are explanatory diagrams of the isobaric piping structure of the gear chamber according to the first embodiment. FIG. 6A is an enlarged explanatory view of the isobaric piping structure. FIG. 6B is an enlarged view of the rear end portion of the rotating shaft including the isostatic piping structure. It is explanatory drawing.
1 and 6, the rear bearing mounting member 69 is formed with a rear bearing mounting portion 96 to which the rear bearings 67 and 72 are mounted, and the axial front side (+ X side) of the rear bearing mounting portion 96 is formed. ) Is formed with a rear airtight member support 97.
Like the front bearings 66 and 71, the rear bearings 67 and 72 of the first embodiment are configured by ball bearings (ball rolling bearings), and include outer rings (outer races) 67a and 72a, inner rings (inner races) 67b, 72b and balls (rolling elements) 67c, 72c.

In FIG. 6, the outer rings 67 a and 72 a on the front side in the axial direction of the rear bearings 67 and 72 are fixed to the front end wall of the rear bearing mounting portion 96 through a wave washer 98. The outer rings 67 a and 72 a on the rear side in the axial direction of the rear bearings 67 and 72 are pressed and fixed by the shaft positioning portion 99 a of the shaft positioning member 99 supported on the rear surface of the rear bearing mounting member 69. In the shaft positioning portion 99, a plate-like positioning member main body 99b is fixed to the rear bearing mounting member 69 by a fixing bolt B.
In FIG. 6, a rear seal member (airtight member) 101 is supported by the rear airtight member support portion 97, and the rear seal member 101 is in contact with rotating shafts A1 and A2 whose tips rotate. Thus, inflow and outflow of gas along the axial direction are prevented.

  In FIG. 1, in the first embodiment, an oil reservoir 2a is formed in the casing 2, and a lubricant supply extending upward from the rear bearing mounting portion 96 is supplied to the rear bearing mounting member 69 below the oil reservoir 2a. A path 69a is formed. The rear bearing mounting member 69 is formed with a lubricant discharge path 69 b extending from the lower rear bearing mounting portion 96 and the rear airtight member support portion 97 to the gear chamber 77. The oil reservoir 2a is filled with oil-like lubricant that scatters in the gear chamber 77 as the gears G1 and G2 rotate, and the lubricant is supplied to the rear bearing 67 through the lubricant supply passage 69a. Is done. Then, excess lubricant is returned to the gear chamber 77 through the lower lubricant discharge passage 69b. At this time, since the lubricant discharge path 69b is disposed between the rear seal member 101 and the bearing 67, it is possible to reduce the movement of the lubricant supplied to the bearing 67 toward the rear seal member 101. Can extend the life.

An intermediate chamber 102 is formed between the rear end wall 14 of the casing 2 and the front end surface of the rear bearing mounting member 69.
Connected to the intermediate chamber 102 is a first intermediate chamber connection path 103 formed on the outer wall 21 of the casing 2 and extending upward. In the first intermediate chamber connection path 103, an orifice (flow velocity reduction unit) 104 for reducing the flow rate of gas (reducing the flow velocity) is provided. An upper end of the first intermediate chamber connection path 103 is connected to a connection chamber 106, and a second intermediate chamber connection path 107 extending downward is formed in the connection chamber 106. A filter (lubricant removing member) 108 is provided at the upper end of the second intermediate chamber connection path 107 for removing oil mist in the form of gaseous lubricant as a lubricant.

A third intermediate chamber connection path 109 connected to the gear chamber 77 is connected to the second intermediate chamber connection path 106. In the first embodiment, the third intermediate chamber connection path 109 includes a pair of an upper third intermediate chamber connection path 109a and a lower third intermediate chamber connection path 109b that extend in parallel to the rear. A filter (lubricant removing member) 111 for removing oil mist is provided at the gear chamber 77 side inlet of each of the third intermediate chamber connecting passages 109a and 109b.
The intermediate chamber connection path of the first embodiment in which the gear chamber 77 and the intermediate chamber 102 are connected by the first intermediate chamber connection path 103, the connection chamber 106, the second intermediate chamber connection path 107, and the third intermediate chamber connection path 109 ( 103 + 106 + 107 + 109). That is, an equal pressure piping structure is adopted in which the pressures in the gear chamber 77 and the intermediate chamber 102 are made equal by the intermediate chamber connection path (103 + 106 + 107 + 109).

(Roots pump manufacturing method)
FIG. 7 is an explanatory view of the manufacturing method of the roots pump of the first embodiment, and is an explanatory view showing a state in which the rotating shaft, the lower casing, and the upper casing on which the bearings are mounted are separated.
FIG. 8 is an explanatory view of the manufacturing method of the Roots pump according to the first embodiment, and is an explanatory view showing a state in which the rotating shaft on which the bearing is mounted is supported by the lower casing.
FIG. 9 is an explanatory view of the manufacturing method of the roots pump of the first embodiment, and is an explanatory view when the rotor is phase-matched from the state shown in FIG.
FIG. 10 is an explanatory view of the manufacturing method of the roots pump of the first embodiment, and is an explanatory view showing a state where the upper casing is mounted after the phase alignment shown in FIG. 9 is completed and the jig is removed.

In FIG. 7, when assembling the roots type pump 1 of the first embodiment, first, bearings 66, 67, 71, at both ends with respect to the rotary shafts A1, A2 on which the rotors R1 to R6 are formed in advance by cutting or the like. 72 and the bearing mounting members 68 and 69 are mounted. Next, the rotary shafts A1 and A2 on which the bearings 66, 67, 71, and 72 are mounted are mounted on the lower casing 3 to obtain the state shown in FIG.
In the state shown in FIG. 8, the upper side is opened with the rotary shafts A1 and A2 mounted on the lower casing 3, and therefore, between the rotors R1 to R6 and the wall surfaces of the pump chambers P1 to P6. A clearance gauge can be inserted, and the clearances between all the rotors R1 to R6 and the pump chambers P1 to P6 are measured. Then, based on the measured gaps, the gaps are adjusted by moving the rotary shafts A1 and A2 in the axial direction so that the gaps between the rotors R1 to R6 and the pump chambers P1 to P6 are optimum gaps. The rotary shafts A1 and A2 are adjusted by adjusting the shim (to adjust the gap) between the front surface of the positioning member main body 99b of the shaft positioning member 99 disposed on the rear end side and the rear surface of the rear bearing mounting member 69. Fine adjustment by inserting a thin plate).

In FIG. 9, next, the phase alignment jig 116 is attached to the outer wall 21 a of the lower casing 3. The phase matching jig 116 includes an outer wall supported portion 116a supported by the outer wall, and a rotor contact portion 116b with which the rotors R1 to R6 come into contact. The rotor contact surface 116c of the rotor contact portion 116 is set to form an angle of 45 degrees with respect to the rotation axes A1 and A2.
With the phase adjusting jig 116 mounted, with the driving side rotor R1a in contact with the rotor contact surface 116c, a gap gauge 117 is sandwiched between the driving side rotor R1a and the driven side rotor R1b. Measure the gap. At this time, in Example 1, since the upper part is opened, the gap gauge 117 can be sandwiched between the rotors R1 to R6, and the gaps of all the rotors R1 to R6 can be measured. Then, according to the measured gap, the phase is adjusted by relatively rotating the driven rotor R1b in a direction in which the driven rotor R1b is pressed against the driving side rotor R1a or in a direction in which it is released.

When the phase alignment of the rotors R1 to R6 is completed, the phase alignment jig 116 is removed.
In FIG. 10, when the axial adjustment and phasing of the rotors R1 to R6 are completed, the upper casing 4 is mounted, and thereafter, the gear chamber cover 76, the blowing blades 62, the motor support cover 51, the motor M, and the like are mounted. The roots type pump is assembled by installing sequentially.

(Operation of Example 1)
In the Roots type pump 1 of Example 1 having the above-described configuration, the casing 2 is divided into the lower casing 3 and the upper casing 4, so that the rotary shafts A 1 and A 2 are supported by bearings 66, 67, 71, 72. The upper part is open | released in the state with which the lower casing 3 was mounted | worn (refer FIG. 8, FIG. 9). Therefore, in the prior art, the gap could be measured only in the rotor exposed at the end and the pump chamber, but in Example 1, the gap was measured in all the rotors R1 to R6 and the pump chambers P1 to P6. Can confirm. Therefore, it is not necessary to form an opening or the like in order to confirm all the gaps, and the complexity of the configuration and the increase in cost can be avoided. In addition, since all the gaps can be confirmed, the gaps between the rotors R1 to R6 and the pump chambers P1 to P6 are considered only for the change due to the thermal expansion of the rotors R1 to R6 and the casing 2 due to heat generation during exhaust. It will be better. As a result, since the gap is adjusted based on the accumulated gap as in the prior art, the gap can be adjusted with higher accuracy than when the gap in the unexposed pump chamber is unknown. Therefore, exhaust performance can be improved. In addition, it is not necessary to increase the gaps other than the final stage at the design stage as compared with the prior art in which only the accumulated gaps can be measured, so that the exhaust performance in the pump chambers P1 to P5 other than the final stage can be improved. it can.

Further, since the casing 2 is divided into the lower casing 3 and the upper casing 4, for example, when the pump 1 is cleaned by sucking foreign matter into the pump chambers P1 to P6, the upper casing 4 The pump chambers P1 to P6 can be opened simply by removing the. Therefore, maintenance such as cleaning and readjustment of the clearances and phases of the rotary shafts A1 and A2 can be easily performed. Further, if the rotary shafts A1 and A2 are not removed from the lower casing 3, there is no need to readjust the rotary shafts A1 and A2, and maintenance can be performed simply by reattaching the upper casing 4.
Furthermore, in the Roots type pump 1 of Example 1, since the casing 2 is divided | segmented into the lower casing 3 and the upper casing 4, when performing phase alignment of rotor R1-R6, upper direction is open | released. Therefore, phase alignment of all the rotors R1 to R6 can be performed. Therefore, compared with the prior art in which phase alignment was possible only with an exposed rotor, the pump 1 of Example 1 can perform phase alignment (phase confirmation) with all the rotors R1 to R6, thereby improving reliability. Can do.

Further, in the roots type pump 1 of the first embodiment, the differential pressure between the intermediate chamber 102 and the gear chamber 77 is very small due to the isobaric piping structure. Therefore, even if a temperature change occurs in the gear chamber 77 or the intermediate chamber 102 due to heat generated during the operation of the pump 1, and a differential pressure is likely to be generated due to thermal expansion of the gas, the differential pressure can be suppressed. In particular, the gear chamber 77 and the intermediate chamber 102 may have a high pressure on the gear chamber 77 side or a low pressure depending on the operating state. Therefore, the differential pressure at the both ends of the rear seal member 101 can be reduced by the equal pressure piping structure, abnormal wear of the rear seal member 101 can be prevented, the life of the rear seal member 101 can be extended, and adjacent to each other. Inflow and outflow of gas, particularly oil mist, into the pump chamber P6 can be prevented.
In particular, in the isobaric piping structure of the first embodiment, since the orifice 104 is provided in the intermediate chamber connection path (103 + 106 + 107 + 109), a rapid pressure change can be reduced.
Further, since the lubricating oil is removed from the oil mist by the filters 108 and 111, the oil can be prevented from entering the intermediate chamber 102 and the pump chamber P6.
Furthermore, in the first embodiment, the third intermediate chamber connection path 109 has the upper third intermediate chamber connection path 109a and the lower third intermediate chamber connection path 109b, so that the lubricant removed by the filter 108 is assumed. Even if the liquid drops downward from the filter 108 and enters the lower third intermediate chamber connection path 109b to close the lower third intermediate chamber connection path 109b, the upper third intermediate chamber connection path 109a The air connection between the chamber 102 and the gear chamber 77 can be maintained, and the function of the isobaric piping structure can be maintained. Therefore, the lifetime of the isobaric piping structure can be extended.

Further, in the Roots type pump 1 of the first embodiment, a two-stage seal structure of a front first seal member 86 and a front second seal member 87 is employed on the front side of the rotation shafts A1 and A2 having a relatively high degree of vacuum. Therefore, outflow and inflow of gas are reduced, and exhaust performance can be improved. In addition, even if one of the sealing members is damaged, the sealing is performed by the other sealing member, so that a reduction in exhaust performance can be prevented.
In particular, in the Roots type pump 1 of the first embodiment, the space 91 between the airtight members between the front first seal member 86 and the front second seal member 87 having a two-stage seal structure is an airtight member space connection path. It is connected to the fourth pump chamber P4 by (92 + 93). Accordingly, the pressure difference between the axial sides of the front second seal member 87 becomes the pressure difference between the second pump chamber P2 and the fourth pump chamber P4, and the pressure difference between the axial sides of the front first seal member 86. However, this is the pressure difference between the fourth pump chamber P4 and the drive connection chamber 52 (atmospheric pressure). As a result, the space connection path (92 + 93) between the airtight members is not formed, and the pressure difference between the axial sides of the front seal members 86 and 87 becomes the pressure difference between the second pump chamber P2 and the drive connection chamber 52. Compared to the case, the pressure difference between both sides of each of the seal members 86 and 87 is reduced. Therefore, wear of the sealing members 86 and 87 is reduced, gas inflow is reduced, and airtightness is easily maintained.

  Furthermore, in the Roots type pump 1 of the first embodiment, the lubricant outflow prevention space 88 formed between the front bearings 66 and 71 and the front seal member 86 is large by the lubricant outflow prevention connection paths 89 and 84a. It is connected to the drive connection chamber 52 of atmospheric pressure. Therefore, the lubricant outflow prevention connection passages 89 and 84a reduce the pressure difference between the axial sides of the front bearings 66 and 71, making it difficult for gas to move through the inside of the front bearings 66 and 71. It is difficult for the grease used in the movement. As a result, even when the front side seal members 86 and 87 are broken and the seal becomes insufficient, the gas moves to the second pump chamber P2 side through the lubricant outflow prevention connection path 89 and the bearings 66 and 71. It is possible to reduce the leakage of the grease used in the container. As a result, the life of the bearings 66 and 71 can be extended.

Moreover, in the Roots type pump 1 of Example 1, with the rotation of rotating shaft A1, A2, it sends with air to the fins 41a and 42a for cooling by the ventilation blade (53 + 62), and the casing 2 is cooled. Therefore, the exhausted gas and the gas in each of the pump chambers P1 to P6 can be cooled, the temperature rise of the pump 1 can be reduced, and the decrease in exhaust efficiency can be suppressed.
Further, in the first embodiment, even if the casing 2 or the like uses an aluminum material with good cooling performance, the bearing portions 66 to 72 use the same material as the rotors R1 to R6. Compared with the case where the materials of the rotors R1 to R6 are different, the dimensional change due to the thermal expansion of the bearing portions 66 to 72 can be minimized.

In the first embodiment, the pump chambers P1 to P6 are arranged such that the second pump chamber P2 at the second stage is arranged at the front end. In the prior art in which the first pump chamber P1 having a lower pressure than the second pump chamber P2 is disposed at the end, the atmospheric pressure difference (differential pressure) between the first pump chamber P1 and the drive connection chamber 52 becomes large, and the gas However, in Example 1 in which the second pump chamber P2 is located at the end, the differential pressure is small, so that it is difficult for gas to flow in. As a result, the reduction in the ultimate vacuum is reduced, and even if the front seal members 86 and 78 are deteriorated, the influence on the ultimate vacuum can be reduced.
Further, in the first embodiment, by adjusting the volume ratio of the pump chambers P1 to P6, in the process in which the heat is exhausted by the operation of the pump 1 and the pressure is reduced, The heat generation in the two-pump chamber P2 is set to be the largest. Therefore, in the pump 1 of Example 1, since the 2nd pump chamber P2 with the largest heat_generation | fever is arrange | positioned in the most upstream side ventilated by the ventilation blade (53 + 62), it can cool effectively.

  Moreover, in Example 1, the 2nd pump chamber P2, the downstream of the 3rd pump chamber P3, and the exhaust part 33 are connected, and it is not from the 6th pump chamber P6 which is the last stage, but in the middle stage. Exhaust from a certain second pump chamber P2 or third pump chamber P3 is possible. Therefore, immediately after the start of evacuation, in a state in which the pressure in the vacuum chamber connected to the exhaust port 26 has not decreased so much, if the intermediate stage exhaust is not provided, the gas will be excessive in the sixth pump chamber P6 as the final stage. There is a problem that the load torque of the motor M becomes excessive due to the compression state. On the other hand, in Example 1, when the differential pressure between the pressure of the gas compressed on the downstream side of the second pump chamber P2 and the pressure of the exhaust part 33 is the differential pressure that opens the check valve 34a. Is exhausted in the intermediate stage from the second pump chamber P2 to the exhaust section 33, and over-compression in the third pump chamber P3 to the sixth pump chamber P6 on the downstream side can be suppressed. Similarly, even if the exhaust of the vacuum chamber advances, the pressure in the second pump chamber P2 decreases and the check valve 34a closes, the pressure on the downstream side of the third pump chamber P3 opens the check valve 36a. If it is, the intermediate stage exhaust is performed from the third pump chamber P3, and the overcompression on the downstream side can be reduced. Therefore, in the first embodiment, the load torque of the motor M can also be reduced by the intermediate stage exhaust. As a result, a general-purpose general-purpose motor (such as an AC motor) can be used to reduce costs without using a relatively expensive DC brushless motor or canned motor that is generally used in a vacuum pump. Is also possible.

  Furthermore, in the pump 1 of the first embodiment, the width of the exhaust part 33 in the front-rear direction is formed to be greater than the width of the second pump chamber P2 to the sixth pump chamber P6 and has a relatively large volume. In general, if the temperature difference is large in each part of the pump 1, the casing 2 may be deformed abnormally. However, since the exhaust part 33 is compressed and contains high-temperature gas, almost the entire area of the pump 1 is stored. Can be made uniform. In particular, immediately after the operation of the pump 1, the pump 1 is not sufficiently warmed. Therefore, when a condensable gas (for example, water vapor) is sucked from the vacuum chamber to which the intake port 26 is connected, the gas inside the pump chambers P <b> 1 to P <b> 6 Condensation may occur. Therefore, when sucking the condensable gas, the pump 1 may be warmed up in advance. At this time, in the pump 1 of the first embodiment, the temperature of the pump 1 can be made uniform efficiently and quickly by the high-temperature gas in the exhaust part 33. And the silencer 38 is arrange | positioned in the said exhaust part 33, and the pump 1 of Example 1 is space-saving.

(Example of change)
As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the said Example, A various change is performed within the range of the summary of this invention described in the claim. It is possible. Modification examples (H01) to (H012) of the present invention are exemplified below.
(H01) In the above embodiment, the bearings 66, 67, 71, 72 are supported by the casing 2 via the bearing mounting members 68, 69. However, the present invention is not limited to this configuration. It is also possible to adopt a configuration that is supported by.
(H02) In the above embodiment, the method of phase alignment of the rotors R1 to R6 is not limited to the one illustrated in the embodiment, and the phase can be adjusted by any conventionally known method. Further, although phase adjustment is performed after fine adjustment in the axial direction of the rotation axes A1 and A2 at the time of assembly, it is also possible to perform adjustment in the axial direction after performing phase alignment.

(H03) In the above embodiment, the rotors R1 to R6 are two-leaf cages, but the invention is not limited to this, and as described in Patent Document 1, the shape of the rotor such as three-leaf, four-leaf, six-leaf, etc. Can have any shape. In addition, when the shape of the rotor is other than two leaves, the inclination angle of the contact surface 116c of the phase adjusting jig 116 is not 45 degrees.
(H04) In the above-described embodiment, the outer shapes of the rotors R1 to R6 are exemplified by a circular arc and an envelope curve. However, the outer shape is not limited to this. It is also possible.
(H05) In the above embodiment, it is desirable to provide an isobaric piping structure, but it is possible to omit it.

(H06) In the above-described embodiment, it is desirable to provide a two-stage seal structure with the front-side seal members 86 and 87 and a configuration to connect to the fourth pump chamber P4 by the space connection path (92 + 93) between the airtight members, but they are omitted. It is also possible. Further, the pump chamber to which the space connection path (92 + 93) between the airtight members is connected is not limited to the fourth pump chamber P4, and the pump has a smaller volume than the second pump chamber P2 that is the adjacent pump chamber, that is, a high pressure. Any chamber can be used as long as it is a chamber.
(H07) In the above-described embodiment, it is desirable to adopt a configuration that prevents the grease from leaking out by the lubricant outflow prevention space 88 and the lubricant outflow prevention connection paths 89 and 84a, but may be omitted. .
(H08) In the above-described embodiment, the air cooling method using the fins 41a and 42a and the fan (53 + 62) is adopted for cooling the casing 2. However, the present invention is not limited to this configuration. It is also possible to adopt a cooling method.

(H09) In the above-described embodiment, the pump chambers P1 to P6 have a total of six, that is, are configured to be compressed and exhausted in six stages, but are not limited to this, depending on the design, specifications, purpose of use, etc. Thus, the number of stages of the pump chamber can be arbitrarily changed.
(H010) In the above-described embodiment, the second pump chamber P2 is disposed at the end among the pump chambers P1 to P6. However, the present invention is not limited to this, and the third pump chamber P3 may be disposed at the end. In this case, for example, the third pump chamber, the second pump chamber, the first pump chamber, the fourth pump chamber, the fifth pump chamber, and the sixth pump chamber may be arranged sequentially from the front side. In addition, it is desirable to arrange a pump chamber other than the first pump chamber P1 at the end from the viewpoint of ultimate vacuum, but it is also possible to arrange the first pump chamber P1 at the end as in the conventional case.

(H011) In the above embodiment, the configuration in which the intermediate stage exhaust is performed from the second pump chamber P2 and the third pump chamber P3 is illustrated, but the present invention is not limited to this, and the intermediate stage exhaust is omitted or the intermediate stage exhaust is performed. It is possible to use only the second pump chamber P2 or a configuration in which the intermediate stage exhaust can be performed from all the intermediate stage pump chambers P2 to P5.
(H012) In the above embodiment, the lubricant and the grease are exemplified as the lubricant. However, the lubricant is not limited to this, and a conventionally known lubricant that can be used can be used.

Claims (11)

A pair of rotating shafts arranged in parallel;
A rotor provided on each rotating shaft;
A bearing that supports the rotating shaft;
A casing having an intake port for sucking in gas, a pump chamber in which the rotor is accommodated and gas sucked from the intake port is transferred downstream in a gas transfer direction, and an exhaust port for exhausting the transferred gas. The casing having a first casing and a second casing divided along the axial direction of the rotating shaft,
The first casing formed with a first bearing support portion for supporting the bearing and a first rotor housing space in which the rotor is housed;
A second bearing support portion that is formed to face the first bearing support portion and supports the bearing, and is formed corresponding to the first rotor housing space and is surrounded by the first rotor housing space. A second rotor housing space that constitutes the pump chamber by a space that is formed, and the second casing,
The plurality of pump chambers having different volumes, the intake port connected to the pump chamber having the largest volume, the exhaust port connected to the pump chamber having the smallest volume, and the volume in the plurality of pump chambers. And a connection path for connecting gas so as to be sequentially transferred from the large pump chamber to the small pump chamber, where m and n are positive integers, and m ≦ (n / 2 ), The first pump chamber, the second pump chamber,..., The m−1th pump chamber, the mth pump chamber, the m + 1 pump chamber,..., The n−1 pump chamber, the nth. In the case of the pump chamber, the m-th pump chamber, the m-1 pump chamber, the m-2 pump chamber, from the axial one end side to the axial other end side with respect to the axial direction of the rotating shaft, ..., 1st pump chamber, m + 1th pump chamber, m + 2 pump chamber ..., and the casing (n-1) th pump chamber, the first n pump chamber is formed,
Roots pump characterized by comprising A pair of rotating shafts arranged in parallel;
A rotor provided on each rotating shaft;
A bearing that supports the rotating shaft;
A casing having an intake port for sucking in gas, a pump chamber in which the rotor is accommodated and gas sucked from the intake port is transferred downstream in a gas transfer direction, and an exhaust port for exhausting the transferred gas. The casing having a first casing and a second casing divided along the axial direction of the rotating shaft,
The first casing formed with a first bearing support portion for supporting the bearing and a first rotor housing space in which the rotor is housed;
A second bearing support portion that is formed to face the first bearing support portion and supports the bearing, and is formed corresponding to the first rotor housing space and is surrounded by the first rotor housing space. A second rotor housing space that constitutes the pump chamber by a space that is formed, and the second casing,
The plurality of pump chambers having different volumes, the intake port connected to the pump chamber having the largest volume, the exhaust port connected to the pump chamber having the smallest volume, and the volume in the plurality of pump chambers. A casing for connecting gas so that gas is sequentially transferred from the large pump chamber to the small volume pump chamber, wherein k and n are positive integers, k <n, In order from the largest pump chamber, the first pump chamber, the second pump chamber, ..., the k-1 pump chamber, the kth pump chamber, the k + 1 pump chamber, ..., the n-1 pump chamber, the nth pump chamber. If, said casing having an intermediate stage exhaust path for exhausting from the k pump chamber and the outlet port and the first k pump chamber by connecting,
Features and to Lulu over Roots pump further comprising a. An airtight member support formed between the bearing and the adjacent pump chamber, which is a pump chamber disposed adjacent to the bearing of the rotating shaft, with respect to the axial direction of the rotating shaft;
A plurality of the airtight members arranged on the airtight member support portion to prevent gas from leaking along the rotation axis, the airtight members being spaced apart along the axial direction. When,
A space connecting path between the airtight members connecting the pump chamber having a smaller volume than the adjacent pump chamber and the space between the airtight members;
The Roots type pump according to claim 1 or 2 characterized by things. A pair of rotating shafts arranged in parallel;
A rotor provided on each rotating shaft;
A bearing that supports the rotating shaft;
A casing having an intake port for sucking in gas, a pump chamber in which the rotor is accommodated and gas sucked from the intake port is transferred downstream in a gas transfer direction, and an exhaust port for exhausting the transferred gas. The casing having a first casing and a second casing divided along the axial direction of the rotating shaft,
The first casing formed with a first bearing support portion for supporting the bearing and a first rotor housing space in which the rotor is housed;
A second bearing support portion that is formed to face the first bearing support portion and supports the bearing, and is formed corresponding to the first rotor housing space and is surrounded by the first rotor housing space. A second rotor housing space that constitutes the pump chamber by a space that is formed, and the second casing,
An airtight member support formed between the adjacent pump chamber and the bearing support, which is a pump chamber disposed adjacent to the bearing of the rotary shaft with respect to the axial direction of the rotary shaft;
An airtight member arranged on the airtight member support portion to prevent gas from leaking along the rotation axis;
Lubricant outflow that connects between the lubricant outflow prevention space formed between the airtight member and the bearing, and the atmosphere side space on the opposite side of the lubricant outflow prevention space in the axial direction with respect to the bearing. Prevention connection path,
Features and to Lulu over Roots pump further comprising a. A pair of rotating shafts arranged in parallel;
A rotor provided on each rotating shaft;
A bearing that supports the rotating shaft;
A casing having an intake port for sucking in gas, a pump chamber in which the rotor is accommodated and gas sucked from the intake port is transferred downstream in a gas transfer direction, and an exhaust port for exhausting the transferred gas. The casing having a first casing and a second casing divided along the axial direction of the rotating shaft,
The first casing formed with a first bearing support portion for supporting the bearing and a first rotor housing space in which the rotor is housed;
A second bearing support portion that is formed to face the first bearing support portion and supports the bearing, and is formed corresponding to the first rotor housing space and is surrounded by the first rotor housing space. A second rotor housing space that constitutes the pump chamber by a space that is formed, and the second casing,
A gear chamber that is disposed on one end side of the rotary shaft and that transmits rotation between a pair of rotary shafts; and a gear chamber in which a lubricant for lubricating the gear row is stored;
An intermediate chamber disposed between the gear chamber and the pump chamber along the axial direction of the rotation shaft;
An intermediate chamber connection path connecting the gear chamber and the intermediate chamber;
Features and to Lulu over Roots pump further comprising a. A lubricant removing member that is disposed in the intermediate chamber connection path and removes the gaseous lubricant from the gear chamber to the intermediate chamber;
A flow rate reduction unit that is provided in the intermediate chamber connection path and reduces the flow rate of the moving gas;
The Roots type pump according to claim 5 provided with these. A pair of rotating shafts arranged in parallel;
A rotor provided on each rotating shaft;
A bearing that supports the rotating shaft;
A casing having an intake port for sucking in gas, a pump chamber in which the rotor is accommodated and gas sucked from the intake port is transferred downstream in a gas transfer direction, and an exhaust port for exhausting the transferred gas. The casing having a first casing and a second casing divided along the axial direction of the rotating shaft,
The first casing formed with a first bearing support portion for supporting the bearing and a first rotor housing space in which the rotor is housed;
A second bearing support portion that is formed to face the first bearing support portion and supports the bearing, and is formed corresponding to the first rotor housing space and is surrounded by the first rotor housing space. A second rotor housing space that constitutes the pump chamber by a space that is formed, and the second casing,
And cooling fins for enlarging the surface area of the heat radiation is provided in the casing,
Features and to Lulu over Roots pump further comprising a. A blower blade that is supported by the rotating shaft and blows air to the cooling fins as the rotating shaft rotates.
The Roots type pump according to claim 7 characterized by things. A pair of rotating shafts arranged in parallel;
A rotor provided on each rotating shaft;
A bearing that supports the rotating shaft;
A casing having an intake port for sucking in gas, a pump chamber in which the rotor is accommodated and gas sucked from the intake port is transferred downstream in a gas transfer direction, and an exhaust port for exhausting the transferred gas. The casing having a first casing and a second casing divided along the axial direction of the rotating shaft,
The first casing formed with a first bearing support portion for supporting the bearing and a first rotor housing space in which the rotor is housed;
A second bearing support portion that is formed to face the first bearing support portion and supports the bearing, and is formed corresponding to the first rotor housing space and is surrounded by the first rotor housing space. A second rotor housing space that constitutes the pump chamber by a space that is formed, and the second casing,
Disposed in the casing interior in the vicinity of the exhaust port, the muffler for performing mute,
Features and to Lulu over Roots pump further comprising a. A bearing mounting step of mounting a bearing on both ends of each rotating shaft with respect to a pair of rotating shafts provided with a rotor;
A shaft support that supports the bearings of a pair of rotating shafts arranged in parallel in the first casing in which a first bearing support portion that supports the bearings and a first rotor housing space in which the rotor is housed is formed. Process,
A gap adjusting step for adjusting a gap between each rotor of the rotating shaft and a wall surface of the first rotor accommodating space;
The second bearing support portion that is formed to face the first bearing support portion and supports the bearing, is formed corresponding to the first rotor housing space, and is surrounded by the first rotor housing space. The second casing having a second rotor accommodating space that constitutes the pump chamber by a space is mounted on the first casing, and the rotating shaft and the rotor are sandwiched between the first casing and the second casing. A casing assembly process for assembling the casing;
Roots type pump manufacturing method characterized by performing. A jig mounting step of mounting a phase matching jig, which is supported on the first casing and held in a non-rotatable state in contact with an outer peripheral surface of a rotor provided on one of the rotation shafts, on the first casing; ,
A phase matching step for matching the phases of the rotor provided on one rotating shaft and the rotor provided on the other rotating shaft;
A jig removing step of removing the phase matching jig from the first casing;
The Roots-type pump manufacturing method according to claim 10 , wherein: is executed between the shaft support step and the casing assembly step.

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