JPH10238483A - Screw rotary machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent power loss caused by the formation of a vacuum space in a screw rotary machine of asymmetrical tooth profiles. SOLUTION: A screw rotary machine comprises a female rotor 2 of a tooth profile 62 defined by a follower profile curve 64 and a male rotor 1 of a tooth profile 52 defined by a follower profile curve 54 and a forward profile curve 55. The follower profile curve 64 is generated with a generatrix at the point 13 of boundary of the follower profile curve 54 and the forward profile curve 55, and the follower profile curve 54 is generated with a generatrix at the point 21 on the pitch circle of the follower profile curve 64. The follower profile curve 54 of the male rotor 1, that 64 of the female rotor 2, and a suction-side end face 71 of a cylinder enclose a vacuum space 72, which communicates with a suction-side action space by way of an indentation 73 formed in the end face 71. The vacuum space 72 being formed thus communicates with the action space and receives compressible fluid therefrom to have the same pressure as that in the action space, which action prevents power loss in the rotary machine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to compressing a compressible fluid by applying power, or extracting power by expanding a compressed fluid, or transferring compressed or expanded fluid. , Related to screw drill rotating machine.

[0002]

The screw rotating machine is
Two screw rotors including a female rotor and a male rotor that rotate while being in contact with each other about two parallel axes are rotatably housed in a casing, and the working space formed by both rotors and the casing is compressed fluid. , Which is used for the compression or expansion of the female rotor and the male rotor meshing with each other, depending on the cross-sectional shape in a plane perpendicular to the rotation axis of the screw tooth profile of the female rotor and the male rotor. being classified. A screw rotating machine is two screw rotors that rotate while contacting each other around two parallel axes, one of which is a pitch obtained by equally dividing the arc of a pitch circle in a plane perpendicular to the rotation axis by m. A female rotor in which m teeth formed in a substantially arc shape are formed in a pitch circle around a point on the circle, and the other is a pitch circle obtained by equally dividing the arc of the pitch circle in a plane perpendicular to the rotation axis by n. And male and female rotors, each of which is a male rotor in which n teeth formed in a substantially arc shape are formed outside the pitch circle around the point (1).

[0003] In the screw rotating machine of the arc-tooth shape, when the tooth shape of the female rotor is meshed with the tooth shape of the male rotor, the tooth profile curve of one tooth of the female rotor is centered on the contact point of the pitch circle of both rotors. The tooth profile curve of one tooth of the male rotor has the same tooth profile curve as that of the female rotor at the center, and is drawn in the pitch circle of the female rotor with an arc of radius r. The following tooth profile curve on the rear side in the rotation direction and the tooth profile curve on the front side in the rotation direction of the male rotor tooth profile are converted to points on the pitch circle of the female rotor tooth profile that contacts the male rotor up to the male rotor pitch circle. Are drawn outside the pitch circle of the male rotor by being connected to the central arcuate tooth profile. In the arcuate screw type rotary machine, since the tooth curve of the female rotor and the tooth curve of the center part of the male rotor are arc tooth curves of the same radius, the tooth curve of the male rotor is immediately separated from the tooth curve of the female rotor. Therefore, the rotors of both sexes are instantaneously engaged with each other, and a large blow-through hole is formed when the rotors of both sexes are engaged with each other. There is a disadvantage of inviting.

[0004]

On the other hand, a screw rotating machine having an asymmetrical tooth profile has a male part that contacts the main part of the female rotor with the main part of the following tooth profile curve on the rear side in the rotation direction of the tooth profile of the female rotor. A curve created by a point or curve on the following tooth profile curve that is the boundary between the following tooth profile curve on the rear side in the rotation direction and the forward profile tooth curve on the front side in the rotation direction of the rotor tooth profile, and the trailing side on the rear side in the rotation direction of the male rotor. The main part of the curve
A curve formed by a point on the pitch circle of the follow-up tooth profile curve on the rear side in the rotation direction of the tooth profile of the female rotor contacting the main part of the male rotor or a curve forming a tooth profile in the pitch circle in close proximity to the point; Is what you do.

The screw rotating machine having an asymmetrical tooth profile is based on a trailing tooth profile curve on the rear side in the rotational direction which is a boundary between a trailing profile tooth curve on the rear side in the rotational direction and a forward profile tooth curve on the front side in the rotational direction of the tooth profile of the male rotor on the driving side. Point or part of the curve first contacts the main part of the following tooth profile curve on the rear side in the rotational direction of the tooth profile of the female rotor, and separates the suction-side working space and the discharge-side working space of the cylinder. While maintaining the seal, the main part of the trailing profile of the male rotor in the rotational direction is the pitch of the trailing profile of the female rotor in the rotational direction of the tooth profile of the female rotor in contact with the main part of the male rotor. A seal formed by contacting a curve formed by a point on a circle or a curve forming a tooth profile in a pitch circle in the vicinity of the point to separate a suction-side working space and a discharge-side working space of a cylinder from the seal. The tooth profile of the male rotor following the tooth profile And a follower profile of the tooth profile of the female rotor and a suction side end surface of the cylinder to form a vacuum space, and the vacuum space increases in volume with rotation of the male and female rotors. Since the opening and closing are repeated without delay, the power required to create this vacuum space is irrelevant to the compression operation, so that a power loss is involved.

[0006]

SUMMARY OF THE INVENTION The present invention provides two screw rotors which rotate about two parallel axes while contacting each other, one of which is a pitch circle in a plane perpendicular to the axis of rotation. A female rotor in which m teeth are formed in a pitch circle in a substantially arc shape with a center on a point on the pitch circle obtained by dividing the arc of the circle by m, and the other is the arc of the pitch circle in a plane perpendicular to its rotation axis. Is a male rotor in which n teeth formed in a substantially arc shape are formed outside the pitch circle around a point on the pitch circle obtained by equally dividing n, and the rotation direction of the tooth profile of the female rotor The main part of the trailing profile tooth on the rear side is the following tooth profile that is the boundary between the trailing profile curve on the rear side in the rotational direction of the tooth profile of the male rotor that contacts the main part of the female rotor and the forward profile tooth curve on the front side in the rotational direction. A song created by a point on a curve or a curve The main part of the following tooth profile curve on the rear side in the rotation direction of the male rotor is defined as the point on the pitch circle of the following tooth profile curve on the rear side in the rotation direction of the tooth profile of the female rotor in contact with the main part of the male rotor or In a screw rotating machine having an asymmetrical tooth profile formed by a curve that forms a tooth profile in a pitch circle in close proximity to a point, a following tooth profile curve of a male rotor, a following tooth profile curve of a female rotor, and a suction side of a cylinder. The vacuum space surrounded by the end surface is communicated with the suction-side working space via a recess formed in the suction-side end surface of the cylinder.

The present invention is also directed to two screw rotors which rotate around two parallel axes while contacting each other, and one of the screw rotors defines an arc of a pitch circle on a plane perpendicular to the rotation axis as m or the like. Forming m large tooth shapes drawn in a substantially arc shape in the pitch circle around the point on the divided pitch circle,
A female rotor in which a small addendum is formed outside the pitch circle between the arc-shaped tooth profiles in the pitch circle, and the other is a point on the pitch circle obtained by equally dividing the arc of the pitch circle in a plane perpendicular to the rotation axis by n. As a center, it is a male rotor in which n large tooth shapes drawn in a substantially arc shape are formed outside the pitch circle, and a small denden dam is formed in the pitch circle between each arc shape tooth outside the pitch circle. With male and female rotors, the main part of the trailing-side tooth profile curve in the rotational direction rear of the female rotor tooth profile is the same as the rotational direction trailing trailing tooth profile curve of the male rotor tooth profile in contact with the main part of the female rotor. A curve or a curve created by a point or a curve on the following tooth profile curve that corresponds to the boundary of the forward tooth profile curve on the front side in the rotation direction, and the main part of the following tooth profile curve on the rear side in the rotation direction of the male rotor is used as the main part of the male rotor. How to rotate the tooth profile of the contacting female rotor In a screw-rotating machine with an asymmetrical tooth profile, which is a curve created by a point on the pitch circle of the trailing tooth profile curve on the rear side or a curve forming a tooth profile in the pitch circle in the vicinity of the point, the trailing tooth profile curve of the male rotor And a vacuum space surrounded by the follower-side tooth profile curve of the female rotor and the suction-side end face of the cylinder, which communicates with the suction-side working space via a recess formed in the suction-side end face of the cylinder.

[0008]

FIG. 1 is a cross-sectional view of one embodiment of the present invention, which is perpendicular to the rotating shafts 3, 4. FIG. 2 is a cross-sectional view of a pair of male and female rotors 1, 2 parallel to the rotating shafts 3, 4. FIG. 3 is a sectional view taken along line AA of FIG. The screw rotating machine comprises two screw rotors rotating around two parallel axes 3 and 4 while contacting each other, and includes a male rotor 1 and a female rotor 2. The female rotor 2 has m tooth profiles 62 in which an arc having a radius r is drawn in an arc around a point 61 on the pitch circle 6 obtained by equally dividing the arc of the pitch circle 6 in a plane perpendicular to the rotation axis 4 into m. The female rotor 2 formed in the pitch circle 6
Are formed in a tooth tip portion 63 corresponding to the arc of the pitch circle 6. The male rotor 1 has n tooth profiles 52 drawn in an arc shape with a radius r around a point 51 on the pitch circle 5 obtained by equally dividing the arc of the pitch circle 5 in a plane perpendicular to the rotation axis 3 into n. 5 outside, male rotor 1
Are formed in a tooth root portion 53 that coincides with the arc of the pitch circle 5. Male rotor 1 and female rotor 2
Means that the rotating shafts 3 and 4 of both rotors 1 and 2 are parallel, and the tooth profiles 52 and 62 of both rotors 1 and 2 are engaged with each other in a state of contact with each other so that the diameter is equal to the outer diameter of each rotor 1 A casing having a cylinder having two equal cylindrical spaces, the distance between the axes thereof is equal to the distance between the two shafts 3 and 4, and the axial length is the same as the axial length of both rotors 1 and 2. 9
And the rotors 1 and 2 are closed at both ends by a suction-side end plate 7 and a discharge-side end plate 8, thereby forming a screw rotating machine.

When the screw rotating machine is operated as a compressor, the male rotor 1 is driven to rotate in the direction of the arrow. The female rotor 2 is engaged with and driven by the male rotor 1. At this time, the tooth profiles on the rear side in the rotation direction of the tooth profile 52 of the male rotor 1 and the tooth profile 62 of the female rotor 2 are respectively replaced with the following tooth profile curves 54 and 64.
, And the tooth profile curves on the front side in the rotation direction are referred to as forward tooth profile curves 55 and 65, respectively. The point of intersection of the trailing tooth profile curve 64 on the rear side in the rotation direction of the female rotor 2 and the pitch circle 6 is point 21, and the point of intersection of the trailing tooth profile curve 54 on the rear side in the rotation direction of the male rotor 1 and the pitch circle 5 is point 11. The main part 66 (reference numeral 2) of the following-side tooth profile curve 64 on the rear side in the rotation direction of the tooth profile 62 of the female rotor 2
1, 23) to the tooth profile 5 of the male rotor 1 in contact with the main part 66 of the tooth profile 62 of the female rotor 2 (lines 21-23).
2 is a curve created by a point 13 (the end of the following-side tooth profile curve 54) which is a boundary between the following-side tooth profile curve 54 on the rear side in the rotation direction and the forward-side tooth profile curve 55 on the front side in the rotation direction. Main part 56 of the following tooth profile curve 54
(Line between reference numerals 11 and 12) indicates the main part 5 of the male rotor 1.
6 (line 11-12) is a curve created by the point 21 on the pitch circle 6 of the tooth profile 62 of the female rotor 2 that contacts the female rotor 2. In the figure, the tooth profiles 52, 6 of the male and female rotors 1, 2 are shown.
The intersections between the forward-side tooth profile curves 55, 65 on the front side in the rotation direction 2 and the pitch circles 5, 6 are denoted by reference numerals 59, 69, respectively, and the intersection between the forward-side tooth profile curve 55 of the male rotor and the pitch circle 6 is denoted by reference numeral 58. At this time, the curved portion (23
-69) is an arc having a radius r centered on a point 61 on the pitch circle 6 obtained by dividing the arc of the pitch circle 6 by m, and the curved portion (13-59) of the tooth profile 52 of the male rotor 1 is N arc
Curved portion (58-59) is an arc of radius r centered on point 51 on pitch circle 5 equally divided, and intersection of pitch circle 6 with forward-side tooth profile curve 65 on the rotational direction front side of tooth profile 62 of female rotor 2. 69 is a creation curve of 69.

When the male rotor 1 is driven to rotate in the direction of the arrow, the screw compressor of the asymmetrical tooth profile has a following tooth profile curve 54 on the rear side in the rotational direction of the tooth profile 52 of the male rotor 1 and a forward tooth profile curve on the front side in the rotational direction. The point 13 (the end of the following-side tooth profile curve 54) corresponding to the boundary of the point 55 contacts the main part 66 (the line between the reference numerals 21 and 23) of the following-side tooth profile curve 64 on the rear side in the rotation direction of the female rotor 2 at one point. By separating the working space on the suction side (lower side in FIG. 1) and the working space on the discharge side (upper side in FIG. 1) while maintaining the airtightness of the portion, The point 21 comes into contact with the trailing tooth profile curve 54 (line 11-13) on the rear side in the rotation direction of the male rotor 1 at one point, and the suction side working space and the discharge side working space are separated while maintaining the airtightness of the portion. I do. Thereafter, the male and female rotors 1 between the two points,
2. A minimum area where the suction side end plate 7 and the suction side ends of the rotors 1 and 2 contact air-tightly with a gap formed between the follow-up side profile curves 54 and 64 on the rear side in the rotational direction of FIG. When the end face having the shape (referred to as the suction side end face 71) is flat, it is surrounded by the trailing side tooth profile curves 54, 64 on the rear side in the rotation direction of the male and female rotors 1, 2 between the two points and the suction side end face. A space (this is called bakyum space) is created. This space is
Although the volume increases with the rotation of the male and female rotors 1 and 2, even if the operation of expanding the vacuum space is repeated, this gap is used to compress the compressible fluid between the suction-side working space and the discharge-side working space. Power loss occurs because the space is irrelevant.
According to the present invention, the following tooth profile curve 54 of the male rotor 1;
This vacancy space 7 surrounded by the trailing tooth profile curve 64 of the female rotor 2 and the flat suction side end surface 71 of the cylinder.
2 communicates with the suction-side working space via the recess 73 formed in the suction-side end face 71 of the suction-side end plate 7 of the cylinder. Therefore, even if the vacuum space 72 is formed, the compressible fluid is immediately discharged from the suction-side working space. As it flows into the vacuum space and the pressure in the vacuum space becomes the same as the suction side working space,
No power loss occurs.

FIG. 4 is a sectional view of the male and female rotors 1, 2 according to a second embodiment of the present invention, which is perpendicular to the rotating shafts 3, 4. FIG.
The same parts as those shown in FIG. In the second embodiment, the female rotor 2 draws an arc having a radius r in a substantially arc shape around a point 61 on the pitch circle 6 obtained by equally dividing the arc of the pitch circle 6 in a plane perpendicular to the rotation axis 4 by m. The m teeth 62 are formed in the pitch circle 6, and a small addendum 82 is formed outside the pitch circle 6 between the arc-shaped teeth 62 in the pitch circle 6 of the female rotor 2. The male rotor 1 pitches n tooth profiles 52 drawn in a substantially arc shape with a radius r around a point 51 on the pitch circle 5 obtained by equally dividing the arc of the pitch circle 5 in a plane perpendicular to the rotation axis 3 by n. A small denden dam 81 is formed outside the circle 5 and between the arcuate tooth profiles 52 outside the pitch circle 5 of the male rotor 1 so as to increase the space volume in the pitch circle 5.

Point 21 is the intersection of the trailing tooth profile curve 64 on the rear side in the rotation direction of the female rotor 2 and the pitch circle 6, and point 11 is the intersection of the trailing tooth profile curve 54 on the rear side in the rotation direction of the male rotor 1 and the pitch circle 5. In this case, the main part 66 (the line between reference numerals 22 and 23) of the following tooth profile curve 64 on the rear side in the rotation direction of the tooth profile 62 of the female rotor 2 is changed to the main part 66 (line 2
2-23), a curve 12-13 (an end of the following-side tooth profile curve 54) which is a boundary between the trailing-side tooth profile curve 54 of the tooth profile 52 of the male rotor 1 in the rotation direction and the forward-side tooth profile curve 55 of the rotation direction front side. Male rotor 1
The main portion 56 (line between reference numerals 11 and 12) of the trailing tooth profile curve 54 on the rear side in the rotation direction of the male rotor 1 is
This is a curve created by the point 21 on the pitch circle 6 of the tooth profile 62 of the female rotor 2 that contacts the (line 11-12). Due to the formation of the addendum 82 of the tooth profile 62 of the female rotor 2, the distance between the substantially central portion 28 of the addendum 82 and the point 21 of the trailing tooth profile curve 64 on the rear side in the rotational direction of the female rotor 2 is set in the rotational direction of the male rotor 1. The follow-up side tooth profile curve 54 is a curve created by the point 11 of the pitch circle 5. By forming the denden dam 81 of the male rotor 1, the central portion 18 of the denden dam 81 and the tooth profile 52 of the male rotor 1 follow the rotational direction rearward. The curve up to the point 11 (point on the pitch circle 5) of the side tooth profile curve 54 is a curve created by the point 28 of the female rotor 2.

In the present embodiment, the following tooth profile curve 54 (reference numerals 12 and 13) which is the boundary between the following tooth profile curve 54 on the rear side in the rotation direction of the tooth profile 52 of the male rotor 1 and the forward tooth profile curve 55 on the front side in the rotation direction. Are the main parts 66 (reference numeral 2) of the following tooth profile curve 64 on the rear side in the rotation direction of the female rotor 2 on the rear side.
2 and 23) at one point to separate the suction-side working space (lower side in FIG. 4) and the discharge-side working space (upper side in FIG. 4) while maintaining the airtightness of the portion. Next, the tooth profile 6 of the female rotor 2
2 at the point 21 on the pitch circle 6 of the trailing-side tooth profile curve 64 on the rear side in the rotation direction, or the tooth profile 62 in the pitch circle 6 near the point.
Is in contact at one point with the trailing tooth profile curve 54 on the rear side in the rotation direction of the male rotor 1 to separate the suction-side working space and the discharge-side working space while keeping the portion airtight. Even if a gap is formed in the tooth profile 52, 62 between the male and female rotors 1, 2 between the two points and the suction operation is repeated in the space between the two points,
Since this gap is a vacuum space in a vacuum state with no working fluid between the suction-side working space and the discharge-side working space, it leads to power loss. According to the present invention, the following tooth profile curve 54 of the male rotor 1, the following tooth profile curve 64 of the female rotor 2,
Since the vacuum space 72 surrounded by the suction-side end face 71 of the cylinder is communicated with the suction-side working space through a recess 73 formed in the suction-side end face of the cylinder, the suction-side working space is immediately formed even if the vacuum space 72 is formed. , The compressible fluid flows into the vacuum space, and the pressure in the vacuum space becomes equal to that of the suction side working space, so that no power loss occurs.

FIGS. 5 to 10 show the operation of the embodiment of FIG. 4 over time. FIG.
The male rotor 1 is driven to rotate in the direction of the arrow, and one of the tooth profiles 52 is about to mesh with one of the tooth profiles 62 of the female rotor 2, and the forward tooth profile curve 65 on the front side in the rotation direction of the female rotor 2 is male. The forward-side tooth profile curve 55 on the front side in the rotation direction of the rotor 1 is in contact with the forward-side tooth profile curve 54 on the rear side in the rotation direction of the female rotor 2. There is no contact, and the discharge side working space is not sealed with the suction side working space.

Next, when the male rotor 1 is further driven to rotate, as shown in FIG. 6, the line 12-13 of the following tooth profile curve 54 on the rear side in the rotation direction of the male rotor 1 The tooth profile curve 64 of the male rotor 1 is in contact with the line 22-23 of the tooth profile curve 64 on the side (line 12-13).
And a follower profile 64 (line 22-23) of the female rotor 2 to form a seal and begin to separate the discharge working space and the suction working space. When the male rotor 1 further rotates to the state shown in FIG. 7, the line 12-13 of the following tooth profile curve 54 on the rear side in the rotation direction of the male rotor 1 further shows the female rotor 2
Contact the line 22-23 of the trailing tooth profile curve 64 on the rear side in the rotational direction of the male rotor 1 and follow the trailing tooth profile curve 54 (line 12-
13) and the following tooth profile curve 64 of the female rotor 2 (line 22-2).
3), the line 11-12 of the trailing tooth profile curve 64 on the rear side in the rotation direction of the female rotor 2 that contacts the trailing tooth profile curve 54 on the rear side in the rotation direction of the male rotor 1
In contact with the trailing tooth profile curve 52 on the rear side in the rotation direction of the male rotor 1, the sealing of the trailing tooth profile curve 54 of the male rotor 1 and the trailing tooth profile curve 64 of the female rotor 2 starts, as shown in FIG. The back end of the vacuum space 72 is closed to form the vacuum space 72, and separation between the discharge-side working space and the suction-side working space is started.

At this time, a vacuum space 72 is formed, and the vacuum space 72 is formed by the suction-side end face 7 of the suction-side end plate 7.
1, the compressible fluid in the suction-side working space flows freely into the vacuum space 72, and the pressure in the vacuum space becomes the same as the suction-side working space. Even if the vacuum space 72 is formed, no power loss occurs. Further, when the male rotor 1 is driven to rotate, the volume of the vacuum space 72 is increased as shown in FIGS. 8 and 9, but the vacuum space 72 is formed by a depression 73 formed in the suction side end face 71 of the suction end plate 7. Because it is open to
The compressible fluid in the suction-side working space freely flows into the vacuum space 72, and no power loss occurs even if the volume of the vacuum space is enlarged. When the male rotor 1 is rotationally driven in the state shown in FIG. 10, the forward tooth profile curve 55 on the front side in the rotation direction of the male rotor 1 is separated from the forward tooth profile curve 65 on the front side in the rotation direction of the female rotor 2, and the male rotor 1 is rotated. The following tooth profile curve 5 on the rear side in the rotation direction, which is the boundary between the following tooth profile curve 54 on the rear side in the rotation direction and the forward tooth profile curve 55 on the front side in the rotation direction.
4 is also separated from the line 22-23 of the trailing tooth profile curve 64 on the rear side in the rotation direction of the female rotor 2, and the tooth profiles 52, 62 of both rotors 1, 2 forming the vacuum space 72.
One of the seals on the front side in the rotation direction will be opened,
The space 72 is completely eliminated and no power loss occurs.

Although the present invention has been described with reference to the embodiment, the present invention is not limited to the illustrated embodiment, but may be applied to an asymmetric tooth-shaped screw rotating machine within the scope of the technical idea described in the claims. Applicable. In addition, although the operation of the present invention has been described with respect to a compressor, the present invention can be similarly applied not only to a compressor but also to an expander, and to a screw rotating machine for transferring a compressed fluid or an expanded fluid.

[0018]

According to the present invention, there are provided two screw rotors which rotate around two parallel axes while contacting each other,
A female rotor in which m teeth formed in a substantially circular arc shape are formed in the pitch circle, with one of the centers being a point on the pitch circle obtained by equally dividing the arc of the pitch circle on a plane perpendicular to the rotation axis,
The other is a male rotor in which n teeth formed in a substantially arc shape are formed outside the pitch circle, with a center on a point on the pitch circle obtained by equally dividing the arc of the pitch circle in a plane perpendicular to the rotation axis into n. With male and female rotors, the main part of the trailing-side tooth profile curve on the rear side in the rotational direction of the female rotor tooth profile is the same as the trailing direction tooth profile curve on the rotational direction rear of the male rotor tooth profile in contact with the main part of the female rotor. A curve or a curve created by points or curves on the following tooth profile curve that is the boundary of the forward-side tooth profile curve on the front side in the rotation direction, and the main part of the following tooth profile curve on the rear side in the rotation direction of the male rotor is added to the main part of the male rotor. In a screw rotating machine having an asymmetrical tooth profile, a curve is formed by a point on a pitch circle of a follower curve on the rear side in the rotational direction of the tooth profile of a female rotor in contact with the curve or a curve forming a tooth profile in the pitch circle in close proximity to the point. , Male The vacuum space surrounded by the follower side tooth profile curve of the rotor, the follower side profile curve of the female rotor, and the suction side end face of the cylinder communicates with the suction side working space via a recess formed in the suction side end face of the cylinder of the casing. Therefore, the following tooth profile curve 5 of the male rotor 1
4, a follow-up tooth profile curve 64 of the female rotor 2 and a flat suction-side end face 71 of the cylinder of the casing 9 are formed in the suction-side end face 71 of the suction-side end plate 7 of the cylinder. Since it is connected to the suction side working space through the recess 73, even if the vacuum space 72 is formed, the compressible fluid immediately flows into the vacuum space from the suction side working space, and the pressure in the vacuum space becomes the same as that of the suction side working space. No power loss occurs due to pressure. Further, since the contact position between the following-side tooth profile curve 54 of the male rotor 1 and the following-side tooth profile curve 64 of the female rotor 2 is limited, a space is not required for providing the depression 73.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of one embodiment of the present invention, which is perpendicular to a rotation axis.

FIG. 2 is a plan view parallel to the rotation axis.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a cross-sectional view of another embodiment of the present invention, which is perpendicular to the rotation axis.

FIG. 5

FIG. 10 is a diagram showing an operation state of the embodiment of FIG. 4 over time.

[Explanation of symbols]

 1 ... male rotor, 3 ... rotation axis of male rotor, 5 ... pitch circle of male rotor, 51 ... n equal points of pitch arc of male rotor, 52 ... tooth profile of male rotor, 53 ... male Tooth root portion of the rotor, 54: Trailing tooth profile curve on the rear side in the rotation direction of the male rotor, 55 ... Forward tooth profile curve on the front side in the rotation direction of the male rotor, 2 ... Female rotor, 4 ... Rotation of the female rotor Shaft, 6: Female rotor pitch circle, 61: m equidistant point of female rotor pitch arc, 62: Female rotor tooth profile, 63: Female rotor tooth tip, 64: Female rotor rotation Follow-up tooth profile curve on the rear side in the direction, 65: Forward profile tooth profile on the front side in the rotation direction of the female rotor, 7: Suction-side end plate, 71: The suction-side end face, 72: Backspace space, 73: Depression , 8 ... discharge side end plate, 9 ... casing.

Claims (2)

[Claims] 1. Two screw rotors rotating around two parallel axes while contacting each other, one of which is a pitch obtained by equally dividing the arc of a pitch circle in a plane perpendicular to the rotation axis by m. A female rotor in which m teeth formed in a substantially arc shape are formed in a pitch circle around a point on the circle, and the other is a pitch circle obtained by equally dividing the arc of the pitch circle in a plane perpendicular to the rotation axis by n. A male rotor having male and female rotors in which n teeth shapes drawn in a substantially arc shape are formed outside the pitch circle with the center of the point as a center, and a follower-side tooth profile curve on the rear side in the rotational direction of the female rotor tooth profile. The main part is created by a point or curve on the trailing tooth profile curve which is the boundary between the trailing tooth profile curve on the rear side in the rotational direction and the forward profile tooth curve on the front side in the rotational direction of the tooth profile of the male rotor in contact with the main part of the female rotor. And the rotation direction of the male rotor The main part of the trailing profile curve on the rear side is defined as a point on the pitch circle of the trailing profile curve on the rear side in the rotational direction of the tooth profile of the female rotor in contact with the main part of the male rotor or a pitch circle close to the point. In a screw rotating machine with an asymmetrical tooth profile that is a curve created by a curve that constitutes a tooth profile in the inside, a vacuum space surrounded by a following tooth profile curve of a male rotor, a following tooth profile curve of a female rotor, and a suction end surface of a cylinder. Is connected to the suction-side working space via a recess formed in the suction-side end face of the cylinder. 2. A two-screw rotor which rotates while being in contact with each other about two parallel axes, one of which is a pitch obtained by equally dividing an arc of a pitch circle on a plane perpendicular to the rotation axis by m. M large tooth shapes drawn in a substantially arc shape around the point on the circle were formed in the pitch circle, and a small addendum was formed outside the pitch circle between each arc shape tooth in the pitch circle. The female rotor, the other of which is formed with n large tooth shapes outside the pitch circle in a substantially arc shape, centered on a point on the pitch circle obtained by equally dividing the arc of the pitch circle on a plane perpendicular to the rotation axis by n. A male rotor in which a small denden dam is formed in the pitch circle between the arc-shaped tooth profiles outside the pitch circle, having male and female rotors, and a follow-up tooth profile curve on the rear side in the rotational direction of the female rotor tooth profile. The main part of the male rotor that contacts the main part of the female rotor A curve created by a point or curve on the trailing tooth profile curve that is the boundary between the trailing profile curve on the rear side in the rotational direction of the tooth profile and the forward profile curve on the forward side in the rotational direction, and the trailing profile curve on the rear side in the rotational direction of the male rotor. A point on the pitch circle of the following tooth profile curve on the rear side in the rotational direction of the tooth profile of the female rotor that contacts the main portion of the male rotor, or a curve forming a tooth profile in the pitch circle in the vicinity of the point. In the screw rotating machine of an asymmetrical tooth profile having a curve created by the following, the following space is surrounded by the following tooth profile curve of the male rotor, the following tooth profile curve of the female rotor, and the suction side end face of the cylinder. 2. The screw rotating machine according to claim 1, wherein the screw rotating machine communicates with the suction-side working space through a recess formed in the rotary member.