JP2913111B2 - Screw rotor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an oil-cooled screw rotating machine in which a male rotor and a female rotor contact and rotate among screw rotating machines such as a screw compressor or an expander. It relates to the improved screw rotor used.

(Prior art)

Many screw rotating machines provided with a pair of male rotors and female rotors that rotate while meshing with each other about two parallel axes have been proposed. Here, a screw rotating machine that rotates the screw rotor with a driving machine such as an electric motor, compresses gas and sends it from the suction side to the discharge side is called a screw compressor, and introduces high-pressure gas from the inlet side and expands it to the exhaust side. A screw rotating machine that rotates the screw rotor during discharge to recover power is called a screw expander. Hereinafter, the case of a screw compressor will be described unless otherwise specified,
It goes without saying that the present invention can be applied to a screw expander.

Such a screw rotor rotating machine includes a screw rotor, that is, a male rotor and a female rotor. In general, a screw rotor that is often used on the drive side and is used on the driven side, that is, the driven side. Many female rotors have different shapes, and the shape of the peaks of these rotors is often asymmetric between the forward side and the following side. In this case, the male rotor has its major part outside the pitch circle and the female rotor has its major part inside the pitch circle.

The compressor is of a so-called positive displacement type, and compresses or expands gas enclosed in a space surrounded by a male rotor, a casing inner surface, and a casing wall in contact with the rotor end surface. Here, the male rotor and the female rotor form a seal line at the narrowest part of the gap between them.

The gas sealed in the space passes through the gap of the seal line between the rotors, in the case of a compressor, from the discharge side to the suction side,
In the case of an expander, it leaks from the inlet side to the exhaust side to lower the volume ratio. Therefore, the smaller the gap between the seal lines, the better the performance of the screw rotating machine.However, if the gap is too small, the male and female rotors may be seized and the machine may be damaged. It is necessary to secure an appropriate safety clearance in consideration of expansion and the like.

The gap between the rotors of the screw rotor is formed by tooth surfaces of the male rotor and the female rotor machined into a screw shape. Conventionally, a basic tooth profile of a male rotor (a three-dimensional shape in which a predetermined torsion angle is given to a cross section perpendicular to an axis) is uniformly reduced by a predetermined dimension in a normal direction of a tooth surface to obtain a modified tooth profile of a male rotor and a basic tooth profile of a female rotor ( Three-dimensional object with a predetermined torsion angle given to the cross-section perpendicular to the axis)
In this case, a predetermined dimension is uniformly reduced in the normal direction of the tooth surface of the female rotor to produce a modified tooth profile of the female rotor.

There are two types of screw rotating machines.
One is a synchronous type in which the male and female rotors have a timing gear between the shafts, and the screw rotor forms a space for compressing or expanding gas, but the screw rotors themselves do not contact each other. The other is a type in which the timing rotor is not provided, the screw rotors are in contact with each other, for example, the male rotor is rotated from the outside, and the female rotor is driven by the male rotor.

In the latter type, the operation of the screw rotors is minimized in order to minimize the frictional force and wear between the two screw rotors, to cool the rotors and the working fluid that heat up due to the heat of compression of the working fluid, and to further enhance the sealing effect. A lubricant such as oil is injected into the space (in the present invention, a screw rotating machine using this type of screw rotor is referred to as an "oil-cooled screw rotating machine").

In the oil-cooled screw rotating machine, as shown in FIG. 1, the driving rotor and the driven rotor come into direct contact to transmit the rotating torque, so that the gap between the rotors is smaller on the forward side where the contact point is located, It becomes larger on the following side. Therefore, reducing the clearance on the following side leads to an improvement in the performance of the screw compressor. FIG. 1 shows a case where the male rotor is a drive rotor and the female rotor is a driven rotor.

[Problems to be solved by the invention]

However, the modified tooth profile of the male rotor is manufactured by reducing the modified tooth profile of the male rotor uniformly to a predetermined dimension in the normal direction of the tooth surface of the basic tooth profile, and the modified tooth profile of the female rotor is adjusted in the normal direction of the tooth surface of the basic tooth profile. In the method of manufacturing and providing a gap by uniformly reducing the dimension by a predetermined amount, there is a problem that the gap is uneven and large on the follower side of the rotor that is in contact with the rotor during rotation.

The present invention has been made in view of the above points, and eliminates the problems described above, can reduce the amount of leakage without causing a mechanical problem such as seizure between rotors, and improves the performance of a screw rotating machine. An object of the present invention is to provide a screw rotor that can be driven.

[Means for solving the problem]

In order to solve the above problems, the present invention comprises a pair of male and female rotors that rotate while meshing with each other about two parallel axes, and the basic tooth profile of the male rotor in the section perpendicular to the axis and the section in the section perpendicular to the axis. In an oil-cooled screw rotor in which the basic tooth profile of the female rotor meshes with and rotates without any gap in the cross section perpendicular to the axis, the tooth profile of the female rotor in the cross section at right angles to the normal of the basic tooth profile of the female rotor in the cross section perpendicular to the axis The tooth profile of the male rotor in the cross section perpendicular to the axis is uniformly reduced by a predetermined dimension in the direction normal to the basic tooth profile of the male rotor in the cross section perpendicular to the axis to obtain the corrected tooth profile. It is characterized by the following.

[Action]

As described above, the present invention reduces the tooth profile of the female rotor in the cross section perpendicular to the axis to a corrected tooth profile by uniformly reducing the tooth profile of the female rotor in the normal direction of the basic tooth profile of the female rotor in the cross section perpendicular to the axis to obtain a corrected tooth profile. By reducing the tooth profile of the male rotor at a predetermined dimension uniformly in the normal direction of the basic tooth profile of the male rotor in a cross section perpendicular to the axis to obtain a modified tooth profile, the screw rotor using the modified tooth profile can be used as an oil-cooled screw rotating machine. When the male rotor and the female rotor make contact on the forward side as described in detail later in the embodiment, the gap on the following side becomes smaller and more uniform than in the conventional example. Gas leakage can be suppressed.

〔Example〕

Hereinafter, embodiments of the present invention will be described. The basic tooth profile of the male rotor and the female tooth profile of the screw rotor according to the present invention are the same as the basic tooth profile of the male rotor and the female tooth profile of the above-mentioned conventional example. That is, a solid body in which a predetermined torsion angle is given to a cross section of the male rotor perpendicular to the axis and a solid body in which a predetermined torsion angle is given to a cross section of the female rotor perpendicular to the axis. Then, in order to provide a clearance between the rotors, the basic tooth profile of the female rotor is uniformly reduced by a predetermined dimension in the normal direction in a cross section perpendicular to the axis to obtain a modified tooth profile of the female rotor. The corrected tooth profile of the male rotor is reduced by uniformly reducing a predetermined dimension in the linear direction.

When a screw rotor composed of a female rotor and a male rotor having the above-described modified tooth profile is used in an oil-cooled screw rotating machine, when the male rotor and the female rotor contact on the forward side as described in detail later, the follower side The gap is smaller and more uniform than in the conventional example. Hereinafter, the screw rotor according to the present invention will be described in comparison with a conventional example.

FIG. 2 shows the conventional rotor and the screw rotor according to the present invention, in which the advance side of the basic tooth profile 101 of the male rotor M is the female rotor F.
Of the basic tooth profile 102 of the male rotor M, the forward side of the modified tooth profile 103 of the male rotor M does not contact the advanced side of the basic tooth profile 101 of the male rotor M, and the trailing side of the modified tooth profile 104 of the female rotor F FIG. 3 is an explanatory view showing a state where the basic tooth profile does not contact a follow-up side.

FIG. 3 shows the conventional rotor and the screw rotor of the present invention, in which the follower side of the basic tooth profile 101 of the male rotor M contacts the forward side of the basic tooth profile 102 of the female rotor F, and the modified tooth profile 1 of the male rotor M is shown.
03 is not in contact with the follower side of the basic tooth profile 102 of the male rotor M, and the forward side of the modified tooth profile 103 of the female rotor F is the female rotor F
FIG. 4 is an explanatory diagram showing a state where the basic tooth profile 102 does not come into contact with the advance side.

FIG. 4 shows a state in which the female rotor F is fixed from the state shown in FIG. 2 and the male rotor M is slightly rotated in the rotational direction, so that the advanced side of the modified tooth profile 103 'of the male rotor M is the advanced side of the basic tooth profile 101 of the male rotor M. FIG. 9 is an explanatory view showing a state in which the point a on the advance side of the modified tooth profile 103 ′ of the male rotor M contacts a point b on the modified tooth profile 104 ′ of the female rotor F.

FIG. 5 shows a state in which the female rotor F is fixed from the state shown in FIG. 3 and the male rotor is slightly rotated in the rotational direction, so that the forward side of the modified tooth profile 103 'of the male rotor M is the same as the forward side of the basic tooth profile 101 of the male rotor M. When the contact side and at the same time the follower side of the basic tooth profile 101 of the male rotor M contacts the forward side of the basic tooth profile 102 of the female rotor F, the follower side of the modified tooth profile 103 'of the male rotor M and the modified tooth profile 1 of the female rotor F
It is explanatory drawing which shows the state which separated the forward side of 04 '.

In FIG. 2, all points on the forward side of the basic tooth profile 101 of the male rotor M contact the follow-up side of the basic tooth profile 102 of the female rotor F, but the basic tooth profile 101 of the male rotor M is moved in the normal direction of the tooth surface. Not all points on the modified tooth profile 103 of the conventional male rotor M formed by reducing the dimensions uniformly to a predetermined size do not contact the basic tooth profile 101 of the male rotor M. Therefore, all points on the forward side of the modified tooth profile 103 of the conventional male rotor M are the modified tooth profile 10 of the conventional female rotor F.
No contact with follower 4 In the same figure, the male rotor M
All points on the advancing side of the modified tooth profile 103 of the male rotor M of the present invention formed by reducing the basic tooth profile 101 of the male rotor M of the present invention uniformly in the normal direction of the tooth profile in the cross section perpendicular to the axis to a predetermined dimension are all the points of the male rotor M of the present invention. Does not contact the advance side of the basic tooth profile 101. Therefore, all points on the advance side of the modified tooth profile 103 of the male rotor M of the present invention do not contact the trailing side of the modified tooth profile 104 of the female rotor F.

In FIG. 3, all points on the follower side of the basic tooth profile 101 of the male rotor M contact the forward side of the basic tooth profile 102 of the female rotor F, but the basic tooth profile 101 of the male rotor M is moved in the normal direction of the tooth surface. All points on the follow-up side of the modified tooth profile 103 of the conventional male rotor M formed by uniformly reducing the predetermined dimension to the basic tooth profile 1 of the male rotor M
No contact with 01 follower. Therefore, the conventional male rotor M
Does not come into contact with the forward side of the modified tooth profile 104 of the conventional female rotor F.

Further, in the same figure, all the portions on the follow-up side of the modified tooth profile 103 of the male rotor M of the present invention formed by uniformly reducing a predetermined dimension in the normal direction of the tooth profile in a section perpendicular to the axis with the basic tooth profile 101 of the male rotor M are shown. The point does not contact the trailing side of the basic tooth profile 101 of the male rotor M of the present invention. Therefore, the modified tooth profile 103 of the male rotor M of the present invention
The female rotor F does not come into contact with the advancing side of the modified tooth profile 104 at all points on the follow-up side.

In FIG. 4, all points on the forward side of the basic tooth profile 101 of the male rotor M contact the follow-up side of the basic tooth profile 102 of the female rotor F, and the basic tooth profile 101 of the male rotor M is moved in the normal direction of the tooth surface. Only the point a on the advancing side of the modified tooth profile 103 'of the conventional male rotor M formed by reducing uniformly to a predetermined dimension is the basic tooth profile 1 of the male rotor M.
Touches point a of 01. Therefore, only the point a on the forward side of the modified tooth profile 101 of the conventional male rotor M is the basic tooth profile 101 of all the male rotors M other than the point a on the forward side of the modified tooth profile 103 'of the conventional male rotor M. Does not contact the forward side of the vehicle. Therefore, all points other than point a on the forward side of the modified tooth profile 103 'of the male rotor M of the conventional example are the modified tooth profile 104' of the female rotor F of the conventional example.
Does not contact the follower of

Further, in the same figure, a basic tooth profile 101 of the male rotor M is formed by reducing the basic tooth profile 101 of the male rotor M uniformly in a normal direction of the tooth profile in a cross section perpendicular to the axis by a predetermined dimension.
Only the point contacts the point a on the advance side of the basic tooth profile 101 of the male rotor M of the present invention. Accordingly, only the point a on the forward side of the modified tooth profile 103 'of the male rotor M of the present invention contacts only the point b on the trailing side of the modified tooth profile of the female rotor F, but the modified tooth profile of the male rotor M of the present invention. Points other than point a on the advance side of 103 'do not contact the advance side of the basic tooth profile 101 of the male rotor M of the present invention. Therefore, all points other than point a on the forward side of the modified tooth profile 103 'of the male rotor M of the present invention are the modified tooth profile 10' of the female rotor F.
No contact with 4 'follower.

In FIG. 5, all points on the follow-up side of the basic tooth profile 101 of the male rotor M are in contact with the forward side of the basic tooth profile 102 of the female rotor F, but the basic tooth profile 101 of the male rotor M is moved in the normal direction of the tooth surface. All points on the follow-up side of the modified tooth profile 104 'of the conventional male rotor M formed to have a predetermined dimension uniformly reduced do not contact the follow-up side of the basic tooth profile 101 of the male rotor M. Therefore, all points on the follow-up side of the modified tooth profile 103 'of the conventional male rotor M do not come into contact with the forward side of the modified tooth profile 104' of the female rotor F of the conventional example.

Further, in the figure, the basic tooth profile 101 of the male rotor M is formed by uniformly reducing the basic tooth profile 101 in the normal direction of the tooth profile within a section perpendicular to the axis by a predetermined dimension. Does not contact the trailing side of the basic tooth profile 101 of the male rotor M of the present invention. Therefore, the modified tooth profile 10 of the male rotor M of the present invention is
All points on the 3 'follower side are the modified tooth profile 104' of the female rotor F.
Does not contact the forward side of the vehicle.

The basic tooth profile of the female rotor M and the male rotor F of the present invention is the same as the basic tooth profile of the conventional female rotor M and the male rotor F. In FIG. arc centered P ₁ above, the curve BC is an arc, arc curve CE centered P ₃ on Bitch ¥ 107, curve EG center P ₄ on the outer pitch circle 107 centered P ₂ to the pitch circle 107 arc with the curve GH curve is created by the curve g-h of the female rotor F, curve HA 'is a circular arc centered on the center O ₁ of the male rotor. A curve arc, curve bc is to be created in the curve BC of the male rotor M curve ab basic tooth profile 102 of the female rotor F is centered P ₅ on the pitch circle 108, the curve ce is centered on the pitch circle 108 P
_An arc having ₃ ; a curve eg is a curve created on the curve EG of the male rotor M; gh is an arc having a center P ₆ in the pitch circle 108; a curve h
a 'is an arc around the center O ₂ of the female rotor F.

FIG. 6 shows a gap change between the forward side of the modified tooth profile 103 'of the conventional male rotor M and the forward side of the basic tooth profile 101 of the male rotor M in the state of FIG. FIG. 11 is a diagram for explaining a change in a gap between a forward side of the modified tooth profile 103 ′ of the female rotor F and a follow-up side of the modified tooth profile 104 ′ of the female rotor F.

FIG. 7 shows a gap change between the forward side of the modified tooth profile 103 'of the male rotor M of the present invention and the forward side of the basic tooth profile 101 of the male rotor M in the state of FIG. 4, that is, the male rotor M of the present invention. Of the modified tooth profile 103 'of the male rotor M and the modified tooth profile 104 of the female rotor F of the present invention. FIG. 11 is a diagram for explaining a change in a gap between the ′ and the following side.

FIG. 8 is an explanatory diagram for comparing the change in the gap on the forward side in the conventional example in FIG. 6 with the change in the gap on the forward side in the present invention in FIG.

FIG. 9 shows a gap change between the follow-up side of the modified tooth profile 103 'of the conventional male rotor M and the follow-up side of the basic tooth profile 101 of the male rotor M in the state of FIG. FIG. 10 is a diagram for explaining a change in a gap between a follow-up side of the correction tooth profile 103 ′ and a forward side of the correction tooth profile 104 ′ of the female rotor F.

FIG. 10 shows a gap change between the follow-up side of the modified tooth profile 103 'of the male rotor M of the present invention and the follow-up side of the basic tooth profile 101 of the male rotor M in the state of FIG. FIG. 8 is a diagram for explaining a change in a gap between a follow-up side of the modified tooth profile 103 ′ of the male rotor M and a forward side of the basic tooth profile 102 of the female rotor F.

FIG. 11 is an explanatory diagram for comparing the change in the following clearance in the conventional example shown in FIG. 9 with the change in the following clearance according to the present invention shown in FIG.

1 to 11, the subscript “1” indicates a conventional example, and the subscript “2” indicates the present invention. In the drawing, Cn is the distance between the male and female rotors along the normal line of the male rotor tooth surface at the point S when the male and female rotors are not in contact with each other, n
Is a vector having a length of Cn and a direction component of the normal direction of the male rotor tooth surface at the point S, (n) is a projection component of n on a section perpendicular to the axis, and m is a tangential direction of a trajectory circle when S is rotated by Δt. ,
Δt is a small rotation angle (radian) from the male / female rotor non-contact state to the contact state, θ is the angle formed by n and m,
(Θ) is a projection component of an angle formed by n and m onto a section perpendicular to the axis,
S indicates an arbitrary point on the profile of the section perpendicular to the male rotor axis.

From FIG. 6, the actual clearance Cnm ₁ on the forward side of the conventional example is as follows.

Cn ₁ = U → S _10, however, "→" on U → S ₁₀ indicates the distance from point U to S ₁₀ (hereinafter, "→" is the same meaning).

Cn ₁ = S ₁₄ → S ₁₀ C ₁ = S ₁₃ → S ₁₀ = (S ₁₃ → S ₁₀ ) / COSε = (S ₁₂ → S ₁₀ ) · COS (θ ₁ ) / COSε = (S ₁₁ → S ₁₀ ) COS (θ ₁ ) / COSε = (Δt · R) COS (θ ₁ ) / COSε Cnm ₁ = Cn ₁ −C ₁ = Cn ₁ − (Δt · R) COS (θ ₁ ) / COSε (1) From FIG. 7, the actual clearance Cnm ₂ on the forward side of the present invention is as follows.

Cn ₂ = V → S ₂₀ C ₂ = S ₂₃ → S ₂₀ = (S ₂₂ → S ₂₀ ) · COSθ ₂ = (S ₂₁ → S ₂₀ ) · COSθ ₂ = Δt · R · COSθ ₂ Cnm ₂ = Cn ₂ − C ₂ = Cn ₂ −Δt · R · COSθ ₂ (2) From FIG. 8, the actual gap Cnm _{1 of the} present invention and the actual gap Cnm _{2 of the} conventional example are shown.
The magnitude relationship with is as follows.

Cnm ₁ = Cn ₁ − (Δt · R) · COS (θ ₁ ) / COSε (1) Cnm ₂ = Cn ₂ −Δt · R · COS θ ₂ (2) (θ ₁ ) = θ ₂ = θ, Cn ₁ = Cn ₂ = cn, that is, when the actual basic gaps are equal, Cnm ₁ −Cnm ₂ = {Cn ₁ − (Δt · R) · COS (θ ₁ ) / COSε} − ｛Cn ₂
−Δt · R · COSθ ₂ ｝ = − Δt · R · COSθ · {(1 / COSε) −1} <0 (3) Cnm ₁ <Cnm ₂ (4) Therefore, the actual gap Cnm ₁ of the present invention is a conventional example. Is larger than the actual gap Cnm ₂ . From FIG. 9, the actual clearance Cnm ₃ on the following side of the conventional example is shown.
Is as follows:

Cn ₃ = U ₂ → S ₃₀ C ₃ = S ₃₄ → S ₃₀ = (S ₃₄ → S ₃₀ ) / COSε = (S ₃₂ → S ₃₀ ) / COS (θ ₃ ) / COSε = (S ₃₁ → S ₃₀ ) / COS (θ ₃ ) / COSε = (Δt · R) · COS (θ ₃ ) / COSε Cnm ₃ = Cn ₃ + C ₃ = Cn ₃ + (Δt · R) · COS (θ ₃ ) / COSε (5) From FIG. 10, the actual clearance Cnm ₄ on the following side of the present invention is as follows.

Cn ₄ = V ₂ → S ₄₀ C ₄ = S ₄₃ → S ₄₀ = (S ₄₂ → S ₄₀ ) / COSθ ₄ = (S ₄₁ → S ₄₀ ) / COS θ ₄ = Δt · R · COS θ ₄ Cnm ₄ = Cn _{4 + C 4 = Cn 4 + Δt} · R · COSθ 4 (6) the real clearance Cnm ₃ real gap Cnm ₄ the conventional example of the present invention from Figure 11
The magnitude relationship with is as follows.

Cnm ₃ = Cn ₃ + (Δt · R) · COS (θ ₃ ) / COSε (5) Cnm ₄ = Cn ₄ + Δt · R · COSθ ₄ (6) (θ ₃ ) = θ ₄ = θ, Cn ₃ = Cn ₄ = Cn, that is, when the actual basic gaps are equal, Cnm ₃ −Cnm ₄ = ｛Cn ₃ + (Δt · R) · COS (θ ₃ ) / COS
ε｝ − (Cn ₄ + Δt · R · COSθ ₄ ) = Δt · R · COSθ · {1 / COSε) −1}> 0 (7) Cnm ₃ > Cnm ₄ (8) Therefore, the actual gap Cnm _{1 of the} present invention Is smaller than the actual gap Cnm ₂ of the conventional example.

FIG. 3 shows a state in which a conventional screw rotor having a modified tooth profile in which the basic tooth profiles of the male rotor M and the female rotor F are uniformly reduced by 0.025 mm in the normal direction of the tooth surface, respectively, is rotating in contact with the forward side. When the rotor clearance is obtained by using the above formula, the following is obtained.

Gap [mm] Forward side Between A and B: 0.050 to 0.000 Between B and D ... 0.000 to 0.050 Follower side Between D and G ... Between 0.050 and 0.104 Between G and H ... 0.104 0.050 H-A ... 0.050 The screw rotor of the present invention having a modified tooth profile in which the basic tooth profile of the male and female rotors is uniformly reduced by 0.025 mm in the normal direction of the tooth profile in a cross section perpendicular to the axis. When the rotor gap at the time of non-contact is obtained using the above formula, it is as follows.

Clearance [mm] Forward side Between A and B ... 0.050 to 0.031 Between B and D ... 0.031 to 0.050 Follower side Between D and H ... 0.050 to 0.026 to 0.050 Between H and A ... -0.050 As can be seen here, the basic gap Cn is small near the pitch of the root of the male rotor M (around the point B) and large near the tooth tip. The clearance between the rotors when the screw rotor is rotating while contacting on the forward side is obtained as follows by using the above formula.

Clearance [mm] Forward side Between A and B: 0.050 to 0.000 Between B and D ... 0.000 to 0.050 Follower side Between D and G ... Between 0.050 to 0.060 Between G and H ... 0.060 0.050 H-A ... 0.050 As is clear from the above calculation results, the forward side is the side that contacts and transmits the driving force, so it is natural that the gap between the rotors is small. On the follower side where becomes larger, the distribution of the gap is a substantially uniform distribution with a small change width of 0.050 to 0.060 mm. This value is remarkably compared to the non-uniform distribution of the conventional screw rotor having the modified tooth profile uniformly reduced in the normal direction of the tooth flank of the conventional example, and the gap distribution on the following side of the conventional screw rotor having a large variation width of 0.050 to 0.104. Indicates improvement.

As described above, in the screw rotor of the present invention, when the amount by which the basic tooth profile is uniformly reduced in the cross section perpendicular to the axis is reduced, the clearance on the follower side is uniformly reduced, and the follower side that greatly affects the performance of the screw rotating machine is reduced. The amount of leakage is reduced. Therefore, by using this screw, the performance of the screw rotating machine can be greatly improved.

〔The invention's effect〕

As described above, according to the present invention, the following excellent effects can be obtained.

(1) When the screw rotor of the present invention is used in an oil-cooled screw rotating machine, when the male rotor and the female rotor contact each other on the forward side, the gap on the following side becomes small and uniform, so The amount of leakage can be suppressed, and a high-performance oil-cooled screw rotating machine can be obtained.

(2) Even if the amount of reduction of the meat from the basic tooth profile is set to the same value as when the amount is reduced in the normal direction of the tooth surface, the angle of rotation for bringing the male rotor and the female rotor into contact is reduced. , The amount of change in the gap due to the rotation of the screw rotating machine is reduced, and the gap on the follower side is suppressed as a whole, and the performance of the screw rotating machine can be improved.

(3) The basic tooth profile is defined as a tooth profile perpendicular to the axis of the rotor.
Processing can be performed according to the simple rule of uniform reduction in the normal direction of the tooth profile, so similar to the case of uniform reduction in the normal direction of the tooth surface, there is no need for special machine tools or special techniques, Moreover, an accurate screw rotor can be obtained.

[Brief description of the drawings]

FIG. 1 is a view showing a relative relationship between a male rotor and a female rotor during rotation of a screw rotor, FIG. 2 is an explanatory view of a conventional example and a screw rotor of the present invention, and FIG. 3 is a conventional example and a screw rotor of the present invention. FIG. 4 is an explanatory view of a conventional example and a screw rotor of the present invention. FIG. 5 is a view showing a state in which the female rotor is fixed and the male rotor is slightly rotated in the rotational direction from the state of FIG. FIG. 6 is a view for explaining a change in the gap between the advance side of the modified tooth profile of the conventional male rotor and the advance side of the basic tooth profile of the male rotor in the state of FIG. 4 in the state of FIG. 4, and FIG. FIG. 8 is a view for explaining a change in the gap between the forward side of the modified tooth profile of the male rotor of the present invention and the forward side of the basic tooth profile of the male rotor in the state shown in FIG. 8; FIG. 7 is an explanatory diagram for comparing the change in the gap with the change in the gap on the forward side of the present invention in FIG. FIG. 9 is a diagram for explaining a gap change between the follow-up side of the modified tooth profile of the conventional male rotor and the follow-up side of the basic tooth profile of the male rotor in the state of FIG. 5, and FIG. FIG. 11 is a view for explaining a change in the gap between the follow-up side of the modified tooth profile 103 'of the male rotor M of the present invention and the follow-up side of the basic tooth profile 101 of the male rotor M in the state of FIG. FIG. 11 is a diagram for comparing a change in the following clearance of the example with a change in the following clearance of the present invention in FIG. 10; In the figure, M: male rotor, F: female rotor,

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-59-37290 (JP, A) JP-A-1-15483 (JP, A) JP-A-64-15483 (JP, A) 66488 (JP, U) JP-B 63-40279 (JP, B2) JP-B 55-26312 (JP, B2) JP-B 52-4774 (JP, B2) JP-B 1-227241 (JP, B2) Tokiko Sho 45-16872 (JP, B1)

Claims (1)

(57) [Claims] 1. A male rotor having a pair of male rotors and a female rotor which rotate while meshing with each other about two parallel axes, and a basic tooth profile of a male rotor in a cross section perpendicular to the axis and a basic tooth profile of a female rotor in a cross section perpendicular to the axis. Wherein the tooth profile of the female rotor in the cross section perpendicular to the axis is a predetermined dimension in the direction normal to the basic tooth profile of the female rotor in the cross section perpendicular to the axis. In addition to uniformly reducing the corrected tooth profile, the tooth profile of the male rotor in the cross section perpendicular to the axis is uniformly reduced by a predetermined dimension in the normal direction of the basic tooth profile of the male rotor in the cross section perpendicular to the axis to obtain the corrected tooth profile. Characteristic screw rotor.