JPH06200886A - Screw compressor - Google Patents

Abstract

PURPOSE:To reduce vibration and noise followed by torque fluctuation by canceling torque caused by change in pressure distribution of compressive gas. CONSTITUTION:A torque fluctuation absorbing mechanism 11 is provided for the discharge side end section of a screw compressor main body. In this mechanism, a stator 16 is faced to a rotor 15 where both of them are composed of permanent magnets, so that the number of torque fluctuations, identical to the number of teeth times of a male screw rotor 1 per one revolution is produced by means of attraction and resiliency between the stator and the rotor. By this constitution, when the male screw rotor 1 is rotated, inner pressure is accordingly changed, so that exciting force with an intermeshing frequency as a basic frequency is applied to the screw rotor 1 and a casing 3. Particularly torque which rotates the screw rotor 1, is fluctuated so as to be transformed into exciting force in the rotating direction. Since torque fluctuation produced by the torque fluctuation absorbing mechanism 11 is identical in frequency and amplitude to the aforesaid exciting force, but is reverse in phase, torque fluctuation produced is canceled by the mechanism. Accordingly vibration and noise are thereby reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw compressor, and in particular, it cancels torque fluctuations caused by changes in the pressure distribution of compressed gas inside the compressor body, and reduces vibration and noise accompanying torque fluctuations. And the screw compressor.

[0002]

2. Description of the Related Art A screw compressor has less reciprocating motion than a reciprocating compressor, and is therefore characterized by low vibration and noise. However, if observed in detail, the screw compressor also has a vibration source, and although it is smaller than the reciprocating compressor, vibration and noise may be a problem. Especially in recent years, there is an increasing demand for improvement of the living environment and the increasing number of cases where compressors are installed in the same building as humans from a dedicated separate building.
Vibration noise reduction is a major issue. The reason and the nature of the vibration source of the screw compressor will be described later,
The vibration from there is emitted as noise directly from the casing surface or the like, or is emitted as noise after propagating solidly through the pedestal or pedestal. In addition, some of the waves may propagate through the floor or the ground, and may be directly affected by vibration.

The reason and the nature of the vibration source will be described in detail. Rotating the screw rotor requires a certain amount of turbulent torque to compress the gas trapped inside. When a sufficient torque is applied, the screw rotor rotates, and the gas trapped therein is compressed and the pressure distribution changes inside the casing. The driving torque is determined by the pressure distribution inside the casing, but its value changes every moment, and the number of teeth is increased and decreased per revolution.
This is because the meshing state of the screw rotor becomes the same as the number of teeth per rotation, and the internal pressure distribution is reproduced. In terms of frequency, torque fluctuations are repeated at a frequency obtained by multiplying the rotation frequency by the number of teeth, that is, the “meshing frequency”. Therefore, like the separation of the direct current component and the alternating current component in electrical engineering, the time change of torque can be separated into a constant component having a constant positive value and a variable component that repeats at the cycle of the mesh frequency. It can be construed that a fixed component performs compression work and a fluctuating component serves as a vibration source. Also, let's look at the fluctuation component from the viewpoint of frequency. The time transition characteristic of the torque fluctuation is determined by the tooth shape of the screw rotor, the shape of the discharge port, etc., but it is not limited to the sine wave shape.
It may be triangular or sawtooth. Therefore, the frequency component of the torque fluctuation is mainly the meshing frequency, but an integral multiple frequency so-called higher-order component is often included.

The screw compressor body rotates by being supplied with a constant torque component by an electric motor or the like provided outside the screw compressor body. In the prior art, the fluctuation component was not supplied, and the remaining fluctuation component acted as a vibrating force on the screw rotor and the casing to act as a vibration source. The torque supplied by the motor contains a slight torque fluctuation component called torque ripple, but it is sufficiently small compared to the torque fluctuation on the compressor side, so it can be ignored unless it is in a special state such as resonance. .

Fluctuations in the internal pressure act on both the casing and the screw rotor, and in addition to torque fluctuations, they also act as an axial exciting force and a radial exciting force, which are vibration sources.
For the same reason as torque fluctuations, they are vibration sources that have a meshing frequency as a fundamental frequency and include higher-order frequencies.

Several methods have already been known for attempts to prevent these vibrations. For example, JP-A-54-
In Japanese Patent No. 94109, it is described that the pressure applied to a piston (a rotary member in the publication) is used to press a screw rotor in the axial direction to reduce axial vibration. In addition, JP-A-58-20009
No. 3, it is described that a vibration damper (in the terminology of the publication, a vibration damping member) increases a damping coefficient of a vibration system and reduces axial vibration. On the other hand, regarding the vibration damping in the rotation direction, in JP-A-56-75993, the tooth separation vibration in the rotation direction between the male and female screw rotors is generated by magnetizing the screw rotor itself (the tooth surface in the term of the publication). It is stated that it prevents the As a method of simultaneously damping both the axial direction and the rotational direction, Japanese Patent Laid-Open No. 62525/1979 discloses a method of bilaterally symmetric. Japanese Patent Laid-Open No. 60-60286 discloses a method for positively eliminating torque fluctuation.
This is a method of generating torque required to drive a rolling piston compressor, including fluctuation components, in the motor to eliminate excess torque and insufficient torque, and to prevent rotation fluctuations. Has been put into practical use in.

[0007]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
Although the techniques described in Japanese Patent Laid-Open No. 109 and Japanese Patent Laid-Open No. 58-200093 have the effect of suppressing vibration, the vibration force itself still remains, and there is a problem that the vibration reducing effect is insufficient. . Japanese Unexamined Patent Publication No. 56-75993 can be expected to have an effect on the relative rotational vibration between the male and female screw rotors, but has a problem that the vibration damping effect cannot be expected when both males and females vibrate. Further, since the material used for the screw rotor is selected from the viewpoint of processing the tooth profile with high precision, it is usually difficult to realize a screw rotor having a strong residual magnetic force and a strong magnetic force as in the present publication. The method disclosed in Japanese Patent Laid-Open No. 54-62515 can be expected to have a sufficient vibration damping effect, but has a problem that the structure is complicated and the design and manufacturing are difficult. Although the technique according to Japanese Patent Laid-Open No. 60-60286 has a great effect, it is possible only in a relatively low speed region due to the limitation of the control device and the power element. It is impossible to put the screw compressor having a higher rotation speed into practical use than the rolling piston compressor to which the present publication is applied. In addition, there is a problem that it becomes expensive because it requires a dedicated control device.

In view of the above problems, an object of the present invention is to realize a screw compressor with a simple structure, which cancels out torque fluctuations and axial vibrational forces generated by changes in internal pressure distribution, thereby reducing vibration and noise. To do.

[0009]

To solve the above problems, the following means are used.

A torque fluctuation absorbing mechanism is provided on the shaft of at least one of the pair of male and female screw rotors. The torque fluctuation absorbing mechanism is coaxial and includes a rotor and a stator that exert forces on each other. The attractive force or repulsive force between the rotor and the stator is determined by their positional relationship, and the rotation angle of the rotor with respect to the stator gives periodicity. Therefore, the torque required to rotate the rotor with respect to the stator changes periodically with respect to the rotation angle. The torque fluctuation may be a positive torque that acts as a drive source, a negative torque that acts as a load, or an alternating repetition of a drive source and a load. The rotor is fixed to the screw rotor shaft, and the stator is fixed to the fixed-side structural member. The cycle of torque fluctuation is matched with the meshing cycle of the screw rotor on the side where the rotor is fixed. Further, the amplitude and phase of the torque fluctuation are selected to be optimal values for canceling the torque fluctuation of the screw rotor.

In order to reduce the axial vibration, the torque fluctuation absorbing mechanism is further provided with an axial exciting force. The means can be realized by shifting the concentric cylindrical rotor and the stator in the axial direction, or by using the rotor and the stator facing each other in the axial direction. The axial excitation force thus realized is set so that the amplitude is equal and the phase is opposite to the axial excitation force of the screw compressor body.

[0012]

In the present invention, the above-mentioned means act as follows to reduce vibration noise.

The torque fluctuation absorbing mechanism gives the screw rotor a torque of the opposite phase with the same amplitude as the torque fluctuation generated in the screw rotor. In other words, the constant component of the torque required by the screw rotor is supplied by the electric motor as in the conventional case, and the fluctuation component is supplied by the torque fluctuation absorbing mechanism. Then, the torque fluctuation of the screw rotor and the torque fluctuation of the torque fluctuation absorbing mechanism cancel each other out, and the torque fluctuation becomes inconspicuous as a whole. Therefore, even if the electric motor rotates the screw compressor main body with a constant torque, the exciting force does not appear, and it is possible to prevent the generation of vibration and noise due to the exciting force.

The same applies to the damping action of axial vibration.
The exciting force generated by the torque fluctuation absorbing mechanism and the exciting force of the screw compressor body cancel each other out.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a side sectional view of a screw compressor body according to the present invention. The male screw rotor 1 and the female screw rotor 2 mesh with each other and are housed in the casing 3. The wall surface of the bore 5 formed inside the casing 3 and formed of two cylindrical holes that partially overlap each other does not contact the screw rotors 1 and 2 with a slight clearance. In this embodiment, the number of screw teeth is 4 for males and 6 for females. The casing 3 has a divided structure and has a main casing 3a,
It is composed of a suction side casing 3b and a discharge side casing 3c. Each screw rotor has bearings 4a, 4b, 4c, 4d
Is pivotally supported by. Of these, the bearings 4a and 4c are combined bearings including angular contact ball bearings, and receive a thrust force from the discharge side to the suction side due to the pressure of compressed gas. A suction port 7 is provided at the suction side end of the bore inside the casing 3,
It penetrates the outside and the bore. Similarly, a discharge port 8 is provided at the discharge side end of the bore inside the casing 3, and penetrates the outside and the bore. The shapes of the openings of the suction port 7 and the discharge port 8 to the end faces of the bores are optimum from the tooth profile of the screw rotor and the compression ratio. A pulley 9 and a shaft seal 10 are provided at an end portion 13a of the male rotor shaft on the suction port side. The pulley 9 is connected to the output shaft of an electric motor (not shown) provided outside via a belt.

An end plate 1 is provided at the outer end of the main body on the discharge side.
A torque fluctuation absorbing mechanism 11 is provided via 2. The torque fluctuation absorbing mechanism will be described with reference to FIGS. 2 is a side sectional view of the torque fluctuation absorbing mechanism 11, and FIG. 3 is a front sectional view of FIG. 2 as viewed from the left side.

The stator 1 is provided on the inner surface of the absorption mechanism casing 14.
6 is provided, and the rotor 15 is concentrically opposed to the rotor 6, and is fixed to the discharge side 13b of the male rotor shaft via the rotor base 19. There is a gap between the rotor 15 and the stator 16, and the gap prevents foreign matter from being caught or contact due to thermal expansion.
At the same time, the size is convenient for generating the target torque fluctuation. Both the rotor 15 and the stator 16 are made of 8 pieces of permanent magnets, and they are fixed with an adhesive by alternately changing the directions of S and N. The magnetic strength of the permanent magnet is set to a value that causes a torque fluctuation equal to the torque fluctuation of the compressor body, as will be described later. The end surface of the absorption mechanism casing 14 is closed by an end cover 20 made of a non-magnetic material. The entire torque fluctuation absorbing mechanism is fixed to the end plate 12 by the fixing bolt 17. Fixing bolt 1
The hole through which 7 passes is an elongated hole 18, and the fixed angle of the torque fluctuation absorbing mechanism can be arbitrarily selected.

Next, the characteristics of the torque fluctuation absorbing mechanism will be described with reference to FIG. FIG. 4 illustrates the relationship between the rotor position of the torque fluctuation absorbing mechanism and the generated torque. The torque generated by the rotation of the rotor in the direction of the arrow changes sinusoidally. The positions in the graph of the torque generated at each position when the position of the rotor changed from (a) to (b) to (c) to (d) were connected by a line. After (d), the state of (a) again occurs and the sequence is repeated. When the rotor is located at position (a), the permanent magnets repel each other because the same poles are close to each other, but they become neutral in spite of the unstable position with high potential in the direction of rotation, and no torque is generated. . (B)
At the position of, there is a magnet of different polarity at the tip of the rotation direction and it is attracted, and there is a magnet of the same pole in the opposite direction of rotation and it repels
The resultant force is a positive torque that advances the rotation. At the position of (c), the magnets of different polarities face each other, and the magnet becomes stable and neutral, and no torque is generated. At the position of (d), the relationship is opposite to that of (b), and the resultant force is a negative torque that inhibits rotation.
In this way, as the rotor rotates, the torque changes repeatedly in positive and negative alternating sine waves. Since there are eight stators and eight rotors in that cycle, there is a torque fluctuation of four cycles per one rotation of the rotor.

The screw compressor of this embodiment operates as follows.

The pulley 9 rotates from the electric motor via a belt.
Entered in. When the male screw rotor 1 rotates, the female screw rotor 2 meshing with it also rotates. Since the screw rotors rotate in contact with each other, the inside of the bore 5 is continuously supplied with oil. In accordance with the rotation of both screw rotors, the space surrounded by the tooth groove of each screw rotor and the inner wall of the bore, which is called a working chamber, moves from right to left in FIG. The gas that has entered the working chamber through the suction port 7 is compressed while being trapped and transferred, and exits through the discharge port 8. The gas pressure inside the working chamber gradually rises with compression, but at the same time, the position and shape of the working chamber also change. Therefore, the force acting on the screw rotor generated by the pressure of the gas and the force acting on the bore surface as its reaction change with the progress of rotation. Since the change is repeated every time the shape of the working chamber becomes the same, it acts as an exciting force having the mesh frequency as the fundamental frequency. In this embodiment, since the number of teeth of the male screw rotor is four, the meshing frequency is four times the male screw rotor rotation frequency, and four cycles of vibration are generated per one rotation of the male screw rotor. This exciting force becomes a torque fluctuation and an exciting force in the axial direction, and in the conventional screw compressor, it vibrates the screw rotor and the casing and becomes a noise source.

The screw compressor according to the present embodiment cancels the torque fluctuation component by adding the torque fluctuation generated by the torque fluctuation absorbing mechanism to the torque fluctuation. The two have the same frequency at four times the male screw rotor speed, and the amplitude of the fluctuating torque generated by the torque fluctuation absorbing mechanism is equal to the fluctuating torque associated with compression. Also, the slots 18 are used to make adjustments so that the phases are reversed. As a result, the fluctuation of the force that is the exciting force does not go outside, and the vibration and noise are small. It should be noted that the torque fluctuation is caused by the shaft 1 between the screw part and the rotor 15.
Although it appears in the internal stress of 3b and the discharge side casing 3c, since these members have sufficient strength, the vibration is small, and this is not a problem amount.

According to this embodiment, it is only necessary to add a torque fluctuation absorbing mechanism to the discharge side end of the screw compressor body, and vibration noise can be reduced without significantly changing the design. Therefore, it is easy to cope with the case where the screw compressor in use is improved in a short time to reduce vibration, or when the torque fluctuation absorbing mechanism is optionally installed or not installed according to the user's request. .

In the present embodiment, the rotor 15 and the stator 1
Although 6 is a set of 8 permanent magnets, one ring-shaped permanent magnet shown in FIG. 5 may be divided into 8 and the S pole and the N pole may be alternately magnetized. By doing so, the number of assembling steps can be saved and it is suitable for mass production.

The torque fluctuation generated by the torque fluctuation absorbing mechanism is not limited to the sine wave of the mesh frequency. Rotor 1
5 and the permanent magnets forming the stator 16 can be changed in shape, interval, and magnetization to obtain a waveform closer to the torque fluctuation generated by the screw compressor main body. By doing so, the exciting force can be canceled out to higher-order components, and the effect of reducing vibration noise becomes greater.

Next, a second embodiment of the present invention will be described with reference to FIG. The description of the items in this embodiment that are common to the first embodiment will be omitted.

FIG. 6 is a side sectional view of the screw compressor body according to the second embodiment. The torque fluctuation absorbing mechanism 21 is provided between the male screw rotor 1 and the pulley 9 so as to be incorporated in the suction side casing 23. The rotor 25 is fixed to the male rotor shaft 24, and the stator 26 is fixed to the suction side casing 23 so as to face the rotor 25.

The operation of this embodiment is similar to that of the first embodiment,
The torque fluctuation absorption mechanism cancels out the torque fluctuation of the screw compressor body, and reduces the generation of vibration noise.

This embodiment has the following effects. First, there is no additional casing dedicated to the torque fluctuation absorbing mechanism, the number of parts can be reduced, and the overall length can be designed to be short, so that the compressor can be downsized. Further, since the permanent magnet is located outside the shaft seal 10, the compressor lubricating oil is not applied. Therefore, the iron powder contained in the lubricating oil is less likely to adhere to the magnet surface and cause a contact accident. Further, since it is located away from the discharge end surface where the temperature tends to rise due to the compression heat, it is possible to use a permanent magnet that is weak against high temperature or an adhesive for fixing the magnet.

Next, a third embodiment of the present invention based on claim 4 will be described with reference to FIG. Note that this embodiment is different from the first embodiment only in the structure of the torque fluctuation absorbing mechanism, and is the same in other respects. Therefore, only the torque fluctuation absorbing mechanism will be described.

FIG. 7 is a side sectional view of the torque fluctuation absorbing mechanism of the third embodiment. The absorption mechanism casing 31 is fixed to the screw compressor body via the end plate 12. The rotor 35 is fixed to the discharge side end 13b of the male rotor shaft, and the stator 36 is fixed to the absorption mechanism casing 31. Their relative positions are axially offset by a certain dimension rather than facing each other as in the first embodiment.

By displacing the rotor 35 and the stator 36 in the axial direction, the torque fluctuation absorbing mechanism of this embodiment produces torque fluctuations in the same manner as in the first embodiment, and at the same time, the axial vibration force is also applied. Can be generated. The magnitude of the axial excitation force can be adjusted by the axial displacement of the rotor 35 and the stator 36. The shifting direction may be opposite to that in FIG. 7 due to the relationship between the torque fluctuation and the axial exciting force. Further, the phase of the torque fluctuation and the axial excitation force can be adjusted by the fixed angle of both the rotor 35 and the stator 36.

According to this embodiment, in addition to the torque fluctuation generated by the screw compressor, axial vibration can be canceled by the torque fluctuation absorbing mechanism. Therefore, it is possible to realize a screw compressor with less vibration noise.

Next, a fourth embodiment of the present invention will be described with reference to FIG. Note that this embodiment is different from the first embodiment only in the structure of the torque fluctuation absorbing mechanism, and is the same in other respects. Therefore, only the torque fluctuation absorbing mechanism will be described.

FIG. 8 is a side sectional view of the torque fluctuation absorbing mechanism of the fourth embodiment. The absorption mechanism casing 41 is fixed to the screw compressor body via the end plate 12. The rotor 45 is fixed to the end surface of the discharge side end 13b of the male rotor shaft via a disc 42, and the stator 46 is axially opposed to the rotor 45 and fixed to the inside of the end surface of the absorption mechanism casing 41.

By making the rotor 45 and the stator 46 face each other in the axial direction, the torque fluctuation absorbing mechanism of this embodiment generates torque fluctuation in the same manner as in the first embodiment, and at the same time,
Axial excitation force can also be generated. Particularly, the axial exciting force can be set to a value larger than that in the third embodiment from the direction in which the magnets face each other.

According to this embodiment, when the axial vibration generated by the screw compressor is larger than the torque fluctuation, it is possible to form a torque fluctuation absorbing mechanism for generating an appropriate canceling force for both. In addition, the axially short design is possible, and it is easy to miniaturize.

A torque fluctuation absorbing mechanism according to this embodiment and FIG.
Both the torque fluctuation and the axial oscillating force may be canceled by combining the torque fluctuation absorbing mechanism according to the second embodiment shown in FIG.

Next, a fifth embodiment of the present invention will be described with reference to FIG. The present embodiment is different from the second embodiment only in the structure of the torque fluctuation absorbing mechanism, and is the same in other respects. Therefore, only the torque fluctuation absorbing mechanism will be described.

The rotor 55 is fixed to the inner end face of the pulley 51 fixed to the male rotor shaft, and the stator 56 is fixed to the outside of the end face of the suction side casing 52 facing the rotor 55 in the axial direction.

By making the rotor 55 and the stator 56 face each other in the axial direction, the torque fluctuation absorbing mechanism of this embodiment produces torque fluctuations in the same manner as in the second embodiment, and at the same time,
Axial excitation force can also be generated. Particularly, the axial exciting force can be set to a value larger than that in the second embodiment from the direction in which the magnets face each other. Therefore, when the axial vibration generated by the screw compressor is larger than the torque fluctuation, it is possible to form a torque fluctuation absorbing mechanism that generates an appropriate canceling force for both. In addition, the axially short design is possible, and it is easy to miniaturize.

This embodiment has the following effects. Since the suction side casing 52 and the pulley 51 are diverted, it is possible to reduce the number of parts without adding a casing and a disk dedicated to the torque fluctuation absorbing mechanism as in the fourth embodiment shown in FIG.
Also, the overall length is designed to be short, and the compressor can be downsized. Furthermore, since the permanent magnet is outside the shaft seal 10 and the compressor lubricating oil is not applied, it is less likely that iron powder contained in the lubricating oil will adhere to the magnet surface and cause a contact accident. Furthermore, since it is located away from the discharge end surface where the temperature easily rises due to the compression heat, it is possible to use a magnet that is weak against high temperature or an adhesive for fixing the magnet.

Next, a sixth embodiment of the present invention based on claim 4 will be described with reference to FIG. The description of the items in this embodiment that are common to the first embodiment will be omitted.

FIG. 10 is a side sectional view of the screw compressor body according to this embodiment. The torque fluctuation absorbing mechanism 61 is provided on the discharge side of the female rotor shaft 63 that is integral with the female screw rotor 2. The rotor 65 is composed of a permanent magnet and is bonded to the female rotor shaft 63. A stator 66 composed of a winding is fixed to the inner surface of the absorption mechanism casing 64 so as to face it.
The end of the winding 66 is drawn out as an output line 67.
The absorption mechanism casing 64 is fixed to the screw compressor body via the end plate 12.

The torque fluctuation absorbing mechanism of this embodiment functions as a generator, and the generated torque is negative, that is, braking is seen from the side of the screw compressor. The fluctuation component of the generated torque has the same fluctuation torque, amplitude, and frequency in the female screw rotor 2 generated by the screw compressor main body,
Make sure the phases are reversed.

The present embodiment operates as follows. Similar to the first embodiment, the torque fluctuation of the screw compressor main body is canceled by the torque fluctuation absorbing mechanism 61, which has the effect of reducing the generation of vibration noise. Further, the torque transmitted from the male screw rotor to the female screw rotor can always be maintained at a certain value or more. Since the torque fluctuation absorbing mechanism is also a generator, the generated electric energy is repelled from the output line 67 to the outside of the main body. After that, it may simply be consumed as heat, or an energy circulation system may be formed which is returned to the power source via the control device.

In addition to the effect of the first embodiment, this embodiment has the effect of suppressing tooth surface separation vibration because the transmission torque can be maintained at a substantially constant positive value. Here, the tooth surface separation vibration means that the torque applied to the female screw rotor becomes negative due to the gas pressure condition, and the tooth surface of the male screw rotor pushes the tooth surface of the female screw rotor to transmit the torque. Vibration in which the rotor runs ahead and the tooth surfaces repeatedly separate and collide. Tooth surface separation vibration is larger than normal vibration because it includes collision, and prevention of this is an important issue.

Next, a seventh embodiment of the present invention will be described with reference to FIG. The description of the items in this embodiment that are common to the first embodiment will be omitted.

FIG. 11 is a side sectional view of the screw compressor body according to this embodiment.

The electric motor 72 is directly connected to the suction side of the screw compressor main body 70, and the casings 3a and 73 are connected to each other with the suction side casing 79 interposed therebetween. The electric motor stator 78 is fixed to the inner surface of the electric motor casing 73 and mainly includes windings. The electric motor rotor 77 is fixed to the male rotor shaft 74 with the electric motor rotor 77 facing each other with a gap.

The torque fluctuation absorbing mechanism 71 is provided between the screw compressor body 70 and the electric motor 72, and is incorporated in the suction side casing 79. The rotor 75 is composed of a permanent magnet and is bonded to the male rotor shaft 74. The permanent magnet stator 76 is fixed to the inner surface of the suction side casing 79 so as to face it.

This embodiment operates as follows. Electric motor 7
The output of 2 directly drives the male rotor shaft 74 to operate the screw compressor. Although the output torque of the electric motor 72 is substantially constant, the torque fluctuation absorbing mechanism 71 acts to cancel the torque fluctuation of the screw compressor body and reduce the generation of vibration noise.

In addition to the effects of the first embodiment, this embodiment can be downsized as a whole by directly connecting the electric motor to the main body. Since the belt is no longer needed, it is no longer necessary to inspect or replace the belt.

In this embodiment, the rotating shaft of the electric motor 72 is used by extending the male rotor shaft 74 of the screw compressor body 70. However, there is a case where the cantilever length is long and vibration, strength, etc. become a problem.

The eighth embodiment of the present invention shown in FIG. 12 is an improvement over the above-mentioned problems.
Is a rotating shaft independent of the male rotor shaft 74, and the rotating shaft 80 is supported by bearings 81 and 82 in the electric motor,
The rotating shaft 80 of the electric motor 72 and the male rotor shaft 74 are connected by a shaft joint 83. In this case, the rotor 75 and the stator 76 of the torque fluctuation absorbing mechanism are the shaft coupling 83.
It is installed closer to the screw compressor body. This is because the shaft coupling is soft in the rotational direction and the vibration force at the mesh frequency cannot be transmitted because the frequency is too high.

[0056]

As described above, according to the present invention, a screw compressor with a simple structure that cancels the exciting force due to the torque fluctuation generated by the change of the internal pressure distribution and has less vibration and noise is realized. be able to.

[Brief description of drawings]

FIG. 1 is a side sectional view of a first embodiment of the present invention.

FIG. 2 is a front view of an embodiment of a torque fluctuation absorbing mechanism.

FIG. 3 is a side view of an embodiment of a torque fluctuation absorbing mechanism.

FIG. 4 is a torque characteristic of a torque fluctuation absorbing mechanism.

FIG. 5 is an example of an annular permanent magnet.

FIG. 6 is a side sectional view of a second embodiment of the present invention.

FIG. 7 is a side sectional view of a torque fluctuation absorbing mechanism according to a third embodiment of the present invention.

FIG. 8 is a side sectional view of a torque fluctuation absorbing mechanism according to a fourth embodiment of the present invention.

FIG. 9 is a side sectional view of a torque fluctuation absorbing mechanism according to a fifth embodiment of the present invention.

FIG. 10 is a side sectional view of a sixth embodiment of the present invention.

FIG. 11 is a side sectional view of a seventh embodiment of the present invention.

FIG. 12 is a side sectional view of an eighth embodiment of the present invention.

[Explanation of symbols]

1 ... Male screw rotor, 2 ... Female screw rotor, 3
... Casing, 3a ... Main casing, 3b ... Suction side casing, 3c ... Discharge side casing, 4a, 4b, 4
c, 4d ... Bearing, 5 ... Bore, 7 ... Suction port, 8 ... Discharge port,
11 ... Torque fluctuation absorbing mechanism, 12 ... End plate, 1
3a ... suction side of male rotor shaft, 13b ... discharge side of male rotor shaft, 14 ... absorption mechanism casing, 15 ... rotor, 16 ...
Stator, 17 ... Fixing bolt, 18 ... Oblong hole, 19 ... Rotor base, 20 ... End cover, 21 ... Torque fluctuation absorbing mechanism,
23 ... suction side casing, 24 ... suction side of rotor shaft, 2
5 ... Rotor, 26 ... Stator, 31 ... Absorption mechanism casing, 35 ... Rotor, 36 ... Stator, 41 ... Absorption mechanism casing, 42 ... Disk, 45 ... Rotor, 46 ... Stator, 5
1 ... pulley, 52 ... suction side casing, 55 ... rotor,
56 ... Stator, 61 ... Torque fluctuation absorbing mechanism, 63 ... Female rotor shaft, 64 ... Absorption mechanism casing, 65 ... Rotor, 6
6 ... Stator, 70 ... Screw compressor main body, 71 ... Torque fluctuation absorbing mechanism, 72 ... Electric motor, 73 ... Electric motor casing, 74 ... Male rotor shaft, 75 ... Rotor, 76 ... Stator,
77 ... Electric motor rotor, 78 ... Electric motor stator, 79 ... Suction side casing, 81, 82 ... Bearings, 83 ... Shaft coupling.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Kamiya 390 Muramatsu, Shimizu City, Shizuoka Prefecture Hitachi Ltd. Shimizu Plant

Claims (5)

[Claims] 1. A male / female 2 that rotates synchronously by engaging screw teeth that are axially parallel to each other and have opposite twist directions.
Screw compression having one screw rotor and a casing for accommodating the two screw rotors through a minute gap, and having a casing in which an intake port is formed on one end surface of the bore and a discharge port is formed on the other end surface In the machine, it has a rotor and a stator that exert forces on each other, and the torque required to rotate the rotor with respect to the stator has a torque fluctuation mechanism having a function of cyclically changing with respect to the rotation angle. The mechanism is provided coaxially with at least one of the male and female screw rotors, the rotor is fixed to the screw rotor shaft, the stator is fixed to the fixed side structural member, and the period of torque fluctuation is meshed with the screw rotor. A screw compressor characterized by matching the cycle. 2. The torque fluctuation mechanism according to claim 1, wherein the torque fluctuation mechanism includes a rotor having a permanent magnet and a stator, and creates a torque fluctuation in which positive and negative are alternately repeated by an attractive force and a repulsive force of the permanent magnets. Screw compressor to do. 3. The screw compressor according to claim 1, wherein the torque fluctuation mechanism is a generator. 4. The screw compressor according to claim 1 or 2, wherein the torque fluctuation absorbing mechanism has, in addition to torque fluctuation in the rotational direction, an axial vibration force synchronized with the torque fluctuation. 5. The rotor and the stator of the torque fluctuation absorbing mechanism according to claim 2, wherein the rotor has a number of magnetic poles twice as many as the number of teeth of the screw rotor to which the rotor is fixed, and the magnetic poles extend along the circumference. The S compressor and the N pole are alternately arranged.