JPH11336679A - Screw compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve performance and reliability by providing a radial displacement means for displacing the rotational center position of a screw rotor to a bore face so as to compensate displacement caused by gas pressure and displacement caused by thermal deformation and to maintain a clearance around an operating chamber particularly in a high pressure state into an appropriate range. SOLUTION: When a male rotor 1 and a female rotor 2 in a screw compressor are rotatory-driven, gas sucked from a discharge opening 7 is compressed and discharged from a discharge opening 8. At this time, the internal pressure of an operating chamber 4 in discharge action becomes highest, and gas load summing up the total pressure of the operating chamber 4 including this internal pressure acts upon both rotors 1, 2 approximately in the opposite directions 11, 12 to the discharge opening 8 from the axial view so as to cause the flexural deformation of the respective rotors 1, 2. A cylinder 25 into which the discharge pressure of the compressor is led is therefore provided, and its piston rod 26 is delivered to turn a nut 22. A column 23 is therefore screwed forward to generate load 17 so as to offset the deformation in the direction of an arrow mark 12 of the female rotor 2 particularly deformed large.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw compressor, which compensates for a gas load of a compressed gas and a displacement of a screw rotor (hereinafter abbreviated as a rotor) due to a thermal deformation of a casing. The present invention relates to a structure suitable for achieving both high efficiency and high reliability by appropriately maintaining the clearance between the bore and the bore surface.

[0002]

2. Description of the Related Art Screw compressors are widely used as refrigerant compressors for refrigeration and air conditioning and general-purpose air compressors because of their high performance and miniaturization. However, in the social situation, as with general industrial machines, the demand for energy saving has been strengthened for screw compressors as well as general industrial machines for the purpose of preserving the global environment, and further improvements in performance have been demanded. On the other hand, screw compressors play an important role at each installation site, and it is naturally considered that high reliability is ensured.

[0003] The compression principle of a screw compressor will be briefly described. The tooth space of the rotor is surrounded by the other screw teeth and the bore inner surface surrounding the rotor to form a substantially closed space called a working chamber. The reason why the space is not completely closed here is that, in order to rotate the rotor smoothly, the outer periphery of the rotor and the inner peripheral surface of the bore, the end surface of the rotor and the end surface of the bore, and a small clearance between the rotors are provided.

The smaller these clearances are, the better the seal between the working chambers is, the less the internal leakage from the working chamber on the high pressure side to the working chamber on the low pressure side, and the energy efficiency is improved. However,
If the clearance is too small, the possibility of unexpected contact increases and reliability is impaired. In the case of contact, energy loss increases due to friction and vibration noise also increases. In the worst case, the contact surface is welded to the metal and the compressor may be damaged. Therefore, it is desirable that the clearance be appropriately managed in order to secure a necessary minimum amount.

[0005] When the rotor is rotated, a working chamber is generated at the suction end, and the inner volume increases while moving in the axial direction. Thereafter, the inner volume starts to decrease and the working chamber disappears at the discharge end. The working chamber communicates with a suction port formed in the bore during the expansion of the internal volume, and sucks the compressed gas therefrom. When the working chamber volume is almost maximum, the working chamber is deviated from the contour of the suction port by rotation and closes to the suction port. The compressed gas trapped inside by the subsequent reduction of the working chamber volume is compressed, and the internal pressure gradually increases. When the working chamber moves to a position where the discharge port is located, the working chamber opens to the discharge port, and the compressed gas is discharged therefrom.

The working chamber after the start of discharge is in a high internal pressure state substantially equal to the discharge pressure. The pressure acts on the tooth surface of the rotor, and the rotor is elastically deformed mainly by deflection under the gas load. In addition, since the bearing that supports the rotor also supports a large load, the center of rotation slightly deviates from the position at rest regardless of the type of the bearing.

For example, when the rotor section near the discharge end is viewed as shown in FIG. 2, both the gas load 11 on the male rotor 1 and the gas load 12 on the female rotor 2 act substantially in the direction opposite to the discharge port 8. This is because the highest pressure acts on each rotor surface facing the working chamber 4 during discharge, from which the working chamber pressure decreases in the reverse rotation direction of the rotation directions 13 and 14 of the rotor. The gas load is the result of integration over the projected area of, and a force acts in the direction from the high-pressure working chamber to the low-pressure working chamber. Due to the gas loads 11 and 12, the rotor bends, the bearings are deformed, and the rotor is displaced in the load direction. Therefore, the clearance 19 on the discharge port side is enlarged, and the clearance 12 on the opposite side to the discharge port is increased.
Shrinks. Further, since the female rotor 2 having a small second moment of area is more easily deformed than the male rotor 1, the amount of change in the clearance is large.

Looking at the gas pressure distribution in the axial direction, since the working chamber with a high pressure is near the discharge end, the equivalent concentrated load of the gas load is near the discharge end even in the section where the screw teeth are formed. Therefore, most of this load is shared by the discharge side bearing, and the share of the suction side bearing is small. Strictly speaking, the gas load fluctuates periodically at the meshing frequency, but the fluctuation is small compared to the time-averaged steady state, and is omitted, and here, the steady state is meant.

The effect of the increase in internal leakage due to the expansion of the clearance on the performance degradation is not uniform throughout the rotor, and the greater the pressure difference between the two sides of the clearance, the greater the leakage and the more significant the performance degradation. Normally, the highest pressure is in the working chamber 4 during discharge, which is in communication with the lowest working pressure suction chamber on the back side of the rotor through the inter-rotor clearance. Therefore, the increase in the clearance between the rotors connected to the working chamber 4 during discharge has the greatest effect on the performance degradation, and it is highly necessary to maintain an appropriate value.

The axial displacement of the rotor is caused not only by the gas load but also by thermal deformation. Due to the heat generated by the compression of the gas, the temperature near the discharge port of the casing and the discharge side of the rotor becomes high. Since the rotor is rotating, the temperature is averaged in the direction of rotation, but the casing has a biased temperature distribution and undergoes complicated thermal deformation such that the bore has a bow shape. Therefore, the positional relationship between the bearing housing and the bore surface is different between the stationary state and the operation state in which the whole is under uniform temperature conditions at room temperature.

The following is known as a method for ensuring a clearance and preventing rotor contact in consideration of the above-described deformation due to gas load and thermal deformation. Japanese Patent Application Laid-Open No. 54-64716 discloses a method in which the center of rotation at rest is shifted from the center of the bore by taking into account deformation. Also, Japanese Patent Application Laid-Open No. 5-231362 discloses a method in which a certain distribution is provided in the gap between the rotor and the bore surface by taking a deformation. In these two known examples, means for preventing contact due to reduction of the clearance are described, but no measures are taken for countermeasures against performance degradation due to expansion of the clearance generated on the opposite side of the rotor.

Japanese Unexamined Patent Publication (Kokai) No. 5-1685 discloses a method in which a rotor and two casings are each formed of three materials having different coefficients of thermal expansion to compensate mainly for thermal deformation in the axial direction. Regarding the radial displacement, there is no mention of the difference between at rest and during operation.

[0013]

In the above-mentioned known example, the setting of the clearance is described under the first condition of avoiding the contact. However, the clearance is increased on the side which is widened by deformation and the amount of internal leakage is increased. No mention is made of any means for preventing performance degradation. Correcting the widening clearance and suppressing the widening of the clearance is an issue to improve the performance of the screw compressor, and if it can be realized, the increase in internal leakage will be suppressed and the operating pressure and discharge temperature will vary. Without
The capacity of the screw compressor can be kept high.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to displace a rotation center position of a rotor with respect to a bore surface formed in a casing, thereby compensating for a displacement due to a gas pressure and a displacement due to a thermal deformation. An object of the present invention is to realize a high-performance and high-reliability screw compressor by maintaining a clearance between bore surfaces in a proper range, particularly around a working chamber in a high pressure state.

[0015]

To achieve the above object, the following means are used.

At least one of the suction means on both sides of the suction and discharge which supports at least one of the two male and female rotors is provided with a radial displacement means. At this time, when one radial displacement means is provided, the greatest effect can be expected if the radial displacement means is provided on the discharge side of the female rotor. The radial displacement means has a function of giving a displacement in accordance with pressure conditions such as suction pressure, discharge pressure or working chamber pressure, or temperature conditions such as discharge gas temperature and a part of the casing temperature, or both.

In order to realize the above means with a simple structure at a low cost, the following means are added.

The radial displacement means is constituted by a support made of a material having a larger coefficient of thermal expansion than the material constituting the casing. For example, when the casing is cast iron, brass or 2
Use 0% nickel steel or the like. The support supports the bearing housing member, which is separate from the casing, from the side substantially opposite to the discharge port side when viewed from the axial direction. further,
A discharge channel is formed around or near the column so that the column can easily conduct heat with the discharge gas.

Here, the "opposite side with the discharge port" refers to a straight line connecting the two rotor rotation centers and a straight line orthogonal to the straight line and passing through each rotor center when viewed from the axial direction. Means the area facing the area including the discharge port and the direction in which at least a part of the radial displacement means supporting the bearing housing member exists on the outline of the area divided into four.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, using FIGS. 1 to 4,
First Embodiment A screw compressor according to a first embodiment of the present invention will be described. FIG. 1 is a sectional view of the screw compressor according to the present embodiment, which is divided at the center axis of the female rotor. FIG. 2 is a cross-sectional view of the rotor, showing the relationship between the direction of the gas load and the position of the discharge port. FIG. 3 is a sectional view of the vicinity of the bearing 6 of FIG. FIG. 4 is a perspective view of an example of the bearing displacement mechanism.

First, the configuration of the first embodiment will be described.

1 and 3, the male rotor 1 and the female rotor 2 are meshed with each other, supported by a suction bearing 5 and a discharge bearing 6, and housed in a bore formed inside the casing 3. A clearance is provided between the bore surface 18 and the rotors 1 and 2 so that the bore surface 18 does not come in contact with the rotor at rest. The outer periphery of the discharge side bearing 6 of the female rotor 2 is fixed to a bearing block 9 which is a bearing housing member, and the bearing block 9 is fixed to the casing 3 via a bearing displacement mechanism 10 which is radial displacement means.

The casing 3 is provided with a suction port 7 and a discharge port 8. Since the gas flow during compression due to the movement of the working chamber is approximately from left to right in FIG. 1, the left direction is called the suction side, and the right direction is called the discharge side. The male rotor 1 is powered by an electric motor or the like, but a power source and a power transmission system are not directly involved in the present invention, and therefore description thereof is omitted.

In FIG. 3, the bearing displacement mechanism 10 is provided at a position indicated by an arrow 17 indicating a load, and the load 17 can act on the bearing block 9. The direction of this load is opposite to the direction 12 of the gas load shown in FIG.
In the direction of.

As shown in FIG. 4, the bearing displacement mechanism 10 has a structure in which a screw jack is moved by a gas pressure cylinder. The nut 22 rotatably provided on the base 21 has bars 24 on both side surfaces, and a female screw provided on the inner surface of the nut 22 and a male screw provided on the outer periphery of the column 23 mesh with each other. The column 23 is restrained from rotating on the base 21. The cylinder 25 is installed at a position where the discharge pressure of the compressor is guided and the rod 26 connected to the internal piston pushes the bar 24.

Hereinafter, the operation and operation of the first embodiment will be described.

By the operation of the compressor, the male rotor 1 and the female rotor 2 rotate 13 and 14 to compress the gas sucked in from the discharge port 7 and discharge it from the discharge port 8 to the outside. At this time, the working chamber 4 during discharge has the highest internal pressure. The gas load obtained by integrating the pressures of all the working chambers including this pressure is substantially opposite to the discharge port 8 when viewed from the axial direction.
Act on. Due to the gas load, the rotor bends, and the bearing elastically deforms around the contact point between the rolling element and the inner and outer rings. The amount of deformation is large for the female rotor 2 having a small moment of inertia and a small bearing. These deformations narrow the gap 20 on the side opposite to the discharge port, and widen the gap 19 on the side of the discharge port.

The discharge pressure gradually increases with the start of operation of the compressor.
5 The internal pressure also rises, the rod 26 is extended, the bar 24 is pushed, and the nut 22 is turned. The column 23 protrudes by the action of the screw, and generates a load 17. The rod 26 depends on the discharge pressure.
Is increased to a sufficient size by leverage and screws, and a load 17 is obtained. The load 17 pushes the bearing block 9 approximately in the direction of the discharge port 8 to cancel the deformation caused by the gas load.

By the above operation, the clearance 20 on the side opposite to the discharge port 20
Both the reduction of the diameter and the expansion of the discharge port side clearance 19 are suppressed,
The clearance can be maintained in an appropriate range. Therefore, the contact accident is prevented because the clearance is not abnormally reduced, and the reliability of the compressor is not impaired. At the same time, the abnormal expansion of the clearance does not occur, so that a decrease in performance due to an increase in internal leakage can be eliminated.

The size of the weight 17 can be adjusted according to the length of the bar 24 and the pitch of the screw between the column and the nut. In addition, the maximum displacement is defined by a displacement prevention structure (not shown) or a buffer structure that supports the bearing block 9 from the opposite side of the bearing displacement mechanism 10 to prevent an unexpected situation caused by the bearing displacement mechanism giving excessive displacement. Preventive designs are possible.

In this embodiment, since the bearing displacement mechanism 10 is moved by using the discharge pressure, a dedicated power source is not required. Further, since the same gas load as the cause of deformation of the rotor and the bearing is used for the power source, the magnitude of the load is automatically adjusted, and a control device or the like is not required.

In the present embodiment, the amount of thermal deformation is sufficiently smaller than the amount of deflection of the rotor and the amount of deformation of the bearing due to the gas load, and the displacement to be corrected by the bearing displacement mechanism 10 is the former two. The assumption was made. Therefore, if the amount of thermal deformation is of a magnitude that cannot be ignored, arrow 17
Is the direction and magnitude of the thermal deformation as a vector. Therefore, in this case, in order to attach the bearing displacement mechanism 10 in a desired direction, the load direction 17 is changed to the discharge port 8 as shown in FIG.
It doesn't always turn.

Although the casing 3 is shown as an integral structure in FIG. 1, even if the casing 3 is divided for manufacturing or other reasons, it does not affect the essence of the present invention.

In the present embodiment, the bearing displacement means 10
Provided on the discharge side of the female rotor 2 is a portion where the influence of the deformation due to the gas load assumed here is the largest,
This is because the effect is greatest. By adding the present displacement means to other bearings, it becomes possible to manage the clearance more thoroughly. Further, if conditions such as the structure of the compressor, the gas load, and the temperature distribution are different, a greater effect may be expected when the displacement means 10 is provided on another bearing.

In the present embodiment, a description has been given of a screw compressor having a structure in which the power input to the male rotor 1 is transmitted by contact between the tooth surfaces of the rotor. In the screw compressor, there is also an oil-free type in which rotation is transmitted by synchronous gears provided at shaft ends of both rotors, and the rotors are not in contact with each other. Since the present invention is not directly related to the rotation transmission method, the same effects can be expected for both types of screw compressors, and similar effects can be expected.

In the present embodiment, the suction-side bearing 5 is shown as an example of a ball bearing, and the discharge-side bearing 6 is shown as an example of a combined bearing composed of a cylindrical roller bearing and an angular ball bearing. However, the type of bearing does not directly affect the essence of the present invention, and other types of bearings may be used.

2. Next, a screw compressor according to a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, only the configuration, operation, and effect different from those of the first embodiment will be described, and the common contents will be omitted.

The bearing displacement mechanism 10, which is a means for radially displacing the bearing, comprises a hydraulic mechanism comprising a piston 33 and a cylinder 34 and a force multiplier 31 connected by a hydraulic pipe 32. The cylinder 34 and the power multiplier cylinder 35 are connected by a hydraulic pipe 32. The power multiplier cylinder 35 is composed of a large-diameter and small-diameter two-stage cylinder, and a stepped piston 36 that fits therein is provided. The small-diameter cylinder portion is filled with hydraulic oil that communicates with the cylinder 34, and the suction pressure 37 of the compressor is guided to the left side 37 of the large-diameter cylinder and the discharge pressure is guided to the right side 38 of the large-diameter cylinder by a pipeline.

When the difference between the suction pressure and the discharge pressure is increased by the operation of the compressor, the stepped piston 36 moves to the left and pushes up the piston 33 via the hydraulic oil. The cross-sectional area of the large-diameter piston of the power doubler 31 is S1, and the cross-sectional area of the small-diameter piston is S.
2. Assuming that the cross-sectional area of the piston 33 is S3, the force F generated by the bearing displacement mechanism 10 becomes the value of Expression 1. Therefore, by designing S1 and S3 to be large and S2 to be small, a force larger than the bearing load can be output.

[0040]

(Equation 1)

According to the present embodiment, the size of the bearing displacement mechanism 10 can be reduced, and the addition of a plurality of bearing displacement mechanisms becomes easy.
Since the position of the power multiplier 31 can be set apart from the bearing displacement mechanism 10, the degree of freedom in designing the compressor is increased. In addition, since it is composed of only a simple sliding mechanism that does not use screws, there are few unstable factors of movement due to friction, and the reliability is high. further,
Changes in the discharge pressure are quickly converted to bearing displacement,
It has good followability to the discharge pressure, and is suitable for applications in which the discharge pressure changes drastically and compressors that frequently start and stop.

The power multiplier 31 in the present embodiment does not need to be provided independently. A power multiplier cylinder 35 is formed in a part of the casing 3, and the hydraulic pipe 32 can be constituted by a hole formed inside the casing 3. . The hydraulic oil for transmitting hydraulic pressure may also be used as lubricating oil for the compressor.

Although a piston ring is provided for sealing between the cylinder and the piston used in this embodiment, a general member or structure may be used.

In this embodiment, the bearing displacement mechanism is driven by hydraulic pressure using the suction and discharge pressures of the compressor itself. However, the same applies when the piston 33 is directly driven by an externally provided hydraulic source. Operation can be expected. In the case of control using external hydraulic pressure, an electronic control device can be used as a controller. In this case, the mechanism becomes complicated, but not only the bearing displacement is given as a simple function of the pressure condition, but also other conditions such as the temperature condition can be added to the input as a judgment material. Complicated control is possible.

3. Further, a screw compressor according to a third embodiment of the present invention will be described with reference to FIG. In the third embodiment, only configurations, operations, and effects different from those of the first and second embodiments will be described, and common contents will be omitted.

The bearing displacement mechanism 39, which is a means for radially displacing the bearing, is made of a material having a larger coefficient of thermal expansion than the casing 3, and is provided with a number of slit-shaped holes for the purpose of increasing the surface area. The discharge port 8 extends from the working chamber to the bearing chamber 4 in the casing 3.
0 and a gas outlet is provided in the upper part of the bearing chamber.

The operation of the compressor increases the discharge pressure and the discharge temperature. The discharge gas flows from the discharge port 8 to the bearing chamber 40.
And passes through the periphery of the bearing displacement mechanism 39 to be sent out. The bearing displacement mechanism 39 receives heat from the discharged gas, rises in temperature, and thermally expands. Since the expansion amount is larger than the other members, the bearing block 9 is displaced downward in the drawing.

In the present embodiment, since the bearing displacement mechanism has a simple structure in which no moving parts are used, friction wear and failure are unlikely to occur. Further, it can be implemented relatively inexpensively.

In this embodiment, the bearing chamber 40 is used for the flow path of the discharge gas for simplifying the structure. From the viewpoint of bearing lubrication and bearing cooling, it is advantageous to separate the bearing chamber from the discharge gas flow path. When that point is emphasized, the discharge gas flow path and the bearing chamber may be separated. Does not affect the nature of

4. Further, a screw compressor according to a fourth embodiment of the present invention will be described with reference to FIG. The fourth
In this embodiment, only configurations, operations, and effects different from those of the first to third embodiments will be described, and common contents will be omitted.

A piezoelectric element which expands and contracts when a voltage is applied to the bearing displacement mechanism 10 from the outside is used. The external voltage is controlled by an electronic controller, and the voltage is determined based on the pressure condition and temperature condition obtained by the sensor.

According to the present embodiment, the system becomes complicated,
Although a new component member is required, complicated control including non-linearity and case classification can be performed, and the response speed is extremely fast, and it is possible to follow fast changes in pressure and temperature conditions.
Depending on the capability of the control system, it is also possible to feedback-control the displacement to be applied to the bearing while actually measuring the clearance with a sensor.

5. Further, an auxiliary support structure of the bearing block 9 according to the screw compressor of each embodiment of the present invention will be described with reference to FIGS.

The bearing block 9 has the desired displacement direction 15
Is desirably displaced without hindrance by the bearing displacement mechanism 10, but it is desirable that it be rigid in the restraining direction 16 which is a direction perpendicular to the direction. Further, the displacement amount in the displacement direction 15 is usually as small as about 10 to 50 μm, and a linear bearing or a sliding structure generally used as a mechanical component is not suitable. Therefore, a support mechanism that supports the bearing block from both sides and allows only the intended displacement direction by its own shear elastic deformation is desirable.

FIG. 7 shows an example in which a laminated body of a thin rubber 42 and a metal plate 43 is used for the auxiliary support member 41. The rigidity is high because the rubber 42 is thin and the amount of deformation is extremely small. Since the rubber layer of the auxiliary support member has a slight vibration blocking effect, an effect of suppressing external propagation of rotor vibration can be expected. Further, since FIG. 7 is a schematic diagram, the thickness of the auxiliary support member 41 is expressed to be thicker than the actual body for easy understanding.

FIG. 8 shows an example in which a comb-shaped metal is used for the auxiliary support member 44, in which a rectangular parallelepiped metal block is provided with a large number of thin slit grooves. In this method, the rigidity is high in all directions other than the target displacement direction 15, and since there is no careless displacement of the axis, the reliability is high. Further, compared to the method shown in FIG. 7, since a rubber material is not used, the method is widely used for long-term reliability and use in a high temperature environment.

[0057]

According to the present invention, the clearance between the rotors and between the outer periphery of the rotor and the bore surface generated by the deformation of the bearing and the rotor due to the gas pressure and the thermal deformation of each member caused by the heat of compression. The amount of deformation can be compensated and the clearance can be maintained in an appropriate range. Therefore, the clearance becomes excessive, the internal leakage increases and the performance is reduced, or the clearance becomes too small to prevent a contact accident from occurring, and a high-performance and highly reliable screw compressor can be realized. .

[Brief description of the drawings]

FIG. 1 is a sectional view of a screw compressor according to a first embodiment.

FIG. 2 is a cross-sectional view perpendicular to the axis of the screw compressor having the conventional structure of the present invention.

FIG. 3 is a schematic view of the vicinity of an ejection port side end in the first embodiment.

FIG. 4 is a perspective view of an example of a weight adding unit according to the first embodiment.

FIG. 5 is a schematic diagram of an example of a weight adding unit according to the second embodiment.

FIG. 6 is a schematic diagram of an example of a weight adding unit according to a third embodiment.

FIG. 7 is a schematic view of a first example of an auxiliary support structure for a bearing block common to the embodiments.

FIG. 8 is a schematic view of a second example of an auxiliary support structure for a bearing block common to the embodiments.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Male rotor, 2 ... Female rotor, 3 ... Casing, 4 ... Working chamber during discharge, 5 ... Suction side bearing, 6 ... Discharge side bearing, 7 ...
Suction port, 8 discharge port, 9 bearing block, 10 bearing displacement mechanism, 11 gas load direction on male rotor, 12
Direction of gas load on the female rotor, 13: rotational direction (male rotor), 14: rotational direction (female rotor), 15: displacement direction, 16: restraint direction, 17: load by the bearing displacement mechanism,
18: bore surface, 19: discharge port side clearance, 20: non-discharge port side clearance, 21 ... base, 22 ... nut, 23 ... column, 24 ... bar, 25 ... cylinder, 26 ... rod, 31
... force multiplier, 32 ... hydraulic pipe, 33 ... piston, 34 ... cylinder, 35 ... force multiplier cylinder, 36 ... stepped piston, 37 ... suction pressure chamber, 38 ... discharge pressure chamber, 39 ... thermal expansion type bearing Displacement mechanism, 40: bearing chamber, 41: auxiliary support, 42: rubber, 43: metal plate, 44: auxiliary support.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigekazu Nozawa 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture Inside Air Conditioning Systems Division, Hitachi, Ltd. Inside the mechanical laboratory

Claims (1)

[Claims] The present invention comprises two male and female screw rotors, which are housed in a bore formed in a casing, and have a function of sucking, compressing and discharging compressed gas by rotating while meshing with each other. In a screw compressor having a structure in which two screw rotors are respectively supported by shafts extending to both sides on the suction side and the discharge side beyond the section where the screw teeth are formed, at least one of the two male and female screw rotors At least one of the suction side and the discharge side supporting the one side is provided with a radial displacement means, and the displacement means has a function of giving a displacement according to at least one of a pressure condition and a temperature condition. A screw compressor, characterized in that: