JP2004340060A - Two-screw type compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a two-screw type compressor which can reduce vibration and noise and can save power to be consumed, by mostly removing thrust load and rotating torque acting on a double-threaded screw. <P>SOLUTION: In the two-screw type compressor according to the invention, gas is introduced into a space between thread grooves so as to be conveyed, compressed and discharged continuously by rotation of a driving screw 6 and the follower screw 7. A pair of screw slots 21, 22 having the same configurations are formed in the peripheral side surface of the follower screw 7 symmetrical with the follower screw 7 at the positions with respect to a point. The projected area of the range surrounded by two curves of the addendum curve of the driving screw 6 and the addendum curve of the follower screw 7, in the plane of projection of the range where the follower screw 7 and the driving screw 6 engage, is equal to that of the screw slot 21, 22 exposed to an end face of the follower screw 7 on the discharge side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a twin-screw compressor that is used in, for example, refrigeration and air conditioning equipment, and that sucks and compresses low-pressure gas and discharges high-pressure gas.
[0002]
[Prior art]
Conventional twin-screw compressors are generally known by the name of screw compressors. As an example, in a screw compressor disclosed in Patent Document 1, for example, the ratio of the number of threads between a driving screw and a driven screw is 1: 2, and the diameter of the addendum circle of both screws is the driven screw having the larger number of threads. And the tooth profile of both screws is a trochoid-based tooth profile conjugate to each other, so that both screws and the casing that contains them theoretically completely close and maximize the volume The screw groove space is defined, and a discharge port is provided between the tip circle and the root circle of the driven screw on the inner end surface of the casing.
[0003]
[Patent Document 1]
JP 2001-20885 A
[Problems to be solved by the invention]
However, in the above-described conventional two-shaft screw compressor, although the sealing performance of the single screw and the double screw is considered, the width and inclination of the tooth portion and the screw groove of each screw are not balanced. Therefore, a thrust load and a rotating torque are generated in the double thread during the compression process, so that there is a problem that vibration and noise are large, power consumption is large, and an expensive thrust bearing must be used.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems. By reducing the thrust load and the rotational torque acting on the double thread screw to almost zero, vibration and noise can be reduced and power consumption can be reduced. It is an object of the present invention to obtain a twin-screw type compressor capable of saving energy.
[0006]
[Means for Solving the Problems]
In the twin-screw compressor according to the present invention, the rotation of the single-start screw and the double-start screw takes in a gas into the compression chamber, and conveys, compresses, and discharges the gas. In the double thread, a thread groove is formed in the same shape at a position symmetrical with respect to the peripheral side surface by 180 degrees, and the tip of the single thread is projected on a projection surface in a range where the double thread and the single thread mesh with each other. The projected area of the range surrounded by the curve and the tooth curve of the double thread is equal to the projected area of the screw groove exposed on the end face of the double thread on the discharge side.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view of a twin-screw compressor according to Embodiment 1 of the present invention, and FIG. 2 is a sectional view taken along line AA and BB of FIG.
In this twin-screw screw compressor, an electric motor 4 which is driving means housed in a second container portion 1B below a closed container 1 which is a low-pressure shell, and a shaft 6a connected to a shaft 4a of the electric motor 4. And a single drive screw 6 having trochoidal teeth 6b and a driven screw 6 having two trochoidal teeth 7b. It has. The outer diameters of the driving screw 6 and the driven screw 7 are the same, and the length from the root to the tip is the same.
The drive screw 6 and the driven screw 7 are housed in the first container portion 1A at the upper part of the closed container 1, and the hatching in FIG. 3 is provided between the inner wall surface of the second container portion 1B and the screws 6, 7. The thread space 17 shown in FIG. In FIG. 3, the thick line of the thread groove space 17 indicates the screw groove space 17 on the front side of the drawing, and the dotted line of the screw groove space 17 indicates the screw groove space 17 on the back side of the drawing. In the screw groove space 17, a plurality of drive screws 6 and driven screws 7 are continuously formed along the axial direction by trochoidal teeth 6b, 7b having no gap.
In consideration of the strength and workability of the tooth tips of the driving screw 6 and the driven screw 7, it is desirable to slightly round the tooth tips.
[0008]
Further, the twin-screw compressor includes a first bearing 9 and a second bearing 8 that rotatably support the driving screw 6, a first seal 13 provided near the first bearing 9, and a second bearing 9. A second seal 12 provided near the second bearing 8, a first bearing 11 and a second bearing 10 for rotatably supporting the driven screw 7, and a second seal 12 provided near the first bearing 11. The second seal 14 provided near the first seal 15 and the second bearing 10, and the drive screw 6 and the driven screw 6 directly above the first bearing 11 of the drive screw 6 first bearing 9 and the driven screw 7. A timing gear 27 for synchronously driving the screw 7 is provided.
The first container section 1A and the second container section 1B have independent closed spaces. A suction port 2 for sucking an external gas into the first container 1A is formed at a lower portion of the first container 1A, and a first container 1 is provided at an upper portion of the first container 1A. A discharge port 3 from which the gas in 1A is discharged to the outside is formed.
[0009]
The shaft 6a of the drive screw 6 is connected to the shaft 4a of the electric motor 4, and a first lubricating oil passage 28 is formed along the center axis of the shaft 6a and the shaft 4a. The first lubricating oil passage 28 communicates with a lubricating oil storage unit 29 provided at the lower part of the closed container 1. A pump 34 for feeding the lubricating oil in the lubricating oil storage unit 29 to the first lubricating oil passage 28 is provided in the lubricating oil storage unit 29. The first lubricating oil passage 28 has an intermediate portion where the first branch passage 30 is branched. The first branch passage 30 communicates with the first seal 13.
A space that communicates with the second bearing 8 and the second seal 12 is formed at the outlet of the first lubricating oil passage 28. The outlet of the first lubricating oil passage 28 communicates with the second lubricating oil passage 32 formed along the central axis of the shaft 7 a of the driven screw 7 via the third lubricating oil passage 31. . In the second lubricating oil passage 32, a space communicating with the second bearing 10 and the second seal 14 is formed. At the lower end of the second lubricating oil passage 32, a second branch passage 33 that is in communication with the first seal 15 is branched.
[0010]
Next, the operation of the above configuration will be described with reference to FIG.
First, when the electric motor 4 is energized, the drive screw 6 which is a single thread rotates in one direction, and the driven screw meshed with the drive screw 6 also rotates in the opposite direction in conjunction therewith. At this time, the rotation speed ratio between the driving screw 6 and the driven screw 7 is 2: 1. By the rotation of the driving screw 6 and the driven screw 7, the gas is guided from the suction port 2 to the screw groove space 17 in the first container 1A (see (1) and (2) suction processes in FIG. 4). .
The gas guided to the closed thread space 17 is moved upward (see the transfer steps (3) and (4) in FIG. 4), and then contracted. When the pressure increases and reaches a specified value, the gas is discharged. The valve 18 is opened, and the gas is discharged from the discharge port 3 to the outside of the first container portion 1A and discharged to a refrigeration cycle (not shown) ((5) compression step in FIG. 4, (6) in FIG. ) Refer to the compression / discharge process). In FIG. 4, the bold line in the compression chamber, which is the screw groove space 17, is the front side of the paper, and the dotted line is the back side of the paper.
[0011]
In this embodiment, the sealed container 1 is a low-pressure shell, and the lubricating oil in the lubricating oil storage unit 29 is driven by the trochoid pump 34 through the first lubricating oil passage 4a to form the first bearing 9 and the second bearing. 8, is supplied to the first seal 13 and the second seal 12. Further, the lubricating oil is continuously supplied to the second bearing 10, the first bearing 11, the second seal 14, and the first seal 15 through the third lubricating oil passage 31 and the second lubricating oil passage 32. . Therefore, the amount of wear of each bearing 8, 9, 10, 11 and each seal 11, 12, 13, 14 is reduced.
[0012]
FIG. 5 is a plan view when the driving screw 6 and the driven screw 7 of FIG. 1 are engaged with each other. The driven screw 7 has a pair of screws of the same shape at 180 ° symmetrical positions on the peripheral side surface. Grooves 21 and 22 are formed.
In FIG. 5, among the intersections of the addendum circle of the tooth portion 6b of the drive screw 6 and the addendum circle of the tooth portion 7b of the driven screw 7, point A is above the paper surface, point C is below the paper surface, and the tooth of the drive screw 6 is shown. The contact point between the base circle of the driven screw 7 and the tip circle of the driven screw 7 is defined as point B, and the contact point of the tip circle of the drive screw 6 and the root circle of the driven screw 7 is defined as point D. Also, at the overlapping point of the tooth tip circle of the driven screw 7 and the curve defining the thread groove spaces 21 and 22, the most advanced positions in the clockwise direction are E1 and E2 points, and the most delayed position in the clockwise direction is the H1 point. And H2 point, the overlap point of the root circle of the driven screw 7 with the curve defining the thread groove spaces 21 and 22, the most advanced positions in the clockwise direction are the F1 and F2 points, and the most delayed positions in the clockwise direction. G1 point and G2 point.
[0013]
FIG. 6 shows a state in which the drive screw 6 as a single thread and the driven screw 7 as a double thread are meshed with each other, and the circle between the tooth tip and the root of the driven screw 7 is set to the B1 point and D1 point of the driven screw 7. FIG. 10 is a view cut at a point I located 180 degrees opposite to the middle point of FIG. In FIG. 6, the tooth A indicates one of the teeth 7b of the driven screw 7, and the tooth B indicates the other tooth 7b of the driven screw 7 which is 180 degrees symmetric.
6, among the intersections of the addendum circle of the drive screw 6 and the addendum circle of the driven screw 7, point A1 is on the right side of the drawing, point C1 is on the left side of the drawing, and the root circle of the driving screw 6 and the driven screw are not shown. The contact point between the tip circle of the driving screw 6 and the root circle of the driven screw 7 is point D1. Note that points A1, B1, C1, and D1 in FIG. 6 are points A, B, C, and D in FIG.
[0014]
In FIG. 5, the projected area of the area ABCD surrounded by the tooth tip arc ABC of the driven screw 7 and the tooth tip ADC ADC of the driving screw 6, and E1, F1, G1, and H1, which are the screw grooves 21 and 22 of the driven screw 7, respectively. The tooth shapes of the driving screw 6 and the driven screw 7 are formed such that the projection areas of the areas surrounded by E2, F2, G2, and H2 are the same. The projected area is the projected area of the thread grooves 21 and 22 exposed on the end face of the driven screw 7 on the ejection side.
Therefore, the gas loads acting on the driven screw 7 in the left-right direction and the vertical direction in the drawing of the driven screw 7 in the first compression chamber 23 or the second compression chamber 24 in FIG. 6 are balanced. Since the compression chambers after the third compression chamber 25 and the fourth compression chamber 26 are surrounded in all directions by the drive screw 6, the driven screw 7, and the first container 1A, the gas load acting on the driven screw 7 Will be balanced. If the load in the vertical direction on the paper of the first compression chamber 23 or the second compression chamber 24 is balanced, the thrust force acting on the driven screw 7 from the first compression chamber 23 or the second compression chamber 24. Becomes zero. If the load in the left-right direction of the paper of the first compression chamber 23 or the second compression chamber 24 is balanced, the rotational direction of the driven screw 7 acting from the first compression chamber 23 or the second compression chamber 24 Is zero, that is, the rotational torque is zero. Therefore, the thrust bearing can be simplified and the electric power of the electric motor 4 of the twin screw compressor can be reduced.
[0015]
In FIG. 5, the position of the discharge valve 18 is provided at a portion of the driven screw 7 on the side where the driving screw 6 and the driven screw 7 start to mesh with each other and between the tooth circle and the root circle of the driven screw 7 so as not to overlap. I have. That is, it is provided at a position between the tooth tip and the root of the driven screw 7 in FIG. 5 and further clockwise than the tooth tip curve AD of the driving screw 6. In addition, on the upper surface of the first container portion 1A which is in contact with the driven screw 6 and the driven screw 7, the driven screw is moved in a clockwise direction from the tooth tip curve AD of the driven screw 6, that is, in a direction away from the driven screw 6. A gap is provided between the addendum circle and the root circle of No. 7. As a result, the discharge pressure can be freely set from a value close to the suction pressure, and the compressed gas can be completely discharged.
[0016]
Also, even if the gas leaks from the first compression chamber 23 during the compression, the gas enters the second compression chamber 24 lower than the pressure in the first compression chamber 23 as shown in FIG. Since the absorption is absorbed, the leakage loss can be reduced, and the low-speed operation can be performed, so that the power consumption can be reduced.
[0017]
Although the driving screw 6 and the driven screw 7 are made of a metal material, they can be manufactured by a grinding machine, a lathe machine or the like. Further, after the rough shapes of the driving screw 6 and the driven screw 7 are created, co-sliding lapping in which the polishing is performed while engaging the driving screw 6 and the driven screw 7 using an abrasive having a particle size of 10 μm or less. By doing so, the driving screw 6 and the driven screw 7 with high accuracy can be manufactured.
[0018]
In the above-described embodiment, the driving screw 6 is used as the single thread and the driven screw 7 is used as the double thread. However, the driven screw may be used as the single thread and the driving screw may be used as the double thread. In this case, the ratio of the driving screw to the driven screw of the rotational speed is 2: 1.
[0019]
Further, in this embodiment, the sealed container 1 is a low-pressure shell, which directly discharges the gas after being conveyed and compressed to the outside, and uses a pump 34 as a refueling means.
On the other hand, in the case of a high-pressure shell that discharges the gas after being conveyed and compressed into the second container portion 1B and then discharges the gas to the outside of the closed container 1, the second container portion containing the electric motor is used. 1B is a discharge pressure, and lubricating oil in the lubricating oil storage unit 29 is supplied to the first bearing 9, the second bearing 8, and the first seal 13 through the first lubricating oil passage 4a by differential pressure lubrication. And the second seal 12. Further, the lubricating oil is continuously supplied to the second bearing 10, the first bearing 11, the second seal 14, and the first seal 15 through the third lubricating oil passage 31 and the second lubricating oil passage 32. Can be. In addition, even in the case of the high-pressure shell, the pump 34 may be installed similarly to the low-pressure shell.
[0020]
Further, the drive screw 6 and the driven screw 7 may be manufactured by resin molding instead of the metal material.
[0021]
The first seal 13 and the second seal 12 provided at both ends of the drive screw 6 and the first seal 15 and the second seal 14 provided at both ends of the driven screw 7 have seals. Any material such as a ring, a labyrinth seal, and a tip seal may be used as long as the amount of leakage can be reduced.
[0022]
【The invention's effect】
As described above, according to the twin-screw compressor according to the present invention, the rotation of the single screw and the double screw takes in the gas into the compression chamber, and continuously transports, compresses, and discharges the gas. In the shaft-screw type compressor, the double-threaded screw is formed with a screw groove of the same shape at a position symmetrical to the peripheral side at 180 degrees. In the above, the projected area of the range surrounded by the two curves of the tip curve of the single thread and the tip curve of the double thread is equal to the projected area of the screw groove exposed on the end face of the double thread on the discharge side. By making the thrust load and rotational torque acting on the double thread substantially zero, vibration and noise can be reduced and power consumption can be reduced.
[Brief description of the drawings]
FIG. 1 is a side sectional view of a twin-screw type compressor according to Embodiment 1 of the present invention.
FIG. 2 is a diagram showing a cross section taken along line AA and a cross section taken along line BB in FIG. 1;
FIG. 3 is a diagram showing a thread groove space generated when the driving screw and the driven screw of FIG. 1 are meshed with each other.
FIG. 4 is an operation diagram of the double thread type compressor of FIG. 1;
FIG. 5 is a plan view when the driving screw and the driven screw of FIG. 1 are in mesh with each other.
FIG. 6 is a developed view after cutting at a predetermined position in a state where the driving screw and the driven screw of FIG. 1 are engaged with each other.
FIG. 7 is a diagram showing a state in which gas leaks from a first compression chamber to a second compression chamber in FIG. 6;
[Explanation of symbols]
REFERENCE SIGNS LIST 1 sealed container, 2 suction port, 3 discharge port, 4 motor (drive means), 6 drive screw (single thread), 7 driven screw (double thread), 8 second bearing, 9 first bearing, 10 second Bearing, 11 first bearing, 12 second seal, 13 first seal, 14 second seal, 15 first seal, 17 screw groove space, 18 discharge valve, 21 screw groove, 22 screw groove, 23 first compression chamber, 24 second compression chamber, 25 third compression chamber, 26 fourth compression chamber, 28 first lubricating oil passage, 31 third lubricating oil passage, 32 second lubricating oil aisle.

Claims (5)

A single-start screw having trochoidal teeth,
A double-threaded screw having a trochoidal tooth portion conjugated with the single-threaded screw and the tooth portion;
An airtight container including a first container portion including the double screw and the single screw and forming a compression chamber that is a plurality of screw groove spaces along the axial direction between the single screw and the double screw;
A first bearing and a second bearing rotatably supporting both ends of the single thread and the double thread;
A first seal and a second seal provided near each of the first bearing and the second bearing to ensure the hermeticity of the first container portion;
By the rotation of the single-thread screw and the double-thread screw, a gas is taken into the compression chamber, and the conveyance, compression, and discharge of the gas are performed in a twin-screw screw compressor.
The double-threaded screw is formed with a thread groove of the same shape at a position symmetrical with respect to the peripheral side surface at 180 degrees. A twin-screw compressor in which a projected area in a range surrounded by two curves of a front curve and a tooth curve of the double thread is equal to a projected area of the screw groove exposed on a discharge-side double thread end face. The hermetic container includes the first container portion, and a second container portion connected to the container portion and containing a driving unit,
One of the single screw and the double screw is a drive screw connected to the driving means and rotated by driving the driving means, and one of the single screw and the double screw is the other of the driving screws. The twin-screw compressor according to claim 1, wherein the driven screw is a driven screw that rotates in conjunction with the rotation. A first lubricating oil passage through which the lubricating oil passes is formed along the axis of the single thread, and a second lubricating oil passage through which the lubricating oil passes along the axis of the double thread, Further, a third lubricating oil passage connecting the second lubricating oil passage and the first lubricating oil passage is provided between the single thread and the double thread, and the first lubricating oil passage is provided. Lubricating oil is supplied to the first bearing, the second bearing, the first seal, and the second seal through the second lubricating oil passage and the third lubricating oil passage. The twin-screw compressor according to any one of claims 1 to 2. The twin-screw compression according to any one of claims 1 to 3, wherein the closed container is a low-pressure shell, and is configured to directly discharge the gas after being conveyed and compressed to the outside of the closed container. Machine. 4. The airtight container according to claim 1, wherein the airtight container is a high-pressure shell, and discharges the gas after being conveyed and compressed into the airtight container, and thereafter discharges the gas to the outside. Twin screw compressor.

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