JP2007146662A - Air compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a compact, simple and inexpensive structure, and to achieve low noise in an air compressor. <P>SOLUTION: The air compressor 100 is provided with a capacity type compressor body 1 for compressing air; and a heat exchanger 10 having a pipe for making the compressed air delivered from a delivery port 2 of the compressor body 1 flow. The heat exchanger 10 is constituted of a plurality of pipes 14-16 connected in parallel with the pipe for making the compressed air flow and the plurality of pipes 14-16 connected in parallel are formed having different lengths so as to possess interference type silencer function. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an air compressor, and is particularly suitable for an air compressor including a positive displacement compressor body and a heat exchanger for cooling the compressed air.

  A positive displacement air compressor represented by a screw type or a scroll type has a structure in which a compression chamber is formed inside and the volume of the compression chamber is reduced by power from the outside. The air sucked from the atmosphere is confined in the compression chamber and the volume is reduced to compress the air. When the pressure reaches a predetermined pressure, the compression chamber is opened downstream to discharge the compressed air. This series of operations is repeated to supply compressed air to the outside. Since the displacement compressor discharges intermittently in this way, when the discharge pulsation of the compressed air that is discharged occurs and propagates downstream, the piping system is vibrated and noise becomes a problem. There is. Therefore, a silencer is provided downstream of the compressor body for the purpose of reducing pulsation.

  Further, since the air discharged from the air compressor main body becomes high temperature due to the compression heat, it is necessary to send out after cooling for the purpose of safety, maintenance management, or prevention of drain generation due to condensation of water vapor downstream. Therefore, a heat exchanger is usually provided downstream of the compressor body. There are mainly air-cooled and liquid-cooled heat exchangers. In many cases, the cooling liquid of the liquid-cooled heat exchanger is ordinary water or water to which anti-freezing or anti-corrosion chemicals are added.

  As a compressor related to the related art, there is JP-A-6-173878 (Patent Document 1).

JP-A-6-173878

  However, in the conventional air compressor, a silencer and a heat exchanger are provided independently and separately on the downstream side of the compressor body, so that a large space is required around the compressor body, and it is complicated and expensive. It was a simple structure.

  An object of the present invention is to realize a low noise air compressor with a compact, simple and inexpensive structure.

To achieve the foregoing object, the present invention comprises a positive displacement compressor body for compressing air,
A heat exchanger having a pipe for flowing compressed air discharged from a discharge port of the compressor body, wherein the heat exchanger has a plurality of pipes for flowing the compressed air connected in parallel. A plurality of pipes connected in parallel are formed with different lengths so as to have an interference-type silencer function. (Claim 1)
A more preferable specific configuration example of the present invention is as follows.
(1) The difference between the pipes having different lengths in the heat exchanger is set to a length that is about half of the wavelength that propagates as the discharge pulsation of the compressed air discharged from the compressor body. (Claim 2)
(2) In the above (1), a constant speed compressor main body having a substantially constant rotation frequency is used as the compressor main body, and the difference between the pipes having different lengths in the heat exchanger is determined by the constant speed compressor. The length is about half of the wavelength that propagates as the discharge pulsation of the compressed air that is discharged when the main unit is operated under rated operating conditions. (Claim 3)
(3) A plurality of pipes having different lengths are formed by connecting a plurality of pipes in the heat exchanger in parallel between opposing inlet headers and outlet headers, and forming folded portions in the middle of the pipes in the heat exchanger. Configured. (Claim 4)
(4) In the above (3), the heat exchanger is formed so that the folded portions of adjacent pipes in the heat exchanger overlap on a projection plane intersecting the pipe longitudinal direction. (Claim 5)
(5) A shell and tube type heat exchanger is used as the heat exchanger, and a plurality of tubes provided in the shell and tube type heat exchanger constitute the plurality of pipes connected in parallel. Flowing compressed air inside, filling the coolant inside the shell that covers the outside of the multiple pipes connected in parallel, and circulating it. (Claim 6)

  According to the air compressor of the present invention, low noise can be realized with a compact, simple and inexpensive structure.

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. The same reference numerals in the drawings of the respective embodiments indicate the same or equivalent.
(First embodiment)
An air compressor according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of a main part of an air compressor according to a first embodiment of the present invention.

  The air compressor 100 includes a positive displacement compressor main body 1 that compresses air and a heat exchanger 10 that includes pipes 14 to 16 through which compressed air discharged from the discharge ports 2 of the compressor main body 1 flows. Has been. The compressor body 1 is composed of a constant-speed screw-type air compressor body whose rotation frequency is substantially constant.

  The compressor main body 1 includes two male and female rotors that mesh with each other inside the casing, and rotates while the two rotors mesh with each other, and has a function of compressing and discharging the air confined in the tooth gap.

  The heat exchanger 10 is constituted by a shell and tube water-cooled heat exchanger, and a plurality of pipes 14 to 16 that are tubes constituting parallel flow paths are arranged in a cylindrical shell 11. The upstream side of the pipes 14 to 16 is communicated with the inlet header 4 that is a branch of the flow path, and the downstream side of the pipes 14 to 16 is communicated with the outlet header 5 that is a confluence of the flow paths. Note that, here, three pipes 14 to 16 are representatively shown, but it is normal to provide a larger number of pipes in practice.

  The shell 11 is provided with a partition plate 11a that partitions left and right and a partition plate 11b that partitions the top and bottom. The headers 4 and 5 and the liquid chamber 17 are partitioned by the partition plate 11a, and the inlet header 4 and the outlet header 5 are partitioned by the partition plate 11b. It arrange | positions so that the inside of the liquid chamber 17 of the piping 14-16 may be extended in U shape, The both ends are attached to the partition plate 11a, and are connected with the inlet header 4 and the outlet header 5, respectively. The liquid chamber 17 of the shell 11 covering the outside of the pipes 14 to 16 is filled with cooling water, and a water inlet 12 and a water outlet 13 for circulating the cooling water are provided in the shell 11.

  The discharge port 2 of the compressor body 1 and the inlet header 4 of the heat exchanger 10 are connected via a discharge pipe 3. In addition, a downstream pipe 6 that extends from the outlet header 5 to the outside is provided.

  The heat exchanger 10 includes a plurality of pipes 14 to 16 connected in parallel, and a plurality of pipes 14 to 16 connected in parallel so as to have an interference silencer function. They are formed with different lengths.

  In this embodiment, the difference between the pipes 14 and 15 having different lengths in the heat exchanger 10 is set to a length that is approximately half the wavelength that propagates as the discharge pulsation of the compressed air that is discharged from the compressor body 1. The difference between the pipes 14 and 16 having different lengths in the exchanger 10 is set to about three times (odd times) the half length of the wavelength propagating as the discharge pulsation of the compressed air discharged from the compressor body 1. For example, it is assumed that the basic frequency of the discharge pulsation when the constant speed compressor main body 1 is operated under the rated operation condition is 500 Hz by multiplying the rated rotation frequency of the rotor 100 Hz (6000 rotations per minute) by the number of teeth 5. If the sum of the sound velocity and the pipe flow velocity is 400 m / s, the wavelength is 0.8 m. Accordingly, since one half of the wavelength of the discharge pulsation is 0.4 m, the difference between the pipes 14 and 15 having different lengths among the plurality of pipes is set to 0.4 m. The noise can also be effectively reduced by setting the difference between the pipes 14 and 16 having different lengths to about three times (odd times) the half length of the wavelength propagating as the discharge pulsation of compressed air.

  The effect of the air compressor 100 having the above-described configuration will be described more specifically together with the operation.

  A pressure pulsation is generated as a pressure wave from the outlet 2 of the compressor body 1, propagates in the flow of the compressed air, propagates through the discharge pipe 3, and reaches the inlet header 4. The flow of compressed air branches at the inlet header 4, passes through the pipes 14 to 16, and rejoins at the outlet header 5. Here, since the flow lengths of the pipes 14 to 16 are different, the propagation time of the pulsation is also different, and the phase of the pulsation that is a dense wave is shifted. The amplitude decreases due to the merging of the pulsations that are out of phase, canceling each other when the phase is the most ideal difference of 180 degrees, and completely canceling if the pulsation intensity is the same.

  In addition, if it is made to have many types of pipes with different lengths, even if the operating conditions and operating speed change, even if the pulsation frequency and sound speed change, the pulsations cancel each other out, so A certain amount of pulsation reduction effect can be maintained.

  When a pulsating wave of compressed air passes through the inside of the pipes 14 to 16, pressure fluctuation is exerted on the pipe wall, and when the pipe wall is thin, there is a concern that noise is diffused to the outside. However, according to the present embodiment, the cooling water is filled around the pipes 14 to 16, and a large radiation noise suppressing effect can be expected as compared with the conventional silencer provided in the air. Since the density of water is much larger than that of air, the vibration of the tube wall is suppressed and the vibration amplitude is also reduced.

According to the structure of the present embodiment, the connection work between the pipes 14 to 16 and the headers 4 and 5 may be performed on one side of the shell 10, and the assembly work is relatively easy. Further, since the pressure loss of the pipes 14 to 16 greatly depends on the number of bendings and the number of entrances and exits rather than the length, the difference in pressure loss for each pipe is small, and a relatively uniform flow can be obtained. Therefore, the heat transfer performance as the heat exchanger 10 can also be maintained high.
(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a cross-sectional view of a main part of an air compressor according to a second embodiment of the present invention. The second embodiment is different from the first embodiment in the points described below, and the other points are basically the same as those in the first embodiment, and thus redundant description is omitted.

  In the second embodiment, the heat exchanger 10 is provided such that the inlet header 22 and the outlet header 23 face both ends of the shell 21, and a plurality of pipes 24 to 26 are connected to the inlet header 22, the outlet header 23, and the like. Are connected in parallel.

  The heat exchanger 10 includes a plurality of pipes 24 to 26 connected in parallel to form a flow path for flowing compressed air, and has an interference silencer function for the plurality of pipes 24 to 26 connected in parallel. Are formed with different lengths. Specifically, the plurality of pipes 24 to 26 are a pipe 24 that connects the inlet header 22 and the outlet header 23 with a straight line as short as possible, and a length that is folded halfway and connects the inlet header 22 and the outlet header 23. The pipes 25 and 26 are different in length. And in this 2nd Embodiment, the difference of the pipes 24 and 25 of different length in the heat exchanger 10 is made into the length of about half of the wavelength which propagates as discharge pulsation of the compressed air discharged from the compressor main body 1. In addition, the difference between the pipes 24 and 26 having different lengths in the heat exchanger 10 is approximately three times (odd times) the half length of the wavelength that propagates as the discharge pulsation of the compressed air discharged from the compressor body 1. It is said. With this configuration, the interference silencer function by the heat exchanger 21 can be achieved in the second embodiment as well as in the first embodiment.

  Furthermore, in 3rd Embodiment, the heat exchanger 21 is formed so that the folding | returning part of the adjacent piping 25 and 26 may overlap on the projection surface which cross | intersects a piping longitudinal direction. Thereby, the pipes 25 and 26 having different lengths can be obtained in a compact manner.

  In FIG. 2, three types of pipes 24 to 26 are schematically shown as representatives. However, the pipes are longer than the pipes 26 by providing more pipes of various lengths and increasing the number of turns. You can also

According to 2nd Embodiment, the freedom degree of the layout inside an air compressor can be increased by separating | separating the entrance and exit of the heat exchanger 21. FIG. Further, since the pipes 24 to 26 can be arranged in the shell 21 with a relatively high density, the heat exchanger 21 can be realized in a compact manner. Furthermore, the selection of the opening positions of the pipes 24 to 26 on the inner surfaces of the headers 22 and 23 has a relatively large degree of freedom, so that the design according to the pulsation frequency to be reduced is easy.
(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a sectional view of an essential part of an air compressor according to a third embodiment of the present invention. The third embodiment is different from the second embodiment in the following points, and the other points are basically the same as those in the second embodiment, and thus redundant description is omitted.

  In the third embodiment, the heat exchanger 50 includes an inlet header 52 and an outlet header 53 inside a shell 51, and the inlet header 52 and the outlet header 53 are supported by an inlet pipe 54 and an outlet pipe 55. The inlet header 52 and the outlet header 53 are connected by a plurality of short pipes 56 and long pipes 57. The outlet 2 of the compressor body 1 and the inlet pipe 54 of the heat exchanger 50 are connected by a flexible pipe 58, and the cover 59 covers the periphery of the flexible pipe 58. The cover 59 is fixed to the shell 51 and is slightly separated from the compressor body 1.

  In FIG. 3, two types of pipes 56 and 57 are schematically shown as a representative. However, the pipes 57 may be longer than the pipe 57 by providing more pipes having various lengths.

According to the third embodiment, since the compressor body 1 and the heat exchanger 50 are connected by a flexible structure, solid propagation vibration generated in the compressor body 1 is difficult to be transmitted to the heat exchanger 50, The shell 51 can be prevented from generating noise due to the vibration. Further, since the headers 52 and 53 are inside the shell 51, it is possible to prevent noise that discharge pulsation vibrates the wall surface of the header and diffuses to the outside.
(Other embodiments)
In the first to third embodiments described above, the screw type compressor has been described as an example. However, discharge pulsation similarly occurs even in a positive displacement air compressor based on other principles such as a scroll type or a reciprocating type. Therefore, by providing these air compressors with the same heat exchangers as those of the above-described embodiments, it is possible to expect a discharge pulsation reduction effect and a radiation noise reduction effect from the heat exchanger with a compact structure. Moreover, the structure of the heat exchanger of each embodiment mentioned above can be applied not only to the latter stage of the single stage compressor but also to the intermediate cooler of the two stage compressor.

It is principal part sectional drawing of the air compressor of 1st Embodiment of this invention. It is principal part sectional drawing of the air compressor of 2nd Embodiment of this invention. It is principal part sectional drawing of the air compressor of 3rd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Compressor body, 2 ... Discharge port, 3 ... Discharge piping, 4 ... Inlet header, 5 ... Outlet header, 6 ... Downstream piping, 10 ... Heat exchanger, 11 ... Shell, 12 ... Water inlet, 13 ... Water outlet , 14-16 ... piping, 21 ... shell, 22 ... inlet header, 23 ... outlet header, 24-26 ... piping, 50 ... heat exchanger, 51 ... shell, 52 ... inlet header, 53 ... outlet header, 54 ... inlet Pipe 55, outlet pipe, 56 short pipe, 57 long pipe, 58 flexible pipe, 59 pipe cover.

Claims (6)

A positive displacement compressor body for compressing air;
In an air compressor comprising a heat exchanger having a pipe through which compressed air discharged from a discharge port of the compressor body flows.
The heat exchanger is configured with a plurality of pipes connected in parallel to the pipe through which the compressed air flows, and the plurality of pipes connected in parallel are formed with different lengths so as to have an interference-type silencer function. thing,
Features an air compressor.   In the air compressor according to claim 1, the difference between the pipes of different lengths in the heat exchanger is set to a length of about half of the wavelength propagating as a discharge pulsation of the compressed air discharged from the compressor body. Features an air compressor.   3. The air compressor according to claim 2, wherein a constant speed type compressor body having a substantially constant rotation frequency is used as the compressor body, and the difference between the pipes having different lengths in the heat exchanger is determined by the constant speed type. An air compressor characterized by having a length that is approximately half of the wavelength that propagates as discharge pulsation of compressed air that is discharged when the compressor body is operated under rated operating conditions.   The air compressor according to any one of claims 1 to 3, wherein a plurality of pipes in the heat exchanger are connected in parallel between opposing inlet headers and outlet headers, and in the middle of the pipes in the heat exchanger. An air compressor characterized in that the pipes having different lengths are formed by forming folded portions.   5. The air compressor according to claim 4, wherein the heat exchanger is formed such that a folded portion of an adjacent pipe in the heat exchanger overlaps with a projection plane intersecting a pipe longitudinal direction. Machine. The air compressor according to any one of claims 1 to 5, wherein a shell and tube heat exchanger is used as the heat exchanger, and a plurality of tubes provided in the shell and tube heat exchanger include the shell and tube heat exchanger. Compressed air is flowed inside so as to constitute a plurality of pipes connected in parallel, and a coolant is filled inside the shell covering the outside of the plurality of pipes connected in parallel to circulate. air compressor.

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