JP2008274840A - Air compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attenuate noise as much as possible in a crank case 4 leaking to the outside through an intake air passage. <P>SOLUTION: In an air compressor having a crankshaft 3 provided in a crank case 4 connected to a compression piston 18 in a compression cylinder 20 via a connecting rod 16, introducing air into the crank case 4 from an intake hole 24 formed on a wall of the crank case 4 and taking the same into the compression cylinder 20, compressing the air by the compression piston 21 and delivering the same, an air passage connecting to the intake hole 24 is formed at an outside of the crank case 4, and restriction parts and expansion parts are alternately and repeatedly formed in the intake air passage. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an air compressor provided with a structure that reduces noise generation.

  Air compressors are used in a variety of applications. For example, reflecting the recent expansion of the home renovation market, it is possible to respond to the use of various pneumatic tools such as nailers at home construction sites. An air compressor is brought in. However, since the renovation work is normally performed in the home state of the resident, noise generated from the compressor becomes a problem when the compressor is used at the renovation site.

For this reason, various noise countermeasures have been conventionally taken in air compressors. For example, in a case where a cooling fan is provided at the end of the crankshaft of a reciprocating air compressor, It is known that the noise in the crankcase is prevented from leaking directly from the vent of the cooling fan housing chamber by partitioning the fan housing chamber with a partition plate (for example, see Patent Document 1). In this case, an intake hole provided with a separate filter is provided in the wall of the case for taking air into the crankcase.
JP-A-8-28470

  By the way, there are various sources of noise in the air compressor, and it varies depending on the type of the compressor. In the reciprocating type air compressor, the sound of the intake valve, particularly the bearing in the crankcase, There is a tendency that the noise generated when the bearing part slides increases, and the main countermeasure for noise is how to suppress the noise leaking from the inside of the crankcase to the outside.

  And the noise countermeasure in the air compressor of the above-mentioned patent document 1 from the said viewpoint, the noise in a crankcase is accommodated in a cooling fan by partitioning between the inside of a crankcase and a cooling fan accommodation chamber by a partition plate. It is designed not to leak to the vent side of the room. However, in this known noise countermeasure, an intake hole for taking in air into the crankcase is separately provided in order to block the intake port for taking in air into the crankcase by the partition plate.

  The intake hole is composed of a plurality of relatively small holes, and the plurality of intake holes are directly open to the wall of the crankcase and are through the filter, but directly open to the outside, and the intake holes Is substantially the length of the thickness of the case wall, and the noise in the crankcase leaks directly to the outside through the intake hole. However, no special noise countermeasures have been taken in these air intake holes, and it cannot be said that the compressor has sufficient noise countermeasures, such as in the home renovation site where the residents are at home. The use of an air compressor is not preferable because of the influence of noise on residents.

  Under the circumstances as described above, the present invention can make noise in the crankcase leaking outside through the intake passage by applying a special structural device to the intake passage for introducing the atmosphere into the crankcase. It is an object of the present invention to provide an air compressor that is damped as much as possible.

  In order to solve the above problems, an invention according to claim 1 is characterized in that a crankshaft provided in a crankcase is connected to a compression piston in a compression cylinder and a crank is formed from an intake hole formed in a wall of the crankcase. In an air compressor that introduces air into the case and further compresses and discharges the air taken into the compression cylinder by the compression piston, an air passage continuing to the intake hole is formed outside the crankcase, In the intake passage, a throttle portion and an expansion portion are alternately and repeatedly formed.

  The invention according to claim 2 is the invention according to claim 1, characterized in that a filter is provided in the intake passage.

  The invention according to claim 3 is characterized in that, in the invention according to claim 1, the direction of the final opening of the intake passage is provided in a direction not facing the adjacent cover.

  The invention according to claim 4 is the invention according to claims 1 to 3, wherein the wall is a case cap of the crankcase.

  According to the first aspect of the present invention, the air compressor is introduced into the crankcase through the intake holes formed in the wall of the crankcase, and the air taken into the compression cylinder is compressed by the compression piston and discharged. In this case, an air passage continuing to the intake hole is formed outside the crankcase, and the throttle portion and the expansion portion are alternately and repeatedly formed in the intake passage, so that the noise in the crankcase leaking outside through the intake passage. Since the energy is diffused in the expansion part in the intake passage and is squeezed in the throttle part, the energy due to air vibration is lost by passing through the intake passage, and the friction between the wall of the intake passage and the air Since it is attenuated by the friction loss caused by the noise, the noise is greatly reduced.

  According to the invention according to claim 2, in the invention according to claim 1, since the intake passage is provided with a filter, the intake air can be purified and noise leaked from the inside of the crankcase to the outside. Can be reduced.

  According to the invention according to claim 3, in the invention according to claim 1, since the direction of the final opening of the intake passage is provided in a direction not facing the adjacent cover, intake noise from the collection opening is from the cover. I can't hear it directly.

  According to the fourth aspect of the present invention, since the wall formed with the intake hole is the case cap of the crankcase, it is easy to remove, and the intake hole can be easily clogged or the filter can be replaced. .

  The structure of the air compressor of the present invention will be described with reference to FIGS.

  The air compressor A according to the present invention is of a reciprocating type, and includes a motor case 2 that houses the electric motor 1, a crankcase 4 having a crankshaft 3, and two compressors 5 and 6.

  A stator 7 of the electric motor 1 is disposed in the motor case 2. The stator 7 is composed of a stator coil or the like, and surrounds the rotor 8 from the outer peripheral side. The rotor 8 is made of a permanent magnet or the like and is provided integrally with the rotary shaft 10. The rotor 8 rotates the rotating shaft 10 by electromagnetic force acting between the stator 7, and the rotating shaft 10 extends in the crankcase 4. The crankcase 4 is rotatably supported by a motor-side end wall 11 and a ball bearing 13 provided at the center of the case cap 12.

  Moreover, one end of the rotating shaft 10 protrudes to the outside of the motor case 2 and a cooling fan 14 is fixed. A cooling air intake guide plate 15 is formed between the electric motor 1 and the cooling fan 14, and the electric motor 1 is cooled by the cooling air sent by the rotation of the cooling fan 14.

  In the crankcase 4, the crankshaft 3 is configured integrally with the rotary shaft 10 of the electric motor 1. Two connecting rods 16, 17 are connected to the crankshaft 3 through a bearing 9, one connecting rod 16 is connected to a compression piston 18 of the primary compressor 5, and the other connecting rod 17 is compressed by the secondary compressor 6. It is connected to the piston 21.

  The compression piston 18 of the primary compressor 5 is slidably accommodated in a cylindrical compression cylinder 20. A compression piston (not shown) of the secondary compressor 6 is slidably accommodated in a cylindrical compression cylinder 21. The atmosphere is introduced into the compression cylinder 18 of the primary compressor 5. That is, the air is introduced into the crankcase 4 from an intake hole 24 (described later) formed in the case cap 12 of the crankcase 4, and is further introduced into the compression piston 18 of the primary compressor 5 with an introduction hole with a check valve ( It is configured to be taken into the compression cylinder 20 from (not shown). The compression cylinder 21 of the secondary compressor 6 is configured to be supplied with primary pressure air discharged from the primary compressor 5, and the compressed air compressed by the secondary compressor 6 is supplied to an external air tank (not shown). It is supplied and stored.

  That is, when the electric motor 1 is operated, the crankshaft 3 is rotated together with the rotary shaft 10, so that the rotation is converted into a reciprocating motion by the connecting rod 16 of the primary compressor 5, and the compression piston 18 reciprocates in the compression cylinder 20. When the compression piston 18 moves backward in the intake process, the space in the compression cylinder 20 suddenly expands, so that the inside becomes negative pressure, the introduction hole is opened, and the air in the crankcase 4 is introduced into the compression cylinder 20. . When the compression piston 18 moves forward in the compression process, the space in the crankcase 4 suddenly expands, so that air is taken into the crankcase 4 and the space in the compression cylinder 20 shrinks at the same time. Therefore, the introduction hole is closed, and a discharge port (not shown) formed in the compression cylinder 20 is opened to discharge compressed air. Thereby, the air sent into the compression cylinder 20 is compressed in the compression cylinder 20 and discharged as primary pressure air. The primary pressure air is supplied from the air outlet pipe 22 of FIG. 1 to the compression cylinder 21 of the secondary compressor 6 through the air introduction pipe 23 of the secondary compressor 6. The primary pressure air in the compression cylinder 21 is further compressed by a compression piston that reciprocates in the same manner, discharged as secondary pressure air, boosted, supplied to an air tank, and stored.

  As described above, the air is sent into the crankcase 4 from the intake hole 24, but an intake passage is formed in front of the intake hole 24 and is introduced into the intake hole 24 after passing through the intake passage. Has been. Therefore, the intake passage will be described in detail next.

  The case cap 12 is formed in a dish shape whose center is recessed toward the inside of the crankcase 4 by casting or the like, and as shown in FIG. 2, the outer peripheral edge thereof is at the opening edge 25 at the end of the crankcase 4. It is fixed with bolts 26. At the center and one end of the case cap 12, a standing wall 30 is formed by continuously forming a circular wall 27 and a square wall 28, and a scoop-like lid plate 31 is disposed on the standing wall 30. It is fixed to a mounting boss provided on the cap 12 with a bolt 19 or the like (see FIG. 3). A reinforcing rib 32 is formed outside the standing wall 30.

  An intake passage (shown by a solid arrow in FIG. 4) is formed on the case cap 12 between the standing wall 30 and the cover plate 31. That is, the intake passage is constituted by the following space. A relatively wide central space S1 is formed at the center of the circular wall 27, and a plurality of partition walls 33 are formed radially around the central space S1. Therefore, between the adjacent partition walls 33, a booth space S2 that is continuous with the central space S1 is formed. Further, a part of the wall 35 of the connecting wall 34 between the circular wall 27 and the square wall 28 is cut out and formed so as to communicate from one booth space S2 to the square space S3 of the square wall 28. An intake opening 36 is formed as a final opening on the front end side of the rectangular space S3 in a direction not facing the adjacent cover 29, and in the booth space S2 on the primary compressor 5 side. The case cap 12 is formed with a through hole 24 communicating with the inside of the crankcase 4. At least one intake hole 24 is formed in each booth space S2 (two to three are preferable). A filter 37 (see FIG. 3) is disposed in the booth space S2 having the intake holes 24.

  Since the intake passage is configured as described above, the air that has entered from the intake opening 36 passes through the intake passage and passes through the rectangular space portion S3 and the booth space portion S2, as shown in FIG. It is introduced into the crankcase 4 through the intake hole 24 of the booth space S2 on the opposite side from the portion S1.

  Next, noise (air density waves) generated inside the crankcase 4 mainly leaks from the intake holes 24, which are a plurality of small holes, but is filtered from the narrow intake holes 24 as shown by dotted arrows in FIG. After passing through 37 and exiting into the wide booth space S2 in the foreground, and further diffusing from this booth space S2 into the wider central space S1, it also spreads to the surrounding booth space S2, and finally Is advanced to the rectangular space S3 through the notch 35 of the connecting wall 34 and leaked from the intake opening 36 to the outside. As described above, the noise (sound wave) in the crankcase 4 travels through a relatively long leakage path before leaking from the intake passage to the outside, and the intake hole 24 serves as a throttle portion, and the booth space is formed in the intake hole 24. In contrast, the central space portion S1 is a further expanded portion, and the screwing boss portion 38 is a constricted portion with respect to the central section portion S1 in the central section portion S1, and the booth space is a central space portion. Compared with S1, it becomes a throttle part, the notch part 35 becomes a throttle part, and square space part S3 becomes an expansion part. As described above, the throttle portion and the expansion portion are relative to each other, but proceed while being diffused by the expansion portion or being throttled by the throttle portion in the course of the leakage path. In addition, the leakage path mainly composed of the intake passage is not linear but is winding. Therefore, the energy due to the air vibration of the noise is lost by passing through the intake passage, and is attenuated by the friction loss caused by the friction between the wall of the intake passage and the air, so that the noise is greatly reduced.

  In this way, the noise in the crankcase 4 leaking through the intake passage changes direction between the fine bumps formed by the plurality of expansion portions and the throttle portions in the intake passage formed in the case cap 12 of the case. However, when slipping through a long path, it is attenuated by the energy loss effect due to energy loss due to air vibration, damping effect due to friction and reflection of the passage wall surface and air, and increased friction loss, etc. The noise of the compressor A is greatly reduced.

  Note that noise can be further reduced by providing the filter 37 on the wall surface of an appropriate location such as the vicinity of the intake hole 24 of the intake passage.

  The intake passage in the crankcase 4 is formed in the case cap 12 and is formed by attaching the case cap 12 to the opening of the crankcase 4, so that the formation of the intake passage is easy, Costs for forming the intake passage can be reduced.

  Further, when the filter 37 in the intake hole 24 in the intake passage becomes dirty and the intake efficiency deteriorates, the filter 37 can be easily replaced by removing the case cap 12.

  Note that the intake hole 24 only needs to be able to take air into the crankcase 4, and the form formed in the case cap 12 is not particularly limited.

External perspective view of the air compressor of the present invention Vertical sectional view of the air compressor Front view showing a part of the air compressor in cross section Front view showing main part of case cap

Explanation of symbols

A Air compressor 3 Crankshaft 4 Crankcase 12 Case cap 18 Compression piston 20 Compression cylinder 24 Intake hole 37 Filter

Claims (4)

Air that is connected to the compression piston in the compression cylinder via a crankshaft provided in the crankcase, introduced into the crankcase from the intake hole formed in the wall of the crankcase, and further introduced into the compression cylinder In an air compressor that compresses and discharges the air by the compression piston,
An air compressor characterized in that an air passage continuing to the intake hole is formed outside the crankcase, and a throttle portion and an expansion portion are alternately and repeatedly formed in the intake passage.   The air compressor according to claim 1, wherein a filter is provided in the intake passage.   2. The air compressor according to claim 1, wherein the direction of the final opening of the intake passage is provided in a direction that does not face an adjacent cover. 3.   The air compressor according to any one of claims 1 to 3, wherein the wall is a case cap of the crankcase.

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