Air compressor

Abstract

To provide an air compressor including a filter cleaning mechanism capable of efficiently removing dust accumulated on a filter.SOLUTION: An air compressor 1 has an inner filter 32 covering an intake port 31b. The air compressor 1 has an outer filter 34 which covers the inner filter 32 from the outside and which is easily air-permeable than the inner filter 32. The air compressor 1 has a cleaning pipe 16 extending from a tank storing compressed air. The air compressor 1 has a cleaning intake port 16a connected to the cleaning pipe 16 for introducing compressed air between the inner filter 32 and the outer filter 34.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to an air compressor that supplies compressed air to air tools such as compressed air-driven nailers and air dusters. [Background technology]

[0002] Conventionally available air compressors have, for example, a reciprocating compression mechanism that generates compressed air. The compression mechanism converts the rotational output of a motor into the reciprocating motion of a piston in a cylinder using a crank mechanism. Compressed air is generated by compressing outside air with the piston. The compressed air generated by the compression mechanism is stored in a tank. The compressed air stored in the tank is supplied to pneumatic tools such as compressed air-driven nailers and air dusters.

[0003] When generating compressed air, outside air is introduced into the crankcase that houses the crank mechanism. The intake section that introduces outside air into the crankcase is provided with an intake port that connects the inside and outside of the crankcase and a filter that covers the intake port. The filter prevents dust and other particles contained in the introduced outside air from entering the crankcase through the intake port. The filter also suppresses the operating noise of the crank mechanism from leaking outside the crankcase. For this reason, for example, wool felt or the like having a predetermined thickness is used for the filter.

[0004] When an air compressor is used repeatedly, dust accumulates on the outer surface of the filter. When the accumulated dust clogs the filter, its breathability is impaired. If the air compressor is used with the filter's breathability impaired, for example, outside air and dust may enter the crankcase through the gap between the outer edge of the filter and the crankcase. Filter cleaning mechanisms to prevent filter clogging have been proposed. The filter cleaning mechanism described in Patent Document 1 blows compressed air stored in a tank onto the filter in conjunction with the operation of shutting down the air compressor. The operation of shutting down the air compressor is, for example, by turning off the main power switch. Therefore, the filter cleaning mechanism cannot be activated unless the compressor is connected to a power source, making it impossible to clean the filter, for example, away from the work site. The filter cleaning mechanism can also be activated if the main power switch is accidentally turned on.

[0005] The filter cleaning mechanism described in Patent Document 2 reverse-jet compressed air stored in a tank into the crankcase. This causes a reverse jet of air to flow from the inner surface of the filter to the outer surface through the crankcase's air intake, blowing away dust that has accumulated on the outer surface. However, the filter is made of thick wool felt to prevent sound leakage. Therefore, in order to blow away dust that has accumulated on the outer surface of the filter from the inner surface, it is necessary to increase the air pressure and flow rate of the reverse jet.

[0006] Patent Document 3 describes a structure in which a filter is made up of multiple layers, and only the clogged filter layer is replaced to maintain breathability. By using multiple layers of filters, it is possible to further prevent dust from entering the crankcase and noise from escaping from within the crankcase. However, it is difficult for users to maintain the airtightness of the crankcase before and after replacing the filters. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 7005765 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-127506 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-023851 Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, there is a need for an air compressor equipped with a filter cleaning mechanism that can efficiently remove dust accumulated on the filter. [Means for solving the problem]

[0009] According to one aspect of the present disclosure, an air compressor has an inner filter that covers an air intake port. The air compressor has an outer filter that covers the inner filter from the outside and allows air to pass through more easily than the inner filter. The air compressor has a cleaning pipe extending from a tank that stores compressed air. The air compressor has a cleaning air intake port that is connected to the cleaning pipe and introduces compressed air between the inner filter and the outer filter.

[0010] Therefore, by providing an inner filter and an outer filter, dust can be prevented from entering the crankcase and noise leakage from within the crankcase can be suppressed. Furthermore, compressed air is introduced from the tank via the cleaning pipe and cleaning air intake into the area between the inner and outer filters. This allows compressed air to flow from the inner side of the outer filter to the outer side, blowing accumulated dust outward. Even if the air compressor is not connected to a power source, compressed air can be introduced from the tank to the cleaning air intake mechanically or manually by connecting a valve or cock to the cleaning pipe, for example. This allows efficient removal of dust accumulated on the outer or inside surface of the outer filter or the outer surface of the inner filter. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view of an air compressor according to an embodiment of the present disclosure, viewed from the right front. [Figure 2] This is an oblique view of the air compressor with the main body cover removed, viewed from the left rear. [Figure 3] This is a left side view of the air compressor with the main body cover and cooling fan removed. [Figure 4] FIG. 4 is a cross-sectional view of the air compressor taken along line IV-IV in FIG. 3. [Figure 5] 5 is a cross-sectional view taken along the line VV in FIG. 4. [Figure 6] FIG. 2 is an exploded perspective view of the intake section as seen from the left rear. [Figure 7] FIG. 2 is an exploded perspective view of the intake section as seen from the front right. [Figure 8] 8 is a cross-sectional view of the intake section taken along line VIII-VIII in FIG. 3. [Figure 9] 9 is a cross-sectional view taken along line IX-IX in FIG. 8. [Figure 10] 9 is a cross-sectional view taken along the line XX in FIG. 8. DETAILED DESCRIPTION OF THE INVENTION

[0012] According to another feature of the present disclosure, the outer filter is thinner than the inner filter. Therefore, even if the air pressure of the compressed air introduced into the cleaning intake port is significantly lower than that of the compressed air in the tank, dust can be blown from the inner side to the outer side of the outer filter and removed. The dustproofness and soundproofing of the crankcase can be maintained by making the inner filter thicker than the outer filter.

[0013] According to another feature of the present disclosure, the outer filter has a coarser mesh than the inner filter. Therefore, even if the compressed air introduced into the cleaning intake port has a significantly lower air pressure than the compressed air in the tank, dust can be blown from the inner side to the outer side of the outer filter and removed. The dustproofness and soundproofing of the crankcase can be maintained by making the inner filter finer than the outer filter.

[0014] According to another feature of the present disclosure, a sealed space into which compressed cleaning air is introduced is formed between the inner filter and the outer filter. Therefore, compressed air sent from the cleaning air intake temporarily accumulates in the sealed space between the inner filter and the outer filter. The compressed air that does not fit into the sealed space flows toward the outer surface of the outer filter. Therefore, by guiding the compressed air path toward the outer surface of the outer filter, dust can be removed more efficiently.

[0015] According to another feature of the present disclosure, a spacer is provided between the inner filter and the outer filter. This prevents the outer surface of the inner filter from coming into close contact with the inner surface of the outer filter. This maintains a space between the inner filter and the outer filter through which compressed air can flow. This allows dust to be removed by compressed air from the inner filter, the outer filter, or the area between both filters.

[0016] According to another feature of the present disclosure, the spacer has an outer peripheral wall that covers the outer peripheral edges of the inner filter and the outer filter, thereby airtightly sealing the outer peripheral edges of the inner filter and the outer filter, thereby improving the dustproofness and soundproofing of the crankcase.

[0017] According to another feature of the present disclosure, the air compressor has a cover that covers the outer filter from the outside. The cover has outer ribs that hold the outer surface of the outer filter. The spacer has inner ribs that hold the inner surface of the outer filter at positions corresponding to the outer ribs. Therefore, the outer ribs and inner ribs face each other to hold the outer filter in place. This prevents the outer filter from shifting due to compressed air. This prevents gaps around the outer filter that allow dust to enter.

[0018] According to another feature of the present disclosure, the air compressor has a cover that covers the outer filter from the outside. The cover has a connecting pipe that connects the cleaning pipe so that it opens between the inner filter and the outer filter. Therefore, compressed air can be introduced between the inner filter and the outer filter while preventing dust from accidentally entering between the inner filter and the outer filter.

[0019] According to another feature of the present disclosure, the cleaning air intake is open along the outer surface of the inner filter and the inner surface of the outer filter. This allows compressed air to flow along the outer surface of the inner filter and the inner surface of the outer filter. This more reliably blows away dust accumulated on the outer surface or inside of the outer filter or on the outer surface of the inner filter. It also prevents dust from entering the interior of the inner filter from the outer surface.

[0020] According to another feature of the present disclosure, the opening of the cleaning pipe is a cleaning air intake, so that compressed air with a relatively high air pressure coming out of the opening of the cleaning pipe can flow between the inner filter and the outer filter, thereby blowing away dust accumulated on the inner filter or the outer filter with great force.

[0021] Next, one embodiment of the present disclosure will be described with reference to FIGS. 1 to 10. As shown in FIGS. 1 and 2, an air compressor 1 has two cylindrical tanks 2 that are long from front to back. The two tanks store the generated compressed air. A total of four legs 2a are provided at the front and back of the two tanks 2. Each leg 2a is made of a rubber material with high vibration damping properties. Side protectors 2b are provided on the top of each leg 2a. The tops of the two tanks 2 are connected to each other by a base 3. A main body 10 that generates compressed air is mounted on the top surface of the base 3. The main body 10 is covered by a main body cover 4 that is attached above the two tanks 2. Carrying handles 3a are provided at the front and rear of the base 3, spanning the tops of the two tanks 2.

[0022] As shown in FIG. 1, the front of the main body cover 4 is provided with two low-pressure outlets 5 and two high-pressure outlets 6. Compressed air of, for example, 0.85 MPa is supplied from the low-pressure outlet 5. Compressed air of, for example, 2.5 MPa is supplied from the high-pressure outlet 6. Adjustment dials 5a and 6a for setting the discharge pressure are provided above the outlets 5 and 6, respectively. An operation panel 4b equipped with various display units and operation units mainly for startup operations, such as a power switch, is provided on the front upper surface of the main body cover 4. A plurality of air vents 4a are provided in a mesh pattern on the front, rear, left, and right sides of the main body cover 4. The air vents 4a on the rear and left surfaces of the main body cover 4 are not visible in FIG. 1.

[0023] As shown in Figure 1, a drain discharge device 7 is provided between the front parts of the two tanks 2 to discharge drain water accumulated in the tanks 2. The drain discharge device 7 has a drain cock 7a and a drain discharge pipe 7b. The drain cock 7a is closed when the air compressor 1 is in use. When the drain cock 7a is opened after using the air compressor 1, the drain water in the tanks 2 is discharged from the tip of the drain discharge pipe 7b.

[0024] As shown in Figures 2 to 4, the main body 10 has a cylindrical crankcase 20 in the center in the front-to-rear direction. The main body 10 has a first compression section 11 extending forward from the crankcase 20. The main body 10 has a second compression section 12 extending rearward from the crankcase 20. The crankcase 20 is fixed onto the base 3. A motor 21 is provided on the right side of the crankcase 20, between the first compression section 11 and the second compression section 12 in the front-to-rear direction.

[0025] As shown in Figures 2, 4, and 5, the motor 21 is a brushless motor capable of generating a relatively large starting torque. The motor 21 has an annular rotor 21a and a stator 21b, in which multiple coils are arranged in an annular shape on the inner periphery of the rotor 21a. The stator 21b is fixed to the right side of the crankcase 20. An output shaft 21c is coupled to the radial center of the rotor 21a. A cooling fan 22 is attached to the right end of the output shaft 21c. The cooling fan 22 rotates integrally with the output shaft 21c, thereby dissipating heat and cooling the motor 21. The output shaft 21c is rotatably supported by a right bearing 21d and a left bearing 21e, straddling the left and right sides of the crankcase 20. The left end of the output shaft 21c protrudes leftward via an intake section 30, which will be described later. A cooling fan 23 is attached to the left end of the output shaft 21c. Cooling fan 23 rotates integrally with output shaft 21c, so that outside air is blown into intake section 30, thereby cooling main body section 10.

[0026] As shown in FIGS. 2 to 4, a first cylinder 11a of the first compression section 11 is connected to the front of the crankcase 20 and extends in the front-rear direction. A second cylinder 12a of the second compression section 12 is connected to the rear of the crankcase 20 and extends in the front-rear direction. Outside air is taken into the crankcase 20 via an intake section 30. The first cylinder 11a takes in air from within the crankcase 20 via a communication passage not visible in the figure. A first piston 11b is housed within the first cylinder 11a and is capable of reciprocating back and forth. The first piston 11b is connected to a first crank 24 connected to an output shaft 21c via a first rod 11c extending in the front-rear direction. A second piston 12b is housed within the second cylinder 12a and is capable of reciprocating back and forth. The second piston 12b is connected to a second crank 25 connected to the output shaft 21c via a second rod 12c extending in the front-rear direction.

[0027] As shown in Figure 4, the first crank 24 and the second crank 25 are eccentric in the same direction around the output axis J. Therefore, when the first piston 11b moves forward in the first compression section 11 to perform the compression stroke, the second piston 12b moves forward in the second compression section 12 to perform the intake stroke. When the first piston 11b moves rearward in the first compression section 11 to perform the intake stroke, the second piston 12b moves rearward in the second compression section 12 to perform the compression stroke.

[0028] 2 and 4, a communicating pipe 13 is connected to the front of the first compression chamber 11d of the first cylinder 11a. The communicating pipe 13 communicates the first compression chamber 11d with the second compression chamber 12d of the second cylinder 12a. A check valve 11e is provided between the first compression chamber 11d and the communicating pipe 13 to prevent compressed air from flowing back from the communicating pipe 13 to the first compression chamber 11d. Compressed air that flows from the first compression chamber 11d through the check valve 11e and into the communicating pipe 13 is supplied to the second compression chamber 12d.

[0029] As shown in Figures 2 and 4, a supply pipe 14 is connected to the rear of the second compression chamber 12d of the second cylinder 12a. The supply pipe 14 branches into two branch pipes 14a, which are connected to the two tanks 2, respectively. A check valve 12e is provided between the second compression chamber 12d and the supply pipe 14 to prevent backflow of compressed air from the supply pipe 14 to the second compression chamber 12d. Compressed air flowing from the second compression chamber 12d through the check valve 12e into the supply pipe 14 is supplied to each tank 2. Thus, by starting the motor 21, compressed air is generated in two stages: the first compression section 11 and the second compression section 12. The compressed air compressed in the first compression section 11 is further compressed to a higher pressure, for example, 4.5 MPa, in the second compression section 12 and then sent to the tank 2.

[0030] As shown in Figures 2 to 4, a valve 15 is connected above the left tank 2. The valve 15 is connected to the interior of the left tank 2 and to a cleaning pipe 16 extending upward. The valve 15 has an inlet valve through which compressed air is sent from the tank 2 and an outlet valve through which compressed air is sent to the cleaning pipe 16. A space is provided between the inlet and outlet valves of the valve 15 in order to temporarily store a predetermined amount of compressed air. The inlet valve of the valve 15 opens when the pressure inside the tank 2 is, for example, 2 MPa or higher and closes when the pressure is lower than that. The inlet valve of the valve 15 closes when the pressure inside the tank 2 is, for example, 1.5 MPa or higher and opens when the pressure is lower than that.

[0031] Before using the air compressor 1, when the pressure inside the tank 2 is the same as atmospheric pressure, the outlet valve of the valve 15 is open but the inlet valve is closed. Therefore, compressed air is not discharged from the cleaning pipe 16. When the air compressor is started and the pressure inside the tank 2 increases, the outlet valve closes first. Therefore, compressed air is not discharged from the cleaning pipe 16. As the pressure inside the tank 2 increases further, the inlet valve opens. This allows some of the compressed air inside the tank 2 to accumulate in the space inside the valve 15. After using the air compressor 1, when the pressure inside the tank 2 drops, for example, when draining, the inlet valve of the valve 15 closes first. This stops the supply of compressed air from the tank 2 to the valve 15. As the pressure inside the tank 2 drops further, the outlet valve of the valve 15 opens. This allows the compressed air accumulated inside the valve 15 to flow into the cleaning pipe 16. In this way, compressed air can be mechanically and automatically discharged from the cleaning pipe 16 when the air compressor 1 is not in use.

[0032] As shown in Figures 2 to 5, an intake section 30 is provided on the left side of the crankcase 20. Outside air is introduced into the crankcase 20 through the intake section 30. The intake section 30 has a filter case (crankcase cover) 31 that covers a circular opening 20a provided at the left end of the crankcase 20. The intake section 30 has an inner filter 32 housed in the filter case 31. The intake section 30 has a cover 35 that is connected to the left side of the filter case 31 and covers the inner filter 32 from the left. The intake section 30 has an outer filter 34 that is housed in the cover 35 and is provided with a gap between it and the inner filter 32 in the left-right direction. The intake section 30 has a spacer 33 that is interposed to maintain the gap between the inner filter 32 and the outer filter 34. From right to left, the filter case 31, inner filter 32, spacer 33, outer filter 34, and cover 35 are assembled in an upright position.

[0033] 2, 6, and 7, the filter case 31 is disk-shaped. The filter case 31 is screwed to the left side of the crankcase 20 at its periphery. This allows the filter case 31 to close the opening 20a (see FIG. 4) of the crankcase 20. A filter housing section 31a capable of housing an inner filter 32 is recessed in the left side of the filter case 31. The filter case 31 is provided with a plurality of air intake ports 31b that open in a circular shape and penetrate in the left-right direction. The plurality of air intake ports 31b are provided on the bottom surface (right surface) of the filter housing section 31a. Outside air flows into the crankcase 20 through the air intake ports 31b.

[0034] As shown in FIGS. 5 to 7 , a cylindrical protrusion 31c that protrudes to the left is provided at the center of the filter case 31. A circular insertion hole 31d is provided at the center of the protrusion 31c, through which the output shaft 21c is inserted, penetrating the filter case 31 in the left-right direction. A bearing 21e is held in a recess on the right side corresponding to the protrusion 31c on the left side. A restricting plate 21f is screwed to the right side of the filter case 31 with four fixing screws 37 so as to cover the bearing 21e from the right. The restricting plate 21f restricts misalignment of the bearing 21e relative to the filter case 31 in the direction of the output axis J. A total of four protrusions 31e that protrude radially outward are provided at four equal circumferential positions of the protrusion 31c. Each protrusion 31e is provided with a screw hole 31f that extends in the left-right direction. Fixing screws 37 that screw-connect the restricting plate 21f to the filter case 31 are screwed into the screw holes 31f.

[0035] 5 and 6, a plurality of cylindrical bosses 31g protruding to the left are provided on the bottom surface of the filter case 31. In this embodiment, a total of four bosses 31g are provided at quarter-spaced positions around the circumference of the filter case 31. The bosses 31g and the protruding portions 31e are alternately provided at approximately 45° intervals around the circumference of the filter case 31. Each boss 31g is provided with a female thread 31h extending from the left end to the right. A fixing screw 36 is fastened to each female thread 31h, thereby threadably connecting the spacer 33 and the cover 35 to the filter case 31.

[0036] 5, 6, and 9, the inner peripheral surface of filter accommodating portion 31a is provided with approximately the same diameter as outer peripheral edge 32c of inner filter 32 so as to be in close contact with outer peripheral edge 32c. The depth of filter accommodating portion 31a is provided with approximately the same depth as the thickness of inner filter 32. Therefore, the left end face of filter case 31 and outer surface 32a of inner filter 32 are approximately flush with each other.

[0037] As shown in Figures 6 and 7, the inner filter 32 is made of, for example, felt and has a generally disk-like shape. The inner filter 32 has a left outer surface 32a and a right inner surface 32b. The outer surface 32a and the inner surface 32b are planar and generally parallel to each other. A circular insertion hole 32d is provided in the center of the inner filter 32, through which the protrusion 31c of the filter case 31 is inserted. Semicircular arc-shaped recesses 32f are provided at four equal circumferential positions of the insertion hole 32d, extending radially outward and through which the protrusions 31e of the filter case 31 are inserted. Four circular insertion holes 32e are provided around the insertion hole 32d, through which the bosses 31g of the filter case 31 are inserted.

[0038] As shown in Figures 6 and 7, the outer filter 34 is made of, for example, felt and has a generally disk-like shape. The material of the outer filter 34 may be the same as or different from that of the inner filter 32. The outer filter 34 has approximately the same shape and size as the inner filter 32 when viewed from the left and right. The outer filter 34 has a left outer surface 34a and a right inner surface 34b. The outer surface 34a and the inner surface 34b are planar and generally parallel to each other. An insertion hole 34d is provided in the center of the outer filter 34, through which a center rib 35e of the cover 35 (described later) is inserted from the left. At four equal circumferential positions of the insertion hole 34d, recesses 34f are provided that extend radially outward and through which protrusions 35f of the cover 35 (described later) are inserted from the left. Four insertion holes 34e are provided around the insertion hole 34d, through which bosses 31g of the filter case 31 are inserted.

[0039] 6 to 9 , the outer filter 34 is thinner in the left-right direction than the inner filter 32. The left-right thickness of the outer filter 34 is, for example, 50% or less, 40% or less, 30% or less, or 20% or less of the left-right thickness of the inner filter 32. Alternatively, the outer filter 34 has coarser meshes than the inner filter 32. The coarser meshes of the outer filter 34 are, for example, 50% or less, 40% or less, 30% or less, or 20% or less of the coarse meshes of the inner filter 32. When the outer filter 34 has coarser meshes than the inner filter 32, the outer filter 34 may be approximately the same thickness as or thicker than the inner filter, as long as the ease of air passage therethrough does not exceed that of the inner filter 32.

[0040] The material of the outer filter 34 may be the same as or different from the inner filter 32. If they are different materials, it is preferable that the inner filter 32 be made of a coarser or denser material. For example, the inner filter 32 may be made of animal fibers such as wool, chemical fibers such as rayon, or plant fibers such as kenaf, cotton, or hemp. For example, the outer filter 34 may be made of chemical fibers such as polyester or polypropylene.

[0041] As shown in Figures 5 to 9, a disk-shaped spacer 33 having approximately the same diameter as the inner filter 32 and the outer filter 34 is provided between the inner filter 32 and the outer filter 34 in the left-right direction. The spacer 33 is, for example, thicker in the left-right direction than the outer filter 34. A circular insertion hole 33b is provided in the center of the spacer 33, penetrating in the left-right direction and into which the output shaft 21c is inserted. Annular ribs extend to the right from the outer periphery of the insertion hole 33b. Recesses 33c, which extend radially outward in semicircular arcs from the insertion hole 33b, are provided at four equal positions in the circumferential direction of the insertion hole 33b. The protrusions 31c and protrusions 31e of the filter case 31 are inserted into the insertion hole 33b and the recesses 33c, respectively, from the right. The center-side rib 35e and protrusions 35f of the cover 35 are inserted into the insertion hole 33b and the recesses 33c, respectively, from the left.

[0042] 6 to 9, the spacer 33 has a plurality of beam portions 33f, 33g that extend linearly in the radial direction or arc-shaped in the circumferential direction. Beam portions 33g face retaining ribs 35h of the cover 35 (described later) in the left-right direction, while beam portions 33f face the retaining ribs 35h. A plurality of ventilation holes 33a that penetrate the spacer 33 in the left-right direction are formed between the beam portions 33f, 33g.

[0043] 6 and 7, four cylindrical tubular portions 33i are provided at equal quarter-spaced positions in the circumferential direction of the spacer 33. The tubular portions 33i and the recesses 33c are alternately provided at intervals of approximately 45° in the circumferential direction of the spacer 33. A circular insertion hole 33j is provided in the center of each tubular portion 33i, and the boss portion 31g of the filter case 31 is inserted therethrough.

[0044] 8 and 9, the spacer 33 is provided with a retaining rib 33h that protrudes to the right. The retaining rib 33h is provided on the right part of the outer peripheral wall 33d of the spacer 33, the right part of the insertion hole 33b, the right part of the beam part 33g, the right part of the cylindrical part 33i, etc. The retaining rib 33h abuts against the outer surface 32a of the inner filter 32 to hold down the inner filter 32. This restricts movement of the inner filter 32 relative to the spacer 33.

[0045] As shown in Figures 8 and 9, the spacer 33 forms a sealed space S between the inner filter 32 and the outer filter 34 in the left-right direction. The sealed space S is provided, for example, to the thickness of the spacer 33 in the left-right direction. The outer peripheral edge 32c of the inner filter 32 is airtightly held in the thickness direction by the filter housing portion 31a of the filter case 31 and the outer peripheral wall 33d of the spacer 33. The outer peripheral edge 34c of the outer filter 34 is airtightly held in the thickness direction by the outer peripheral wall 35c of the cover 35 and the outer peripheral wall 33d of the spacer 33. Therefore, air can pass through the sealed space S only through the inner surface 34b of the outer filter 34 or the outer surface 32a of the inner filter 32, except for the opening 16a of the cleaning pipe 16. In this disclosure, the sealed space S refers to a space that is not completely airtight, but allows air to enter and exit only through a path that ensures dustproofness.

[0046] 6 to 8, a connecting pipe portion 33e in the shape of a circular hole is provided in front of the outer peripheral wall 33d of the spacer 33, penetrating the outer peripheral wall 33d in the front-to-rear direction. The cleaning pipe 16 is inserted into the connecting pipe portion 33e. The opening 16a of the cleaning pipe 16 extends radially inward from the connecting pipe portion 33e. The opening 16a of the cleaning pipe 16 opens along the outer surface 32a of the inner filter 32 and the inner surface 34b of the outer filter 34 in the sealed space S between the inner filter 32 and the outer filter 34. In this disclosure, the opening 16a of the cleaning pipe 16 corresponds to a cleaning intake port through which compressed air is supplied.

[0047] As shown in Figures 5 to 9, a cover 35 is provided on the outside (left side) of the outer surface 34a of the outer filter 34. The cover 35 is disk-shaped with a diameter slightly larger than that of the outer filter 34. The cover 35 covers the entire outer surface 34a of the outer filter 34 from the left. A circular insertion hole 35b is provided in the center of the cover 35, penetrating in the left-right direction and through which the output shaft 21c is inserted. The cover 35 has multiple beam portions 35g that extend linearly in the radial direction or in an arc shape in the circumferential direction. A multiple cleaning outlet 35a that penetrates the cover 35 in the left-right direction is formed between the multiple beam portions 35g. The multiple cleaning outlets 35a also serve as inlets for introducing outside air into the inside of the cover 35.

[0048] 6 and 7 , the cover 35 has an annular center rib 35e that protrudes to the right, radially surrounds the insertion hole 35b, and extends to the right. At four equal circumferential positions of the center rib 35e, protruding portions 35f are provided, which protrude radially outward in semicircular arcs from the center rib 35e. At four equal circumferential positions of the cover 35, four cylindrical portions 35i are provided, which protrude to the right. The cylindrical portions 35i and the protruding portions 35f are alternately arranged at approximately 45° intervals around the circumferential direction of the cover 35. A circular insertion hole 35j is provided at the center of each cylindrical portion 35i, through which the boss portion 31g of the filter case 31 is inserted. The four boss portions 31g of the filter case 31 are inserted through the insertion holes 32e of the inner filter 32, the insertion holes 33j of the spacer 33, the insertion holes 34e of the outer filter 34, and the insertion holes 35j of the cover 35, and the fixing screws 36 are fastened to the female threads 31h. As a result, the inner filter 32, the spacer 33, and the outer filter 34 are sandwiched between the cover 35 and the filter case 31, and are held so as not to move left and right or rotate in the circumferential direction.

[0049] As shown in Figures 8 and 9, the cover 35 is provided with a retaining rib (outer rib) 35h that protrudes to the right. The retaining rib 35h is provided on the right portion of the outer peripheral wall 35c of the cover 35, the right portion of the center rib 35e, and the like. The retaining rib 35h abuts against the outer surface 34a of the outer filter 34 to hold the outer filter 34. Furthermore, a spacer beam portion (inner rib) 33g is provided at a position opposite the retaining rib 35h in the left-right direction, with the outer filter 34 sandwiched therebetween. By sandwiching the outer filter 34 between the retaining rib 35h and the beam portion 33g, movement of the outer filter 34 relative to the cover 35 and the spacer 33 is restricted.

[0050] 6 to 8 and 10, a circular hole-shaped connecting pipe 35d penetrating the outer peripheral wall 35c in the front-rear direction is provided in the front portion of the outer peripheral wall 35c of the cover 35. The cleaning pipe 16 is inserted through the connecting pipe 35d. The cleaning pipe 16 is also inserted through the connecting pipe 33e of the spacer 33 arranged radially inward of the connecting pipe 35d.

[0051] Referring to Figure 9, the intake flow path W1 through which outside air is introduced from the intake section 30 will be described. First, the motor 21 is driven to create a negative pressure inside the crankcase 20 (see Figure 5). Outside air is introduced inside the cover 35 from the cleaning outlet 35a of the cover 35. The outside air flows from the outer surface 34a of the outer filter 34 to the inner surface 34b while being filtered through the interior. The outside air flows through the sealed space S between the outer filter 34 and the inner filter 32. The outside air flows from the outer surface 32a of the inner filter 32 to the inner surface 32b while being filtered through the interior. The filtered outside air flows into the crankcase 20 from the intake port 31b of the filter case 31.

[0052] The cleaning flow path W2, which blows away dust accumulated on the outer filter 34 or the inner filter 32 (see Figure 9), will be described with reference to Figure 10. First, the pressure inside the tank 2 drops to a predetermined level and compressed air is discharged from the valve 15 to the cleaning pipe 16 (see Figure 3). Compressed air is supplied from the opening (cleaning intake port) 16a of the cleaning pipe 16 to the sealed space S between the inner filter 32 and the outer filter 34.

[0053] The compressed air flows approximately parallel to the outer surface 32a of the inner filter 32 and the inner surface 34b of the outer filter 34. To escape from the sealed space S, the compressed air must pass through either the inner filter 32 or the outer filter 34. Because the outer filter 34 is designed to allow air to pass through more easily than the inner filter 32, the compressed air flows from the inner surface 34b of the outer filter 34 to the outer surface 34a. This causes dust accumulated on the outer surface 34a and inside the outer filter 34 to be blown outward (to the left) from the outer filter 34. The compressed air flowing approximately parallel to the outer surface 32a of the inner filter 32 also blows away dust accumulated on the outer surface 32a. The dust blown away at this time is also blown outward from the outer filter 34. The dust is then discharged to the outside through the cleaning outlet 35a of the cover 35. In this way, dust accumulated around the inner filter 32 and the outer filter 34 is quickly removed.

[0054] As described above, the air compressor 1 has an inner filter 32 that covers the air intake port 31b as shown in Figures 6 and 7. The air compressor 1 has an outer filter 34 that covers the inner filter 32 from the outside and through which air passes more easily than the inner filter 32. The air compressor 1 has a cleaning pipe 16 that extends from a tank 2 (see Figure 2) that stores compressed air. The air compressor 1 has a cleaning intake port 16a that is connected to the cleaning pipe 16 and introduces compressed air between the inner filter 32 and the outer filter 34.

[0055] Therefore, by providing the inner filter 32 and outer filter 34, it is possible to prevent dust from entering the crankcase 20 and to suppress noise leakage from within the crankcase 20. Furthermore, compressed air is introduced from the tank 2 into the area between the inner filter 32 and the outer filter 34 via the cleaning pipe 16 and the cleaning intake port 16a. This allows compressed air to flow from the inner surface 34b of the outer filter 34 to the outer surface 34a, blowing accumulated dust outward. Moreover, even if the air compressor 1 is not connected to a power source, compressed air can be introduced from the tank 2 into the cleaning intake port 16a mechanically or manually by connecting a valve, cock, or the like to the cleaning pipe 16. In this way, dust accumulated on the outer surface 34a or inside of the outer filter 34 or on the outer surface 32a of the inner filter 32 can be efficiently removed.

[0056] 6 to 9, the outer filter 34 is thinner than the inner filter 32. Therefore, even if the air pressure of the compressed air introduced into the cleaning intake port 16a is sufficiently lower than that of the compressed air inside the tank 2 (see FIG. 2), dust can be blown and removed from the inner surface 34b side of the outer filter 34 to the outer surface 34a side. The dustproofness and soundproofing properties of the crankcase 20 can be maintained by making the inner filter 32 thicker than the outer filter 34.

[0057] 6 to 9, the outer filter 34 has a coarser mesh than the inner filter 32. Therefore, even if the air pressure of the compressed air introduced into the cleaning intake port 16a is sufficiently lower than that of the compressed air inside the tank 2 (see FIG. 2), dust can be blown and removed from the inner surface 34b of the outer filter 34 to the outer surface 34a. The dustproofness and soundproofing properties of the crankcase 20 can be maintained by making the inner filter 32 finer than the outer filter 34.

[0058] 8 and 9, a sealed space S into which compressed cleaning air is introduced is formed between the inner filter 32 and the outer filter 34. Therefore, the compressed air sent from the cleaning intake port 16a temporarily accumulates in the sealed space S between the inner filter 32 and the outer filter 34. The compressed air that does not fit into the sealed space S flows toward the outer surface 34a of the outer filter 34. Therefore, by guiding the path of the compressed air toward the outer surface 34a of the outer filter 34, dust can be removed more efficiently.

[0059] 6 to 9, a spacer 33 is provided between the inner filter 32 and the outer filter 34. This prevents the outer surface 34a of the inner filter 32 from coming into close contact with the inner surface 34b of the outer filter 34. This maintains a sealed space S through which compressed air flows between the inner filter 32 and the outer filter 34. This allows dust to be removed by compressed air from the inner filter 32, the outer filter 34, or the area between both filters.

[0060] 8 and 9, the spacer 33 has an outer peripheral wall 33d that covers the outer peripheral edge 32c of the inner filter 32 and the outer peripheral edge 34c of the outer filter 34. Therefore, the outer peripheral wall 33d of the spacer 33 can airtightly seal the outer peripheral edge 32c of the inner filter 32 and the outer peripheral edge 34c of the outer filter 34. This improves the dustproofness and soundproofing of the crankcase 20.

[0061] As shown in Figures 8 and 9, the air compressor 1 has a cover 35 that covers the outer filter 34 from the outside. The cover 35 has retaining ribs (external ribs) 35h that retain the outer surface 34a of the outer filter 34. The spacer 33 has beams (internal ribs) 33g that retain the inner surface 34b of the outer filter 34 at positions corresponding to the retaining ribs 35h. Therefore, the retaining ribs 35h and the beams 33g face each other, preventing the outer filter 34 from moving. This prevents the outer filter 34 from shifting position due to compressed air. This prevents gaps around the outer filter 34 that allow dust to enter.

[0062] 6 to 9, the air compressor 1 has a cover 35 that covers the outer filter 34 from the outside. The cover 35 has a connecting pipe portion 35d that connects the cleaning pipe 16 so as to open between the inner filter 32 and the outer filter 34. Therefore, compressed air can be introduced between the inner filter 32 and the outer filter 34 while preventing dust from accidentally entering between the inner filter 32 and the outer filter 34.

[0063] As shown in Figure 8, the cleaning intake port 16a opens along the outer surface 32a of the inner filter 32 and the inner surface 34b of the outer filter 34. This allows compressed air to flow along the outer surface 32a of the inner filter 32 and the inner surface 34b of the outer filter 34. This more reliably blows away dust that has accumulated on the outer surface 34a or inside of the outer filter 34, or on the outer surface 32a of the inner filter 32. It also prevents dust from entering the interior of the inner filter 32 from the outer surface 32a.

[0064] As shown in Figure 8, the opening of the cleaning pipe 16 is the cleaning intake port 16a. Therefore, compressed air with a relatively high air pressure coming out of the opening of the cleaning pipe 16 can flow between the inner filter 32 and the outer filter 34. This allows dust accumulated on the inner filter 32 or the outer filter 34 to be blown away with great force.

[0065] Various modifications can be made to the above-described embodiment of the present disclosure. For example, in this embodiment, the intake unit 30 is provided on the left side of the main body 10, and the inner filter 32 and the outer filter 34 are held in a position in which they extend in the vertical direction. Alternatively, the intake unit 30 may be provided on the lower part of the main body 10, and the inner filter 32 and the outer filter 34 may be held in a position in which they extend in the approximately horizontal direction.

[0066] In the illustrated example, the valve 15 sends compressed air stored in the valve 15 to the intake section 30 via the cleaning pipe 16 when, for example, the air compressor 1 is stopped and the pressure in the tank 2 falls below a predetermined value. Alternatively, for example, compressed air may not be stored in the valve 15, and compressed air may be sent from the tank 2 to the intake section 30 via the valve 15 and the cleaning pipe 16 when the pressure in the tank 2 meets a predetermined condition. The pressure at which the valve 15 operates is not limited to the illustrated value and may be changed as appropriate. Furthermore, instead of the valve 15, the compressed air in the tank 2 may be sent to the intake section 30 using, for example, a manually openable cock. In this case, the inner filter 32 and the outer filter 34 can also be cleaned even when the power to the air compressor 1 is turned off.

[0067] Although a two-layer structure consisting of an inner filter 32 and an outer filter 34 is used, the present invention can also be applied to a structure having three or more layers of filters. The thickness, mesh size, density (number of fibers per unit area at the same thickness), material, etc. of the inner filter 32 and the outer filter 34 may be changed as appropriate as long as the outer filter 34 satisfies the condition that air passes through more easily than the inner filter 32. The ease of air passing through the inner filter 32 and the outer filter 34 can be determined, for example, by the kinematic viscosity per unit area ((cm 3 / sec) / cm 2 ) can also be used for comparison. [Explanation of symbols]

[0068] 1...Air compressor 2...Tank, 2a...Leg, 2b...Side protector 3...base part, 3a...handle 4...Main body cover, 4a...Ventilation hole, 4b...Operation panel 5...Discharge port (for low pressure), 5a...Adjustment dial 6...Discharge port (for high pressure), 6a...Adjustment dial 7...Drain discharge device, 7a...Drain cock, 7b...Drain discharge pipe 10...Main body 11...first compression section, 11a...first cylinder, 11b...first piston, 11c...first rod 11d...first compression chamber, 11e...check valve 12... second compression section, 12a... second cylinder, 12b... second piston, 12c... second rod 12d...second compression chamber, 12e...check valve 13...Communication pipe 14...supply pipe, 14a...branch pipe 15...Valve 16...Cleaning pipe, 16a...Opening (cleaning intake) 20... crankcase, 20a... opening 21...motor, 21a...rotor, 21b...stator, 21c...output shaft 21d, 21e... bearing, 21f... restricting plate 22, 23...Cooling fan 24...1st crank 25...Second crank 30...Intake section 31...Filter case (crankcase cover) 31a...filter housing portion, 31b...air intake port, 31c...projection portion, 31d...insertion hole 31e...protrusion, 31f...screw hole, 31g...boss, 31h...female thread 32...inner filter, 32a...outer surface, 32b...inner surface, 32c...outer rim 32d, 32e...through holes, 32f...recess 33...spacer, 33a...ventilation hole, 33b...through hole, 33c...recess, 33d...outer peripheral wall 33e...connecting pipe portion, 33f...beam portion, 33g...beam portion (inner rib), 33h...retaining rib 33i... cylindrical portion, 33j... insertion hole 34...outer filter, 34a...outer surface, 34b...inner surface, 34c...outer rim 34d, 34e...through holes, 34f...recess 35...cover, 35a...cleaning outlet (inlet), 35b...through hole 35c...outer peripheral wall, 35d...connecting pipe section, 35e...center side rib, 35f...overhanging section 35g...Beam portion, 35h...Retaining rib (outer rib), 35i...Cylindrical portion, 35j...Through hole 36, 37...Fixing screws J…Output axis line W1: Inlet flow path, W2: Cleaning flow path S…Sealed space

Claims

1. An air compressor, An inner filter that covers the air intake, an outer filter that covers the inner filter from the outside and allows air to pass through more easily than the inner filter; a cleaning pipe extending from a tank storing compressed air; an air compressor having a cleaning intake port connected to the cleaning pipe for introducing compressed air between the inner filter and the outer filter;

2. 2. The air compressor of claim 1, The outer filter is thinner than the inner filter of the air compressor.

3. 3. The air compressor according to claim 1 or 2, An air compressor in which the outer filter has a coarser mesh than the inner filter.

4. The air compressor according to any one of claims 1 to 3, An air compressor in which a sealed space into which compressed air for cleaning is introduced is formed between the inner filter and the outer filter.

5. An air compressor according to any one of claims 1 to 4, An air compressor in which a spacer is provided between the inner filter and the outer filter.

6. 6. The air compressor according to claim 5, The spacer has an outer wall that covers the outer peripheral edge of the inner filter and the outer peripheral edge of the outer filter.

7. 7. The air compressor according to claim 5 or 6, a cover that covers the outer filter from the outside, The cover has an outer rib that holds the outer surface of the outer filter. The spacer has inner ribs that hold the inner surface of the outer filter at positions corresponding to the outer ribs.

8. An air compressor according to any one of claims 1 to 7, a cover that covers the outer filter from the outside, The cover has a connecting pipe portion that connects the cleaning pipe so that it opens between the inner filter and the outer filter.

9. An air compressor according to any one of claims 1 to 8, The cleaning air intake port is an air compressor that opens along the outer surface of the inner filter and the inner surface of the outer filter.

10. An air compressor according to any one of claims 1 to 9, An air compressor in which the opening of the cleaning pipe is the cleaning intake port.

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