Patent Application
20230151803
This application claims the benefit of priority to Japanese Patent Application No. 2021-186204, filed on Nov. 16, 2021, the entire contents of which are hereby incorporated by reference.
The present disclosure relates to an air compressor for supplying compressed air to an air tool, such as a compressed air-driven nailer or an air duster.
A technique for an air compressor is described in Japanese Patent No. 5186799 (hereafter, Patent Literature 1). The air compressor includes a reciprocating compression assembly for producing compressed air. A known compression assembly converts rotational output from an electric motor with a crank assembly into reciprocation of a piston in a cylinder to produce compressed air. The compressed air produced in the compression assembly is stored into a tank. The compressed air stored in the tank is supplied to an air tool.
Outside air to produce such compressed air is drawn into a crankcase accommodating the crank assembly. Thus, a filter for reducing noise and dust is installed on an intake path for drawing outside air into the crankcase. With the technique in Patent Literature 1, the filter is attached to a crankcase cover that hermetically closes an end of the crankcase. The filter covers multiple inlets in the crankcase cover. The dust filter is held by a filter cover coupled to the crankcase cover. Outside air is then drawn into the inlets through a space between the peripheries of the filter cover and the crankcase cover. The intake path is thus bent, reducing noise resulting from external leakage of the operation noise of the compression assembly.
In addition to reducing noise, the air compressor is to protect the inside of the crankcase from dust. In particular, the air compressor with its intake path being protected from dust has higher maintainability and durability.
One or more aspects of the present disclosure are directed to a technique for improving the dustproof performance of an intake path to a crankcase.
A first aspect of the present disclosure provides an air compressor, including:
a compression assembly configured to reciprocate a piston in a cylinder to produce compressed air;
a crankcase accommodating the compression assembly and having an inner inlet to allow outside air to be drawn;
a filter located in the crankcase and covering the inner inlet from outside;
a filter cover having an outer inlet and covering the filter from outside; and
a dust cover covering the filter cover from outside, covering the outer inlet, and including an outer circumferential portion, the outer circumference portion and the filter cover having a space to draw outside air between the outer circumference portion and the filter cover.
The air compressor according to the above aspect of the present disclosure improves the dustproof performance of an intake path to the crankcase.
As shown in
The body cover 6 has two outlet ports 7 for high-pressure air on its front left surface. The body cover 6 has two outlet ports 8 for low-pressure air on its front right surface. Through the outlet ports 7 for high-pressure air, for example, compressed air of 2.5 MPa is supplied. Through the outlet ports 8 for low-pressure air, for example, compressed air of 1 MPa is supplied. Adjustment dials 7a and 8a are located above the outlet ports 7 and 8 to set their respective outlet pressures. The body cover 6 includes, on its upper front surface, an operation unit 9 operable for activation. The operation unit 9 includes various displays.
As shown in
The electric motor 22 is a brushless motor that produces relatively large activation torque. The electric motor 22 includes an annular rotor 22a and an annular stator 22b. The stator 22b is located inward from the circumference of the rotor 22a. The stator 22b is fixed to a right portion of the crankcase 21. A motor shaft 25 is coupled to the rotor 22a at the center. The motor shaft 25 has a right end receiving a heat-dissipating fan 23. The heat-dissipating fan 23 rotates to dissipate heat generated in the electric motor 22 and cool the electric motor 22. The motor shaft 25 extends leftward through the center of the stator 22b. The motor shaft 25 is rotatably supported across right and left portions of the crankcase 21 with a right bearing 25a and a left bearing 25b. The motor shaft 25 has a left end protruding leftward through an intake unit 30. The motor shaft 25 has the left end receiving an intake fan 24. The intake fan 24 rotates to blow outside air against the intake unit 30.
The cylindrical crankcase 21 includes a front portion coupled to a first cylinder 11a in the first compressor 11. The crankcase 21 includes a rear portion coupled to a second cylinder 12a in the second compressor 12. The internal space of the crankcase 21 allows passage of outside air.
The first cylinder 11a accommodates a first piston 11b to allow reciprocation in the front-rear direction. The first cylinder 11a extends frontward from the front portion of the crankcase 21. The first piston 11b is coupled to a first crank 26 in the motor shaft 25 with a first rod 11c.
The second cylinder 12a accommodates a second piston 12b to allow reciprocation in the front-rear direction. The second cylinder 12a extends rearward from the rear portion of the crankcase 21. The second piston 12b is coupled to a second crank 27 in the motor shaft 25 with a second rod 12c.
The first crank 26 and the second crank 27 are decentered in the same direction at the same position about the axis of the motor shaft 25. As the motor shaft 25 rotates once, one of the first compressor 11 and the second compressor 12 performs a compression process, and the other compressor performs an intake process at the same time. In the compression process in which the first piston 11b in the first compressor 11 moves forward, the second piston 12b in the second compressor 12 moves forward to perform the intake process. In the intake process in which the first piston 11b in the first compressor 11 moves backward, the second piston 12b in the second compressor 12 moves backward to perform the compression process.
The first cylinder 11a includes a first compression chamber 11d that connects to a second compression chamber 12d in the second cylinder 12a with a supply pipe 13. The supply pipe 13 has an upstream end connected to the first compression chamber 11d with an auxiliary check valve 11e. The auxiliary check valve 11e blocks compressed air without allowing flowing back from the supply pipe 13 into the first compression chamber 11d. The supply pipe 13 has a downstream end connected to the second compression chamber 12d. The compressed air flowing from the first compression chamber 11d through the auxiliary check valve 11e into the supply pipe 13 is directly supplied to the second compression chamber 12d.
In response to activation of the electric motor 22, compressed air is produced in two steps, which are through the first compressor 11 and the second compressor 12. The compressed air supplied to the second compression chamber 12d is compressed to a higher pressure in response to retraction of the second piston 12b. The high-pressure compressed air of, for example, about 4.5 MPa produced in the second compression chamber 12d flows into an air channel 15 extending to the tanks 2 through a first check valve 14. The first check valve 14 blocks the compressed air flowing into the air channel 15 without flowing back into the second compression chamber 12d.
The crankcase 21 is adjacent to the intake unit 30 on its left. Outside air is drawn into the crankcase 21 through the intake unit 30.
An example intake unit according to each of embodiments will be described.
The intake unit 30 in the first embodiment includes a crankcase cover 31, a filter 32, a filter cover 33, and a dust cover 34. The crankcase cover 31 hermetically covers an intake opening 21a of the crankcase 21. The filter 32 covers inner inlets 31e in the crankcase cover 31. The filter cover 33 covers the filter 32. The dust cover 34 covers the filter cover 33.
The opening 21a of the crankcase 21 is substantially circular. As shown in
As shown in
As shown in
As shown in
Each screw boss 31f protrudes leftward from the outer surface of the crankcase cover 31. Each screw boss 31f has a stepped outer diameter and includes a larger-diameter portion on its basal end and a smaller-diameter portion on its distal end. Each screw boss 31f has the inner inlets 31e on both sides. Eight inner inlets 31e are arranged in total in the present embodiment. The single filter 32 is accommodated in the filter-receiving recess 31b to cover the eight inner inlets 31e from outside.
The filter-receiving recess 31b is deep enough to accommodate the filter 32 substantially entirely in the thickness direction. Thus, as shown in
The filter 32 is a felt filter for reducing noise and dust. The filter 32 is substantially disk-shaped. The filter 32 has a through-hole 32a at its center. The protrusion 31c on the crankcase cover 31 extends through the through-hole 32a. The through-hole 32a has four through-holes 32b equally spaced on its periphery. Each threaded hole 31g in the crankcase cover 31 extends through the corresponding through-hole 32b. The through-hole 32a is surrounded by four through-holes 32c. The larger-diameter portion of each screw boss 31f in the crankcase cover 31 extends through the corresponding through-hole 32c.
The filter cover 33 is coupled to the outer surface of the filter 32. The filter cover 33 is a disk having substantially the same diameter as the filter 32. The filter cover 33 covers the entire outer surface of the filter 32. The filter cover 33 includes a cylindrical insertion portion 33a at its center. The insertion portion 33a receives the motor shaft 25 on its inner circumference.
As shown in
The filter cover 33 has multiple outer inlets 33d. As shown in
Each annular wall 33e enters a recess 34d on the dust cover 34 described later. As indicated by arrow W (intake path W) in
The filter cover 33 has four through-holes 33f equally spaced on its circumference. The smaller-diameter portion of each screw boss 31f in the crankcase cover 31 extends through the corresponding through-hole 33f As shown in
As shown in
The filter cover 33 includes an outer circumferential portion 33i having a uniform width and bent toward the filter 32 at an angle of substantially 45° along its entire circumference.
As shown in
As shown in
The dust cover 34 includes the four cylindrical protrusions 34b equally spaced in the circumferential direction on the inner surface. The protrusions 34b protrude toward the filter cover 33. The four protrusions 34b are received in the corresponding positioning recesses 33h on the filter cover 33. The dust cover 34 is thus positioned relative to the filter cover 33 in the direction of the motor axis J. In the positioning state, the dust cover 34 and the filter cover 33 have a space between them in the direction of the motor axis J. The space serves as the intake path W for drawing outside air into the crankcase 21.
Each protrusion 34b has a through-hole 34c at its center. Each through-hole 34c receives the corresponding fixing screw 37. As shown in
The dust cover 34 has multiple recesses 34d on the inner surface. The multiple recesses 34d are aligned with the annular walls 33e on the filter cover 33. Each recess 34d is circular and has a diameter large enough to receive the corresponding annular wall 33e. Each recess 34d is deep enough to receive the corresponding annular wall 33e with a narrow space left. The space between the bottom surface of each recess 34d and the corresponding annular wall 33e defines a part of the intake path W for drawing outside air.
Each annular wall 33e on the filter cover 33 enters (overlaps in the direction of the motor axis J) the corresponding recess 34d on the dust cover 34, thus bending the intake path W at substantially right angles. This defines the intake path W with a labyrinth structure.
The dust cover 34 includes an outer circumferential portion 34f having a uniform width and bent toward the filter cover 33 at an angle of substantially 45° along its entire circumference. As shown in
As shown in
In response to activation of the electric motor 22, the intake fan 24 rotates to blow outside air against the intake unit 30. As indicated by arrow Win
The outside air flowing into the space between the dust cover 34 and the filter cover 33 through the inlet port 38 is blown against the annular walls 33e on the filter cover 33 and flows into the recesses 34d on the dust cover 34. In this state, the flow of the outside air (intake path W) is bent at substantially right angles. After being bent at two positions on the intake path W, the outside air flowing into the recesses 34d flows into the outer inlets 33d (the inner circumferences of the annular walls 33e) and is blown against the filter 32.
The outside air passes through the filter 32 to filter dust. Clean outside air resulting from the dust filtering with the filter 32 flows into the crankcase 21 through the inner inlets 31e in the crankcase cover 31. Outside air flowing in through the intake path W is supplied to the first compressor 11. The outside air flowing in is supplied into the first cylinder 11a and compressed by the first piston 11b.
In the air compressor 1 according to the first embodiment, outside air flows into the outer inlets 33d through the inlet port 38 between the outer circumferential portion 34f of the dust cover 34 and the filter cover 33. Thus, the intake path W of the outside air extending in the plane direction of the filter cover 33 is bent in the thickness direction (the direction of the motor axis J) to reduce the likelihood that dust contained in the outside air is blown directly against the filter 32. The filter 32 is thus less likely to be clogged.
The path benders (annular walls 33e) are located between the filter cover 33 and the dust cover 34. The intake path W of the outside air passing between the filter cover 33 and the dust cover 34 is bent in the thickness direction of the filter cover 33 (the direction of the motor axis J). This reduces the likelihood that dust contained in the outside air is blown directly against the filter 32 and thus reduces clogging of the filter 32 more reliably.
Each path bender includes the annular wall 33e protruding from the circumference of the corresponding outer inlet 33d in the filter cover 33 toward the dust cover 34, and the recess 34d located on the dust cover 34 and receiving the annular wall 33e. Thus, the intake path W is bent in the thickness direction of the filter cover 33 reliably.
The dust cover 34 and the filter cover 33 are fastened together to the crankcase cover 31 with the fixing screws 37. This simplifies the connection of the dust cover 34 and the filter cover 33 to the crankcase cover 31 (crankcase 21).
The dust cover 34 has, on its outer surface, the indentations 34e accommodating the heads of the fixing screws 37. The dust cover 34 includes the protrusions 34b on the backs of the corresponding indentations 34e (on the inner surface). The protrusions 34b are received in the corresponding positioning recesses 33h on the filter cover 33. Thus, the dust cover 34 is positioned relative to the filter cover 33 about the motor axis J. The engagement of the protrusions 34b with the positioning recesses 33h positions the dust cover 34 relative to the filter cover 33. The dust cover 34 is thus attached easily.
The insertion portion 34a of the dust cover 34 receives the insertion portion 33a of the filter cover 33, and the filter cover 33 and the dust cover 34 are thus positioned relative to each other coaxially with the motor shaft 25. The insertion portion of the dust cover may be received on the inner circumference of the insertion portion of the filter cover.
Each outer inlet 33d is surrounded by the corresponding annular wall 33e and thus has a depth greater than the hole diameter. This prevents noise leakage in the crankcase 21, thus reducing noise in the compression assembly 10.
The first embodiment described above may be modified variously. For example, although each path bender includes the annular wall 33e on the filter cover 33 and the recess 34d on the dust cover 34 in the first embodiment, the recesses 34d on the dust cover 34 may be eliminated.
Although each annular wall 33e surrounds the corresponding outer inlet 33d in the filter cover 33, the dust cover 34 may include, for example, annular or curved walls protruding toward the outer inlets 33d as the path benders on the inner surface, instead of the annular walls 33e on the filter cover 33.
The inclination angles of the outer circumferential portion 33i of the filter cover 33 and the outer circumferential portion 34f of the dust cover 34 may be changed. One or both of the inclined outer circumferential portions 33i and 34f may be eliminated.
In the second embodiment, a dust cover 42 differs from the dust cover 34 in the first embodiment. The dust cover 42 in the present embodiment has a diameter larger than the dust cover 34 in the first embodiment. The dust cover 42 includes an outer circumferential portion 42a bent toward the crankcase 21 at substantially 90°. The outer circumferential portion 42a of the dust cover 42 covers outer circumferential portions of a filter cover 41 and the crankcase cover 31 laterally.
As shown in
In the second embodiment, the dust cover 42 includes multiple thick portions 42b on its outer surface. The thick portions 42b correspond to the recesses 34d (refer to
In the second embodiment, the air compressor 1 includes multiple path benders with a labyrinth structure having a locally narrowed space between the filter cover 41 and the dust cover 42 in addition to the path benders including the annular walls 41a on the filter cover 41 and the recesses 34d on the dust cover 42.
As shown in
In the second embodiment, the outer circumferential portion 42a of the dust cover 42 covers the outer circumferential portions of the filter cover 41 and the crankcase cover 31 laterally. Thus, when flowing into an inlet port 43 between the outer circumferential portion 42a of the dust cover 42 and the outer circumferential portion of the filter cover 41, outside air flows from the filter cover 41 toward the dust cover 42 (opposite to the flow direction in the outer inlets 33d). The intake path W of the outside air toward the dust cover 42 is thus bent in a plane direction of the filter cover 41. In the second embodiment, the outer circumferential portion 42a of the dust cover 42 bends the intake path W more reliably than the inlet port 38 in the first embodiment.
As shown in
Outside air is drawn through an inlet port 54 between the outer circumferential portion 52a of the dust cover 52 and a circumferential portion of the filter cover 51. The second filter 53 extends along the entire circumference of the inlet port 54.
In the third embodiment, the second filter 53 is installed between the filter cover 51 and the dust cover 52. This reduces clogging of the filter 32 still more reliably and also allows still less noise in the intake unit 50 (compression assembly 10).
The intake unit 60 has recesses 61c accommodating the heads of the fixing screws 37. The recesses 61c are shallower than the positioning recesses 33h in the first embodiment.
In the intake unit 60 in the present embodiment, the intake fan 24 rotates to blow outside air against the entire outer surface of the filter cover 61. The outside air is blown in a direction substantially along the motor axis J. Thus, although a portion of the outside air flows directly into the outer inlets 61b, the other portion of the outside air is mostly blown against the outer surface of the filter cover 61.
The outside air blown against the outer surface of the filter cover 61 flows along the outer surface and then is blown against the annular walls 61a to bend the intake path. The path benders remove dust from the outside air. The clean outside air with the dust removed flows into the outer inlets 61b.
Although the filter cover 61 is exposed, the annular walls 61a surrounding the corresponding outer inlets 61b serve as the path benders. This removes dust in the outside air effectively and reduces clogging of the filter 32.
The air compressor 1 according to any one of the first to fourth embodiments is an example of an air compressor in an aspect of the present disclosure. The compression assembly 10 in any one of the first to fourth embodiments is an example of a compression assembly in an aspect of the present disclosure. The crankcase 21 in any one of the first to fourth embodiments is an example of a crankcase in an aspect of the present disclosure. The inner inlets 31e in any one of the first to fourth embodiments each are an example of an inner inlet in an aspect of the present disclosure.
The filter 32 in any one of the first to fourth embodiments is an example of a filter in an aspect of the present disclosure. The filter cover 33 in the first embodiment, the filter cover 41 in the second embodiment, and the filter cover 51 in the third embodiment each are an example of a filter cover in an aspect of the present disclosure. The outer inlets 33d in the first embodiment and the outer inlets 33d in the second embodiment each are an example of an outer inlet in an aspect of the present disclosure.
The dust cover 34 in the first embodiment, the dust cover 42 in the second embodiment, and the dust cover 52 in the third embodiment each are an example of a dust cover in an aspect of the present disclosure. The outer circumferential portion 34f in the first embodiment, the outer circumferential portion 42a in the second embodiment, and the outer circumferential portion 52a in the third embodiment each are an example of an outer circumferential portion in an aspect of the present disclosure. The inlet port 38 in the first embodiment, the inlet port 43 in the second embodiment, and the inlet port 54 in the third embodiment each are an example of a space in an aspect of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-186204 | Nov 2021 | JP | national |
