US20130209287A1

US20130209287A1 - Air compressor

Info

Publication number: US20130209287A1
Application number: US13/760,615
Authority: US
Inventors: Kenji Kobori; Shinichiro Sato
Original assignee: Hitachi Koki Co Ltd
Current assignee: Koki Holdings Co Ltd
Priority date: 2012-02-09
Filing date: 2013-02-06
Publication date: 2013-08-15
Also published as: JP2013163981A; CN203516007U

Abstract

An air compressor including: a motor; a compression mechanism that is configured to be driven by the motor; a tank unit that includes an air tank configured to store therein compressed air generated by the compression mechanism and to which the motor is fixed; an elastic member via which the compression mechanism is coupled to the tank unit; and a rotation transfer member that is configured to transfer a rotational force of the motor to the compression mechanism even when a shaft center of a rotary shaft of the motor and a shaft center of a rotary shaft of the compression mechanism deviate from each other.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from Japanese Patent Application No. 2012-026117 filed on Feb. 9, 2012, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The invention relates to an air compressor generating compressed air that is necessary for driving an air tool such as nailing machine.

BACKGROUND

In building sites and the like, an air tool is widely used which drives a nail or screw into wood and the like by a pressure of compressed air. In general, an air compressor that drives the air tool and the like is configured so that rotation movement of a rotary output shaft of a driving unit such as motor is converted into reciprocating movement of a piston in a cylinder through a crankshaft of a compressed air generation unit and the air sucked through a suction valve of the cylinder is compressed by the reciprocating movement of the piston. The compressed air compressed in the cylinder is discharged from an exhaust valve of the cylinder to an air tank through a pipe and is stored in the air tank. Also, when compressing the air to a high pressure, a multistage reciprocating compressor that increases a pressure in stages is generally used. The air compressor is disclosed in JP-A-2009-185648, for example.
JP-A-2009-185648 discloses a structure where “a compression unit 5 is coupled to one end side of a motor housing of a motor unit 2 via a stator holder 23 and the compression unit 3 is fixed onto a frame 9 connecting air tanks 4 a, 4 b by a bolt” (refer to paragraph [0044] and FIG. 2 of JP-A-2009-185648). In this case, since the motor unit 2 and the compression unit 3 are integrated and fixed to the frame 9, a mass of a vibrating part (vibration source) is increased.
In the above-described air compressor, the air compressor body is highly vibrated by vibration caused due to the reciprocating movement of the piston. Also, a “positional deviation phenomenon” in which an installation position is moved little by little due to the vibration of the air compressor body may occur depending on installation states on a floor. Here, when a weight of the air compressor body is increased, it is possible to expect that the vibration will be reduced. However, since the air compressor is carried by a hand and is used in various fields, the body is made to be small and light as much as possible. Thus, it is preferable to avoid increasing the weight.

SUMMARY

The invention has been made to solve the above problem. An object of the invention is to provide an air compressor capable of reducing vibration accompanied by an operation, compared to the conventional configuration, while avoiding increase of a body weight.
According to an aspect of the present invention, there is provided an air compressor including: a motor; a compression mechanism that is configured to be driven by the motor; a tank unit that includes an air tank configured to store therein compressed air generated by the compression mechanism and to which the motor is fixed; an elastic member via which the compression mechanism is coupled to the tank unit; and a rotation transfer member that is configured to transfer a rotational force of the motor to the compression mechanism even when a shaft center of a rotary shaft of the motor and a shaft center of a rotary shaft of the compression mechanism deviate from each other.
Any combination of the above-described elements and the conversion of the invention into a method, a system and the like are also effective as the aspects of the invention.
According to the invention, the motor is fixed to the tank unit without via the compression mechanism. Therefore, compared to a configuration where the motor and the compression mechanism are integrated and the compression mechanism is fixed to the tank unit, it is possible to reduce the vibration accompanied by the operation while avoiding the increase of the body weight.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of an air compressor 1 according to an illustrative embodiment of the invention;

FIG. 2 is a sectional plan view (a cover 15 is not shown) showing a motor 2 and a compression mechanism unit 3 of the air compressor 1 shown in FIG. 1; and

FIG. 3 is a sectional front view (a cover 15 is not shown) in which a part of the air compressor 1 shown in FIG. 1 is fracture-shown.

DETAILED DESCRIPTION

Hereinafter, a preferred embodiment of the invention will be specifically described with reference to the accompanying drawings. In the meantime, the same or equivalent elements, members and the like shown in the drawings are indicated with the same reference numerals and the overlapping descriptions are appropriately omitted. Also, the illustrative embodiment does not limit the invention and is just exemplary. It cannot be said that all features and combinations thereof described in the illustrative embodiment are essentials of the invention.
FIG. 1 is a perspective view of an air compressor 1 according to an illustrative embodiment of the invention. FIG. 2 is a sectional plan view showing a motor 2 and a compression mechanism unit 3 of the air compressor 1. FIG. 3 is a sectional front view in which a part of the air compressor 1 is fracture-shown. In FIGS. 2 and 3, a cover 15 is not shown.
As shown in FIG. 1, an air compressor 1 has a structure where a cover 15 covers a tank unit 4 including a pair of air tanks 41 storing therein compressed air. Rubber foot 7 for vibration-proof and support, which contact a bottom surface, are integrated with the tank unit 4, and handles 6 for conveyance are provided to stand from the tank unit 4. As shown in FIGS. 2 and 3, the air compressor 1 has a motor 2 that is a driving source, a compression mechanism unit 3 that is driven by the motor 2 and generates compressed air and a control circuit unit 5 that controls an operation of the motor 2, inside the cover 15. An operator operates a power supply switch 8 exposed from the cover 15, thereby turning on/off commercial alternating-current (AC) power that is fed to the air compressor 1 through a power supply cord 9 (refer to FIG. 3). Driving power for the control circuit unit 5, the motor 2 and the like is fed through the power supply switch 8.
The motor 2 has a rotor 21, a stator 22 and a driving shaft 23 and a rotation operation thereof is controlled by the control circuit unit 5. One end of the driving shaft 23 is provided with a cooling fan 24. The fan 24 is surrounded by a fan guide 25. In the meantime, the other end of the driving shaft 23 is elastically coupled to a crankshaft 32 of the compression mechanism unit 3 so that rotation can be transferred thereto, via a flexible coupling 26 (which is made of a resin or steel material, for example) having elasticity or flexibility and serving as the rotation transfer member. According a related-art configuration, the motor 2 has been integrally fixed to the compression mechanism unit. However, in this illustrative embodiment, the motor 2 is separated from the compression mechanism unit 3 and is fixed to a frame 42 a, which connects two air tanks 41 of the tank unit 4, by a fastener 45 (fitting) such as bolt. Regarding the fixing, an elastic member is not used.
The compression mechanism unit 3 is a two-stage reciprocating compression mechanism and includes a crank case 31, the crankshaft 32, a high pressure-side connecting rod 34 a having a high pressure-side piston 33 a, a low pressure-side connecting rod 34 b having a low pressure-side piston 33 b, a high pressure-side cylinder 35 a and a low pressure-side cylinder 35 b. The high pressure-side piston 33 a and the high pressure-side cylinder 35 a configure a high pressure-side compression chamber 36 a and the low pressure-side piston 33 b and the low pressure-side cylinder 35 b configure a low pressure-side compression chamber 36 b. In the high pressure-side connecting rod 34 a and low pressure-side connecting rod 34 b, a high pressure-side crank arm 37 a and a low pressure-side crank arm 37 b are respectively provided via bearings 38. The high pressure-side crank arm 37 a and the low pressure-side crank arm 37 b are eccentrically attached to the crankshaft 32 and convert rotation movement of the crankshaft 32 into reciprocating movements of the high pressure-side piston 33 a and low pressure-side piston 33 b. Also, the crankshaft 32 is provided with a balancer 39 (flywheel) for offsetting unbalanced load of the crank arm or piston. The compression mechanism unit 3 is elastically coupled to a frame 42 b, which connects two air tanks 41 of the tank unit 4, via an elastic member 43 by a fastener 44 (fitting) such as bolt.
The tank unit 4 storing the compressed air has the air tanks 41 that are a pair of cylindrical tanks arranged in parallel, for example, and are connected by the frames 42 a, 42 b (which are welding-fixed to the air tanks 41, for example). The tank unit 4 is connected to the compression mechanism unit 3 by a piping 10. The piping 10 is a flexible tube (which is made of resin or metal, for example) having elasticity, for example. Also, a safety valve (not shown) is attached to a part of the tank unit 4. When a pressure in the tank unit 4 is abnormally increased, the safety valve enables a portion of the compressed air to be discharged to the outside, thereby preventing the abnormal pressure increase.
The tank unit 4 is provided with a pair of compressed air outlets 11. An air tool (not shown) such as a nailing machine is coupled to each of the outlets 11 through a hose. A decompression valve 12 is provided between the outlets 11 and the tank unit 4, respectively, and has a function of reducing a pressure in the tank unit 4 to a pressure appropriate for driving of the air tool. Therefore, the outlet 11 is provided with the compressed air having an allowed maximum pressure of the air tank 41 or lower, irrespective of the pressure in the tank unit 4. A pressure gauge 13 is attached in the vicinity of the outlets 11 and is configured to monitor the pressure that is discharged from the outlets 11.
Hereinafter, a process of generating the compressed air by the air compressor 1 is schematically described.
The rotation movement of the motor 2 is transferred to the crankshaft 32 through the driving shaft 23 and the flexible coupling 26, thereby rotating the high pressure-side crank arm 37 a and the low pressure-side crank arm 37 b. An outer periphery of the high pressure-side crank arm 37 a is rotatably provided with the high pressure-side connecting rod 34 a via the bearing 38 and the high pressure-side crank arm 37 a is eccentrically rotated, so that the rotation movement is converted into the reciprocating movement of the high pressure-side piston 33 a inscribed in the high pressure-side cylinder 35 a. Likewise, an outer periphery of the low pressure-side crank arm 37 b is rotatably provided with the low pressure-side connecting rod 34 b via the bearing 38 and the low pressure-side crank arm 37 b is eccentrically rotated, so that the rotation movement is converted into the reciprocating movement of the low pressure-side piston 33 b inscribed in the low pressure-side cylinder 35 b.
Upper walls of the high pressure-side compression chamber 36 a and the low pressure-side compression chamber 36 b are provided with a suction valve (not shown) for external air and a discharge valve (not shown) for compressed air, so that a function serving as a check valve enabling the air to be supplied only in one direction is provided. First, in a suction process during which the high pressure-side piston 33 a and the low pressure-side piston 33 b move downward from a top dead center to a bottom dead center in the high pressure-side cylinder 35 a and the low pressure-side cylinder 35 b, the external air is sucked into the high pressure-side compression chamber 36 a and the low pressure-side compression chamber 36 b. On the other hand, in a compression process during which the high pressure-side piston 33 a and the low pressure-side piston 33 b move upward from the bottom dead center to the top dead center in the high pressure-side cylinder 35 a and the low pressure-side cylinder 35 b, the high pressure-side piston 33 a and the low pressure-side piston 33 b compress the air in the high pressure-side compression chamber 36 a and the low pressure-side compression chamber 36 b, thereby generating the compressed air. Also, the compressed air, which is generated in a discharge process during which the high pressure-side piston 33 a and the low pressure-side piston 33 b reach the top dead centers of the high pressure-side compression chamber 36 a and the low pressure-side compression chamber 36 b, is discharged to the piping 10 communicating with the tank unit 4. The reciprocating movements of the high pressure-side piston 33 a and the low pressure-side piston 33 b are offset in phases, the compressed air discharged from the low pressure-side compression chamber 36 b is sucked into the high pressure-side compression chamber 36 a and the compressed air discharged from the high pressure-side compression chamber 36 a is supplied to the air tank 7 through the piping 10. The air compressed by the compression mechanism unit 3 is supplied from the discharge port thereof into the tank unit 4 through the piping 10. In the meantime, the supplied compressed air has a pressure of about 3.0 to 4.5 MPa in the tank unit 4.
By repeating the suction, compression and discharge processes by the reciprocating movements of the high pressure-side piston 33 a and the low pressure-side piston 33 b, the compressed air having an allowed maximum pressure can be supplied from the compression mechanism unit 3 to the tank unit 4.
The compression mechanism unit 3 is vibrated due to the reciprocating movements of the high pressure-side piston 33 a and the low pressure-side piston 33 b, and the vibration is transferred to the tank unit 4, so that the whole air compressor 1 is vibrated. In this illustrative embodiment, the motor 2 is separated from the compression mechanism unit 3, which is a larger vibration source than the motor, and is directly fixed to the tank unit 4. Accordingly, compared to a configuration where the motor 2 is integrated with the compression mechanism unit 3, the mass of the vibration source (part integrally vibrating with the compression mechanism unit 3) is reduced, and further, the mass and inertia moment of a part other than the vibration source or a part having relatively small vibration are increased due to the motor 2. Thus, the tank unit 4 is difficult to vibrate, so that it is possible to reduce the whole vibration of the air compressor 1. Also, the driving shaft 23 and the crankshaft 32 are elastically coupled using the flexible coupling 26. Therefore, it is possible to prevent the damages of the driving shaft 23 and the crankshaft 32, which are caused due to the center deviation upon assembling or by the vibration of the compression mechanism unit 3, so that it is possible to prolong the lifespan of the driving shaft and the crankshaft. Also, since the piping 10 connecting the compression mechanism unit 3 and the air tank 41 is made of the flexible tube having elasticity, for example, it is possible to prevent the damage of the piping 10 due to the vibration of the compression mechanism unit 3.
Although the invention has been described with reference to the illustrative embodiment, one skilled in the art can understand that the respective elements or respective processes of the illustrative embodiment can be variously modified within the scope defined in the claims. The modified embodiments are as follows. For example, the same effects can be obtained even when a universal joint as represented by a propeller shaft of a vehicle is used instead of the flexible coupling. Also, an elastic member may be provided between the motor 2 and the tank unit, for example.
The present invention provides illustrative, non-limiting aspects as follows:
(1) In a first aspect, there is provided an air compressor including: a motor; a compression mechanism that is configured to be driven by the motor; a tank unit that includes an air tank configured to store therein compressed air generated by the compression mechanism and to which the motor is fixed; an elastic member via which the compression mechanism is coupled to the tank unit; and a rotation transfer member that is configured to transfer a rotational force of the motor to the compression mechanism even when a shaft center of a rotary shaft of the motor and a shaft center of a rotary shaft of the compression mechanism deviate from each other.
(2) In a second aspect, there is provided the air compressor according to the first aspect, wherein the rotation transfer member is a flexible coupling or an universal joint.
(3) In a third aspect, there is provided the air compressor according to the first aspect or the second aspect, further comprising a piping unit configured to deliver the compressed air generated by the compression mechanism to the air tank, wherein the piping unit has elasticity.
(4) In a fourth aspect, there is provided the air compressor according to the third aspect, wherein the piping unit is a flexible tube.
(5) In a fifth aspect, there is provided the air compressor according to any one of the first to fourth aspects, wherein the motor is not directly coupled to the compression mechanism except for transferring of a driving force.
(6) In a sixth aspect, there is provided the air compressor according to any one of the first to fifth aspects, wherein the motor is fixed to the tank unit without via an elastic member.
(7) In a seventh aspect, there is provided the air compressor according to any one of the first to sixth aspects, wherein the tank unit includes a frame that supports the air tank, and the compression mechanism is coupled to the frame.
(8) In an eighth aspect, there is provided the air compressor according to any one of the first to seventh aspects, wherein the compression mechanism is a reciprocating compression mechanism.

Claims

1. An air compressor comprising:

a motor;

a compression mechanism that is configured to be driven by the motor;

a tank unit that includes an air tank configured to store therein compressed air generated by the compression mechanism and to which the motor is fixed;

an elastic member via which the compression mechanism is coupled to the tank unit; and

a rotation transfer member that is configured to transfer a rotational force of the motor to the compression mechanism even when a shaft center of a rotary shaft of the motor and a shaft center of a rotary shaft of the compression mechanism deviate from each other.

2. The air compressor according to claim 1,

wherein the rotation transfer member is a flexible coupling or an universal joint.

3. The air compressor according to claim 1, further comprising a piping unit configured to deliver the compressed air generated by the compression mechanism to the air tank,

wherein the piping unit has elasticity.

4. The air compressor according to claim 3,

wherein the piping unit is a flexible tube.

5. The air compressor according to claim 1,

wherein the motor is not directly coupled to the compression mechanism except for transferring of a driving force.

6. The air compressor according to claim 1,

wherein the motor is fixed to the tank unit without via an elastic member.

7. The air compressor according to claim 1,

wherein the tank unit includes a frame that supports the air tank, and the compression mechanism is coupled to the frame.

8. The air compressor according to claim 1,

wherein the compression mechanism is a reciprocating compression mechanism.