Compressor

Abstract

A first tank, a main body of a compressor, an electric motor, and a second tank are combined to form a single assembly. A booster type air compressor as the single assembly including the first tank may be easily carried. The first tank at an inlet side is integrally combined to prevent a pulsation in the supplied compressed air for eliminating the drain contained in the compressed air. The air compressor, thus, is structured to discharge high compressed air from a high-pressure outlet joint formed on the second tank.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a compressor which boosts preliminary compressed fluid such as air so as to be stored as high compressed fluid in a tank.

2. Description of the Related Art

In a recent plant, a piping for supplying compressed air into a plant has been installed such that various pneumatic devices connected to the respective outlet joints of the piping may be operated. If the compressed air at the pressure higher than the one supplied from the piping in the plant is required, the compressor is connected to the outlet joint of the piping for further boosting the preliminarily compressed air supplied from the piping.

Japanese Unexamined Patent Application Publication No. 2007-51614 discloses a booster type compressor formed of a main body driven by an electric motor to suck air for recompression so as to discharge the resultant high compressed air, and a tank which stores the high compressed air discharged from the main body of the compressor.

The employed booster type compressor in general has the main body directly connected to the piping in the plant. As the other plural pneumatic devices are connected to the piping in the plant, the compressed air may cause pulsation depending on the state in the usage. The compressed air inside the piping of the plant may form drain owing to the change in the pressure or the temperature.

When the booster type compressor is installed in the piping of the plant, an inlet tank is required to be provided between the piping in the plant and the main body of the compressor so as to prevent pulsation in the compressed air supplied and to discharge the drain.

In the aforementioned case, the space for setting the additional inlet tank separately from the compressor is required, thus increasing as the cost for setting the tank and the piping. When the booster type compressor is used in the other place, both the compressor and the inlet tank have to be moved, resulting in large labor and considerable time required for laying out those devices.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a compressor which may be easily installed in a small space without preparing an additional inlet tank.

The present invention provides a compressor which includes a first tank connected to an external compressed fluid source for accommodating an inflow of a low compressed fluid from the external compressed fluid source, a main body of the compressor for sucking the low compressed fluid from the first tank so as to be compressed, and a second tank for storing a high compressed fluid compressed by the main body of the compressor, and for discharging the stored high compressed fluid to outside with a high-pressure outlet joint. The first tank, the main body of the compressor, and the second tank are combined to form a single assembly.

The first tank may be provided with a low-pressure outlet joint for discharging the low compressed fluid contained in the first tank.

The first inflow pressure control valve may be provided between the compressed fluid source and the first tank for regulating the inflow of the compressed fluid at a pressure in excess of a specified pressure into the first tank.

A second inflow pressure control valve may be provided between the first tank and the main body of the compressor for regulating the inflow of the compressed fluid at a pressure in excess of a specified pressure from the first tank to the main body.

The first tank may be provided with a relief valve which releases the compressed fluid to outside when a pressure within the first tank exceeds a set pressure.

A path extending from the external compressed fluid source to the main body of the compressor is provided with a filter for eliminating dust contained in the compressed fluid.

The first tank and the second tank have cylindrical bodies in parallel with each other in a longitudinal direction, and are horizontally installed with respect to a mount surface.

The first tank and the second tank may have cylindrical bodies in parallel with each other in a longitudinal direction, and vertically installed on a mount surface.

The first tank and the second tank may be provided with a gap therebetween. The main body of the compressor may be interposed between the first tank and the second tank so as to be partially fit in the gap.

Each of the first tank and the second tank may be provided with a drain valve for discharging a drain.

The structure may be provided with a communication pipe for allowing the first tank and the second tank to communicate with each other, wherein the communication pipe is provided with a check valve which allows the compressed fluid to flow from the first tank to the second tank but blocks an inverse flow.

The structure may be provided with an intake switching valve provided between the first tank and the main body, wherein the intake switching valve allows the main body to suck an external air upon its start-up and switches to a state where the main body sucks the compressed fluid from the first tank when a pressure within the second tank reaches a set pressure.

In the structure, the single assembly formed by combining the first tank, the main body of the compressor, and the second tank may be provided with handgrips at both ends of cylindrical bodies of the tanks such that the assembly is gripped.

The first tank, the main body, and the second tank may be stored in a case.

According to an embodiment of the present invention, the compressor as a single unit may be easily carried to the other place, and set in a small space requiring less time and labor. The booster compressor may be set in various places for supplying the high compressed fluid.

According to an embodiment, as the first tank is provided with the low-pressure outlet joint, the low compressed fluid stored in the first tank may be discharged from the low-pressure outlet joint. This allows the single compressor to supply the high compressed fluid and the low compressed fluid.

According to an embodiment of the present invention, a first inflow pressure control valve for regulating an inflow of the compressed fluid at the pressure in excess of the specified pressure into the first tank is provided between the compressed fluid source and the first tank. Even if the pressure at the side of the compressed fluid source varies, the first inflow pressure control valve allows the pressure within the first tank to be suppressed within a specified pressure range. This makes it possible to form the first tank using the inexpensive material and parts for the low pressure specification without employing the material that resists the high pressure, or the special parts.

According to an embodiment of the present invention, the second inflow pressure control valve for regulating the inflow of the compressed fluid at the pressure in excess of the specified pressure into the main body of the compressor from the first tank is provided between the first tank and the main body of the compressor. This makes it possible to prevent the compressed fluid at the pressure equal to or higher than the specified pressure from flowing into the main body of the compressor, thus keeping the main body of the compressor from damage.

According to an embodiment of the present invention, the first tank is provided with a relief valve which releases the compressed fluid contained within the first tank at the pressure in excess of the set pressure to outside. This makes it possible to prevent the inner pressure within the first tank from becoming equal to or higher than the specified pressure.

According to an embodiment of the present invention, a path extending from the external compressed fluid source to the main body of the compressor is provided with a filter for eliminating dust contained in the compressed fluid. So the dust contained in the compressed fluid supplied from the compressed fluid source may be eliminated by the filter, thus preventing reduction in the life of the main body of the compressor owing to the intake dust.

According to an embodiment of the present invention, the first and the second tanks have the cylindrical bodies in parallel with each other in a longitudinal direction, and are horizontally installed with respect to a mount surface, thus suppressing the height of the compressor to be low.

According to an embodiment of the present invention, the first and the second tank have the cylindrical bodies in parallel with each other in a longitudinal direction, and installed vertically on the mount surface, thus reducing the required space for setting.

According to an embodiment of the present invention, the first and the second tanks are arranged having a gap therebetween, and the main body of the compressor is provided between the first and the second tanks so as to be partially accommodated in the gap therebetween. This makes it possible to integrally form the compressor with low height, thus realizing the compact structure.

According to an embodiment of the present invention, each of the first and the second tanks is provided with a drain valve for discharging the drain. The drain valve is opened to discharge the drain within the tank.

According to an embodiment of the present invention, a communication pipe is provided for communicating the first and the second tanks. The communication pipe is provided with a check valve which allows the compressed fluid to flow from the first tank to the second tank but blocks the inverse flow. The low compressed fluid flowing from the compressed fluid source to the first tank is allowed to flow into the second tank via the communication pipe simultaneously.

Accordingly, the pressure within the second tank may be boosted in a short period of time. The check valve is capable of preventing the high compressed fluid within the second tank from flowing back into the first tank via the communication pipe.

According to an embodiment of the present invention, an intake switching valve is provided between the first tank and the main body of the compressor to switch between a state where the main body of the compressor sucks external air upon start-up of the main body, and a state where the main body sucks the compressed fluid from the first tank when the pressure within the second tank reaches the set pressure. The intake switching valve allows the main body of the compressor to suck the external air upon its start-up to reduce the resultant load.

According to an embodiment of the present invention, an assembly formed by combining the first tank, the main body of the compressor, and the second tank is provided with handgrips at both ends of the cylindrical bodies in the longitudinal direction. The compressor formed as the single assembly may be easily and safely carried to the place requiring the high compressed fluid by gripping the handgrips.

According to an embodiment of the present invention, the first tank, the main body of the compressor and the second tank are stored in the case, thus reducing the noise during the operation as well as improving the outer appearance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a booster type air compressor according to a first embodiment of the present invention;

FIG. 2 is a view showing a left side of the booster type air compressor shown in FIG. 1;

FIG. 3 is a circuit diagram of the booster type air compressor;

FIG. 4 is a timing chart representing the operation of the booster type air compressor;

FIG. 5 is a front view of a booster type air compressor according to a second embodiment of the present invention;

FIG. 6 is a front view of a booster type air compressor according to a third embodiment of the present invention;

FIG. 7 is a view showing a left side of the booster type air compressor shown in FIG. 6;

FIG. 8 is a front view of the booster type air compressor according to a fourth embodiment of the present invention with a partially broken view of the case;

FIG. 9 is a view showing a left side of the booster type air compressor shown in FIG. 8 with the partially broken view of the soundproof case; and

FIG. 10 is a circuit diagram of a booster type air compressor according to a modified example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A booster type air compressor will be described referring to the drawings as a compressor according to an embodiment of the present invention.

FIGS. 1 to 4 show a first embodiment of the present invention. Referring to FIGS. 1 and 2, a booster type air compressor 1 according to the first embodiment is formed by combining a first tank 2 to be described later, a main body 5 of the compressor, an electric motor 8, and a second tank 9 into a single assembly.

The first tank 2 forms a lower section of the air compressor 1 for storing compressed air at low pressure supplied from a compressed air source 33 to be described later as a cylindrical tank with both sides sealed. The first tank 2 has the cylindrical body in parallel with the second tank 9, and are horizontally installed with respect to a mount surface in the plant. Meanwhile, the first tank 2 is structured to have a sufficient capacity to absorb the pulsation of the low compressed air supplied from the compressed air supply source 33.

As the first tank 2 stores the low compressed air (for example, the pressure of about 0.5 MPa), it is structured to have the strength sufficient to resist the low pressure. That is, the first tank 2 may be formed using the inexpensive material which is easily processed, for example, a thin steel plate and parts.

As shown in FIG. 2, the first tank 2 is provided with an intake joint 3 and a low-pressure outlet joint 4. The intake joint 3 is connected to the compressed air supply source 33 via a filter 14 and a first reducing valve 15 which will be described later. The low-pressure outlet joint 4 may be connected to a pneumatic device (not shown) usable at the low pressure.

The main body 5 of the compressor sucks the low compressed air from the first tank 2 so as to be compressed. The main body 5 may be employed for various types of compressors such as rotary type and reciprocating type. In the embodiment, it is formed as a reciprocating compressor of V-type with two-cylinder single compression mechanism. The main body 5 includes crankcases 5A each formed on the respective tanks 2 and 9, and two compression units 5B of reciprocating type each mounted on the upper portion of the crankcase 5A. The main body 5 is linked with an electric motor 8 via a pulley and a belt (not shown).

Inlet portions of two compression portions 5B which form the main body 5 are connected to the first tank 2 via an intake pipe 6. Meanwhile, outlet portions of those two compression portions 5B are connected to an inflow joint 10 of the second tank 9.

The electric motors 8 are provided in the vicinity of the main body 5 on the respective tanks 2 and 9, and are rotated upon power supply to drive the main body 5.

The second tank 9 forms the lower section of the air compressor 1 together with the first tank 2. The second tank 9 stores the compressed air at high pressure supplied from the main body 5, which may have a cylindrical shape with both ends sealed likewise the first tank 2. The second tank 9 is arranged such that the longitudinal direction of the cylindrical body is in parallel with the first tank 2, and is installed horizontally with respect to the mount surface in the plant.

The second tank 9 stores the high compressed air (for example, approximately 1.0 MPa), and includes two inflow joints 10 and a single high-pressure outlet joint 11. The two inflow joints 10 are connected to the compression portions 5B of the main body 5 via outlet pipes 7, respectively. The high-pressure outlet joint 11 may be connected to a pneumatic device (not shown) to be used at the high pressure.

Configurations of the first and the second tanks 2 and 9 will be described hereinafter. In the first embodiment, the first tank 2 has substantially the same outer configuration as that of the second tank 9 in consideration with the productivity and the balance in the external appearance. Each of the first and the second tanks 2 and 9 may be formed to have the minimum possible volume for the purpose of making the air compressor 1 light-in-weight and compact.

A communication pipe 12 communicates the first tank 2 with the second tank 9, and distributes the low compressed air which has been supplied to the first tank 2 to the second tank 9. A check valve 13 to be described later is provided in an intermediate position of the communication pipe 12.

The check valve 13 is provided in the intermediate position of the communication pipe 12 for communicating the first tank 2 with the second tank 9. The check valve 13 allows the low compressed air to flow from the first tank 2 to the second tank 9 via the communication pipe 12 but blocks the inverse flow of the high compressed air from the second tank 9 to the first tank 2.

Various components installed in the air compressor 1 will be described referring to FIGS. 1 to 3.

The components of the first tank 2 will be described. The first filter 14 is provided between the compressed air source 33 and the first tank 2 in the plant for eliminating dust contained in the compressed fluid to be supplied from the compressed air source 33.

The first reducing valve 15 as the first inflow pressure control valve is provided downstream of the first filter 14 between the compressed air source 33 and the first tank 2. The first reducing valve 15 regulates the inflow of the compressed fluid at the pressure in excess of the specified pressure (for example, 0.5 MPa) into the first tank 2.

A low-pressure relief valve 16 provided in the tank 2 releases the compressed air to outside when the pressure within the first tank 2 exceeds the set pressure (for example, 0.5 MPa). A drain valve 17 is provided in the first tank 2 for discharging the drain within the first tank 2 to outside.

A second reducing valve 18 as a second inflow pressure control valve is provided between the first tank 2 and the main body 5, that is, at the intermediate position inside the intake pipe 6. The second reducing valve 18 prevents the compressed air at the pressure in excess of the specified pressure (for example, 0.5 MPa) from flowing to the main body 5 from the first tank 2.

A second filter 19 is provided downstream of the second reducing valve 18 at the intermediate portion inside the intake pipe 6. The second filter 19 eliminates dust, water content, and oil content of the compressed air supplied to the main body 5.

Components of the second tank 9 will be described referring to FIGS. 1 to 3.

A high-pressure relief valve 20 is provided on the second tank 9 for releasing the compressed air to outside when the pressure within the second tank 9 exceeds the set pressure (for example, 1.0 MPa). A drain valve 21 is provided in the second tank 9 for discharging the drain within the second tank 9 to outside.

A pressure switch 22 is provided on the second tank 9 for outputting a detection signal to a motor control switch 29 (described later) for controlling the electric motor 8. More specifically, the pressure switch 22 outputs a detection signal to stop the electric motor 8 when the pressure within the second tank 9 reaches 1.0 MPa, and further outputs the detection signal to start the electric motor 8 when the pressure within the second tank 9 decreases to 0.8 MPa.

A structure for reducing the load required to start the main body 5 will be described.

An intake switching valve 23 is provided in the intake pipe 6, which is switched to a state where the main body 5 sucks external air upon start-up thereof, and to a state where the main body 5 sucks the compressed air from the first tank 2 when the pressure within the second tank 9 reaches the set pressure (for example, 0.2 MPa).

The intake switching valve 23 is formed as a three-port two-position air pilot type switching valve for supplying external air to the main body 5 at a switching position (A) in a normal state. Meanwhile, upon supply of the pilot pressure, the valve is switched to a switching position (B) for supplying the compressed air from the first tank 2 to the main body 5. The pilot portion of the intake switching valve 23 is connected to the second tank 9 via a pilot pipe 24. An external inlet filter 25 is formed at a position where the external air is accommodated by the intake switching valve 23.

An electromagnetic switching valve 26 formed as the three-port two-position electromagnetic pilot type directional switching valve is provided close to the second tank 9 on the pilot pipe 24. When the power state is OFF, the valve is at a switching position (C) to allow the pilot portion of the intake switching valve 23 to be opened to the atmosphere via the pilot pipe 24. Meanwhile, the electromagnetic switching valve 26 is switched to a switching position (D) when the power state is ON for supplying the compressed air within the second tank 9 to the intake switching valve 23 via the pilot pipe 24.

A speed control valve 27 is provided close to the intake switching valve 23 of the pilot pipe 24 for reducing the flow rate of the pilot pipe 24 to delay the time (timing) for the air pressure from the second tank 9 to switch the intake switching valve 23.

Specifically, when the main body 5 is started, the intake switching valve 23 is not switched when the pressure within the second tank 9 is equal to or lower than 0.2 MPa. When the pressure within the second tank 9 reaches 0.2 MPa, the intake switching valve 23 may be switched. The main body 5 is allowed to accommodate the external air during a period until the intake switching valve 23 is switched, and also to operate the electric motor 8 at low load until the rated revolution number.

In a normal operation mode where the main body 5 is started and stopped in accordance with pressure change within the second tank 9, the pressure within the second tank 9 is not reduced to be equal to or lower than 0.2 MPa. Upon start-up of the main body 5, the intake switching valve 23 is momentarily switched in accordance with the pressure within the second tank 9 (for example, at approximately 0.8 MPa), thus failing to operate the main body 5 at the low load. The speed control valve 27 throttles the flow rate in the pilot pipe 24 to operate the main body 5 (electric motor 8) at the low load by delaying the switching timing of the intake switching valve 23 by a predetermined period even when the inner pressure with the second tank 9 is equal to or higher than 0.2 MPa.

An electric system for starting/stopping the motor 8 and the electromagnetic switching valve 26 will be described referring to FIG. 3.

A power switch 28 for the booster type air compressor 1 is used for starting/stopping the electric motor 8 (main body 5), and connected to a motor control switch 29 (described later).

The motor control switch 29 is provided between the electric motor 8 and a power supply 30, and connected to the power switch 28, the pressure switch 22 and a switching valve control switch 31 (described later). The motor control switch 29 is used for starting/stopping the electric motor 8 based on the detection signal from the pressure switch 22 or the starting/stopping signal from the power switch 28.

The switching value control switch 31 is connected to the pilot portion of the electromagnetic switching valve 26 which is switched thereby based on the signal from the motor control switch 29.

Four wheels 32 (only two wheels are shown) are provided below the first tank 2 and the second tank 9. Those wheels 32 allow the air compressor 1 as the entire body including the first tank 2 at the inlet side to be easily moved.

A compressed air source 33 supplies the compressed air into the plant, for example, the compressed air at the rated pressure of approximately 0.5 MPa via a plant piping 34.

The compression operation of the above-structured booster type air compressor 1 according to the first embodiment will be described referring to the timing chart showing in FIG. 4.

In the air compressor 1, the first tank 2 is connected to the compressed air source 33, and the pressure within the first tank 2 becomes 0.5 MPa as the supply pressure of the low compressed air. The pressure within the second tank 9 communicated with the first tank 2 via the communication pipe 12 becomes 0.5 MPa.

When the power switch 28 is turned ON in the aforementioned state, a start-up signal is input to the motor control switch 29 to drive and rotate the electric motor 8 for activating the main body 5. Simultaneously the start-up signal from the motor control switch 29 is input to the switching valve control switch 31 such that the electromagnetic switching valve 26 is switched to the switching position (D), and the compressed air within the second tank 9 is supplied to the pilot portion of the intake switching valve 23 via the pilot pipe 24. The flow rate of the compressed air which passes through the pilot pipe 24 is regulated by the speed control valve 27. So the intake switching valve 23 is switched from the switching position (A) to (B) with a predetermined delay time from start-up of the electric motor 8 and the main body 5, for example, in the range from 1 to 10 seconds.

The main body 5 is allowed to suck the external air upon start-up, thus reducing the starting load. As a result, the speed may immediately reach the rated revolution number of the electric motor 8. When the intake switching valve 23 is switched to the switching position (B) upon elapse of a predetermined time, the main body 5 sucks the preliminarily compressed low compressed air from the first tank 2, and further compresses (boosts) to allow efficient supply of the high compressed air into the second tank 9.

Meanwhile, when the pressure within the second tank 9 reaches 1.0 MPa, the high-pressure detection signal is output from the pressure switch 22 so as to be input to the motor control switch 9, thus stopping the electric motor 8. Simultaneously, the stop signal is input from the motor control switch 29 to the switching valve control switch 31 such that the electromagnetic switching valve 26 returns to the switching position (C). The pilot pipe 24, then, is opened to the atmosphere. This makes it possible to allow the intake switching valve 23 to return to the switching position (A) for sucking the external air.

When the pressure within the second tank 9 is lowered to 0.8 MPa, the low-pressure detection signal is output from the pressure switch 22 to be input to the motor control switch 29 for starting the electric motor 8. Simultaneously, the start-up signal from the motor control switch 29 is input to the switching valve control switch 31 to switch the electromagnetic switching valve 26 to the switching position p) for supplying the compressed air within the second tank 9 to the intake switching valve 23 via the pilot pipe 24. The main body 5 is operated as described above to allow supply of the high compressed air to the second tank 9.

When the power switch 28 is opened, the electric motor 8 is stopped, and the electromagnetic switching valve 26 is switched to the switch position (C) in response to the stop signal from the motor control switch 29 simultaneously. The pilot pipe 24 is then opened to the atmosphere to stop (end) the operation of the air compressor 1.

According to the first embodiment, the first tank 2, the main body 5, the electric motor 8, the second tank 9 and the like are combined into a single assembly. Accordingly, the booster type air compressor 1 may be easily carried as the single unit so as to be moved to the other place.

As a result, the booster type air compressor 1 may be installed in the small mount space with less labor and time. The work set for installing the inlet tank, the piping work and the like may be omitted to allow the booster type air compressor 1 to be installed in the place requiring the high compressed air with easy operation.

The first tank 2 connected to the plant piping 34 for supplying the compressed air prevents pulsation of the compressed air to be supplied, and separates the drain contained in the compressed air to be eliminated. The main body 5 compresses the preliminary compressed air to be further compressed again. As a result, the high compressed air may be supplied into the second tank 9 as well as to the pneumatic device connected to the second tank 9.

The low-pressure outlet joint 4 provided in the first tank 2 is capable of discharging the low compressed air which has been stored in the first tank 2. The high-pressure outlet joint 11 provided in the second tank 9 discharges the high compressed air stored therein. The single air compressor 1 is allowed to supply both the high compressed air and the low compressed air which may be adapted to various types of the pneumatic devices.

The first reducing valve 15 for regulating the inflow of the compressed air at the pressure in excess of the specified pressure (0.5 MPa) to the first tank 2 is capable of controlling the pressure within the first tank 2 to be within the specified pressure. This makes it possible to form the first tank 2 using the inexpensive material and the parts for lower pressure rather than the use of the material which resists the high pressure or the special parts.

The second reducing valve 18 for regulating the inflow of the compressed air at the pressure in excess of the specified pressure (0.5 MPa) from the first tank 2 the main body 5 is provided in the inlet pipe 6 for connecting the first tank 2 and the main body 5. This may prevent the compressed air at the pressure equal to or higher than the specified pressure from being supplied to the main body 5 while being kept from the damage and improving the reliability.

As the low-pressure relief valve 16 is provided in the first tank 2 for releasing the compressed air to outside when the inner pressure thereof exceeds the preliminary set pressure (0.5 MPa), the pressure within the first tank 2 may be maintained in the safe pressure range. Likewise, the high-pressure relief valve 20 for releasing the compressed air to outside when the inner pressure of the second tank 9 exceeds the set pressure (1.0 MPa), the pressure within the second tank 9 may be kept in the safe pressure range.

The path extending from the compressed air source 33 to the main body 5 is provided with the filters 14 and 19 for eliminating the dust contained in the compressed air. The dust contained in the compressed air, thus may be eliminated, and accordingly reduction in the life of the main body 5 owing to the intake dust may be prevented.

The first tank 2 and the second tank 9 have the cylindrical bodies in parallel with each other in the longitudinal direction, and are horizontally installed with respect to the mount surface of the plant. The air compressor 1 may have the height reduced resulting from the transverse arrangement of the tanks 2 and 9.

Drains within the first tank 2 and the second tank 9 may be easily discharged by opening the drain valve 17 for discharging the drain to outside provided in the first tank 2 and the drain valve 21 provided in the second tank 9.

As the first tank 2 and the second tank 9 are communicated via the communication pipe 12, the low compressed air which flows from the compressed air supply source 33 to the first tank 2 is allowed to flow into the second tank 9 in the communication pipe 12 simultaneously. The pressure within the second tank 9 may be boosted within the short period. The communication pipe 12 includes the check valve 13 which allows the flow of the compressed air from the first tank 2 to the second tank 9 but blocks the inverse flow. The check valve 13 is capable of preventing the high compressed air within the second tank 9 from returning to the first tank 2 via the communication piping 12.

The inlet pipe 6 includes the intake switching valve 23 which is operated to switch between a state where the main body 5 sucks the external air upon star-up, and a state where the main body 5 sucks the compressed air from the first tank 2 when the pressure within the second tank 9 reaches the set pressure. The intake switching valve 23 allows the main body 5 to suck the external air upon start-up to reduce the start-up load.

A second embodiment of the booster type air compressor according to the present invention will be described referring to FIG. 5.

In the embodiment, the first tank and the second tank have the cylindrical bodies in parallel with each other in the longitudinal direction, and vertically installed on the mount surface. In the second embodiment, the same components as those in the first embodiment will be designated with the same reference codes with dash.

FIG. 5 shows a booster type air compressor 41 according to the second embodiment. A first tank 42 and a second tank 43 which form the air compressor 41 have the cylindrical bodies in parallel with each other in the longitudinal direction, and vertically installed on the mount surface using leg portions 42A and 43A. This makes it possible to reduce the space requiring installation of the air compressor 41.

A main body 5′ of the compressor and an electric motor 8′ are mounted on a base 44 above the first tank 42 and the second tank 43. A power switch 28′ and a motor control switch 29′ are provided between the main body 5′ and the electric motor 8′.

The first tank 42 is provided with an inflow joint 3′, a low-pressure outlet joint 4′, a low-pressure relief valve 16′, and a drain valve 17′. Meanwhile, the second tank 43 is provided with a high-pressure outlet joint 11′ and a drain valve 21′. A check valve 13′ is provided on a communication pipe 12′ which communicates the first tank 42 and the second tank 43.

The inlet pipe 6′ includes a second reducing valve 18′, a second filter 19′, an intake switching valve 23′ and the like as well as an external inlet filter 25′, an electromagnetic switching valve 26′, a speed control valve 27′ and the like.

The above structured second embodiment provides substantially the same functions and effects as those derived from the first embodiment. Especially in the second embodiment, the first tank 42 and the second tank 43 have the cylindrical bodies in parallel with each other in the longitudinal direction, and vertically installed on the mount surface of the plant. The space requiring the installation may be reduced by the amount resulting from vertical arrangement of the first tank 42 and the second tank 43. This makes it possible to install the booster type air compressor 41 in the narrow space.

A booster type air compressor according to a third embodiment of the present invention will be described referring to FIGS. 6 and 7.

In the embodiment, the first tank and the second tank are arranged having a gap therebetween, and the main body of the compressor is installed between the first and the second tanks so as to be partially fit therebetween.

In the embodiment, the single assembly formed by combining the first tank, the main body and the second tank includes handgrips at both ends of the cylindrical body in the longitudinal direction such that the assembly is gripped. The third embodiment has substantially the same structure as that of the first embodiment. The main feature of the embodiment will only be described, and description and drawing of the other portion will be omitted.

FIG. 6 shows a booster type air compressor 51 according to a third embodiment. FIG. 7 shows a first tank 52 as a cylindrical body, and a second tank 53 arranged in parallel with and apart from the first tank 52. The first tank 52 and the second tank 53 are transversely arranged horizontally to the mount surface, and are connected with each other via a connector member 54. A predetermined gap 55 is formed between the first tank 52 and the second tank 53. The gap 55 partially accommodates a main body 62 to be described later and a lower section of the electric motor.

An inflow joint 56 and a low-pressure reducing valve 57 are provided on the first tank 52. A low-pressure outlet joint 58 is provided on the side of the low-pressure reducing valve 57. Meanwhile, a high-pressure outlet joint 60 is provided on the second tank 53 via the high-pressure reducing valve 59. The first tank 52 and the second tank 53 are connected via a communication pipe 61.

The main body 62 of the air compressor 51 and an electric motor 63 integrally assembled therewith in the axial direction are combined into a single compressor unit. The main body 62 formed as a reciprocating compressor mechanism of horizontal two-cylinder type is connected to the first tank 52 via an inlet pipe 64, and to the second tank 53 via an outlet pipe 65.

The compressor unit formed of the main body 62 and the electric motor 63 is provided between the first tank 52 and the second tank 53 as shown in FIG. 7, and the lower portion is partially accommodated in the gap 55 between the tanks 52 and 53.

Two handgrips 66 are attached to the single assembly formed by integrally combining the first tank 52, the second tank 53, and the main body 62. Those two handgrips 66 are positioned at both ends of the cylindrical bodies of the first tank 52 and the second tank 53, each protruding upward. The air compressor 51 may be moved by a user by gripping the handgrips 66.

The above structured third embodiment provides substantially the same functions and effects as those derived from the first embodiment. Especially in the third embodiment, the first tank 52 and the second tank 53 are arranged having the gap 55 therebetween for partially accommodating the main body 62 and the electric motor 63 therein. Accordingly, the booster type air compressor 51 may be integrally formed to become low, resulting in the compact structure.

The handgrips 66 are provided at both ends of cylindrical bodies of the first tank 52 and the second tank 53 in the longitudinal direction. The air compressor 51 may be easily and safely carried to the place requiring the high compressed air by gripping the handgrips 66.

FIGS. 8 and 9 show a booster type air compressor according to a fourth embodiment of the present invention.

The embodiment is structured to have the first tank, the main body of the compressor and the second tank stored in a case. As the fourth embodiment has substantially the same structure as that of the first embodiment, the main feature will only be described, and the other portion and the drawing will be omitted.

FIG. 8 shows a booster type air compressor according to the fourth embodiment. A first tank 72 is formed as a cylindrical body (see FIG. 9), and a second tank 73 is arranged in parallel with the first tank 72 at a predetermined interval. The first tank 72 and the second tank 73 are transversely placed so as to be horizontal to a base 86A of the case 86 as the mount surface (described later), which are connected via a connector member 74. A predetermined gap 75 is formed between the first tank 72 and the second tank 73 for accommodating a main body 82 of the compressor and a lower section of an electric motor 83.

The first tank 72 is provided with an inflow joint 76 which protrudes outward of the case 86, and a low-pressure outlet joint 78 which protrudes outside via a low-pressure reducing valve 77. Meanwhile, the second tank 73 is provided with a high-pressure outlet joint 80 protruding outside via a high-pressure reducing valve 79. The first tank 72 and the second tank 73 are connected via a communication pipe 81.

An electric motor 83 is integrally assembled with a main body of the air compressor 71. The main body 82 and the electric motor 83 are combined into the single compressor unit. The main body 82 is formed as a reciprocating compressor mechanism with one stage compression for horizontal opposing two-cylinder type, and is connected to the first tank 72 via an inlet pipe 84, and to the second tank 73 via an outlet pipe 85.

The compressor unit formed of the main body 82 and the electric motor 83 is provided between the first tank 72 and the second tank 73 as shown in FIG. 9, having the lower portion partially accommodated in the gap 75 formed between the tanks 72 and 73.

A box-like soundproof case 86 forms an outer shape of the air compressor 71, and has the base 86A having the lower side formed as the mount surface for accommodating the tanks 72, 73 thereon. The soundproof case 86 stores the first tank 72, the second tank 73, the main body 82, and the electric motor 83 to block the operation sound thereof so as not to be seen from outside.

The thus structured fourth embodiment provides substantially the same effects and functions as those derived from the third embodiment. In the fourth embodiment, especially the first tank 72, the second tank 73, the main body 82 and the electric motor 83 are stored in the soundproof case 86 so as to reduce the level of the operation sound, and to improve the outer appearance.

In the first embodiment, the first reducing valve 15 is provided as the first inflow pressure control valve between the compressed air source 33 and the first tank 2, and the second reducing valve 18 is provided as the second inflow pressure control valve between the first tank 2 and the main body 5. The present invention is not limited to the aforementioned structure but may be structured to have a first isolation valve 91 as the first inflow pressure control valve between the compressed air source 33 and the first tank 2, and a second isolation valve 92 as the second inflow pressure control valve between the first tank 2 and the main body 5. The aforementioned structure may be applied to the other embodiments.

In the first embodiment, the intake switching valve 23 for switching between a state where the main body 5 sucks air and a state where the main body 5 sucks the compressed air from the first tank 2 is formed as the switching valve of air pilot type using the compressed air within the second tank 9 as the pilot pressure. However, the present invention is not limited to the aforementioned structure. The intake switching valve may be formed as the electromagnetic valve which is switchable based on the electric signal from the pressure sensor and the like in the second tank 9.

In the first embodiment, the main body 5 is formed as the compressor of two cylinder reciprocating type. However, the main body may be formed as the compressor of the single cylinder reciprocating type, the scroll type compressor, the vane type compressor and the like. The aforementioned structure may be applied to the other embodiments.

In the respective embodiments, the booster type air compressor 1, 41, 51, or 71 is used as the compressor. However, the compressor for compressing the fluid other than nitrogen, or the compressor for compressing the fluid such as the cooling medium may be employed.

Claims

1. A compressor comprising:

a first tank connected to an external compressed fluid source for accommodating an inflow of a low compressed fluid from the external compressed fluid source;

a main body of the compressor for sucking the low compressed fluid from the first tank so as to be compressed; and

a second tank for storing a high compressed fluid compressed by the main body of the compressor, and for discharging the stored high compressed fluid to outside with a high-pressure outlet joint, wherein the first tank, the main body of the compressor, and the second tank are combined to form a single assembly.

2. The compressor according to claim 1, wherein the first tank is provided with a low-pressure outlet joint for discharging the low compressed fluid contained in the first tank.

3. The compressor according to claim 1, wherein a first inflow pressure control valve is provided between the compressed fluid source and the first tank for regulating the inflow of the compressed fluid at a pressure in excess of a specified pressure into the first tank.

4. The compressor according to claim 1, wherein a second inflow pressure control valve is provided between the first tank and the main body of the compressor for regulating the inflow of the compressed fluid at a pressure in excess of a specified pressure from the first tank to the main body of the compressor.

5. The compressor according to claim 1, wherein the first tank is provided with a relief valve which releases the compressed fluid to outside when a pressure within the first tank exceeds a set pressure.

6. The compressor according to claim 1, wherein a path extending from the external compressed fluid source to the main body of the compressor is provided with a filter for eliminating dust contained in the compressed fluid.

7. The compressor according to claim 1, wherein the first tank and the second tank have cylindrical bodies in parallel with each other in a longitudinal direction, and are horizontally installed with respect to a mount surface.

8. The compressor according to claim 7, wherein the first tank and the second tank are arranged with a gap therebetween, and the main body of the compressor is provided between the first tank and the second tank so as to be partially accommodated in the gap.

9. The compressor according to claim 7, wherein the single assembly formed by combining the first tank, the main body, and the second tank is provided with handgrips at both ends of the cylindrical bodies in a longitudinal direction for gripping the assembly.

10. The compressor according to claim 8, wherein the single assembly formed by combining the first tank, the main body, and the second tank is provided with handgrips at both ends of the cylindrical bodies in a longitudinal direction for gripping the assembly.

11. The compressor according to claim 1, wherein the first tank and the second tank have cylindrical bodies in parallel with each other in a longitudinal direction, and are vertically installed with respect to a mount surface.

12. The compressor according to claim 1, wherein each of the first tank and the second tank is provided with a drain valve for discharging a drain.

13. The compressor according to claim 1, further comprising:

a communication pipe for allowing the first tank and the second tank to communicate with each other,

wherein the communication pipe is provided with a check valve which allows the compressed fluid to flow from the first tank to the second tank but blocks an inverse flow.

14. The compressor according to claim 1, further comprising an intake switching valve provided between the first tank and the main body of the compressor, wherein the intake switching valve allows the main body to suck an external air upon its start-up and switches to a state where the main body sucks the compressed fluid from the first tank when a pressure within the second tank reaches a set pressure.

15. The compressor according to claim 1, wherein the first tank, the main body, and the second tank are stored in a case.