JP2009008093A - Air compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce noise due to operation of the motor of an air compressor. <P>SOLUTION: A pressure sensor 98, in addition to LEDs 88<SB>1</SB>-88<SB>8</SB>((1)-(8)), a motor 68, a power supply ON-switch 90, a power supply OFF-switch 92, and a silent mode switch 93, is connected to the control section 94 of the air compressor 10. The silent mode switch 93 is operated, for example, when performing operation at night or when using only one nailing machine. The control section 94 makes: control for performing ON/OFF control of the motor 68 according to a pressure value detected by the pressure sensor 98; and silent mode control for reducing motor noise in such a manner that when the silent mode switch 93 is switched ON for changing from a normal mode to a silent mode, the rotational speed of the motor 68 is reduced to a predetermined low rotational speed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an air compressor, and more particularly to an air compressor configured to drive or stop a drive unit according to the pressure of a tank that stores compressed air generated by an air compression unit.

  For example, in a construction site or the like, a nailing machine for driving nails into wood or the like with the pressure of compressed air is used. Thus, the nail driver used outdoors is configured to supply compressed air generated by a transportable air compressor and drive the nail loaded in the nail loading unit with air pressure.

  This type of air compressor includes a piston / cylinder part (air compression part) that sucks and compresses air, a motor (drive part) that drives the piston, a cover that covers the piston / cylinder part and the motor, and compressed air. And a storage tank.

  The control unit mounted on the air compressor monitors the pressure of the tank, drives the motor until the pressure in the tank reaches the upper limit value of the tank, and fills the tank with compressed air. When the pressure reaches the upper limit (motor stop pressure), the motor is temporarily stopped. When the pressure in the tank drops to the lower limit (motor restart pressure), the motor is started again and the tank is filled with compressed air. To do.

  In the air compressor, the state of not operating includes a case where the power is turned off and a case where the operation of the motor is stopped because the tank internal pressure reaches the upper limit value. The standby state in which the operation state of the air compressor is continued refers to a state in which the power is turned on, the tank internal pressure reaches the upper limit value, and the motor operation is stopped.

  On the other hand, in recent years, it is desired to use a plurality of nailing machines connected in parallel and used at the same time, or to use a pneumatically driven tool used at a higher pressure (for example, 1 MPa or more). Therefore, the tank internal pressure is maintained at a high pressure (for example, 1 MPa to 3 MPa) so that the pressure does not become insufficient, and the air supply amount can be increased.

As an example of such an air compressor configured to generate high-pressure compressed air with a large amount of air supply, for example, a first air compression mechanism and a second air compression composed of a pair of piston / cylinder mechanisms There is a so-called horizontally opposed type two-stage air compressor in which a mechanism is opposed (see, for example, Patent Document 1).
JP 2000-283052 A (page 3, FIG. 3)

  However, in the air compressor in which the pressure in the tank is increased and the air supply amount is increased as described above, for example, when one worker uses a nailing machine at night, etc. There are cases where an air supply amount that is used by a worker is not required. Further, depending on the work contents, a high pressure may not be required.

  However, the conventional air compressor is controlled so as to keep the inside of the tank at a predetermined high pressure even in the above-described case, and can also cope with a large amount of air supply. The motor rotation speed (number of rotations) is set high.

  For this reason, when the pressure in the tank becomes high, the load on the motor increases and the sound generated from the motor or the like increases, and even when the motor is rotated at a high speed, high-frequency sound generated from the motor is not generated. There is a problem that it becomes large, especially noise at night.

  An object of the present invention is to provide an air compressor that is controlled so as to suppress noise generation when high pressure is not required or when a large amount of air supply is not required.

  In order to solve the above problems, the present invention has the following means.

  In order to solve the above problems, the present invention has the following features.

  According to the first aspect of the present invention, an air compressor that sucks and compresses air, a drive unit that drives the air compressor, a tank that stores compressed air generated by the air compressor, and a pressure in the tank An air compressor comprising: a pressure detection means for detecting; and a control means for controlling a drive unit so as to keep the pressure in the tank detected by the pressure detection means within a preset target pressure range. The means includes a target pressure range changing means capable of changing the target pressure range to a normal target pressure range and a low pressure range where at least the upper limit value is lower than the upper limit value of the normal target pressure range by an external switch operation. Therefore, by changing the target pressure to the low pressure range, it is possible to switch the operation state so that the motor can be operated at a low speed at a speed at which the motor noise is reduced.

  According to a second aspect of the present invention, the control means can change the rotation speed of the drive unit to a normal rotation speed and a low-speed rotation speed lower than the normal rotation speed by an external switch operation. By changing the rotational speed of the drive unit to a low speed, the operating state can be switched so that the motor can be driven at a low speed with a reduced rotational speed.

  According to a third aspect of the present invention, in the second aspect, the normal mode in which the target pressure range is set to the normal target pressure range and the rotation speed of the drive unit is set to the normal rotation speed by the external switch operation, and the target pressure The range can be switched to the low pressure range and the silent mode in which the rotational speed of the drive unit is low. The target pressure is changed to the low pressure range, and the rotational speed of the drive unit is changed to the low speed. By doing so, it becomes possible to switch an operation state so that it may drive at low speed with the rotation speed in which a motor sound falls.

  According to a fourth aspect of the present invention, there is provided an air compressor comprising: an air compression unit that sucks and compresses air; a drive unit that drives the air compression unit; and a control unit that controls the drive unit. The control means includes rotation speed changing means capable of changing the rotation speed of the drive unit to a normal rotation speed and a low speed rotation speed lower than the normal rotation speed by an external switch operation. By changing the rotation speed to a low rotation speed, it is possible to switch the operation state so that the low-speed operation is performed at a rotation speed at which the motor noise is reduced.

  The invention according to claim 5 is characterized in that, in any one of claims 2 to 4, the rotation speed changing means switches the rotation speed by controlling the current, so that the rotation speed of the drive unit is reduced. By changing to the rotation speed, it becomes possible to switch the operation state so that the motor can be operated at a low speed at a rotation speed at which the motor noise is reduced.

  As described above, in the first aspect of the present invention, the target pressure range is set by an external switch operation, the normal target pressure range, and the low pressure range where at least the upper limit value is lower than the upper limit value of the normal target pressure range. Since the target pressure range changing means that can be changed to the above is provided, when the target pressure range is set to the low pressure range, the load on the motor can be reduced, and noise generated from the motor or the like can be reduced.

  According to a second aspect of the present invention, in the first aspect of the present invention, the rotational speed of the drive unit can be changed between a normal rotational speed and a lower rotational speed that is lower than the normal rotational speed by an external switch operation. By providing the changing means, it is possible to switch the operation state so that the low-speed operation is performed at the rotation speed at which the motor noise is reduced.

  Furthermore, in the invention of claim 3, in claim 2, a normal mode in which the target pressure range is set to the normal target pressure range and the rotation speed of the drive unit is set to the normal rotation speed by an external switch operation; The target pressure range can be switched to the low pressure range and the silent mode where the drive speed is low, and the target pressure is changed to the low pressure range, and the drive speed is set to low speed. By changing to, the load on the motor can be reduced, and noise generated from the motor or the like can be reduced. It is possible to switch the operation state so that the motor can be operated at a low speed at a rotational speed at which the motor noise is reduced.

  Furthermore, in the invention of claim 4, there is provided a rotational speed changing means capable of changing the rotational speed of the drive unit to a normal rotational speed and a low rotational speed lower than the normal rotational speed by an external switch operation. As a result, the high frequency noise of the motor can be reduced when the rotation speed is low.

  Further, in the fifth aspect of the present invention, in the second, third, and fourth aspects, the rotational speed changing means switches the rotational speed by controlling the current. Can be reduced.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a perspective view showing an embodiment of an air compressor according to the present invention. FIG. 2 is a perspective view showing a state where the cover 22 is removed. FIG. 3 is a side view of the air compressor. FIG. 4 is a plan view of the air compressor. FIG. 5 is a front view of the air compressor. FIG. 6 is a rear view of the air compressor.

  As shown in FIGS. 1 to 6, an air compressor 10 is a small compressor configured to supply compressed air to a pneumatic nailing machine (not shown), for example, outdoors such as a construction site. It is.

  The air compressor 10 has a pair of tanks 14 and 16 formed in a cylindrical shape on a frame 12 and is supported in parallel. An air compression unit 18 that generates compressed air is formed above the tanks 14 and 16. A drive unit 20 that drives the air compression unit 18 is mounted. Further, a resin cover 22 integrally formed so as to cover the air compression unit 18 and the drive unit 20 is attached to the upper portions of the tanks 14 and 16.

  Further, leg portions 24 to 27 are provided at lower portions of both ends of the tanks 14 and 16. Further, grip portions 28 and 30 formed in a U-shape are fixed to both ends of the frame 12. The air compressor 10 is transported while gripping the grip portions 28 and 30.

  In the air compressor 10, air discharge units 32 and 34 are provided on both sides of the air compression unit 18. The air discharge units 32 and 34 are pressure control valves 36 and 38 connected to the extraction pipes (not shown) of the tanks 14 and 16 and pressures indicating the discharge pressure values adjusted by the pressure control valves 36 and 38. 40 and 42, and discharge ports 44 to 47 for discharging compressed air having a pressure adjusted by the pressure adjusting valves 36 and 38.

  The pressure adjusting valves 36 and 38 adjust the discharge pressure by turning the handles 36a and 38a. Further, the discharge ports 44 to 47 are provided with quick couplers to which hoses (not shown) connected to the nailing machine are connected.

  The pressure adjusting valve 36 can be adjusted to any value between 0 and 0.8 MPa, and a low pressure tool generally used at about 0.7 MPa is connected to the discharge ports 44 and 45. . Here, the upper limit value 0.8 MPa corresponds to the second pressure of the present invention, and the discharge ports 44 and 45 correspond to the low pressure discharge port.

  Moreover, the pressure regulating valve 38 can be adjusted to an arbitrary value between 0 and 2.5 MPa, and a high pressure tool generally used at 1 to 2.5 MPa is connected. Here, the upper limit value of 2.5 MPa corresponds to the first pressure of the present invention, and the discharge ports 46 and 47 correspond to the high-pressure discharge port.

  Further, an operation panel 48 is provided on the cover 22. The operation panel 48 is provided with a power switch and various display lamps, but is provided in the recess 23 of the cover 22 so that the power is not turned off even if an object is placed.

  As shown in FIG. 2, the cover 22 is detachably attached, and is removed from the frame 12 during maintenance of the air compression unit 18 and the drive unit 20. As described above, when the cover 22 is removed, the pressure adjusting valves 36 and 38, the pressure gauges 40 and 42, and the discharge ports 44 to 40 are provided in addition to the air compression unit 18 and the drive unit 20 provided on the upper portions of the tanks 14 and 16. 47 is exposed.

  Here, the structure of the compression part 18 and the drive part 20 is demonstrated.

  FIG. 7 is a cross-sectional view showing the internal configuration of the compression unit 18 and the drive unit 20. As shown in FIG. 7, the compression unit 18 includes piston / cylinder mechanisms 62 and 64 disposed on both sides of the casing 60. The piston / cylinder mechanisms 62 and 64 are formed in directions different by 180 °.

  The piston / cylinder mechanisms 62 and 64 include pistons 62a and 64a, cylinders 62b and 64b, connecting rods 62c and 64c, and cylinder heads 62d and 64d. In FIG. 7, the piston 64a is hidden and cannot be seen.

  The casing 60 includes a first chamber 60 a that houses the rotating portion of the compression unit 18, a second chamber 60 b that houses a filter 66 provided in the introduction path of the compression air, and a motor 68 of the drive unit 20. And a third room 60c for storing the.

  The compression unit 18 compresses air to a high pressure (for example, high pressure value = 2 to 3 MPa) by a two-stage compression method, and the air introduced from the air inlet 22 m by the first-stage piston / cylinder mechanism 62. Is compressed further by the second-stage piston / cylinder mechanism 64 and stored in the tanks 14 and 16. Since the tanks 14 and 16 are in communication with each other, they are held at the same pressure.

  The first-stage piston / cylinder mechanism 62 and the second-stage piston / cylinder mechanism 64 are connected via a communication pipe (not shown).

  One connecting rod 62 c has one end formed integrally with the piston 62 a and the other end supported by the rotating shaft 74 via a bearing 70. One end of the other connecting rod 64 c is formed integrally with a piston (not shown), and the other end is supported by the rotating shaft 74 via a bearing 72. The rotary shaft 74 is rotatably supported by a bearing 76 held by the partition wall 60 d of the casing 60 and a bearing 78 held by the motor cover 79.

  A first fan (impeller) 80 for sucking outside air from the first air inlet 22m is fixed to one end 74a of the rotating shaft 74. A second fan (impeller) 82 for sucking motor cooling air from the air inlet 22n is fixed to the other end 74b of the rotating shaft 74.

  The air sucked from the air inlet port 22m by the first fan 80 is cooled by being blown onto the surfaces of the casing 60 and the piston / cylinder mechanisms 62 and 64, and part of the air is filtered through the filter 66. After being compressed by the first stage cylinder 62b later, it is supplied to the second stage cylinder 64b and further compressed.

  The second fan 82 is provided at the entrance 79 a of the motor cover 79, sucks air for cooling the motor 68 and blows it around the motor 68. The motor 68 includes a magnet (rotor) 68a fixed to the rotating shaft 74, a stator 68b disposed on the outer periphery of the magnet 68a, and a coil 68c wound around the stator 68b. The motor 68 is reduced in size and weight, and reciprocates the pistons 62a and 64a via the rotating shaft 74 and rotationally drives the fans 80 and 82.

  Further, since the drive unit 20 houses the fan 82 and the motor 68 inside the cylindrical motor cover 78, the rotation of the fan 82 sucks external air from the air introduction port 22 n, and the inside of the motor cover 79. Through the plurality of exhaust holes 22s. Inside the motor cover 79, as indicated by an arrow in FIG. 8, the flow velocity of the air flow generated by the rotation of the fan 82 increases, and this air flow efficiently takes away the heat generated by the motor 68, thereby cooling the motor 68.

  Here, the configuration of the operation panel 48 will be described.

FIG. 8 is a plan view showing the configuration of the operation panel 48. In addition, the circled numbers shown in FIG. As shown in FIG. 8, the operation panel 48 includes a power ON switch 90, a power OFF switch 92, a silent mode switch 93, and pressure display red LEDs 88 _{1 to} 88 that display pressure changes in the tanks 14 and 16. ₆ ((1) to (6)), an operation mode display LED 88 ₇ ((7)) for displaying the operation mode, and an operation state display LED 88 ₈ ((8)) for displaying the operation state. ing. The operation state display LEDs 88 ₈ ((8)) are displayed separately in two colors (green and orange) so that the difference between the two types of operation modes (normal mode and silent mode) can be understood.

  The power ON switch 90 and the power OFF switch 92 are membrane switches (momentary switches) that are switched from OFF to ON when pressed, and remain OFF when not pressed.

The LEDs 88 _{1 to} 88 ₈ ((1) to (8)) are formed of light emitting diodes soldered on a substrate (not shown) disposed below the operation panel 48, and the operation panel 48 has a rectangular shape. Shaped lens is exposed. The red LEDs 88 _{1 to} 88 ₆ ((1) to (6)) are turned on or off step by step according to the pressure change in the tanks 14 and 16, and the pressure values in the tanks 14 and 16 are changed depending on the number of lights. indicate.

FIG. 9 is a block diagram showing a configuration of each electric system provided in the air compressor 10. In addition, the circled numbers shown in FIG. As shown in FIG. 9, the control unit 94 of the air compressor 10 includes LEDs 88 _{1 to} 88 ₈ ((1) to (8)), a motor 68, a power ON switch 90, a power OFF switch 92, and a silent mode. In addition to the switch 93, a pressure sensor 98 is connected. The controller 94 controls the on / off of the motor 68 according to the pressure value detected by the pressure sensor 98 as described later, and turns on / off each of the LEDs 88 _{1 to} 88 ₈ ((1) to (8)). Control display by blinking.

  The silent mode switch 93 is a switch that is operated, for example, when working at night or when using only one nail driver. The pressure sensor 98 is a pressure detection means for detecting the pressure in the tanks 14 and 16 and is configured to output a signal (voltage) corresponding to a change in pressure.

  As will be described later, when the silent mode switch 93 is turned on to switch from the normal mode to the silent mode, the control unit 94 decelerates the rotational speed of the motor 68 to a lower rotational speed than the preset normal mode, The rotation speed is changed, and the target pressure range of the tank pressure is changed from the upper limit value 3 MPa and the lower limit value 2.5 MPa in the normal mode (normal target pressure range) to the upper limit value 1.5 MPa and the lower limit value in the silent mode (low pressure range). Is changed to 0.8 MPa, and silent mode control is performed to reduce the operating noise of the compressor. Therefore, the control unit 94 constitutes a target pressure range changing unit that changes the target pressure range to an arbitrary range, and also constitutes a rotation speed changing unit that reduces the rotation speed of the motor 68 that is the drive unit. The change in the tank internal pressure in the normal mode is indicated by a solid line in FIG. 10A, and the change in the tank internal pressure in the silent mode is indicated by a broken line in FIG.

FIGS. 10A to 10H are timing charts showing examples of control operations of the tank internal pressure change and pressure display red LEDs 88 _{1 to} 88 ₆ ((1) to (6)) and the motor 68. The upper limit value of the pressure charged in the tanks 14 and 16 is a pressure at which the motor 68 stops, and the lower limit value is a tank pressure at which the motor 68 is restarted. In addition, the circled numbers shown in FIG.

  As shown in FIG. 10A, the pressure in the tanks 14 and 16 gradually increases as the operation of the air compressor 10 starts (time T1), and the pressure in the tanks 14 and 16 is set to a preset upper limit value. When the pressure reaches 3.0 MPa (time T7), as shown in FIG. 10 (H), the motor 68 is turned off (standby state), and the compressed air in the tanks 14 and 16 is nail driver (not shown). Etc.) and tank pressure drops.

  Then, as shown in FIG. 10A, when the pressure in the tanks 14 and 16 decreases to a preset lower limit value 2.5 MPa (time T8), as shown in FIG. The operation of 68 is resumed, and the compressed air is supplied to the tanks 14 and 16. Thereby, the pressure in the tanks 14 and 16 gradually increases with the supply of compressed air.

  Thereafter, when the pressure in the tanks 14 and 16 rises to the upper limit value of 3.0 MPa (time T9), the motor 68 stops again and enters a standby state. Thus, the air compressor 10 is alternately performed in the compression operation state and the standby state in the normal operation mode.

As shown in FIG. 10B, the red LED for pressure display 88 ₁ ((1)) lights up when the pressure value detected by the pressure sensor 98 reaches the first stage pressure of 0.5 MPa (time T2). Then, it is displayed that the pressure value in the tanks 14 and 16 has reached 0.5 MPa.

As shown in FIG. 10C, the red LED 88 ₂ for pressure display ((2)) lights up when the pressure value detected by the pressure sensor 98 reaches the second stage pressure 1.0 MPa (time T3). Then, it is displayed that the pressure value in the tanks 14 and 16 has reached 1.0 MPa.

As shown in FIG. 10D, the red LED for pressure display 88 ₃ ((3)) lights up when the pressure value detected by the pressure sensor 98 reaches the third stage pressure 1.5 MPa (time T4). Then, it is displayed that the pressure value in the tanks 14 and 16 has reached 1.5 MPa.

As shown in FIG. 10E, the red LED 88 ₄ for pressure display ((4)) lights up when the pressure value detected by the pressure sensor 98 reaches the fourth stage pressure of 2.0 MPa (time T5). Then, it is displayed that the pressure value in the tanks 14 and 16 has reached 2.0 MPa.

As shown in FIG. 10 (F), the pressure display red LED 88 ₅ ((5)) lights up when the pressure value detected by the pressure sensor 98 reaches the fifth stage pressure 2.5 MPa (time T6). Then, it is displayed that the pressure value in the tanks 14 and 16 has reached 2.5 MPa.

As shown in FIG. 10G, the red LED for pressure display 88 ₆ ((6)) lights up when the pressure value detected by the pressure sensor 98 reaches the sixth stage pressure of 3.0 MPa (time T7). Then, it is displayed that the pressure value in the tanks 14 and 16 has reached 3.0 MPa. The red LED for pressure display 88 ₆ ((6)) is turned off when the pressure value detected by the pressure sensor 98 is reduced to 2.5 MPa or less (time T8), and the pressure value in the tanks 14 and 16 is changed to the first value. The fact that the five-stage pressure has been reduced to 2.5 MPa is displayed.

Further, the red LED 88 ₆ for pressure display ((6)) is interlocked with the on / off of the motor 68, and the pressure in the tanks 14 and 16 reaches the sixth stage pressure of 3.0 MPa (time T9). When the operation of 68 is stopped, it lights up. The red LED 88 ₆ for pressure display ((6)) is turned off when the pressure in the tanks 14 and 16 is reduced to the fifth stage pressure of 2.5 MPa or less and the operation of the motor 68 is resumed.

In this way, the pressure display red LED 88 ₆ ((6)) is turned off or lit in conjunction with the on / off of the motor 68, so that the operator can visually confirm the on / off of the motor 68 and malfunction. The motor 68 is not stopped at a glance. Further, even if the tank pressure fluctuates near the upper limit value of 3.0 MPa due to a temperature change or the like, the pressure display red LED 88 ₆ ((6)) is lit until the operation of the motor 68 is resumed. The display of the pressure display red LED 88 ₆ ((6)) becomes stable, and it is possible to give the worker a sense of security.

  FIGS. 11A to 11C are graphs showing an example of the characteristics of the motor 68. As shown in FIG. 11A, in the normal mode I, the motor 68 of this embodiment has a performance of rotating at 2400 rpm when a voltage of 100 V is applied in a no-load state, for example. ing. Since the load gradually increases as the pressure in the tanks 14 and 16 increases, when the pressure in the tanks 14 and 16 reaches 3 MPa while being controlled under a condition where the input voltage is constant, the rotational speed of the motor 68 is increased. Has dropped to 2000 rpm.

  In the silent mode II, the current and voltage are controlled so that the motor rotation speed is 1500 rpm. In addition, in the silent mode II, the upper limit value that is the target value of the tank pressure is set to 1.5 MPa, so that the motor 68 is rotated at a lower speed than in the normal mode, as shown in FIG. The motor 68 is rotated and stopped when the tank pressure reaches 1.5 MPa.

  As shown in FIG. 11 (B), the motor 68 rotates at 2000 rpm when the pressure of the tanks 14 and 16 is 3 MPa and the applied voltage is 100V. In addition, when the pressure of the tanks 14 and 16 is 3 MPa and the applied voltage is reduced to 65 V due to a decrease in the power supply voltage, the rotation speed of the motor 68 is reduced to 1000 rpm due to the load. However, the relationship between the rotational speed and the voltage is merely an example, and it goes without saying that it varies depending on conditions such as motor output and tank pressure.

  In the silent mode, the relationship is as shown in FIG. 11C, and when the applied voltage is reduced to 50V, the rotational speed is reduced to 1000 rpm.

  From this, for example, in the normal mode, if the voltage applied to the motor 68 is 80 to 100 V, the motor 68 can drive the piston / cylinder mechanisms 62 and 64 at a rotational speed of 1500 rpm or more. In addition, when the voltage applied to the motor 68 is reduced to 65 V or less, the air compressor 10 reduces the rotational speed to 1500 rpm or less, and the load on the piston / cylinder mechanisms 62 and 64 is relatively increased, resulting in compressed air. As a result, the number of rotations of the fans 80 and 84 for cooling the motor 68 and the piston / cylinder mechanisms 62 and 64 is decelerated and the cooling efficiency is greatly reduced. In that case, temperature rise of the motor 68 and the piston / cylinder mechanisms 62 and 64 becomes a problem.

  Similarly, in the silent mode, when the speed is reduced to 1200 rpm or less (55 V), not only the amount of compressed air generated but also the rotational speed of the motor 68 decreases.

  Here, a motor control process executed by the control unit 94 will be described.

  FIG. 12 is a flowchart showing motor control processing executed by the control unit 94. In FIG. 12, after the plug of the power cord (not shown) of the air compressor 10 is inserted into an AC 100V outlet in step S <b> 11 (hereinafter, “step” is omitted), the control unit 94 sets the power ON switch 90. If it is turned on, the process proceeds to S12, and it is checked whether or not energization to the motor 68 is on. In S12, when the energization to the motor 68 is not in the ON state, the process proceeds to S13, and it is checked whether or not the power OFF switch 92 has been pressed. If the power OFF switch 92 is pressed in S13, the current process is terminated. If the power OFF switch 92 is not pressed in S13, the process returns to S12.

  When the energization of the motor 68 is on in S12, the process proceeds to S14, where the motor 68 is driven to start the compression operation by the piston / cylinder mechanisms 62, 64.

  In the next S15, it is checked whether or not the rotation speed N of the motor 68 detected by the motor rotation detection sensor 102 has been reduced to a predetermined value Na (for example, Na = 1900 rpm) or less. In S15, when the rotation speed N of the motor 68 is not less than or equal to a predetermined value Na set in advance, the process proceeds to S16 and a warning process described later is turned off. Subsequently, in S17, the counter value n is reset to n = 0.

In S18, the red LEDs 88 _{1 to} 88 ₆ ((1) to (6)) are turned on or off stepwise in accordance with the pressure change in the tanks 14 and 16, and the tanks 14 and 16 are turned on or off depending on the number of LED lighting. Displays the pressure value. Then, it returns to S12 and performs the process after S12.

In S15, when the rotational speed N of the motor 68 is equal to or less than a predetermined value Na set in advance, for example, a plurality of electric tools connected to the extension cord are used at the same time and the voltage is 65V (in the silent mode). Is determined to have fallen to 50 V or less, and the process proceeds to S19 to turn off the energization of the motor 68 and stop the motor 68. Subsequently, the process proceeds to S20 to warn that a voltage drop has occurred. As a warning method of the present embodiment, for example, the six red LEDs 88 _{1 to} 88 ₆ ((1) to (6)) are flashed all at once to notify that the motor 68 is stopped due to a voltage drop.

  In the next S21, the counter value n is incremented to n = 1. In S22, it is checked whether the counter value n is n = 4. In S22, when n <4, the process proceeds to S23 and waits until a predetermined time T (for example, T = 5 seconds) set in advance.

  In S23, when the predetermined time T elapses, the process proceeds to S24, and energization of the motor 68 is switched on. As a result, the compression operation by the piston / cylinder mechanisms 62 and 64 is resumed. Thereafter, the process returns to S14, and the processes after S14 are repeated. At this time, when the rotation speed N of the motor 68 detected by the motor rotation detection sensor 102 is equal to or greater than the predetermined value Na, normal operation is possible, and thus the processing of S16, S17, and S18 described above is executed.

  In S15, when the rotation speed N of the motor 68 is equal to or less than a predetermined value Na (for example, Na = 1000 rpm), for example, a plurality of electric tools connected to the extension cord are used at the same time. It is determined that the voltage has decreased to 50 V or less, and the processes of S19 to S22 are executed again. When the processes of S19 to S22 are repeated three times, the counter value n becomes n = 4 in S22, so that the process proceeds to S25 and it is checked whether or not the power ON switch 90 is turned on.

In S25, when the power ON switch 90 is turned on, the process proceeds to S26, and the voltage drop warning is turned off. That is, the six red LEDs 88 _{1 to} 88 ₆ ((1) to (6)) are turned off all at once. In step S27, the counter value n is reset to n = 0. Then, after switching to a pressure displaying red _{LED88 1 ~88 6 ((1)} ~ (6)) in S18, returns to S12, again executes S12 and subsequent steps.

  If the power ON switch 90 is not turned on in S25, the process proceeds to S28 to check whether or not the power OFF switch 92 is turned on. If the power OFF switch 92 is not turned on in S28, the process returns to S25.

In S28, when the power OFF switch 92 is turned on, the process proceeds to S29, and the voltage drop warning is turned off. That is, the six red LEDs 88 _{1 to} 88 ₆ ((1) to (6)) are turned off all at once and switched to the pressure display in the tanks 14 and 16. In step S30, the counter value n is reset to n = 0. Thereafter, the current process is terminated.

  As described above, when the rotation speed N of the motor 68 is equal to or less than the predetermined value Na set in advance, it is determined that the voltage has decreased to 50 V or less, the motor 68 is stopped, and waiting for a predetermined time to elapse. By switching on the energization of the motor 68, the burden on the motor 68 is reduced and the life of the motor 68 is extended, and the operation of the motor 68 is automatically restarted and the operator operates the power ON switch 90. Since it is not necessary to do this, the burden on the operator can be reduced.

  Further, in the silent mode, as shown in FIG. 11C, the voltage-rotational speed characteristic changes, so the set value Na changes.

  As described above, when the silent mode switch 93 is turned on, the control unit 94 changes the target pressure range to an arbitrary pressure range so that the operation state is changed to a low speed operation at a rotational speed at which the motor sound is reduced. It becomes possible to switch. Therefore, for example, when working at night or when only one nailing machine is used, the motor 68 can be controlled so that the rotational speed N of the motor 68 operates at a low rotational speed N2 or less. It is possible to reduce noise associated with driving.

  The noise during normal operation was measured and found to be 65 dB. However, it was confirmed that the noise was reduced to 60 dB when the motor 68 was driven in the silent mode as described above.

  Moreover, in the silent mode, the motor load is reduced by setting the upper limit value of the target pressure in the tank to the low-noise mode value P2, so that noise can be reduced.

  Here, the control process of the normal mode and the silent mode executed by the control unit 94 will be described.

FIG. 13 is a flowchart showing control processing for the normal mode and the silent mode executed by the control unit 94. As shown in FIG. 13, the control unit 94 confirms whether or not the silent mode is set in S41. In S41, when the silent mode switch 93 is turned on and the silent mode is set, the process proceeds to S42 to switch to the silent mode, and the operation mode display LED 88 ₇ ((7)) is switched from green to orange. Display that the mode is silent.

  In next S43, the rotation speed N of the motor 68 is controlled to a preset low speed rotation speed N2 (for example, 1500 rpm), and the target pressure Pa in the tank is set to the silent mode value P2 (for example, the upper limit value is set to 1.5 MPa). The lower limit value is set to 0.8 MPa (target pressure changing means).

In S41, when the silent mode switch 93 is turned off and the normal mode is set, the process proceeds to S44 to switch to the normal mode, and the operation mode display LED 88 ₇ ((7)) is turned from orange to green. Switch to lighting and display the normal mode.

  Subsequently, in S45, the rotation speed N of the motor 68 is controlled to a preset rotation speed N1 (for example, 2000 rpm), and the target pressure Pa in the tank is set to the normal mode value P1 (for example, the upper limit value is set to 3.0 MPa). The lower limit is set to 2.5 MPa (target pressure changing means).

  In next S46, it is checked whether or not the pressure P in the tank is equal to or lower than the lower limit value of the set mode (normal mode or silent mode). In S46, when the pressure P in the tank is equal to or lower than the lower limit value of the setting mode, the process proceeds to S47, and energization of the motor 68 is continued and the motor 68 is driven to rotate at the rotation speed corresponding to the setting mode.

  In S46, if the pressure P in the tank is not less than or equal to the lower limit value of the setting mode, the process proceeds to S48, and whether or not the pressure P in the tank is equal to or higher than the upper limit value of the set mode (normal mode or silent mode). To check. In S48, when the pressure P in the tank is equal to or higher than the upper limit value of the setting mode, the process proceeds to S49, and energization of the motor 68 is stopped.

  In S48, when the pressure P in the tank is not equal to or higher than the upper limit value of the setting mode, the current process is terminated and the process returns to S41.

  As described above, when the silent mode switch 93 is turned on, the control unit 94 switches the operation state so that the low-speed operation is performed at the rotation speed at which the motor sound is reduced by changing the target pressure to an arbitrary pressure value. It becomes possible. Therefore, for example, when working at night or when using only one nailing machine, the motor 68 can be controlled to operate at a low speed N2 so that the motor 68 can be rotated. The accompanying noise can be reduced.

  Further, when high pressure is not required and only the low pressure discharge port side is used depending on the work contents, low pressure discharge can be sufficiently used even in the silent mode, and noise of the motor or the like can be reduced.

  The noise during normal operation was measured and found to be 65 dB, but it was confirmed that the noise was reduced to 60 dB when the motor 68 was driven in the noise mode as described above.

  Further, in the silent mode, setting the target pressure Pa in the tank to the silent mode value P2 (shortens the load operation time of the motor 68 and increases the unload operation time, which also reduces noise. can do.

  In the above-described embodiment, the configuration in which the piston / cylinder mechanisms 62 and 64 are compressed in two stages is given as an example. However, the configuration is not limited to this, and one or more piston / cylinder mechanisms may be provided. .

  Moreover, in the said Example, although the structure which has a pair of tanks 14 and 16 was mentioned as an example, it is not restricted to this, The thing of the structure which provided one or three or more tanks may be used.

  In the above-described embodiment, the motor speed and the target pressure range are changed in the silent mode. However, only the motor speed or only the target pressure range may be changed. Furthermore, the user can selectively change the silent mode in which both the motor rotation speed and the target pressure range are reduced, the low-volume supply silent mode in which only the motor rotation speed is reduced, and the low pressure use silent mode in which only the target pressure range is reduced. You may do it.

  In the above embodiment, the target pressure range of the tank pressure is changed from the upper limit value 3 MPa in the normal mode (normal target pressure range) and the lower limit value 2.5 MPa to the upper limit value 1.5 MPa in the silent mode (low pressure range), and the lower limit value is set to 0. However, the present invention is not limited to this, and only the upper limit value may be lowered to 2.7 MPa, for example.

  In the above embodiment, the example in which the rotation speed changing unit sets the rotation speed to a low value and adjusts the current and voltage so as to be the rotation speed is shown. However, in the present invention, the rotation speed is changed. Therefore, if the motor is an AC motor, the frequency value of one is changed. If the motor is a DC motor, the voltage is changed to a lower value. Also good.

  In the above embodiment, the reciprocating compressor is shown. However, the compressor is not limited to this and may be a scroll or screw type compressor.

  In the above embodiment, an example in which the target pressure range and the rotation speed can be changed in two stages has been described. However, the target pressure range and the rotation speed may be changed in multiple stages and further in a linear manner.

It is a perspective view which shows one Example of the air compressor by this invention. It is a perspective view which shows the state which removed the cover 22 of the air compressor. It is a side view of an air compressor. It is a top view of an air compressor. It is a front view of an air compressor. It is a rear view of an air compressor. 2 is a cross-sectional view showing the internal configuration of a compression unit 18 and a drive unit 20. FIG. 3 is a plan view showing a configuration of an operation panel 48. FIG. 2 is a block diagram showing a configuration of each electric system provided in the air compressor 10. FIG. It is a timing chart showing an example of the control operation for red internal pressure changes and pressure display tank _{LED88 1 ~88 6 ((1)} ~ (6)) and the motor 68. 3 is a graph showing an example of characteristics of a motor 68. It is a flowchart which shows the motor control process which the control part 94 performs. It is a flowchart which shows the control process of the normal mode and silent mode which the control part 94 performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Air compressor 12 Frame 14, 16 Tank 18 Air compression part 20 Drive part 22 Cover 24-27 Leg part 28, 30 Grip part 32, 34 Air discharge part 36, 38 Pressure regulation valve 40, 42 Pressure gauge 44-47 Exhaust outlet 48 operation panel 60 casing 62, 64 the piston-cylinder mechanism 66 filter 68 motor 79 motor cover 80 first fan 82 second fan ₈₈ 1-88 ₆ pressure display for red LED
8 ₈ LED for operation mode display
88 ₈ LED for operation status display
90 Power ON switch 92 Power OFF switch 93 Silent mode switch 94 Control unit 98 Pressure sensor

Claims (5)

An air compression section that sucks and compresses air;
A drive unit for driving the air compression unit;
A tank for storing compressed air generated by the air compression unit;
Pressure detecting means for detecting the pressure in the tank;
Control means for controlling the drive unit so that the pressure in the tank detected by the pressure detection means is kept within a preset target pressure range;
In an air compressor comprising:
The control means can change the target pressure range by changing the target pressure range from a normal target pressure range and a low pressure range in which at least the upper limit value is lower than the upper limit value of the normal target pressure range by an external switch operation. An air compressor comprising means.   The control means includes a rotation speed changing means capable of changing the rotation speed of the drive unit into a normal rotation speed and a low-speed rotation speed lower than the normal rotation speed by an external switch operation. The air compressor according to claim 1. The control means, by a switch operation from the outside, a normal mode in which the target pressure range is the normal target pressure range and the rotation speed of the drive unit is the normal rotation speed;
The air compressor according to claim 2, wherein the target pressure range can be switched to a low-pressure pressure range and a silent mode in which the rotational speed of the drive unit is the low-speed rotational speed. An air compression section that sucks and compresses air;
A drive unit for driving the air compression unit;
Control means for controlling the drive unit;
In an air compressor comprising:
The control means includes a rotation speed changing means capable of changing the rotation speed of the drive unit to a normal rotation speed and a low-speed rotation speed lower than the normal rotation speed by an external switch operation. And air compressor.   The air compressor according to any one of claims 2 to 4, wherein the rotation speed changing means switches the rotation speed by controlling an electric current.

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