Air compressor

Abstract

To solve such a problem that an air compressor, in particular an intake filter thereof requires cleaning work for removing dust, and the cleaning work is performed normally by blowing compressed air in a tank, and it is therefore desirable that an appropriate amount of compressed air is jetted at a proper timing.SOLUTION: A appropriate amount of clean air is jetted to a part of the air compressor at a proper timing by automatically opening / closing a valve device 40 in linkage with the drop of tank pressure during draining drain water from the tank. When the tank pressure drops to an outflow opening pressure, an outflow valve 47 is moved by the energizing force of an outflow side energizing member 51 and then an outflow port 46 is opened. Thus, the compressed air in the tank 2 is jetted from a clean air piping 60. The valve device 40 is automatically opened / closed with a change of the tank pressure, and consequently cleaning work for blowing out dust can be done even in circumstances where there is no electric power supply.SELECTED DRAWING: Figure 8

Description

[Technical Field]

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

[0002] An air compressor has a compressed air generating unit that generates compressed air by compressing outside air drawn into a cylinder with a piston. The generated compressed air is temporarily stored in a tank. The compressed air in the tank is then supplied to the air tool. A filter is installed at the outside air intake of the compressed air generating unit to prevent foreign matter from entering. The filter is regularly maintained to prevent clogging.

[0003] Patent Document 1 discloses a technology in which a solenoid valve is opened in conjunction with a user's operation to stop operation, causing compressed air in a tank to be blown from the other end of a pipe onto a filter and its surroundings, thereby blowing away dust. Patent Document 2 discloses a technology in which compressed air in a tank is sprayed into the crankcase via a reverse injection pipe, thereby removing dust and other particles adhering to the filter. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7005765 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-127506 Summary of the Invention [Problem to be solved by the invention]

[0005] In the technology disclosed in Patent Document 1, the filter is cleaned only when the device is stopped (standby state) with power supplied, and the filter is cleaned every time the device is accidentally stopped, making it difficult to clean the filter efficiently at the appropriate time. In the technology disclosed in Patent Document 2, if a relatively thick wool felt or the like is used for the filter to suppress sound leakage from the crankcase, it is necessary to increase the air pressure and injection flow rate of the compressed air injected into the crankcase. This makes efficient cleaning difficult.

[0006] In the present disclosure, the appropriate amount of compressed air is injected in conjunction with changes in tank pressure, thereby enabling efficient cleaning of the air compressor. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, an air compressor includes a tank that stores generated compressed air and a drain discharge device that discharges drain water from the tank. The air compressor includes a valve device that opens the drain discharge device and uses air pressure to open when the air pressure in the tank drops to an outlet opening pressure, thereby allowing the compressed air in the tank to flow out. The air compressor includes a clean air pipe that is connected to the outlet of the valve device and directs the compressed air in the tank to a part of the air compressor.

[0008] Therefore, when the drain discharge device is opened to discharge the water from the tank at the end of work, the valve device opens when the air pressure inside the tank drops to the outlet opening pressure, and the appropriate amount of compressed air (clean air) inside the tank is sprayed from the clean air piping. The sprayed clean air blows away dust and other particles, efficiently cleaning the air compressor. The valve device is opened using the air pressure inside the tank. Therefore, unlike when using a solenoid valve, for example, the valve device opens in conjunction with the discharge of drain water and sprays clean air even in an environment without power supply. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 2 is an overall perspective view of the air compressor. [Figure 2] This is a left side view of the air compressor with the main cover and cooling fan removed. [Figure 3] 3 is a cross-sectional view taken along the line III-III in FIG. 2, showing a cross-sectional view of the compression mechanism. [Figure 4] This is a vertical cross-sectional view of the valve device. This figure shows the initial state when the tank pressure is zero. In the initial state, the inlet is closed and the outlet is open. [Figure 5] 1 is a longitudinal cross-sectional view of the valve device, showing the state in which the outflow valve has moved to a position that closes the outflow port when the tank pressure rises. [Figure 6] 1 is a longitudinal cross-sectional view of the valve device, showing the state in which the inlet valve has moved to a position that opens the inlet port when the tank pressure rises. [Figure 7] 1 is a longitudinal cross-sectional view of the valve device, showing the state in which the inlet is open and the outlet is closed when the tank pressure is at normal operating pressure. [Figure 8] 1 is a longitudinal cross-sectional view of the valve device, showing the state in which the outflow valve has moved to a position that opens the outflow port when the tank pressure drops. [Figure 9] 1 is a longitudinal cross-sectional view of the valve device, showing the inlet valve moved to a position where it closes the inlet port. [Figure 10] 4 is a diagram showing the open / closed state of the valve device in relation to the air pressure in the tank. FIG. [Figure 11] FIG. 1 is a front view of an air compressor equipped with a manually operated clean air valve instead of a valve device. DETAILED DESCRIPTION OF THE INVENTION

[0010] According to one embodiment, the valve device closes using air pressure when the air pressure in the tank increases, so that the valve device is always kept closed by air pressure when the air pressure in the tank increases.

[0011] According to one embodiment, the valve device has an inlet valve that opens and closes an inlet connected to the tank, and an outlet valve that opens and closes an outlet. When the air pressure in the tank increases, at least one of the inlet valve and the outlet valve is closed, and when the air pressure in the tank decreases, both the inlet valve and the outlet valve are opened. Thus, for example, the air pressure in the tank moves the inlet valve to close the inlet. The air pressure in the tank moves the outlet valve to open the outlet. When both the inlet and the outlet are open, the valve device is opened and clean air is sprayed.

[0012] According to one embodiment, when the air pressure in the tank increases and reaches an outlet closing pressure, the outlet valve closes, and when the air pressure reaches an inlet opening pressure higher than the outlet closing pressure, the inlet valve opens. Therefore, as the air pressure in the tank increases, the outlet valve and the inlet valve are never both open, so the valve device remains closed and clean air is not injected.

[0013] According to one embodiment, when the air pressure in the tank drops to an outlet opening pressure, the outlet valve opens, and when the air pressure drops to an inlet closing pressure lower than the outlet opening pressure, the inlet valve closes. Therefore, as the air pressure in the tank drops, both the outlet valve and the inlet valve are open, and the valve device is in an open state. When the valve device is opened, clean air is sprayed.

[0014] According to one embodiment, the compressor mechanism generates compressed air, and the outlet opening pressure is lower than the restart pressure at which the compression mechanism is restarted. Therefore, when the air pressure in the tank drops to an air pressure lower than the restart pressure, the valve device opens and clean air is injected.

[0015] According to one embodiment, the valve device has an inlet valve that opens and closes an inlet connected to the tank, and is attached to the tank with the inlet valve facing downward, thereby preventing water from entering the valve device.

[0016] According to one embodiment, the inlet valve and the outlet valve are arranged coaxially and overlap each other, thereby enabling the inlet valve and the outlet valve to be arranged compactly, thereby making the valve device compact.

[0017] According to one embodiment, the valve device has an inlet-side case having an inlet and movably holding an inlet valve, and an outlet-side case having an outlet and movably holding an outlet valve. The inlet valve is biased in a closing direction by an inlet-side biasing member. The outlet valve is biased in an opening direction by an outlet-side biasing member.

[0018] Therefore, the inlet valve moves to close the inlet due to the biasing force of the inlet-side biasing member, and moves to open the inlet due to an increase in air pressure inside the tank. The outlet valve moves to open the outlet due to the biasing force of the outlet-side biasing member, and moves to close the outlet due to an increase in air pressure inside the tank. The inlet valve is biased to the closing side and moves to the opening side due to air pressure, and the outlet valve is biased to the opening side and moves to the closing side due to air pressure. This allows the opening and closing operation of the valve device to be linked to fluctuations in air pressure inside the tank, even in an environment without power supply. [Example]

[0019] As shown in Figures 1 to 3, the air compressor 1 has two cylindrical tanks 2 that are long from front to back. The generated compressed air is stored in the two tanks 2. A total of four legs 3 are provided in front and behind the two tanks 2. Each leg 3 is made of a rubber material with high vibration resistance. Side protectors 3a are attached to each leg 3. A drain discharge device 10 for discharging drain water is provided between the front parts of the two tanks 2. The tops of the two tanks 2 are connected to each other by a base 4. A compression mechanism 20 is mounted on the top surface of the base 4. Handles 5 for carrying are attached to the front and rear of the base 4, spanning the tops of the two tanks 2. Figure 1 shows the compression mechanism 20 covered by a main body cover 6.

[0020] Two high-pressure outlets 8 and two low-pressure outlets 7 are arranged on the left and right sides of the front of the main body cover 6. Compressed air of, for example, 2.5 MPa is supplied from the high-pressure outlet 8. Compressed air of, for example, 0.85 MPa is supplied from the low-pressure outlet 7. Adjustment dials 7a and 8a are provided above the outlets 7 and 8, respectively, for setting the discharge pressure. An operating panel 9, mainly used for startup operations and including various display units, is provided on the front upper surface of the main body cover 6.

[0021] As shown in Figures 2 and 3, the compression mechanism 20 is exposed when the main body cover 6 is removed. The compression mechanism 20 has a cylindrical crankcase 21. The crankcase 21 is fixed onto the base 4. A first cylinder 22 is connected to the front of the crankcase 21. A second cylinder 23 is connected to the rear of the crankcase 21. The interior of the crankcase 21 is open to the outside air.

[0022] A first piston 24 is housed in the first cylinder 22 so as to be able to reciprocate back and forth. The first piston 24 is connected to a motor shaft 31 of an electric motor 30 via a first rod 26. A second piston 25 is housed in the second cylinder 23 so as to be able to reciprocate back and forth. The second piston 25 is connected to the motor shaft 31 of the electric motor 30 via a second rod 27.

[0023] An electric motor 30 is supported on the right side of the crankcase 21. The electric motor 30 is a brushless motor that can generate a relatively large starting torque. The electric motor 30 has an annular rotor 32 and a similarly annular stator 33 that is located on the inner periphery of the rotor 32. The stator 33 is fixed to the right side of the crankcase 21. A motor shaft 31 is connected to the center of the rotor 32. A cooling fan 34 is connected to the right end of the motor shaft 31. As the cooling fan 34 rotates, heat generated by the electric motor 30 is dissipated, thereby cooling the electric motor 30.

[0024] The motor shaft 31 extends leftward through the center of the stator 33. The motor shaft 31 is rotatably supported between the right and left sides of the crankcase 21 via a right bearing 35 and a left bearing 36. An intake section 28 is provided on the left side of the crankcase 21. Outside air is introduced into the crankcase 21 through the intake section 28.

[0025] The left end of motor shaft 31 protrudes from the center of intake section 28. A cooling fan 37 is attached to the left end of motor shaft 31. As cooling fan 37 rotates, outside air is blown onto intake section 28.

[0026] One rotation of the motor shaft 31 causes the first piston 24 and the second piston 25 to reciprocate alternately back and forth. The compressed air generated by the forward movement of the first piston 24 is compressed again by the backward movement of the second piston 25, generating high-pressure compressed air. The high-pressure compressed air (e.g., approximately 4.5 MPa) generated in two stages is stored in the tank 2 via piping 29.

[0027] Compressed air of, for example, a maximum of approximately 4.5 MPa (maximum pressure P4) is stored in the two tanks 2. When the air pressure of the compressed air in the tanks 2 (hereinafter simply referred to as air pressure or tank pressure) reaches the maximum pressure P4, the electric motor 30 is stopped. This puts the compression mechanism 20 into a standby state and temporarily stops the generation of compressed air.

[0028] The compressed air in the tank 2 is supplied to external pneumatic equipment and the like via the discharge ports 7, 8, thereby reducing the tank pressure. When the tank pressure drops to, for example, approximately 2.3 MPa (restart pressure P3), the electric motor 30 starts and the compression mechanism 20 is restarted. This replenishes the compressed air in the tank 2. In this way, the tank pressure is constantly detected so that the tank pressure is maintained within the range of approximately 2.3 to 4.5 MPa, and the start and stop operations of the compression mechanism 20 are controlled based on this. As a result, compressed air at a stable pressure (normal operating pressure) within the range of approximately 2.3 to 4.5 MPa is supplied to external pneumatic equipment and the like.

[0029] When the operation of the air compressor 1 is stopped, a drain discharge operation is performed as part of the maintenance work to drain the drain water in the tank 2. As shown in Figure 2, a drain discharge device 10 for draining the water in the tank 2 is provided in front of the air compressor 1. A drain valve 11 is provided midway through the drain discharge device 10. The drain valve 11 is opened and closed by manually operating a drain cock 11a. An upstream pipe 10a of the drain discharge device 10 is connected to the tank 2. The end of a downstream pipe 10b of the drain discharge device 10 is drawn between the two tanks 2.

[0030] A sound-absorbing member 12 is placed between the two tanks 2. Stainless steel wool is used for the sound-absorbing member 12, for example. The sound-absorbing member 12 is tightly packed and held in a cylindrical container 13 that is open downward. The end (drain discharge port) of the downstream pipe 10b of the drain discharge device 10 is inserted into the sound-absorbing member 12. This reduces the noise of drain water being discharged.

[0031] The water in the tank 2 is mixed with the compressed air and drained by the drain discharge device 10. Therefore, the compressed air in the tank 2 is released into the atmosphere as the drain discharge device 10 drains the water. This causes the tank pressure to gradually decrease. The air compressor 1 is designed to use an appropriate amount of compressed air as clean air to blow away dust and other particles during the process of releasing the compressed air in the tank 2 by the drain discharge device 10.

[0032] The air compressor 1 has a valve device 40 that opens by using air pressure when the drain discharge device 10 is opened and the air pressure in the tank 2 drops to an outflow opening pressure P5, allowing the compressed air in the tank 2 to flow out. The valve device 40 is attached in an upright position to the top of the left-side tank 2.

[0033] FIG. 4 shows the details of the valve device 40. The valve device 40 has an inlet case 41, an outlet case 42, and a connecting case 43. The inlet case 41 has an inlet 44. The inlet 44 is connected to the tank 2 via a coupling pipe 2a. An inlet valve 45 is held in the inlet case 41 so that it can move up and down. The valve device 40 is attached to the tank 2 in an upright position, so that the inlet 44 and the inlet valve 45 face downward. This prevents water from the tank 2 from entering the valve device 40 through the inlet 44. The outlet case 42 has an outlet 46. An outlet valve 47 is held in the outlet case 42 so that it can move up and down. The inlet case 41 and the outlet case 42 are integrally connected to each other by the cylindrical connecting case 43. The connecting case 43 has a passage hole 48. The passage hole 48 constantly connects the inner periphery of the connecting case 43 to the atmosphere.

[0034] The inlet valve 45 is biased in a direction to close the inlet 44 (downward in the figure) by an inlet-side biasing member 50. The outlet valve 47 is biased in a direction to open the outlet 46 (downward in the figure) by an outlet-side biasing member 51. A seal member 52 provides an airtight seal between the inlet 44 and the inlet valve 45. A seal member 53 provides an airtight seal between the outlet 46 and the outlet valve 47.

[0035] The inlet valve 45 and the outlet valve 47 are arranged coaxially and are capable of relative movement along the same axis. The inlet valve 45 is provided with a housing recess 45a, a support recess 45b, and an air passage 45c, all of which are coaxially arranged. The outlet case 42 is provided with a cylindrical support portion 42a that protrudes downward from the center of the lower surface. The cylindrical support portion 42a extends into the housing recess 45a.

[0036] The outflow valve 47 is disposed on the center line of the cylindrical support portion 42a, on the center line of the accommodation recess 45a, and on the center line of the support recess 45b. The support shaft 47a of the outflow valve 47 is inserted into the support recess 45b of the inflow valve 45. The space between the support shaft 47a and the support recess 45b is constantly airtight sealed by a seal member 54. The bottom side of the support recess 45b is constantly in communication with the inflow port 44 via an air passage 45c. Therefore, tank pressure constantly acts on the underside 47c of the outflow valve 47 via the air passage 45c.

[0037] The gap between the inner circumferential side of the inlet case 41 and the outer circumferential side of the inlet valve 45 is always airtight sealed by a seal member 55. The inner circumferential side of the inlet case 41 and the accommodating recess 45a of the inlet valve 45 are always in communication with each other by an air passage 45d. The gap between the cylindrical support portion 42a of the outlet case 42 and the accommodating recess 45a of the inlet valve 45 is always airtight sealed by a seal member 56. A clean air pipe 60 is connected to the outlet port 46. The tip side of the clean air pipe 60 is connected to, for example, the intake section 28 of the compression mechanism 20. The clean air blown out through the valve device 40 is sprayed toward the intake section 28 through the clean air pipe 60. This blows away dust and the like from the intake section 28.

[0038] 4, in the initial state where the air pressure (tank pressure) inside the tank 2 is zero, the inlet valve 45 is held at the lowest position by the inlet-side biasing member 50. As a result, the inlet valve 45 enters the inner circumferential side of the seal member 52, and the inlet port 44 is closed to the tank 2.

[0039] In the initial state, the outflow valve 47 is held in its lowest position by the outflow-side biasing member 51. This disengages the seal member 53 from the outflow port 46, leaving the outflow port 46 open. The lowest position of the outflow valve 47 is where the flange portion 47b abuts against the bottom of the accommodation recess 45a. As shown in Figure 10, as the tank pressure increases or decreases from the initial state, the inflow valve 45 and outflow valve 47 move, automatically opening and closing the valve device 40. In Figure 10, the open states of the inflow valve 45 and outflow valve 47 are indicated by circles, and the closed states are indicated by crosses.

[0040] When the drain discharge device 10 is closed and the compression mechanism 20 is activated, compressed air is generated and the air pressure in the tank 2 increases. When the tank pressure increases from the initial state in which the inlet 44 is closed and the outlet 46 is open to air pressure P1 (e.g., 0.5 MPa), the outlet 46 is closed. As shown in FIG. 5, the tank pressure P1 acting on the lower surface 47c of the outlet valve 47 via the air passage 45c causes the outlet valve 47 to move upward against the biasing force of the outlet-side biasing member 51. This presses the seal member 53 against the outlet 46, closing the outlet 46. The tank pressure P1 corresponds to the air pressure (outlet closing pressure) at which the outlet 46 is closed.

[0041] When the tank pressure rises to opening pressure P2 (e.g., 2 MPa) while both the inlet 44 and the outlet 46 are closed, the inlet 44 opens. As shown in FIGS. 6 and 7 , the tank pressure (opening pressure P2) acting on the lower surface 45e of the inlet valve 45 causes the inlet valve 45 to move upward against the biasing force of the inlet-side biasing member 50. This causes the inlet valve 45 to be disengaged from the inner circumferential side of the seal member 52, thereby opening the inlet 44. When the inlet valve 45 is disengaged from the inner circumferential side of the seal member 52, the lower surface 45f of the large diameter portion, in addition to the lower surface 45e, becomes a pressure-receiving surface on which the tank pressure (opening pressure P2) acts, and the pressure-receiving area of ​​the inlet valve 45 suddenly increases. As a result, the inlet valve 45 moves upward quickly, and the inlet 44 is instantly fully opened.

[0042] With the inlet 44 open and the outlet 46 closed, the tank pressure rises to a maximum air pressure P4 (e.g., 4.5 MPa). At the point when the tank pressure reaches P4, the electric motor 30 stops and the compression mechanism 20 enters a standby state. When the tank pressure drops to, for example, a restart pressure P3 (e.g., 2.3 MPa) due to the compressed air in the tank 2 being supplied to an external device, the electric motor 30 starts and the compression mechanism 20 is restarted. This replenishes compressed air into the tank 2. When the tank pressure is replenished to the maximum pressure P4, the compression mechanism 20 enters a standby state again. Compressed air is output to external devices within the tank pressure range P3 to P4 (e.g., 2.3 to 4.5 MPa). The tank pressures P3 to P4 correspond to normal operating pressures. When the tank pressure fluctuates within the normal operating pressure range P3 to P4, the outlet 46 of the valve device 40 is not opened.

[0043] After work is completed, the power is shut off and the drain discharge device 10 is opened to drain the water from the tank 2. Compressed air is released through the drain discharge device 10 along with the water in the tank 2, causing the tank pressure to drop. As shown in Figures 8 and 10, when the tank pressure drops to an outlet opening pressure P5 (e.g., 1.3 MPa), the outlet 46 opens. The outlet opening pressure P5 corresponds to the air pressure (outlet opening pressure) at which the outlet 46 opens.

[0044] When the tank pressure drops to the outflow opening pressure P5, the tank pressure acting on the underside 47c of the outflow valve 47 via the air passage 45c weakens, causing the outflow valve 47 to move downward due to the biasing force of the outflow-side biasing member 51. This disengages the seal member 53 from the outflow port 46, opening the outflow port 46.

[0045] When both the inlet 44 and the outlet 46 are open, the compressed air in the tank 2 flows into the clean air piping 60 via the outlet 46. The compressed air (clean air) that flows into the clean air piping 60 is injected into, for example, the intake part 28 of the compression mechanism 20. This cleans the intake part 28 and its surroundings.

[0046] 9 and 10, when the tank pressure drops to inlet closing pressure P6 (e.g., 0.2 MPa), the air pressure pushing up the inlet valve 45 drops. As a result, the inlet valve 45 moves downward due to the biasing force of the inlet-side biasing member 50, and the inlet valve 45 enters the inner peripheral side of the seal member 52. This closes the inlet port 44. The compressed air in the tank 2 is released through the drain discharge device 10 and flows out through the valve device 40, so that all of the compressed air in the tank 2 is released to the outside, and the tank pressure becomes zero. This causes the valve device 40 to return to its initial state, with the inlet port 44 closed and the outlet port 46 open, as shown in FIG.

[0047] According to the embodiment described above, the air compressor 1 has the valve device 40 that, when the drain discharge device 10 is opened and the air pressure in the tank 2 drops to the outflow opening pressure P5, uses the air pressure to open the outlet 46 and discharge the compressed air from the tank 2. The outlet 46 of the valve device 40 is connected to a clean air pipe 60 whose tip side faces the intake section 28 of the compression mechanism 20.

[0048] Therefore, when the drain discharge device 10 is opened to discharge the water in the tank 2 at the end of work, the valve device 40 opens when the air pressure in the tank 2 drops to the outflow opening pressure P5, and an appropriate amount of compressed air (clean air) in the tank 2 is sprayed from the clean air piping 60. The sprayed clean air blows away, for example, dust and the like in the intake section 28 and its surroundings, efficiently cleaning the air compressor 1. The valve device 40 is opened by utilizing the air pressure in the tank 2. Therefore, unlike when a solenoid valve is used, for example, the valve device 40 automatically opens in conjunction with the discharge of drain water and sprays clean air even in an environment without power supply.

[0049] According to the embodiment, when the air pressure in the tank 2 increases, the air pressure is used to close the outlet 46 and close the valve device 40. Therefore, when the air pressure in the tank 2 increases, the valve device 40 is always kept closed by the air pressure.

[0050] According to the embodiment, the valve device 40 has an inlet valve 45 that opens and closes an inlet 44 connected to the tank 2, and an outlet valve 47 that opens and closes an outlet 46. When the air pressure in the tank 2 increases, at least one of the inlet valve 45 and the outlet valve 47 is closed, and when the air pressure in the tank 2 decreases, both the inlet valve 45 and the outlet valve 47 are opened. Therefore, for example, the inlet valve 45 moves due to the air pressure in the tank 2, closing the inlet 44. The air pressure in the tank 2 moves the outlet valve 47, opening the outlet 46. When both the inlet 44 and the outlet 46 are opened, the valve device 40 is opened and clean air is sprayed.

[0051] According to the embodiment, when the air pressure in the tank 2 increases and the tank pressure reaches the outflow closing pressure P1, the outflow port 46 closes, and when the tank pressure exceeds the inflow opening pressure P2, which is higher than the outflow closing pressure P1, the inflow port 44 opens. Therefore, during the process of increasing the tank pressure, the outflow port 46 and the inflow port 44 are never both open, so the valve device 40 is maintained in a closed state and clean air is not injected.

[0052] According to the embodiment, when the tank pressure drops and reaches the outflow opening pressure P5, the outflow port 46 opens, and when the tank pressure drops below the inflow closing pressure P6, which is lower than the outflow opening pressure P5, the inflow port 44 closes. Therefore, during the process of the tank pressure dropping, both the outflow port 46 and the inflow port 44 are open, and the valve device 40 is in an open state. When the valve device 40 is opened, clean air is sprayed.

[0053] According to this embodiment, the outflow opening pressure P5 is lower than the restart pressure P3 at which the compression mechanism 20 is restarted. Therefore, when the tank pressure drops to an air pressure lower than the restart pressure P3, the valve device 40 is opened and clean air is injected.

[0054] According to the embodiment, the valve device 40 has an inlet valve 45 that opens and closes an inlet 44 connected to the tank 2, and is attached to the tank 2 with the inlet valve 45 facing downward. Therefore, water is prevented from entering the valve device 40.

[0055] According to the embodiment, the inlet valve 45 and the outlet valve 47 are arranged coaxially and overlapping each other, and are arranged so as to be relatively movable on the same axis. Therefore, the inlet valve 45 and the outlet valve 47 are arranged compactly. This allows the valve device 40 to be made compact.

[0056] According to the embodiment, the valve device 40 has an inlet-side case 41 having an inlet 44 and movably holding an inlet valve 45, and an outlet-side case 42 having an outlet 46 and movably holding an outlet valve 47. The inlet-side case 41 and the outlet-side case 42 are connected by a connecting case 43. The inlet valve 45 is biased in a closing direction by an inlet-side biasing member 50. The outlet valve 47 is biased in an opening direction by an outlet-side biasing member 51.

[0057] Therefore, the inlet valve 45 moves due to the biasing force of the inlet-side biasing member 50 to close the inlet 44, and moves due to an increase in tank pressure to open the inlet 44. The outlet valve 47 moves due to the biasing force of the outlet-side biasing member 51 to open the outlet, and moves due to an increase in tank pressure to close the outlet 46. The inlet valve 45 is biased to the closing side and moves to the opening side due to air pressure, and the outlet valve 47 is biased to the opening side and moves to the closing side due to air pressure. As a result, the opening and closing operation of the valve device 40 is linked to fluctuations in the air pressure in the tank 2, even in an environment without power supply.

[0058] Various modifications can be made to the embodiment described above. For example, although the configuration in which compressed air (clean air) is injected from the clean air pipe 60 toward the intake section 28 of the compression mechanism 20 has been exemplified, the clean air may be injected toward other parts such as the electric motor 30 or the tank 2.

[0059] The tip end of the clean air pipe 60 may be branched to allow clean air to be sprayed simultaneously to a plurality of locations.

[0060] The tank pressures P1, P2, P5, and P6 at which the inlet 44 and outlet 46 are opened and closed can be changed appropriately by changing the area of ​​the pressure-receiving surfaces of the inlet valve 45 and outlet valve 47, or by changing the biasing force of the inlet side biasing member 50 and outlet side biasing member 51.

[0061] The illustrated valve device 40 can be similarly applied to an air compressor having a compression mechanism with one piston, and also to an air compressor having one tank.

[0062] A drain discharge device 70 shown in Fig. 11 can be used in place of the illustrated valve device 40. The drain discharge device 70 is manually operated and has a drain valve 71 and a clean air valve 72. The drain valve 71 and the clean air valve 72 are integrally connected to each other. The drain valve 71 and the clean air valve 72 are opened and closed simultaneously by rotating a common lever 73.

[0063] An upstream pipe 71a of the drain valve 71 is connected to the tank 2. A downstream pipe 71b of the drain valve 71 is inserted into the sound-deadening member 12 arranged between the two tanks 2, just like the drain discharge device 10. This reduces the noise of drain water being discharged.

[0064] An upstream pipe 72a of the clean air valve 72 is also connected to the tank 2. A downstream pipe 72b of the clean air valve 72 is directed toward the intake section 28 of the compression mechanism 20. The downstream pipe 72b corresponds to the clean air pipe 60 illustrated above.

[0065] According to the drain discharge device 70, when drain water is to be discharged, the lever 73 is rotated to open both the drain valve 71 and the clean air valve 72. When the drain valve 71 is opened, the water in the tank 2 is drained from the downstream pipe 71b and compressed air is released.

[0066] When the clean air valve 72 is opened, clean air is sprayed from the downstream piping 72b onto the intake section 28 and its surroundings, thereby blowing away dust and other particles from the intake section 28 and its surroundings, cleaning the air compressor 1. The drain discharge device 70 can discharge drain water and spray clean air even in an environment without power. [Explanation of symbols]

[0067] 1...Air compressor 2. Tank 2a...Joint pipe 3...legs 3a...Side protector 4...Base 5...Handle 6...Main unit cover 7...Discharge port (for low pressure) 7a...Adjustment dial 8...Discharge port (for high pressure) 8a...Adjustment dial 9...Operation unit 10...Drain discharge device 10a...Upstream piping, 10b...Downstream piping 11...Drain valve 12...Sound deadening material 13...Container 20...Compression mechanism 21...Crankcase 22...No. 1 cylinder 23...Second cylinder 24...First piston 25...Second piston 26...First rod 27...Second rod 28...Air intake section 29...Plumbing 30...Electric motor 31...Motor shaft 32...Rotor 33...Stator 34...Cooling fan 35, 36...Bearings 37...Cooling fan 40...Valve device P1...Outlet closing pressure, P2...Inlet opening pressure, P3...Restart pressure, P4...Maximum pressure P5: Outlet opening pressure, P6: Inlet closing pressure 41...Inlet case 42...Outflow case 42a...Cylindrical support part 43...Connected case 44…Inlet 45...Inlet valve 45a...accommodating recess, 45b...support recess, 45c, 45d...air passage 45e...Bottom surface (pressure receiving surface), 45f...Bottom surface of large diameter part (pressure receiving surface) 46…Outlet 47...Outlet valve 47a...Spindle part, 47b...Flange part, 47c...Bottom surface 48...Passage hole 50... Inlet side biasing member 51... Outlet side biasing member 52, 53, 54, 55, 56...Sealing members 60...Clean air piping 70...Drain discharge device 71...Drain valve 71a...Upstream piping, 71b...Downstream piping 72...Clean air valve 72a...Upstream piping, 72b...Downstream piping

Claims

1. An air compressor, a tank for storing the generated compressed air; a drain discharge device that discharges drain water from the tank; a valve device that opens by utilizing the air pressure when the drain discharge device is opened and the air pressure in the tank drops to an outflow opening pressure to discharge the compressed air in the tank; an air compressor having a clean air pipe connected to the outlet of the valve device for directing compressed air in the tank to a portion of the air compressor;

2. 2. The air compressor according to claim 1, The valve device is an air compressor that closes by utilizing air pressure when the air pressure in the tank increases.

3. 3. The air compressor according to claim 1 or 2, the valve device has an inlet valve that opens and closes an inlet connected to the tank, and an outlet valve that opens and closes the outlet, An air compressor in which at least one of the inlet valve and the outlet valve is closed when the air pressure in the tank increases, and both the inlet valve and the outlet valve are opened when the air pressure in the tank decreases.

4. 4. The air compressor according to claim 3, When the air pressure in the tank rises and reaches an outlet closing pressure, the outlet valve closes, and when the air pressure reaches an inlet opening pressure higher than the outlet closing pressure, the inlet valve opens.

5. 5. The air compressor according to claim 3 or 4, When the air pressure in the tank drops and reaches the outlet opening pressure, the outlet valve opens, and when the air pressure reaches the inlet closing pressure which is lower than the outlet opening pressure, the inlet valve closes.

6. The air compressor according to any one of claims 1 to 5, a compression mechanism for generating the compressed air, An air compressor in which the outflow opening pressure is lower than a restart pressure at which the compression mechanism is restarted.

7. The air compressor according to any one of claims 1 to 6, The valve device has an inlet valve that opens and closes an inlet port connected to the tank, and the air compressor is attached to the tank with the inlet valve facing downward.

8. The air compressor according to any one of claims 3 to 5, An air compressor in which the inlet valve and the outlet valve are arranged coaxially and overlap each other.

9. 9. The air compressor according to claim 8, The valve device an inlet side case that has the inlet port and movably holds the inlet valve; an outflow side case that has the outflow port and movably holds the outflow valve; an inlet side biasing member that biases the inlet valve in a direction to close the inlet valve; An air compressor having an outlet-side biasing member that biases the outlet valve in a direction to open it.

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