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: An 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 a tank pressure during draining drain water from the tank. When the tank pressure drops to an opening pressure, a valve body 51 is moved by the energizing force of an energizing member 55 and then an outflow port 49 is opened. Thus, the compressed air in the tank 2 is jetted from a clean air pipe 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 9

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 for storing generated compressed air, a drain discharge device for discharging drain water from the tank, and a clean air chamber connected to the tank. The air compressor includes a valve device that opens in conjunction with an opening of the drain discharge device to discharge compressed air from the clean air chamber. The air compressor includes a clean air pipe connected to an outlet of the valve device to direct compressed air from the clean air chamber to a part of the air compressor.

[0008] Therefore, for example, when the drain discharge device is opened to discharge the drain water from the tank at the end of work, the air pressure in the tank drops, and the valve device opens, allowing the appropriate amount of compressed air (clean air) from the clean air chamber to be sprayed out from the clean air piping. The sprayed clean air blows away dust and other particles, efficiently cleaning the air compressor. [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] This is a vertical cross-sectional view of the valve device, showing the state in which the inlet valve has moved to a position where it closes the inlet port when the tank pressure drops. [Figure 9] 1 is a longitudinal cross-sectional view of the valve device, showing the state in which the outlet valve has been moved to a position that opens the outlet 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. DETAILED DESCRIPTION OF THE INVENTION

[0010] According to one embodiment, the valve device has a valve body that closes the inlet when the air pressure in the tank drops to an inlet closing pressure after the drain discharge device is opened. Therefore, the valve body moves due to the air pressure in the tank, closing the inlet. This allows the valve device to be closed in conjunction with the drain discharge device even in an environment without power, unlike, for example, when using a solenoid valve.

[0011] According to one embodiment, the valve body uses air pressure to open the outlet when the air pressure in the tank drops to an outlet opening pressure that is lower than the inlet closing pressure. Therefore, as the air pressure in the tank drops, the inlet is closed, and then the valve body is moved by the air pressure to open the outlet. This allows the valve device to open and close in conjunction with a drop in air pressure in the tank, allowing clean air to be sprayed, even in an environment without power, unlike, for example, when using a solenoid valve.

[0012] According to one embodiment, the valve device has a case body including an inlet valve that opens and closes an inlet connected to a tank, an outlet valve that opens and closes an outlet, and a chamber used as a clean air chamber. Therefore, as the air pressure in the tank decreases, the outlet valve moves to open the outlet, allowing clean air to flow out of the chamber.

[0013] According to one embodiment, the valve device includes a valve body, an inlet valve formed at one end of the valve body, and an outlet valve formed at the other end of the valve body. Therefore, the inlet valve and the outlet valve are integrally formed in one valve body. This allows the valve device to be made compact.

[0014] According to one embodiment, the valve device has a biasing member that biases the valve body in a direction to close the inlet, so that the inlet is closed when the valve body moves due to the biasing force of the biasing member.

[0015] According to one embodiment, the pressure-receiving area of ​​the outlet valve is larger than that of the inlet valve, so that the outlet valve is fully opened more quickly and reliably, thereby injecting an appropriate amount of clean air in a short time.

[0016] According to one embodiment, the valve device has a compression mechanism that generates compressed air. 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.

[0017] 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.

[0018] According to one embodiment, the valve device has a cylindrical case body with a chamber used as a clean air chamber, and a valve body that is disposed on the central axis of the case body and moves on the central axis using air pressure from the tank, thereby making the valve device compact. [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, for example, an outflow opening pressure P6, to allow 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 a cylindrical case body 43. The lower part (inlet side) of the case body 43 is closed by an inlet side cap 41. A seal member 44 provides an airtight seal between the case body 43 and the inlet side cap 41. The upper part (outlet side) of the case body 43 is closed by an outlet side cap 42. A seal member 45 provides an airtight seal between the case body 43 and the outlet side cap 42.

[0034] A cylindrical storage recess 46 is provided in the center of the top surface of the inlet-side cap 41. An inlet 47 is provided at the bottom of the storage recess 46. The inlet 47 is provided coaxially with the storage recess 46. A seal member 50 is provided at the inlet 47. The inlet 47 is connected to the tank 2 via a joint pipe 2a.

[0035] A cylindrical support recess 48 is provided in the center of the underside of the outflow side cap 42. The support recess 48 extends downward. The lower end of the support recess 48 is located close to the upper part of the storage recess 46. An outflow port 49 is provided on the inner circumferential side of the support recess 48.

[0036] The center of the accommodating recess 46 of the inlet-side cap 41 and the center of the supporting recess 48 of the outlet-side cap 42 coincide with the center of the case body 43. One valve body 51 is movably supported along the center of the accommodating recess 46 and the center of the supporting recess 48.

[0037] An inlet valve 52 is provided below the valve body 51. When the valve body 51 moves downward, the inlet valve 52 enters the inner circumferential side of the seal member 50, thereby closing the inlet port 47. When the valve body 51 moves upward, the inlet valve 52 moves out of the inner circumferential side of the seal member 50, thereby opening the inlet port 47. When the valve device 40 is attached to the tank 2 in an upright position, the inlet port 47 and inlet valve 52 are arranged facing downward. This prevents water in the tank 2 from entering the valve device 40 through the inlet port 47.

[0038] An outflow valve 53 is provided on the upper part of the valve body 51. A seal member 54 is attached to the outflow valve 53. When the valve body 51 moves upward, the seal member 54 enters the inner periphery of the outflow port 49, thereby closing the outflow port 49. When the valve body 51 moves downward, the seal member 54 disengages from the outflow port 49, thereby opening the outflow port 49.

[0039] The valve body 51 is provided with a flange portion 51a. A stepped portion 48a is provided on the inner periphery of the support recess 48. A single biasing member 55 is interposed between the flange portion 51a and the stepped portion 48a. A compression spring is used as the biasing member 55. The biasing member 55 biases the valve body 51 in a direction (downward) that closes the inlet 47.

[0040] A chamber (air chamber) is provided on the inner periphery of the case body 43 around the support recess 48. The chamber is used as a clean air chamber 56. The clean air chamber 56 is constantly connected to the inner periphery of the accommodating recess 46 and the inner periphery of the support recess 48. A plurality of slit-shaped air passages 46a are provided in the accommodating recess 46. The inner periphery of the accommodating recess 46 is constantly connected to the clean air chamber 56 via the air passages 46a and the upper opening. A plurality of air passages 48b are provided in the support recess 48. The inner periphery of the support recess 48 is constantly connected to the clean air chamber 56 via the air passages 48b and the lower opening.

[0041] A clean air pipe 60 is connected to the outlet 49. 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 other particles adhering to the intake section 28, particularly the filter, and cleans the air compressor 1.

[0042] 4, in the initial state where the air pressure (tank pressure) inside the tank 2 is zero, the valve body 51 is held in a downward movement end position by the biasing force of the biasing member 55. The downward movement end position of the valve body 51 is a position where the flange portion 51a abuts against the bottom of the accommodation recess 46. When the valve body 51 is held in the downward movement end position, the inlet valve 52 is inserted into the inner peripheral side of the seal member 50, so that the inlet port 47 is closed to the tank 2.

[0043] In the initial state where the valve body 51 is held in the lowest position, the seal member 54 of the outflow valve 53 is removed downward from the outflow port 49, leaving the outflow port 49 open. Therefore, in the initial state of the valve device 40, the clean air chamber 56 is open to the atmosphere and no compressed air is stored in it.

[0044] As shown in Figure 10, as the tank pressure increases or decreases from the initial state, the inlet valve 52 and outlet valve 53 move, automatically opening and closing the valve device 40. In Figure 10, the open states of the inlet valve 52 and outlet valve 53 are indicated by circles, and the closed states are indicated by crosses.

[0045] 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 47 is closed and the outlet 49 is open to an outlet closing pressure P1 (e.g., 1.5 MPa), the outlet 49 is closed. As shown in FIG. 5, the tank pressure (outlet closing pressure P1) acting on the lower surface 51b of the valve body 51 displaces the valve body 51 upward against the biasing member 55. This presses the seal member 54 of the outlet valve 53 against the outlet 49, closing the outlet 49. The outlet closing pressure P1 corresponds to the air pressure (outlet closing pressure) at which the outlet 49 is closed.

[0046] When the tank pressure rises to inlet opening pressure P2 (e.g., 2 MPa) while both the inlet 47 and the outlet 49 are closed, the inlet 47 opens. As shown in Figures 6 and 7, the tank pressure (inlet opening pressure P2) acting on the lower surface 51b of the valve body 51 moves the valve body 51 upward against the biasing force of the biasing member 55. This disengages the inlet valve 52 from the inner peripheral side of the seal member 50, opening the inlet 47.

[0047] When the inlet 47 is opened, the compressed air in the tank 2 flows into the clean air chamber 56 via the inlet 47 and the air passage 46a. At this stage, the outlet 49 is closed, so the clean air chamber 56 is instantly filled with an appropriate amount of compressed air.

[0048] With the inlet 47 open and the outlet 49 closed, the tank pressure rises to a maximum air pressure P4 (e.g., 4.5 MPa). The compressed air in the clean air chamber 56 also rises to air pressure P4. 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 49 of the valve device 40 is not opened.

[0049] After the work is completed, the power is shut off and the drain discharge device 10 is opened, thereby draining the tank 2. Compressed air is released through the drain discharge device 10 along with the water in the tank 2. This causes the tank pressure to decrease. As shown in Figures 8 and 10, when the tank pressure decreases to the inlet closing pressure P5 (e.g., 1.6 MPa), the inlet port 47 is closed. At this stage, the biasing force of the biasing member 55 becomes relatively greater than the tank pressure (inlet closing pressure P5) acting on the lower surface 51b of the valve body 51. Therefore, the valve body 51 moves downward due to the biasing force of the biasing member 55, and the inlet valve 52 enters the inner peripheral side of the seal member 50, thereby closing the inlet port 47 to the tank 2.

[0050] By closing the inlet 47, the compressed air in the clean air chamber 56 is sealed within the clean air chamber 56.

[0051] 9 and 10, when the tank pressure drops to the outflow opening pressure P6 (for example, 1.2 MPa), the air pressure pushing the valve body 51 upward further drops. As a result, the valve body 51 moves further downward due to the biasing force of the biasing member 55, and the seal member 54 of the outflow valve 53 disengages from the outflow port 49. This opens the outflow port 49.

[0052] In this embodiment, the pressure-receiving area of ​​the outflow valve 53 (the opening area of ​​the outflow port 49) is larger than the pressure-receiving area of ​​the inflow valve 52 (the cross-sectional area of ​​the inflow valve 52) (inner diameter d2 of the outflow port 49 > shaft diameter d1 of the inflow valve 52). Therefore, when the outflow valve 53 disengages from the outflow port 49, the valve body 51 moves downward more quickly, and the outflow port 49 is suddenly fully opened. This allows the appropriate amount of clean air to be sprayed in a short time.

[0053] By opening the outlet 49 while the inlet 47 is closed, an appropriate amount of compressed air in the clean air chamber 56 flows into the clean air piping 60 via the outlet 49. The compressed air (clean air) that flows into the clean air piping 60 is injected, for example, into the intake section 28 of the compression mechanism 20. This cleans the intake section 28 and its surroundings. By injecting an appropriate amount of clean air, the compressed air in the clean air chamber 56 is eliminated and the chamber is opened to the atmosphere.

[0054] When the drain discharge device 10 is opened and all of the compressed air in the tank 2 is released, the valve body 51 is returned to the lowermost position by the biasing force of the biasing member 55 as shown in FIG. 4, and the valve device 40 returns to its initial state.

[0055] According to the embodiment described above, the air compressor 1 has the valve device 40 that opens in conjunction with the opening of the drain discharge device 10 to allow the compressed air in the clean air chamber 56 to flow out. The clean air pipe 60 is connected to the outlet 49 of the valve device 40.

[0056] Therefore, for example, when the drain discharge device 10 is opened to discharge the water in the tank 2 at the end of work, if the air pressure in the tank 2 drops to the outflow opening pressure P6, the valve device 40 opens and an appropriate amount of compressed air (clean air) in the clean air chamber 56 is sprayed from the clean air piping 60. The sprayed clean air blows away, for example, dust and the like from the intake section 28 and its surroundings, thereby efficiently cleaning the air compressor 1.

[0057] According to the embodiment, the valve device 40 has a valve body 51 that uses air pressure to close the inlet 47 when the drain discharge device 10 is opened and the air pressure in the tank 2 drops. Therefore, the valve body 51 moves due to the air pressure in the tank 2, closing the inlet 47. As a result, unlike when a solenoid valve is used, for example, the valve device 40 is automatically closed in conjunction with the discharge of drain water even in an environment without power supply.

[0058] According to the embodiment, the valve body 51 uses air pressure to open the outlet 49 when the air pressure inside the tank 2 drops to the outlet opening pressure. Therefore, as the air pressure inside the tank 2 drops, the inlet 47 is closed, and then the valve body 51 moves due to the air pressure, opening the outlet 49. As a result, unlike when a solenoid valve is used, for example, the valve device 40 opens and closes in conjunction with a drop in air pressure inside the tank, allowing clean air to be sprayed even in an environment without power supply.

[0059] According to the embodiment, the valve device 40 has an inlet valve 52 that opens and closes the inlet 47 connected to the tank 2, an outlet valve 53 that opens and closes the outlet 49, and a case body 43 that has a chamber used as a clean air chamber 56. Therefore, when the air pressure in the tank 2 decreases, the outlet valve 53 moves to open the outlet 49, allowing clean air to flow out of the chamber.

[0060] According to the embodiment, the valve device 40 includes a valve body 51, an inlet valve 52 formed at one end of the valve body 51, and an outlet valve 53 formed at the other end of the valve body 51. Therefore, the inlet valve 52 and the outlet valve 53 are integrally formed in one valve body 51. This allows the valve device 40 to be made smaller.

[0061] According to this embodiment, the valve device 40 has a biasing member 55 that biases the valve body 51 in a direction that closes the inlet 47. Therefore, the biasing force of the biasing member 55 moves the valve body 51, thereby closing the inlet 47.

[0062] According to this embodiment, the pressure-receiving area of ​​the outflow valve 53 is larger than the pressure-receiving area of ​​the inflow valve 52. Therefore, the outflow valve 53 is fully opened more quickly and reliably, thereby injecting an appropriate amount of clean air in a short time.

[0063] According to the embodiment, the valve device 40 is always closed when the air pressure in the tank 2 is equal to or higher than the restart pressure P3. Therefore, when the air pressure in the tank 2 drops to an air pressure lower than the restart pressure P3 (for example, an outflow opening pressure P6), the valve device 40 opens and clean air is injected.

[0064] According to the embodiment, the valve device 40 has an inlet valve 52 that opens and closes the inlet 47 connected to the tank 2, and is attached to the tank 2 with the inlet valve 52 facing downward. Therefore, water is prevented from entering the valve device 40.

[0065] According to the embodiment, the valve device 40 has a cylindrical case body 43 equipped with a chamber used as the clean air chamber 56, and a valve body 51 disposed on the central axis of the case body 43 and movable on the central axis by utilizing the air pressure of the tank 2. Therefore, the valve device 40 is made compact.

[0066] 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.

[0067] 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.

[0068] Although a single stem structure in which the inlet valve 52 and the outlet valve 53 are provided on one valve body 51 has been exemplified, it may be changed to a double stem structure in which the inlet valve and the outlet valve are separate from each other.

[0069] The tank pressures P1, P2, P5, and P6 at which the inlet 47 and outlet 49 are opened and closed can be changed as appropriate by changing the area of ​​the pressure-receiving surfaces of the inlet valve 52 and outlet valve 53, or by changing the biasing force of the biasing member 55.

[0070] Although a configuration has been exemplified in which a chamber (air chamber) provided on the inner periphery of the case body 43 around the support recess 48 is used as the clean air chamber 56, a configuration in which a larger capacity clean air tank interposed between the inlet 47 and the outlet 49 is used as the clean air chamber instead of or in addition to such a chamber may also be used.

[0071] 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. [Explanation of symbols]

[0072] 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...1st 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: Inlet closing pressure, P6: Outlet opening pressure 41...Inlet cap 42...Outlet cap 43...Case body 44, 45...Sealing member 46... Storage recess 46a...Air passage 47...Inlet 48...Support recess 48a... stepped portion, 48b... air passage 49... Outlet 50...Sealing member 51...Valve body 51a... flange portion, 51b... lower surface (pressure receiving surface) 52...Inlet valve 53...Outlet valve 54...Sealing member 55... Urging member 56...Clean air chamber 60...Clean air 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 clean air chamber connected to the tank; a valve device that opens in conjunction with an opening of the drain discharge device to allow compressed air in the clean air chamber to flow out; an air compressor having a clean air line connected to the outlet of the valve assembly for directing the compressed air from the clean air chamber to a portion of the air compressor;

2. 2. The air compressor according to claim 1, The valve device is an air compressor having a valve body that closes the inlet when the drain discharge device is opened and the air pressure in the tank drops to an inlet closing pressure.

3. 3. The air compressor according to claim 2, The valve body is an air compressor that uses the air pressure to open the outlet when the air pressure in the tank drops to an outlet opening pressure that is lower than the inlet closing pressure.

4. The air compressor according to any one of claims 1 to 3, The valve device is an air compressor having a case body including an inlet valve that opens and closes an inlet connected to the tank, an outlet valve that opens and closes the outlet, and a chamber used as the clean air chamber.

5. 5. The air compressor according to claim 4, The valve device is an air compressor including a valve body, the inlet valve formed at one end of the valve body, and the outlet valve formed at the other end of the valve body.

6. 6. The air compressor according to claim 5, The valve device is an air compressor having a biasing member that biases the valve body in a direction to close the inlet.

7. 7. The air compressor according to claim 5 or 6, An air compressor in which the pressure-receiving area of ​​the outlet valve is larger than the pressure-receiving area of ​​the inlet valve.

8. The air compressor according to any one of claims 3 to 7, 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.

9. An air compressor according to any one of claims 1 to 8, 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.

10. An air compressor according to any one of claims 1 to 9, The valve device includes a cylindrical case body having a chamber used as the clean air chamber; An air compressor having a valve body that is disposed on the central axis of the case body and moves on the central axis using the air pressure of the tank.

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