Air pump

Abstract

[Problem] To provide an air pump that makes it possible to simply protect a circuit placed inside a casing without enlarging the external shape of the air pump overall. [Solution] An air pump (10) has an elastic sheet member (46) for partitioning an internal space (42) of a casing (20) into a first space part (42-1) in which a pump driving mechanism (22) is placed and a second space part (42-2) in which a control circuit (48) is placed. The elastic sheet member (46) has an opening part (50) which connects the first space part (42-1) and the second space part (42-2). The air pump (10) further comprises a blocking member (52) which is placed in a manner of blocking the opening part (50) of the elastic sheet member (46) from the second space part (42-2) side. The first space part (42-1) constitutes a portion of a flow passage (54) extending from an inlet (12) to an outlet (14). When the relative pressure of the first space part (42-1) with respect to the second space part (42-2) is less than or equal to a prescribed pressure, the elastic sheet member (46) is displaced toward the first space part (42-1) to open the opening part (50).

Description

air pump

[0001] The present invention relates to an air pump, and more particularly to an air pump having a control circuit disposed within a casing.

[0002] Typically, an air pump includes a pump drive mechanism disposed within a casing, and reciprocating the pump drive mechanism moves a diaphragm and a piston to draw in and discharge air. For example, Patent Document 1 discloses an air pump in which an alternating current (AC) voltage from an external power source is applied to a coil wound around a core to generate an alternating magnetic field, and the resulting magnetic force reciprocates a reciprocating member to drive the diaphragm. In this air pump, air is drawn in through an intake port and passes through the internal space of the casing in which the core and coil are disposed. The air then passes through a pump chamber whose volume periodically varies due to the diaphragm and is exhausted from an exhaust port. Air is allowed to flow around the core and coil to cool them.

[0003] In the past, the mainstream method was to apply an external AC voltage directly to the coil, but in recent years, air pumps that use inverter circuits to reduce power consumption have been increasing. For example, Patent Document 2 discloses an electric oil pump that is not an air pump but in which the motor for pumping is driven by an inverter circuit.

[0004] JP 2003-56466 A JP 2008-215088 A

[0005] In conventional air pumps, when the inverter circuit is placed inside the casing, dust and moisture contained in the air drawn in from the outside and dust generated by the pump drive mechanism may adhere to the control circuit, causing a malfunction. In the electric oil pump of Patent Document 2, a circuit board case for arranging the control circuit is provided separately from the pump case in which the motor is located, completely isolating the circuit from the motor and other components to protect the circuit from dust and other particles. However, providing a separate circuit board case tends to complicate the casing structure and make the entire pump larger and heavier.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an air pump that can easily protect a control circuit disposed within a casing without increasing the overall external size of the air pump.

[0007] That is, the present invention provides an air pump comprising: a casing having an intake port, an exhaust port, and an internal space; a pump drive mechanism at least a portion of which is disposed within the internal space; a control circuit for controlling the pump drive mechanism; an elastic sheet member which divides the internal space into a first space portion in which at least a portion of the pump drive mechanism is disposed, and a second space portion in which the control circuit is disposed, the elastic sheet member having an opening which connects the first space portion with the second space portion; and a closure member fixed to the casing and disposed so as to close the opening of the elastic sheet member from the side of the second space portion, wherein the first space portion forms part of a flow path extending from the intake port to the exhaust port, and when the relative pressure of the first space portion with respect to the second space portion falls below a predetermined pressure, the elastic sheet member deforms toward the first space portion to open the opening.

[0008] In this air pump, the space in which the inverter circuit and other control circuits are located is separated from the space in which the drive mechanism is located by an elastic sheet member, preventing the control circuit from being damaged by dust and moisture contained in the sucked air and dust generated by the pump drive mechanism. Furthermore, the elastic sheet member is configured to displace and open the opening when the relative pressure in the first space decreases, preventing the elastic sheet member from significantly deforming toward the first space due to the pressure difference between the first and second spaces. This prevents the elastic sheet from being damaged by excessive deformation or contact with the moving parts of the pump drive mechanism.

[0009] In addition, the closing member can have an axial portion extending through the opening of the elastic sheet member, and the axial portion can have a tapered surface that narrows in diameter from the second space portion toward the first space portion, so that the elastic sheet member engages with the tapered surface to close the opening.

[0010] With this configuration, it is possible to improve the sealing performance between the elastic sheet member and the closing member.

[0011] Furthermore, the casing may have a first casing member that defines the first space portion and a second casing member that defines the second space portion, and the elastic sheet member may be sandwiched between the first casing member and the second casing member to seal the space between the first casing member and the second casing member.

[0012] By using the elastic sheet member as a gasket in this way, it is possible to reduce the number of parts and simplify the casing structure.

[0013] The elastic sheet member may be formed of a sponge rubber sheet with a skin on one side.

[0014] Furthermore, the elastic sheet member can be positioned so that when there is no pressure difference between the first space portion and the second space portion, the elastic sheet member is pressed against the closing member to close the opening.

[0015] This configuration makes it possible to more reliably prevent unnecessary air from flowing from the first space to the second space when the air pump is not operating, and the resulting intrusion of dust and moisture.

[0016] The pump drive mechanism may also include an electromagnet arranged in the first space, a reciprocating member arranged in the first space and adapted to reciprocate by the magnetic force of the electromagnet, and a diaphragm attached to the reciprocating member.

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an air pump according to the present invention will now be described with reference to the accompanying drawings.

[0018] Fig. 1 is a perspective view of an air pump according to one embodiment of the present invention. Fig. 2 is a side view of the air pump of Fig. 1. Fig. 3 is a plan view of the air pump of Fig. 1. Fig. 4 is a plan sectional view taken along line A-A of Fig. 2. Fig. 5 is a front sectional view taken along line B-B of Fig. 3. Fig. 6 is a front sectional view taken along line CC of Fig. 3. Fig. 7 is a front sectional view of a state in which the first space is depressurized. Fig. 8 is a front sectional view of a state in which the first space is pressurized. Fig. 9 is a partial perspective sectional view of the air pump of Fig. 1.

[0019] 1 to 3, an air pump 10 according to one embodiment of the present invention is a vacuum pump that has an inlet 12 and an outlet 14, and draws in external air through the inlet 12 and discharges it through the outlet 14. The air pump 10 is fixed onto a fixing plate 18 via four vibration-isolating legs 16.

[0020] As shown in FIGS. 4 to 6 , the air pump 10 includes a casing 20 having an inlet 12 and an outlet 14, and a pump drive mechanism 22 disposed within the casing 20. The pump drive mechanism 22 includes an electromagnet 28 consisting of an E-shaped stator core 24 fixed to the casing 20 and a coil 26 wound around the stator core 24, and a reciprocating member 30 that reciprocates left and right as viewed in the figure. Two permanent magnets 32 are attached to the reciprocating member 30. Diaphragm holders 36 are fixed to both ends of the reciprocating member 30 with screws 34. The diaphragm holders 36 sandwich and hold the central portion of a diaphragm 38 between them. Applying an AC voltage to the electromagnet 28 using power supplied from a power line 40 causes the electromagnet 28 to generate an alternating magnetic field, and the magnetic force exerted by the permanent magnet 32 ​​on the reciprocating member 30 causes the reciprocating member 30 to reciprocate.

[0021] As shown in Fig. 5, the casing 20 includes a first casing member 20-1 on the upper side, a second casing member 20-2 on the lower side, a third casing member 20-3 on the left side, and a fourth casing member 20-4 on the right side. As shown in Fig. 4, the casing 20 further includes a fifth casing member 20-5 that covers the third casing member 20-3 from the outside, and a sixth casing member 20-6 that covers the fourth casing member 20-4 from the outside. The first casing member 20-1 and the second casing member 20-2 form an internal space 42 that communicates with the suction port 12. The third casing member 20-3 and the fourth casing member 20-4 each form a pump chamber 44 between themselves and their respective diaphragms 38.

[0022] As shown in FIGS. 5 and 6 , an elastic sheet member 46 is sandwiched and held between the first casing member 20-1 and the second casing member 20-2. This elastic sheet member 46 divides the internal space 42 of the casing 20 into an upper first space portion 42-1 and a lower second space portion 42-2. The electromagnet 28 and reciprocating member 30 of the pump drive mechanism 22 are disposed within the first space portion 42-1. The second space portion 42-2 is disposed with a control circuit 48 having an inverter circuit for controlling the operation of the pump drive mechanism 22. The inverter circuit converts power supplied from the power line 40 into an AC voltage suitable for application to the electromagnet 28 and supplies it to the electromagnet 28. Note that in this embodiment, the elastic sheet member 46 is configured as a single-sided skinned sponge rubber sheet, one side of which is formed from a high-density, air-resistant rubber material and the other side of which is formed from sponge-like rubber, but other types of elastic sheets may also be used. The elastic sheet member 46 is also used as a gasket that is crushed between the first casing member 20-1 and the second casing member 20-2 to seal the gap therebetween.

[0023] As shown in FIG. 6 , the elastic sheet member 46 has two openings 50 that connect the first space 42-1 and the second space 42-2. A closing member 52 is attached to the second casing member 20-2 so as to extend through the openings 50. The closing member 52 has an attachment portion 52-1 for attachment to the second casing member 20-2 and a shaft portion 52-2 that extends upward from the attachment portion 52-1. A tapered surface 52-3 that decreases in diameter from the second space 42-2 toward the first space 42-1 is formed on the outer periphery of the shaft portion 52-2. The elastic sheet member 46 engages with the tapered surface 52-3 of the closing member 52 around the openings 50, thereby closing the opening 50. The elastic sheet member 46 does not have any openings other than these openings 50, and therefore, when the two openings 50 are closed by the closing member 52, the first space portion 42-1 and the second space portion 42-2 are spatially separated.

[0024] Air drawn in through the intake port 12 passes through a flow path 54, which will be described below, to the exhaust port 14. As can be seen from FIG. 4 , air drawn in through the intake port 12 first enters the first space 42-1. Within the first space 42-1, the air passes around the electromagnet 28 of the pump drive mechanism 22, then passes through the first flow path 54-1 on both the left and right sides, and reaches just before the pump chamber 44. The air flowing around the electromagnet 28 effectively cools it. A one-way valve 58 is attached to the inlet 56 to the pump chamber 44. Another one-way valve 62 is attached to the outlet 60 of the pump chamber 44. When the diaphragm 38 is displaced by movement of the reciprocating member 30 and the volume of the pump chamber 44 expands, the one-way valve 58 attached to the inlet 56 opens, allowing air to enter the pump chamber 44 through the inlet 56. When the diaphragm 38 is displaced by the movement of the reciprocating member 30 and the volume of the pump chamber 44 decreases, the one-way valve 62 attached to the outlet 60 opens, allowing air to exit the pump chamber 44 through the outlet 60. When the volume of one pump chamber 44 increases due to the movement of the reciprocating member 30, the volume of the other pump chamber 44 decreases. Therefore, when air flows into one pump chamber 44, air is discharged from the other pump chamber 44. The air discharged from the pump chamber 44 passes through the second flow path 54-2 and then through the third flow path 54-3 shown in FIG. 9 to reach the buffer chamber 64. Note that while FIG. 9 only shows the third flow path 54-3 communicating with one pump chamber 44, a third flow path 54-3 communicating with the other pump chamber 44 is similarly provided. In this way, air discharged from the two pump chambers 44 enters the single buffer chamber 64. The air that reaches the buffer chamber 64 is discharged to the outside through the exhaust port 14.

[0025] As described above, the first space 42-1 constitutes part of the flow path 54 extending from the intake port 12 to the exhaust port 14. Therefore, the pressure within the first space 42-1 fluctuates depending on the operating state of the air pump 10. When the pressure within the first space 42-1 and the pressure within the second space 42-2 are the same, as shown in FIG. 6, the elastic force of the elastic sheet member 46 presses the periphery of the opening 50 against the tapered surface 52-3 of the closing member 52. This keeps the opening 50 closed. Therefore, at this time, there is no communication between the first space 42-1 and the second space 42-2. When the pump drive mechanism 22 is driven to start vacuum suction through the intake port 12, the pressure within the first space 42-1 gradually decreases. When the relative pressure of the first space 42-1 with respect to the second space 42-2 drops below a predetermined pressure, the pressure difference between the first space 42-1 and the second space 42-2 pulls the elastic sheet member 46 toward the first space 42-1 and deforms it, as shown in FIG. 7. This creates a gap between the periphery of the opening 50 and the tapered surface 52-3 of the closing member 52, and the first space 42-1 and the second space 42-2 are connected via the opening 50. Air in the second space 42-2 flows toward the first space 42-1 through the gap created in the opening 50. When the pressure in the second space 42-2 drops and the relative pressure of the first space 42-1 with respect to the second space 42-2 exceeds a predetermined pressure, the elastic force of the elastic sheet member 46 returns the elastic sheet member 46 to its original position, closing the opening 50, as shown in FIG. When the pressure in the second space 42-2 is below atmospheric pressure, and the pressure in the first space 42-1 increases relative to the second space 42-2 by, for example, stopping the operation of the pump drive mechanism 22 or opening the suction port 12 to the atmosphere, the elastic sheet member 46 is pressed toward the second space 42-2, as shown in Figure 8. As a result, the elastic sheet member 46 is pressed more firmly against the tapered surface 52-3 of the closing member 52. At this time, the opening 50 is closed by the closing member 52, so the air in the first space 42-1 does not flow into the second space 42-2 in the short term.However, the gap between the opening 50 and the closing member 52 and the connecting portion between the first casing member 20-1 and the second casing member 20-2 are not necessarily completely sealed, and the elastic sheet member 46 cannot completely block air, so over the long term air gradually flows into the second space 42-2. As a result, the pressures in the first space 42-1 and the second space 42-2 will eventually become substantially the same, as shown in FIG.

[0026] In the air pump 10 according to this embodiment, a control circuit 48 including an inverter circuit is disposed within the second space 42-2 within the casing 20, which is simply separated by an elastic sheet member 46. While the second space 42-2 is not completely sealed from the first space 42-1, air flow between the first space 42-1 and the second space 42-2 is restricted. In particular, air is essentially prevented from flowing from the first space 42-1 into the second space 42-2; even if air does flow, it only flows slowly through an extremely narrow gap. This prevents moisture and dust from entering the second space 42-2 along with the air. Furthermore, when the pressure in the first space 42-1 drops, air from the second space 42-2 flows into the first space 42-1 through the opening 50, preventing an excessive pressure difference between the first space 42-1 and the second space 42-2. If an excessive pressure difference occurs, there is a risk that the elastic sheet member 46 will deform significantly toward the first space 42-1 and interfere with the pump drive mechanism 22. In particular, if the elastic sheet member 46 comes into contact with the reciprocating member 30 while it is being driven, there is a risk that the elastic sheet member 46 will be worn down and torn by the reciprocating member 30. In this embodiment, the air in the second space 42-2 flows into the first space 42-1 through the opening 50, thereby preventing the elastic sheet member 46 from deforming significantly and thus preventing damage to the elastic sheet member 46.

[0027] The air pump 10 described above is a conventional air pump that does not include a control circuit including an inverter circuit and instead applies an external AC voltage directly to an electromagnet, but instead includes an elastic sheet member 46, a closing member 52, and a second space 42-2 for arranging the control circuit 48. More specifically, the gasket that was provided to seal the gap between the first casing member 20-1 and the second casing member 20-2 in the conventional air pump is replaced with the elastic sheet member 46, and the rubber member that constitutes the suction port when the conventional air pump is used as a compressor is replaced with the closing member 52 to produce the air pump 10 of this embodiment. In this way, the air pump 10 of this embodiment utilizes the structure of a conventional air pump (particularly the casing) while simply forming the partitioned second space 42-2 for arranging the control circuit 48. Furthermore, because the second space 42-2 utilizes a portion of the internal space 42 of the casing 20, the air pump 10 maintains the same external shape as the original air pump.

[0028] Although the above describes an embodiment of the present invention, the present invention is not limited to this embodiment. For example, while the air pump 10 is used as a vacuum pump in the above embodiment, it can also be used as a compressor. In this case, the suction port can be blocked, and a through-hole extending along the axial direction can be formed in the closing member and used as the suction port. When used as a compressor, a relatively large flow rate of air is sucked, and a suction port using a closing member is useful for reducing noise during suction. Furthermore, while the above embodiment is a diaphragm pump, other types of pumps, such as a piston type, can also be used. The number of openings formed in the elastic sheet member and the closing members that close them can be changed as desired, and can be one or more. Furthermore, the closing member may close the opening with a horizontal surface rather than a tapered surface. The elastic sheet member does not necessarily have to double as a gasket and may be disposed as a separate component from the gasket.

[0029] 10 Air pump 12 Intake port 14 Outlet port 16 Vibration-isolating leg 18 Fixing plate 20 Casing 20-1 First casing member 20-2 Second casing member 20-3 Third casing member 20-4 Fourth casing member 20-5 Fifth casing member 20-6 Sixth casing member 22 Pump drive mechanism 24 Stator core 26 Coil 28 Electromagnet 30 Reciprocating member 32 Permanent magnet 34 Screw 36 Diaphragm holding member 38 Diaphragm 40 Power supply line 42 Internal space 42-1 First space portion 42-2 Second space portion 44 Pump chamber 46 Elastic sheet member 48 Control circuit 50 Opening 52 Closing member 52-1 Mounting portion 52-2 Shaft portion 52-3 Tapered surface 54 Flow path 54-1 First flow path section 54-2 Second flow path section 54-3 Third flow path section 56 Inlet 58 One-way valve 60 Outlet 62 One-way valve 64 Buffer chamber

Claims

1. An air pump comprising: a casing having an intake port, an exhaust port, and an internal space; a pump drive mechanism at least a portion of which is disposed within the internal space; a control circuit for controlling the pump drive mechanism; an elastic sheet member which divides the internal space into a first space portion in which at least a portion of the pump drive mechanism is disposed and a second space portion in which the control circuit is disposed, the elastic sheet member having an opening which connects the first space portion with the second space portion; and a closing member fixed to the casing and disposed so as to close the opening of the elastic sheet member from the side of the second space portion, wherein the first space portion forms part of a flow path extending from the intake port to the exhaust port, and when the relative pressure of the first space portion with respect to the second space portion falls below a predetermined pressure, the elastic sheet member deforms toward the first space portion to open the opening.

2. An air pump as described in claim 1, wherein the closing member has a shaft portion extending through the opening of the elastic sheet member, the shaft portion having a tapered surface whose diameter decreases from the second space portion toward the first space portion, and the elastic sheet member engages with the tapered surface to close the opening.

3. An air pump as described in claim 1, wherein the casing has a first casing member that defines the first space and a second casing member that defines the second space, and the elastic sheet member is sandwiched between the first casing member and the second casing member to seal the space between the first casing member and the second casing member.

4. The air pump according to claim 3, wherein said elastic sheet member is formed of a sponge rubber sheet with a skin on one side.

5. An air pump as described in claim 1, wherein the elastic sheet member is positioned so that when there is no pressure difference between the first space portion and the second space portion, the elastic sheet member is pressed against the closing member to close the opening.

6. An air pump as described in claim 1, wherein the pump drive mechanism comprises an electromagnet disposed within the first space, a reciprocating member disposed within the first space and adapted to reciprocate by the magnetic force of the electromagnet, and a diaphragm attached to the reciprocating member.

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