1. Field of the Invention
The present invention relates to electromagnetic air pumps and, more particularly, to an electromagnetic air pump having a resinous air tank for temporarily storing compressed air.
2. Description of the Related Art
An electromagnetic air pump has a pump unit having an electromagnetic drive section to suck in air from the surroundings and to compress the air and an air tank for temporarily storing the compressed air from the pump unit to remove pulsation caused in the compressed air by the pump unit before discharging the compressed air.
Air compressed by the air pump is heated to a considerably high temperature by adiabatic compression. Therefore, the air tank needs to be capable of effectively performing heat dissipation. For this purpose, for example, a space for heat dissipation is provided between the air tank and the pump unit (see Patent Literatures 1 and 2 noted below).
Some air pumps have a resinous air tank to reduce the weight thereof. Such air pumps suffer, however, from the following problems.
Resinous air tanks are more difficult to dissipate heat from than metallic air tanks. Accordingly, one conventional practice is to assemble the air tank and the pump unit away from each other so that a space for heat dissipation is formed therebetween. However, it is a complicated operation to assemble the air tank to the pump unit as stated above. In addition, the resinous air tank is likely to be thermally deformed when used for a long period of time, and such deformation of the air tank may impair air-tightness relative to the air pump.
An object of the present invention is to provide an electromagnetic air pump using a resinous air tank to achieve a weight reduction and yet free from the above-described problems.
The present invention provides an air pump including a pump unit and an air tank for temporarily storing air compressed in the pump unit before discharging the compressed air. The air tank has a resinous tank body having a top wall on which the pump unit is placed, and a peripheral wall extending downward from the top wall. The tank body has a downward facing opening. The air tank further has a metallic bottom wall member engaged with the bottom surface of the peripheral wall so as to close the opening of the tank body. Bolts are passed through the metallic bottom wall member and into a metallic part of the pump unit and tightened to securely connect the pump unit and the air tank to each other.
In this air pump, the resinous tank body is put between the metallic bottom wall member and a metallic part of the pump unit, and bolts are passed through from the bottom wall member and into the metallic part of the pump unit and tightened to securely connect the pump unit and the air tank to each other. Therefore, the resinous tank body can be firmly and easily secured to the pump unit with satisfactory sealing properties between the bottom wall member and the tank body. Accordingly, the tank body can be prevented from becoming deformed even if the air pump is used for a long period of time. In addition, disassembling and reassembling are easy when maintenance is performed on the air pump.
In addition, heat generated in the tank can be efficiently dissipated through the metallic bottom wall member, and the air pump can be made so that the heat of the air tank is not easily transmitted to the pump unit.
Specifically, the peripheral wall may have a double-wall structure comprising an outer wall, an inner wall, and at least one air gap between the outer and inner walls. The double-wall structure suppresses the transmission of vibration noise of air from the air tank to the outside.
Specifically, the at least one air gap may comprise a plurality of air gaps spaced from each other in the circumferential direction of the peripheral wall, and an intermediate wall may be provided between adjacent air gaps to connect together the outer and inner walls. This is for attaining a noise reduction effect of the peripheral wall and for maintaining the strength of the peripheral wall.
Further, the arrangement may be as follows. The tank body has a partition wall extending downward from the top wall thereof to partition the interior of the tank body into a plurality of spaces. The partition wall has an air passage formed therein to allow air introduced into the air tank to flow toward an air outlet of the air pump through the plurality of spaces. The partition wall is shorter in height than the peripheral wall. Between the partition wall and the bottom wall member is provided a seal member that is more pliable than the resin used to form the tank body. The reason why a partition wall with an air passage is provided is to reduce the pulsation of air discharged from the air tank. The reason why the partition wall is shorter than the peripheral wall and a relatively pliable seal member is provided is as follows. If the partition wall has the same height as that of the peripheral wall and is abutted directly against the bottom wall member to seal therebetween, sealing cannot be completed unless the lower surface of the peripheral wall and the lower surface of the partition wall are completely flush with each other. Consequently, the production process becomes difficult. For this reason, a relatively pliable seal member is interposed between the partition wall and the bottom wall member to allow the desired sealing to be attained even if the respective lower surfaces of the partition wall and the peripheral wall are not completely flush with each other. In addition, it is possible to obtain the effect of suppressing vibration transmitted from the pump unit to the bottom wall member by the arrangement in which the partition wall is not abutted directly against the bottom wall member, but a seal member more pliable than the partition wall is interposed between the partition wall and the bottom wall member.
For similar purposes, the inner wall may also be made shorter than the outer wall, and a seal member more pliable than the inner wall and the partition wall may be provided between the inner wall and the partition wall, on the one hand, and the bottom wall member, on the other.
In this case, the seal member may be a sheet-shaped member stacked on the inner surface of the bottom wall member so that the inner wall and the partition wall sealingly engage with the seal member. Provision of the seal member stacked on the inner surface of the bottom wall member makes it difficult for the pulsation of air entering the air tank to be transmitted to the bottom wall member.
Further, the above-described air pump may be arranged as follows. The pump unit includes a piston assembly of a pair of pistons and an armature connecting together the pair of pistons in the state that the pair of pistons are aligned with each other in the axial direction of the pistons, and a pair of electromagnets provided at the opposite sides, respectively, of the armature. When an alternating electric current is applied thereto, the electromagnets generate an alternating magnetic field to reciprocate the armature in the axial direction of the pistons. The pump unit further includes a pump casing having a pair of cylinder chambers slidably accommodating the pair of pistons, respectively, and a drive chamber accommodating the armature extending between the pair of cylinder chambers and the electromagnets. The pump casing has a peripheral wall defining the drive chamber. The peripheral wall of the pump casing has an electromagnet-loading opening extending through a bottom wall portion thereof to allow the electromagnets to be loaded into the drive chamber from the outside of the peripheral wall. The top wall of the air tank is sealingly engaged with the bottom wall portion of the pump casing to close the electromagnet-loading opening.
With the above-described arrangement, the electromagnet-loading opening can be closed by the air tank without separately providing a member for closing the electromagnet-loading opening.
In this case, the arrangement may further be as follows. The bottom wall portion of the pump casing has an air discharge opening for discharging air compressed in the pump unit to the outside of the pump casing. The air tank has an air inlet disposed to face the air discharge opening. A seal member is provided between the top wall of the air tank and the bottom wall portion of the pump casing. The seal member surrounds an air passage between the air discharge opening and the air inlet.
One embodiment of an air pump according to the present invention will be explained below in detail with reference to the accompanying drawings.
As illustrated in the figures, an air pump 10 according to the present invention has a pump unit 12 for sucking in and compressing air from the surroundings and an air tank 20 for temporarily storing the compressed air from the pump unit 12 to suppress pulsation caused by reciprocating motion of pistons 16 of the pump unit 12 before discharging the compressed air. The air pump 10 further has a housing 24 accommodating the pump unit 12 and the air tank 20.
First, these constituent elements and the overall structure will be outlined below.
First, the pump unit 12 has a casing 17 having a pair of cylinder chambers 14 disposed in bilateral symmetry as seen in
The electromagnetic drive unit 18 has an armature 34 connecting the pair of pistons 16 to each other and having plate-shaped permanent magnets 32 disposed in bilateral symmetry as seen in
The air tank 20 has a resinous tank body 44 having a top wall 40 of a rectangular shape in plan view, on which the pump unit 12 is placed. The tank body 44 further has a peripheral wall 42 extending downward from the top wall 40. Thus, the tank body 44 has a downward facing opening. The air tank 20 further has a metallic bottom wall member 46 installed to close the opening of the tank body 44. The bottom wall member 46 has a plurality of bolts 47 passed through a peripheral edge portion thereof. The bolts 47 are thread-engaged with the metallic casing 17 of the pump unit and tightened to clamp the resinous tank body 44 between the metallic bottom wall member 46 and the casing 17.
Specifically, the housing 24, which accommodates the pump unit 12 and the air tank 20, has a flat-bottomed pan-shaped bottom part 50, a housing body 52 installed on the bottom part 50, and a cover 54 attached to the top of the housing body 52. An air intake passage 58 with a rainwater trap portion 56 is provided between the cover 54 and the housing body 52. Air introduced into the housing 24 through the rainwater trap portion 56 passes into the inside of the housing through the filter 38 provided in the top of the housing body 52. The bottom part 50 of the housing 24 supports the air tank 20 through support studs 66 made of a damper rubber.
The above is the outline of the air pump according to the present invention. The following is an explanation of the details of the air pump.
As shown in
The casing body 26 has a noise reduction wall 26-9 standing on the upper surface of the top wall 26-3. Specifically, the noise reduction wall 26-9 comprises, as shown in
The air tank body 44 has a peripheral wall 42 having a double-wall structure comprising, as shown in
The peripheral wall 42 is provided with a plurality of screw-receiving holes 42-7 vertically extending therethrough. The bolts 47 inserted through the peripheral portion of the bottom wall member 46 are passed through the screw-receiving holes 42-7 and thread-engaged with the bottom portion of the casing 17, thereby clamping the air tank body 44 between the bottom wall member 46 and the bottom portion of the casing 17. The partition wall 42-4 in the center of the air tank body 44 is also provided with a screw-receiving hole 42-8. A bolt 49 inserted through the center of the bottom wall member 46 is passed through the screw-receiving hole 42-8, and the distal end of the bolt 49 is thread-engaged with a nut 49-1 fitted into the upper end of the screw-receiving hole 42-8, thereby securing the bottom wall member 46 to the tank body 44. The bottom wall member 46 has a sheet-shaped seal member 43 stacked on the upper surface thereof inside the outer wall 42-1 of the air tank body 44. The seal member 43 is made of a material more pliable than the resin used to form the air tank body 44. Thus, the inner wall 42-2 and partition walls 42-4 of the air tank body 44 sealingly clamp the seal member 43 between themselves and the bottom wall member 46. As shown in
Number | Date | Country | Kind |
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JP2009-019849 | Jan 2009 | JP | national |
This application is a continuation of PCT/JP2010/051234 filed on Jan. 29, 2010, which claims priority to Japanese Application No. 2009-019849 filed on Jan. 30, 2009. The entire contents of these applications are incorporated herein by reference.
Number | Date | Country | |
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Parent | PCT/JP2010/051234 | Jan 2010 | US |
Child | 13193102 | US |