Electromagnetic pump
The present invention provides an electromagnetic pump capable of highly precisely detecting operating positions of a moving member without enlarging the pump. An air-core detecting coil (53) for detecting reciprocating motion of the moving member (10) is fitted around a cylinder so as to be coaxial with electromagnetic coils (50a, 50b).
The present invention relates to an electromagnetic pump, more precisely relates to a compact electromagnetic pump used for sending a fluid, e.g., gas, liquid.
BACKGROUND TECHNOLOGY The inventor of the present invention invented a small and thin electromagnetic pump, wherein a moving member made of a magnetic material is reciprocally moved in a cylinder of a stator, pump chambers are respectively formed between both end faces of the cylinder and both side faces of the moving member extended in the moving direction thereof, electromagnetic coils are fitted around periphery of the cylinder, a fluid is introduced into one of the pump chambers from outside via a first valve and discharged outside via a second valve by applying electricity to the electromagnetic coils, and the fluid is introduced into and discharged from the other pump chamber by the same manner (see Patent Document 1). In
Patent Document 1: Japanese Patent Application No. 2002-286188
In the above described electromagnetic pump, a normal or abnormal motion of the moving member 101, which is accommodated in a cylinder section 109 whose both ends are closed by frames 107 and 108, and a normal or abnormal movable range of the moving member 101 are detected by various manners. For example, as shown in
In the electromagnetic pump shown in
The magnetic sensor 110 is easily influenced by magnetic fields produced by the electromagnetic coils 106a and 106b. Namely, a cycle time of the reciprocating motion of the moving member 101 is equal to that of variation of magnetic flux density leaked from the moving member 101. Further, a magnetizing cycle time of the electromagnetic coils is also equal. Therefore, it is difficult to judge if the variation of magnetic flux density detected by the magnetic sensor is caused by the reciprocating motion of the moving member 101 or magnetization of the electromagnetic coils 106a and 106b.
The present invention has invented to solve the above described problems, and an object is to provide an electromagnetic pump capable of highly precisely detecting operating positions of a moving member without enlarging the pump and minimizing influence of magnetic field produced by supplying electricity to an electromagnetic coil.
To achieve the object, the present invention has following structures.
The electromagnetic pump comprises: a cylinder; a moving member being movably accommodated in the cylinder, the moving member having a permanent magnet; an air-core electromagnetic coil being fitted around the cylinder, the electromagnetic coil reciprocally moving the moving member in the axial direction when electricity is supplied to the coil; and pump chambers for sending a fluid, the pump chambers being formed in the cylinder, said pump is characterized in that an air-core detecting coil for detecting reciprocating motion of the moving member is fitted around the cylinder so as to be coaxial with the electromagnetic coils.
In the electromagnetic pump, a plurality of the electromagnetic coils may be fitted around the periphery of the cylinder, and the detecting coils may be respectively provided close to axial end faces of the electromagnetic coils.
In the electromagnetic pump, yokes made of a magnetic material may be provided to axial end faces of the detecting coil or the axial end faces and an outer circumferential face thereof.
In the electromagnetic pump, frequency of induced voltage of the detecting coil may be twice as high as frequency of the reciprocating motion of the moving member.
In the electromagnetic pump, flow volume of the pump may be detected on the basis of the induced voltage detected by the detecting coil; flow volume of the pump greater than a prescribed value or not may be detected on the basis of a threshold value of the induced voltage detected by the detecting coil; a normal or abnormal reciprocating motion of the moving member may be detected on the basis of a threshold value of the induced voltage detected by the detecting coil; and motion of the moving member may be controlled on the basis of a threshold value of the induced voltage detected by the detecting coil.
Further, the induced voltage detected of the detecting coil may be detected in a detection range, in which variation of the induced voltage caused by magnetization of the electromagnetic coil is small.
EFFECTS OF THE INVENTIONIn the electromagnetic pump of the present invention, the air-core detecting coil for detecting reciprocating motion of the moving member is fitted around a periphery of the cylinder, in which many magnetic fluxes leak from the moving member, and coaxial with electromagnetic coils, so that the induced voltage of the detecting coil caused by the reciprocating motion of the moving member 101 can be increased, detecting accuracy can be improved and the motion of the moving member can be detected without enlarging the pump.
If the yokes made of the magnetic material are provided to the axial end faces and the outer circumferential face of the detecting coil, number of magnetic fluxes, which are generated from the moving member and which interlink the detecting coil, can be increased, so that the induced voltage of the detecting coil can be increased and detecting sensitivity can be improved.
If the frequency of the induced voltage of the detecting coil is twice as high as that of the reciprocating motion of the moving member, the frequency can be twice as high as that of a magnetic field produced by the electromagnetic coil, whose magnetizing frequency is equal to the frequency of the reciprocating motion of the moving member; the variation of magnetic flux density caused by the reciprocating motion of the moving member and the variation of magnetic flux density caused by the magnetization of the electromagnetic coil can be easily distinguished.
Further, the reciprocating motion of the moving member and the flow volume of the pump can be detected on the basis of the induced voltage of the detecting coil, and the motion of the moving member can be controlled.
BRIEF DESCRIPTION OF THE DRAWINGS
The preferred embodiments of the stator of the present invention will be explained with reference to the accompanying drawings. In the electromagnetic pump of the present embodiment, a moving member having a permanent magnet is accommodated in a cylinder, air-core electromagnetic coils are fitted around the cylinder, and the moving member is reciprocally moved in the axial direction by supplying electricity to the electromagnetic coils so as to send a fluid from pump chambers formed in the cylinder.
A typical structure of the electromagnetic pump will be explained with reference to
A closing member 16, which is made of a nonmagnetic material, e.g., plastic, covers an outer circumferential face of the magnet 12.
The closing member 16 covers the magnet 12 so as to prevent the magnet 12 from exposing and rusting and integrates the magnet 12 with the inner yokes 14a and 14b. The closing member 16 fills an outer periphery of the magnet 12, which is sandwiched by the inner yokes 14a and 14b, but an outer diameter of the closing member 16 is slightly shorter than those of the inner yokes 14a and 14b. By employing that closing member 16, the closing member 16 does not contact a grinding blade so that outer circumferential faces of the inner yokes 14a and 14b can be finished without damaging the grinding blade; and reduction of a space between the moving member 10 and the cylinder, which is caused by thermal expansion of the closing member 16 when the pump is used at high temperature, can be prevented even if a thermal expansion coefficient of the closing member 16 is greater than those of the inner yokes 14a and 14b, so that the pump can be stably operated.
Next, a stator of the electromagnetic pump will be explained with reference to
As described above, the axial end faces of the cylinder are closed by the frames 20a and 20b, and pump chambers 30a and 30b are respectively formed between inner faces of the frames 20a and 20b and both side faces of the moving member 10 extended in the moving direction thereof. The pump chambers 30a and 30b respectively correspond to spaces formed between both surfaces of the moving member 10 and the frame bodies 22a and 22b of the frames 20a and 20b. The moving member 10 slides on the inner face of the cylinder with air-tightly or liquid-tightly sealing the cylindrical section 24. To smoothly slide the moving member 10, the outer circumferential face of the inner yokes 14a and 14b are coated with a lubricative and rust-resistant coating agent. Further, means for preventing rotation of the moving member 10 may be provided.
Dampers 32 are provided to the end faces (inner faces) of the frame bodies 22a and 22b. The dampers 32 absorb shocks when the inner yokes 14a and 14b contact the end faces of the frame bodies 22a and 22b at end positions of a movable range of the moving member 10. Note that, the dampers 32 may be provided to end faces of the inner yokes 14a and 14b, which contact the frame bodies 22a and 22b, instead of the end faces of the frame bodies 22a and 22b.
An inlet valve 34a and an outlet valve 36a are provided in the frame body 22a of the upper frame 20a and connected to the pump chamber 30a. An inlet valve 34b and an outlet valve 36b are provided in the frame body 22b of the lower frame 20b and connected to the pump chamber 30b.
Inlet paths 38a and 38b are respectively formed in the frames 20a and 20b and connected to the valves 34a and 34b. Outlet paths 40a and 40b are respectively formed in the frames 20a and 20b and connected to the valves 36a and 36b. The path 38a of the upper frame 20a is connected to the path 38b of the lower frame 20b via a connection tube 42; the path 40a of the upper frame 20a is connected to the path 40b of the lower frame 20b via a connection tube 44. With this structure, the inlet paths and the outlet paths of the frames 20a and 20b are respectively connected to one inlet port 38 and one outlet port 40.
In
An outer yoke 52 encloses the electromagnetic coils 50a and 50b. The outer yoke 52 is made of a magnetic material so as to increase number of magnetic fluxes interlinking the electromagnetic coils 50a and 50b and effectively work an electromagnetic force to the moving member 10. Since the flange sections 15b are extended from the edges of the inner yokes 14a and 14b, which constitute the moving member 10, in the axial direction, magnetic resistance of a magnetic circuit, which is formed from the magnet 12 to the outer yoke 52 via the inner yokes 14a and 14b, can be reduced. With this structure, total number of magnetic fluxes from the moving member 10 can be increased (the magnetic circuit for passing magnetic fluxes can be securely formed), magnetic fluxes generated by the magnet 12 can be interlinked with the electric currents running through the electromagnetic coils 50a and 50b at a right angle so that a thrust force for moving the moving member 10 in the axial direction can be effectively generated. Further, mass of the moving member 10 is lower with respect to the thrust force, so that fast response can be performed and flow volume can be increased.
When the frames 20a and 20b are fitted together, the electromagnetic coils 50a and 50b and the outer yoke 52 can be coaxially arranged by fitting the outer yoke 52 in the grooves 28 of the frames 20a and 20b.
When an alternate current is supplied to the electromagnetic coils 50a and 50b, the moving member 10 is reciprocally moved (in the vertical direction) by electromagnetic forces generated by the electromagnetic coils 50a and 50b. Since the electromagnetic forces generated by the electromagnetic coils 50a and 50b move the moving member 10 in one direction and the opposite direction according to the directions of the electric current running through the electromagnetic coils 50a and 50b, the moving member 10 can be reciprocally moved with optional stroke by controlling time of supplying electricity to the electromagnetic coils 50a and 50b and the directions of the electric current running therethrough with a control section, not shown. When the moving member 10 contacts the inner faces of the frame bodies 22a and 22b, the shocks can be absorbed by the dampers 32.
The pumping action of the electromagnetic pump is performed by reciprocally moving the moving member 10 by the electromagnetic coils 50a and 50b, so that a fluid is alternately introduced into and discharged from the pump chambers 30a and 30b. Namely, in
In the electromagnetic pump of the present embodiment, the moving member 10 includes the inner yokes 14a and 14b having the flange sections 15b, and the inlet valves 34a and 34b and the outlet valves 36a and 36b are located close to the end faces of the moving member 10, so that the thin and compact pump can be produced. For example, a height of the electromagnetic pump is about 15 mm, and a width thereof is about 20 mm.
The electromagnetic pump of the present embodiment cab be used for sending any kinds of fluid, e.g., gas, antifreeze liquid. In case of using the pump as a liquid pump, if the pump has one moving member 10 and its sending pressure is low, a plurality of the moving members 10, each of which is constituted by the magnet 12 and the inner yokes 14a and 14b, may be used as a coupled moving member. By coupling a plurality of the moving members, a greater thrust force can be gained so that the electromagnetic pump having a prescribed sending pressure can be produced.
EXAMPLE 1 A structure and action of a detecting section, which detects the reciprocating action of the moving member of the electromagnetic pump, will be explained with reference to
Magnetic fluxes from the moving member 10 to the detecting coil 53 vary according to the positions of the moving member 10 as shown in
Another example of the detecting section, which detects the reciprocating action of the moving member of the electromagnetic pump, will be explained with reference to
An example for detecting flow volume of the electromagnetic pump on the basis of the reciprocating motion of the moving member will be explained with reference to
According to
An example for controlling the moving member of the electromagnetic pump will be explained with reference to
In a desired voltage range of the induced voltage, variation of the induced voltage, which is caused by magnetizing the electromagnetic coils 50a and 50b, should be small. Since the electromagnetic coils 50a and 50b are respectively provided on the upper side and the lower side of the detecting coil 53, the induced voltage is generated in the detecting coil 53 by variation of the electric current passing through the electromagnetic coils 50a and 50b.
In
In the electromagnetic pump shown in
Claims
1. An electromagnetic pump comprising: a cylinder; a moving member being movably accommodated in said cylinder, said moving member having a permanent magnet; an air-core electromagnetic coil being fitted around said cylinder, said electromagnetic coil reciprocally moving said moving member in the axial direction when electricity is supplied to said coil; and pump chambers for sending a fluid, said pump chambers being formed in said cylinder, characterized in,
- that an air-core detecting coil for detecting reciprocating motion of said moving member is fitted around said cylinder so as to be coaxial with said electromagnetic coils.
2. The electromagnetic pump according to claim 1, wherein a plurality of said electromagnetic coils are fitted around the periphery of said cylinder, and said detecting coils are respectively provided close to axial end faces of said electromagnetic coils.
3. The electromagnetic pump according to claim 1, wherein yokes made of a magnetic material are provided to axial end faces of said detecting coil or the axial end faces and an outer circumferential face thereof.
4. The electromagnetic pump according to claim 1, wherein frequency of induced voltage of said detecting coil is twice as high as frequency of the reciprocating motion of said moving member.
5. The electromagnetic pump according to claim 1, wherein flow volume of said pump is detected on the basis of the induced voltage detected by said detecting coil.
6. The electromagnetic pump according to claim 1, wherein flow volume of said pump greater than a prescribed value or not is detected on the basis of a threshold value of the induced voltage detected by said detecting coil.
7. The electromagnetic pump according to claim 1, wherein a normal or abnormal reciprocating motion of said moving member is detected on the basis of a threshold value of the induced voltage detected by said detecting coil.
8. The electromagnetic pump according to claim 1, wherein motion of said moving member is controlled on the basis of a threshold value of the induced voltage detected by said detecting coil.
9. The electromagnetic pump according to claim 1, wherein the induced voltage detected of said detecting coil is detected in a detection range, in which variation of the induced voltage caused by magnetization of said electromagnetic coil is small.
Type: Application
Filed: Aug 2, 2004
Publication Date: Oct 26, 2006
Inventor: Fumihiro Yaguchi (Chiisagata-gun)
Application Number: 10/566,470
International Classification: F04B 35/04 (20060101);