1. Field of the Disclosure
This disclosure pertains in general to voice coil. More particularly the disclosure relates to voice coils for driving membrane pumps used, for example, as sampling pumps in devices for patient monitoring, breath monitoring, anaesthesia monitoring, especially for medical ventilation monitoring and gas analyzers for monitoring gas composition in patient's breathing.
2. Description of the Related Art
The common way of designing a magnetic circuit, such as for a voice coils, is to make the magnet strictly cylindrical and if a pole shoe is used it is normally strictly cylindrical too. The pole shoe is used to collect the magnetic flux and redirect it to a pure radial direction. The density of the magnetic flux inside the steel parts (magnet cup and pole shoe) is depending of the section area of the parts. If it is too concentrated, the steel will be saturated and not able to conduct any more flux which leads to both leakage of magnetic flux (i.e. immediate magnetic material will be attracted) and limit the circuit's capacity. The cylindrical design of the magnet cup is also limiting the voice coil to have a mount of its free shaft end outside this cylindrical outer shape.
Hence, a new improved design of a magnetic circuit with better directing capability of the flux would be advantageous, especially if the same magnetic circuit has a small volume.
Accordingly, embodiments of the present disclosure preferably seek to mitigate, alleviate or eliminate one or more deficiencies, disadvantages or issues in the art, such as the above-identified, singly or in any combination by providing a device, system or method according to the appended patent claims for providing an improved magnetic circuit, such as in voice coil devices. These voice coils may be used in membrane pumps for patient monitoring, breath monitoring, anaesthesia monitoring, especially for medical ventilation monitoring and gas analyzers for monitoring gas composition in patient's breathing.
Disclosed herein are device, system and methods for providing the improved magnetic circuit.
According to one aspect of the disclosure, a magnetic circuit for a voice coil includes a magnet cup which has a one sided open cylindrical shape with a base, the base has an inner surface, a conical magnet which has a side with an at least partial conical shape, and a pole shoe which has a side with a recessed conical shape corresponding to the conical shape of the conical magnet, is disclosed. The magnet cup, the conical magnet and the pole shoe are stacked so that the conical magnet is centrally arranged on the base inside said magnet cup, then the pole shoe is arranged on the conical magnet so that the side with a recessed conical shape of said pole shoe is in contact with the side with a conical shape of said conical magnet. The stack is arranged such that an air gap is obtained between an inner wall surface of the magnet cup and the stacked conical magnet and said pole shoe.
The conical shape allows for a better distribution of magnetic flux inside the pole shoe. The design also improves the assembly of the magnetic circuit, as the conical shape allows for a self-alignment between the conically shaped parts.
In some examples of the disclosure, the base has an inner surface area with a partially conical shape protruding inward the magnet cup and the conical shape is at a central portion of the base of the cylindrical shape. Further, the conical magnet has a second side with a recessed conical shape corresponding to the conical shape of the inner surface area of base.
By having a conical shaped interface between the conical magnet and the inner surface of the magnet cup improves the distribution of the magnetic flux in the magnetic circuits.
Even further, by having all three parts conically shaped improves the self-alignment properties of the stack even further.
In some examples of the disclosure the base has an outer surface with a recessed conical shape.
Moreover, the conical shape of the base makes it possible to have a recessed outer surface of the base which creates a space which may be used to add a support for a free shaft end without adding any volume outside the cylindrical volume. Hence the voice coil may be smaller in size.
An airgap may be obtained between an inner surface area of the cylindrical shape of the magnet cup and the outer surface of the stacked conical magnet and the pole shoe. In this airgap a coil may be arranged.
In some examples is the coil entwined by self-adhesive lining. This design may take advantage of the limit space of the airgap. Hence smaller voice coils are possible to design.
In some further examples, a bore may go at least partially through the height of the stack. The bore is preferably arranged at the centre of the stack. In this bore a shaft may be arranged. The shaft may be connected to the coil so that when the coil moved the shaft will move. The motion of the shaft is a linear reciprocating stroke motion.
In some examples of the disclosure, the angle of the conical shapes spans the range 10 to 45 degrees.
Some materials of which the conical magnet may be made of are neodymium, samarium-cobalt, or alnico.
The pole shoe and the magnetic cup may be made of Ferromagnetic metals and/or alloys.
According to another aspect of the disclosure, a membrane pump is disclosed. The membrane pump comprises a magnetic circuit in accordance with the disclosure herein, a pump housing with a chamber having an open end. The membrane pump also includes a membrane element having a first area arranged to cover the open end of the chamber. The magnetic circuit is arranged and adapted to transfer a force by a stroke motion on the membrane.
In some examples of the membrane pump, the membrane element comprises a central section with a second area surrounded by a periphery section. The central section is thicker than the periphery section, and the second area of the central section is smaller than a third area of the open end of the chamber of which the central section is arranged over.
The advantages with this disclosed configuration is that it prevents the stroke from hitting the bottom of the chamber since a pump stroke is decelerated in a progressive way which not only makes the stop silent but also reduces the mechanical vibrations and keep them to a minimum. Further, the deceleration reduces the effective pump area of the membrane closer to the end of a stroke. Since the force of the stroke is constant, the pump becomes stronger closer to the end of the stroke.
In some further examples, the chamber may have bevelled inner walls. The central section of the membrane element is centrally arranged over the open end and the first area of the membrane element is larger than the third area of the open end.
Also, in some examples the pump housing may have an enlarged surface surrounding the open end of the chamber with a total area having at least the same size as the membrane element.
In some further examples of the disclosure, the membrane element is slidably clamped between the elongated surface of the pump housing and a second member of the pump housing.
The advantages with this configuration are that by holding a membrane element slidably fixed at a larger diameter than the actual working diameter (area) is that the membrane if free to move radial and stretch. Hence a longer pump stroke may be achieved (i.e. more volume can be pumped per stroke). Also a longer life of the membrane due to lower fatigue stress levels and more effective use of the available pump force may be obtained.
According to a further aspect of the disclosure, a method for assembling part to a magnetic circuit is disclosed. The method comprises, utilizing a conical design of the parts and a magnetic force of the magnetic circuit to allow different parts to self-orient.
The conical shape allows for a much easier assembly operation since the shape makes the parts self-orienting.
In this disclosure the word “conical” is defined both as strictly conical but also as a truncated cone.
It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.
These and other aspects, features and advantages of which examples of the disclosure are capable of will be apparent and elucidated from the following description of embodiments of the present disclosure, reference being made to the accompanying drawings, in which
Specific examples of the disclosure now will be described with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. The terminology used in the detailed description of the embodiments illustrated in the accompanying drawings is not intended to be limiting of the disclosure. In the drawings, like numbers refer to like elements.
The following description focuses on an embodiment of the present disclosure applicable to a magnetic circuit and to a voice coil. The voice coil is to be used as an actuator. For example, the voice coil may be used as an actuator for a membrane pump, such as a sampling pump in devices for patient monitoring, breath monitoring, anaesthesia monitoring, especially medical ventilation monitoring and gas analyzers for monitoring gas composition in patient's breathing. However, it will be appreciated that the description is not limited to this application but may be applied to many other systems where a fluid pump is required.
Additionally, when arranged in this fashion an airgap 11 is obtained between an inner surface area 20 of the cylinder and one side of the parts stacked inside the magnetic cup 7.
In this airgap, a coil (not seen in the figure) may be arranged. In some examples of the magnetic circuit, the coil is entwined by self-adhesive lining. This design may take advantage of the limit space of the airgap. Hence a smaller design of the magnetic circuit is possible.
Alternatively to the illustration in
By using a pole shoe 9 in the magnetic circuit 100 wherein the pole shoe 9 having a recessed conical shape in contact with a corresponding conical shape of an conical magnet, the magnetic flux inside the conicla magnet 8 is purely axial. Thus all of the flux is transferred into the pole shoe 9 and the magnet cup 7. Since the flux inside the pole shoe 9 is redirected towards the magnetic cup 7 the flux density is lower closer to the cylindrical centre than at the outer side. It is therefore an advantage to make the design conical since this also allows for a larger sized magnet, if desirable.
As illustrated in
On the other side, if also the magnets 8 other side (the one facing the magnet cup 7) is made conical and the base of the cup shape 7 too (like in
Some examples of magnetic materials, from which the conical magnet 8 may be made of, are neodymium, samarium-cobalt, or alnico. The pole shoe 9 and the magnetic cup 7 may be made of ferromagnetic metals and/or alloys.
Additionally, in some examples of the magnetic circuit 100 in
Additionally and/or alternatively if also the interface between the conical magnet 8 and the inner surface of the base of the magnetic cup is conical, such as illustrated in
The angles 10 and 15 may have the same gradient or the angles 10 and 15 may have different gradients.
The thickness proportions of between different part such as the wall of the magnetic cup 7 and the pole shoe 9 in regard to magnetic flux, depends on the grad and strength of the magnet. But it also depends on the function of the magnetic circuit and the cylindrical section area.
In some examples of the magnetic circuit 100, the stack of parts may have a bore 6 going at least partially through. The bore 6 is arranged at the centre of the stack. A shaft connected to the coil in the airgap 11 may be arranged in the bore 6. When driving a voltage or current through the coil shaft will move linear in a reciprocating stroke motion. This can be utilised as a pump head to exert a force on a membrane of a membrane pump.
Also, assembling a voice coil magnetic circuit requires much carefulness. It is absolutely necessary to assemble the magnet and the pole shoe concentric to make it work. This can be very tricky since the magnet forces always pulls the magnet and pole shoe towards the cylindrical wall of the magnet cup. By using the conical design of the parts, the magnetic circuit becomes self-oriented. The magnetic force will pull the conical parts together at the centre of the cup as intended. Hence this effect may be improved if all three parts have conical shapes.
A portion of the membrane may be slidably clamped between the second member 5 and the pump housing 1. This allows the membrane to move radial and stretch when a force is applied.
The advantages with this configuration are that by holding a membrane element slidably fixed at a larger diameter than the actual working diameter (area), the membrane is free to move radial and stretch. Hence a longer pump stroke may be achieved (i.e. more volume can be pumped per stroke). Also, due to the radial movement, the same pump volume can be maintained with less stretching which will increase the life of the membrane due to lower fatigue stress levels and more effective use of the available pump force may be obtained.
Additionally and/or alternatively, by designing the edge of the second pump housing member 5 (i.e. membrane fixing plate) to be conical or with one or more radii positioned in the area where the membrane element 32 becomes stiffer (thicker) it may also be possible to decelerate the pump stroke in a progressive way. This will make the stops, when the membrane element is in its turning point silent and also reduces the mechanical vibrations due to the progressive motion deceleration.
The pump further comprises a pump head 12. In this example, the pump head 12 is abutting the central section of the membrane element 33. Alternatively, in some examples, the pump head may be mechanically attached to the top of central section, such as inserted into the central section or a screw could be used to secure them together. When using a pump head 12 abutting the top of the central section an adhesive may be used between the top of the central section and the abutting area of the pump head 12 to affix the two members. Examples of adhesives may be, glue, sticky tape, etc.
In this example depicted in
In one example, the coil 13 is a circular cylinder structure, which is fixed on the pump head 12 and placed in an air gap. The air gap is enclosed by a magnetic cup with conical bottom 7, a conical magnet 8, such as a permanent magnet, and a one side conical pole shoe 9.
Additionally, in order to maximize the utilization of the magnetic field in the air gap and reduce the size of the pump 300, the coil 13 may be a skeletonless coil, entwined by self-adhesive lining. This design may take advantage of the limit space of the air gap, hence it's possible to design smaller membrane pumps 300.
In the example illustrated in
This design allows for a larger magnet, better distribution of the magnetic flux inside the pole shoe 9. Further, the conical shape provides better support for the free shaft of the pump head 12 without adding any volume outside of the cylinder volume. Thus the magnetic field is as large as possible when the coil 13 works in the air gap.
In
The pump cycle will produce a cycle of positive and negative pressure in the pump chamber 21. When pressure in the sealed room is negative, fluid will move through a pump inlet into the chamber 21. When pressure in the sealed room is positive, the pump 300 will move fluid out through an outlet.
In the example illustrated in
Also, the reciprocating motion of the pump head 12 is controlled by controlling the frequency of the voltage. Because the magnitude of reciprocating motion is dependent to the amplitude of the current, the collected flow size may be easily controlled by adjusting the amplitude of the voltage to the voice coil.
While several embodiments of the present disclosure have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the functions and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the present disclosure. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings of the present disclosure is/are used. Also, different method steps than those described above, performing the method by hardware, may be provided within the scope of the disclosure. The different features and steps of the disclosure may be combined in other combinations than those described. The scope of the invention is only limited by the appended patent claims
Number | Date | Country | Kind |
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12192847.7 | Nov 2012 | EP | regional |
12192859.2 | Nov 2012 | EP | regional |
12192889.9 | Nov 2012 | EP | regional |
The present application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application 61/726,962 filed Nov. 15, 2012 titled “PROGRESSIVE PUMP FORCE REGULATION,” U.S. Provisional Patent Application 61/726,965 filed Nov. 15, 2012 titled “EXTENDED ELASTICITY OF PUMP MEMBRANE WITH CONSERVED PUMP FORCE,” and U.S. Provisional Patent Application 61/727,012 filed Nov. 15, 2012 titled “Magnetic Circuit,” each of which applications is hereby incorporated herein by reference in their entirety. The present application also claims a priority benefit claims the benefit under 35 U.S.C. §119 of European Patent Application 12192847.7 filed Nov. 15, 2012 titled “PROGRESSIVE PUMP FORCE REGULATION,” European Patent Application 12192859.2 filed Nov. 15, 2012 titled “EXTENDED ELASTICITY OF PUMP MEMBRANE WITH CONSERVED PUMP FORCE,” and European Patent Application 12192889.9 filed Nov. 15, 2012 titled “Magnetic Circuit,” each of which applications is hereby incorporated herein by reference in their entirety. It is appreciated that the embodiments disclosed in each of the applications above may be combined in and/or utilized in combination with one another. For instance, one or more of the embodiments and/or one or more elements of embodiments described in conjunction with the “PROGRESSIVE PUMP FORCE REGULATION” application may be combined and/or used in combination with one or more embodiments or elements of embodiments described in conjunction with the “EXTENDED ELASTICITY OF PUMP MEMBRANE WITH CONSERVED PUMP FORCE” application and/or the “Magnetic Circuit” application.
Number | Date | Country | |
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61727012 | Nov 2012 | US | |
61726962 | Nov 2012 | US | |
61726965 | Nov 2012 | US |