Linear compressor with permanent magnets
This invention provides a compressor with brushless single-phase linear motor, which includes a movable cylinder associated with a permanent magnet array, at least a stationary electromagnetic winding set and a pair of stationary pistons. A partition plate is disposed in the movable cylinder to form a first sub-cylinder and a second sub-cylinder. The front ends of the pair of the stationary pistons are respectively placed in either of two openings of the movable cylinder at its two ends. An alternate current applied to the stationary electromagnetic winding set to generate alternately attracting/repelling forces to the permanent magnet array. The movable cylinder is hence alternately pushed forward and backward. The volumes of the first and second sub-cylinders are changed to compress air in the first sub-cylinder or the second sub-cylinder.
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1. Field of the Invention
The present invention relates to the field of mechanical devices for the pumping of fluids which are powered by a brushless linear motor with permanent magnets.
2. Description of the Related Art
The oxygen therapeutic devices include oxygen concentrator, compressing oxygen bottle, oxygen regulator, liquefied oxygen, flow regulator etc. Oxygen therapeutic devices are primarily used for chronic obstructive pulmonary disease, oxygen supply during sleep and hypoxemia. The patients can be classified into mobile and immobile. 80% patients need oxygen for 1.5 to 2.0 liter per minute and for 15 hours every day. The mobile patients may need portable and stationary oxygen devices in their daily life. When they do exercise, the demanded oxygen flow rate is increased to 4˜6 liters per minute. The oxygen concentrator extracts oxygen from air, whose key elements is therapeutic-level compressor, which requires advanced technique and innovative electro-mechanic design to meet various demands of the mobile patients.
US Publication Application No. 2006/0216170A1 provides a compressor with a cylinder of single chamber, which employs a magnetic armature and a piston as motor and electromagnetic winding sets as stator. When an AC voltage is applied to the electromagnetic winding sets, a magnetic force is intermittently induced between the electromagnetic winding sets to attract the magnetic armature to move forward so as to push the piston connected with a rear end of the magnetic armature forward. A spring disposed at a front end of the magnetic armature is compressed. When the magnetic force disappears, the spring is restored, and hence pushing the magnetic armature and piston back to the original positions. This compressor employs the magnetic force and restore of the spring as the driving force of the motor, which is smaller. Moreover, the compressor has a longer length and thus a larger size. This compressor employs the single-chamber cylinder with a fixed volume. The cross-sectional area and flow quantity of the cylinder are small. The application of this kind of compressor is limited.
U.S. Pat. No. 6,015,270 provides a compressor, which employs a movable single-chamber cylindrical piston with a plurality of magnetic flux carrying means (permanent magnet arrays) as a motor and a stationary hollow cylindrical motor body with a plurality of electromagnetic winding coils as a stator. When the plurality of drive coils sequentially excited by a multiphase current to produce force on the stator, the cylindrical piston can be moved. By changing the phase of the current applied to each coils alternately, the cylinder can be moved forward and backward. Because this compressor use the electronically controlled multiphase linear motor as the driving force, a control circuitry is required. Moreover, the design of the compressor is complex and difficult to build and has a lower power density.
SUMMARY OF THE INVENTIONThe present invention provides a fluid pumping apparatus with less noise, size and weight while maintaining its operation performance to meet the demands of long-term respiratory care and quality of the patients' life.
The present invention provides a brushless linear compressor with permanent magnets mainly comprising a movable cylinder, at least one stationary electromagnetic winding set and a pair of stationary pistons. The movable cylinder has at least one permanent magnet array and a partition plate, and having one opening formed at each of two ends thereof. The partition plate is disposed in the movable cylinder to separate the movable cylinder into a first sub-cylinder and a second sub-cylinder. The permanent magnet array is disposed at an outer wall of the movable cylinder in an axial direction thereof. The magnet array includes a plurality of permanent magnets wherein adjacent magnets are magnetized oppositely. The stationary electromagnetic winding set is disposed at outside of the movable cylinder relative to the permanent magnet array. The stationary electromagnetic winding set includes a plurality of sub-winding sets. The sub-winding sets are wound in a way that the stationary electromagnetic winding set generates alternate magnetic fields to attract or repel the permanent magnet arrays to move the movable cylinder along the axial direction when an alternate current is applied. Each of the stationary pistons has a main chamber with a front end thereof placed in the opening of one of the two ends of the movable cylinder and a rear end of the main chamber becomes open. The main chamber has a plurality of sub-chambers. At least two check valves are disposed to obtain unidirectional inflow and outflow in the movable cylinder. Determining by the phase of the input current, the movable cylinder moves forward or backward along the axial direction, and accordingly compressing the volume of the first or second sub-cylinders.
The present brushless and linear design has fewer elements and better operation performance. In addition, the movable cylinder associated with the motor saves the extended length required by other moving piston designs and thus make the pumping assembly more compact.
The brushless linear compressor with permanent magnets of the present invention will be described in detail in accordance with the following preferred embodiments and accompanying drawings.
The present invention is provided with the sliding rails at the inner wall of the outer shell 10 to guide the movement of the movable cylinder 12 along the axial direction in the outer shell 10. The present invention can also employ the stationary pistons 16a and 16b to guide the movement of the movable cylinder 12 along the axial direction in the outer shell 10.
The operation of the brushless linear compressor with permanent magnets 1 of the present invention will be described in detail accompanying with
The brushless linear compressor with permanent magnets 1 of the present invention can be directly driven by the household alternate current source. The direction of the magnetic fields of the sub-winding sets of the pair of the stationary electromagnetic winding sets 14a and 14b is alternately changed with the phase of the alternate current source. The movable cylinder 12 is attracted or repelled to move forward or backward to alternately compress the volumes of the first sub-cylinder 120a and the second sub-cylinder 120b. Compressed gas, such as high pressure air, is generated in the first sub-cylinder 120a and the second sub-cylinder 120b, alternately. The operation of the present invention as an air compressor is described in the following. As illustrated in
The partition plate 122 inside the movable cylinder 12 is detachable. The air compression ratio inside the movable cylinder 12 is adjustable by the replacement of the partition plate 122 of different thicknesses. The air compression ratio is defined as the ratio of the maximum expanded volume to the minimum compressed volume of the first sub-cylinder 120a or the second sub-cylinder 120b. The pressure and flow quantity of the compressed air are thereby adjustable. Moreover, the present invention can be incorporated with a Pulse-Width-Module frequency controller and a sensing circuit to precisely control the high air pressure and its flow rate.
A pair of permanent magnet arrays 764a and 764b is disposed at the outer wall of the second cylinder 76. Each of the permanent magnet arrays 764a and 764b includes a plurality of permanent magnets wherein adjacent magnets are magnetized oppositely. A magnetic-conductive material 766a, for example silicon steel, is preferably disposed between the outer wall of the second movable cylinder 76 and the corresponding permanent magnet array 764a to reduce the magnetoresistance of the permanent magnet array 764a. Similarly, a magnetic-conductive material 766b, for example silicon steel, is preferably disposed between the outer wall of the second movable cylinder 76 and the corresponding permanent magnet array 764b to reduce the magnetoresistance of the permanent magnet array 764b. A detachable second partition plate 762 is disposed at a location, for example a central location, inside the second movable cylinder 76 to separate the second movable cylinder 76 into a third sub-cylinder 76a and a fourth sub-cylinder 76b. The pair of the second stationary electromagnetic winding sets 78a and 78b is disposed outside of the second movable cylinder 76 corresponding to one of the permanent magnet arrays 764a and 764b, respectively. The design of the second stationary electromagnetic winding sets 78a and 78b is the same with the design of the stationary electromagnetic winding sets 14a and 14b of the first preferred embodiment. Each of the second stationary electromagnetic winding sets (78a or 78b) includes a stator base 780 and windings 782. Each winding wound on a lateral branch of the stator base 780 forms a sub-winding set. The second stationary electromagnetic winding sets 78a and 78b generate alternate magnetic fields when the current is applied. The second stationary piston 82 includes a second main chamber divided into two sub-chambers 822 and 824. A front end of the second stationary piston 82 is placed in the opening of one end of the second movable cylinder 76. Two check valves 826 and 828 with different flow directions are disposed at the front end of the second movable cylinder 76 corresponding to the second sub-chambers 822 and 824, respectively.
The third stationary piston 84 includes a third main chamber divided into two third sub-chambers 843 and 844. A front end 841 of the third stationary piston 84 is placed into the opening of the other end of the first movable cylinder 72. A rear end 842 of the third stationary piston 84 is placed in the opening of the other end of the second movable cylinder 76. As such, the first movable cylinder 72 and the second movable cylinder 76 are connected together via the third stationary piston 84. Two check valves 845 and 846 with different flow directions are disposed at the front end 841 of the third stationary piston 84 corresponding to the third sub-chambers 843 and 844, respectively. Two check valves 847 and 848 with different flow directions are disposed at the rear end 842 of the third stationary piston 84 corresponding to the third sub-chambers 843 and 844, respectively. An upper part of the third sub-chamber 843 is formed with an outlet passage 849 and a lower part of the third sub-chamber 844 is formed with an inlet passage 850.
In the third preferred embodiment, it is preferable that the arrangement of the magnetic fields generated by the pair of the first stationary electromagnetic winding sets 74a and 74b is opposite to the arrangement of the magnetic fields generated by the pair of the second stationary electromagnetic winding sets 78a and 78b. That is, the winding direction and the current direction of the first stationary electromagnetic winding sets 74a and 74b are opposite to the second stationary electromagnetic winding sets 78b and 78b. As shown in
As show in
In the third preferred embodiment, when the current is applied to the first and the second brushless linear motors, the compressed air generated by the first movable cylinder 72 and the second movable cylinder 76 enters the outlet passage 849 at the same time. The flow rate of the compressed air is doubled. Moreover, the first movable cylinder 72 and the second movable cylinder 76 move relative to each other at the same time. The vibration generated by both brushless linear motors is canceled by each other. The noise is reduced as well.
The remaining constitution elements of the brushless linear compressor with permanent magnets of the third preferred embodiment are the same with that of the first preferred embodiment as shown in
The remaining constitution elements of the forth and fifth preferred embodiments are the same with that of the first preferred embodiment. The alternations and modifications of the sliding rails and the permanent magnet arrays as described in the above preferred embodiments are also applicable in the forth and fifth preferred embodiments.
While the invention has been described by way of examples and in terms of preferred embodiments, it is to be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims
1. A linear compressor with permanent magnets comprising:
- a movable cylinder having at least one permanent magnet array and a partition plate, said movable cylinder having one opening formed at each of two ends thereof, said partition plate disposed in said movable cylinder to separate said movable cylinder into a first sub-cylinder and a second sub-cylinder, said permanent magnet array disposed at an outer wall of said movable cylinder in an axial direction thereof and including a plurality of permanent magnets in which adjacent magnets are magnetized oppositely;
- at least one stationary electromagnetic winding set disposed at outside of said movable cylinder relative to said permanent magnet array, said stationary electromagnetic winding set including a plurality of lateral branches and a plurality of sub-winding sets, wherein said sub-winding sets are wound in a way that said stationary electromagnetic winding set generates alternate magnetic fields to attract or repel said movable cylinder to move along the axial direction when an alternate current is applied to said stationary electromagnetic winding set; and
- a pair of stationary pistons, each of said stationary pistons having a main chamber with a front end thereof placed in the opening of one said end of said movable cylinder and a rear end of said main chamber becoming open, said main chamber having a plurality of sub-chambers and at least two check valves with different flow directions disposed at said front end thereof respectively corresponding to one of said sub-chambers;
- wherein said movable cylinder moves forward or backward along the axial direction in response to a phase of the current applied to said stationary electromagnetic winding set, and accordingly changing volumes of said first sub-cylinder and said second sub-cylinder.
2. The compressor of claim 1, further comprising an outer shell for accommodating said movable cylinder, said stationary electromagnetic winding set and the pair of said stationary pistons, wherein said movable cylinder and the pair of said stationary pistons are disposed in a way along an axial direction of said outer shell, and said stationary electromagnetic winding set is disposed at an inner sidewall of said outer shell.
3. The compressor of claim 2, further comprising at least a pair of sliding rails respectively disposed at two opposite positions of one inner wall of said outer shell along the axial direction thereof for guiding the movement of said movable cylinder.
4. The compressor of claim 1, wherein the pair of said stationary pistons guides the movement of said movable cylinder.
5. The compressor of claim 1, wherein said movable cylinder has a plurality of said permanent magnet arrays symmetrically disposed at the outer wall of said movable cylinder, and a plurality of said stationary electromagnetic winding sets are disposed at outside of said movable cylinder respectively corresponding to one of said permanent magnet arrays.
6. The compressor of claim 5, wherein said permanent magnet arrays are disposed at the outer wall of said movable cylinder in a geometric arrangement of cross shape, X shape or triangular shape.
7. The compressor of claim 2, wherein said movable cylinder has a plurality of said permanent magnet arrays symmetrically disposed at the outer wall of said movable cylinder, and a plurality of said stationary electromagnetic winding sets is disposed at the inner wall of said outer shell respectively corresponding to one of said permanent magnet arrays.
8. The compressor of claim 7, wherein said permanent magnet arrays are disposed at the outer wall of said movable cylinder in a geometric arrangement of cross shape, X shape or triangular shape.
9. The compressor of claim 1, wherein said partition plate is detachable.
10. The compressor of claim 1, further comprising a magnetic-conductive material disposed between said permanent magnet arrays and the outer wall of said movable cylinder.
11. A linear compressor with permanent magnets, comprising:
- a first movable cylinder having at least one first permanent magnet arrays and a first partition plate, said first movable cylinder having one opening respectively formed at each of two ends thereof, said partition plate disposed in said first movable cylinder to separate said first movable cylinder into a first sub-cylinder and a second sub-cylinder, said first permanent magnet array disposed at an outer wall of said first movable cylinder in an axial direction thereof and having a plurality of permanent magnets in which adjacent magnets are magnetized oppositely;
- a second movable cylinder having at least one second permanent magnet arrays and a second partition plate, said second movable cylinder having one opening respectively formed at each of two ends thereof, said second partition plate disposed in said second movable cylinder to separate said second movable cylinder to a third sub-cylinder and a fourth sub-cylinder, said second permanent magnet arrays disposed at an outer wall of said second movable cylinder along an axial direction thereof and having a plurality of permanent magnets in which adjacent magnets are magnetized oppositely;
- at least a first stationary electromagnetic winding set disposed outside said first movable cylinder relative to said first permanent magnet array, said first stationary electromagnetic winding set including a plurality of lateral branches and a plurality of sub-winding sets, wherein said sub-winding sets are wound in a way that said first stationary electromagnetic winding set generates alternative positive and negative magnetic fields to attract or repel said first movable cylinder to move along the axial direction when an alternate current is applied to said first stationary electromagnetic winding set;
- at least a second stationary electromagnetic winding set disposed outside said second movable cylinder relative to said permanent magnet array, said second stationary electromagnetic winding set including a plurality of lateral branches and a plurality of sub-winding sets, wherein said sub-winding sets are wound in a way that said second stationary electromagnetic winding set generates alternate positive and negative magnetic fields to attract or repel said second movable cylinder to move along the axial direction when a alternate current is applied into said second stationary electromagnetic winding set;
- a first stationary piston having a first main chamber with a front end thereof placed in the opening of one said end of said first movable cylinder and a rear end thereof becoming open, said first main chamber including a plurality of first sub-chambers with a front end thereof provided with at least two check valves having different flow directions respectively corresponding to one of said first sub-chambers;
- a second stationary piston having a second main chamber with a front end thereof placed in the opening of one said end of said second movable cylinder and a rear end thereof becoming open, said second main chamber including a plurality of second sub-chambers with a front end thereof provided with at least two check valves having different flow directions respectively corresponding to one of said second sub-chambers; and
- a third stationary piston having a third main chamber, said third main chamber having two third sub-chambers, an outlet passage and an inlet passage, a front end of said third main chamber placed in the opening of the other end of said first movable cylinder and a rear end thereof placed in the opening of the other end of said second movable cylinder, the front and rear ends of said third main chamber respectively provided with two check valves with different flow directions corresponding to said third sub-chambers, said outlet passage formed at one side of one of said third sub-chambers, and said inlet passage formed at one side of the other one of said third sub-chambers;
- wherein said first movable cylinder and said second movable cylinder move forward or backward along the axial direction in response to a phase of the current applied to said first stationary electromagnetic winding set and said second stationary electromagnetic winding set.
12. The compressor of claim 11, further comprising an outer shell for accommodating said first movable cylinder, said second movable cylinder, said first stationary electromagnetic winding set, said second stationary electromagnetic winding set, said first stationary piston, said second stationary piston and said third stationary piston, wherein said first and second movable cylinders and said first, second and third stationary pistons are disposed along an axial direction of said outer shell, said first and second stationary electromagnetic winding sets are disposed at an inner wall of said outer shell.
13. The compressor of claim 12, further comprising at least a pair of sliding rails disposed at two opposite positions of the inner wall of said outer shell along the axial direction thereof for guiding the movement of said first and second movable cylinders.
14. The compressor of claim 11, wherein said first, second and third stationary pistons guide the movement of said first, second and third movable cylinders.
15. The compressor of claim 11, wherein a plurality of first permanent magnet arrays and a plurality of second permanent magnet arrays respectively and symmetrically disposed at an outer wall of said first movable cylinder and said second movable cylinder, and a plurality of said first stationary electromagnetic winding sets and a plurality of said second stationary electromagnetic winding sets are respectively disposed outside said first movable cylinder and said second movable cylinder corresponding to said first permanent magnet arrays and said second permanent magnet arrays.
16. The compressor of claim 15, wherein said first permanent magnet arrays and said second permanent magnet arrays are respectively disposed at the outer walls of said first movable cylinder and said second movable cylinder in a geometric arrangement of cross shape, X shape or triangular shape.
17. The compressor of claim 11, wherein said first partition plate and said second partition plate are detachable.
18. The compressor of claim 11, further comprising a first magnetic-conductive material disposed between said first permanent magnet array and the outer wall of said first movable cylinder and a second magnetic-conductive material disposed between said second permanent magnet array and the outer wall of said second movable cylinder.
19. A two stage linear compressor with permanent magnets comprising:
- a movable cylinder having at least one permanent magnet array and a partition plate, said movable cylinder having one opening formed at each of two ends thereof, said partition plate having at least one interstage check valve and disposed in said movable cylinder to separate said movable cylinder into a first sub-cylinder and a second sub-cylinder, said permanent magnet array disposed at an outer wall of said movable cylinder in an axial direction thereof and including a plurality of permanent magnets in which adjacent magnets are magnetized oppositely;
- at least one stationary electromagnetic winding set disposed at outside of said movable cylinder relative to said permanent magnet array, said stationary electromagnetic winding set including a plurality of lateral branches and a plurality of sub-winding sets, wherein said sub-winding sets are wound in a way that said stationary electromagnetic winding set generates alternate magnetic fields to attract or repel said movable cylinder to move along the axial direction when an alternate current is applied to said stationary electromagnetic winding set;
- a first stationary pistons, said first stationary pistons having a main chamber with a front end thereof placed in the opening of said first sub-cylinder and a rear end of said main chamber becoming open, said main chamber having at least one intake check valve disposed at said front end thereof; and
- a second stationary pistons, said second stationary pistons having a main chamber with a front end thereof placed in the opening of said second sub-cylinder and a rear end of said main chamber becoming open, said main chamber having at least one discharge check valve disposed at said front end thereof;
- wherein said movable cylinder moves forward or backward along the axial direction in response to a phase of the current applied to said stationary electromagnetic winding set, and accordingly changing volumes of said first sub-cylinder and said second sub-cylinder, a working fluid is drawn into said first sub-cylinder through said intake valve and is compressed and transferred through said interstage valve into the said second sub-cylinder piston in a first stage of compression, and further is compressed and transferred out of said second sub-cylinder through said discharge valve, in a second stage of compression.
20. The compressor of claim 19, further comprising an outer shell for accommodating said movable cylinder, said stationary electromagnetic winding set and the said first and second stationary pistons, wherein said movable cylinder and the said stationary pistons are disposed in a way along an axial direction of said outer shell, and said stationary electromagnetic winding set is disposed at an inner sidewall of said outer shell.
21. The compressor of claim 20, further comprising at least a pair of sliding rails respectively disposed at two opposite positions of one inner wall of said outer shell along the axial direction thereof for guiding the movement of said movable cylinder.
22. The compressor of claim 19, wherein the said first and second stationary pistons guides the movement of said movable cylinder.
23. The compressor of claim 19, wherein said movable cylinder has a plurality of said permanent magnet arrays symmetrically disposed at the outer wall of said movable cylinder, and a plurality of said stationary electromagnetic winding sets are disposed at outside of said movable cylinder respectively corresponding to one of said permanent magnet arrays.
24. The compressor of claim 23, wherein said permanent magnet arrays are disposed at the outer wall of said movable cylinder in a geometric arrangement of cross shape, X shape or triangular shape.
25. The compressor of claim 19, further comprising a magnetic-conductive material disposed between said permanent magnet arrays and the outer wall of said movable cylinder.
26. The compressor of claim 19, wherein an outer diameter of said second stationary piston and an inner diameter of said second sub-cylinder are smaller than that of said first stationary piston and said first sub-cylinder, respectively.
Type: Application
Filed: Jul 2, 2008
Publication Date: Jun 11, 2009
Applicant:
Inventors: Te-Yang Shen (Hsinchu County), Chung-Chu Chen (Hsinchu)
Application Number: 12/216,358
International Classification: F04B 31/00 (20060101);