Patent Application
20070212237
This application claims the benefit of Chinese Patent Application No. 200410051345.6 filed which is explicitly incorporated by reference in its entity.
This invention relates to a piston pump, and more particularly to a magnetically suspended piston pump.
In the prior art, a piston pump typically comprises a cylinder, a piston, an inlet valve and an outlet valve located in the cylinder, and a driving mechanism connected to the piston. The driving mechanism usually comprises a crank connecting rod, a vapor device, and a magnetic connecting rod driving device, etc. According to the number of the cylinders or the number of the inlet/outlet valves, the piston pump may be classified as a single-cylinder, a double-cylinder and a triple-cylinder piston pump, or as a single-purpose and a double-purpose piston pump.
The conventional piston pump has disadvantages that it is of a relatively short service life and includes some easily worn-out parts, for a contact between a piston and a pump will lead to abrasion. Particularly, if the pump is kept continuously working for a long time (e.g., 24 hours a day), some parts of the piston pump should be replaced within 2 years. Even the pump made from the best abrasion-resistance materials will be worn or penetrated (diaphragm pump) in the end. Moreover, resistance generated due to the friction or tension between the portions of the pump (especially working at a high speed) gives rise to a low power efficiency of the pump. That is, power exchanging efficiency of the pump is reduced.
It is an object of the present invention to provide a magnetically suspended piston pump having a new configuration, in which a piston of a cylinder is able to work at a magnetically suspended situation without friction, thereby enhancing the power efficiency and the reliability of the pump.
To accomplish the object of the present invention, a magnetically suspended piston pump is provided, comprising a cylinder, a piston, an inlet valve and an outlet valve located in the cylinder, and a driving mechanism connected to the piston, in which the cylinder is made of permanent magnet, and the piston embedded within the cylinder is also made of permanent magnet. In the invention, the magnetic polarity of an outer surface of the piston is the same as that of an inner surface of the cylinder, and a circular magnetic plate is provided at an end of the cylinder, in which a side surface of the circular magnetic plate towards an inside portion of the cylinder has the same magnetic polarity as a surface of the piston facing to the magnetic plate.
According to an embodiment of the present invention, the circular magnetic plate disposed within the cylinder is made of permanent magnet or electromagnet.
According to another embodiment of the present invention, the piston pump comprises a magnetic connecting rod driving device. The cylinder of this embodiment is configured in a double-cylinder structure, which comprises an upper cylinder and a lower cylinder. A magnetically suspended piston located in the upper cylinder is connected to another magnetically suspended piston located in the lower cylinder by a vertical connecting rod. Two circular permanent magnets are provided at the connecting rob, and a pair of electromagnets are provided at two sides of the circular permanent magnets. A group of coils is disposed in each of the electromagnets. The two groups of coils are connected with each other in series.
In the present invention, two electromagnets, which are controlled by an electronic circuit, may be provided at both ends of the inside of the cylinder, respectively. The electronic circuit may comprise a common-mode rejection circuit, a microprocessor control circuit, and a power amplification circuit. A signal generated by the electromagnets for indicating a variation of the magnetic field is transmitted to the microprocessor control circuit through the common-mode rejection circuit. The microprocessor control circuit generates a response to the signal for driving the power amplification circuit, and then an output signal of the power amplification circuit is transmitted to the electromagnets.
Compared with the prior art, the present invention has the following advantages:
1. The piston fit within the cylinder of the invention works at a magnetically suspended situation without friction between the piston and the cylinder, which thereby renders the piston pump of a higher efficiency and lower power consumption. The power consumption of the invention is generally about half that of a conventional piston pump.
2. The piston pump of the present invention is durable and reliable and in no need of replacement of any parts. Moreover, the piston pump of the invention shows more advantageous when it is employed in an apparatus which needs to work continuously, such as a medical device.
The present invention and various advantages thereof will be described with reference to exemplary embodiments in conjunction with the drawings.
Refer to
The piston 2 of the pump is magnetically suspended within the cylinder 1, and fulfills compression or suction of the liquid/gas by moving up and down within the cylinder 1. In practice, the cylinder 1 can be a permanent magnet which generates a uniform magnetic field at an inner surface 100 of the cylinder 1. That is, the intensity of the magnetic field is identical at each of 360 degrees to the inner surface 100. The piston 2 is a circular permanent magnet, and a magnetic polarity of an outer surface 200 of the piston 2 is the same as that of the inner surface 100 of the cylinder 1. For example, each of them is of an N-pole, and therefore between the outer surface 200 and the inner surface 100 a repulsive force will be generated. The repulsive force is identical at each of 360 degrees to the inner surface 100 due to the uniform magnetic field, so that the outer surface 200 of the piston 2 will never contact the inner surface 100. In this manner, the piston 2 is able to avoid contacting the cylinder 1 when moving within the cylinder 1. The principle of the embodiment is to ensure the intensity of the magnetic field to be identical at each of 360 degrees. In the practical operation, such a magnetic field can be easily realized by choosing a proper direction of magnetization. Moreover, there is no need to keep the magnetic field in the upper position equal to the lower position of the inner surface 100. Therefore, it is possible to ensure the piston 2 to be suspended within the cylinder 1 and to move only in an up and down direction. A movement of the piston 2 can be limited to a certain range to further restrict a working travel distance thereof by setting another magnetic field at an opening of the cylinder, which provides the same magnetic polarity as a surface of the piston 2 facing thereto.
According to an embodiment of the present invention, as shown in
According to another embodiment of the present invention, an alternating magnetic field is applied to both ends of the cylinder to actuate the piston to move up and down to apply work. That is, the piston made of permanent magnet can be moved up and down by a magnetic attractive and repulsive force through alternating the magnetic field.
According to a further embodiment of the present invention, a fixed magnetic field is provided for controlling the movement of the piston. As shown in
Based on the above description, it is understood that no mechanical friction is generated by the piston pump of the present invention, since there is no mechanical contact during operation, which prevents the parts of the pump from being worn-out theoretically and makes the service life quite long. In the manufacturing, it is possible to ensure a high pressure (small instantaneous leakage) generated during operation, if only an outer diameter of the magnetically suspended piston matches an inner diameter of the magnetic cylinder. And, the pressure of applying work is constant when the cylinder is kept unchanged. When abrasion occurs due to some problems, a gap between the piston and the cylinder is increased, and thereby a relative pressure will be decreased. Therefore, it is very important to design a proper gap and a proper pressure for the piston pump with a small gap and an excellent precision also means a high cost and vice versa (The pressure, i.e., the power is mainly determined by an outside actuated force, however. For the same power, the sealing performance may be a key factor to determine the working pressure). The connecting rod 8 outside the cylinder is able to move up and down, thereby providing an actuated force, through magnetic fields generated by two circular permanent magnets 9 and 10. Two electromagnets 11 and 12 are respectively provided at two sides of the permanent magnets 9 and 10; forming an angle of 180 degrees from each other. A group of coils 13 are embedded within the electromagnet 11 and a group of coils 14 are embedded within the electromagnet 12. The two group of coils 13 and 14 are connected with each other in series (that is, when providing with electric power, the electromagnets placed with an angle of 180 degrees will generate an identical polarity). In this manner, when supplied with AC power, the magnets will move up and down with high efficiency due to the balanced force. Moreover, the magnets are able to avoid over-pumping due to the limitation of the configuration of the electromagnets. Consequently, the entire magnets are in a magnetically suspended situation without contacting any supporting parts, i.e., without causing mechanical friction. The invention can really provide a magnetically suspended piston pump.
Referring to FIGS. 3 to 4, according to another embodiment of the present invention, the pump just has one cylinder 1005, which has a configuration similar to the cylinder 1 as described above, except that the magnets disposed at both ends of the circular cylinder are not permanent magnets but electromagnets 15 and 16. In this embodiment, the attractive and repulsive force can be altered by varying a current direction of the electromagnets 15 and 16. However, this configuration is somewhat complicated for it is controlled by an electronic circuit. Two magnetic sensors are provided at both ends of the cylinder 1005 to monitor a position of the piston 205, so as to control a direction of the current. In practice, electromagnets 15 and 16 are able to serve as the sensors (referring to
The working principle of the above-mentioned pump is described as follows: When power is applied, a microprocessor circuit 18 generates an oscillating signal. Since, at the first period, it is not known what the initial position of the suspended piston 205 is, the suspended piston 205 is driven to move up or down. When the suspended piston 205 moves close to an end of the cylinder 1005, the magnetic field near the end is changed, which causes the sensors located near the end generating a signal. The signal is received by the microprocessor control circuit 18 through a common-mode rejection circuit 17, and the microprocessor control circuit 18 then generates a response command to indicate a power amplification circuit 19 to reverse the current direction. Therefore, the magnetic field is reversed, and the pump is turned to a compression situation from a suction situation and vice versa. In this way, the magnetically suspended piston 205 can be driven to move up and down to apply work. Since the electromagnets 15 and 16 respectively located at two ends of the cylinder 1005 are of opposite magnetic polarity (i.e., one is employed for generating an attractive force while the other one is employed for generating a repulsive force, but the magnetic polarity is switched as soon as the current direction is reversed). Thus, the operation provides a high efficiency and an excellent precision, and the working pressure or the suction force is constant, for it is the volume of applying work not the time that determines when to reverse the current direction. The volume of compression/suction work is identical for full-load and empty-load cases. Without being affected by friction, the compression/suction force of the piston pump is constant, which is especially useful for some cases requiring high precision (such as in the medical field). The piston pump of the present invention is easy to operate with a simply configuration, high efficiency, constant pressure, and excellent precision.
Moreover, the magnetically suspended piston pump of the present invention can be employed in various fields, such as in air pump or fluid field, for it is completely oil-free and rubber-free without causing abrasion of the components thereof. For example, the piston pump of the present invention is suitable to be used in some cases of corrosive gas, for the permanent magnet is durable against chemicals. If the piston pump is used in the case of corrosive fluid, the permanent magnet can be protected against the corrosion by coating with a corrosion proof material, such as a nylon coating. In practice, various materials may be used to manufacture the pump of the invention according to operational situations.
| Number | Date | Country | Kind |
|---|---|---|---|
| 200410051345.6 | Sep 2004 | CN | national |
