Abstract:
An air pump for an aquarium includes a power source, first and second electromagnetic coils, and a circuit powered by the power source and coupled to the coils for energizing the coils in an alternating manner at a selected frequency, the circuit including an arrangement for varying the selected frequency. The air pump also includes a mechanical pump mechanism having two magnets which are each movably supported near a respective one of the coils and move in response to energization of the coils, and a pump arrangement which is responsive to movement of the magnets for effecting flow of a fluid.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an air pump for an aquarium, and more particularly, to an improved air pump which is used for an ornamental aquarium and does not make noise during operation, meaning the air pump can generate bubbles without making noise. 
     The air pump according to the present invention has a rectifying diode and smoothing condenser connected to a power source part in order to transmit electric power to the oscillation part and the amplification part by means of converting standard electric alternating current power into direct current, and a variable resistance is connected to the oscillation part of an instable multi-vibrator circuit in order to vary the polarity of the electromagnetic coil for controlling the driving frequency from 10 Hz to 30 Hz optionally and then to widen the vibration of a vibrating lever for the purpose of minimizing noisy sounds and preventing a decrease of the quantity of air. 
     Two resistances and two transistors are connected within the amplification part in order to induct electric current to the electromagnetic coil for the purpose of forming bipolar fields. 
     In the present invention, according to the above described formation, the efficiency of air pumping can be raised, the inventive device can be formed simply and can be set into a relatively small container, and the life of the inventive device can be extremely long by virture of the simple formation and by preventing decrease of the stroke of the air pump. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The drawing shows the circuit of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawing, the FIGURE is a circuit diagram of the invention and therefore, will be described only briefly herein. 
     The power source part 1 is formed to convert AC electric power of 120 volts into direct current-electric power by the rectification diode D 1  and the smoothing condenser C, and the electric power is transmitted to the electromagnetic coils L 1  and L 2  of the amplification part 3 by means of electric current controlling resistance R 8  which is connected to the plus wire of the DC electric power source, and the constant voltage diode ZD is connected with the electric current controlling resistance R 7  so that a fixed low voltage (from 6 V to 12 V) can be formed, thereby allowing electric power to be supplied to the oscillation part 2. 
     The oscillation part 2 includes resistances R 1  R 2 , R 3  and R 4 , condensers C 1  and C 2  and transistors T 1  and T 2  forming a instable multi-vibrator connected with the said power source 1. A volume varying resistance VR is located between said resistances R 3  and R 4  and the plus wire so as to be connected with said resistances R 3  and R 4  and said plus wire, current controlling resistances R 9  and R 10  are connected to the bases of transistors T 3  and T 4  of said oscillation part 3 respectively and said resistances R 9  and R 10  are also respectively connected with the collectors of said transistors T 1  and T 2  of said oscillation part 2, the collectors of said transistors T 3  and T 4  are respectively connected with respective ends of said electromagnetic coils L 1  and L 2 , protective reverse blocking diodes D 4  and D 5  are connected to respective ends of said electromagnetic coils L.sub. 1 and L 2 , and each emitter of said transistors T 3  and T 4  are connected together. 
     Of numerals, 4 is a vibrating lever, 5 is a rubber pump, 6 is a permanent magnet, 7 is an air pump body and 8 is an air pipe. 
     In the present invention as hereinbefore mentioned, the power source 1 converts 120 electric power into direct current-electric power by means of the rectification diode D 1  and smoothing condenser C and, at the same time, supplies driving electric power to the electromagnetic coils L 1  and L 2  of the amplification part 3 through the electric current controlling resistance R 8 , and fixed low volts (from 6 to 12 voltage) can be formed by the electric current controlling resistance R 7  and the constant voltage diode ZD to supply electric power to the oscillation part. 
     The oscillation part 2 includes the instable multi-vibrator circuit with the frequency controlling variable resistance VR. When a high electric potential of DC electric power is applied to the bases of the transistors T 1  and T 2  through said variable resistances VR and said resistances R 3 , a R 4  and voltage is charged to the condenser C 1  through the resistance R 1  and the resistance R 3  when the transistor T 1  becomes ON and then a reverse voltage is applied to the base of the transistor T 2  so that said transistor T 2  becomes OFF. After a certain time has elapsed, the voltage is applied to the base of the transistor T 2  as a forward direction voltage because the voltage of the condenser C 1  becomes zero and then the transistor T 2  becomes ON so that the condenser C 2  can be charged by the resistance R 2  and the resistance R 4  thereby allowing the transistor T 1  to become OFF. 
     Furthermore, after a certain time elapsed, the electric potential of the condenser C 2  becomes zero and the cycle repeats. Consequently, a pulse train is generated because of repeating of the ON and OFF states of the transistor T 2 . 
     The charging and discharging times can be varied from 10 to 30 Hz since the period of the pulse train is controlled by the volume varying resistance VR. 
     Further, in the amplification part 3, if the emitter and the collector of transistor T 2  of the said amplification part 3 are electrically connected with each other due to the transistor T 2  being ON, the emitter and the collector of the transistor T 1  are disconnected with each other, and then, electric power is applied to the base of the transistor T 4  of the amplification part through the resistance R 1  and electric power is inducted to the electromagnetic coil L 2  so that the permanent magnet 6 of the vibrating lever 4 moves because it is repulsed by the electromagnetic field. 
     At this time, electric power is not applied to the base of the transistor T 3  of the amplification part since the emitter and the collector of the transistor T 2  have been electrically connected with each other so that the emitter and the collector of the transistor T 3  are disconnected with each other and then electric current is not transmitted to the electromagnetic coil L 1 , thereby generating no electromagnetic field. 
     Furthermore, the transistor T 2  is disenergized and the transistor T 1  is energized when a certain time has elapsed at the predetermined frequency, and electric power is applied to the base of the transistor T 3  through the resistance R 2  so that electric current is inducted to the electromagetic coil L 1  by conduction of the emitter and collector of the transistor T 3  and then the permanent magnet 6 of vibrating lever 4 moves in a direction producing suction and, simultaneously, the rubber pump 5 connected with said vibrating lever 4 does the action of reciprocal vibration and effects air movement. 
     As hereinbefore mentioned, in the invention, AC electric power can be converted into DC electric power by said rectification diode D 1  and said smoothing condenser C, and low voltages (from 6 V to 12 V) can be formed by said electric current controlling resistance R 7  and said constant voltage diode, and a transformer is not required in the oscillation part and, therefore, the invention can be contained in a small size of container. 
     The variable resistance VR is connected between the resistances R 3 , R 4  of the oscillation part 2 and the plus wire of the electric power source in order to optionally control the frequency into low period, and therefore, the invention does not make noise during operation so that the invention can be used in a house even in the night. 
     The rubber pump 5 has wide vibration stroke but is subjected to a small number of vibrations per unit time, and thus, the life of the air pump according to the invention lasts long. 
     Further, in the invention, resistances R 9  and R 10 , transistors T 3  and T 4  and diodes D 4  and D 5  are connected within the amplification part 3 so that transistor T 3  and transistor T 4  do alternating operation and then electromagnetic coils L 1  and L 2  do alternating electric current induction forming bipolar fields, whereby the repulsion of each permanent magnet 6 and the subsequent movement of that permanent magnet 6 for suction can be performed effectively so that air flow can be generated effectively by effective actions of said rubber pump 5. 
     The invention can be used for a conventional aquarium and the like.