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Motor-mounted internal gear pump and electronic deviceRelated Patent Categories: Pumps, Motor Driven, Electric Or Magnetic Motor, Rotary Expansible Chamber Pump, Interengaging Rotary Pumping MembersMotor-mounted internal gear pump and electronic device description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20050265860, Motor-mounted internal gear pump and electronic device. Brief Patent Description - Full Patent Description - Patent Application Claims
CLAIM OF PRIORITY [0001] The present application claims priority from Japanese application serial JP 2004-155676 filed on May 26, 2004, the content of which is hereby incorporated by reference into this application. FIELD OF THE INVENTION [0002] The present invention relates to a motor-mounted internal gear pump and electronic device. BACKGROUND OF THE INVENTION [0003] An internal gear pump has conventionally been well-known as a pump for delivering conveyed liquid against a pressure. Particularly, it has been popular as a hydraulic pump or oil pump. [0004] An internal gear pump is composed, as main active components, of an internal rotor having teeth formed around the outer periphery and having a shape of a spur gear and an annular-shaped external rotor having teeth formed around the inner periphery and having a width generally same as that of the internal rotor. A casing having an inner flat face facing to both side faces of these rotors via a slight gap is provided so as to accommodate both rotors. The number of teeth of the internal rotor is generally less than the number of teeth of the external rotor by one. They rotate in the same way as a power transmission gear with both rotors meshed with each other. The liquid sealed in the tooth space is pumped and discharged by the change in the area of the tooth space with this rotation, thereby functioning as a pump. When one of internal and external rotors is driven, the other is rotated since they are meshed with each other. However, in most cases, a center shaft connected to the internal rotor is externally driven. The rotational centers of both rotors are shifted from each other, so that it is necessary to rotatably support each rotor. Formed at the flat inner face are at least one so-called suction port and one so-called discharge port that are opening sections to a flow channel communicating with the outside. The suction port is provided so as to oppose to the tooth space whose volume is increased, while the discharge port is provided so as to oppose to the tooth space whose volume is decreased. The popular tooth shape of the rotor is such that an arc is applied to a part of the tooth shape of the external rotor and a trochoid curve is applied to the tooth shape of the internal rotor. [0005] Japanese Patent Laid-Open No. H11(1999)-50971 (Patent Reference 1) discloses a conventional pump wherein an internal gear pump mechanism and a motor for driving the same are integrally formed. In this conventional pump, the internal gear pump mechanism are arranged in parallel at the side face of the motor, wherein the internal gear pump mechanism is driven by a driving shaft of the motor. [0006] [Patent Reference] [0007] Japanese Patent Laid-Open No. H11(1999)-50971 SUMMARY OF THE INVENTION [0008] The pump disclosed in the Patent Reference 1 has a problem that the entire size is increased, so that the pump is made large-sized, since the internal gear pump mechanism and the motor for driving the same are arranged in parallel in the shaft direction. Further, the driving shaft of the motor drives the internal gear pump mechanism, so that a shaft sealing device should be provided between the internal gear pump mechanism and the motor. Providing the shaft sealing device brings problems of increasing cost and deteriorating reliability due to its service life and leakage of a conveyed liquid. In case where the pump is used for an electronic device, in particular, it is important to prevent the leakage of the conveyed liquid, since a small amount of leakage may possibly entail a breakdown of the entire electronic device. [0009] An object of the present invention is to provide a motor-mounted internal gear pump that is small-sized and less expensive and has high reliability, while utilizing a function of an internal gear pump that is suitable for high head, and an electronic device. [0010] In order to attain the aforesaid object, the present invention provides a motor-mounted internal gear pump provided with a pump section for sucking and discharging a liquid and a motor section for driving the pump section, wherein the pump section comprises an internal rotor having teeth formed around the outer periphery; an external rotor having teeth, that are meshed with the teeth of the internal rotor, formed around the inner periphery; and a pump casing that accommodates both rotors and has a suction port for sucking a liquid and a discharge port for discharging a liquid, and the motor section comprises a can that composes a part of the pump casing and formed of a non-magnetic material into a thin plate; a rotator arranged at the inside of the can for driving the external rotor or the internal rotor; and a stator arranged at the outside of the can for rotating the rotator. [0011] Specific preferable structures of the present invention are as follows. [0012] (1) The rotator is made into a cylindrical shape and is fixedly disposed to the outer periphery of the external rotor so as to surround the outer periphery of the external rotor, the can is made into a thin cylindrical shape and surrounds the outer periphery of the rotator, and the stator is made into a cylindrical shape and arranged at the outside of the can. [0013] (2) In the pump casing, the internal rotor is rotatably supported about a shaft that is fitted into its central hole, and the external rotor is fitted into an inner peripheral face of a bracket section that projects in the shaft direction. [0014] (3) The bracket section is formed so as to project from both sides in the shaft direction, and the shoulder section of the pump casing arranged at both sides of the external rotor is fitted into the inner peripheral face of the bracket section projecting at both sides, whereby the external rotor is rotatably supported by the pump casing. [0015] (4) The motor section is composed of a DC brushless motor whose rotator is made of a permanent magnet, and magnetism detecting means having a function of detecting the passage of the permanent magnet is provided at the outside of the can, wherein a current control device is provided for controlling the current supplied to the stator of the DC brushless motor based upon the output of the magnetism detecting means. [0016] (5) The internal rotor and the external rotor are injection-molded from a synthetic resin material having a self-lubricating property, and the directions of drafts with this injection molding are reverse to each other in the state where both rotors are meshed with each other, wherein both rotors are meshed with each other such that the diameter of the internal tooth of the external rotor is increased in the direction in which the diameter of the external tooth of the internal rotor is increased. [0017] (6) The space where the internal rotor and the external rotor are accommodated is isolated from the outside by the casing including the can, except for the flow channel passing through the suction port and the discharge port, wherein a flow channel is provided through which at least a part of the liquid in the suction or discharge paths flows via the inner space of the can. [0018] (7) The current control device is thermally brought in close contact with the casing. [0019] (8) A motor driving circuit provided with power consumption detecting means is incorporated, and a control function is provided, this control function performing an operation with a speed more increased than a normal rotational speed by a limited period in case where it is determined that the electric power consumption immediately after the activation is smaller than a predetermined value, and that changes the increased speed to the normal rotational speed in case where it is determined that the electric power consumption exceeds the predetermined value. [0020] (9) THE motor-mounted internal gear pump according to claim 1, wherein the can is made of a non-magnetic member such as stainless steel or resin. Continue reading about Motor-mounted internal gear pump and electronic device... Full patent description for Motor-mounted internal gear pump and electronic device Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Motor-mounted internal gear pump and electronic device patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Motor-mounted internal gear pump and electronic device or other areas of interest. ### Previous Patent Application: Fluid supply unit, in particular hydraulic supply unit Next Patent Application: Diaphragm pump Industry Class: Pumps ### FreshPatents.com Support Thank you for viewing the Motor-mounted internal gear pump and electronic device patent info. 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