Nitto Kohki Co., Ltd.

Kawasaki Steel Corporation

Man Design Co., Ltd.

Toshio Osada

Masaaki Tanabe

Toshio Mikiya

Tamotsu Mori

Yutaka Tanaka

Kenji Mizuno

Akira Kawamura

Toshikazu Masuda

Shinji Gotoh

A coating fault locating technique transmits a base electric signal from a power source to a buried metal pipe. A location of a coating fault in the buried pipe is detected by detecting a gradient of a changing magnetic field between two points spaced along the buried pipe. The gradient is detected based upon the output differential of at least one pair of search coils. The gradient is caused by a leakage of current that occurs at the coating fault. In particular, the at least one pair of search coils are provided in a mobile unit that is located above ground. The at least one pair of search coils are spaced apart from one another and have their axes arranged so as to have a low sensitivity to a magnetic field generated by the base electric signal running through the buried pipe. The at least one pair of coils are spaced apart from each other such that a line drawn between midpoints of the search coils' axes crosses a plane normal to the axis of the buried pipe. For example, the at least one pair of search coils are spaced from each other horizontally, with each coil arranged with its axis extending in a vertical plane. The data detected by the search coils in the mobile unit can be transmitted to a GPS system, which then generates a map identifying the locations of any detected coating faults.

Method and apparatus for locating coating faults on buried pipelines

The inside-outside positional relationship between a field core of an electromagnet and an armature provided on a piston in an electromagnetic pump is reversed as compared with the prior art pump, that is, an annular armature is placed outside and a field core is placed inside the armature. The annular armature attached to the piston reciprocates in the axial direction thereof and the inside surface of the armature is opposed to the outside circumference of the field core of an electromagnet having formed thereon a plurality of outwardly and radially projecting magnetic poles, and being fixed to a part of a casing.

Electromagnetic pump

An electromagnetic reciprocating pump comprising of a closed-type casing provided with a cylinder in front thereof, a main shaft as least the front end of which is fixed to the casing, a piston having a piston head in front thereof, which piston is slidably fitted over the outer periphery of the main shaft to reciprocate, and coaxially supporting an armature, a spring disposed between the piston and the casing for biasing the piston in one direction, an electromagnet fixed to the casing so as to attract the armature in the opposite direction against the biasing force of the spring, suction ports and suction valves for sucking a fluid into a pressure chamber defined by the cylinder and the piston head, and a discharge port and a discharge valve for discharging the pressurized fluid from the pressure chamber.

Electromagnetic reciprocating pump

An electromagnetic reciprocating pump which maintains the outlet pressure at a preset value comprising a pressure sensor for detecting the actual outlet pressure of the electromagnetic reciprocating pump and means to feedback control the frequency of the reciprocating motion and, if necessary, its stroke of the electromagnetic drive means based on the deviation from the preset outlet pressure of the actual outlet pressure. The reciprocating motion frequency control of the electromagnetic drive means may be done by modulating the frequency and amplitude of the half-wave AC current supplied to the electromagnetic drive means. With this, the control of the number of times of the reciprocating motion of the electromagnetic drive means can be carried out without changing the reciprocating motion stroke of the electromagnetic drive means.

Outlet pressure control system for electromagnetic reciprocating pump

An electromagnetic reciprocating pump having a piston electromagnetically moved at least in one direction is comprised of a frame having attached thereto an electromagnet which operates the piston, an inner cylinder whose one end side in the axial direction is secured to the frame and the other side thereof is closed and having the piston accommodated therein such that the piston can be reciprocated therein, an outer cylinder whose one end in the axial direction being secured to the frame and coaxially encircling the inner cylinder so as to form a working chamber between it and the inner cylinder, an outer piston accommodated within the working chamber so as to freely reciprocate and varying a capacity of working chamber, spring means being contracted and expanded in accordance with the movement of the outer piston, and magnetic coupling means for magnetically coupling the inner piston and the outer piston. The piston has a shape such that this piston does not form a pressure in the inner cylinder when reciprocated within the first cylinder. Further, the outer cylinder has a suction opening and a discharge opening, each having a valve, for sucking and discharging a special fluid, such as corrosive liquid, into and from the working chamber.

A solenoid-operated reciprocating pump includes a casing having a cylinder with a central axis. A main shaft is disposed in and secured at one end to the casing in alignment with the central axis of the cylinder. A piston having a piston head is slidably fitted over the main shaft such that the piston head is disposed within the cylinder for axial motion. A coil spring extends between the piston and casing to bias the piston in a first axial direction and an armature radially extends from the outer periphery of the piston for interaction with an electromagnet disposed around the longitudinal periphery of the piston. The electromagnet attracts the armature and hence the piston in a second axial direction opposite from the first direction. On end of the coil spring is fixed to one of the piston or the casing and the other end of the spring is rotatably supported on the other of the piston or the casing by a spring retainer seated on a plurality of spherical balls which are in turn seated on said other of the piston or the casing means. The balls are positioned at equal distances radially from the central axis of the coil spring and at equal circumferential spacings around the axis.

Solenoid-operated reciprocating pump

An electromagnetic pump comprising fluid operation chambers for discharging fluid to the outside; and electromagnet connected to an AC power source device for polarity switching for every half cycle of AC when energized; a permanent magent which moves together with the electromagnets; and a reciprocative shaft holding the permanent magnet, which reciprocates in the shaft direction when the electromagnet is energized. The width of a securement portion for the permanent magnet of the reciprocative shaft is relatively narrow compared to the other portions, and the permanent magnet consists of a pair of permanent magnet pieces bonded together by sandwiching the securement portion therebetween. The electromagnetic pump further comprises a fluid operation member for expanding or contracting the volume in the fluid operation chamber by the reciprocation movement of the reciprocative shaft so as to guide fluid out.

Growing community of inventors

Tokyo, Japan

Toshio Osada