Abstract: Magnetic field producers are disposed either at the leading portion of an underground excavator or at a reference position in front of the underground excavator. The magnetic field producers can be constituted by a plurality of rectangular loops disposed to run parallel to one another and to overlap one another. The rectangular loops can be individually excited sequentially or they can be simultaneously excited at different frequencies. The magnetic field produced by a magnetic field producer can be detected by a first magnetic field detector and by a second magnetic field detector disposed to the rear of the first magnetic field detector so that the inclination angle of the underground excavator can be obtained from the difference between the positions of the two detectors. A loop of a magnetic field producing cable can be covered by a non-magnetic metal member so that wear and disconnection are prevented.

Abstract: A method and an apparatus for performing measurement by a resistivity method in order to detect the thickness of a sludge layer on the outer periphery of a shield machine. A Wenner electrode row (14) on the outer periphery of the machine is used to measure reference resistivities to thereby detect certain resistivities in the depth direction of the natural ground and the sludge layer thickness. At the same time, a dipole electrode row (16) is used to measure voltage distributions in the depth direction of the natural ground and in the direction of the arrangement of the electrodes. The ratios of the values measured by the measurement dipole electrodes to those measured by the reference Wenner electrodes are calculated, and their distribution is charted. When mutually equal values in the distribution map are connected together by continuous curves, a contour-pattern image is obtained, which enables a configuration of the collapse of natural ground to be determined.

Abstract: A continuous polymerization device is equipped with a stirring mechanism which possesses a drive shaft parallel to the direction of flow, a multiple number of polymerization precursor supply ports in the direction of flow, and at least one polymerization product output port at its latter portion, and possessing mixing capability with respect to the radial direction while possessing no actual mixing capability with respect to the direction of flow, in a continuous polymerization device which functions by piston flow.

Abstract: This invention relates to a device for removing short fibers from a mass of ibers. A pair of perforated cylindrical bodies are opposed to each other with a predetermined spacing defined therebetween, and static electricity is applied across the perforated cylindrical bodies. A suction-wise removing device is installed in at least one of the perforated cylindrical bodies. The initial end of a transfer conveyor is located on the surface of one perforated cylindrical body adjacent the opposed region. Short fibers contained in the mass of fibers fed to the opposed region by a feeding device are drawn into the suction-wise removing devices through the through holes in the cylindrical bodies by the action of electrostatic force and suction air currents. The mass of fibers having the short fibers removed therefrom are oriented by electrostatic force and transferred by the conveyor while being maintained in this oriented state.

Abstract: A vibration and acoustic wave detecting device employing a piezoelectric element has a construction such that a piezoelectric element comprises a first surface electrode disposed on a first surface of the piezoelectric element and having a first output terminal of the detecting device, a second surface electrode opposite to the first surface thereof, a side electrode disposed to surround a side surface of the detecting device and having portions respectively extending over the first and second surfaces, the three electrodes being disposed separately from each other, and a resistor disposed on the piezoelectric element to extend across the first surface electrode and the side electrode and to be connected therewith electrically, and the piezoelectric element further comprises a conductive member which is attached to the piezoelectric element to be in contact with the second surface electrode and the side electrode and hence to provide electrical connection between both electrodes.

Abstract: A vibration detecting apparatus comprises a housing having at one end thereof an opening, a piezoelectric element disposed within the housing, a connector mounted to the housing to cover the opening thereof and having an output pin, a lead wire for electrically connecting the piezoelectric element with the output pin, and an initially conical annular spring having an outer peripheral edge portion thereof received by an annular groove formed in an inner peripheral wall of the housing. The piezoelectric element is biased by the initially conical annular spring.

Abstract: In a feedback type ignition timing control system for internal combustion engines, the predetermined correction advance/retard angle values are stored in a read/write memory at the respective storage areas defined by the respective operating conditions of an engine, and the correction advance/retard angle values are each separately rewritten in accordance with the detected associated engine condition in response to a signal detecting the feedback factor. The advance/retard angle value for the ignition timing corresponding to the detected engine condition is separately determined in accordance with the corresponding rewritten advance/retard angle value and the ignition timing is controlled to suit the respective engine conditions in accordance with the correction advance/retard angle values preliminarily rewritten in response to the feedback factor.

Abstract: A knock detecting apparatus for an internal combustion engine includes a vibrating sheet branched into a plurality of vibrating reeds by forming a recess from one end of the vibrating sheet. The vibrating reeds have different lengths, shapes or thicknesses, and the other end of the vibrating sheet is fixed to a supporting member which is secured to the engine thereby to allow the vibrating reeds to vibrate with different resonance characteristics in response to the vibration of the engine caused by the knocking. The vibration of the vibrating sheet is detected, for example, as a change in reluctance by forming a magnetic path through the vibrating sheet and air gaps respectively located between the free ends of the vibrating reeds and a core.

Abstract: A knock detecting apparatus for detecting the occurrence of knocking in an internal combustion engine by detecting variations in the pressure of engine cooling water. A sealed double diaphragm structure is formed by a first diaphragm which is directly responsive to variations in the cooling water pressure and not resonant at the knock frequencies and a second diaphragm which is resonant at the knock frequencies. A noncompressible fluid is contained in the sealed double diaphragm structure between the two diaphragms. Pulsations of the second diaphragm, resonant at the knock frequencies, are detected by a magnetic device or a piezoelectric device operative to output an ac signal.

Abstract: A method of sensing a knocking taking place in an internal combustion engine through the sensing of pulsative component of the cooling water pressure or lubricating oil pressure. The sensing of the pulsative component is made by removing the static component from the composite pressure which is the sum of the pulsative component and the static component. An apparatus for sensing a knocking taking place in an internal combustion engine has a differential pressure sensing mechanism including a pressure sensing diaphragm and a pulsation absorption mechanism. The pressure sensing diaphragm receives at its one side the composite cooling water pressure or composite lubricating oil pressure which is the sum of the pulsative component and static component. The pulsation absorption mechanism absorbs the pulsative component from the composite pressure so as to transmit only the static component of the pressure to the other side of the pressure sensing diaphragm.

Abstract: A spark plug with a wide discharge gap includes an insulating layer formed on one or the other of its center and ground electrodes and disposed in the gap between the electrodes. The insulating layer includes an inner insulating layer of a material having a high dielectric constant and an outer insulating layer of a material having an excellent resistance to heat and high voltage, which surrounds the inner insulating layer, whereby ensuring a reduced discharge voltage, an improved ignition performance and improved heat resistance and durability.

Abstract: A spark plug includes a body of dielectric substance mounted on one of central and earth electrodes and having polarization effects. A gap for capacitive discharge is defined between the body of dielectric substance and the other of the electrodes, and a gap for inductive discharge is defined between the electrodes, which gap for inductive discharge is larger in dimension than the gap for capacitive discharge. With the arrangement, capacitive discharge to be produced in the early stage of discharge is caused at low discharge breakdown voltage due to polarization effects of the body of dielectric substance, and inductive discharge taking the main part of discharge for ignition is produced by utilizing the capacitive discharge of low voltage as trigger, thereby lowering discharge breakdown voltage to improve ignition performance of the spark plug.

Abstract: An ignition range detector for an internal combustion engine is disclosed, in which at each combustion of the internal combustion engine, a pressure signal of a pressure sensor for detecting the pressure in a cylinder is integrated by a signal associated with the crank angle to produce an area S.sub.1 +S.sub.2 presenting the combustion state. At the same time, the pressure signal for a hypothetical case of misfire under the same condition is integrated to produce an area S.sub.1. It is decided whether the ratio (S.sub.1 +S.sub.2)/S.sub.1 is higher than a predetermined value .alpha. or not thereby to detect an ignition range always stably regardless of the operating conditions of the internal combustion engine including the load thereon.

Abstract: A knocking sensing apparatus for sensing a knocking taking place in an internal combustion engine. The apparatus includes a diaphragm adapted to operate in response to the pressure of cooling water circulated in the engine, magnetism generating device, magnetic circuit including the diaphragm, and a magnetic flux detecting device adapted to detect in a manner like alternating current the change in the magnetic flux in the magnetic circuit caused by the operation of the diaphragm.

Abstract: A knock detecting apparatus includes a vibrating member with a disk-shaped vibrating portion whose resonant point is in the knock frequency range. The outer peripheral edge of the vibrating member is held substantially over the entire periphery. The vibrating portion of the vibrating member may be provided with holes and an addition such as a protrusion and/or a ring-shaped rib portion so as to vary the natural frequency of the vibrating member. Also, the size and shape of the holes and the cross-sectional area of the addition and/or the diameter of the rib portion may be varied to adjust the natural frequency of the vibrating member.

Abstract: An engine knock detecting apparatus having a vibration member with a plate-shaped vibratory portion having a resonance frequency in the frequency range of knocking of the engine. In order to adjust and optimize the degree of peak of the resonance, at least a part of the vibratory portion of the vibration member has a multi-layered structure consisting of two or more layers.

Abstract: The pressure in the cylinder Pi(-.THETA.A) at the fixed angle -.THETA.A preceding to maximum ignition advance at the time of each combustion is determined from the output signal of a pressure detector for detecting the pressure in the cylinder of the internal combustion engine. The pressure in the cylinder Pi(+.THETA.B) at a predetermined angle +.THETA.B during the expansion process is also determined. It is decided whether the ratio Pi(+.THETA.B)/Pi(-.THETA.A) is larger or smaller than a predetermined value .beta. thereby to detect an ignition range always regardless of the running conditions of the internal combustion engine.

Abstract: An ignition timing regulating device for use in an internal combustion engine for regulating the ignition timing of the engine depending on the pressure of ambient atmosphere. Based on the fact that the pressure in the intake manifold of the engine is equal to the pressure of ambient atmosphere in the starting stage of the engine, the output of a pressure sensor sensing the intake manifold pressure in the engine is applied to an atmospheric pressure sensing circuit so as to sense the value of atmospheric pressure in the engine starting stage, and the output of this atmospheric pressure sensing circuit is used for correcting the ignition timing of the engine.

Abstract: A knock detecting apparatus includes a vibrating means having a plate reed member adapted to vibrate in response to the vibrations of an internal combustion engine and a support member which is greater in thickness than the reed member and adapted to support the reed member, the reed and support members being made integrally from a magnetic material. When the reed member resonates upon the occurrence of knocking in the engine, the resulting change in the magnetic reluctance of the magnetic path including the reed member is sensed by a sensing coil to thereby detect the knock. The magnetic flux in the magnetic path is generated by a magnet or an excitation coil. An impedance element may be connected to the sensing coil or the excitation coil so as to correct variations in output from one coil to another.

Abstract: A magnetic path is formed by a vibrating member disposed in a housing in the radial direction and fixed at its end to the housing, a central magnetic path portion which is disposed to make a gap between the vibrating member and the central magnetic portion and to extend in the axial direction of the housing substantially at its center, a radial magnetic path portion extending from the central magnetic path portion in the radial direction of the housing with a predetermined spacing kept from the vibrating member, and an outer peripheral magnetic path portion extending from the outer peripheral side of the radial magnetic path portion toward the vibrating member. A permanent magnet for supplying magnetic flux to the magnetic path is disposed at the central magnetic path portion in the form of bar or at the outer peripheral magnetic path portion in the form of ring or to surround the central magnetic path portion.