An arc melting furnace apparatus is provided which reduces an operation burden on a worker and shortens working hours. An arc melting furnace apparatus 1 includes a housing 2 having formed therein a melting chamber 2a, a hearth 4 provided within the melting chamber 2a and having a recessed portion 4a, and a heating mechanism 10 for heating and melting a metal material supplied into the recessed portion 4 to generate an alloy ingot. The apparatus comprises a turning member 23 rotatably supported on a supporting member 21 standing within the melting chamber 2a, a perimeter edge of the turning member 23 rotating and moving along the inner surface of the recessed portion 4a to lift the alloy ingot generated in the recessed portion 4a above the hearth 4 and turn it over, and a resilient turn-over assisting member 24 provided above an upper end of the recessed portion 4a. Further, the turn-over assisting member 24 is arranged to flex by a predetermined amount when the alloy ingot abuts it, and to return to its original state from the flexed state so that the alloy ingot is urged to drop into the recessed portion 4a.

The invention relates to a safety device (1) for detecting electrode breakage in an electric arc furnace, wherein an electrode (6) is secured on an electrode support arm (4), and wherein a conduit is filled with a medium under a constant pressure and a pressure drop is produced at an electrode breakage, which is detected as an alarm signal. Here, the conduit (7a-d,3) is integrated in a protective component that is arranged beneath the electrode support arm (4) thereon, wherein in case of an electrode breakage, the conduit (7a-d,3) is damaged by a produce electric arc and the pressure drop takes place.

The invention relates to an electronic circuit and a method for feeding power to at least one electrode of an alternating-current electric-arc furnace, particularly for melting metal. Known circuits of this type typically comprise a series connection with a transformer for providing a supply voltage for the electric-arc furnace from a power grid (1) and a AC power controller (8) connected between the transformer (6) and the electrode (11) for regulating the current through the electrode (11). According to the invention, a further development for such electronic circuits is proposed, which development has a simple design, is inexpensive and prevents overload of the AC power controller (8) even in operating modes of the electric-arc furnaces at high electrode currents. This further development provides to bypass the AC power controller with a bypass switch (9) that is opened or closed with the help of a controller as a function of the amount of current flowing through the electrode (11).

A method, apparatus, and computer program product for generating a social network data structure, the method comprising: receiving a corpus comprising one or more communication indications for one or more customers, each communication indication indicating start time and end time of a communication of the customer; and generating a social network data structure indicating connections between customers based upon the start time and end time indications of communication indication comprised in the communication indications.

A high temperature industrial furnace roof system having first and second spaced apart hanger brick rows with a filler row disposed therebetween and a cable system including a plurality of electrical cables. The filler row includes a plurality of filler elements having at least one removable heating module with a heat source. The cable system operatively connects the heat source with a power source and permits the removable heating module to be removed from the respective filler element while the respective heat source remains operatively connected with the power source.

A sensor system for monitoring and controlling the performance of the bottom electrode and the deflection of an electric arc in an electric steel making furnace includes an organized matrix of anode pins interspersed with refractory material and extending toward an electrically conductive plate secured to distal ends of the anode pins. A sensing device includes two temperature sensors at spaced apart locations along each of a distributed select group of anode pins for providing corresponding electrical signals and a current sensor responsive to electrical current flowing through the anode pins of the distributed select group of anode pins for providing a corresponding electrical signal. A controller responsive to the electrical signals derived at the anode pins of the select group operates the power supply and a display for monitoring the electrical performance of the elongated anode pins for heating by the electric arc in the furnace.

An apparatus for dehydrating a liquid sample of biological material has a microwave waveguide that is open to the atmosphere. It has a microwave generator, means for introducing a container of the material into the waveguide, means for evacuating the container, means for rotating the container and means for removing the container from the waveguide. It can include means for moving the container through the waveguide and for sealing it. In a dehydration method, a container of the liquid sample is put into the open waveguide, evacuated, rotated at high speed and microwaved. The container of dehydrated material is then removed from the waveguide. The apparatus and method are particularly suitable for dehydrating vaccines.

An induction melting furnace having an asymmetrical sloping bottom. The melting furnace includes: an induction coil member provided on the melting furnace so as to melt waste contained in the furnace by vitrification; a bottom unit provided in a lower part of the melting furnace, the bottom unit asymmetrically sloping downward in a direction toward a glass discharge port that is formed through the bottom unit; and a cooling member integrated with the bottom unit. Due to the asymmetrical sloping bottom of the furnace, waste in the furnace can be completely melted and can be easily discharged to the outside and, accordingly, the time and cost required to treat the waste are reduced and this improves work efficiency when treating the waste. Further, due to the insulation material, the melting furnace can be protected from electric damage that may be caused by electric arc.

Metallurgical reactors having cooling capability and electrode feed capability are disclosed. The reactors may include a shell having a sidewall and a bottom, where the shell is adapted to contain a molten material. The reactors may include at least one consumable electrode protruding through an opening of the shell and into the molten material. The reactors may include a current contact clamp configured to conduct operating current to the electrode, where the current clamp is in contact with the electrode, and where the current clamp comprises at least one internal channel, wherein the internal channel is configured to circulate a cooling medium. The reactors may include an electric isolation ring disposed between the electrode and the opening of the shell, wherein the electric isolation ring is configured to sealingly engage the electrode and the opening so as to restrict flow of the molten material out of the shell.

Apparatus and method are provided for electric induction heating and/or stirring of a molten electrically conductive composition in a containment vessel with the apparatus being removably insertable in the molten composition. An induction coil embedded in refractory or a coating is submerged in the composition and used to heat and/or stir the molten composition either externally or internally to the refractory or coating.

The invention relates to a dental firing or press furnace (10) that enables the production of at least one dental restoration part (62). The dental firing or press furnace is provided with a firing space (12) that is heatable with the aid of a heating device (22), preferably, a resistance heating device. A heat-conducting element (50) having a specific thermal conductivity of at least 100 W/mK is arranged on the floor of the firing space (12).

The invention relates to a furnace slag door, comprising at least one panel which is moveable, in a mounted state of the slag door, from an opened position, in which the panel is remote from a corresponding slag discharge opening within the furnace wall to a closed position, in which the panel covers at least part of said slag discharge opening. The invention further comprises a corresponding furnace equipped with such slag door. The furnace is, in particular, an electric arc furnace (EAF) but may be as well of another type.

A method for treating spheroidal graphite iron includes the step: pouring molten spheroidal graphite iron into a pouring electrical furnace (1); covering the molten spheroidal graphite iron (5) with alkali slag (6) which is melted at high temperature and rich in alkali earth metal ion, rare earth metal ion, or mixture of them; connecting the molten spheroidal graphite iron (5) with the negative pole of the direct current source by one pole (7); connecting the alkali slag (6) with the positive pole of the direct current source by another pole (4), treating the molten spheroidal graphite iron (5) with the alkali slag (6) which is used as electrolyte. The method can prevent the spheroidized fading velocity of the spheroidal graphite iron. The pouring electrical furnace can be used for treating the molten spheroidal graphite iron.

A low temperature melting furnace using an external cooling passage includes a wall including a plurality of metal sectors, each metal sector including a cooling passage formed along a longitudinal direction thereof, and an extension tube provided outwardly from the wall and connected to the cooling passage.

A roof system for an electric arc furnace includes a skew removably attached to the electric arc furnace, a lining of refractory material affixed to the skew, and a delta composed of a refractory material. The delta has at least one aperture capable of receiving an electrode. The delta fits onto and is supported by the refractory lining that is affixed to the skew.

A resonant power supply (900) for use with high inductive loads includes an input rectifier (903) and a switching inverter formed using a plurality of parallel connected half bridge networks for switching the voltage provided from the input rectifier (903). A transformer (927) is used whose primary is connected to the switching inverter and whose secondary is connected to load such as a crucible (931). A capacitor (929) is used in series with the primary of the transformer (927) for resonating the inductance in the secondary circuit at the frequency of the switching inverter to provide maximum power transfer to the crucible (931).

A device (10) for adjusting the locking point of the electrode of a smelting furnace includes a vice (120) for supporting said electrode and supplying it with power. A structure (13) is coupled with the vice (120), supports the electrode and moves the electrode vertically.

A movable device for injecting oxygen and other technical materials into an electric arc furnace includes a housing situated above a portion of a step of a crucible and equipped with a cooling coil, an injection lance of oxygen and other technical materials, a supporting and moving system of the lance between minimum and maximum range points of the liquid bath level contained therein, positioned in the housing, an opening situated in the housing and facing the inside of the crucible in which the lance is transferably guided, and a scraping member disposed between the opening and the lance.

A support arm for a water-cooled, current-conducting electrode includes wall elements, wherein each wall element is a flat conductive metal with a hollowed out recess on its outer surface extending over its length. The support arm further includes a cover extending over each recess to define a closed cooling channel within each wall element when the cover is welded to the wall element. The cover includes with an inlet port and an outlet port for cooling water.

An integrated process control installation is provided for electric induction metal melting furnaces with variable furnace states. The integrated process control installation can include supporting charge delivery and slag removal installations, and furnace process operations for process control of melting metal in the furnaces. The variable furnace states, supporting installations, and furnace process operations are controlled by a supporting processing installation, while a robotic apparatus performs the furnace process operations.

Thermoplastic pellitized materials are melted in gravity flow through coaxially oriented perforated cylindrical metal susceptors. The susceptors are equally energized by the interception of a common magnetic field formed by a high frequency powered inductor coil.

The present invention relates generally to a ladle metallurgy furnace having an improved roof structure. The improved roof may comprise an internal surface structure having a substantially smooth exterior surface, an external surface structure spaced apart from the internal surface structure, a plurality of channels that are defined intermediate the internal and external surface structures, a supply port in fluid communication with at least one channel through the second surface structure and in further fluid communication with a supply line, and a return port in fluid communication with at least one channel through the external surface structure and in further fluid communication with a return line.

A device is described for generating a control signal for controlling a passenger protection arrangement of a motor vehicle, having a first acceleration sensor for generating a first acceleration signal, having a second acceleration sensor for generating a second acceleration signal, having a first structure-borne noise sensor for generating a first structure-borne noise signal, having a second structure-borne noise sensor for generating a second structure-borne noise signal, and having an evaluation circuit, the evaluation circuit (being configured for generating a combination signal from the first structure-borne noise signal and the second structure-borne noise signal, the evaluation circuit being configured for generating the control signal as a function of the first acceleration signal, the second acceleration signal and the combination signal.

Apparatus and process for heating and melting a material in a susceptor vessel are provided wherein phase synchronized ac voltage is supplied from a separate power source to each one of at least two induction coils in separate zones around the vessel. Power magnitude from each source to an induction coil is controlled by pulse width control of the source's output voltage. Output frequency from each source is either fixed or variable based upon the electrically conductive state of the material. Optional electromagnetic stirring is achieved by establishing a phase shift between the voltage outputs of the power supplies after the material in the susceptor vessel has melted.

Method of manufacturing a fused silica crucible, including manufacturing a plurality of carbon electrodes for melting a vitreous silica object to be melted by arc discharge by rubbing the surface of a carbon electrode of the electrodes with a vitreous silica of the same type as the vitreous silica object to be melted, by at least one of: inserting a front end of the carbon electrode into a storage tank storing powdered vitreous silica, by at least one of rotating and reciprocating in an axial direction the storage tank and the carbon electrode relative to each other; rubbing the surface of the carbon electrode by ejecting powdered vitreous silica from a nozzle onto the surface of the electrode; rubbing the surface of the electrode with a vitreous silica grinder; and rubbing the surface of the electrode against a rotating surface of a portion of a fused vitreous silica crucible.

An apparatus for casting metals by a nucleated casting technique to create a preform, the apparatus including a mold having a base and a side wall where the base can be moved relative to the side wall to withdraw the preform as it is being created. In various circumstances, portions of a droplet spray created by an atomizing nozzle, i.e., overspray, may accumulate on a top surface of the side wall and prevent or inhibit the preform from being moved relative to the side wall. The atomizing nozzle can be oriented such that the droplet spray passes over the top of the side wall to remelt and remove at least a portion of the overspray that has accumulated thereon. The mold can be rotated such that the overspray formed on a region of or on the entire perimeter of the top surface can pass through the droplet spray and can be removed from the side wall.

The present invention provides a shaft high temperature continuous graphitizing furnace comprising a furnace body comprising a feeding inlet and a discharging outlet, an electrode pair, a cooling system and a discharging device; the furnace body is designed to be a shaft cylindrical structure; the electrode pair is provided within the furnace body and comprise an upper electrode and a lower electrode, the upper electrode is located below the feeding inlet, and an umbrella or cone table shape electric field having a lower cross section area greater than its upper cross section area arises between the upper electrode and eh lower electrode; and the cooling system is located between the lower electrode and the discharging outlet. For the shaft high temperature continuous graphitizing furnace of the present invention, a perpendicularly placed column electrode is used as the upper electrode, a horizontally placed circular hollow electrode is used as the lower electrode, an umbrella high temperature area is formed between the electrode pair, and the natural flow law of an object is used to have materials pass a high temperature graphitizing area and then discharged, which ensures the quality of the product.

A heating electrode assembly for a crystal growth furnace includes: a heat insulation board unit that is disposed between a furnace wall and a heater, that includes a first surface facing the furnace wall and a second surface facing the heater, and that is formed with a hole extending through the first surface and the second surface; an electrode unit that includes an electricity input portion mounted to the furnace wall, a post portion disposed in the hole, and an abutment flange connecting the post portion and the heater; and an electrical insulating unit including a tubular sleeve that is disposed in the hole and that surrounds the post portion, and a pad that is clamped between the abutment flange and the second surface.

A furnace for dehydrating and sintering a porous glass preform includes a core tube that passes through a center portion of a furnace body to accommodate therein the porous glass preform, a heater that is arranged around the core tube in the furnace body to heat the porous glass preform in the core tube, and a core tube weight dividing and bearing means that is arranged at an outer periphery of the core tube to divide and bear the weight of the core tube in its longitudinal direction. The core tube weight dividing and bearing means includes a plurality of collars that is protruded at a predetermined interval in the longitudinal direction at the outer periphery of the core tube, a first weight receiving means that supports the collars at the outer periphery of the core tube, and a second weight receiving means that bears the weight of the first weight receiving means.

A method is provided to control the feed of a metal charge into an electric arc furnace having at least one electrode to generate an electric arc to melt metals. The method includes: a step of defining a “cover index CI” of the electric arc by the slag present above the liquid metal bath, in order to calculate which of the harmonics present in an electric feed quantity of the furnace are taken into consideration; a step of measuring the actual cover index CI value during a functioning cycle of the furnace; and a step of adjusting the speed of feed of the metal charge into the furnace based on the measured value of the cover index CI.

Disclosed herein are a graphite crucible for electromagnetic induction-based silicon melting and an apparatus for silicon melting/refining using the same, which performs a melting operation by a combination of indirect melting and direct melting. The crucible is formed of a graphite material and includes a cylindrical body having an open upper part through which a silicon raw material is charged into the crucible, and an outer wall surrounded by an induction coil, wherein a plurality of slits are vertically formed through the outer wall and an inner wall of the crucible such that an electromagnetic force created by an electric current flowing in the induction coil acts toward an inner center of the crucible to prevent a silicon melt from contacting the inner wall of the crucible.

Systems and methods are provided for a high performance heater. In an embodiment, the high performance heater comprises a first stackable tray comprising a first alignment pin that insulates a first heating element disposed in the first stackable tray; a second stackable tray comprising a second alignment pin that insulates a second heating element disposed in the second stackable tray, wherein a top of the first alignment pin fits into a cutout of a bottom of the second alignment pin when the first and second stackable trays are stacked, and wherein the first and second stackable trays comprise one or more materials, an outer diameter and an inner diameter, and wherein an area between the outer diameter and the inner diameter of the stackable trays comprises at least one cutout portion that allows expansion of the material(s) when the high performance heater is at high temperatures.

A graphite crucible for electromagnetic induction-based silicon melting and an apparatus for silicon melting/refining using the same, which performs a melting operation by a combination of indirect melting and direct melting. The crucible is formed of a graphite material and includes a cylindrical body having an open upper part through which a silicon raw material is charged into the crucible, and an outer wall surround by an induction coil, wherein a plurality of first slits are vertically formed through the outer wall and an inner wall of the crucible, and a plurality of second slits are vertically formed from an edge of the disc-shaped bottom of the crucible toward a center of the bottom.

A method for refining and casting metals and metal alloys includes melting and refining a metallic material and then casting the refined molten material by a nucleated casting technique. The refined molten material is provided to the atomizing nozzle of the nucleated casting apparatus through a transfer apparatus adapted to maintain the purity of the molten refined material. An apparatus including a melting and refining apparatus, a transfer apparatus, and a nucleated casting apparatus, in serial fluid communication, also is disclosed.

An electromagnetic induction melting furnace to control an average nominal diameter of the TiB2 cluster of the Al—Ti—B alloy includes a main body containing the melted alloy; and a multi-layer coil disposed on the main body, wherein a frequency of the alternative current of each coil of the multi-layer coil is different, and the alloy is heated by inducing a magnetic field generated by the alternative currents. The selection of the frequency and the changeable magnetic field may reduce the cohesion force between the TiB2 grains of the Al—Ti—B alloy to control the average nominal diameter of the TiB2 cluster.

An electromagnetic induction melting furnace to control an average nominal diameter of the TiC cluster of the Al—Ti—C alloy includes a main body containing the melted alloy; and a multi-layer coil disposed on the main body, wherein a frequency of the alternative current of each coil of the multi-layer coil is different, and the alloy is heated by inducing a magnetic field generated by the alternative currents. The selection of the frequency and the changeable magnetic field may reduce the cohesion force between the TiC grains of the Al—Ti—C alloy to control the average nominal diameter of the TiC cluster.

An electrode for a resistance analytical furnace has a crucible-engaging surface and an end spaced from the crucible-engaging surface having a plurality of grooves formed therein. A manifold mounted on the end of the electrode defines a dust recovery plenum and includes an outlet communicating with the plenum for coupling to a vacuum source to remove debris from the electrode. The improved electrode and electrode cleaning manifold positioned on the electrode provides a turbulent airflow for removal of dust and debris from an analytical furnace.

In one aspect, the invention is directed to a decoupler assembly for between an endless drive element and a shaft. The endless drive element may be, for example, an accessory drive belt from a vehicular engine. The shaft may be, for example, the input shaft of a belt-driven accessory, such as an alternator or a compressor. The decoupler assembly includes a hub that mounts to the shaft, a pulley that is rotatable with respect to the hub, a dampening spring and a clutch member. A part of the pulley is supported on a pulley support surface on the hub. There is a gap between the pulley and the pulley support surface. The gap has lubricant therein to facilitate sliding between the pulley and the pulley support surface. By eliminating the use of a polymeric bushing between pulley and the hub, there are several advantages that are provided.

Structure of a cross universal joint is achieved in which the fact that an excessive torque was applied to a universal joint due to a collision accident or mishandling can be easily determined afterwards. Protrusions 20, which are straight lines as seen from the outside surface sides of linking arm sections 15c of a yoke 12c, are formed on the outside surfaces of the linking arm sections 15c. When an excessive torque acts and the linking arm sections 15c are plastically deformed, the protrusions 20 change from a straight line to a non-straight line. From this change it is possible to easily confirm that an excessive torque has been applied to a cross universal joint that includes this yoke 12c. Moreover, when the space between the inside surfaces of the linking arm sections 15c is taken to be D, and the length in the axial direction of the linking arm sections 15c is taken to be L, the dimensions of the parts of the yoke 12c are regulated so that the relation 3

A coupling means (10) provided with a first member (20) suitable for being fastened to a first rotary part (2) and with a second member (30) suitable for being fastened to a second rotary part (3), the first member (20) being provided with a first diaphragm (22) and the second member (30) being provided with a second diaphragm (32) that is secured to the first diaphragm (22). An emergency torque transmission device comprises at least one bayonet system including a protuberance (50) secured to one member (30) and co-operating with an angled groove (60) secured to the other member (20) by being inserted in the angled groove (60) by a thrust-and-rotation movement, in the absence of said breakage said coupling means (10) including both axial clearances in compression (70') and in translation (70″) and also circumferential clearance between each protuberance (50) and walls defining the corresponding angled groove (60).

A starting device of a spark-ignition multi-cylinder engine is provided. The device includes a multi-cylinder engine body having cylinders, fuel injection valves, ignition plugs, an intake valve drive mechanism for opening and closing intake valves, a hydraulic variable valve phase mechanism for changing a close timing of each intake valve, an engine-driven hydraulic pressure supply source for supplying a hydraulic pressure, and a start controller for controlling the fuel injection valves, the ignition plugs, and the variable valve phase mechanism. When the supplied hydraulic pressure is below a predetermined pressure, the variable valve phase mechanism locks the close timing. When an engine temperature in an engine-start is high, the start controller retards a fuel injection timing of the cylinder on intake stroke at an engine stopped timing and retards an ignition timing thereof. The start controller does not retard the close timing of the intake valve until the engine-start completes.

An input shaft assembly is movable along an axis to absorb external impact loads. A biasing member exerts an axial load in a direction counter to potential impact loads. A stop is provided to control the application of biasing loads to control application of such axial load.

A torque limiting device, particularly for power transmission elements, is provided. The torque limiting device includes a first connecting member and a second connecting member, which is connected rotatably to a driven element. The first connecting member includes a motor driving disk and the second connecting member includes a sliding disk, and further includes a pin supporting body which comprises a drum that is assembled on the second connecting member and includes a plurality of radial holes, each one of which accommodates a pin that is pressed, toward the center of the drum, by elastic means, and abuts, with at least one of its faces which is inclined with respect to the central rotation axis of the second connecting member, against at least one corresponding abutment face.

A vibration damper, including a cover plate with an annular portion, and a spring portion including spring retaining portions forming respective spaces and a spring blocking portions including respective protrusion segments and respective tab segments including respective portions of an edge of the cover plate and having a same first thickness. The damper includes springs at least partially located in the respective spaces, and having respective longitudinal ends, and a second cover plate or output flange connected to the cover plate. The springs are arranged to transmit torque to the cover plate. The respective protrusion segments have a same second thickness and include respective protrusions. Respective first portions of the longitudinal ends of the springs are engaged with the respective protrusions. Respective second portions of the longitudinal ends of the springs are engaged with the respective tab segments.

A flexible shaft coupling demonstrates a high performance in transmitting torque and accommodating positional deviations, and is yet highly durable. A first elastomer member (82) having a relatively high rubber hardness is circumferentially interposed between a first claw (32) of a first shaft coupling member (20) and a second claw (62) of a second shaft coupling member (50), and a second elastomer member (84, 86) having a lower rubber hardness than the first elastomer member is interposed between a surface portion (end surface) (30) of the first shaft coupling member (20) and the second claw (62) and/or between a surface portion (end surface) (60) of the second shaft coupling member (50) and the first claw (32).

A torque fluctuation absorber includes a first rotating member, a second rotating member arranged coaxially with the first rotating member, a control plate arranged between the first rotating member and the second rotating member in an axial direction and engaging non-rotatably with the second rotating member, a thrust member arranged between the first rotating member and the control plate in the axial direction, engaging with the first rotating member in an axially movable and non-rotatable manner, and slidably making contact with the control plate, and an elastic member arranged between the first rotating member and the thrust member in the axial direction, supported by the first rotating member and pressing the thrust member against the control plate.

A fixed type constant velocity universal joint has pairs of track grooves, each pair forming a wedge angle (α). The wedge angle (α) includes a wedge angle (α0) formed, when an operating angle is 0°, with respect to each of torque transmitting balls arranged in a joint center plane, and opening to the same side in an axial direction for all pairs of track grooves. Further, the pairs of track grooves are mirror-image symmetrical with each other when the operating angle is 0°.

A driveshaft containment system and a method of its use. In preferred embodiments, the invention takes the form of a two component system including a first component mounted to a device such as a differential housing, coupled to driveshaft, and a second component comprising a tubular driveshaft containment housing. A driveshaft containment ring is preferably mounted to the forward end of the tubular housing which in turn is provided with a mechanism at its rearward end for rotationally engaging and disengaging the first component. The first and second components are also provided with a mechanism for preventing relative rotational movement of the first and second components while engaged with one another.

A device for damping vibrations in a drive train, in particular for plug screws in the pulp and paper industries. The device is principally characterized in that a cylindrical shaft, preferably designed as a hollow shaft, is provided, wherein the cylindrical shaft is arranged between the halves of a coupling and at least one ring having friction surfaces is arranged around the cylindrical shaft. Stick-slip vibrations that occur can thereby be favorably eliminated, and thus the gearbox and the motor of the drive train can be protected.

A variable valve actuating apparatus includes: a first rotary member which includes a rotor fixed to one of the inner cam shaft and the outer cam shaft, and a receiving chamber formed within the first rotary member, and which is arranged to be rotated in an advance angle direction or in a retard angle direction relative to the drive rotary member by a hydraulic pressure selectively supplied to or drained from the advance angle operation chamber and the retard angle operation chamber; and a second rotary member fixed to the other of the inner cam shaft and the outer cam shaft, rotatably received within the receiving chamber of the first rotary member, and arranged to be rotated relative to the first rotary member and the drive rotary member within a predetermined angle range.