Abstract: An internal combustion engine is disclosed which comprises first and second cylinder units each including at least one cylinder, an intake manifold divided into first and second intake passages leading to the first and second cylinder units, respectively, and an exhaust passage leading from the first and second cylinder units. The second intake passage has therein a normally open stop valve. The second intake passage is connected to the exhaust passage through an EGR passage having therein a normally closed EGR valve. Control means is provided for providing a control signal to disable the second cylinder unit when the engine load is below a predetermined value. The control signal is applied to valve drive means which thereby closes the stop valve and opens the EGR valve. The valve drive means is constructed to prevent the simultaneous opening of the stop and EGR valves.

Abstract: A supporting device (8) of a vehicle seat head rest (4) includes a retainer (6, 40) provided with a spring (10, 21, 44) which surrounds a supporting rod (5) of the head rest and resiliently engages therewith to support the head rest (4) at a desired height which can be adjusted in a stepless manner. The frictional retaining force of the spring can be released by an operating member (11, 20, 40) when the height of the head rest is to be adjusted. A cylindrical guide member (7, 41) serves to guide the adjusting movement of the supporting rod (5).

Abstract: A switch for sensing a preset position of a throttle valve in an internal combustion engine, includes a stationary casing, a plunger movably disposed in the casing, and a throttle lever secured to the throttle valve so as to be moved along with the throttle valve. A first contact is supported on the casing. A second contact is supported on the plunger in such a manner as to contact the first contact according to the movement of the plunger. The throttle lever is so arranged as to be able to move the plunger and as to encounter the casing when the throttle lever moves, whereby the first and second contacts contact according to the movement of the throttle valve and the casing stops the movement of the throttle valve.

Abstract: A fluid propeller fan useful as but not limited to an air-circulating cooling fan for an automotive engine, wherein each of the vanes of the fan has a pitch angle which is gradually reduced from the tip or an intermediate portion toward the radially innermost end of the vane so as to provide an increased draught volume and improved draught flow characteristics.

Abstract: A system for controlling the air-fuel ratio for an internal combustion engine comprises an O.sub.2 sensor for detecting the concentration of a constituent of exhaust gases passing through the exhaust passage, a carburetor for supplying air-fuel mixture to the induction passage of the engine, electromagnetic valves for correcting the air-fuel ratio of the air-fuel mixture supplied by the carburetor, a comparator for comparing the output signal of the O.sub.2 sensor with reference to a reference value, an integrating circuit having a proportional circuit for integrating the output of the comparator, a driving circuit for driving the electromagnetic valve in dependency upon the output signal of the integrating circuit.

Abstract: An automobile door structure comprises a door body formed with a door cavity therein, a window sash secured to the door body for guiding and retaining a windowpane, and a reinforcing member housed in the door cavity and secured at its front and rear ends to the window sash.

Abstract: A first circuit is provided for producing an output which changes at a certain rate by an amount corresponding to a predetermined crank angle in the direction of retarding a spark timing each time a knocking determination signal, representing that knocking occurs, is inputted thereto with a frequency higher than a predetermined frequency and an amplitude larger than a predetermined amplitude. The output from the first circuit further changes at a smaller rate than said certain rate in the direction of advancing the spark timing in the absence of the knocking determination signal. A second circuit is provided for outputting a waveform which is reset each time a spark command signal is inputted thereto and which thereafter changes to a predetermined level at a rate depending upon the rotational speed of the engine. A third circuit is provided for comparing the outputs of the first and second circuits to output a pulse signal of a duration depending upon the level of the output of the first circuit.

Abstract: An axle having a shallow "U" shape is oriented beneath the vehicle so that side and bottom sections of the U-shape extend either forward or are angled slightly downward and connected to the chassis through trailing links of different lengths whereby the axle rotates during vertical movement of the road wheels. The axle is disposed in the vehicle so that as the axle moves vertically, the ends of the axle pivot up on either side of a tire housing while the center or inboard portion moves through a smaller distance into a clearance between the tire housing and a fuel tank.

Abstract: When the temperatures of engine coolant and outside-air are above respective predetermined values immediately after the engine has stopped, a fan to cool the engine is operated for a predetermined time interval, thereby preventing engine compartment from being heated excessively.

Abstract: Herein disclosed is a radiator grille structure for attachment to the front end of an automotive vehicle having a fore-and-aft direction, comprising a stationary grille to be secured to the vehicle body of the automotive vehicle and comprising a plurality of horizontally elongated lamellar plates vertically spaced apart from each other and respectively having front end portions bent downwardly and forwardly for forming therebetween gaps to pass ram air therethrough, a movable grille comprising a plurality of horizontally elongated lamellar plates vertically spaced apart from each other and respectively having front end portions bent downwardly and forwardly, the lamellar plates of the moveable grille being arranged alternately to the lamellar plates of the stationary grille, the movable grille being movable in the fore-and-aft direction with respect to the stationary grille so as to cause the front end portions of the lamellar plates to move toward and away from positions closing the gaps, respectively, and d

Abstract: An internal combustion engine is disclosed which comprises first and second cylinder units each including at least one cylinder, sensor means for providing a signal indicative of engine vibration, and control means for disabling the first cylinder unit when the engine load is below a predetermined value. The control means is adapted to hold the first cylinder unit active, regardless of engine load conditions, when the engine vibration indicative signal exceeds a predetermined value indicative unstable engine operation.

Abstract: A retainer (21) for securing an article, e.g. a seat cushion, to a vehicle body consists of plastics-made hollow main body (22) which is inserted into an opening (8) in a vehicle body panel (6). The main body is provided on its outer surface with projections (26, 27a, 27b) which engage with upper and lower surfaces of the panel to prevent withdrawal of the retainer. The main body has an inner space with an open top end (22a) which permits insertion of a frame portion (2, 30) of the seat cushion into the inner space. The main body is further provided on its inner surface with projections (24a, 24b) which prevent withdrawal of the frame portion from the inner space. The inner space is open at the top end only, at least when the frame portion is retained in the inner space, so as to prevent entry of water or dust into the cabin even when the space below the body panel is not closed.

Abstract: A control apparatus for a power-assisted vehicle steering system, comprising a power cylinder having two pressure-acting chambers, a control valve having inlet and outlet ports respectively communicable with a pump and a fluid reservoir and selectively with the inlet and outlet ports, a pressure compensating valve having an inlet port communicating with the pressure-acting chambers, outlet and control ports and a valve member for varying the degree of communication between the inlet and outlet ports, the fluid pressure in the inlet port being variable with the fluid pressure from the pump and urging the valve member to move in one direction and a spring urging the valve member to move in the other direction to maintain constant the differential pressure between the inlet and outlet ports, and a pressure reducing valve having an inlet port communicating with the outlet port of the compensating valve, a discharge port communicating with the reservoir and the control port of the compensating valve and a valve me

Abstract: A watchdog-type fail-safe system monitors program execution by a computer used, e.g., in controlling operation of an automative vehicle engine. The system includes a control unit, with a microprocessor; and a memory, which stores program segments. These segments include a main routine for performing a background job (BGJ), and a plurality of interrupt routines for handling event generated interrupts. Completion of the BGJ causes transition of an emergency decision signal, provided by the control unit, to a first level. Initiation of a particular first interrupt routine causes transition of the decision signal to a second level. Abnormalities in program execution may result in non-transition of the decision signal. If there is non-transition of the decision signal for greater than a predetermined reference time period, a fault condition signal is generated. This may initiate various emergency procedures, e.g., stopping or resetting the computer, and visual or audio alarms.

Abstract: A dial type wire control device includes a drum and a strap or band in combination. The drum is connected to a dial member through a connecting shaft so that the drum and the dial member can rotate synchronously. The band is to be wound on the periphery of the drum when the drum rotates in one direction and to be unwound when it rotates in the opposite direction. Thus, the wire is pulled or pushed to control a subject in a conventional manner.

Abstract: In a disc brake of a type having a caliper slidably supported and having, on one side of a disc, a cylinder containing therein a piston for loading an inner pad against the disc and, on the other side of the disc, a limb portion for loading an outer pad against the disc, the flexural rigidity of the limb portion is made less on a leading side thereof located upstream with respect to the rotational direction of the disc for loading a leading or upstream side of the outer surface of the outer pad relating to a trailing side of said limb portion located downstream with respect to the rotational direction of the disc for loading a trailing or downstream side of the outer surface of the outer pad, so as to prevent frictional vibrations of the outer pad.

Abstract: An instrument panel supporting structure having a switch support member provided with manually operated electric switches and positioned inside the rim portion of a steering wheel of a steerable vehicle, wherein the switch support member having recesses therein is rotatably mounted on the steering shaft and a slider support member having a plurality of sliders slidably supported thereon is secured to the steering column tube and wherein the sliders are urged to protrude into the recesses, respectively, in the switch support member so as to provide engagement between the switches and slider support members and to prevent the switch support member from rotation with respect to the slider support member. When the steering wheel is turned and a radial spoke portion of the steering wheel is brought into engagement with any one of the sliders, the particular slider is forced by the spoke portion to retract away from the recess in the switch support member and permits the spoke portion to move past the slider.

Abstract: In a heating apparatus for motor vehicles, there is provided means for permitting part of air just heated by heater means provided in the apparatus to be directed toward a region upstream of the heater means so as to be again heated by the heater means, thereby causing the temperature in the vehicle chamber to be rapidly elevated, while at the same time preventing the humidity therein from being increased.

Abstract: An automobile air conditioning system is provided with a control system for controlling the flow rate of hot or cool air discharged into the passenger compartment. The air flow rate is controlled in relation to the sensed value of the ambient air temperature and the temperature of a heat source of the air conditioning system. If the sensed temperatures are lower than predetermined reference levels, the air flow rate is gradually increased at a moderate increasing rate. The air flow rate is more rapidly increased when the sensed heat source temperature is higher than the reference level.

Abstract: Disclosed is a paste containing an electrically conducting powder, which is a mixture of a platinum powder and a ceramic material powder in a proportion in the range from 51:49 to 78:22 by volume and has a specific surface area of 1.0 to 10.0 m.sup.2 /g, uniformly dispersed in an organic liquid vehicle in a proportion in the range from 70:30 to 50:50 by weight. A cavity in a ceramic substrate of an electric device having two, or more, conducting parts separately fixed to the substrate is filled up with this paste, and subsequently the substrate is fired to sinter the paste in the cavity into a conducting solid filler which provides electrical connection between the two conducting parts with low resistance and close and firm contact with the conducting parts and wall surfaces defining the cavity.

Abstract: An improved vehicle seat structure for a two-door type automotive vehicle having only a pair of front doors is inclinable about a pivot between front legs of front seat and floor panel. A pair of rear legs are releasable from the floor panel and pivotably secured to the seat. Actuator means operates to fold the rear legs below the seat responsive to inclining of the front seat so as to broaden the passage for letting on or off of passengers sitting in the rear seats of the vehicle.

Abstract: An air-fuel ratio control system for an internal combustion engine having an O.sub.2 -sensor for detecting the concentration of oxygen of exhaust gases passing through the exhaust passage, an electromagnetic valve for correcting the air-fuel ratio of the air-fuel mixture supplied by a carburetor, a feedback control circuit comprising a judging circuit for judging an output signal of the O.sub.2 -sensor and a driving circuit for driving the electromagnetic valve in dependency on an output signal of the judging circuit for controlling the air-fuel ratio to a value approximately to the stoichiometric air-fuel ratio. A Maximum and minimum value hold circuits respectively hold a maximum and a minimum value in one cycle of output variation of the detector. A first comparator compares the outputs of both hold circuits. A second comparator compares the output of the O.sub.2 -sensor with a predetermined level. A gate circuit is responsive to the output signals of the comparators for producing gate control signals.

Abstract: A communication system for automotive vehicles includes a fixed unit for transmitting an area signal at all times and information signals when requested and a mobile unit mounted on an automotive vehicle for receiving the area signal when the automotive vehicle passes through a communications area and for then transmitting a request signal to receive the information signals from the fixed unit. Since the electric field strength transmitted from the fixed unit is predetermined to be higher than that transmitted from a mobile unit in the case where two threshold levels for electric field strengths transmitted from both the units are equal to each other, it is possible to maintain a stable communications between both the units, even if electric field strength received by the mobile unit drops for some or other.

Abstract: An automobile air conditioning system is provided with a control system for controlling the flow rate of hot or cool air discharged into the passenger compartment. In this control system, the air flow rate is increased with an increase of the absolute value of the temperature difference between a predetermined reference temperature and a room temperature of the compartment detected by a sensor, and is decreased with a decrease of the absolute value.

Abstract: A shock absorber with improved shock absorbing characteristiscs has a piston in which a vortex chamber is formed. The vortex chamber communicates with upper and lower fluid chambers via communication passages. One of the communication passage opens to the vortex chamber tangentially to produce a vortex in the vortex chamber. Within the vortex chamber, a member is normally elastically urged to narrow the area through which the fluid flows. The member is responsive to the fluid pressure exceeding a predetermined value to move against the resilient force in the direction increasing the area allowing fluid flow. A bottom fitting of similar construction and function is also disclosed.

Abstract: An acceleration sensor acts on the variable-frequency pulses of a speed sensor signal to recognize any variation of the pulse period thereof and to produce an output indicative of the magnitude of the detected variation to within a fixed degree of accuracy. The periods of groups of known, variable number pulse groups are measured with reference to a fixed-frequency clock pulse signal and the measurement periods of successive groups of equal numbers of pulses are compared. If the difference between pulse group periods is zero or less than a predetermined value, the number of pulses in each group is increased in order to increase the total number of clock pulses during the measurement interval. The number of pulses per group is increased until the difference between measured periods exceeds the predetermined value or until the number of pulses per group reaches a predetermined maximum.

Abstract: A fuel supply control system for an engine includes a controller and a fuel supply line. In one embodiment, at least two parallel connected control valves are arranged in the line and are changed between open and closed states when energized by a drive signal. A sensor is provided for detecting an engine operating condition. A generator is provided for producing a random designation signal indicating any one of the different control valves. The controller produces a pulse train as the drive signal for the control valves in response to the output signal of the sensor so that the duty cycle of the pulse train varies with the engine operating condition. The controller distributes each pulse of the drive signal to any one of the control valves designated by the random designation signal of the generator to open the designated control valve so that any one of the control valves is opened in a random sequence. In a second embodiment, the number of the control valves may be one.

Abstract: In an oxygen sensor comprising an oxygen ion conductive solid electrolyte, an electronically conductive reference electrode layer formed on one side of the electrolyte layer, an electronically conductive measurement electrode layer formed on the other side of the electrolyte layer, and a partition layer of an electrochemically inactive material formed on the outer side of the reference electrode layer, at least one of the reference and measurement electrode layers has a plurality of openings through which two layers which put therebetween the one of the electrode layers are united with each other.

Abstract: A plasma ignition system having a plurality of plasma ignition plugs eliminates a mechanical distributor for sequentially distributing plasma ignition energy into each plasma ignition plug.

Abstract: A flow outlet structure for an automotive air conditioner which is equipped with a louver having a plurality of movable slats and a fluidic element to cyclically change the direction of flow laterally of the automobile as long as the angle of the slats of the louver are below a predetermined angle. When the slats of the louver takes an angular position greater than the predetermined angle, the flow of cool air in three diversified directions is provided.

Abstract: A system for resistance welding in which the welding voltage between the electrodes is controlled by changing the pressure applied to the electrodes or the firing phase angle of the welding current in accordance with a reference voltage curve or a reference voltage integration curve. The system comprises a voltage sensor, a reference voltage generator, a differential amplifier, and a pressure control device, or a calculating unit for determining an appropriate firing phase angle of the welding current. The system thus improved can ensure a stable, good welding quality, since the welding voltage is always controlled by a series of optimum welding voltages, during the welding process, in accordance with a reference voltage curve with respect to time, preferably in terms of cycles of the welding current.

Abstract: A method of impregnating spheres of activated alumina with cerium in an oxidized state. The cerium-impregnated alumina spheres are for use in catalyst supports for three-way catalysts for purification of exhaust gases of automotive engines. The method has the steps of wetting spheres of activated alumina with an aqueous solution of a cerium salt, drying the wet spheres and calcining the dried spheres in an oxidizing atmosphere. The drying is performed so as to complete the removal of water from the spheres by evaporation in a time period not longer than 10 min, preferably by subjecting the wet spheres to microwave heating and most preferably by performing the microwave heating with a forced draft. By quickly completing the drying the distribution of cerium in the individual spheres becomes very uniform, and this has the effect of improving the efficiency of three-way catalysts produced by using the cerium-impregnated spheres of activated alumina.

Abstract: In an internal combustion engine having at its intake section a two-barrel type carburetor including a primary fuel supply system having a primary main fuel supply line and a primary slow fuel supply line and a secondary fuel supply system having a secondary main fuel supply line and a secondary step fuel supply line, and at its exhaust section a three-way catalytic converter, there is provided an improved closed loop type air-fuel ratio control system which controls not only the amount of air fed to the primary main and slow fuel supply lines but also the amount of air fed to the secondary main and step fuel supply lines in accordance with the concentration of a selected component of the engine exhaust gas. A switching valve is associated with both the primary slow fuel supply line and the secondary main or step fuel supply line so as to alter the course of the air introduction into the primary slow fuel supply line or into the secondary main or step fuel supply line in accordance with the engine load.

Abstract: A head lining mounting structure for anchoring each end of a head lining to a vehicle structural member such as a roof rail includes an anchoring means formed in a multi-stepped manner to taken up irregularities in dimension or elongation of a head lining, thereby preventing slacks or wrinkles of the head lining and facilitating mounting the head lining on the vehicle structural member and therefore avoiding a spoiling of a sense of beauty or fine quality in a vehicle compartment due to mounting conditions of the head lining.

Abstract: Disclosed herewith an intake air flow rate control system for an internal combustion engine including a means for detecting acceleration and deceleration of the vehicle and controlling the air flow rate in response to required air flow rate which is varied by acceleration and deceleration of the vehicle. The means temporarily operates to vary the air flow rate at the time of acceleration or deceleration in which the throttle valve angle sensor turns between on to off or off to on. After increasing or decreasing the air flow rate responsive to acceleration or deceleration of the vehicle, the increased or decreased value is gradually returned to the normal control ratio at a given rate and a given timing.

Abstract: A license plate holder at the rear panel of a vehicle includes a plate holder member which affords a first flat surface portion and contiguous thereto a pair of second flat surface portions. The license plate is mounted on the first surface portion, and illuminating lamps for the license plate are mounted on the second surface portions. Standardized lamps having flat bottom surfaces are used as the illuminating lamps regardless of the shape of the rear panel, eliminating preparation of various types of the lamps.

Abstract: An engine mounting buffer rod is constructed to constitute two suspended masses interconnected by elastomeric means to endow on the rod two resonance frequencies. The resonance frequencies are selected to span the vibrational range in which resonance noise is apt to occur in the vehicle cabin so that a first change in the phase of vibration passing through the buffer rod causes an interference with the vibration passing through the main engine mounting brackets to soften the mounting arrangement as a whole and absorb vibrations which would otherwise induce cabin resonance noise. The effect of the second resonance overlaps the first to prolong the softening effect until the second phase change induced thereby occurs.

Abstract: A die for forging a part with internal, tapered grooves, for instance, such as a socket with a plurality of inner races used for a joint. The blank is formed into a given shape by a cylindrical projection provided in the upper die so as to compress the outer peripheral surface thereof, in cooperation with the liner-grooving dies, when the upper die is lowered. After the forging step, the locking pin inserted in the lower die is lowered so as to move the liner-grooving die toward the stamping axis so that the forged workpiece can be removed from the lower die easily and next ejected by the ejector pin.

Abstract: A hydraulic pump drive system for an automotive vehicle employing a starter motor to drive the hydraulic pump. The drive shaft of the starter motor is connected to the impeller of the pump, and can be engaged to the engine flywheel to start the engine. A control circuit is provided to connect the armature and the field winding or field windings of the starter in series for starting the engine and in parallel after the engine has been started. The control circuit also controls a valve in the hydraulic system which acts as a pressure-relief valve to minimize load due to the hydraulic pump on the starter motor during engine starting.

Abstract: Disclosed is an electronic automatic control method and system for controlling an air flow rate for an internal combustion engine of an automotive vehicle. The system includes an open loop control and a feedback control which are selectively effected corresponding to engine condition. The system includes an engine or temperature range within which the system controls engine speed. The given temperature range corresponds to a normal ambient temperature range so as to improve warming up efficiency upon starting engine under cold engine conditions. The system further includes a means for determining a feedback control condition to effect feedback control at a specific engine condition.

Abstract: A ventilator air outlet door having a curved portion, a downstream deflecting portion, and support portions is pivotally disposed within the bypass passageway formed within an air distribution housing and is pivotally swung between a first position closing a ventilator outlet when the defrosting or heating mode is selected, and a second position within the bypass passageway, opening the ventilator outlet when the ventilating mode is selected thereby the ventilator door guiding the air flowing through the bypass passageway desirable direction when the ventilating defrosting or heating mode is selected.

Abstract: A fuel supply system for an injection-type internal combustion engine using a gasoline or alcohol blended gasoline as a fuel. In addition to a conventional fuel supply system there is provided a fuel temperature detector which detects and signals the fuel temperature increases and exceeds a predetermined value and a fuel pressure regulating means responsive to the fuel temperature detector for raising the fuel pressure within the fuel supply line applied to each fuel injector above a constant value regulated according to the pressure difference between the fuel pressure within the fuel supply line and the intake manifold vacuum pressure so as to prevent the fuel supply line from being clogged due to the occurrence of vapor lock at the time when the engine is started at a high fuel temperature or when the engine runs at a low speed under a high fuel temperature.

Abstract: A fuel-supply control system for a gas-turbine engine includes a fuel injector opening into an engine combustion chamber, and a reservoir connected to the fuel injector. At least two different lines are each connected at one end to the reservoir. These lines are permitted to pass fuel therethrough to supply the fuel to the combustion chamber via the reservoir and the fuel injector. Metering valves whose number is equal to the number of the lines are arranged each in the lines in such a manner that the lengths of the lines from the corresponding metering valve to the reservoir are different from each other. The metering valves are changed from one of open and closed states to the other when energized. A sensor is provided for detecting a certain engine operating condition. A controller is connected to the sensor for producing a pulse train whose duty cycle depends on the engine operating condition. The pulse train is fed to the metering valves to open them periodically.

Abstract: A seat belt device used for a two-door automotive vehicle in which the seat back of the front seat is tilted forward whenever the passenger taking the rear seat gets out of the passenger compartment. In the seat belt device according to the present invention, since the seat belt is moved frontward along the side surface of the seat cushion by the use of a link mechanism, when the seat back is tilted forward, it is possible to open or close the vehicle side door smoothly without pinching the seat belt between the seat cushion and the seat back.

Abstract: A waste binding yarn take-up device for a shuttleless loom, comprises a traction device for pulling waste binding yarns at a constant traction speed, a rotary traverse roller rotatable at a peripheral velocity slightly higher than the traction speed of the traction device, and formed at its outer surface with a guide groove along which the waste binding yarns from the traction device is guided to make traverse motion thereof, and a rotatable core member on which a cheese of the waste binding yarns from the traverse roller is capable of being formed, the core member being biased so that the outer surface of the cheese contacts the outer surface of the traverse roller, thereby wounding up the waste binding yarns on the core member, holding in tension the waste binding yarns without causing the slackening of the waste binding yarns.

Abstract: A regulator handle assembly for the positional control of a car window glass includes a handle lever combined with a spring-loaded manual knob arranged slidable and rotatable on a hollow sleeve made at the free end of the handle lever integral therewith. This knob is slidable relative to the hollow sleeve and in the outward direction when manipulating the handle so as to enlarge the overall height thereof against action of a coil spring mounted within the knob. When the manual operating pressure is released, the knob is automatically returned to its height-shortened normal position under the influence of the coil spring.

Abstract: An internal combustion engine carburetor is disclosed which includes an induction passage provided therein with venturi means and controlled by throttle valve means, a fuel bowl connected through a main solenoid valve to a main fuel passage for discharging fuel through a main nozzle opening into the venturi means, a fuel pump connected through an auxiliary solenoid valve to an auxiliary fuel passage into which an air bleed opens for discharging fuel through a sonic nozzle opening into the induction passage downstream of the throttle valve means, and fast-idle mechanism for forcing the throttle valve means to open to a predetermined angle from its closed position. A control circuit is provided for providing a control signal corrected based on the density of atmospheric air, which corresponds to the rate of air flow through the induction passage for controlling the main and auxiliary solenoid valves. The control circuit is adapted to drive the fast-idle mechanism at low engine temperatures.

Abstract: A window structure of a vehicle body, comprises an inwardly offset flange structure defining a window opening therein, the inwardly offset flange structure including inwardly bent walls which have substantially straight wall portions and curved corner wall portions each merging into adjacent two of the straight wall portions; a window panel secured to the flange structure for closing the window opening, the window panel having an edge wall which includes a plurality of substantially straight edge wall portions respectively spaced apart from the straight wall portions and a plurality of curved corner edge wall portions each merging into adjacent two of the straight edge wall portions and respectively spaced apart from the curved corner wall portions, each of the straight edge wall portions and each of the straight wall portions forming a straight gap therebetween, and each of the curved corner edge wall portions and each of the curved corner wall portions forming therebetween a curved corner gap which merges i