Abstract: An anti-overrunning device for an internal combustion engine which includes a carburetor with a controlled throttle valve. An actuator for the throttle valve includes a spring-biased rod mounted on a diaphragm. The rod normally urges the throttle valve to a closing position. The actuator includes a pressure actuated diaphgram responsive to pressure from a vibrating pump. This pressure tends to open the throttle valve. A vibration sensor is positioned to relieve pressure on the diaphgram of the actuator and, in response to overrunning of the engine, causes the throttle valve to close in under the influence of the spring bias.

Abstract: An anti-overrunning device for an internal combustion engine utilizing a carburetor with a throttle valve and a vibrating pump for generating pressure by vibrations of the engine. An actuator is provided for the throttle valve to move it to a closing position, and a control valve is used to control flow of pressure from the vibrating pump to the actuator. A generator driven by the engine provides electromotive force to actuate the control valve.

Abstract: Herein disclosed in an oil degradation warning system which comprises several sensors for sensing parameters which are closely related to degradation factors of the engine oil, a microcomputer which processes the detected parameters to compute oil degradation coefficients of them in each factor, integrates the oil degradation coefficients in each factor with passage of time, and issues an instruction signal when at least of the integrated values of the oil degradation coefficients exceeds a corresponding reference value, and a warning device which gives a warning when the instruction signal is applied thereto.

Abstract: An engine control system of a marine outboard engine has an oscillator which operates in response to an abnormality signal resulting from detection signals from an oil level sensor and a temperature sensor, and in response to a signal from a tachometric sensor to transmit normal and retarded ignition signals alternately and repeatedly to a firing timing control circuit, which thereupon controls the engine ignition with normal firing timing when receiving the normal ignition signal and with retarded firing timing when receiving the retarded ignition signal. The engine power output under retarded firing time is lower than that under normal firing timing, whereby the engine emits an abnormal humming sound, warning the operator that an abnormal condition has occurred.

Abstract: An emergency control device for a diesel internal combustion engine with electronically controlled fuel proportioning, which enables an optimal emergency driving operation in case of a defect of the transmitter or transmitters for the actual value of fuel volume. In the event of an error, the mechanism determining the desired value of fuel volume during normal operation, and the fuel volume regulating device, are separated from the fuel proportioning device and the latter is controlled by a special emergency driving signal. An error in the transmitters for the actual value of fuel volume is recognized in that this signal does not fall in the allowable area for the actual value of fuel volume. A first signal, which, together with a second signal, gives the emergency driving signal, is formed from the speed and the accelerator position. The second signal consists substantially of the differentiated speed signal.

Abstract: An apparatus including a grip sensor for controlling the number of revolutions of an engine. The grip sensor detects whether or not fingers of an operator approach toward the grip sensor or the former come in contact with the latter. Usually, the grip sensor is incorporated in the gripping portion of a control lever which controls actuation of working tools. The apparatus includes a controller for outputting a deceleration signal in response to an output signal from the grip sensor in order to reduce the current number of revolutions of the engine to a level lower than the number of revolutions of the engine in the high operative state when no detection is achieved by means of the grip sensor. Alternatively, the controller may output an acceleration signal in response to an output signal from the grip sensor in order to raise the current number of revolutions of the engine to a level higher than that the engine in the idle rotational state when detection is achieved by means of the grip sensor.

Abstract: In a device for transmitting the position of a control element (1) which is actuatable by the driver of a vehicle between an idling position and a full-gas position via an electric set-value transmitter (2) which is displaceable by the control element and via electric transmission means, particularly a regulator (3), to a setting member (6) which is displaceable in corresponding manner between the idling position and the full-gas position, which member is coupled by coupling means (12, 13) to a actuating member which controls the fuel/air mixture of an internal combustion engine, an emergency-operation capability is to be obtained by a mechanical safety transmission element. For this purpose, the position of the control element is to be transmitted by the mechanical safety transmission element to the actuating member.

Abstract: An arrangement for supplying fuel from a supply tank to an internal combustion engine, particularly in a power vehicle, comprises a container, a feeding aggregate arranged in the container, two pump stages arranged in series in a flow direction of a fuel and sealed from one another, the pump stages including a pre-stage and an end stage and each having a suction opening and a pressure opening, and unit for warning about the dry running of the pre-stage and including a sensor which is arranged between the suction opening and the pressure opening of the pre-stage in a region of the feeding aggregate through which fuel flows, and a warning device operatively connected with the sensor and activated in response to dry running of the pre-stage.

Abstract: A low pressure fuel circulation with fuel preheating for an air-compressing injection-type internal combustion engine, preferably for commercial vehicles, in which a heat-exchanger and a by-pass by-passing the fine filter and having an excess pressure valve opening in dependence on a predetermined maximum pressure acting on the fine filter as a result of paraffin formation is arranged in an inlet line leading to a high pressure injection pump.

Abstract: A motor vehicle engine includes an operator controlled fuel injection enabling switch effective to disconnect electric fuel injection apparatus from an electric power source and thus initiate the cessation of engine operation when deactivated. However, the spark ignition system is still powered through an oil pressure switch so as to continue engine operation for a few extra crankshaft rotations to reduce the unburned fuel in the intake passage as the engine stops and thus reduce throttle bore coking. In a vehicle having a fuel pump relay activated by the fuel injection enabling switch with contacts connected across the oil pressure switch, the invention may be obtained by changing the power connection of the spark ignition system from the fuel injection enabling (ignition) switch to the fuel pump relay.

Abstract: In a marine drive having a wiring harness (14) connected between the engine (2) and the helm (8), an alarm sensing module (26) is connected to the harness (14) and provides a warning of one or more abnormal engine conditions, without altering the existing wiring harness or adding wires thereto. A temperature switch (30) and an oil pressure switch (32) are provided at the engine, and the sensing module (26) is connected to the engine temperature gauge (10) and engine oil pressure gauge (12) at the helm. The module activates an alarm (28) in response to high engine temperature or low engine oil pressure.

Abstract: A constant-speed running control device is provided, which comprises car speed detecting means for detecting the current car speed of a vehicle, memory means for storing a given car speed, an actuator for controlling a throttle valve, setting means for causing the memory means to store the given car speed, releasing means for releasing the control of the actuator, electronic control means for controlling the actuator in such a direction as to cause the difference between the stored car speed held in the memory means and the current car speed detected by the car speed detecting means to disappear, temperature detecting means, and low-temperature release means for actuating the releasing means in response to the output of the temperature detecting means, whereby the control of the actuator is released through the releasing means when an ambient temperature lowers to thereby prevent erroneous operation and enhance reliability.

Abstract: The invention includes a fuel tank containing an emergency supply of fuel for an internal combustion engine in the general proximity of the engine, with the arrangement being such that proper communication from this alternate source of fuel directly to the air-fuel mixer of the engine is effected. The preferred example of the air-fuel mixer is a carburetor. In this way, by utilizing a reliable arrangement for the delivery of fuel directly to the carburetor, a temporary problem with the primary fuel supply can be circumvented.

Abstract: In controlling ignition timing in accordance with a deviation between a target ignition timing determined on the basis of at least an engine load and an engine speed and an actual ignition timing detected by use of an ignition timing sensor, when non-perfect explosion operating conditions, wherein an ignition signal is difficult to detect, or operating conditions in which the ignition signal is instable are present, an open loop control on the basis of the engine load and the engine speed is effected. Feedback control is effected when the ignition signal is detected with neither non-perfect explosion operating conditions nor instable ignition signal operating conditions being present. When the ignition signal is not detected, the aforesaid open loop control is effected and a trouble in the ignition timing sensor is detected.

Abstract: This disclosure relates to a small craft including a hull, an engine and a fuel tank in the hull, and a fuel supply system for carrying fuel from the tank to the engine. The supply system includes a suction pipe having an inlet opening within the tank. A fuel retention device is connected to the pipe around the inlet opening and it retains fuel at the inlet opening to prevent air from entering the opening when the opening is above the fuel level for a short time.

Abstract: At least one hook or clip is mounted to the inside surface of the engine compartment hatch door so as to removably receive the engine oil dipstick so that the dipstick protrudes beyond an edge of the hatch door and prevents its full closure.

Abstract: An electronically regulated fuel injection system for an internal combustion engine with a switchable safety and emergency driving device has a mechanical coupling which mechanically couples the accelerator pedal to the regulator. This coupling operatively interferes with a mechanical connection between a controller and the final control element that determines the quantity of fuel to be injected, after a fault signal has been outputted by a signal processing unit to a switchover element, which switches over control of the final control element to the simple regulator.

Abstract: An improvement in a process for the press fit assembly of two parts having an interference fit, wherein one of the two parts is provided with a grooved surface. A pre-applied dry to-the-touch sealant, adapted to be cured upon assembly of the two parts, is applied on the grooves prior to assembly.

Abstract: A cooling system for an internal combustion engine equipped with an auxiliary fan, which is adapted to be selectively engaged and is arranged inside of a space adapted to be closed by means of a lid (engine hood); the fan is controlled in dependence on the position of this lid. Especially with an open engine hood, a sudden and unexpectedly occurring re-starting of the fan is avoided having been turned-off so that injuries to limbs of a servicing person who works in direct proximity of the fan is practically precluded.

Abstract: A throttle valve control device for an internal combustion engine controls an opening degree of a throttle valve by electrically drivingly rotating a rotary shaft, to which fixed is the throttle valve, in response to an angular movement of a speed acceleration pedal. The control device is actuated only in case of emergency. The control device is provided with a throttle valve returning mechanism for imparting a torque to cause the rotary shaft to rotate in a direction in which the throttle valve is fully closed.

Abstract: There is disclosed a fuel cutoff apparatus for use in an engine-driven vehicle. The apparatus comprises a fuel supply means for supplying fuel to the engine, a hydraulically actuated means that is actuated in response to the pressure of the engine oil, and a fuel cutoff control means which, when the pressure of the engine oil decreases below a certain level, is actuated in response to the actuation of the hydraulically actuated means to control the fuel supply means in such a way that the supply of fuel to the engine is cut off.

Abstract: A throttle valve is supported rotatably on a pipeline. The throttle valve is driven by a motor. A downstream side of the throttle valve is connected to an engine. A means for opening the throttle valve forcedly is provided so as not to allow a tar component in the fuel for driving the engine to stick on the throttle valve at an outer peripheral portion when the engine is shut down.

Abstract: A fuel injection pump for internal combustion engines is described, which for controlling fuel quantity is provided with control unit that controls an electric final control element, which in turn actuates the regulating member that determines the fuel injection quantity per pump piston supply stroke. The supply of fuel to the pump work chamber is effected from a fuel supply chamber, which is kept at a controlled pressure by a fuel feed pump. To limit the maximum speed of the engine supplied by the fuel injection pump in the event of failure of the control unit, a valve is provided in the intake line of the fuel feed pump. Using this valve, the flow cross section of the intake line can be varied or closed. By means of the modification of the fuel pressure in the fuel supply chamber effected thereby, a control of the fuel injection quantity that is not dependent on the position of the quantity-determining member is attained.

Abstract: A control system for controlling an internal combustion engine which is provided with at least one fuel injection pump which comprises for the control of the fuel injection pump a control rod, a servomotor, which is adapted to be mechanically coupled to said control rod, and a microcomputer for controlling said servomotor in dependence on operating conditions of the engine and on the position of an arbitrarily operable travel control lever. Means are provided for establishing a direct mechanical connection between the arbitrarily operable travel control lever and the control rod so that the latter can be moved under the control of the travel control lever in case of a failure of the electric system which comprises the sensors, the microcomputer and the servomotor.

Abstract: A method of safeguarding operation of an internal combustion engine is based on the provision of two electrically controlled fuel supply pumps delivering fuel from a tank to a fuel metering device. During the start of the engine both fuel supplying pumps are activated. During a normal engine operation when rotary speed exceeds an iling value, a random fuel supplying pump is turned off. In a defect situation resulting from malfunction of the active pump both pumps are turned on to maintain fuel supply by the other pump. In an emergency situation when for example actual rotary speed exceeds a maximum value, both fuel supplying pumps are activated in reverse to suck fuel from the metering device and cause the standstill of the engine.

Abstract: Described is an assembly that is interposed between the main fuel supply and the fuel injection system of a fuel-injected gasoline engine or diesel engine. When the main supply of fuel becomes exhausted, the assembly (i) automatically shuts off the flow of fuel to the fuel injection system, (ii) causes the engine to cease operating through fuel starvation, and (iii) prevents air from entering the fuel injection system. The assembly forms and utilizes a reserve supply of fuel and utilizes the vacuum created by the fuel-starved engine in such a way as to insure that no air becomes entrained in the fuel injection system when operation of the engine is resumed with a replenished fuel supply.

Abstract: A breakerless electronic ignition system including a permanent magnet assembly, a transformer, an electronic ignition circuit and a cut off switch. In one embodiment of the system, a charging coil charges up a capacitor. The capacitor is connected in series with an electronic switching device and a primary coil of the transformer. The transformer primary coil has one end connected to the cut off switch which is normally closed and which is connected to ground. When the cut off switch is in the open position, current is prevented from flowing through the primary coil whereas the electronic switching device continues to be triggered as the engine coasts to a stop. In an inductive embodiment of the system, the primary coil of the transformer is also lifted from ground by the cut off switch to stop further generation of ignition sparks.

Abstract: An alarm system for a two-cycle internal combustion engine having a lubricating oil pump and an alternator generating electric pulses at a frequency related to engine speed. An integrated circuit configured as a counter has an input connected to receive the alternator pulses. A pressure switch generates an electric signal in response to the oil pressure increase in the pump output each time the pump operates. The integrated circuit has a first output which changes logic state in response to a predetermined count and has a second output which changes value at a frequency related to engine speed. The signal generated by the pressure switch is connected to a reset input to the integrated circuit so the counter is reset to zero in response to each oil pressure signal. An SCR switch controls operation of an alarm horn. A control connected to the integrated circuit and to the SCR operates the horn at a frequency related to engine speed.

Abstract: The propulsion control system of a diesel-electric locomotive includes means responsive to the respective temperatures of the coolant and the lubricant of the locomotive engine for automatically indicating that the locomotive is in a tunnel if the coolant temperature exceeds an abnormally high magnitude and is higher than a variable reference level that depends on the lubricant temperature. When a tunnel is thus detected, the conventional overtemperature-responsive deration function of the propulsion control system is temporarily suppressed until the coolant temperature rises to a threshold that is higher than the preset overtemperature threshold at which deration is normally initiated.

Abstract: In order to obviate the need to manually input data relating to the grade of oil used to lubricate an engine, a monitoring system includes a sensor which senses the grade of oil along with sensors which enable the oil change procedure per se to be detected. After each oil change the output of the oil grade sensor is read and the appropriate values which determine the limits to which the oil may be permitted to degradate are automatically determined.

Abstract: A pump comprising a housing, an oil pumping chamber in the housing, an oil passageway in the housing communicating with the oil pumping chamber, an oil pumping piston reciprocally movable in the oil pumping chamber to produce oil flow into the oil passageway in response to reciprocation of the oil pumping piston, a switch mounted on the housing and adapted to be operably connected to a device for actuation thereof, and a mechanism for closing the switch in response to oil flow in the oil passageway.

Abstract: An ignition powered indicator system for detecting and audibly alerting an operator of a low oil condition associated with an internal combustion engine for apparatus such as a lawn mower, pump, generator, tractor and the like. The indicator system includes a low oil switch mounted on the engine crankcase housing and connected in circuit with a buzzer, diode, and capacitor with the ignition primary. When the oil level is too low, the switch closes shorting the ignition primary to shut off the engine and produce an intermittent beeping sound, namely, one beep per ignition pulse, alerting the operator of the low oil condition.

Abstract: An electronic and mechanical fuel feeding system comprises a mechanical fuel induction system coupled with an electronic fuel injection system through a diverter valve in fluid communication with a mechancial pump. The diverter valve includes a valve actuator responsive to an electrical signal to couple the inlet of the diverter valve with the outlet of the valve connected in fluid communication with electronically controlled injector nozzles. Alternatively, absence of an electrical control signal at the valve actuator causes coupling of the inlet of the diverter valve to a second outlet coupled in fluid communication with a mechanical carburetion system. In the preferred embodiment, the electronic fuel injection system comprises a control circuit responsive to changes in engine speed, manifold pressure, exhaust gas temperature and cylinder temperature so that accurately metered amounts of fuel are delivered by the injector nozzles to the engine cylinders.

Abstract: A device for detecting low engine oil levels includes a mechanism for detecting the presence of oil in an oil containment vessel for an engine. A housing is disposed in the containment vessel for enclosing the detection mechanism. A chamber is disposed in the housing and is adapted to permit the free flow of oil therethrough for contact with the detection mechanism according to the level of oil in the containment vessel. The chamber further prevents surging of oil therethrough resulting from movement of the vehicle carrying the engine as well as intermittent splashing of the oil on the detection mechanism resulting from operation of the engine.

Abstract: An engine starter device for a motor cycle including an engine, a primary transmission having a neutral gear position, and a secondary transmission having a reverse gear position. The engine starter device starts the engine only when the primary transmission is in the neutral gear position and the secondary transmission is not in the reverse gear position.

Abstract: A unit injector for an internal combustion engine has a solenoid valve for closing a fuel overflow passage to determine the injection timing and the injection quantity. A pumping plunger has its outer peripheral surface formed with first and second longitudinal slits both communicating with the plunger chamber, and a circumferentially extending suction slit communicating with the first longitudinal slit and registrable with a fuel intake passage when the plunger is in an extreme position remote from the plunger chamber. The plunger can assume selectively a normal operating position, a starting position, and an emergency stopping position, at respective different circumferential positions thereof. In the normal operating position, the plunger chamber communicates with the fuel intake passage through alignment of the first longitudinal slit or the suction slit with the fuel intake passage, and also communicated and with the fuel overflow passage via the second longitudinal slit.

Abstract: A method and apparatus is disclosed for continuing the cooling of an engine, such as a turbo-charged equipped truck engine, at times when the engine temperature is elevated. In the illustrated form of the invention, the temperature of the engine is sensed. An engine control circuit bypasses the ignition switch at times when the sensed engine temperature is above a predetermined temperature and prevents the ignition switch from shutting off the engine under such conditions. The engine continues to operate, even though the ignition switch is off, until such time as the engine cools and the sensed temperature drops to the predetermined reference level. The predetermined temperature is adjustable to vary the temperature at which the engine is allowed to shut off. The apparatus includes optional indicator and override mechanisms.

Abstract: A control system for protecting an internal combustion engine is disclosed. The system comprises input receiving means for receiving a plurality of warning signals, each representing a fault condition, and signal processing means for producing an engine shutdown command signal. The signal processing means includes means for classifying any received warning signal as one requiring a fast shutdown response or a delayed shutdown response.

Abstract: This disclosure relates to a water-cooled engine for a boat, including apparatus to prevent the engine from overheating due to a shortage of coolant. The apparatus includes an air intake connected to supply fresh air to the engine, and an exhaust system connected to discharge exhaust gas from the engine. A duct is connected between the air intake and the exhaust system, and a normally closed valve is provided in the duct. A heat responsive device is provided on the engine to open the valve in response to a predetermined high temperature of the engine, whereby at least a portion of the exhaust gas is fed back through the duct to the air intake.

Abstract: An engine protection apparatus that monitors several engine functions and that disables the engine in response to the detection of undesireable operating conditions. When ambient temperatures are low, an extended engine warm up period is provided; since the vehicle may be left unattended during an extended warm up period in a cold climate, the engine is monitored during the warm up period so that it may be disabled by the apparatus if an undesireable operating condition arises. Similarly, when ambient temperatures are high, an extended engine cool down period is provided; since the engine may be left unattended during the cool down period, the engine is monitored by the apparatus and disabled if an undesireable operating condition is detected. The apparatus also monitors the engine during its normal operating times, in addition to the warm up and cool down periods of time.

Abstract: This invention discloses apparatus for controlling the throttle of an aircraft engine so that it is either in the fully automatic electronic fuel control mode or in the completely manual mode while using a single throttle lever. In the event of a power failure in the aircraft, automatic reversion to the manual throttle control mode of operation is provided. The apparatus for achieving this consists of an outer housing shell having a lever arm extending radially therefrom, the outermost end of the lever arm being pinned to a source of translational motion such as provided by a push rod attached to the manual throttle lever. Within one end of the outer housing shell there is an output spool having on its outward facing end a boring sized to accommodate the throttle shaft of the engine fuel metering system. An input spool is mounted for rotation within the second end of the outer housing shell. The outward facing end of the input spool is secured by a shaft to the electronic fuel control equipment.

Abstract: A circuit protecting against overspeed and overheating in a two-cycle engine having a capacitive discharge ignition system which includes a charging coil in which voltage is induced when a magnet in the flywheel of the engine passes the coil. A rectifier bridge is connected to the coil and a capacitor connected to the bridge. An ignition coil and spark plug are associated with each cylinder of the engine. An electronic switch is associated with each ignition coil and has a trigger which responds to an applied trigger voltage to conduct and discharge the capacitor through the ignition coil. A trigger coil applies a trigger voltage to the triggers. The protective circuit includes a control responsive to engine speed. The control triggers one of the electronic switches to conduct and discharge the capacitor in response to a predetermined response speed. A circuit responsive to operation of an engine temperature responsive switch reduces the predetermined response speed of the control to a lower response speed.

Abstract: A system has an accelerator pedal switch for sensing the deceleration of a motor vehicle, an electronic circuit operative to cutoff fuel at deceleration of the motor vehicle in order to reduce fuel consumption of an engine. When the switch closes by the failure of the switch, the electronic circuit operates to continue the supply of fuel in order to prevent the stall of the engine.

Abstract: In order to detect cooling system malfunction, the operation of a pump which recycles the liquid coolant from a radiator (or condensor) to the coolant jacket of a vapor cooled type engine, is monitored. In the event that the pump operation period and frequency (viz., the time between changes in pump operation) fail to fall within a predetermined time schedule, a malfunction indicating signal is issued. The schedule can be varied in accordance with a signal indicative of the amount of fuel being combusted in the engine (viz., the amount of heat being produced by the engine) so as to take into the account the increased amount of coolant circulation which occurs under high engine load operation and the accompanying changes in pump operation characteristics.

Abstract: A novel oil addition device which is operable on vehicles frequently maintained in operational condition on unlevel surfaces for extended periods of time.

Abstract: A fuel injection timing control system of an internal combustion engine of a compression ignition type including a fuel injection pump driven by a cam connected to the engine, and a valve operative to return a part of the fuel delivered by the fuel injection pump to fuel source. The advance angle of the cam is set beforehand at a value bigger than those assumed in the range for normal operation, and the real fuel injection timing is modified by actuating the valve according to operating conditions of the engine.

Abstract: An operational condition control device for an internal combustion engine is provided which operates an alarm device when the engine temperature exceeds a predetermined temperature. The operational condition control device comprises a vehicle stop sensor for detecting a stopped condition of the vehicle, a temperature sensor for detecting the engine temperature, and a drive circuit for receiving signals from the sensors and operating the alarm device when the vehicle is in the stopped condition, and the engine temperature exceeds the predetermined temperature. In another aspect of the present invention, there is provided an operational condition control device for an internal combustion engine which operates a fuel cut device when the engine temperature exceeds a predetermined temperature and the vehicle is stopped to thereby stop the engine.

Abstract: In a method for electronically controlling the fuel supply to an internal combustion engine in response to operating conditions of the engine, fuel quantities are summed up, which are supplied to the engine after fulfillment of a predetermined condition for cutting off the fuel supply to the engine which is determined by engine operation parameters indicative of operating conditions of the engine, and when the sum of the fuel quantities exceeds a predetermined value, the fuel supply to the engine is cut off, thereby preventing deterioration of the driveability of the engine, burning of a catalyst provided in the engine for purifying exhaust gases, etc. at fuel cut operation of the engine.

Abstract: The invention provides a system applicable to various internal combustion engines, such as for automobiles, motorcycles, snowmobiles and outboards, to permit an authorized person, such as a police officer, to prevent their improper or illegal operation. The engine includes a detector detecting the speed of operation of the motor which is compared with a preset value. Upon an unusually high motor speed being reached a receiver is enabled for a preset period of time. During this preset period the engine can be disabled by a transmission from a transmitter operated by the police officer, preferably using a designated exclusive channel. The disabling slows the engine to an idle speed without stopping it, so that the power assist mechanisms of the vehicle remain operative to maintain normal braking and steering function.

Abstract: In a turbocharged engine, a pressure sensor is disposed downstream of the blower of the turbocharger and protective devices such as an alarm lamp for requiring the operator to lower the supercharging pressure and means for interrupting fuel feed to the engine are actuated under the control of a control circuit, when the supercharging pressure detected by the pressure sensor exceeds a preset maximum supercharging pressure. The control circuit does not permit the protective devices to operate unless the detected supercharging pressure continues higher than the preset maximum supercharging pressure for a predetermined time interval.