Abstract: An atmosphere learning device performs atmosphere learning upon an output value from an oxygen concentration sensor based on the output value from the sensor when an exhaust passage is in an atmospheric state. The device includes a stop request determination device, an opening-closing valve control device, and a learning execution device. The stop request determination device is for determining whether an operation stop request of an engine has been made. The opening-closing valve control device is for controlling an opening-closing valve into a predetermined valve-opening state when it is determined by the determination device that the operation stop request has been made. The learning execution device is for executing the atmosphere learning after control of the opening-closing valve into the predetermined valve-opening state by the control device.

Abstract: A rotational phase difference of a camshaft relative to a crankshaft in a variable valve timing mechanism is controlled by an operation of an oil control valve. That is, in the oil control valve, there is outputted an operational signal which is defined by adding a feedback correction amount corresponding to a difference between an actual value and a target value of the rotational phase difference, to a holding learning value as the operational signal for holding the rotational phase difference. The holding learning value is altered only by a specified value on condition that the operational signal for holding the rotational phase difference is assumed to change.

Abstract: A rotational phase difference of a camshaft relative to a crankshaft in a variable valve timing mechanism is controlled by an operation of an oil control valve. That is, in the oil control valve, there is outputted an operational signal which is defined by adding a feedback correction amount corresponding to a difference between an actual value and a target value of the rotational phase difference, to a holding learning value as the operational signal for holding the rotational phase difference. The holding learning value is altered only by a specified value on condition that the operational signal for holding the rotational phase difference is assumed to change.

Abstract: An ECU computes a guard value K and limits an amount of change in a measured atmospheric pressure value of an atmospheric pressure sensor per unit time through use of the computed guard value. The guard value is a value that corresponds to an amount of change in the atmospheric pressure per unit time caused by a change in an altitude.

Abstract: An ECU computes a guard value K and limits an amount of change in a measured atmospheric pressure value of an atmospheric pressure sensor per unit time through use of the computed guard value. The guard value is a value that corresponds to an amount of change in the atmospheric pressure per unit time caused by a change in an altitude.

Abstract: The present invention provides a method for displaying an operation status of a construction machine by sensing operating information of the construction machine by means of a coolant water sensor and the like, sending the operating information to a control computer while the control computer receives the operating information which has been sent from the construction machine, determines whether the construction machine is in operation or not based on the received operating information, and displays the result of judgment on a monitor screen, so that the current operation status of the construction machine can be known easily.

Abstract: At a time point at which an ignition switch is made OFF and an engine is stopped, an output of a downstream gas sensor is read, thereafter, at a time point at which a predetermined time period has elapsed from stopping the engine, the output of the downstream gas sensor changed by flowing the atmosphere back into an exhaust pipe is read. Thereafter, a change in the output of the downstream gas sensor until the predetermined time period has elapsed from stopping the engine is calculated, the change in the output is compared with an abnormality determinant and when the change in the output is smaller than the abnormality determinant, response of the downstream gas sensor is determined to be abnormal.

Abstract: An anti-theft system for construction machines, comprising a memory which stores, as machine-side identification information, first identification information allocated construction machine by construction machine and second identification information allocated in common to plural construction machines, a first collating medium having the same identification information as the first identification information, a second collating medium having the same identification information as the second identification information, a collator which collates the identification information of the first or the second collating medium with the machine-side identification information, and an operation controller which cancels the inhibit of operation of the construction machine concerned when there is obtained a coincident collation result by the collator. With this anti-theft system, an owner of construction machines can manage the construction machines by only one type of a collating medium while preventing theft.

Abstract: An anti-theft system for construction machines, comprising a memory which stores, as machine-side identification information, first identification information allocated construction machine by construction machine and second identification information allocated in common to plural construction machines, a first collating medium having the same identification information as the first identification information, a second collating medium having the same identification information as the second identification information, a collator which collates the identification information of the first or the second collating medium with the machine-side identification information, and an operation controller which cancels the inhibit of operation of the construction machine concerned when there is obtained a coincident collation result by the collator. With this anti-theft system, an owner of construction machines can manage the construction machines by only one type of a collating medium while preventing theft.

Abstract: At a time point at which an ignition switch is made OFF and an engine is stopped, an output of a downstream gas sensor is read, thereafter, at a time point at which a predetermined time period has elapsed from stopping the engine, the output of the downstream gas sensor changed by flowing the atmosphere back into an exhaust pipe is read. Thereafter, a change in the output of the downstream gas sensor until the predetermined time period has elapsed from stopping the engine is calculated, the change in the output is compared with an abnormality determinant and when the change in the output is smaller than the abnormality determinant, response of the downstream gas sensor is determined to be abnormal.

Abstract: A control circuit for a construction machine using a control lever for revolving a boom swing in common with a traveling motor and switching pilot pressure via a switching valve has a switch for supplying a switching signal to the switching valve. A pressure switch detects whether the pilot pressure is output from a remote control valve or not. A switching control circuit switches a position of the switching valve to a position for the boom swing cylinder when the switching signal is output from the switch and holds the position of the switch at the position for the boom swing cylinder when the pilot pressure is detected by the pressure switch, to thereby prevent wrong operation in switching.

Abstract: It is determined whether the current operation condition is in a transitional or steady state. If the operation condition is in a transitional state, then the transition gain is obtained by multiplying the transition base gain that is calculated corresponding to engine speed with a map by a transition degree correction coefficient. If the operation condition is in a steady state, the steady-state gain is set to the steady-state gain that is calculated corresponding to the engine speed. Subsequently, the control magnitude OCVC of the oil pressure control valve is obtained by multiplying the difference between the target advance angle and the actual advance angle by the gain.

Abstract: The present invention is a control circuit for a construction machine for using a control lever for revolving and boom swing in common and switching pilot pressure via a switching valve, comprising: a switch for supplying a switching signal to the switching valve; a pressure switch for detecting whether the pilot pressure is output from a remote control valve or not; a switching control circuit for switching a position of switch to a position for a boom swing cylinder when the switching signal is output from the switch and holding the position of switch at the position for the boom swing cylinder when the pilot pressure is detected by the pressure switch, to thereby prevent wrong operation in switching.

Abstract: The present invention provides a method for displaying an operation status of a construction machine by sensing operating information of the construction machine by means of a coolant water sensor and the like, sending the operating information to a control computer while the control computer receives the operating information which has been sent from the construction machine, determines whether the construction machine is in operation or not based on the received operating information, and displays the result of judgment on a monitor screen, so that the current operation status of the construction machine can be known easily.

Abstract: It is determined whether the current operation condition is in a transitional or steady state. If the operation condition is in a transitional state, then the transition gain is obtained by multiplying the transition base gain that is calculated corresponding to engine speed with a map by a transition degree correction coefficient. If the operation condition is in a steady state, the steady-state gain is set to the steady-state gain that is calculated corresponding to the engine speed. Subsequently, the control magnitude OCVC of the oil pressure control valve is obtained by multiplying the difference between the target advance angle and the actual advance angle by the gain.

Abstract: An air/fuel ratio controller/method learns the deviation from a target air/fuel ratio and stores that learned value in a backup memory except when engine compartment temperature is ecessive.

Abstract: To control the air-fuel ratio of an internal combustion engine without variations and thus suppress deterioration of the exhaust gas, a canister for adsorbing evaporated fuel is connected to a fuel tank. A release passage connects the canister to an intake tube for an internal combustion engine. A purge duty cycle flow rate control valve is installed in this release passage. An ECU provides feedback control of the air-fuel ratio according to the oxygen concentration in exhaust gas, controls the idle speed via an ISC valve, and controls purge by the purge duty cycle vacuum switching valve. As the purge is carried out, evaporated gas is released from the canister and purged. The ECU makes a decision, in a non-purging mode, as to whether the amount of the purged gas reaches a purge limit that is a critical value tolerated at each instant of time. If the result is that the purge limit will be reached, the execution of the purge is inhibited.

Abstract: A valve timing control apparatus for an internal combustion engine includes a variable valve timing control mechanism of a hydraulic type which is provided in a drive force transmission arrangement for transmitting a drive force from a driving shaft to a driven shaft for actuating one of an engine-cylinder inlet valve and an engine-cylinder outlet valve, and which can relatively rotate one of the driving shaft and the driven shaft in a predetermined angular range. A detecting device operates for detecting a condition in which air enters hydraulic working fluid in the variable valve timing control mechanism. A trouble diagnosis device operates for implementing a trouble diagnosis on the variable valve timing control mechanism. An inhibiting device operates for inhibiting the trouble diagnosis implemented by the trouble diagnosis device when the detecting device detects the condition in which air enters hydraulic working fluid in the variable valve timing control mechanism.

Abstract: A valve timing control apparatus for an internal combustion engine includes a variable valve timing control mechanism of a hydraulic type which is provided in a drive force transmission arrangement for transmitting a drive force from a driving shaft to a driven shaft for actuating one of an engine-cylinder inlet valve and an engine-cylinder outlet valve, and which can relatively rotate one of the driving shaft and the driven shaft in a predetermined angular range. A detecting device operates for detecting a condition in which air enters hydraulic working fluid in the variable valve timing control mechanism. A trouble diagnosis device operates for implementing a trouble diagnosis on the variable valve timing control mechanism. An inhibiting device operates for inhibiting the trouble diagnosis implemented by the trouble diagnosis device when the detecting device detects the condition in which air enters hydraulic working fluid in the variable valve timing control mechanism.

Abstract: When fuel supply system abnormality diagnosis conditions are satisfied, the abnormality of a fuel supply system is diagnosed by comparing an air/fuel ratio deviation index value with a lean/rich abnormality determination value by diagnosis means. At this time, a hot lean abnormality determination value KHL is set leaner than an ordinary lean abnormality determination value KLL, and a hot rich abnormality determination value KHH is set richer than an ordinary rich abnormality determination value KLH by abnormality determination value setting means when the engine compartment temperature is high. As a result, it is possible to diagnose whether or not the fuel supply system is abnormal (i.e., an abnormal deviation in the air/fuel ratio) while preventing the mistake even when the engine compartment temperature is high, so that the early discovery of the abnormality and the prevention of the mistaken diagnosis are made compatible.