JP2014070592A - Control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a fail-safe internal combustion engine even when a failure occurs in a cooling system of a water-cooled internal combustion engine.SOLUTION: A control device: detects presence or absence of a failure in a cooling system which circulates cooling water to cool an internal combustion engine; limits output of the internal combustion engine to not more than predetermined output when an ability to circulate the cooling water is maintained but a failure occurs in the ability of a radiator to discharge heat; and sets an upper limit on engine torque in addition to limiting the output of the internal combustion engine to not more than the predetermined output when the failure occurs in the ability to circulate the cooling water.

Description

  The present invention relates to a control device that controls a vehicle equipped with an internal combustion engine and an automatic transmission.

  The mainstream of internal combustion engines for vehicles is a water-cooled type. In a water-cooled internal combustion engine, cooling water discharged from a water pump is circulated through a water jacket formed inside a cylinder block, a cylinder head or the like to cool various portions of the internal combustion engine. Then, after the cooling water is dissipated in the radiator, the cooling water is circulated such that the water pump sucks it and sends it again to the cylinder block or the like (for example, refer to the following patent document).

  The radiator is often accompanied by a fan for forced air cooling. When the cooling water in the radiator cannot be sufficiently cooled only by the driving air blown into the engine room when the vehicle is running, the radiator fan is rotated and blown toward the radiator to promote heat exchange between the cooling water and the outside air in the radiator To do.

  In such a cooling system, when the rotation of the radiator fan falls unsuccessfully or troubles in the circulation of the cooling water, the temperature of the internal combustion engine becomes extremely high, and abnormal combustion such as knocking frequently occurs in the cylinder, There is a risk of damaging the internal combustion engine.

JP 2012-102039 A

  An object of the present invention is to realize fail-safe when an abnormality occurs in a cooling system of a water-cooled internal combustion engine.

  In the present invention, the presence or absence of abnormality in the cooling system that circulates cooling water to cool the internal combustion engine is detected, and the cooling water circulation capability is maintained, but the heat dissipation capability in the radiator is impaired. In the case where the engine output is suppressed to a predetermined value or less and the cooling water circulation capability is impaired, in addition to suppressing the output of the internal combustion engine to a predetermined value or less, an upper limit is further set for the engine torque. The control device was configured.

  According to the present invention, it is possible to realize fail-safe when an abnormality occurs in the cooling system of a water-cooled internal combustion engine.

The figure which shows the whole structure of the internal combustion engine for vehicles in one Embodiment of this invention. The figure which shows the structure of the cooling system in the embodiment. The figure which shows the structure of the drive system in the embodiment. The flowchart which shows the example of the procedure of the process which the control apparatus of the embodiment performs. The figure which shows the content of control of the load and reduction ratio which the control apparatus of the embodiment implements. The figure which shows the content of control of the load and reduction ratio which the control apparatus of the embodiment implements.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment. The internal combustion engine in the present embodiment is a spark ignition gasoline engine and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives spark voltage generated by the ignition coil and causes spark discharge between the center electrode and the ground electrode. The ignition coil is integrally incorporated in a coil case together with an igniter that is a semiconductor switching element.

  The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream.

  The exhaust passage 4 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and an exhaust purification three-way catalyst 41 are disposed on the exhaust passage 4.

  FIG. 2 shows a cooling system for the internal combustion engine. A water jacket through which cooling water flows is formed inside the cylinder block 51 and the cylinder head 52 of the internal combustion engine. Outside the internal combustion engine, heat dissipating means 53 and 54 are provided for reducing the temperature of the cooling water that has been heated in the course of cooling the cylinder block 51 and the cylinder head 52. Examples of such heat radiating means include a heater 53 installed on the cabin side of the vehicle and a radiator 54 installed behind the front grille of the vehicle.

  A fan 55 is attached to the radiator 54. The radiator fan 55 is rotationally driven by an electric fan motor. The fan motor is supplied with electric power from an in-vehicle battery.

  The water pump 56 is a mechanical type that rotates by receiving a driving force transmitted from the crankshaft of the internal combustion engine. The water pump sucks the cooling water that has radiated heat in the heat radiating means 53 and 54 and has decreased in temperature, and sends the cooling water again toward the cylinder block.

  The electric power stored in the in-vehicle battery is generated by an alternator (not shown). As is well known, in an automobile, an alternator is rotated by utilizing a part of driving force output from an internal combustion engine, and the generated power is charged to a battery and supplied to various electric loads. In this embodiment, the same belt (or the pulley (or sprocket) fixed to the rotating shaft of the alternator, the pulley fixed to the rotating shaft of the water pump 56, and the pulley fixed to the crankshaft of the internal combustion engine are used. A winding transmission mechanism is configured by winding a chain. The rotational driving force output via the crankshaft is transmitted to each pulley via the belt, and further to the alternator and the water pump 56, respectively.

  The magnitude of the voltage generated and output by the alternator is controlled via a regulator. The regulator is a known IC type attached to the alternator. The power generation voltage of the alternator, that is, the voltage induced in the stator coil, increases in proportion to the DUTY ratio of the field current flowing through the field coil, that is, fDUTY. The regulator receives a signal o for instructing the generated voltage of the alternator from the ECU 0, and performs PWM control for adjusting fDUTY so as to realize the instructed generated voltage.

  FIG. 3 shows an example of a drive system provided in the vehicle. This drive system includes a torque converter 7 and automatic transmissions 8 and 9. In particular, in the present embodiment, a forward / reverse switching device 8 using a planetary gear mechanism and a belt-type CVT (Continuously Variable Transmission) 9 which is a type of continuously variable transmission are adopted as components of the automatic transmissions 8 and 9. doing.

  The rotational torque output from the internal combustion engine is input from the crankshaft of the internal combustion engine to the pump impeller 71 on the input side of the torque converter 7 and transmitted to the turbine runner 72 on the output side. The rotation of the turbine runner 72 is transmitted to the drive shaft 94 of the CVT 9 via the forward / reverse switching device 8 and rotates the driven shaft 95 through a shift in the CVT 9. The rotation of the driven shaft 95 is transmitted to the output gear 101. The output gear 101 meshes with the ring gear 102 of the differential device, and rotates the axle 103 and the drive wheels (not shown) via the differential device.

  The torque converter 7 includes a lockup mechanism. The lock-up mechanism is known in this field, and a lock-up clutch 73 that fastens the input side and the output side of the torque converter 7 so as not to rotate relative to each other, and an operation for switching the connection of the lock-up clutch 73. A lock-up solenoid valve (not shown) for controlling the hydraulic pressure (hydraulic pressure) is used as an element. The lockup solenoid valve is a flow rate control valve that receives a control signal l and changes its opening.

  In a vehicle equipped with CVT 9, when the vehicle speed is a predetermined value (for example, 10 km / h) or more, the torque converter 7 is almost always locked up. When the vehicle speed is equal to or lower than the predetermined value, the lockup of the torque converter 7 is released. During lockup, the lockup clutch 73 is pressed against the torque converter cover 74 and rotates together with the torque converter cover 74. In turn, the lock-up clutch 73 is separated from the torque converter cover 74 at the time of non-lock-up. At the time of non-lock-up, the engine torque input to the input side of the torque converter 7 is transmitted from the torque converter cover 74 to the pump impeller 71 and the turbine 72 and is transmitted to the forward / reverse switching device 8.

  In the forward / reverse switching device 8, the sun gear 81 communicates with the turbine runner 72, and the ring gear 82 communicates with the drive shaft 94. Between the planetary carrier 83 that supports the planetary gear 831 and the transmission case, a forward brake 84 that is a hydraulic clutch that can be connected and disconnected is interposed. Further, a reverse clutch 85, which is a hydraulic clutch capable of switching connection / disconnection, is also interposed between the planetary carrier 83 and the sun gear 81 (or the output side of the torque converter 7).

  In the D range of the traveling range, the forward brake 84 is engaged and the reverse clutch 85 is disconnected. As a result, the rotation of the output shaft of the torque converter 7 is reversed and decelerated and transmitted to the drive shaft 94 for forward travel. In turn, in the R range, the reverse clutch 85 is engaged and the forward brake 84 is disconnected. As a result, the sun gear 81 and the planetary carrier 83 rotate integrally, and the output shaft of the torque converter 7 and the drive shaft 94 are directly connected to perform reverse travel. A solenoid valve (not shown) that controls the hydraulic pressure for driving the forward brake 84 or the reverse clutch 85 to connect / disconnect is a flow rate control valve that receives a control signal m and changes its opening.

  In the N range and P range, which are non-traveling ranges, both the forward brake 84 and the reverse clutch 85 are disconnected.

  The CVT 9 includes a driving pulley 91 and a driven pulley 92, and a belt 93 wound around the pulleys 91 and 92 as elements. The drive pulley 91 is disposed behind the movable sheave 912, a fixed sheave 911 fixed to the drive shaft 94, a movable sheave 912 supported on the drive shaft 91 via a roller spline so as to be displaceable in the axial direction. A hydraulic servo 913 is provided, and the reduction ratio (transmission ratio) can be changed steplessly by operating the hydraulic servo 913 and displacing the movable sheave 912. The driven pulley 92 is disposed on the back of the movable sheave 922, a fixed sheave 921 fixed to the driven shaft 95, a movable sheave 922 supported on the driven shaft 95 via a roller spline so as to be axially displaceable. A hydraulic servo 923 is provided, and a belt thrust necessary for torque transmission is applied by operating the hydraulic servo 923 and displacing the movable sheave 922.

  A hydraulic pump (hydraulic fluid) supplied to the forward brake 84 or the reverse clutch 85 to operate the traveling range, and a hydraulic pump (which discharges hydraulic fluid supplied to the hydraulic servos 913 and 923 to operate the reduction ratio) (Not shown) is a known mechanical type (non-electric type) that operates by receiving torque transmitted from the crankshaft of the internal combustion engine. This hydraulic fluid is common to the fluid used for the torque converter 7.

  An ECU (Electronic Control Unit) 0 that is a control device of the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal b output from an engine rotation sensor that detects the rotation angle and engine speed of the crankshaft, and depression of an accelerator pedal. The accelerator opening signal c output from a sensor that detects the amount or the opening of the throttle valve 32 as an accelerator opening (so-called required load), the intake air temperature and the intake pressure in the intake passage 3 (particularly, the surge tank 33). Intake air temperature / intake pressure signal d output from the detected temperature / pressure sensor, cooling water temperature signal e output from the water temperature sensor detecting the cooling water temperature of the internal combustion engine, outside air temperature output from the temperature sensor detecting the outside air temperature Signal f, cam angle signal g output from the cam angle sensor at a plurality of cam angles of the intake camshaft or exhaust camshaft, vehicle Battery voltage indicating the state of charge of the battery, battery signal h or the like to be output from the sensor for detecting the battery current and the battery temperature are input.

  From the output interface, an ignition signal i for the igniter of the spark plug 12, a fuel injection signal j for the injector 11, an opening operation signal k for the throttle valve 32, and a lock for connection / disconnection switching of the lockup clutch 73. Opening control signal l for up solenoid valve, opening control signal m for solenoid valve for switching connection / disconnection of forward brake 84 or reverse clutch 85, reduction ratio control signal n for CVT9, and regulator for alternator On the other hand, a power generation voltage command signal o, a control signal p for switching ON / OFF of the radiator fan 55, and the like are output to a control circuit of a fan motor that drives the radiator fan 55.

  The processor of the ECU 0 interprets and executes a program stored in the memory in advance, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 0 acquires various information a, b, c, d, e, f, g, and h necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and is filled in the cylinder 1. Estimate the intake volume. Based on the engine speed and intake air amount, etc., the required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, ignition timing, and torque converter 7 lock-up are adjusted. Various operation parameters such as whether or not to perform the reduction, the reduction ratio of the automatic transmissions 8 and 9, the generated voltage of the alternator, and the ON / OFF of the radiator fan 55 are determined. As the operation parameter determination method itself, a known method can be adopted. The ECU 0 applies various control signals i, j, k, l, m, n, o, and p corresponding to the operation parameters via the output interface.

  The ECU 0 of the present embodiment detects the presence or absence of an abnormality in the cooling system that circulates the cooling water to cool the internal combustion engine, and if there is an abnormality in the cooling system, the throttle valve 32 is controlled according to the degree of the abnormality. Fail-safe control for correcting the opening degree (and fuel injection amount) and the reduction ratio of CVT 9 is executed.

The following two stages exist in the abnormality of the cooling system.
(I) The cooling water circulation capability is maintained, but the heat dissipation capability of the radiator 54 is impaired. The main causes include failure of the radiator fan 55 due to breakage of the radiator fan 55, damage to the fan motor, disconnection of a control circuit energizing the fan motor, and the like.
(Ii) Circulation capacity of cooling water is impaired. Causes include failure of the water pump 56, cutting of the belt (or chain) of the winding transmission mechanism that links the crankshaft and the water pump 56, detachment from the pulley (or sprocket), and circulating cooling water. Examples include clogging and breakage of a flow path such as a hose.

  Of course, (ii) is more severe and serious. In the case of (ii), there is a concern that the temperature suddenly rises around the portion around the cylinder 1 of the internal combustion engine, abnormal combustion such as knocking is caused in a short time, and the internal combustion engine is damaged.

  Compared with (ii), (i) is a situation in which some margin is still left. When the outside air temperature is low and the vehicle is running at a high speed, it is impossible to reduce the temperature of the cooling water in the radiator 54 only with the driving air blown into the engine room via the front grille. is not.

  FIG. 4 shows a procedure example of processing executed by the ECU 0 according to the program regarding the fail safe of the cooling system. The ECU 0 constantly monitors the cooling water temperature of the internal combustion engine, and when the cooling water temperature rises to a predetermined value or more (step S1), the radiator fan 55 is started (step S2). Promotes heat dissipation. When the cooling water temperature falls below a predetermined value (step S3), the rotation of the radiator fan 55 is stopped (step S4).

  The cooling water temperature does not fall below a predetermined value even after a predetermined time has elapsed since the radiator fan 55 was started, or the cooling water temperature further increased while the radiator fan 55 was rotating and exceeded the threshold value. In the case (step S5), it is determined that there is an abnormality in the cooling system.

  Then, it is determined whether the abnormal state of the cooling system is (i) or (ii) (step S6). As already described, in this embodiment, the same belt (or chain) is wound around the pulley (or sprocket) fixed to the rotating shaft of the water pump 56 and the pulley fixed to the rotating shaft of the alternator. The rotational driving force from the crankshaft is transmitted to the water pump 56 and the alternator. Therefore, when the water pump 56 is not properly driven to rotate, it is expected that the alternator is also not properly driven to rotate.

  Therefore, in step S6, the ECU 0 according to the present embodiment refers to the output voltage or battery current of the alternator, and an output voltage or battery current corresponding to the output voltage o currently commanded to the regulator of the alternator is generated. Whether or not the water pump 56 is properly driven to rotate is determined. If the output voltage or the battery voltage corresponding to the commanded output voltage o is generated, the alternator and the water pump 56 are properly driven to rotate, and there is no problem in the circulation of the cooling species, that is, (i) It is assumed that the situation is. Otherwise, it is presumed that the alternator and the water pump 56 are not properly driven to rotate, which hinders the circulation of the cooling species itself, that is, the situation (ii).

  If the situation is (i), the output of the internal combustion engine is suppressed to a predetermined value or less (step S7). Specifically, as shown in FIG. 5, the output of the internal combustion engine, which is the product of the engine speed and the engine torque, is suppressed below a predetermined line L1. Therefore, regardless of the amount of depression of the accelerator pedal operated by the driver, the opening of the throttle valve 32 (and the fuel injection amount) is reduced so as to satisfy the condition that the output is equal to or less than the line L1. Incidentally, what are indicated by thin broken lines in FIG. 5 are an equal intake amount line, an equal fuel injection amount line, and an equal heat generation amount line.

  In addition, the CVT 9 speed reduction ratio in a normal state where there is no abnormality in the cooling system is controlled along the shift line L2 in which the speed reduction ratio that provides the best fuel efficiency when various outputs are achieved. When there is an abnormality, not only the output is suppressed to the line L1 or lower, but also the reduction ratio of the CVT 9 may be controlled to the low gear side where the engine speed increases from the shift line L2. That is, the CVT 9 is operated so that the speed reduction ratio becomes larger than that of the shift line L2. This is intended to promote the temperature drop of the internal combustion engine while increasing the number of rotations of the water pump 56 linked to the crankshaft, increasing the circulating speed of the cooling water, and increasing the heat dissipation amount of the cooling water in the radiator 54 and the heater 53. is there. At the same time, the temperature increase in the local area of the internal combustion engine (particularly around the cylinder 1) is also dispersed throughout the engine.

  However, if the engine speed increases significantly, the temperature of the internal combustion engine will rise due to the increase in frictional heat. Therefore, as shown in FIG. 5, an upper limit L3 is set for the reduction ratio of CVT9. In general, in the situation of (i), the gear ratio of the CVT 9 is operated within the shaded range.

  When the situation is (ii), in addition to suppressing the output of the internal combustion engine below a predetermined value (step S8), the engine torque of the internal combustion engine is suppressed below a predetermined value (step S9). Specifically, as shown in FIG. 6, the output of the internal combustion engine is suppressed to a predetermined line L1 or lower, and the engine torque is suppressed to a predetermined line L4 or lower. Therefore, regardless of the amount of depression of the accelerator pedal operated by the driver, the opening degree of the throttle valve 32 (and the fuel injection amount) satisfies the condition that the output is below the line L1 and the engine torque is below the line L4. To lower.

  In particular, in a high load region where knocking is likely to occur even in normal times (the pressure in the surge tank 33 is high, the intake air amount and the fuel injection amount are large), abnormal combustion is almost certainly caused. In order not to make a transition to, the opening degree of the throttle valve 32 is sufficiently reduced, and the engine torque and the output are reduced as compared with the situation (i). In the situation (ii), the transmission ratio of the CVT 9 is operated within the range where the halftone dots are attached.

  In this embodiment, the presence or absence of abnormality in the cooling system that circulates cooling water to cool the internal combustion engine is detected, and the cooling water circulation capability is maintained, but the heat dissipation capability of the radiator 54 is impaired (i ), The output of the internal combustion engine is suppressed to a predetermined L1 or less, and when the circulation capacity of the cooling water is impaired (ii), in addition to suppressing the output of the internal combustion engine to a predetermined L1 or less, The control device 0 is characterized in that an upper limit L4 is set for the engine torque.

  According to the present embodiment, it is possible to realize fail-safe when an abnormality occurs in the cooling system of the water-cooled internal combustion engine. That is, by reducing the amount of heat generated by the internal combustion engine and suppressing the temperature increase of the internal combustion engine, the vehicle can be operated for a certain period even in a situation where the water cooling function of the internal combustion engine is reduced. The driver can evacuate to a place where the vehicle can be repaired (such as a dealer) or a safe place (such as an emergency parking zone on a highway) during that period.

  The present invention is not limited to the embodiment described in detail above. In the above embodiment, in step S6, the remaining capacity of the water pump 56 is estimated based on the power generation amount of the alternator, and it is determined whether the situation is (i) or (ii). As a mode of the present invention, the change in the temperature rise of the cooling water temperature of the internal combustion engine is compared with the change in the operation range of the internal combustion engine [engine speed, load (or intake pressure, intake amount, fuel injection amount)]. If the cooling water temperature has risen abruptly so as not to match the transition of (i), it may be determined as (ii), otherwise (i). In determining whether the situation is (i) or (ii) based on the rate of temperature rise of the cooling water temperature, it is preferable to also consider the value of the outside air temperature.

  If a flow rate sensor that measures the flow rate of the cooling water circulating in the cooling system is mounted in the cooling system, the flow rate of the cooling water is detected via the flow rate sensor, and whether the situation is (i) (ii) ).

  If the water pump 56 is an electric pump, whether or not the water pump 56 is operating properly by referring to the voltage applied to the pump motor that rotationally drives the water pump 56 and the armature current. That is, it can be determined whether the situation is (i) or (ii). A diagnosis function originally associated with the electric water pump 56 may be used.

  In addition, the specific configuration of each unit, the processing procedure, and the like can be variously modified without departing from the spirit of the present invention.

  The present invention can be used as a fail safe for a cooling system of an internal combustion engine mounted on a vehicle.

0 ... Control unit (ECU)
32 ... Throttle valve 54 ... Radiator 55 ... Radiator fan 56 ... Water pump 8,9 ... Automatic transmission (forward / reverse switching device, CVT)

Claims (1)

Detects whether there is an abnormality in the cooling system that circulates cooling water to cool the internal combustion engine,
If the cooling water circulation capability is maintained but the heat dissipation capability of the radiator is impaired, the output of the internal combustion engine is suppressed to a predetermined level or less,
A control device characterized by further setting an upper limit on the engine torque in addition to suppressing the output of the internal combustion engine to a predetermined value or less when the cooling water circulation capability is impaired.

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