JP2014105820A - Vehicular control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate in advance a degree of smoking at an electrode of a spark plug before an internal combustion engine shows a poor starting in operation and restrict deterioration of smoking.SOLUTION: A degree of smoking at an electrode of a spark plug is evaluated on the basis of transition of an operation region of an internal combustion engine being operated. Then, a minimum value (a transmission line nearest to a high gear) of a transmission ratio of the transmission is updated in correspondence with the evaluation value. With this arrangement, the more a smoking at the electrode of the spark plug is accumulated, the more an engine speed is updated.

Description

  The present invention relates to a control device for a vehicle equipped with an internal combustion engine.

  When starting an internal combustion engine, it is usual to perform cranking by rotating a crankshaft of the engine by a starter motor (cell motor) which is an electric motor (for example, refer to the following patent document). Cranking ends when the engine starts from the first explosion to the consecutive explosion and the rotational speed of the crankshaft exceeds a determination value determined according to the coolant temperature or the like.

  If the internal combustion engine is operated only for a relatively short period of time in cold climates or winter environments, the temperature of the internal combustion engine does not rise sufficiently, so carbon is generated due to incomplete combustion, and the spark plug electrode A “smoldering” phenomenon that adheres to the surface occurs. Such smoldering lowers the insulation resistance between the center electrode and the ground electrode of the spark plug, causing ignition failure at the next start of the internal combustion engine. Furthermore, the unburned liquid fuel is adsorbed to the smoldering state, resulting in a “fogging” state in which the spark plug is sticky, and there is a possibility that the ignition and thus the start-up will become more difficult.

JP 2011-202643 A

  An object of the present invention is to preliminarily estimate the degree of smoldering of an electrode of a spark plug before the internal combustion engine falls into a starting failure and suppress deterioration of smoldering.

  In order to solve the above-described problems, in the present invention, the degree of smoldering of the electrode of the spark plug is estimated based on the transition of the operating region of the operating internal combustion engine, and the transmission of the transmission corresponding to the magnitude of the degree is estimated. The vehicle control device is characterized in that the minimum value of the gear ratio is changed.

  According to the present invention, the degree of smoldering of the electrode of the spark plug can be estimated in advance before the internal combustion engine falls into a starting failure, and deterioration of smoldering can be suppressed.

The figure which shows schematic structure of the internal combustion engine in one Embodiment of this invention. The figure which shows the structure of the drive system of the vehicle in the embodiment. The figure which illustrates the map of the index | exponent used for the calculation of the evaluation value which the control apparatus of the embodiment performs. The figure which shows the pattern of the control of the transmission which the control apparatus of the embodiment performs. The figure which shows the area | region of the water temperature at the time of a stop and the water temperature at the time of a start which correct | amend the evaluation value based on one modification of this invention.

  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 type four-stroke 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 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 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 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 gear 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 travel range, and a hydraulic pump (discharge fluid) supplied to the hydraulic servos 913 and 923 to operate the gear 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 (N signal) b output from an engine rotation sensor that detects the rotation angle of the crankshaft and the engine speed, An accelerator opening signal c output from a sensor that detects the amount of depression of the accelerator pedal or the opening of the throttle valve 32 as an accelerator opening (so-called required load), and a brake that is output from a sensor that detects the amount of depression of the brake pedal Stepping amount signal d, intake air temperature / intake pressure signal e output from a temperature / pressure sensor for detecting intake air temperature and intake pressure in intake passage 3 (especially surge tank 33), water temperature sensor for detecting engine cooling water temperature Output from the cam angle sensor at a plurality of cam angles of the cooling water temperature signal f output from the intake camshaft or exhaust camshaft. A cam angle signal (G signal) g is a sensor for to know the range of the shift lever (or, a shift position switch) shift range signal h or the like to be output from is input.

  From the output interface, an ignition signal i for the igniter 13 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 switching of connection / disconnection of the lockup clutch 73. An opening degree control signal l is outputted to the lockup solenoid valve, an opening degree control signal m is outputted to the solenoid valve for switching connection / disconnection of the forward brake 84 or the reverse clutch 85, a transmission ratio control signal n is outputted to the CVT 9, etc. .

  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, the intake air amount, and the like, various operating parameters such as required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, and ignition timing 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, and n corresponding to the operation parameters via the output interface.

  Further, the ECU 0 inputs a control signal o to an electric motor (starter motor or motor generator, not shown) when the internal combustion engine is started (it may be a cold start or a return from an idling stop). Then, cranking is performed by rotating the crankshaft by this electric motor. Cranking ends when the internal combustion engine starts from the first explosion to a continuous explosion and the engine speed, that is, the rotation speed of the crankshaft, exceeds a judgment value determined according to the cooling water temperature, etc. To do.

  The ECU 0 of the present embodiment quantitatively estimates the degree of smoldering of the electrode of the spark plug 12 based on the transition of the operating region of the internal combustion engine during operation.

  FIG. 3 shows the relationship between the operating range of the internal combustion engine and the likelihood of smoldering when carbon or the like adheres to the spark plug 12. In the present embodiment, the operation region is defined as [engine speed, load of internal combustion engine]. The load of the internal combustion engine corresponding to the vertical axis in FIG. 3 may be the accelerator opening, the intake pressure in the intake passage 3 (surge tank 33), the intake air amount filled in the cylinder 1 or the fuel injection. It may be an amount. Alternatively, it may be an engine torque output from the internal combustion engine.

  The curve drawn in FIG. 3 is an “isothermal line” where the temperature of the electrode of the spark plug 12 or a region in the vicinity thereof is constant. The numerical value (value size itself is only an example) entered in FIG. 3 is an index representing the degree of smoldering in the operating region. Smoldering such as carbon tends to occur when the temperature in the combustion chamber of the cylinder 1 is low and combustion is incomplete. Therefore, the lower the engine speed and the lower the load on the internal combustion engine, the larger the smoldering index.

  On the other hand, in an operating region where the engine speed and the engine load are relatively high, not only is smoldering difficult to occur, but smolder that has already adhered to the electrode of the spark plug 12 is also recombusted and removed. Therefore, the smoldering degree index has a negative value.

  ECU0 of this embodiment calculates | requires the evaluation value of the present degree of smoldering of the electrode of the spark plug 12 by integrating | accumulating the index | exponent according to a driving | operation area | region during the driving | operation of an internal combustion engine. More specifically, the map data that prescribes the relationship between the operating range of the internal combustion engine and the index of the likelihood of smoldering as shown in FIG. 3 is stored in the memory of the ECU 0 in advance. The ECU 0 searches the map using the current operation region of the internal combustion engine as a key, and reads an index corresponding to the current operation region. Then, by adding the index read from the map to the latest past evaluation value stored in the memory, a new evaluation value of the degree of smoldering at the present time is obtained.

  During the operation of the internal combustion engine, the ECU 0 calculates the evaluation value of the degree of smoldering of the electrode of the spark plug 12, that is, reads out the above index and adds it to the evaluation value at a constant time interval or a constant crank angle (CA). This is executed repeatedly for each crankshaft rotation angle. As a result, an evaluation value obtained by adding the index for each operation region multiplied by the length of the stay period in the operation region is obtained.

  When the internal combustion engine is stopped, the evaluation value immediately before the stop is stored in the memory of the ECU 0 and held. Then, after restarting the internal combustion engine, the calculation of the current evaluation value of the degree of smoldering of the electrode of the spark plug 12 is resumed from the evaluation value stored (held immediately before the previous stop) as the starting point.

  Note that when an operating region (high load and / or high rotation region) in which the temperature in the combustion chamber of the cylinder 1 is increased has passed, a negative index is added to the evaluation value. May decrease. However, the evaluation value shall be 0 as the minimum value and not a negative value.

  Thus, the ECU 0 of the present embodiment executes a process of changing the minimum value of the transmission ratio of the CVT 9 according to the evaluation value of the smoldering degree of the electrode of the spark plug 12.

  FIG. 4 is a shift diagram of the CVT 9. In FIG. 4, the solid line is a shift line when the transmission ratio of the CVT 9 is closest to the low gear. A broken line, a one-dot chain line, and a two-dot chain line are shift lines when the transmission ratio of the CVT 9 is closest to the high gear.

  A broken line is a shift line when the evaluation value of the degree of smoldering of the electrode of the spark plug 12 is 0 or less than a threshold value close to 0. The ECU 0 changes the shift line closest to the high gear in the low gear direction (direction in which the value of the gear ratio decreases) as the evaluation value for the degree of smoldering increases. That is, as the evaluation value for the degree of smoldering increases, the shift line closest to the high gear transitions upward in the figure from the chain line to the one-dot chain line, and further transitions to the two-dot chain line.

  Then, the transmission ratio of the CVT 9 while the vehicle is running is controlled. As described above, as the smoldering of the electrode of the spark plug 12 is accumulated, the engine speed is raised, so that a decrease in the temperature in the combustion chamber of the cylinder 1 and the temperature around the electrode of the spark plug 12 is suppressed. Occurrence is suppressed. Further, as the engine speed increases and the temperature in the combustion chamber of the cylinder 1 rises, the possibility that smoldering adhering to the electrode of the spark plug 12 will be removed increases.

  In the present embodiment, the degree of smoldering of the electrode of the spark plug 12 is estimated based on the transition of the operating region of the operating internal combustion engine, and the speed ratio of the transmissions 8 and 9 is determined according to the magnitude of the degree. The vehicle control device 0 is configured to change the minimum value (the shift line closest to the high gear).

  According to this embodiment, it is possible to evaluate the degree of smoldering of the electrodes of the spark plug 12 and suppress deterioration of smolding before the internal combustion engine falls into a starting failure. In addition, this contributes to an improvement in restartability of the internal combustion engine when the internal combustion engine is stopped at a low temperature in the previous operation.

  The present invention is not limited to the embodiment described in detail above. In the above embodiment, the minimum value of the transmission ratio of the transmissions 8 and 9 is changed according to the evaluation value of the degree of smoldering of the electrode of the spark plug 12, but in addition to this, during idling of the internal combustion engine The target idle speed in the feedback control of the engine speed may be changed. In that case, the target idle speed is set higher as the evaluation value of the smoldering degree of the electrode of the spark plug 12 is larger.

  Further, according to the evaluation value of the degree of smoldering of the electrode of the spark plug 12, the fuel injection amount at the time of restarting the internal combustion engine, the ignition timing, the number of times of spark ignition (a plurality of times in one expansion stroke of one cylinder 1) (A spark discharge is performed) may be changed.

  Smoldering of the electrode of the spark plug 12 is likely to occur due to a short trip operation in which the internal combustion engine is operated for a short period of time and stopped before the warm-up is completed. Therefore, the evaluation value of the degree of smoldering of the electrode of the spark plug 12 may be corrected according to the length of the operation period of the internal combustion engine.

  For example, the evaluation value immediately before the stop of the internal combustion engine or immediately after the restart is corrected according to the temperature level of the internal combustion engine before the stop of the previous operation. Here, “the previous stop of operation” means that the internal combustion engine has been stopped in principle in response to the ignition switch being turned OFF. An idle stop in a vehicle having an idle stop function does not correspond to a “previous operation stop”, but a stop of an internal combustion engine in a hybrid vehicle may correspond to a “previous operation stop”.

  The ECU 0 is an evaluation value of the degree of smoldering of the electrode of the spark plug 12 immediately before the stop of the internal combustion engine or immediately after the restart based on at least the temperature of the internal combustion engine at the time immediately before the internal combustion engine stops, that is, the coolant temperature of the engine. Correct. Then, the calculation processing of the current evaluation value (reading of the index shown in FIG. 3 and addition to the evaluation value) is resumed using the corrected evaluation value as a starting point.

  Basically, the evaluation value is increased as the coolant temperature immediately before the previous stop of the internal combustion engine is lower. Further, when the coolant temperature immediately before the previous stop is higher than a predetermined value, it is considered that the amount of smolder newly adhering to the electrode of the spark plug 12 is small, so there is no need to add correction to the evaluation value. .

  More specifically, each time the internal combustion engine is started, the ECU 0 stores and holds the cooling water temperature of the engine in the memory, and stores and holds the cooling water temperature of the engine in the memory every time the internal combustion engine is stopped.

Thereafter, the stop water temperature Tt stored at the time of the most recent stop of the internal combustion engine is the “previous stop water temperature Tt”, and the start-up water temperature Ts stored at the most recent start is the “previous start water temperature Ts ₀ ”. Respectively. In addition, the operation state in the period from the start to the stop of the latest internal combustion engine is referred to as “previous operation state”.

When the internal combustion engine is started, the previous stop water temperature Tt falls below the threshold value Thw, and the previous start water temperature Ts ₀ and the previous stop water temperature Tt are within a predetermined area A (hatched in FIG. 5). If this is the case, it is suggested that the previous operating state was not sufficiently warmed up. Region A is a region lower than the upper limit G0 of the previous stop water temperature Tt is determined depending on the starting temperature Ts ₀ last. The upper limit G0 is determined based on an experiment that observes the relationship between the starting water temperature Ts and the stopping water temperature Tt at which ignition failure due to smoldering or fogging of the spark plug 12 occurs.

The ECU _{0 determines} whether the internal combustion engine immediately before the stop of the internal combustion engine based on the temperature of the internal combustion engine at the start of the previous operation (previous start-up water temperature Ts ₀ ) and the temperature of the internal combustion engine before the stop (previous stop water temperature Tt) or The evaluation value of the degree of smoldering immediately after the restart is corrected. When the previous operation state is not within the region A shown in FIG. 5 (the previous stop water temperature Tt was higher than the predetermined value G0), or when the current start is a return from the idle stop, etc. Does not correct the smoldering evaluation value. In the case where the previous operation state is in the region A shown in FIG. 5, the smaller the previous stop water temperature Tt, the larger the correction amount is multiplied or added to the evaluation value of the smoldering degree.

  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 applied to control of a vehicle equipped with an internal combustion engine.

0 ... Control unit (ECU)
DESCRIPTION OF SYMBOLS 1 ... Cylinder 11 ... Injector 12 ... Spark plug 8, 9 ... Automatic transmission (forward / reverse switching device, CVT)

Claims (1)

The degree of smoldering of the electrode of the spark plug is estimated based on the transition of the operating region of the internal combustion engine that is operating, and the minimum value of the transmission gear ratio is changed in accordance with the degree of the degree. A vehicle control device.

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