JP5936123B2 - Internal combustion engine for vehicles - Google Patents

Description

  The present invention relates to a vehicular internal combustion engine characterized by control during idle operation.

  The internal combustion engine includes an alternator as an example of an auxiliary machine, and the alternator is driven by a crankshaft via a belt. The alternator is automatically driven according to the state of charge of the battery. Therefore, the alternator is often driven even during idle operation when the vehicle is stopped.

  In the case of a gasoline engine, the control of the output and the number of revolutions of the internal combustion engine is performed by the control of the throttle valve and the ignition timing control. In the control during the idle operation, for example, various loads on the engine (friction of the drive part) Friction torque such as resistance, alternator torque that is the load of the alternator, transmission torque that is the load of the automatic transmission, air conditioner torque that is the load of the compressor for the air conditioner, electric load torque that is the load of various electric devices) Calculate the ratio of these loads in advance as a map and perform feedback control to compare the torque generated by the actual rotation of the crankshaft and the ratio of various loads (torque) at any time to guide the rotation speed to the target value. Is going.

  In idle operation, it is necessary to maintain the rotation of the crankshaft while suppressing the amount of fuel used. However, if the load increases momentarily, engine stall may occur. In particular, since the load of the alternator is large, the engine stall during idling is mostly caused by the load of the alternator being applied to the crankshaft. In order to prevent engine stall even if the engine speed is reduced while the alternator is being driven, the engine speed is often set to a higher value so that the throttle valve against the load fluctuation of the alternator is often used. Due to the follow-up delay, there has been a case in which a phenomenon of blowing (or floating) in which the rotational speed increases rapidly occurs.

  In this regard, Patent Document 1 discloses that the amount of power generated by the alternator is detected and the ignition timing is advanced when the amount of power generated increases to prevent a decrease in the rotational speed.

JP-A-2-245436

  Since the ignition timing can be controlled instantaneously, the response of the crankshaft rotation up is much higher than the control of the throttle valve, and it can be said that Patent Document 1 is superior in this respect. However, since it cannot be said that the power generation amount of the alternator increases due to the decrease in rotation of the crankshaft, it can be said that it is very doubtful whether Patent Stall can prevent engine stall.

  In other words, to increase the amount of power generated by the alternator while the rotation of the crankshaft is decreasing, it means that the proportion of the torque generated by the crankshaft occupies the drive of the alternator increases. This means that a further load is applied to the engine. If the load further increases in a state where the rotation is reduced, the engine stall is likely to occur.

  More simply, in the state where the rotation of the crankshaft is decreasing, even if the power generation amount of the alternator is constant or decreased, the rotation of the crankshaft further decreases due to the load of the alternator. In other words, it can be said that a decrease in the rotation of the crankshaft often leads to a decrease in the amount of power generated by the alternator.

  In other words, since the alternator functions to maintain a predetermined power generation amount, when the rotation speed of the crankshaft decreases, the alternator acts to decrease the rotation of the crankshaft so as to maintain the predetermined power generation amount. The engine falls into a vicious circle where the engine speed decreases, and eventually the engine stalls.

  The present invention has been made in view of such a situation, and in common with Patent Document 1 that the rotation is recovered by the advance control of the ignition timing, but the event that triggers it is actually adapted. By doing so, it is intended to achieve accurate control.

  That is, the internal combustion engine of the present invention is configured such that the alternator is driven by the crankshaft, and the ignition timing is controlled so that the rotational speed is returned to the fluctuation before the fluctuation occurs at the time of idling operation. Control is performed so that the amount of adjustment of the ignition timing increases as the alternator load immediately before the occurrence of rotational fluctuation decreases.

  In this case, the rotation fluctuation of the crankshaft may be directly detected by a rotation sensor, the acceleration of the rotation of the crankshaft or a member linked to the crankshaft is detected by a sensor, and calculated from this, or the alternator duty ratio It is also possible to substitute by increasing the number. That is, the present invention includes a device that indirectly detects fluctuations in the rotational speed (rotational speed) of the crankshaft.

  If the rotation speed of the crankshaft decreases in the idle operation state, the rotation speed can be increased (returned to the original value) without engine stall by controlling the throttle valve if the decrease in the rotation speed is slow. If the pressure drops rapidly while a large load is applied, the rotational speed may not be recovered due to the control of the throttle valve, and the engine may stall as described above.

  Also, the alternator's operating rate during idle operation is not constant, and the battery's stored charge generates power with a high load or a low load depending on the usage status of the electrical equipment, etc., but the high load with a large alternator load Since the engine drive torque has sufficient capacity in the low speed range, there is time to restore it even if the engine speed decreases, but in the low load low speed range where the load on the alternator is small, the engine has no capacity. Since it is driven, if the rotation speed decreases for some reason, the rotation speed is likely to decrease at an accelerated rate because the alternator performs predetermined power generation.

  In this regard, in the present invention, since the alternator load is small, the amount of fluctuation of the ignition timing is increased based on the alternator load immediately before the rotational fluctuation occurs. Therefore, the rotational speed before the alternator load works to suppress the rotation. To prevent engine stall. Thereby, the reliability of the internal combustion engine (or vehicle) can be improved.

  Note that the adjustment amount of the ignition timing is also related to the rate of decrease in the rotational speed, and it is preferable to increase the advance amount of the ignition timing as the decrease in the rotational speed is larger (as the rate of decrease in rotational fluctuation is larger). Accordingly, the actual advance amount varies depending on the rate of decrease in the rotational speed, and even if the alternator is the same, the amount of fluctuation in the ignition timing may be different.

  Further, in the present invention, it is not always necessary to set the rotational speed of the idling operation to be high. For this reason, it is possible to prevent or suppress a decrease in blowup in which the rotational speed suddenly increases for some reason, thereby improving fuel efficiency. Can also contribute.

  Furthermore, the alternator varies in power generation capacity depending on the solid, and the power generation capacity usually decreases gradually during use, but the rotation speed caused by the load of the alternator in any rotation region of the crankshaft. It is also possible to memorize whether the reduction is likely to occur, and based on this memory, it is possible to modify the relationship map between the alternator duty ratio and the rotation speed, so that the optimum idle operation state suitable for each alternator Can be obtained.

It is a schematic diagram which shows embodiment of this invention. It is explanatory drawing of control. It is a flowchart which shows an example of control.

(1). Basic Configuration of Internal Combustion Engine Next, an embodiment of the present invention will be described based on the drawings. First, the basic configuration will be described. The basic structure of the internal combustion engine of the present embodiment is the same as that of the prior art, and includes a cylinder block 1 having a cylinder bore 2 as main elements, and a cylinder head that overlaps the cylinder block 1. Naturally, the piston 4 is slidably fitted in the cylinder bore 2, and the reciprocating motion of the piston 4 is converted into the rotation of the crankshaft 6 through the connecting rod 5.

  An intake passage 8 that is opened and closed by an intake valve 7 and an exhaust passage 10 that is opened and closed by an exhaust valve 9 are formed in the cylinder head 2, and an ignition plug 11 is provided in the center of the cylinder head 2. . An intake manifold 12 is connected to the intake passage 8, and an intake passage 13 is connected to the intake manifold 12. The intake path starts from an air cleaner 14, and an intercooler 15, a throttle valve 16, and a surge tank 17 are interposed in this order on the downstream side of the air cleaner 14.

  A fuel injection nozzle (injector) is provided in, for example, the surge tank 17 and the intake manifold in the intake passage 13, and the fuel injection amount is controlled by an instruction from the ECU 26. An exhaust manifold 18 is connected to the exhaust passage 10, and an exhaust passage 19 is connected to the exhaust manifold 18, and a part of the exhaust gas recirculates to the intake passage 13 via the EGR passage 20.

  A gear-shaped sensor plate 22 having a partially missing tooth is fixed to one end portion of the crankshaft 6, and the teeth of the sensor plate 22 are detected by the rotation sensor 23, and the detection time of adjacent teeth is detected. By calculating the interval, the rotational speed and the rotational speed (acceleration) can be obtained.

  An alternator 24 and a water pump 25 are attached to the cylinder block 1 as an example of an auxiliary machine, and the alternator 24 and the water pump 25 are driven by a drive pulley 26 and a belt 27 fixed to the crankshaft 6. Of course, the output line of the alternator 24 is connected to the battery 27, and power is supplied from the battery 27 to each part.

  The internal combustion engine has an ECU (engine control unit) 28 as a control means. The ECU 28 includes a pedal sensor 30 for detecting the amount of depression of the accelerator pedal 29, a vehicle speed sensor 31, the rotation sensor 23 described above, The alternator 24, the battery 27, the spark plug 11, and the throttle valve 18 are electrically connected. The arrow of the line connected to ECU28 has shown the direction of the signal.

(2). Idle operation control When the vehicle is stopped, the detection values of the pedal sensor 31 and the vehicle speed sensor 32 are zero. Therefore, when the pedal sensor 31 and the vehicle speed sensor 32 are maintained at the zero state for a predetermined time, it is recognized as an idle state, and the rotational speed of the crankshaft 6 is made to coincide with the target rotational speed based on the load map of the alternator 24 and the like. Feedback control is performed.

  In FIG. 2, R1 is a set target rotational speed, and R2 is a critical rotational speed that leads to engine stall. In FIG. 2, it is assumed that the actual rotational speed matches the target rotational speed R1. The actual rotational speed may decrease from the target rotational speed R1 due to slight disturbance of the intake air.

  In this case, when the alternator load is large, the engine has a surplus power even in a low speed range, so even if the rotational speed decreases from R1, a phenomenon occurs in which the rotational speed drops at an accelerated rate due to the load of the alternator 24. The smaller the alternator load, the more likely it is that the rotational speed decreases at an accelerated rate due to the load on the alternator 24.

  Further, when the speed reduction is slow as indicated by the dotted arrow A (when the gradient is gentle), the throttle valve 16 is opened to increase the fuel supply amount, so that the rotational speed before reaching the critical rotational speed R2 is reached. However, when the rotational speed is drastically decreased (when the gradient is steep) as indicated by the solid line B, the throttle valve 16 cannot be controlled and the rotational speed is decreased by the load of the alternator 24. As a result, the load on the alternator 24 increases (the duty ratio increases) due to a further decrease in the rotational speed.

  Therefore, as indicated by a one-dot chain line in FIG. 2 (B), a reduction rate slightly smaller than a reduction rate (gradient) that can barely increase the rotational speed by controlling the throttle valve 16 is set as a reference reduction rate (reference line) C. If it is set and the actual rotational speed reduction rate ΔR is in a rapid deceleration area where the reduction rate is larger than the reference reduction rate C, it is assumed that the duty ratio of the alternator 24 has increased, and the ignition timing is advanced. When the spark plug 11 is advanced, the throttle valve 16 is opened to increase the intake air when the actual rotational speed reduction rate ΔR is in the slow deceleration area smaller than the reference reduction rate C.

  Further, the alternator load immediately before the rotation fluctuation is read from the control map or the power generation amount, and the advance amount is controlled to be larger as the alternator load is smaller. That is, the advance amount is calculated using the reduction rate ΔR of the rotational speed as the first control factor, and further, the advance amount of the ignition timing is corrected using the alternator torque as the second control factor.

  Since the advance control of the ignition timing can be performed instantaneously, the crankshaft 6 can be returned to the safe target rotational speed R1 before falling to the dangerous rotational speed R2. It should be noted that when the rotational speed suddenly decreases, the throttle valve 16 can also be controlled in accordance with the ignition timing advance control. However, since there is a time lag in the rotational speed increase by the throttle valve 16, advance control There is little practical benefit in parallel with the opening operation of the throttle valve 16. Therefore, when the rotational speed reduction rate ΔR is higher than the reference reduction rate C, it is realistic to perform only the ignition timing advance control.

  The advance timing of the ignition timing may be approximately 1 to 3 degrees in terms of the rotation angle of the crankshaft 6, but more timely control is possible by associating so that the advance amount increases in proportion to the rate of decrease in the rotation speed. become.

  Although the rotation sensor 23 can detect a change in the rotation speed (speed change) of the crankshaft 6 in small increments, it may decelerate for a very short time and immediately return to the original rotation speed. Therefore, for example, if the deceleration tendency continues for several tens of degrees at the rotation angle of the crankshaft 6, it is determined that the vehicle is in the sudden deceleration area, and therefore advance angle control can be performed only when the decrease in the rotation speed becomes dangerous. .

  As shown in FIG. 2, when the rotation speed of the crankshaft 6 decreases, the duty ratio of the alternator 24 tends to increase from rank A to rank B. Therefore, the duty ratio of the alternator 24 is calculated from the electric power and the like. It is also possible to control the advance of the ignition timing using the rise of the engine as a trigger.

  FIG. 3 shows a control flowchart. This flow starts in the idling operation and the alternator 24 is driven. First, the level of the alternator load is repeatedly calculated at short time intervals from the control map or the detected power generation amount. The alternator load level is updated in a short time, and the latest level is determined to be held (S1). Next, it is determined at any time whether or not the rotational speed of the crankshaft 6 is decreasing at very short time intervals (S2).

  When the rotational speed continuously decreases for a predetermined time (or a predetermined angle), it is determined whether or not the reduction rate ΔR is larger than the reference value K (the slope of the line C in FIG. 2) (S3). When the value is larger than the reference value K, the advance amount of the ignition timing is calculated based on the magnitude of the reduction rate ΔR and the magnitude of the alternator load (S4), and the ignition is performed in a state advanced from the ignition plug 11 of the latest cylinder. (S5). When the alternator load is considerably large or when the rotational speed reduction rate ΔR is smaller than the reference value K, the routine proceeds to normal control using the throttle valve 16 (S6).

  After the ignition timing has been advanced, the difference between the actual rotational speed (rotational speed) of the crankshaft 6 and the target value is calculated by the comparison circuit (S7), and when the comparison value becomes zero, the original ignition is performed. Returning to the timing (S8), if the comparison value is negative, ignition in the advanced state is continued until the comparison value becomes zero.

  In this embodiment, the detection is performed using the detection value of the rotation sensor 23 for the advance angle control, and whether or not the value has returned to the normal value is also determined by the detection value of the rotation sensor 23. Since the rotation sensor 23 is originally provided in the internal combustion engine, it is not necessary to newly provide sensors. For this reason, an increase in cost can be prevented.

  The authorization of the alternator load level may be performed by actually detecting the actual power generation amount (voltage / current) of the alternator 24 or is instructed to the alternator 24 based on the amount of electricity stored in the battery 28 or the amount of electricity used. You may calculate from the electric power generation amount. The above explanation is a treatment when the rotational speed decreases, but the same applies when the rotational speed increases.

  The present invention can actually be applied to a vehicle internal combustion engine. Therefore, it can be used industrially.

DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Cylinder head 4 Piston 6 Crankshaft 11 Spark plug 13 Intake passage 16 Throttle valve 24 Alternator 28 Battery 29 ECU as control means

Claims (1)

The alternator is driven by the crankshaft, and the ignition timing is controlled so that the rotational speed is returned to the pre-fluctuation when a rotational fluctuation occurs during idle operation,
It is controlled so that the amount of adjustment of the ignition timing becomes larger as the alternator load just before the rotational fluctuation occurs is smaller.
Internal combustion engine for vehicles.

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