JP2016028908A - Hybrid electric vehicle control unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device capable of smoothly accelerating a hybrid electric vehicle at a time of acceleration at which the rising of an engine torque is delayed due to a delay in the introduction of EGR gas into a combustion chamber.SOLUTION: A hybrid electric vehicle control device comprises: connecting-disconnecting means (52) connecting or disconnecting an engine (1) to or from a motor-generator (51); an EGR device (14) opening an LP-EGR valve (17) in a predetermined LP-EGR region to supply EGR gas to a combustion chamber (7); torque assist means (55) instructing the connecting-disconnecting means (52) to connect the motor-generator (51) to the engine (1), and causing the motor-generator (51) to assist the engine (1) in an engine torque generated by the engine (1) in response to an intake pipe volume that the engine (1) has to range from the LP-EGR valve (17) to an inlet of the combustion chamber (7).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for a hybrid vehicle, and particularly to a device equipped with an LP-EGR device.

  When the speed of changing the opening of the EGR valve or the speed of changing the opening of the throttle valve is larger than a predetermined value during transient operation, there is a technique that decreases the engine torque request change amount by increasing the assist torque or regenerative torque by the motor generator. (See Patent Document 1). This is for engines equipped with HP-EGR devices. Then, it is determined that the in-cylinder EGR ratio cannot be accurately controlled when each of the opening change speeds is excessively large, and the engine torque request change amount is decreased when each of the change speeds is greater than a predetermined value. The in-cylinder EGR ratio during transient operation is controlled with high accuracy.

JP 2010-167838 A

  By the way, in an engine equipped with an LP-EGR device, there is a delay until the EGR gas actually flows into the combustion chamber when the operating point shifts from the non-LP-EGR region to the LP-EGR region due to acceleration. Particularly in a gasoline engine, the basic ignition timing is set in the LP-EGR region according to the target LP-EGR ratio. For this reason, during acceleration when the operating point shifts from the non-LP-EGR region to the LP-EGR region, the actual LP-EGR ratio becomes smaller than the target LP-EGR ratio while the supply of EGR gas to the combustion chamber is delayed. . Thus, knocking is likely to occur at the basic ignition timing corresponding to the target LP-EGR ratio. Then, since feedback control of the ignition timing for avoiding knocking is performed, the ignition timing is retarded. As a result, the actual engine torque falls below the target engine torque in the early stage of acceleration, and the feeling of acceleration becomes insufficient, and the desired feeling of acceleration cannot be obtained.

  Similarly, when the operating point shifts from the LP-EGR region to the non-LP-EGR region, there is a delay until the flow of EGR gas into the combustion chamber stops. Since the amount of fresh air cannot be reduced while the flow of EGR gas into the combustion chamber does not stop, the actual engine torque exceeds the target engine torque and is not decelerated, and the desired deceleration feeling cannot be obtained.

  In this case, in an engine provided with the LP-EGR device, the influence of each opening degree changing speed on the engine torque is small. For this reason, the technique of the said patent document 1 currently applied to the engine provided with an HP-EGR apparatus cannot be applied as it is to an engine provided with an LP-EGR apparatus.

  Therefore, the present invention can perform smooth acceleration / deceleration at the time of acceleration in which the rise of the engine torque is delayed with the delay in introduction of EGR gas into the combustion chamber or at the time of deceleration at which the engine torque is insufficient with a delay in introduction and stop of EGR gas. An object is to provide an apparatus.

  A hybrid vehicle control device according to the present invention is a hybrid vehicle control device using an engine and a motor generator as drive sources, and includes connection / disconnection means, an LP-EGR device, and torque assist means. The connection / disconnection means connects / disconnects the engine and the motor generator. The LP-EGR device opens the LP-EGR valve in a predetermined LP-EGR region and supplies EGR gas to the combustion chamber. The torque assist means instructs the connection / disconnection means to connect the motor generator and the engine during acceleration accompanied by an increase in the target EGR ratio. Further, the motor generator assists the engine torque generated by the engine according to the intake pipe volume. The torque assist means instructs the connection / disconnection means to connect the motor generator and the engine at the time of deceleration accompanied by a decrease in the target EGR ratio. Furthermore, according to the intake pipe volume, the motor generator is generated with the engine torque generated by the engine to regenerate electric power. Here, the intake pipe volume is an intake pipe volume of the engine and is an intake pipe volume from the LP-EGR valve to the combustion chamber inlet.

  According to the present invention, at the time of acceleration in which the engine torque rises with a delay in the introduction of EGR gas, smooth acceleration can be performed without the torque rise delay. Further, when the engine torque becomes excessive due to the delay in stopping the EGR gas, the excessive torque can be eliminated and smooth deceleration can be performed.

1 is a schematic configuration diagram of a hybrid vehicle according to a first embodiment of the present invention. It is a driving | operation area | region figure which shows a supercharging area | region and LP-EGR area | region. It is a characteristic view of a target EGR ratio. It is a timing chart which shows the change of the engine torque at the time of acceleration when an operating point shifts from a non-LP-EGR field to a LP-EGR field. It is a timing chart which shows the change of the engine torque and the amount of assist torque at the time of acceleration when an operating point shifts from a non-LP-EGR area to an LP-EGR area. It is a flowchart for demonstrating calculation of the assist torque amount command value given to a motor generator, and ON / OFF control of an electromagnetic clutch. It is a characteristic view of the amount of assist torque. It is a flowchart for demonstrating calculation of the electric power regeneration amount command value given to a motor generator, and ON / OFF control of an electromagnetic clutch. It is a characteristic view of electric power regeneration amount. It is a flowchart for demonstrating calculation of an ignition timing command value. It is a characteristic view of basic ignition timing. It is a characteristic view of an actual EGR ratio. It is a characteristic view of difference EGR ratio correction amount. It is a characteristic view of the exhaust gas temperature correction amount.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic configuration diagram of a control device for a hybrid vehicle 50 using a gasoline engine and a motor generator as drive sources according to a first embodiment of the present invention.

  The vehicle 50 has an engine 1 and a motor generator 51. The engine 1 and the motor generator 51 are drive sources for the vehicle 50. The output shaft of the engine 1 and the motor generator 51 are connected via an electromagnetic clutch 52. Here, the electromagnetic clutch 52 is disconnected when the electromagnetic solenoid 53 is not energized. When the electromagnetic clutch 52 is disengaged, the engine 1 and the motor generator 51 are not connected. On the other hand, when the electromagnetic solenoid 53 is energized, the electromagnetic clutch 52 is connected. When the electromagnetic clutch 52 is in the connected state, the engine 1 and the motor generator 51 are connected. A battery 54 is electrically connected to the motor generator 51.

  The engine 1 is a gasoline engine (hereinafter also simply referred to as “engine”). The engine 1 includes an intake passage 4 and an exhaust passage 11. The intake passage 4 includes an intake pipe 4a, an intake collector 4b, and an intake manifold 4c.

  The intake pipe 4a immediately upstream of the intake collector 4b is provided with an electronically controlled throttle device that responds to the amount of depression of the accelerator pedal. The throttle device includes a throttle valve 5 and a motor (rotary electric machine) 6 that drives the throttle valve 5. The intake air is metered by the throttle valve 5 through the intake pipe 4a. The metered air is stored in the intake collector 4b, and is distributed and supplied from the intake collector 4b to the cylinders 7 (combustion chambers) of the respective cylinders via the intake manifold 4c. Although the embodiment is an electronically controlled throttle device, the throttle valve and the accelerator pedal may be connected by a wire.

  A fuel injection valve 8 is provided on the intake manifold 4c and a spark plug 9 is provided directly on the cylinder 7, and fuel is injected from the fuel injection valve 8 into the intake manifold 4c (intake port). The injected fuel is mixed with air metered by the throttle valve 5 to form a gas, which is ignited by the spark plug 9 and burned. The burning gas is discharged into the exhaust passage 11 after performing the work of pushing down the piston 10. The position where the fuel injection valve 8 is provided is not limited to the intake manifold. A fuel injection valve may be provided directly facing the cylinder 7.

  The exhaust passage 11 includes an exhaust manifold 11a into which exhaust from the cylinder 7 of each cylinder flows, and an exhaust pipe 11b connected to a collective portion of the exhaust manifold 11a. Since the exhaust contains harmful three components of HC, CO, and NOx, a manifold catalyst 12 is provided at the assembly portion of the exhaust manifold 11a and a main catalyst 13 is provided at the exhaust pipe 11b downstream of the exhaust manifold 11a in order to purify all of them. Yes. The main catalyst 13 is provided, for example, under the floor of the vehicle. Each of these catalysts 12 and 13 is composed of, for example, a three-way catalyst. A muffler 19 is provided at the end of the exhaust pipe 11b.

  The engine 1 further includes a turbocharger 21. The turbocharger 21 includes a turbine 22 provided in the exhaust pipe 11b, a compressor 23 provided in the intake pipe 4a, and a shaft 24 connecting the turbine 22 and the compressor 23. The turbine 22 is rotated by the energy of the exhaust gas flowing through the exhaust pipe 11b, and drives the compressor 23 coaxial with the turbine 22. The compressor 23 compresses the air sucked through the air cleaner 18. The compressed air that is compressed and exceeds the atmospheric pressure is sent to the intake collector 4b. The target supercharging pressure can be obtained by operating the turbocharger 21.

  The turbocharger 21 includes a bypass passage 24 that bypasses the turbine 22 and a normally closed waste gate valve 25 that opens and closes the bypass passage 24. The waste gate valve 25 is driven by a motor (rotating electric machine) 26. For example, when the actual boost pressure detected by the boost pressure sensor 45 becomes higher than the target boost pressure, the waste gate valve 25 is opened by driving the motor 26 and a part of the exhaust flowing into the turbine 22 is removed. The turbine 22 is bypassed to flow. As a result, the turbine rotational speed is decreased from before the waste gate valve 25 is opened, and the compressor rotational speed coaxial with the turbine 22 is also decreased. When the compressor rotational speed decreases, the actual supercharging pressure decreases and matches the target supercharging pressure. The opening degree of the waste gate valve 25 is held at a timing at which the actual boost pressure coincides with the target boost pressure.

  An intercooler 25 is provided in the intake pipe 4 a on the downstream side of the compressor 23. The intercooler 25 is for cooling the air compressed by the compressor 23. The air whose temperature has been increased by the air compression by the compressor 23 is cooled by the intercooler 25, whereby the supercharging efficiency can be increased.

  Now, even in the gasoline engine 1 provided with the turbocharger 21, there is a demand to perform a large amount of EGR (exhaust gas recirculation) in order to suppress knocking in the supercharging region. In order to meet this requirement, in this embodiment, a ropeless loop EGR device 14 is newly provided. The rope pressure loop EGR device 14 includes an EGR passage 15, an EGR cooler 16 interposed in the EGR passage 15, an EGR valve 17 (for example, a butterfly valve) that opens and closes the EGR passage 15, and a motor (rotary electric machine) that drives the EGR valve 17. 18.

  The EGR passage 15 is branched from the exhaust pipe downstream of the turbine 22, specifically, the exhaust pipe 11 b between the manifold catalyst 12 and the main catalyst 13, and merges with the intake pipe 4 a upstream of the compressor 23. Thus, when the EGR passage 15 communicates the exhaust pipe 11b downstream of the turbine 22 and the intake pipe 4a upstream of the compressor 23, the gas is determined by the differential pressure between the exhaust pipe pressure downstream of the turbine and the intake pipe pressure upstream of the compressor. (A part of the exhaust gas) flows through the EGR valve 17. Since the differential pressure between the exhaust pipe pressure downstream of the turbine and the intake pipe pressure upstream of the compressor is as small as about 1 kPa, for example, it is called a ropeless loop EGR (hereinafter referred to as “LP-EGR”) device. Hereinafter, the EGR valve of the LP-EGR device is referred to as “LP-EGR valve”. Further, an operation region in which the LP-EGR valve 17 is opened and LP-EGR is performed is referred to as an “LP-EGR region”, and an operation region in which the LP-EGR valve is fully closed is referred to as a “non-LP-EGR region”. The LP-EGR device itself is known in diesel engines, but in the present embodiment, the LP-EGR device 14 is newly adopted for the gasoline engine 1 provided with the turbocharger 21.

  The EGR cooler 16 is provided in the EGR passage 15 upstream of the LP-EGR valve 17. The EGR cooler 16 cools the gas (a part of the exhaust gas) flowing through the EGR passage 15 until it reaches a certain temperature. For this reason, in the LP-EGR region, the gas cooled to a certain temperature flows through the LP-EGR valve 17.

  Here, the reason why the LP-EGR device 14 is newly adopted in the gasoline engine 1 provided with the turbocharger 21 will be described. There is an EGR device that is applied to a gasoline engine that does not include a turbocharger and that causes a portion of relatively high-temperature exhaust to flow into the intake collector 4b. In this EGR device, gas flows through the LP-EGR valve with a relatively large differential pressure (negative pressure) between the exhaust passage 11 and the intake collector 4b, so that a high pressure loop EGR (hereinafter referred to as “HP-EGR”) device. Called.

  Consider applying the HP-EGR device to a gasoline engine equipped with a turbocharger. First, when not supercharging, a pressure (negative pressure) lower than the atmospheric pressure develops in the intake collector 4b, and the differential pressure from the exhaust pressure becomes large. Therefore, if the LP-EGR valve is opened, gas (EGR gas) is taken in. It can be sucked into the collector 4b. However, at the start of supercharging by the turbocharger, the pressure of the intake collector 4b increases from negative pressure to atmospheric pressure and from atmospheric pressure to a pressure exceeding atmospheric pressure. When the pressure of the intake collector 4b increases to a pressure exceeding the atmospheric pressure, the differential pressure from the exhaust pressure decreases. The pressure exceeding the atmospheric pressure in the intake collector 4b is a supercharging pressure. The higher the supercharging pressure, the smaller the differential pressure from the exhaust pressure. When the differential pressure from the exhaust pressure becomes small, a large amount of EGR gas cannot be sucked into the intake collector 4b.

  On the other hand, in the LP-EGR device, gas (EGR gas) flows through the LP-EGR valve 17 with a small differential pressure (about 1 kPa) between the relatively low exhaust pipe pressure downstream of the turbine and the intake pipe pressure upstream of the compressor. It is not affected by supercharging pressure. In other words, a configuration in which the LP-EGR device 14 is added to the gasoline engine 1 provided with the turbocharger 21 allows a large amount of EGR gas to be introduced into the intake passage even during supercharging by the turbocharger 21. It became.

  More specifically, FIG. 2 shows the supercharging region and the LP-EGR region of this embodiment in an overlapping manner. In FIG. 2, the case where the pressure of the intake collector 4b is atmospheric pressure is indicated by a broken line. In the present embodiment, a region where the pressure of the intake collector 4b is higher than the atmospheric pressure (region above the broken line) is a supercharging region, and a region where the pressure of the intake collector 4b is equal to or lower than the atmospheric pressure (region below the broken line) is not. It is a supercharged area. On the other hand, the LP-EGR region has a substantially isosceles trapezoidal shape as a whole, and the LP-EGR region is largely generated in the supercharging region in this embodiment.

  For this reason, in this embodiment, the operation region is divided into four regions as follows.

<1> Supercharging region and LP-EGR region (region surrounded by B-C-D-E)
<2> Supercharging region and non-LP-EGR region (region indicated by hatching)
<3> Non-supercharging region and LP-EGR region (region surrounded by ABEF)
<4> Non-supercharging range and non-LP-EGR range

  Here, in FIG. 2, the corners of the isosceles trapezoid are A, C, D, and F, and the points where the isosceles trapezoid and the broken line intersect are B and E. Further, both ends of the broken line are G and J, and the GH-I line is a line at full load. Note that the LP-EGR region is not limited to a substantially isosceles trapezoidal shape as a whole. If the specifications of the engine, turbocharger, and LP-EGR device 14 are different, the shape of the LP-EGR region may be different.

  As shown in FIG. 1, the present embodiment further includes a bypass passage 31 that bypasses the compressor 23. The bypass passage 31 is provided with a recirculation valve 32 driven by a motor (rotating electric machine) 33. This valve 32 recirculates (recirculates) pressurized air confined in the intake pipe 4a from the throttle valve 5 to the compressor 23 upstream of the compressor 23 when the throttle valve 5 is closed for vehicle deceleration. It is for making it happen. On the other hand, when turbocharging is performed by the turbocharger 21 in an operating region other than when the vehicle is decelerating, the valve 32 is basically fully closed and air upstream of the compressor 23 (including EGR gas). ) Are all guided to the compressor 23.

  Here, the reason why the recirculation valve 32 is necessary is that the handling of the throttle valve differs between the diesel engine and the gasoline engine. That is, in a diesel engine, the throttle valve is always open and is closed only when necessary. On the other hand, in a gasoline engine, the throttle valve 5 is provided immediately upstream of the intake collector 4b, and its opening changes in response to the amount of depression of the accelerator pedal.

  Due to such a difference, in the gasoline engine, when the accelerator pedal is returned to decelerate the vehicle from the state of being supercharged by the turbocharger 21, the throttle valve opening is increased by a certain amount in response to this. Become smaller. Due to this sudden decrease in the throttle valve opening, there is no place for the pressurized air existing in the intake pipe 4 a from the throttle valve 5 to the compressor 23. In addition, the pressure of the intake pipe 4a from the throttle valve 5 to the compressor 23 further increases due to the operation of the compressor 23 when the vehicle is decelerated. Then, the air whose pressure is increased downstream of the compressor flows backward toward the compressor 23. Then, when the pressurized air that flows backward passes through the compressor 23 and escapes upstream, noise (noise) is generated from the compressor 23. Such noise generated during vehicle deceleration affects the quietness of the vehicle compartment. Therefore, when the vehicle is decelerated from the supercharging region, the valve 32 is switched from the fully closed state to the open state, and the pressurized air upstream of the compressor is bypassed the compressor 23 and released upstream (recirculation). This prevents the generation of noise during vehicle deceleration.

  Next, if the EGR ratio when performing LP-EGR control using the LP-EGR device 14 is referred to as “EGR ratio”, the target value of the EGR ratio in the combustion chamber (this target value is hereinafter referred to as “target EGR ratio”). ) Map characteristics are as shown in Fig. 3. That is, as shown in Fig. 3, the substantially isosceles trapezoidal LP-EGR region is roughly divided into two, and the region on the high load side is 0. .1 and 0.2 in the low load region.

  The reason why the target EGR ratio is made smaller in the high load side region than in the low load side region is as follows. That is, if the fresh air can be pushed into the cylinder 7 on the high load side by the turbocharger, the target EGR ratio can be set to 0.2 on the high load side as well as on the low load side. However, even if fresh air is actually pushed into the cylinder 7 by the turbocharger, the amount of fresh air that can be pushed is limited. On the other hand, it is necessary to generate a larger engine torque on the high load side than on the low load side. Therefore, by reducing the target EGR ratio in the range where knocking does not occur on the high load side and in the range where the knocking does not occur, and improving the combustion state in the cylinder 7 by that amount, a larger engine torque than on the low load side can be obtained. It is to be obtained. In FIG. 3, the target EGR ratio is set in two stages, but the present invention is not limited to the case where the target EGR ratio is set in two stages. The target EGR ratio may be changed in three or more stages or continuously.

  Next, it is necessary to determine the LP-EGR valve opening so that the target EGR ratio is obtained. Here, in this embodiment, the EGR ratio is a value defined by the following equation.

EGR ratio = LP-EGR valve flow rate / (fresh air amount + LP-EGR valve flow rate)
... (1)
The new air amount in the equation (1) is the amount of air detected by the air flow meter 42, and the LP-EGR valve flow rate in the equation (1) is the amount of gas flowing through the LP-EGR valve 17. The LP-EGR valve flow rate is determined by the LP-EGR valve front-rear differential pressure and the LP-EGR valve opening area Segr.

  In this case, although the generation of NOx is suppressed by the introduction of EGR gas into the combustion chamber 7 in the LP-EGR region, the combustion state cannot be deteriorated as compared with the state where no EGR gas is introduced. Absent. Therefore, the engine controller 41 sets the basic ignition timing ADV0 in accordance with the target EGR ratio in the LP-EGR region. For example, the basic ignition timing ADV0 is advanced as the target EGR ratio increases. In this case, the basic ignition timing ADV0 is set so that MBT (Minimum advance for Best Torque) can be obtained even when the EGR gas having the target EGR ratio is introduced into the combustion chamber 7. Therefore, in the normal LP-EGR region, good fuel efficiency can be obtained by the basic ignition timing ADV0 while suppressing the generation of NOx. On the other hand, even in the non-LP-EGR region (that is, a state where EGR gas is not introduced into the combustion chamber 7), the engine controller 41 sets the basic ignition timing ADV0 according to the engine operating conditions so as to obtain MBT. Yes.

  Further, the engine controller 41 feedback-controls the ignition timing based on a signal from the knock sensor 47 in order to prevent knocking in the non-LP-EGR region. For example, the average value of the knock signal from the knock sensor 47 is compared with a predetermined slice level S / L. When the average value of the knock signal exceeds the slice level S / L, it is determined that knocking has occurred, and the ignition timing is retarded stepwise by a constant value ΔE. This avoids knocking. The average value of the knock signal from the knock sensor 47 is compared with a predetermined slice level at regular intervals, and if the average value of the knock signal is equal to or lower than the slice level S / L, it is determined that knocking has not occurred. The ignition timing is now advanced by a constant value ΔF. Here, the fixed value ΔF is set to a value smaller than the fixed value ΔE. As described above, when knocking occurs, the angle is retarded by a predetermined value in a stepwise manner, and when knocking does not occur thereafter, the ignition timing is gradually advanced. When knocking occurs, the operation of retarding the ignition timing step by step by a certain value ΔE is repeated. As a result, the ignition timing is kept at the basic ignition timing ADV0 as much as possible while avoiding knocking.

  Now, it is assumed that the accelerator pedal is depressed to accelerate the hybrid vehicle 50, and the engine operating point shifts from the non-LP-EGR region to the LP-EGR region by this acceleration. Even if the LP-EGR valve 17 is opened with good response at this transition timing, EGR gas is not immediately introduced into the combustion chamber 7 at the transition timing from the non-LP-EGR region to the LP-EGR region. Even if the LP-EGR valve 17 is opened so that the target EGR ratio can be obtained immediately at the transition timing, it takes time until the EGR gas is actually introduced into the combustion chamber 7 from the transition timing (the response delay is Because). That is, until the EGR gas is actually introduced into the combustion chamber 7 from the transition timing, the actual value of the EGR ratio in the combustion chamber (this actual value is hereinafter referred to as “actual EGR ratio”) becomes smaller than the target EGR ratio. .

  As described above, during the transition period in which the actual EGR ratio is smaller than the target EGR ratio, the basic ignition timing ADV0 is excessively advanced and knocking occurs. This knocking is detected by a knock sensor 47. Then, in response to the occurrence of knocking detected by the knock sensor 47, the feedback amount FB of the ignition timing is calculated, and the ignition timing is retarded by this feedback amount FB. When the ignition timing is retarded, the engine torque decreases accordingly, so that the actual engine torque falls below the target engine torque at the beginning of acceleration when shifting from the non-LP-EGR region to the LP-EGR region, resulting in insufficient acceleration. The desired acceleration feeling cannot be obtained.

  On the other hand, the same problem also occurs when the hybrid vehicle 50 is decelerated by returning the accelerator pedal and the engine operating point shifts from the LP-EGR region to the non-LP-EGR region by this deceleration. That is, the introduction of EGR gas into the EGR combustion chamber 7 does not end immediately at the transition timing from the LP-EGR region to the non-LP-EGR region. Even if the LP-EGR valve 17 is immediately switched to the fully closed state at the transition timing, it takes time until the introduction of the EGR gas into the combustion chamber 7 actually ends from the transition timing (there is a response delay). Because. That is, the actual EGR ratio becomes larger than the target EGR ratio until the introduction of the EGR gas into the combustion chamber 7 actually ends from the transition timing. As described above, during the transition period in which the actual EGR ratio is larger than the target EGR ratio, the fresh air amount cannot be reduced. Therefore, the actual engine torque does not exceed the target engine torque and is not decelerated. A feeling of deceleration cannot be obtained.

  As described above, in the gasoline engine, the engine torque is insufficient and the target engine torque cannot be obtained at the time of acceleration when shifting from the non-LP-EGR region to the LP-EGR region. Further, there is a problem that the engine torque becomes excessive and the target engine torque cannot be obtained at the time of deceleration from the LP-EGR region to the non-LP-EGR region.

  The acceleration will be further described with reference to FIG. FIG. 4 shows how the engine torque changes when the engine operating point shifts from the non-LP-EGR region to the LP-EGR region when acceleration is performed by depressing a certain amount of accelerator pedal at the timing of t1. Is shown. In FIG. 4, the solid line represents the case of an engine that does not include the LP-EGR device. However, in order to compare with the case of the engine provided with the LP-EGR device as in this embodiment, the engine having the same performance is used. In the case of an engine that does not have an LP-EGR device, it is not affected by EGR gas, so that the engine torque quickly rises from the timing of t1, and the target engine torque (desired acceleration feeling) can be obtained from the early stage of acceleration. It becomes.

  On the other hand, the broken line in FIG. 4 is for the engine where the operating point shifts from the non-LP-EGR region to the LP-EGR region when acceleration is performed by depressing a certain amount of accelerator pedal at the timing of t1. In the case of this engine, in the LP-EGR region, the amount of fresh air in the combustion chamber 7 is reduced by the amount of EGR gas and the engine torque is reduced. Therefore, the compression ratio may be increased by the amount of EGR gas. . When the compression ratio is increased, knocking is likely to occur. Therefore, the basic ignition timing ADV0 is set to be retarded by the increase in the compression ratio. Nevertheless, during the transient period in which the actual EGR ratio is smaller than the target EGR ratio as described above, the basic ignition timing ADV0 is excessively advanced and knocking occurs. This knocking is detected by a knock sensor 47, and the ignition timing is retarded. When the ignition timing is retarded, the engine torque is reduced accordingly, so that the actual engine torque is lower than the target engine torque particularly in the early stage of acceleration (deviation is greater than the solid line). In the initial stage of acceleration, the actual engine torque falls below the target engine torque, resulting in a lack of acceleration, and the desired acceleration feeling cannot be obtained.

  In FIG. 4, the alternate long and short dash line is an improvement of the engine having the broken line characteristics. That is, this is a case of an improved engine in which the EGR ratio is slightly smaller than the target EGR ratio with respect to the engine having the broken line characteristics, and the waste gate valve 25 is controlled to be closed on the side where the boost pressure is increased. Even if the engine is improved in this way, the engine torque still decreases in the initial stage of acceleration as in the broken line. Thus, it can be seen that the temporary decrease in the engine torque at the initial stage of acceleration cannot be eliminated simply by making improvements to the engine.

  In order to solve this problem, the following comparative example has been disclosed on the premise of a hybrid vehicle using an engine equipped with an HP-EGR device and a motor generator as a drive source. That is, in this comparative example, when the opening change speed of the LP-EGR valve or the opening change speed of the throttle valve is larger than a predetermined value during a transition, the engine torque request change is increased by increasing the assist torque or regenerative torque by the motor generator. The amount is decreasing.

  However, in the case of the engine 1 provided with the LP-EGR device 14 as in the present embodiment, unlike the engine provided with the HP-EGR device, the opening change speed of the LP-EGR valve 17 and the opening of the throttle valve 5 are different. The influence of the speed change speed on the engine torque is small. For this reason, in the case of the engine 1 including the LP-EGR device 14, even if the assist torque amount is determined according to the opening change speed of the LP-EGR valve 17 or the opening change speed of the throttle valve 5, the engine torque is changed. The effect to give is small.

  Therefore, in the first embodiment of the present invention, the engine 1 is generated by the motor generator 51 according to the volume of the intake pipe when the motor controller 55 is accelerating the hybrid vehicle 50 and accelerating with an increase in the target EGR ratio. Assist engine torque. Further, when the hybrid vehicle 50 is decelerated and the motor controller 55 decelerates with a decrease in the target EGR ratio, the motor generator 51 generates electric power with the engine torque generated by the engine 1 according to the volume of the intake pipe and regenerates electric power. . Since there is a limit to the improvement of the engine, torque assist / power regeneration means (55) is used, and at the time of acceleration accompanied by an increase in the target EGR ratio, the motor generator 51 assists the engine torque, so that the target engine is started from the initial stage of acceleration. Torque is obtained. Further, the target engine torque can be obtained from the initial stage of deceleration by using the torque assist / power regeneration means (55) and generating power by generating the motor generator 51 with the engine torque at the time of deceleration accompanied by a decrease in the target EGR ratio. To. Here, the “intake pipe volume” is the intake pipe volume of the engine 1 and the intake pipe volume from the position where the LP-EGR valve 17 is attached to the inlet of the combustion chamber 7. Hereinafter, the intake pipe volume of the engine 1 and from the attachment position of the LP-EGR valve 17 to the inlet of the combustion chamber 7 is also simply referred to as “intake pipe volume of the engine 1”.

  The reason why the motor generator 51 assists the engine torque or generates power according to the intake pipe volume of the engine 1 during the transition of the hybrid vehicle 50 (acceleration and deceleration) is as follows. That is, in the engine 1 provided with the LP-EGR device 14, the introduction start delay of EGR gas generated at the time of acceleration when the operating point shifts from the non-LP-EGR region to the LP-EGR region is much higher than that of the engine provided with the HP-EGR device. Big. In addition, the EGR gas introduction / stop delay that occurs during deceleration when the operating point shifts from the LP-EGR region to the non-LP-EGR region is significantly greater than that of an engine that includes the HP-EGR device. That is, it is the intake pipe volume of the engine 1 that greatly affects the EGR gas introduction start delay that occurs during acceleration when the operating point shifts from the non-LP-EGR region to the LP-EGR region. In addition, the intake pipe volume of the engine 1 greatly affects the delay in introducing and stopping EGR gas that occurs during deceleration when the operating point shifts from the LP-EGR region to the non-LP-EGR region. As the intake pipe volume increases, the introduction start delay of EGR gas that occurs during acceleration when the operating point shifts from the non-LP-EGR region to the LP-EGR region increases. In addition, as the intake pipe volume increases, the delay in introducing and stopping EGR gas that occurs during deceleration when the operating point shifts from the LP-EGR region to the non-LP-EGR region increases. Therefore, the motor generator 51 assists the engine torque or generates power according to the intake pipe volume of the engine 1 to regenerate power.

  As a result, the acceleration of the transition from the non-LP-EGR region to the LP-EGR region is eliminated, and the engine torque that is caused by the delay in starting the introduction of EGR gas into the combustion chamber 7 is eliminated, and smooth acceleration is performed from the beginning of acceleration. Can be made. On the other hand, at the time of deceleration that shifts from the LP-EGR region to the non-LP-EGR region, it is possible to eliminate the engine torque excessively while delaying the introduction and stop of EGR gas into the combustion chamber 7 and to perform smooth deceleration.

  This will be further described with reference to FIG. The upper part of FIG. 5 is a model of how the engine torque rises due to the difference in the intake pipe volume of the engine 1 when the operating point shifts from the non-LP-EGR region to the LP-EGR region due to acceleration. Is shown. For reference, what happens in the case of an engine that does not include an LP-EGR device is indicated by a solid line in the upper part of FIG. The lower part of FIG. 5 shows a model of how the assist torque amount by the motor generator 51 changes due to the difference in the intake pipe volume of the engine 1. Here, for simplification, the change in the engine torque shown in the upper part of FIG. 5 and the change in the assist torque amount shown in the lower part of FIG. 5 are divided into the cases of three engines of large, medium, and small intake pipes. Show.

  As indicated by the broken line in the upper part of FIG. 5, when the operating point shifts from the non-LP-EGR region to the LP-EGR region, the engine torque increases as the intake pipe volume of the engine 1 becomes small, medium, and large. Will be delayed. This is because the start delay of introduction of EGR gas into the combustion chamber 7 increases as the engine has a larger intake pipe volume. In accordance with the rising of the engine torque corresponding to the small, medium and large intake pipe volumes, as shown by the broken line in the lower part of FIG. Compensate for engine torque rise delay. At that time, the engine with the intake pipe volume being small, medium, and large is matched with the delay in the rise of the engine torque. That is, as the intake pipe volume is small, medium, and large, the assist torque amount by the motor generator 51 is increased to small, medium, and large. As a result, the total torque of the engine torque and the assist torque rises from the initial stage of acceleration in the same way as the solid-line engine torque, regardless of whether the intake pipe volume is small, medium, or large. To do.

  In this embodiment, the acceleration point when the operating point shifts from the non-LP-EGR region to the LP-EGR region and the deceleration time when the operating point shifts from the LP-EGR region to the non-LP-EGR region are mainly handled. However, this is not the only case. For example, unlike FIG. 3, it is assumed that the target EGR ratio is set so as to increase as the load increases in the LP-EGR region. At this time, when the target EGR ratio shifts from a small side to a large side by acceleration within the LP-EGR region, the actual EGR ratio becomes smaller than the target EGR ratio due to a delay in increasing the EGR gas to the combustion chamber 7. . If knocking occurs due to this, the ignition timing is retarded, which causes a problem that the target engine torque cannot be obtained. Therefore, when the target EGR ratio is set so as to increase toward the higher load side in the LP-EGR region, the main EGR ratio is also increased when shifting from a smaller side to a larger side by acceleration in the LP-EGR region. The subject of the invention.

  Further, unlike FIG. 3, it is assumed that the target EGR ratio is set to be smaller as the load becomes lower in the LP-EGR region. At this time, when the target EGR ratio shifts from the larger side to the smaller side due to deceleration within the LP-EGR region, the actual EGR ratio deviates from the target EGR ratio due to the delay in reducing the EGR gas. Along with the delay in reducing the EGR gas, there is a problem that the actual engine torque exceeds the target engine torque and the target engine torque cannot be obtained. Accordingly, when the target EGR ratio is set to be smaller in the LP-EGR region as the load is lower, the target EGR ratio is shifted from the larger side to the smaller side by deceleration in the LP-EGR region. The subject of the present invention.

As shown in FIG. 1, in addition to the fuel injection valve 8 and the spark plug 9, an engine controller 41 is provided to control the LP-EGR valve 17, the waste gate valve 25, and the recirculation valve 32. The engine controller 41 is configured as a computer unit including peripheral devices such as a microprocessor, ROM, and RAM. The engine controller 41 receives signals from an air flow meter 42, an accelerator sensor 43, a crank angle sensor 44, an O2 concentration sensor 45, an exhaust temperature sensor 46, and a knock sensor 47. Here, the air flow meter 42 detects the amount of air (fresh air amount) flowing into the intake pipe 4a. The accelerator sensor 43 detects the amount of accelerator pedal depression (accelerator opening) and the amount of change. The crank angle sensor 44 detects the engine rotation speed. The O ₂ concentration sensor 45 detects the O ₂ concentration in the intake pipe from the downstream of the compressor 23 to the inlet of the combustion chamber 7. The exhaust temperature sensor 46 detects the exhaust temperature Texh. The knock sensor 47 detects knocking that occurs in the combustion chamber 7.

  The engine controller 41 calculates a basic ignition timing ADV0 at which MBT is obtained according to the engine operating point determined from the engine load and the rotational speed Ne in the LP-EGR region and the target EGR ratio. In the non-LP-EGR region, the basic ignition timing ADV0 at which MBT is obtained is calculated according to the engine operating point determined from the engine load and the rotational speed Ne. When knocking occurs in the non-LP-EGR region, knocking is avoided by feedback control of the ignition timing.

  Further, the engine controller 41 estimates an actual EGR ratio in the LP-EGR region, and calculates a difference EGR ratio ΔR that is a difference between the target EGR ratio and the actual EGR ratio. Then, a difference EGR ratio correction amount HOS1 (first ignition timing correction amount) corresponding to the difference EGR ratio ΔR is calculated so that the actual EGR ratio matches the target EGR ratio, and the basic ignition timing is calculated based on the difference EGR ratio correction amount HOS1. ADV0 is corrected. This is because the actual EGR ratio becomes smaller than the target EGR ratio for a while after the transition when the operating point shifts from the non-LP-EGR region to the LP-EGR region. That is, when the actual EGR ratio is smaller than the target EGR ratio for a while after the transition to the LP-EGR region, the combustion state of the working gas in the combustion chamber 7 is improved and knocking is likely to occur. This is to avoid this. In terms of engine control, the actual EGR ratio may be larger than the target EGR ratio within the LP-EGR region. In this case, the combustion state of the working gas in the combustion chamber 7 is deteriorated by the difference, and the engine becomes unstable. In order to avoid this, the ignition timing is corrected with the differential EGR ratio correction amount HOS1. .

  Further, in the engine controller 41, when the exhaust temperature Texh detected by the exhaust temperature sensor 46 deviates from a predetermined set temperature Tset, an exhaust temperature correction amount HOS2 (second ignition according to the temperature difference from the set temperature Tset). (Time correction amount) is calculated. Then, the basic ignition timing ADV0 is corrected by the exhaust temperature correction amount HOS2. This is because, even when the operating point shifts from the non-LP-EGR region to the LP-EGR region at the same acceleration, when the exhaust temperature Texh is different from the set temperature Tset, the amount of EGR gas introduced into the combustion chamber 7 is This is to cope with this because it changes. That is, even at the same acceleration when shifting to the LP-EGR region, when the exhaust gas temperature Texh is lower than the set temperature Tset, the exhaust gas pressure decreases, and the amount of EGR gas that passes through the LP-EGR valve 17 (and therefore into the combustion chamber 7). The amount of EGR gas introduced is reduced. This is because knocking may occur when the amount of EGR gas introduced into the combustion chamber 7 decreases, and this is avoided. In terms of engine control, it is conceivable that the exhaust temperature Texh is higher than the set temperature Tset in the LP-EGR region even during the same acceleration when shifting to the LP-EGR region. In this case, the exhaust pressure increases, the amount of EGR gas passing through the LP-EGR valve 17 (and hence the amount of EGR gas introduced into the combustion chamber 7) increases, and combustion becomes unstable. The ignition timing is corrected by the exhaust gas temperature correction amount HOS2.

  In addition, a motor controller 55 is provided to control the motor generator 51 and the electromagnetic clutch 52. The motor controller 55 is also configured as a computer unit including peripheral devices such as a microprocessor, ROM, and RAM. The motor controller 55 and the engine controller 41 are connected via a CAN communication device 56. The motor controller 54 controls ON / OFF of the electromagnetic clutch 52 and the amount of assist torque generated by the motor generator 51.

  Control performed by the motor controller 55 and the engine controller 41 will be described with reference to the following flowchart.

  First, the flowcharts of FIGS. 6 and 8 are used to calculate the assist torque amount command value Tast and the power regeneration amount command value Tkis that the motor controller 55 gives to the motor generator 51, and to control ON / OFF of the electromagnetic clutch 52. It is. Among these, the flow of FIG. 6 is for calculating the assist torque amount command value at the time of acceleration when the operating point shifts from the non-LP-EGR region to the LP-EGR region. On the other hand, the flow of FIG. 8 is for calculating a power regeneration amount command value during deceleration when the operating point shifts from the LP-EGR region to the non-LP-EGR region. 6 and 8 are executed at regular time intervals (for example, every 10 ms).

  The flow of FIG. 6 will be described. In step 1, it is determined whether or not the engine operating point is in the LP-EGR region shown in FIG. When the operating point is in the LP-EGR region, the process proceeds to step 2. In step 2, it is checked whether or not the acceleration flag (initially set to zero when the engine is started) = 1. Here, the process proceeds to step 3 assuming that the acceleration flag = 0.

  In step 3, an accelerator opening change amount per predetermined time (hereinafter simply referred to as “accelerator opening change amount”) ΔAPO is calculated based on the accelerator opening APO detected by the accelerator sensor 43. The accelerator opening APO is sent from the engine controller 41 to the motor controller 55 via the CAN communication device 56.

  For example, the accelerator opening change amount ΔAPO is calculated by subtracting the accelerator opening before a predetermined time from the current accelerator opening, that is, the following expression.

ΔAPO = APO−APOz (2)
Where APOz: accelerator opening before a predetermined time,
ΔAPO in equation (1) is a positive value during acceleration and a negative value during deceleration.

  In step 4, the absolute value | ΔAPO | of the accelerator opening change amount is compared with a predetermined value A. The predetermined value A is set in advance as a value for determining whether or not it is a transition time (acceleration and deceleration). When the absolute value | ΔAPO | of the accelerator opening change amount exceeds the predetermined value A, it is determined that the engine is in transition, and the process proceeds to Step 5.

  In step 5, the accelerator opening change amount ΔAPO is compared with zero. When the accelerator opening change amount ΔAPO exceeds zero, that is, when the accelerator opening change amount ΔAPO is positive, it is determined that the vehicle is accelerating, and the routine proceeds to step 6 to set the acceleration flag = 1. In other words, it is determined from steps 1, 4 and 5 that the vehicle is currently in the LP-EGR region by acceleration, that is, the operating point has shifted from the non-LP-EGR region to the LP-EGR region by acceleration.

  In step 7, a timer is started (timer value t1 = 0). This timer is for measuring the elapsed time from the timing when the operating point shifts from the non-LP-EGR region to the LP-EGR region due to acceleration.

  In step 8, an assist torque amount [Nm] is calculated by searching a table having the contents shown in FIG. 7 from the accelerator opening change ΔAPO amount, and the assist torque amount command value Tast [Nm] is calculated in step 9. ]. As shown in FIG. 7, the assist torque amount is a value that increases as the accelerator opening change amount ΔAPO (degree of acceleration) increases. Further, the assist torque amount for an engine having a relatively large intake pipe volume is a value that is larger than the assist torque amount for an engine having a relatively small intake pipe volume.

  FIG. 7 covers various engines that originally differ in intake pipe volume. Here, for simplification, the intake pipe volume is shown separately for three engines of large, medium, and small. For this reason, there are only three linear characteristics. If the engine specification is determined, the intake pipe volume is uniquely determined. Therefore, if the engine specification is determined, the characteristic of FIG. 7 is a characteristic of only one straight line.

  Here, the reason why the assist torque amount is increased as the accelerator opening change amount ΔAPO (the degree of acceleration) increases is as follows. That is, in an engine having the same intake pipe volume, even if the degree of acceleration is different, an acceleration feeling corresponding to the different degree of acceleration is obtained.

  In step 10, the electromagnetic clutch ON flag is set to 1 in order to assist the engine torque with the torque generated by the motor generator 51 at the timing of shifting from the non-LP-EGR region to the LP-EGR region due to acceleration. As a result, the electromagnetic clutch 52 is connected and the engine 1 and the motor generator 51 are connected.

  Since the acceleration flag is set to 1 in step 6 this time, the process proceeds from step 2 to step 11 onward from the next time. In step 11, the timer value t1 is compared with the predetermined value B. The predetermined value B is a value for determining the end of torque assist processing by the motor generator 51 (processing for adding assist torque to the engine torque by the motor generator 51). When the timer value t1 is less than the predetermined value B, it is determined that torque assist processing by the motor generator 51 is still necessary, and the routine proceeds to step 12. In step 12, the value of “Tast (previous)”, which is the previous value of the assist torque amount command value, is directly transferred to the current assist torque amount command value Tast, thereby maintaining the assist torque amount. At this time, the operation of step 10 is executed. As long as the timer value t1 is less than the predetermined value B in step 11, the operations of steps 12 and 10 are repeatedly executed.

  Eventually, when the timer value t1 becomes equal to or greater than the predetermined value B in step 11, it is determined that the torque assist process by the motor generator 51 has come to an end. At this time, the routine proceeds to step 13 where the acceleration flag = 0. This prepares for the next acceleration when shifting from the non-LP-EGR region to the LP-EGR region. In steps 14 and 15, zero is set to the assist torque amount command value Tast, and the electromagnetic clutch ON flag = 0. As a result, the electromagnetic clutch 52 is disconnected and the connection between the engine 1 and the motor generator 51 is released.

  On the other hand, when the operating point is not in the LP-EGR region in step 1, when the absolute value | ΔAPO | of the accelerator opening change amount is equal to or smaller than a predetermined value A in step 4 (steady state), the accelerator opening change in step 5 When the amount ΔAPO is not positive, it is determined that the torque assist process is unnecessary. At this time, the routine proceeds to steps 16 and 17, where the assist torque amount command value Tast is set to zero, and the electromagnetic clutch ON flag = 0.

  In a flow (not shown) provided in the motor controller 55, when the electromagnetic clutch ON flag = 0, the current to the electromagnetic clutch 52 is cut off, and the electromagnetic clutch 52 is in a disconnected state. When the electromagnetic clutch ON flag = 1, an electric current is passed through the electromagnetic solenoid valve 53 to connect the electromagnetic clutch 52 and connect the motor generator 51 and the engine 1. Further, in a flow (not shown) provided in the motor controller 55, the assist torque amount command value Tast is converted into a current value and is sent to the stator of the motor generator 51, whereby the assist torque of the assist torque amount command value Tast is transmitted to the motor generator 51. Is generated.

  Next, the flow of FIG. 8 will be described. In step 21, it is determined whether or not the engine operating point is in the non-LP-EGR region shown in FIG. When the operating point is in the non-LP-EGR region, the process proceeds to step 22. In step 22, it is checked whether or not the deceleration flag (initially set to zero when the engine is started) = 1. Here, assuming that the deceleration flag = 0, the process proceeds to step 23.

  In step 23, the accelerator opening change amount ΔAPO is calculated based on the accelerator opening APO detected by the accelerator sensor 43. The accelerator opening APO is sent from the engine controller 41 to the motor controller 55 via the CAN communication device 56.

  In step 24, the absolute value | ΔAPO | of the accelerator opening change amount is compared with a predetermined value C. The predetermined value C is set in advance as a value for determining whether or not it is a transition time (acceleration and deceleration). The predetermined value C may be the same value as the predetermined value A in step 4 of FIG. When the absolute value | ΔAPO | of the accelerator opening change amount exceeds the predetermined value C, it is determined that the engine is in transition, and the process proceeds to step 25.

  In step 25, the accelerator opening change amount ΔAPO is compared with zero. When the accelerator opening change amount ΔAPO is less than zero, that is, when the accelerator opening change amount ΔAPO is negative, it is determined that the vehicle is decelerating, and the routine proceeds to step 26 to set the deceleration flag = 1. In other words, from steps 21, 24, 25, it is determined that the vehicle is currently in the non-LP-EGR region due to deceleration, that is, the operating point has shifted from the LP-EGR region to the non-LP-EGR region due to deceleration.

  In step 27, a timer is started (timer value t2 = 0). This timer is for measuring the elapsed time from the timing when the operating point shifts from the LP-EGR region to the non-LP-EGR region due to deceleration.

  In step 28, a power regeneration amount [kW] is calculated by searching a table having the contents shown in FIG. 9 from the absolute value | ΔAPO | of the accelerator opening change amount, and the power regeneration amount is calculated in step 29. The command value Tkis [kW] is entered. As shown in FIG. 9, the power regeneration amount is a value that increases as the absolute value | ΔAPO | (degree of deceleration) of the accelerator opening change amount increases. Further, the power regeneration amount in the case of an engine having a relatively large intake pipe volume is a value that is larger than the power regeneration amount in the case of an engine having a relatively small intake pipe volume.

  FIG. 9 covers various engines that originally differ in intake pipe volume. Here, for simplification, the intake pipe volume is shown separately for three engines of large, medium, and small. For this reason, there are only three linear characteristics. If the engine specification is determined, the intake pipe volume is uniquely determined. Therefore, if the engine specification is determined, the characteristic of FIG. 9 is a characteristic of only one straight line.

  Here, the reason why the power regeneration amount is increased as the absolute value | ΔAPO | (degree of deceleration) of the accelerator opening change amount increases is as follows. That is, in an engine having the same intake pipe volume, even if the degree of deceleration is different, a feeling of deceleration according to the different degree of deceleration is obtained. The amount of power regeneration corresponding to the intake pipe volume is determined by adaptation so that an optimal feeling of deceleration can be obtained.

  In step 30, since the engine torque is reduced by the amount of torque used for power generation of the motor generator 51 from the timing at which the LP-EGR region shifts to the non-LP-EGR region due to deceleration, the electromagnetic clutch ON flag is set to 1. As a result, the electromagnetic solenoid valve 53 is energized, the electromagnetic clutch 52 is connected, and the engine 1 and the motor generator 51 are connected, so that the motor generator 51 generates electric power (regenerates part of the engine torque). A current (electric power) generated in the motor generator 51 by power generation is stored in the battery 54.

  Since the deceleration flag = 1 is set at step 26 at this time, the process proceeds from step 22 to step 31 onward from the next time. In step 31, the timer value t2 is compared with the predetermined value D. The predetermined value D is a value for determining the end of power regeneration processing by the motor generator 51 (processing for regenerating part of the engine torque by the motor generator 51). When the timer value t2 is less than the predetermined value D, it is determined that the power regeneration process by the motor generator 51 is still necessary, and the process proceeds to step 32. In step 32, the power regeneration amount is maintained by moving the value of “Tkis (previous)”, which is the previous value of the power regeneration amount command value, directly to the current power regeneration amount command value Tkis. Also at this time, the operation of step 30 is executed. As long as the timer value t2 is less than the predetermined value D in step 31, the operations of steps 32 and 30 are repeated.

  Eventually, when the timer value t2 becomes equal to or greater than the predetermined value D in step 31, it is determined that the power regeneration process by the motor generator 51 has come to an end. At this time, the routine proceeds to step 33 where the deceleration flag = 0. This prepares for the next deceleration when shifting from the LP-EGR region to the non-LP-EGR region due to deceleration. In steps 34 and 35, zero is set in the power regeneration amount command value Tkis, and the electromagnetic clutch ON flag = 0. As a result, the electromagnetic clutch 52 is disconnected and the connection between the engine 1 and the motor generator 51 is released.

  On the other hand, when the operating point is not in the non-LP-EGR region at step 21, when the absolute value of the accelerator opening change amount is equal to or less than the predetermined value C at step 24 (during steady state), the accelerator opening change amount ΔAPO at step 25. When is not positive, it is determined that the power regeneration process is unnecessary. At this time, the routine proceeds to steps 36 and 37, where zero is set in the power regeneration amount command value Tkis, and the electromagnetic clutch ON flag = 0.

  In a flow (not shown) provided in the motor controller 55, when the electromagnetic clutch ON flag = 0, the current to the electromagnetic clutch 52 is cut off, and the electromagnetic clutch 52 is in a disconnected state. When the electromagnetic clutch ON flag = 1, a current is passed through the electromagnetic clutch 52 to connect the motor generator 51 and the engine 1. Further, in a flow (not shown) provided in the motor controller 55, a power regeneration amount command value Tkis is instructed to the motor generator 51, whereby the motor generator 51 is generated by the amount of the power regeneration amount command value.

  Next, the flowchart of FIG. 10 is for the engine controller 41 to calculate the ignition timing command value ADV. The flow in FIG. 10 is executed at regular time intervals (for example, every 10 ms) independently of the flows in FIGS.

  In step 41, the average value of the knock signal from the knock sensor 47 is compared with a predetermined slice level S / L. When the average value of the knock signal exceeds the rice level S / L, it is determined that knocking has occurred, and the feedback amount is obtained by adding a constant value ΔE to “FB (previous)” which is the previous value of the feedback amount of the ignition timing. Let it be FB. The feedback amount FB is a correction amount for retarding the ignition timing. Here, knocking is avoided by retarding the ignition timing by a fixed value ΔE.

  Due to the retard of the ignition timing, the average value of the knock signal from the knock sensor 47 is reduced to the slice level S / L or less at step 41 next time. At this time, it is determined that knocking has not occurred, and the routine proceeds to step 43.

  In step 43, a value obtained by subtracting a constant value ΔF from “FB (previous)” which is the previous value of the feedback amount of the ignition timing is set as the feedback amount FB. Since the feedback amount FB is a correction amount for retarding the ignition timing, the operation in step 43 means that the ignition timing is advanced by a fixed value ΔF from the previous ignition timing command value. Here, the fixed value ΔF is set to a value smaller than the fixed value ΔE.

  If knocking occurs by the operations in steps 41 to 43, the ignition timing is retarded stepwise by a constant value ΔE. If knocking does not occur thereafter, the ignition timing is gradually advanced by a constant value ΔF. When knocking occurs, the operation of retarding the ignition timing step by step by a constant value ΔE is repeated. As a result, the ignition timing is kept at the basic ignition timing ADV0 as much as possible while avoiding knocking.

  In step 44, it is determined whether or not the engine operating point is in the LP-EGR region shown in FIG. When the operating point is in the non-LP-EGR region, the process proceeds to steps 45 and 46.

  Steps 45 and 46 are parts for calculating the ignition timing command value ADV when the operating point is in the non-LP-EGR region. First, at step 45, a basic ignition timing ADV0 [° BTDC] is obtained at which MBT is obtained in accordance with an operating point determined from the engine load and the rotational speed.

  In step 46, a value obtained by subtracting the feedback amount FB from the basic ignition timing ADV is used as an ignition timing command value ADV [° BTDC], that is, the ignition timing command value ADV is calculated by the following equation. This is for the following reason. That is, because the ignition timing command value ADV is a value [° BTDC] measured from the compression top dead center to the advance side, it is necessary to subtract from ADV 0 in order to retard the ignition timing by the feedback amount FB.

    ADV = ADV0−FB (3)

  On the other hand, when the engine operating point is in the LP-EGR region at step 44, the routine proceeds to step 47 and thereafter.

  Steps 47 to 52 are parts for calculating the ignition timing command value ADV when the operating point is in the LP-EGR region. First, in step 47, the basic ignition timing ADV0 [° BTDC] is calculated so that MBT is obtained even when the operating point is in the LP-EGR region. However, since the EGR gas is introduced into the combustion chamber 7 in the LP-EGR region, it is necessary to consider the EGR gas component. Therefore, it is considered that the LP-EGR region is in the same region in terms of operation point, and the state where EGR gas is introduced into the combustion chamber 7 is searched from the target EGR ratio by searching a table having the contents shown in FIG. However, the basic ignition timing ADV0 is calculated so that MBT is obtained. As shown in FIG. 11, the basic ignition timing ADV0 is a value that increases toward the advance side as the target EGR ratio increases. This is due to the following reason. That is, the combustion state becomes worse as the target EGR ratio increases. Therefore, by setting the basic ignition timing ADV0 to the advance side, the worsened combustion is stabilized.

In step 48, the actual EGR ratio is obtained by searching a table having the contents shown in FIG. 12 from the O ₂ concentration in the intake pipe (hereinafter simply referred to as “intake pipe”) from the compressor 23 downstream to the combustion chamber 7 inlet. calculate. As shown in FIG. 12, the actual EGR ratio is a value that increases as the O ₂ concentration in the intake pipe decreases. The O ₂ concentration in the intake pipe is detected by an O ₂ concentration sensor 45 provided in the intake collector 4b.

  In step 49, the difference between the target EGR ratio and the actual EGR ratio is set as the difference EGR ratio ΔR, that is, the difference EGR ratio ΔR is calculated by the following equation.

    ΔR = target EGR ratio−actual EGR ratio (4)

  In step 50, the difference EGR ratio correction amount HOS1 [°] is calculated by searching a table having the contents shown in FIG. 13 from the difference EGR ratio ΔR. As shown in FIG. 13, when the difference EGR ratio ΔR is positive, the difference EGR ratio correction amount HOS1 decreases with a negative value, and when the difference EGR ratio ΔR is negative, ΔR increases with a negative value. It is a value that increases with a positive value.

  The difference EGR ratio correction amount HOS1 is a value that corrects the ignition timing to the advance side when this value is positive, and corrects the ignition timing to the retard side when this value is negative. When the difference EGR ratio ΔR is positive, the difference EGR ratio correction amount HOS1 is given as a negative value (that is, the ignition timing is corrected to the retard side) for the following reason. That is, at the time of acceleration when the operating point shifts from the non-LP-EGR region to the LP-EGR region, the actual EGR ratio becomes smaller than the target EGR ratio for a while after shifting to the LP-EGR region. When the actual EGR ratio is smaller than the target EGR ratio (when the difference EGR ratio ΔR is positive), the combustion state of the working gas in the combustion chamber 7 is improved by the difference (ΔR) and knocking is likely to occur. It becomes. Therefore, at this time, the occurrence of knocking is suppressed by correcting the ignition timing to the retard side with respect to the basic ignition timing ADV0.

  On the other hand, when the actual EGR ratio is larger than the target EGR ratio (when the difference EGR ratio ΔR is negative), the difference EGR ratio correction amount HOS1 is given as a positive value (that is, the ignition timing is corrected to the advance side). Because of the reason. That is, when the actual EGR ratio is larger than the target EGR ratio, the combustion state of the working gas in the combustion chamber 7 becomes worse by the amount of ΔR, and the engine becomes unstable. Therefore, at this time, the combustion of the working gas is stabilized by correcting the ignition timing to the advance side with respect to the basic ignition timing ADV0.

  In FIG. 13, the difference EGR ratio correction amount HOS1 is set to zero when the difference EGR ratio ΔR is between the predetermined value a and the predetermined value b. This is hysteresis.

  In step 51, the exhaust temperature correction amount HOS2 [°] is calculated by searching a table having the contents shown in FIG. 14 from the exhaust temperature Texh detected by the exhaust temperature sensor 46. As shown in FIG. 14, the exhaust gas temperature correction amount HOS2 is a positive value when the exhaust gas temperature Texh is higher than the set temperature Tset, and a negative value when the exhaust gas temperature Texh is lower than the set temperature Tset. When the exhaust temperature correction amount HOS2 is a positive value, the ignition timing is advanced by this correction amount HOS2, and when the exhaust temperature correction amount HOS2 is a negative value, the ignition timing is retarded by this correction amount HOS2. . Here, the set temperature Tset is the exhaust temperature of the LP-EGR valve 17 portion when the basic ignition timing ADV0 is set.

  In the present embodiment, the exhaust temperature sensor 46 is attached at a position immediately downstream of the LP-EGR valve 17, but is not limited to this attachment position. In the present embodiment, the exhaust gas temperature is detected by the exhaust gas temperature sensor 46, but the exhaust gas temperature may be estimated.

  The reason why the ignition timing is retarded when the exhaust temperature Texh is lower than the set temperature Tset is as follows. That is, even when the operating point shifts from the non-LP-EGR region to the LP-EGR region during the same acceleration, the amount of EGR gas introduced into the combustion chamber 7 decreases when the exhaust temperature Texh is lower than the set temperature Tset. When the amount of EGR gas introduced into the combustion chamber 7 decreases, knocking may occur. This is because it is necessary to retard the ignition timing in order to avoid knocking.

  The reason why the ignition timing is advanced when the exhaust temperature Texh is higher than the set temperature Tset is as follows. That is, even during the same acceleration when shifting to the LP-EGR region, when the exhaust gas temperature Texh is higher than the set temperature Tset, the amount of EGR gas introduced into the combustion chamber 7 increases and combustion becomes unstable. This is because it is necessary to advance the ignition timing in order to stabilize the combustion.

  In step 52, the exhaust temperature correction amount HOS2 and the differential EGR ratio correction amount HOS1 are added to the basic ignition timing ADV0, and the value obtained by subtracting FB from ADV0 is set as the ignition timing command value ADV [° BTDC], that is, the ignition timing by the following equation. A command value ADV is calculated.

    ADV = ADV0 + HOS1 + HOS2-FB (5)

  In a flow (not shown) provided in the engine controller 41, the ignition timing command value ADV calculated in this way is output to the power transistor of the ignition device. The power transistor is provided on the primary side of the ignition coil, and spark ignition is performed by the spark plug 9 by cutting off the primary current at the timing of the ignition timing command value ADV.

  Here, the effect of this embodiment is demonstrated.

  In the present embodiment, in the control device for the hybrid vehicle 50 using the engine 1 and the motor generator 51 as drive sources, the electromagnetic clutch 52 (connection / disconnection means), the LP-EGR device 14, the torque assist means (55), Is provided. The electromagnetic clutch 52 connects and disconnects the engine 1 and the motor generator 51. The LP-EGR device 14 opens the LP-EGR valve 17 and supplies EGR gas to the combustion chamber 7 in a predetermined LP-EGR region. The torque assist means (55) instructs the electromagnetic clutch 52 when the operating point of the engine shifts from the non-LP-EGR region to the LP-EGR region due to acceleration (when accelerating with an increase in the target EGR ratio). The motor generator 51 and the engine 1 are connected. The motor generator 51 assists the engine torque generated by the engine 1 according to the intake pipe volume of the engine 1 and the intake pipe volume from the LP-EGR valve 17 to the inlet of the combustion chamber 7. Further, when the engine operating point shifts from the LP-EGR region to the non-LP-EGR region due to deceleration (when decelerating with a decrease in the target EGR ratio), the electromagnetic clutch 52 is instructed, and the motor generator 51 and the engine 1 is connected. Then, according to the intake pipe volume from the LP-EGR valve 17 to the inlet of the combustion chamber 7, the motor generator 51 is generated with the engine torque generated by the engine 1 to regenerate electric power. According to this embodiment, at the time of acceleration in which the rise of the engine torque is delayed due to the delay in introduction of EGR gas, smooth acceleration can be performed without the delay in the rise of the torque. In addition, when the engine torque becomes excessive due to the delay in stopping the EGR gas, the excessive torque can be eliminated and smooth deceleration can be performed.

  In the present embodiment, the engine is a gasoline engine and includes basic ignition timing calculation means (41) and ignition timing feedback control means (41). The basic ignition timing calculating means (41) calculates the basic ignition timing ADV0 in the LP-EGR region according to the target EGR ratio. The ignition timing feedback control means (41) feedback-controls the ignition timing to the retard side from the basic ignition timing ADV0 when knocking occurs when the operating point of the engine shifts to the LP-EGR region due to acceleration. Thus, knocking is avoided by feedback control of the ignition timing. However, during the acceleration when the engine operating point shifts from the non-LP-EGR region to the LP-EGR region, while the introduction of EGR gas into the combustion chamber 7 is delayed, the actual EGR ratio becomes smaller than the target EGR ratio, and knocking occurs. It will happen. Then, since feedback control of the ignition timing for avoiding knocking is performed, the ignition timing is retarded. As a result, the actual engine torque falls below the target engine torque in the early stage of acceleration, and the feeling of acceleration becomes insufficient, and the desired feeling of acceleration cannot be obtained. In this case, in this embodiment, the engine torque is assisted by the motor generator 51 during acceleration when the operating point of the engine shifts from the non-LP-EGR region to the LP-EGR region. As a result, it is possible to achieve smooth acceleration while avoiding knocking and eliminating the delay in starting engine torque at the initial stage of acceleration that occurs with the delay in introduction of EGR gas.

  In the present embodiment, the assist torque amount by the motor generator 51 or the power regeneration amount of the motor generator 51 increases as the intake pipe volume increases. As a result, smooth acceleration and deceleration can be performed even with engines having different intake pipe volumes.

  In the present embodiment, the assist torque amount by the motor generator 51 or the power regeneration amount of the motor generator 51 is also a value corresponding to the accelerator opening change amount. As a result, even if the degree of acceleration or deceleration differs between engines having the same intake pipe volume, it is possible to obtain a feeling of acceleration or a feeling of deceleration according to the different degree of acceleration or deceleration.

  In the present embodiment, the actual LP-EGR ratio estimation means (41), the difference EGR ratio calculation means (41), the first ignition timing correction amount calculation means (41), and the first ignition timing correction means (41) Is provided. When the engine operating point shifts from the non-LP-EGR region to the LP-EGR region, the actual LP-EGR ratio estimation means (41) estimates the actual EGR ratio in the shifted LP-EGR region. The difference EGR ratio calculation means (41) calculates a difference EGR ratio ΔR (difference) between the target EGR ratio and the estimated actual EGR ratio. The first ignition timing correction amount calculation means (41) calculates a difference EGR ratio correction amount HOS1 (first ignition timing correction amount) corresponding to the difference EGR ratio ΔR so that the estimated actual EGR ratio matches the target EGR ratio. To do. The first ignition timing correction means (41) corrects the basic ignition timing ADV0 with the differential EGR ratio correction amount HOS1. Thus, during acceleration in which the operating point shifts from the non-LP-EGR region to the LP-EGR region, it is possible to suppress the occurrence of knocking when the actual EGR ratio is smaller than the target EGR ratio for a while after the shift.

  In the present embodiment, an exhaust temperature sensor 46 (exhaust temperature detection means), a second ignition timing correction amount calculation means (41), and a second ignition timing correction means (41) are provided. The exhaust temperature sensor 46 detects the exhaust temperature Texh. When the exhaust gas temperature Texh deviates from a predetermined set temperature Tset, the second ignition timing correction amount calculating means (41) performs an exhaust gas temperature correction amount HOS2 (second ignition timing) according to the temperature difference from the set temperature Tset. Correction amount) is calculated. The second ignition timing correction means (41) corrects the basic ignition timing ADV0 with the exhaust temperature correction amount HOS2. As a result, even when the operating point shifts from the non-LP-EGR region to the LP-EGR region during the same acceleration, the exhaust gas temperature is lower than the set temperature and the actual EGR gas amount flowing into the combustion chamber 7 decreases. Can tend to knock.

  In the embodiment, the case where the LP-EGR device is applied to the gasoline engine has been described. However, the present invention is not limited to this case, and the present invention can be applied to the case where the LP-EGR device is applied to the diesel engine. In a diesel engine, an exhaust aftertreatment device including a DPF (Diesel Particulate Filter) is provided in an exhaust pipe. There are various types of exhaust aftertreatment devices. For example, an oxidation catalyst, a DPF, and a NOx trap catalyst are provided in this order from the upstream side of the exhaust pipe. In addition to this, various types of exhaust aftertreatment devices are provided, but anyway, since DPF is always included, an LP-EGR device is provided with an EGR gas outlet in the LP-EGR device downstream of the DPF. Do it.

  In a diesel engine equipped with an LP-EGR device, when the operating point shifts from the non-LP-EGR region to the LP-EGR region due to acceleration, there is a delay in the rise of the engine torque until the EGR gas actually flows into the combustion chamber. is there. In this case, while the supply of EGR gas to the combustion chamber is delayed, the actual EGR ratio becomes smaller than the target EGR ratio, and NOx increases or knocking occurs. If the fuel injection amount is decreased in order to suppress the increase in NOx and the occurrence of knocking, the actual engine torque will be lower than the target engine torque, and the desired acceleration feeling cannot be obtained. Therefore, a desired acceleration feeling can be obtained by assisting the engine torque generated by the engine according to the intake pipe volume by the motor generator during acceleration when the operating point shifts from the non-LP-EGR region to the LP-EGR region. It is done.

  Similarly, when the operating point shifts from the LP-EGR region to the non-LP-EGR region due to deceleration, there is a response delay until the flow of EGR gas into the combustion chamber stops. Since the amount of fresh air cannot be reduced while the flow of EGR gas into the combustion chamber is not stopped, the actual engine torque exceeds the target engine torque, and the desired deceleration feeling cannot be obtained. Therefore, at the time of deceleration at which the operating point shifts from the LP-EGR region to the non-LP-EGR region, the motor generator 51 generates electric power with the engine torque generated by the engine according to the intake pipe volume, thereby generating the desired power. The feeling of deceleration is obtained.

DESCRIPTION OF SYMBOLS 1 Gasoline engine 4 Intake passage 4a Intake pipe 4b Intake collector 8 Fuel injection valve 9 Spark plug 11 Intake passage 11b Exhaust pipe 12 Manifold catalyst 13 Main catalyst 14 LP-EGR device 15 EGR passage 16 EGR cooler 17 LP-EGR valve 41 Engine controller (Basic ignition timing calculation means, ignition timing feedback control means, actual EGR ratio estimation means, differential EGR ratio calculation means, first ignition timing correction amount calculation means, first ignition timing correction means, second ignition timing correction amount calculation means, Second ignition timing correction means)
46 Exhaust temperature sensor (exhaust temperature detection means)
47 Knock sensor 50 Hybrid vehicle 51 Motor generator 52 Electromagnetic clutch (connection / disconnection means)
55 Motor controller (torque assist, power regeneration means)

Claims (8)

In a hybrid vehicle control apparatus using an engine and a motor generator as drive sources,
Connecting / disconnecting means for connecting / disconnecting the engine and the motor generator;
An LP-EGR device that opens an LP-EGR valve in a predetermined LP-EGR region and supplies EGR gas to the combustion chamber;
When accelerating with an increase in the target EGR ratio, the connection / disconnection means is instructed to connect the motor generator and the engine, and the motor generator causes the intake pipe volume of the engine to be the LP- According to the intake pipe volume from the EGR valve to the combustion chamber inlet, assists the engine torque generated by the engine or instructs the connection / disconnection means at the time of deceleration accompanied by a decrease in the target EGR ratio, The generator is connected to the engine, and the motor generator is controlled by the engine torque generated by the engine according to the intake pipe volume of the engine and the intake pipe volume from the LP-EGR valve to the combustion chamber inlet. Provide torque assist and power regeneration means to generate electricity and regenerate power. And a control apparatus for a hybrid vehicle.   When accelerating with an increase in the target EGR ratio, the operating point of the engine shifts from the non-LP-EGR region to the LP-EGR region due to acceleration, and when decelerating with a decrease in the target EGR ratio 2. The hybrid vehicle control device according to claim 1, wherein the engine operating point shifts from the LP-EGR region to a non-LP-EGR region. The engine is a gasoline engine;
Basic ignition timing calculation means for calculating basic ignition timing in accordance with the target EGR ratio in the LP-EGR region;
Ignition timing feedback control means for performing feedback control of the ignition timing to the retard side from the basic ignition timing when knocking occurs when the operating point of the engine shifts to the LP-EGR region due to the acceleration. The control apparatus for a hybrid vehicle according to claim 2.   4. The control apparatus for a hybrid vehicle according to claim 2, wherein the assist torque amount by the motor generator or the electric power regeneration amount of the motor generator increases as the intake pipe volume increases.   The hybrid vehicle control device according to claim 4, wherein the assist torque amount by the motor generator or the electric power regeneration amount of the motor generator is also a value corresponding to an accelerator opening change amount. An actual EGR ratio estimation means for estimating an actual EGR ratio in the LP-EGR region after the transition when the operating point of the engine transitions from the non-LP-EGR region to the LP-EGR region;
A difference EGR ratio calculating means for calculating a difference between the target EGR ratio and the estimated actual EGR ratio;
First ignition timing correction amount calculating means for calculating a first ignition timing correction amount according to the calculated difference EGR ratio so that the estimated actual EGR ratio matches the target EGR ratio;
The hybrid vehicle control device according to any one of claims 3 to 5, further comprising: a first ignition timing correction unit that corrects the basic ignition timing with the calculated first ignition timing correction amount. . Exhaust temperature detection / estimation means for detecting or estimating the exhaust temperature;
A second ignition timing correction amount calculating means for calculating a second ignition timing correction amount according to a temperature difference from the set temperature when the detected or estimated exhaust temperature deviates from a predetermined set temperature;
The hybrid vehicle control device according to any one of claims 3 to 6, further comprising: a second ignition timing correction unit that corrects the basic ignition timing by the calculated second ignition timing correction amount. .   The torque assist / power regeneration means instructs the connection / disconnection means even when the operating point of the engine changes to the side where the EGR ratio becomes larger in the LP-EGR region due to the acceleration, and The engine torque that is generated by the engine in accordance with the intake pipe volume of the engine and the intake pipe volume from the LP-EGR valve to the combustion chamber inlet. Or when the operating point of the engine changes to a side where the EGR ratio becomes smaller in the LP-EGR region due to the deceleration, the connection / disconnection means is instructed, and the motor generator and the The engine is connected to the engine, and the intake pipe volume of the engine is the LP-EGR. 8. The electric power regeneration is performed by generating the motor generator with an engine torque generated by the engine in accordance with an intake pipe volume to a combustion chamber inlet, according to any one of claims 2 to 7. Control device for hybrid vehicle.

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