JP2007211650A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine, which effectively warms up an internal combustion engine. <P>SOLUTION: An engine ECU 100 variably controls the operating speed of a piston of each cylinder during the catalyst warmup control in which the ignition timing is controllably retarded. The control is performed by giving a drive force from a motor 500 to the engine through a crankshaft 205. In the deceleration period ΔTd from the position of the piston to be ignited to the position of the piston advanced to 90° in crank angle which is set, for example, in an expansion stroke, the speed of the piston is lowered and the combustion time is secured. In the acceleration period ΔTi from the changeover position Tc where the deceleration period ΔTd is terminated, to BDC, the speed of the piston is increased, and the discharge of unburned fuel is promoted. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technical field of a control device for an internal combustion engine.

  In this kind of technical field, what warms up a catalyst is proposed (for example, refer patent document 1). According to the engine control device disclosed in Patent Document 1 (hereinafter referred to as “conventional technology”), when the ignition timing is retarded and the exhaust gas temperature is increased during engine cold start, the actual engine speed fluctuation It is said that by controlling the combustion state of the engine according to the state, it is possible to retard the ignition timing as much as possible and maximize the temperature rise effect of the catalyst.

  A technique has also been proposed in which the piston speed after compression top dead center is decelerated by a motor in a non-knock region and then accelerated to improve engine efficiency (see, for example, Patent Document 2).

  In addition, a technique has been proposed in which the piston speed at the compression top dead center is increased by a motor when the engine is started to improve the startability (see, for example, Patent Document 3).

Japanese Patent Laid-Open No. 11-107838 JP 2004-84607 A JP 2004-44491 A

  When retarding the ignition timing for the purpose of warming up the internal combustion engine, if the expansion stroke ends during combustion, combustion becomes insufficient. There is a limit. On the other hand, when priority is given to the purpose of promoting warm-up, the expansion stroke ends during combustion, combustion stability may deteriorate, and torque fluctuation may increase. That is, the conventional technique has a technical problem that the internal combustion engine may not be sufficiently warmed up.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a control device for an internal combustion engine capable of effectively warming up the internal combustion engine.

  In order to solve the above-described problems, an internal combustion engine control apparatus according to the present invention controls an internal combustion engine in a vehicle having an internal combustion engine having a piston and a crankshaft connected to the piston as at least a part of a power source. A control device for an internal combustion engine, the driving force applying means capable of applying a driving force to the piston, and at least one of a warm-up period defined as a period during which at least a part of the internal combustion engine should be warmed up And a driving force control means for controlling the driving force applying means so as to apply the driving force to the piston in at least one of a positive direction and a negative direction of the movement direction. To do.

  In the control device for an internal combustion engine according to the present invention, the “internal combustion engine” is a concept including an engine having a piston and a crankshaft and converting combustion of fuel into motive power. For example, the piston is connected to a piston via a connecting rod. 4 cycle type reciprocating engine having a crankshaft connected to each other. Of course, the internal combustion engine according to the present invention may have other combustion types such as a 2-cycle type in addition to a 4-cycle type.

  The control apparatus for an internal combustion engine according to the present invention includes, for example, an electric driving force applying unit that can apply a driving force to a piston via a crankshaft, for example, including a motor. Furthermore, a driving force control means including, for example, a microcomputer for controlling the driving force applying means is provided.

  The “driving force applying means” according to the present invention is a concept including means capable of applying a driving force to the piston in at least one of the positive direction and the negative direction of the movement direction. In this case, any driving force applying means that applies a driving force as a rotational force or torque to the piston, for example, via a crankshaft, and further, for example, via a connecting rod can be made relatively easy by existing mechanism technology. Thus, the driving force applying means can be constructed. For example, the driving force applying means can be provided by using a motor or a motor generator constituting a motor device or a motor generator device provided in a hybrid power output device, or by providing such a motor or motor generator exclusively. Can be constructed.

  The driving force applying means is not limited to transmitting the driving force from the crankshaft to the piston via the connecting rod. Furthermore, in addition to the structure in which the driving force is applied through the crankshaft or the connecting rod, the driving force may be applied directly to the piston or indirectly through another mechanism.

  According to the control device for an internal combustion engine of the present invention, during the operation, the driving force applying means is controlled in the positive direction of the movement direction with respect to the piston in at least a part of the warm-up period under the control of the driving force control means. A driving force is applied in at least one direction of the negative direction. That is, the piston speed is variable without being uniquely determined by the engine speed and crank angle (or crank position) of the internal combustion engine.

  Here, the “warm-up period” according to the present invention refers to an exhaust pipe communicating with at least a part of an internal combustion engine such as a start-up period, a catalyst warm-up period, or a low-temperature (cold) start-up period, for example, a catalyst device or a catalyst device. It is a concept encompassing a period defined as something that should be warmed up. Such a warm-up period may be defined as at least a part of a period in which the cooling water temperature of the internal combustion engine is equal to or less than (or less than) a predetermined value, or a period in which the outside air temperature is equal to or less than (or less than) a predetermined value. Alternatively, it may be a period defined by some index that is set in advance so that it can effectively define the period for warming up the object to be warmed up experimentally, empirically, or based on simulation or the like. .

  According to the control apparatus for an internal combustion engine according to the present invention, the piston force is relatively decreased by the driving force applying means, for example, at the initial stage of the expansion stroke (for example, the piston position range including the vicinity of the top dead center or the ignition position). Thus, it is possible to sufficiently ensure the flame growth time, and for example, it is possible to control the ignition timing further on the retard side as compared with the case where no such control is performed. In this case, it is possible to supply relatively high temperature exhaust gas to the exhaust system, and it is possible to promote warming up of the internal combustion engine during the warming up period.

  Alternatively, according to the control device for an internal combustion engine according to the present invention, the driving force application means relatively increases the piston speed, for example, at the later stage of the expansion stroke (for example, the range of the piston position including the vicinity of the bottom dead center), For example, it is possible to increase the discharge amount of the unburned air-fuel mixture as compared with the case where no such control is performed. Therefore, so-called “afterburning” of burning the unburned air-fuel mixture in the exhaust system is promoted, and warming up of the internal combustion engine during the warming up period can be promoted. That is, according to the control device for an internal combustion engine according to the present invention, the internal combustion engine can be effectively warmed up.

  In one aspect of the control apparatus for an internal combustion engine according to the present invention, there is further provided warm-up means for warming up at least a part of the internal combustion engine by retarding an ignition timing of the internal combustion engine with respect to a predetermined reference timing. And the driving force control means applies the driving force during a period in which the ignition timing is retarded as at least a part of the warm-up period.

  According to this aspect, the internal combustion engine control apparatus delays the ignition timing with respect to the predetermined reference timing, thereby, for example, exhaust discharged into an exhaust system including an exhaust port, an exhaust manifold, an exhaust pipe, or the like. Is provided with a warming-up means for warming up, for example, a catalyst device or the like. The driving force control unit controls the driving force applying unit so that the driving force is applied to the piston during a period in which the ignition timing is retarded by the warming-up unit as at least a part of the warm-up period.

  When the ignition timing is retarded in this way, as described above, the retard amount may have a limit due to combustion stability. However, in this aspect, for example, the flame growth time or An appropriate driving force is applied to the piston, for example, the piston speed is lowered so that the combustion time can be taken longer, so that the internal combustion engine can be warmed up effectively.

  In this aspect, the warm-up means retards the ignition timing so that the ignition timing is within the expansion stroke of the internal combustion engine, and the driving force control means sets the ignition timing to the ignition timing in the expansion stroke. The speed of the piston is reduced in at least a part of the range defined by the corresponding piston position and the bottom dead center of the internal combustion engine, including the vicinity of the piston position corresponding to the ignition timing. A driving force may be applied.

  In this case, the ignition timing is set within the expansion stroke, and the piston speed is determined so that the piston position corresponds to the piston position corresponding to the ignition timing (hereinafter referred to as “ignition position” as appropriate) and the bottom dead center (hereinafter referred to as BDC (referred to as appropriate). It is controlled to decrease in at least a part of the range including the vicinity of the ignition position in the range defined by “Bottom Death Center”).

  Therefore, the flame growth time is ensured, and the retard amount of the ignition timing by the warm-up means can be set larger than in the case where no such control is performed. Alternatively, it is possible to improve the combustion state while maintaining the retard amount. Therefore, for example, warm-up of the catalyst device or the like is preferably promoted.

  The “at least part of the range including the vicinity of the piston position corresponding to the ignition timing” may include the ignition position and the entire area from the ignition position to the BDC, or TDC (Top Death Center: in the compression process). The range of the piston position may be about half of the expansion stroke defined by the top dead center) and the BDC. Such a range of the piston position at which the piston speed is reduced may be determined in advance as a period in which the fuel can be sufficiently burned experimentally, empirically, or based on simulation.

  In another aspect of the control apparatus for an internal combustion engine according to the present invention, the drive force control means drives the drive so that the speed of the piston increases in at least a part of the expansion stroke of the internal combustion engine including the vicinity of bottom dead center. Control the force applying means.

  In this case, the piston speed is increased in at least a part of the expansion stroke including the vicinity of the bottom dead center, and the exhaust of the unburned mixture is promoted. Therefore, for example, the unburned air-fuel mixture that burns in the exhaust port, the exhaust manifold, the exhaust pipe, or the like is increased, and warming up of the catalyst device or the like is preferably promoted.

  In the present invention, “at least a part of the expansion stroke including the bottom dead center” may be a wide range from the ignition position to the BDC, for example, or may be a very partial range near the BDC. Good. The range of the piston position that increases the piston speed in this way may be determined in advance as a range in which the unburned fuel can be sufficiently shared with the exhaust system based on experiments, experience, or simulation. .

  Moreover, after combining the deceleration control of the piston as described above and the acceleration control of the piston, the piston is decelerated in a range that is relatively similar to the first half of the range from the ignition position to the BDC, and after sufficiently burning the fuel, The piston may be accelerated in a relatively similar range in the second half through a continuous or constant or indefinite interval, and unburned fuel may be quickly supplied to the exhaust system.

  In another aspect of the control device for an internal combustion engine according to the present invention, the internal combustion engine includes: (i) a plurality of cylinders each including the piston; and (ii) a fuel supply means for supplying fuel to each of the plurality of cylinders. The control device for the internal combustion engine has an air-fuel ratio in each of the cylinders in the plurality of cylinders and in other cylinders excluding the cylinders in the start-up period defined as at least a part of the warm-up period. And further comprising a supply control means for controlling the fuel supply means so that the lean air-fuel ratio is higher than the stoichiometric air-fuel ratio and the rich air-fuel ratio is lower than the stoichiometric air-fuel ratio. The driving force applying means is controlled so that the speed of the piston is reduced in at least a part of the expansion stroke in the cylinder in which the fuel ratio is set to the lean air-fuel ratio.

  According to this aspect, the internal combustion engine has a plurality of cylinders each including a piston and fuel supply means such as an injector for injecting fuel to each of the cylinders. The control device for the internal combustion engine is configured so that the air-fuel ratio in a part of the plurality of cylinders is a rich air-fuel ratio in the start period defined as at least a part of the warm-up period, and the air-fuel ratios of the remaining cylinders excluding the part Comprises a supply control means for controlling the fuel supply means so that the air-fuel ratio becomes lean.

  Cylinders that are set to lean air-fuel ratio, that is, that perform lean combustion, require a longer combustion time than cylinders that are set to rich-side air-fuel ratio, so output torque is reduced particularly during cold start, etc. Easy to do. According to this aspect, for the cylinder set to the lean side air-fuel ratio, the piston speed in at least a part of the expansion stroke is reduced by the driving force control means, so that the expansion stroke viewed in the time domain becomes relatively long. Combustion stability is suitably ensured. As a result, the torque difference with the cylinder set to the rich side air-fuel ratio, that is, the torque fluctuation when viewed as the whole internal combustion engine is reduced. That is, the internal combustion engine is effectively warmed up.

  When the internal combustion engine has a plurality of cylinders, the balance of the air-fuel ratio of each cylinder is not particularly limited.For example, the total number of cylinders set to the lean side air-fuel ratio and the cylinder set to the rich side air-fuel ratio are mutually It is desirable to be set equal. In this case, the air-fuel ratio may be controlled so that the air-fuel ratio when viewed as the whole internal combustion engine converges near the stoichiometric (that is, the stoichiometric air-fuel ratio).

  In the cylinder set to the lean air-fuel ratio, the ignition timing is often set before TDC (that is, on the advance side than TDC) because it is necessary to secure the combustion time. Strictly speaking, in such a case, since combustion starts in the latter stage of the compression stroke, which is the previous stage of the expansion stroke, as long as the piston speed is reduced in at least a part of the expansion stroke, the piston is subjected to deceleration control. The range of the position may straddle part of the compression stroke. However, if the range in which the speed characteristic of the piston changes in this way extends over two strokes, it may affect other cylinders. Therefore, in order to avoid such a concern, the cylinder set on the lean side For the cylinders set on the rich side, it is preferable that the mechanical cycle between the cylinders is set so as to alternately reach the combustion stroke.

  In the control apparatus for an internal combustion engine according to the present invention, the driving force applying means applies the driving force to the piston via the crankshaft and functions as a part of a power source of the vehicle together with the internal combustion engine. Including an electric motor.

  According to this aspect, since the driving force applying means has the form of an electric motor that functions as a part of the power source of the vehicle, the internal combustion engine can be warmed up efficiently and effectively.

  In addition, although the vehicle in this aspect is a hybrid vehicle, the mechanical or electrical configuration of the power source is not limited at all, and the power distribution between the electric motor and the internal combustion engine is not limited at all. For example, the configuration may be such that the power of the internal combustion engine is appropriately assisted by the electric motor, or the motor is assisted by the power of the internal combustion engine when traveling mainly by the electric motor and the required output cannot be satisfied by the output of the electric motor such as during a transition period. It may be configured to. Alternatively, the electric motor may take a configuration of a so-called motor generator having a function as a generator in addition to a function as an electric motor, and may be configured to appropriately input and output power by a motor generator device including the motor generator.

  Furthermore, in this case, the motor generator device includes a first motor generator that applies a driving force to the piston and a second motor generator that applies another driving force to the drive shaft of the hybrid vehicle. It may be configured. With this configuration, in the so-called parallel type hybrid vehicle or the like, the control device for the internal combustion engine according to the present invention is relatively obtained by using the first motor generator connected to the crankshaft side as the driving force applying means. Easy to build.

  In another aspect of the control apparatus for an internal combustion engine according to the present invention, at least a part of the internal combustion engine includes a catalyst installed in an exhaust path of the internal combustion engine.

  According to this aspect, since the target of warm-up includes a catalyst device that can communicate with the exhaust system, such as a three-way catalyst, an oxidation catalyst, a NOx storage reduction catalyst, or an HC adsorption cylinder, the piston speed can be increased. The engine is effectively warmed up by an increase in the exhaust gas temperature associated with the variable control.

  Such an operation and other advantages of the present invention will become apparent from the embodiments described below.

<Embodiment of the Invention>
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings as appropriate.

<1: First Embodiment>
<1-1: Configuration of Embodiment>
<1-1-1: Configuration of hybrid system>
First, the configuration of the hybrid system 10 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of the hybrid system 10.

  In FIG. 1, a hybrid system 10 includes an engine ECU (Electronic Control Unit) 100, an engine 200, a hybrid ECU 300, an inverter 400, a motor 500, and a battery 600, and controls the hybrid vehicle 20.

  The engine ECU 100 is an electronic control unit that includes an unillustrated CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and the like, and controls the overall operation of the hybrid system 10, and is related to the present invention. It is an example of "the control apparatus of an internal combustion engine".

  The engine 200 is a four-cylinder gasoline engine that functions as one of the power sources of the hybrid vehicle 10, and is an example of the “internal combustion engine” according to the present invention. A crankshaft 205 (to be described later) of the engine 200 is connected to a transmission mechanism 21 of the hybrid vehicle 20 including an axle, a transmission, a differential, and the like, and the power generated by the engine 200 is finally connected to the transmission mechanism 21. 22 is transmitted as a driving force. The detailed configuration of the engine 200 will be described later.

  The hybrid ECU 300 is an electronic control unit that is controlled by the engine ECU 100 at a higher level, and is configured to control the traveling of the hybrid vehicle 20 using the motor 500.

  The inverter 400 is a DC / AC converter that converts DC power supplied from the battery 600 into AC power and supplies the AC power to the motor 500. The inverter 400 is electrically connected to the hybrid ECU 300, and the operation is controlled by the hybrid ECU 300.

  The motor 500 includes a rotor having a plurality of permanent magnets on the outer peripheral surface, and a stator around which a three-phase coil that forms a rotating magnetic field is wound (not shown). It is an example. An output shaft (not shown) of the motor 500 is configured as a rotation shaft concentric with the crankshaft of the engine 200, and the output of the motor 500 is configured to function as a power source of the hybrid vehicle 20, similar to the engine 200. Yes. The hybrid system 10 is configured so that the output of the motor 500 can be applied to a later-described piston 203 in the engine 200 via the crankshaft 205. That is, the motor 500 is an example of the “driving force applying means” according to the present invention.

  Note that the electrical, physical, and mechanical interrelationships between the motor 500 and the engine 200 are not limited to those of the present embodiment. For example, the output of the motor 500 may be transmitted to the crankshaft 205 or the axle via an appropriate gear mechanism. Further, the electric motor according to the present invention may be a so-called motor generator having a function as a generator, and may generate power using a part of the output of the engine 200 during a part of the operation period. . Alternatively, the engine 200 and two types of motor generators may be connected to each other via a planetary gear mechanism, and the hybrid vehicle 20 may be driven while appropriately inputting / outputting their power.

  The battery 600 is a storage battery that functions as a power supply source for driving the motor 500. The battery 600 is electrically connected to the hybrid ECU 300. For example, the SOC of the battery 600 obtained through an SOC (State Of Charge) sensor, a temperature sensor (both not shown), etc. Various battery information such as temperature is output to the hybrid ECU 300.

<1-1-2: Detailed configuration of engine>
Next, with reference to FIG. 2, the detailed structure of the engine 200 will be described together with its basic operation. FIG. 2 is a half sectional system diagram of the engine 200.

  In FIG. 2, the engine 200 causes the air-fuel mixture to explode in the cylinder 201 by the spark plug 202 and converts the reciprocating motion of the piston 203 generated according to the explosive force into the rotational motion of the crankshaft 205 via the connection rod 204. It is configured to be able to. Below, the principal part structure of the engine 200 is demonstrated with a part of the operation | movement. Since engine 200 is a four-cylinder engine as described above, there are originally four cylinders 201 (in this embodiment, for convenience, they are referred to as the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder). However, individual illustrations are omitted for the purpose of preventing complication of explanation.

  When the fuel is burned in the cylinder 201, the air sucked from the outside passes through the intake pipe 206 and is mixed with the fuel injected from the injector 207 to become the above-mentioned air-fuel mixture. Fuel is supplied to the injector 207 from the fuel tank 223, and the injector 207 is configured to be able to inject the supplied fuel into the intake pipe 206 under the control of the engine ECU 100.

  The fuel tank 223 is provided with a fuel sensor 225 for detecting the remaining amount of fuel. In addition, a fuel filter 224 for filtering fuel is installed on a delivery pipe that connects the fuel tank 223 and the injector 207.

  The communication state between the inside of the cylinder 201 and the intake pipe 206 is controlled by opening and closing the intake valve 208. The air-fuel mixture burned inside the cylinder 201 becomes exhaust gas, passes through an exhaust valve 209 that opens and closes in conjunction with opening and closing of the intake valve 208, and is exhausted through an exhaust pipe 210.

  A cleaner 211 is disposed on the intake pipe 206 to purify air sucked from the outside. An air flow meter 212 is disposed on the downstream side (cylinder side) of the cleaner 211. The air flow meter 212 has a form called a hot wire type, and is configured to be able to directly measure the mass flow rate of the inhaled air. The intake pipe 206 is further provided with an intake air temperature sensor 213 for detecting the temperature of the intake air.

  A throttle valve 214 that adjusts the amount of intake air into the cylinder 201 is disposed downstream of the air flow meter 212 in the intake pipe 206. A throttle position sensor 215 is electrically connected to the throttle valve 214, and its opening degree can be detected. On the other hand, the depression amount of the accelerator pedal 226 by the driver is detected by the accelerator position sensor 216 and is grasped by the engine ECU 100. The engine ECU 100 is configured to control the throttle valve motor 217 based on the depression amount of the accelerator pedal 226, and the throttle valve 214 is driven by the throttle valve motor 217.

  A crank position sensor 218 that detects the rotational position of the crankshaft 205 is provided in the vicinity of the crankshaft 205. The crank position sensor 218 is electrically connected to the engine ECU 100, and the engine ECU 100 acquires the position of the piston 203 based on the rotational position of the crankshaft 205 detected by the crank position sensor 218, and The ignition timing and the opening / closing timing of the intake valve 208 and the exhaust valve 209 can be controlled. The engine ECU 100 is configured to be able to calculate the engine speed Ne of the engine 200 based on the rotational position of the crankshaft 205.

  The cylinder block that houses the cylinder 201 is provided with a knock sensor 219 that can measure the knock strength of the engine 200. The water jacket in the cylinder block detects the coolant temperature of the engine 200. The water temperature sensor 220 is disposed.

  A three-way catalyst 222 is installed in the exhaust pipe 210. The three-way catalyst 222 is a catalyst capable of purifying CO (carbon monoxide), HC (hydrocarbon), and NOx (nitrogen oxide) discharged from the engine 200, respectively. An air-fuel ratio sensor 221 is disposed upstream of the three-way catalyst 222 in the exhaust pipe 210. The air-fuel ratio sensor 221 is configured to be able to detect the air-fuel ratio of the engine 200 from the exhaust gas discharged from the exhaust pipe 210.

<1-2: Operation of Embodiment>
<1-2-1: Overview of catalyst warm-up control>
In the engine 200, when the three-way catalyst 222 has not reached the catalyst activation temperature, the three-way catalyst 222 does not act effectively, and thus catalyst warm-up control for warming up the three-way catalyst 222 is executed. Whether or not the catalyst warm-up control is to be executed is determined by the engine ECU 100 acquiring the coolant temperature of the engine 200 via the coolant temperature sensor 220 and determining whether or not the coolant temperature is equal to or less than (or less than) a predetermined value. Is done. The period during which the catalyst warm-up control is executed is an example of the “warm-up period” according to the present invention, but the criterion for determining whether to perform the catalyst warm-up control is limited to, for example, the cooling water temperature. For example, outside air temperature, catalyst temperature, etc. may be sufficient. As a more practical aspect, the catalyst warm-up control may be set to be executed when the engine 200 is started.

  In the present embodiment, at the time of catalyst warm-up control, the ignition timing of the spark plug 202 (that is, the piston position to be ignited) is delayed with respect to the reference timing. Needless to say, the reference time is set individually and specifically in view of the specifications, performance, environmental conditions, and the like of the engine 200. Therefore, the exact ignition timing (ignition position or ignition crank angle) when the ignition timing is retarded in this way is not uniquely defined. Since the exhaust temperature rises, the temperature of the three-way catalyst 222 installed in the exhaust pipe 210 is promoted.

  On the other hand, when the ignition timing is retarded, the ignition timing is generally set within an expansion stroke that exceeds the compression TDC. However, if the retard amount of the ignition timing is set too large, the combustion process may not be completed within the expansion stroke, and the combustion stability such as the occurrence of a misfire cycle may be deteriorated. Has its limits.

  In order to cope with such a problem, in the present embodiment, it is possible to effectively warm up the three-way catalyst 222 by controlling the piston speed of each cylinder in the engine 200 during the catalyst warm-up control. .

<1-2-2: Piston speed control>
Here, with reference to FIG. 3, the detail of the control aspect of the piston degree which concerns on this embodiment is demonstrated. FIG. 3 is a stroke table at the time of catalyst warm-up control of each cylinder constituting the engine 200.

  In FIG. 3, the stroke contents of each of the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder are shown in a horizontal series in association with the crank angle. The engine 200 is a four-cylinder four-cycle engine, and each stroke is sequentially repeated every 180 ° crank angle defined by TDC and BDC. In FIG. 3, the compression TDC at the end of the compression stroke in the first cylinder is represented as 0 ° for convenience.

  In FIG. 3, the portion indicated by a white circle represents the ignition timing of each cylinder. In this embodiment, the crank angle obtained by retarding the ignition timing of each cylinder by α ° (α> 0) from the compression TDC in each cylinder, that is, “180 × i + α °” (where i = 0, 1, 2, .., N) is set to the crank position defined by. That is, in the engine 200, the ignition timing is set within the expansion stroke during catalyst warm-up control.

  Here, engine ECU 100 controls hybrid ECU 300 to reduce the piston speed of each cylinder in a part of the expansion stroke by the power of motor 500 through the control of inverter 400. That is, in this case, this is an example of a state in which “driving force is applied in the negative direction of the movement direction of the piston” in the present invention. Such deceleration control of the piston speed is continued to a crank position where the crank angle is “180 × i + β °” (where α <β <180).

  As a result of the deceleration control of the piston in this way, the combustion time of the fuel is sufficiently secured, the combustion stability is improved, and the occurrence of torque fluctuation or the like is suppressed. In addition, since the combustion time can be secured, the ignition timing itself can be further retarded as compared with the case where no such control is performed, and the exhaust temperature can be increased efficiently. That is, warming up of the three-way catalyst 222 is promoted.

  On the other hand, the piston speed is increased from the end position of the deceleration control to the crank position at which the expansion stroke ends. That is, in this case, this is an example of a state in which “a driving force is applied in the positive direction of the movement direction of the piston” in the present invention.

  As a result of speed-up control of the piston in this way, the discharge of unburned fuel is promoted, and afterburning of the unburned fuel in the exhaust pipe 210 is promoted. As a result, the exhaust temperature is efficiently raised, and warming up of the three-way catalyst 222 is promoted.

  Here, further details of such piston speed control will be described with reference to FIG. FIG. 4 is a timing chart in one cylinder based on the stroke table of FIG. In the figure, the same reference numerals are given to the same portions as those in FIG. 3, and the description thereof will be omitted as appropriate.

  In FIG. 4, the expansion stroke to compression TDC and BDC and the exhaust stroke leading to it are shown. The ignition timing Tp is set to a crank position of 0 + α ° as a crank angle as described above. Here, in this embodiment, the value β that defines the switching timing Tc between the deceleration control and the acceleration control of the piston 203 is set to α + 90 °, and the piston deceleration period ΔTd that represents the period during which the piston is subjected to deceleration control. Has a crank angle of 90 °. That is, the piston deceleration period ΔTd is an example of “at least part of the expansion stroke including the vicinity of the piston position corresponding to the ignition timing”.

  On the other hand, in the present embodiment, such piston speed control is performed for all cylinders, so that the deceleration and acceleration cycles are completed within the expansion stroke so as not to inhibit similar control for the other cylinders. Set to Accordingly, the Biston acceleration period ΔTi starting from the switching time Tc is set to (90−α) ° as the crank angle. That is, the piston acceleration period ΔTi is an example of “at least part of the expansion stroke including the vicinity of the bottom dead center”.

  The setting mode of the piston deceleration period ΔTd and the piston acceleration period ΔTi shown in the present embodiment is an example. Accordingly, the start position and the end position of the piston deceleration period are not limited as long as it is possible to extend the combustion time in the expansion stroke to some extent as compared with the case where such piston deceleration control is not performed. For example, these positions may be set in advance so that the exhaust temperature can be effectively increased experimentally, empirically, or based on simulations.

  Similarly, the start position and the end position of the piston acceleration period are not limited as long as the exhaust of the unburned fuel can be promoted to some extent as compared with the case where no piston acceleration control is performed. For example, these positions may be set in advance so that afterburning of the unburned fuel can be effectively performed experimentally, empirically, or based on simulation.

  As described above, according to the hybrid system 10 according to the present embodiment, the motor 500 that is one of the power sources is used, and the piston speed of each cylinder is set to the positive direction of the movement direction via the crankshaft 205. The engine 200, in particular, the three-way catalyst 222, can be effectively warmed up by appropriately variably controlling in the negative direction and accelerating and decelerating the piston.

<2: Second Embodiment>
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 5 is another stroke table during the catalyst warm-up control of each cylinder constituting the engine 200. In the figure, the same reference numerals are given to the same portions as those in FIG. 3, and the description thereof will be omitted as appropriate.

  In FIG. 5, at the time of starting the engine 200 (that is, an example of the “warm-up period” according to the present invention), the air-fuel ratio of the first cylinder and the fourth cylinder is lower than the stoichiometric air-fuel ratio (that is, The air-fuel ratio of the second cylinder and the third cylinder is higher than the stoichiometric air-fuel ratio (that is, the “lean-side air-fuel ratio” according to the present invention). An example of “fuel ratio” is controlled. At this time, based on the air-fuel ratio detected by the air-fuel ratio sensor 221, the engine ECU 100 fuels injected through the injector 207 so that the overall air-fuel ratio of all cylinders is close to the theoretical air-fuel ratio. Is controlling.

  As described above, in the second embodiment, since the air-fuel ratio at the time of start is different between the first and fourth cylinders and the second and third cylinders, the ignition timing is different between these cylinder groups. That is, since the fuel amount is sufficient in the first and fourth cylinders controlled to the rich side air-fuel ratio, the ignition timing is set in the vicinity of the compression TDC, and the combustion time is relatively shorter in the second and third cylinders. Since it is necessary for a long time, the crank position is set to an advance side of the compression TDC, and early ignition is executed.

  On the other hand, the second and third cylinders controlled to the lean side air-fuel ratio have lower combustion torque than the first and fourth cylinders controlled to the rich side air-fuel ratio, so the output torque is low. The torque difference is likely to occur. Accordingly, there is a case where warm-up is not always effectively performed at the time of start-up as an example of the warm-up period. Therefore, in the present embodiment, the piston speed control is executed for the second and third cylinders set to the lean side air-fuel ratio, and effective warm-up is realized.

  That is, in FIG. 5, in the second and third cylinders, the piston speed is reduced in the piston position range from the ignition timing (within the compression stroke) to the expansion stroke beyond the compression TDC. Accordingly, the combustion time in the second and third cylinders can be secured. Therefore, combustion stability is improved and output torque is improved. That is, the torque difference between the cylinders is reduced, and the torque fluctuation at the start is reduced, so that the engine 200 can be warmed up effectively.

  Here, with reference to FIG. 6, the detail of the speed control of the piston which concerns on 2nd Embodiment is demonstrated. FIG. 6 is a timing chart of the cylinder corresponding to the lean side air-fuel ratio in the stroke table of FIG. In the figure, the same reference numerals are assigned to the same parts as those in FIG.

  In FIG. 6, the deceleration period ΔTd is set as a range from the piston position corresponding to the ignition timing to a crank angle of 90 °. In this deceleration period ΔTd, the piston deceleration control is performed, and the flame growth time is secured. As is apparent from FIG. 6, in this embodiment, the deceleration period of the piston is set over two strokes. Therefore, the order in the process is set such that the cylinders whose pistons are controlled to decelerate, such as the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder, are not adjacent to each other.

  In the first and fourth cylinders set to the rich side air-fuel ratio, combined control of deceleration and acceleration according to the first embodiment may be executed. In this case, the effect of increasing the exhaust temperature can be obtained, and the engine 200 can be warmed up more effectively.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and the control of the internal combustion engine accompanying such a change. The apparatus is also included in the technical scope of the present invention.

It is a mimetic diagram of a hybrid system concerning one embodiment of the present invention. FIG. 2 is a half sectional system diagram of an engine in the hybrid system of FIG. 1. 3 is a stroke table of each cylinder when the catalyst of the engine of FIG. 2 is warmed up. FIG. 4 is a timing chart in one cylinder based on the stroke table of FIG. 3. It is a stroke table of each cylinder concerning a 2nd embodiment of the present invention. 6 is a timing chart in a cylinder set to a lean air-fuel ratio in FIG. 5.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Hybrid system, 100 ... Engine ECU, 200 ... Engine, 201 ... Cylinder, 202 ... Spark plug, 203 ... Piston, 220 ... Water temperature sensor, 222 ... Three-way catalyst, 300 ... Hybrid ECU, 400 ... Inverter, 500 ... Motor 600 ... Battery.

Claims (7)

A control device for an internal combustion engine for controlling the internal combustion engine in a vehicle having an internal combustion engine having a piston and a crankshaft connected to the piston as at least a part of a power source,
Driving force applying means capable of applying a driving force to the piston;
The driving force is applied to the piston in at least one of a positive direction and a negative direction of the movement in at least a part of a warm-up period defined as a period in which at least a part of the internal combustion engine is to be warmed up. And a driving force control means for controlling the driving force applying means. Further comprising warming-up means for warming up at least a part of the internal combustion engine by retarding the ignition timing of the internal combustion engine with respect to a predetermined reference time;
2. The control device for an internal combustion engine according to claim 1, wherein the driving force control unit applies the driving force in a period in which the ignition timing is retarded as at least a part of the warm-up period. The warm-up means retards the ignition timing so that the ignition timing is within the expansion stroke of the internal combustion engine,
The driving force control means includes at least a vicinity of a position of the piston corresponding to the ignition timing in a range defined by a position of the piston corresponding to the ignition timing and a bottom dead center of the internal combustion engine in the expansion stroke. The control device for an internal combustion engine according to claim 2, wherein the driving force is applied so that the speed of the piston decreases in a part of the range. The driving force control means controls the driving force application means so that the speed of the piston increases in at least a part of the expansion stroke of the internal combustion engine including the vicinity of bottom dead center. The control device for an internal combustion engine according to any one of claims 3 to 4. The internal combustion engine includes: (i) a plurality of cylinders each including the piston; and (ii) a fuel supply unit that supplies fuel to each of the plurality of cylinders.
The control device for the internal combustion engine has a theoretical air-fuel ratio in each of the cylinders in the plurality of cylinders and in other cylinders excluding the cylinders in the start-up period defined as at least a part of the warm-up period. Further comprising a supply control means for controlling the fuel supply means so that the lean air-fuel ratio is higher than the air-fuel ratio and the rich air-fuel ratio is lower than the stoichiometric air-fuel ratio;
The driving force control means controls the driving force application means so that the speed of the piston is reduced in at least a part of an expansion stroke in a cylinder in which the air-fuel ratio is set to a lean air-fuel ratio. The control device for an internal combustion engine according to any one of claims 1 to 4. The driving force applying means includes an electric motor that applies the driving force to the piston via the crankshaft and functions as a part of a power source of the vehicle together with the internal combustion engine. The control apparatus for an internal combustion engine according to any one of claims 5 to 6. The control device for an internal combustion engine according to any one of claims 1 to 6, wherein at least a part of the internal combustion engine includes a catalyst installed in an exhaust path of the internal combustion engine.

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