JP2013133765A - Automobile engine controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further promote a temperature rise of engine cooling water in a low-revolution-speed operational region particularly at low and medium load.SOLUTION: Under the condition that an operational status of an engine 1 is in an operational region of a low-rotation-speed side and further the cooling water temperature is lower than a given temperature, a controller (PCM 10) controls a fuel injection valve (an injector 18) so as to carry out a subsequent-stage injection subsequently to a main injection in order to give rise to a latter-stage combustion during an expansion stroke subsequently to a principal combustion in a first region on a low-load side. Then, the controller opens twice an exhaust valve by an exhaust valve twice opening means (VVM 71), while in a second region adjacent to a high-load side in relation to the first region, the controller performs latter-stage injection after the main injection and stops opening twice the exhaust valve by the exhaust valve twice opening means.

Description

  The technology disclosed herein relates to a control device for an automobile engine.

  In Patent Document 1, in an automobile equipped with a heater for passenger compartment heating to which cooling water after passing through a spark ignition engine is supplied, the operating state of the engine is in a region of low load and low rotation. It is described that a negative overlap period is provided in which both the intake valve and the exhaust valve are closed when the temperature of the cooling water is difficult to rise. As a result, relatively high-temperature burned gas remains in the cylinder, which increases the compression end temperature, so the amount of cooling water received increases, the cooling water temperature rises quickly, and the heater requirement is satisfied early. It becomes possible.

JP 2009-127428 A

  Although the technique described in the above-mentioned Patent Document 1 tries to increase the heat radiation amount through the cylinder wall surface by leaving the burned gas in the cylinder and thereby increasing the compression end temperature, the temperature of the cooling water There is room for improvement in further promoting the rise.

  The technology disclosed herein has been made in view of such a point, and the object is to further promote the temperature increase of engine cooling water, particularly in a low-medium load and low-speed operation region. .

  An automobile engine control device disclosed herein includes an engine having a cylinder, a cooling water passage provided around an exhaust port connected to the cylinder, and cooling after receiving heat by passing through the cooling water passage. An exhaust stroke is provided with a heater for vehicle compartment heating to which water is supplied, a fuel injection valve configured to inject fuel directly into the cylinder, and an exhaust valve provided at an opening of the cylinder and the exhaust port. And an exhaust double opening means configured to open the exhaust twice to be opened in each of the intake strokes, and a control configured to operate the engine through control of the fuel injection valve and the exhaust double open means A vessel.

  The controller is configured to perform main combustion in the first region on the low load side when the operation state of the engine is in the operation region on the low rotation side and the temperature of the cooling water is equal to or lower than a predetermined temperature. Subsequently, the fuel injection valve is controlled to execute the post-stage injection after the main injection so that the post-stage combustion during the expansion stroke occurs, and the exhaust double-opening means opens the exhaust twice, In the second region adjacent to the high load side with respect to the first region, the fuel injection valve is controlled to execute the post-stage injection after the main injection, and the exhaust double opening by the exhaust double opening means is performed. Stop.

  According to this configuration, when the operating state of the engine is in the low rotation side operation region and in the low load side first region, in other words, in the operation region in which the temperature of the cooling water is difficult to rise, When the temperature is equal to or lower than the predetermined temperature, the post injection is executed after the main injection and the exhaust is opened twice. This “predetermined temperature” may be, for example, a temperature required when heating the vehicle interior using the heater, and specifically, may be around 60 ° C. or around 60 ° C. Execution of the post-stage injection follows the main combustion, and post-stage combustion occurs in the expansion stroke, so that the temperature of the burned gas discharged from the exhaust port becomes high. In this way, the temperature difference between the temperature of the burned gas passing through the exhaust port and the cooling water flowing through the cooling water passage provided around the exhaust port becomes large, so heat exchange is performed efficiently here, This is advantageous for increasing the temperature of the cooling water.

  Further, when the engine operating state is in the first region, the burned gas once discharged to the exhaust port is returned again into the cylinder by opening the exhaust twice. Also when the burned gas returns, heat exchange is performed in the cooling water passage provided around the exhaust port, which is further advantageous in increasing the temperature of the cooling water. In particular, the throat portion of the exhaust valve has the highest heat exchange efficiency because of the highest flow velocity, but the burned gas passes through the throat portion twice by opening the exhaust twice, so the temperature of the cooling water It is extremely advantageous for the rise.

  Further, as the burned gas is introduced into the cylinder by opening the exhaust twice, the intake air amount is reduced accordingly. As a result, the amount of working gas in the cylinder is reduced, and the temperature of the gas after combustion is further increased. This is also advantageous for increasing the temperature of the cooling water.

  On the other hand, in the second region where the engine load is higher than that in the first region, the fuel injection amount increases. Therefore, as described above, the intake amount (that is, the fresh air amount) is reduced by opening the exhaust twice. There is a possibility that the exhaust emission performance may be deteriorated due to lack of air. Therefore, in the second region, the main injection and the post-injection are executed, but the exhaust twice opening is stopped. This will increase the temperature of the burnt gas discharged to the exhaust port and promote the temperature rise of the cooling water by the latter stage combustion, while reducing the exhaust emission performance by stopping the double opening of the exhaust. Is avoided.

  In this way, when the cooling water temperature is below the predetermined temperature in the low rotation side region, the temperature rise of the cooling water is effectively promoted, and as a result, when there is a request for heating the passenger compartment, it is satisfied early. It becomes possible to make it.

  An exhaust manifold portion that collects exhaust ports of the plurality of cylinders is formed in the cylinder head of the engine, and the cooling water passage may be provided around the exhaust manifold portion. .

  In this way, the cooling water can further receive the heat of the burned gas on the exhaust side of the engine, so that the above-described post-injection and post-combustion are executed or the exhaust is opened twice. The temperature increase of the cooling water is further promoted.

  The exhaust double opening means is configured to be driven by a hydraulic pressure boosted by the driving force of the engine, and when the exhaust double opening means is operated in the first region, the hydraulic pressure is set high, The hydraulic pressure may be set low when stopping the exhaust double opening means in the second region.

  When the exhaust double opening means is operated, the driving force of the engine must be increased in order to increase the hydraulic pressure, and the temperature of the burned gas increases as the engine load increases. This is further advantageous in increasing the temperature of the cooling water when the engine operating state is in the first region.

  The turbocharger may further include a turbine disposed in the exhaust passage of the engine and a compressor disposed in the intake passage.

  When the exhaust is opened twice, the exhaust energy is reduced by that amount, so the supercharging pressure by the turbocharger becomes low. This reduces the amount of intake air in the first region where the exhaust is opened twice, which is advantageous in increasing the temperature of the burned gas as described above, and further increases in the temperature of the cooling water. Promoted.

  The engine may be a compression self-ignition engine having a geometric compression ratio set to less than 16.

  A compression self-ignition engine having a low geometric compression ratio has a relatively low combustion temperature in the first place, which is disadvantageous for increasing the temperature of cooling water. Accordingly, the heating performance of the vehicle interior in the first region and the second region on the low rotation side is disadvantageous. As described above, the cooling water is increased by performing the rear injection and the rear combustion or the exhaust twice opening. By promoting the temperature, the heating performance of the passenger compartment is improved.

  As described above, according to the above-described automotive engine control device, when the operating state of the engine is in the first region of low rotation and low load, the combination of the execution of the post-stage injection and the post-stage combustion and the double opening of the exhaust is combined. Thus, the temperature of the cooling water can be effectively increased. In addition, when in the second region where the load is higher than that in the first region, the second opening of the exhaust is stopped while performing the latter-stage injection and the second-stage combustion, thereby avoiding the deterioration of the exhaust emission performance and cooling. The temperature of water can be increased effectively. As a result, when there is a request for heating the passenger compartment, it can be satisfied quickly.

It is the schematic which shows the structure of a diesel engine. It is a block diagram concerning control of a diesel engine. It is explanatory drawing which illustrates the structure of the cylinder head of a diesel engine. It is a figure which shows an example of the driving | running map of a diesel engine. It is an example of the fuel-injection aspect in a 1st and 2nd area | region. (A) outside air temperature, (b) water temperature, (c) engine speed, (d) engine load, (e) operating state with double exhaust opening, (f) hydraulic pressure state near the first and second regions (G) It is a time chart which shows an example of each change of the execution state of back | latter stage injection.

  Hereinafter, the diesel engine which concerns on embodiment is demonstrated based on drawing. The following description of the preferred embodiment is merely exemplary in nature. 1 and 2 show a schematic configuration of an engine (engine body) 1 according to the embodiment. The engine 1 is a diesel engine that is mounted on a vehicle and is supplied with fuel mainly composed of light oil.

  The engine 1 includes a cylinder block 11 provided with a plurality of cylinders 11a (only one is shown), a cylinder head 12 provided on the cylinder block 11, and a lower side of the cylinder block 11, and is lubricated. And an oil pan 13 in which oil is stored. In each cylinder 11a of the engine 1, a piston 14 is fitted and removably fitted. A top surface of the piston 14 is formed with a cavity defining a reentrant combustion chamber 14a. The piston 14 is connected to the crankshaft 15 via a connecting rod 14b.

  In the cylinder head 12, an intake port 16 and an exhaust port 17 are formed for each cylinder 11a, and an intake valve 21 and an exhaust valve that open and close the opening of the intake port 16 and the exhaust port 17 on the combustion chamber 14a side. 22 are arranged respectively.

  In the valve systems that drive these intake and exhaust valves 21 and 22, respectively, a hydraulically operated variable mechanism that switches the operation mode of the exhaust valve 22 between a normal mode and a special mode on the exhaust valve side (see FIG. 2 below). VVM (Variable Valve Motion). Although detailed illustration of the configuration of the VVM 71 is omitted, two types of cams having different cam profiles, a first cam having one cam peak and a second cam having two cam peaks, and the first cam A lost motion mechanism that selectively transmits the operating state of one of the first and second cams to the exhaust valve 22 is configured to transmit the operating state of the first cam to the exhaust valve 22. In some cases, the exhaust valve 22 operates in a normal mode that is opened only once during the exhaust stroke, whereas when the operating state of the second cam is transmitted to the exhaust valve 22, the exhaust valve 22 is in the exhaust stroke. It operates in a special mode in which the valve is opened twice, and so-called exhaust is opened twice.

  Switching between the normal mode and the special mode of the VVM 71 is performed by hydraulic pressure supplied from an engine-driven hydraulic pump (not shown), and the special mode is used in the control related to the internal EGR. In order to enable switching between the normal mode and the special mode, an electromagnetically driven valve system that drives the exhaust valve 22 by an electromagnetic actuator may be employed. The internal EGR control by the VVM 71 is performed mainly when the engine 1 with low fuel ignitability is cold.

  The cylinder head 12 is provided with an injector 18 for injecting fuel, and a glow plug 19 for warming the intake air in each cylinder 11a to improve the ignitability of the fuel when the engine 1 is cold. The injector 18 is arranged so that its fuel injection port faces the combustion chamber 14a from the ceiling surface of the combustion chamber 14a. Basically, fuel is directly supplied to the combustion chamber 14a near the top dead center of the compression stroke. The injection is supplied.

  An intake passage 30 is connected to one side of the engine 1 so as to communicate with the intake port 16 of each cylinder 11a. On the other hand, an exhaust passage 40 for discharging burned gas (that is, exhaust gas) from the combustion chamber 14a of each cylinder 11a is connected to the other side of the engine 1. In the intake passage 30 and the exhaust passage 40, as will be described in detail later, a large turbocharger 61 and a small turbocharger 62 for supercharging intake air are disposed.

  An air cleaner 31 that filters intake air is disposed at the upstream end of the intake passage 30. On the other hand, a surge tank 33 is disposed near the downstream end of the intake passage 30. The intake passage 30 downstream of the surge tank 33 is an independent passage branched for each cylinder 11a, and the downstream end of each independent passage is connected to the intake port 16 of each cylinder 11a.

  Between the air cleaner 31 and the surge tank 33 in the intake passage 30, compressors 61a and 62a of large and small turbochargers 61 and 62, and an intercooler 35 that cools the air compressed by the compressors 61a and 62a, A throttle valve 36 is provided for adjusting the amount of intake air into the combustion chamber 14a of each cylinder 11a. The throttle valve 36 is basically fully opened, but is fully closed when the engine 1 is stopped so that no shock is generated.

  The upstream portion of the exhaust passage 40 is constituted by an exhaust manifold having an independent passage branched for each cylinder 11a and connected to the outer end of the exhaust port 17 and a collecting portion where the independent passages gather. Yes. In the engine 1, the exhaust manifold 37 is formed in the cylinder head 12 as shown in FIG. 3. 3 shows only a part thereof, a water jacket 371 through which cooling water flows is formed around the exhaust port and the exhaust manifold 37 in the cylinder head 12. That is, the engine 1 employs a water-cooled exhaust manifold structure. The exhaust manifold 37 may not be formed in the cylinder head 12, but may be configured to be externally attached to the cylinder head 12, and a cooling water passage may be provided in the external exhaust manifold.

  To the downstream side of the exhaust manifold 37 in the exhaust passage 40, the turbine 62b of the small turbocharger 62, the turbine 61b of the large turbocharger 61, and harmful components in the exhaust gas are purified in order from the upstream side. An exhaust purification device 41 and a silencer 42 are provided.

The exhaust purification device 41 includes an oxidation catalyst 41a and a diesel particulate filter (hereinafter referred to as a filter) 41b, which are arranged in this order from the upstream side. The oxidation catalyst 41a and the filter 41b are accommodated in one case. The oxidation catalyst 41a has an oxidation catalyst carrying platinum or platinum added with palladium or the like, and promotes a reaction in which CO and HC in the exhaust gas are oxidized to produce CO ₂ and H ₂ O. Is. The filter 41b collects particulates such as soot contained in the exhaust gas of the engine 1. The filter 41b may be coated with an oxidation catalyst. As will be described later, the engine 1 greatly reduces or eliminates the production of RawNOx by reducing the compression ratio, and omits a catalyst for NOx treatment.

  A portion of the intake passage 30 between the surge tank 33 and the throttle valve 36 (that is, a portion downstream of the small compressor 62a of the small turbocharger 62), the exhaust manifold 37 and the small turbo in the exhaust passage 40. The portion between the supercharger 62 and the small turbine 62b (that is, the portion upstream of the small turbocharger 62b of the small turbocharger 62) is an exhaust gas for returning a part of the exhaust gas to the intake passage 30. They are connected by a reflux passage 51. The exhaust gas recirculation passage 51 is provided with an exhaust gas recirculation valve 51a for adjusting the recirculation amount of the exhaust gas to the intake passage 30 and an EGR cooler 52 for cooling the exhaust gas with engine cooling water. Yes.

  The large turbocharger 61 has a large compressor 61 a disposed in the intake passage 30 and a large turbine 61 b disposed in the exhaust passage 40. The large compressor 61 a is disposed between the air cleaner 31 and the intercooler 35 in the intake passage 30. On the other hand, the large turbine 61b is disposed between the exhaust manifold and the oxidation catalyst 41a in the exhaust passage 40.

  The small turbocharger 62 has a small compressor 62 a disposed in the intake passage 30 and a small turbine 62 b disposed in the exhaust passage 40. The small compressor 62 a is disposed on the downstream side of the large compressor 61 a in the intake passage 30. On the other hand, the small turbine 62 b is disposed on the upstream side of the large turbine 61 b in the exhaust passage 40.

  That is, in the intake passage 30, a large compressor 61a and a small compressor 62a are arranged in series from the upstream side, and in the exhaust passage 40, a small turbine 62b and a large turbine 61b are arranged in series from the upstream side. Has been. The large and small turbines 61b and 62b are rotated by the exhaust gas flow, and the large and small turbines 61a and 62a connected to the large and small turbines 61b and 62b are rotated by the rotation of the large and small turbines 61b and 62b, respectively. Each operates.

  The small turbocharger 62 is relatively small, and the large turbocharger 61 is relatively large. That is, the large turbine 61 b of the large turbocharger 61 has a larger inertia than the small turbine 62 b of the small turbocharger 62.

  A small intake bypass passage 63 that bypasses the small compressor 62 a is connected to the intake passage 30. The small intake bypass passage 63 is provided with a small intake bypass valve 63 a for adjusting the amount of air flowing to the small intake bypass passage 63. The small intake bypass valve 63a is configured to be in a fully closed state (that is, normally closed) when no power is supplied.

  On the other hand, the exhaust passage 40 is connected to a small exhaust bypass passage 64 that bypasses the small turbine 62b and a large exhaust bypass passage 65 that bypasses the large turbine 61b. The small exhaust bypass passage 64 is provided with a regulating valve 64a for adjusting the exhaust amount flowing to the small exhaust bypass passage 64, and the large exhaust bypass passage 65 has an exhaust amount flowing to the large exhaust bypass passage 65. A wastegate valve 65a for adjusting the pressure is provided. Both the regulating valve 64a and the waste gate valve 65a are configured to be in a fully open state (that is, normally open) when no power is supplied.

  The large turbocharger 61 and the small turbocharger 62 are integrated into a single unit including the intake passage 30 and the exhaust passage 40 in which the large turbocharger 61 and the small turbocharger 62 are arranged, thereby forming a supercharger unit 60. doing. The supercharger unit 60 is attached to the engine 1.

  Although a detailed configuration diagram is omitted, as shown in FIG. 1, the engine 1 passes through the cooling water circulation circuit of the engine 1 (the water jacket 371 provided on the exhaust side of the engine 1 described above). A heater 8 to which a part of the cooling water (passed through) is supplied is provided. The heater 8 is a heat exchanger for heating the passenger compartment, and the cooling water after heat exchange with air in the heater 8 is configured to return to the engine 1.

The diesel engine 1 configured as described above is controlled by a powertrain control module (hereinafter referred to as PCM) 10. The PCM 10 includes a microprocessor having a CPU, a memory, a counter timer group, an interface, and a path connecting these units. This PCM 10 constitutes a controller. As shown in FIG. 2, the PCM 10 includes a water temperature sensor SW1 that detects the temperature of the engine cooling water, a supercharging pressure sensor SW2 that is attached to the surge tank 33 and detects the pressure of the air supplied to the combustion chamber 14a, An intake air temperature sensor SW3 that detects the temperature of the intake air, a crank angle sensor SW4 that detects the rotation angle of the crankshaft 15, and an accelerator opening sensor that detects an accelerator opening corresponding to an operation amount of an accelerator pedal (not shown) of the vehicle. Detection signals of SW5, an O ₂ sensor SW6 for detecting the oxygen concentration in the exhaust gas, and an exhaust pressure sensor SW7 for detecting the exhaust pressure upstream of the small turbine 62b are input, and various detection signals are generated based on these detection signals. The state of the engine 1 and the vehicle is determined by performing calculations, and the injector 18 and the glow plug 19 are correspondingly determined. , Control signals are output to the VVM 71 of the valve operating system and the actuators of the various valves 36 and 51a.

  The PCM 10 controls the operation of the large and small turbochargers 61 and 62 when the engine is operating. Specifically, the PCM 10 controls the openings of the small intake bypass valve 63a, the regulate valve 64a, and the wastegate valve 65a so as to become the target boost pressure set according to the operating state of the engine 1. . Specifically, in the region on the low rotation side, the small intake bypass valve 63a and the regulating valve 64a are set to an opening other than fully opened, and the wastegate valve 65a is fully closed, so that only the small turbocharger 62 or Activating both the large and small turbochargers 61, 62. On the other hand, in the region on the high speed side, the small turbocharger 62 becomes over-rotated and exhaust resistance is generated, so the small intake bypass valve 63a and the regulating valve 64a are fully opened and the wastegate valve 65a is fully closed. By setting the opening close to the state, the small turbocharger 62 is bypassed and only the large turbocharger 61 is operated. The waste gate valve 65a is set slightly open to prevent the large turbocharger 61 from over-rotating.

  Thus, the engine 1 is configured to have a relatively low compression ratio with a geometric compression ratio of 12 or more and less than 16 (for example, 14), thereby improving exhaust emission performance and thermal efficiency. It is trying to improve.

(Outline of engine combustion control)
The basic control of the engine 1 by the PCM 10 mainly determines a target torque (in other words, a target load) based on the accelerator opening, and the fuel injection amount and injection timing corresponding to the target torque are determined by the injector 18. This is realized by operation control. The target torque is set so as to increase as the accelerator opening increases and the engine speed increases, and the fuel injection amount is set based on the target torque and the engine speed. The injection amount is set to increase as the target torque increases and as the engine speed increases. Further, the recirculation ratio of the exhaust gas into the cylinder 11a is controlled by controlling the opening degree of the throttle valve 36 and the exhaust gas recirculation valve 51a (that is, external EGR control) or by controlling the VVM 71 (that is, internal EGR control). .

  Further, the PCM 10 sets the target boost pressure according to the operating state of the engine 1 at the time of steady operation, and adjusts the opening degree of the regulating valve 64a and the wastegate valve 65a so that the target boost pressure is achieved. And supercharging pressure feedback control for controlling opening and closing of the small intake bypass valve 63a.

  The engine 1 is basically configured to operate lean so that the excess air ratio λ ≧ 2.4 or more in order to eliminate or suppress the generation of RawNOx.

(Cooling water temperature increase control)
As described above, the engine 1 is set to have a low geometric compression ratio and a lean air excess ratio λ ≧ 2.4, so that the combustion temperature is relatively low and the cooling loss is low. There are relatively few. This is a disadvantageous configuration for raising the temperature of the cooling water when the temperature is low. In particular, the operating state of the engine 1 is in a low rotation and low load region under conditions where the outside air temperature is low (for example, 0 ° C. or lower) and the engine water temperature is low (for example, 60 ° C. or lower). Sometimes the temperature of the cooling water becomes more difficult to rise. This means that low-temperature cooling water is supplied to the heater 8, and there is a problem that the heating performance in the passenger compartment is lowered.

  Therefore, in this engine system, when the engine is cold and the operation state is in an operation region of low rotation and low load, the cooling water temperature increase promotion control that promotes the temperature rise of the cooling water is executed.

  First, FIG. 4 shows an example of an operation map when the engine 1 is cold. The area (A) in the figure is an area on the low speed side, in other words, an area roughly corresponding to the low speed side when the engine speed area is divided into a high speed side and a low speed side. In addition, it is a region corresponding to a low load when the low load region, in other words, the load region of the engine is divided into a high load, a medium load, and a low load. However, the area (A) is an area on the higher rotation side than the predetermined rotation speed (corresponding to the first area).

  On the other hand, the region (B) is a region adjacent to the region (A) on the high load side. Therefore, the region (B) is on the low rotation side in the engine speed region, and includes a part of the low load to medium load in the load region. The region (B) also includes a low load region that is equal to or lower than the predetermined rotational speed (corresponding to the second region).

  In both of the regions (A) and (B), the PCM 10 causes the injector 18 to perform the front injection, the main injection, and the rear injection. FIG. 5 shows an example of the fuel injection mode in the regions (A) and (B). That is, during the compression stroke, a plurality of (three in the illustrated example) pre-stage injections are performed. Although illustration is omitted, the pre-stage injection causes pre-stage combustion in the vicinity of the compression top dead center, which increases the temperature and pressure in the cylinder 18a, and improves the ignitability of the main fuel by the subsequent main injection. In addition, there is no restriction | limiting in particular in the frequency | count of front | former stage injection, What is necessary is just to perform 1 time or more. Further, the front injection may be omitted.

  The main injection is executed to shift to the compression top dead center in the illustrated example. By executing this main injection, main combustion occurs. Then, during the expansion stroke after the main injection, the post-stage injection is executed. In the illustrated example, two subsequent injections are performed, but the number of subsequent injections is not particularly limited. Although the illustration is omitted by the execution of the post-stage injection, the post-stage combustion occurs during the expansion stroke. This post-stage combustion increases the temperature of burned gas discharged from the cylinder 18a.

  Thus, in the region (A), the exhaust is opened twice by the operation of the VVM 71 together with the execution of the post-stage injection. As a result, the exhaust valve 22 is opened again during the intake stroke, and the burned gas is introduced into the cylinder 18a. In this way, in the region (A), the temperature of the burned gas discharged from the cylinder 18a is increased due to the execution of the post-stage injection and the accompanying post-stage combustion. The temperature difference from the cooling water becomes large, which is advantageous for increasing the temperature of the cooling water. Further, in the engine 1, since the water jacket 371 is provided not only around the exhaust port but also around the exhaust manifold 37, the amount of heat received from the burned gas can be further increased.

  Further, by combining the increase in the temperature of the burnt gas to be discharged and the double opening of the exhaust, the high temperature burnt gas once discharged from the cylinder 19a is once again returned into the cylinder. The heat exchange efficiency on the side increases, which is further advantageous for raising the temperature of the cooling water. In particular, since the throat portion of the exhaust valve 22 is the place where the gas flow velocity is highest, the thermal efficiency efficiency of the burned gas and the cooling water is highest at this place. Since the opening of the exhaust twice causes the burned gas to pass through the throat twice, the temperature of the cooling water can be increased even earlier.

  Further, by performing the exhaust twice opening, the exhaust energy supplied to the small turbine 62a on the downstream side is reduced, so that the supercharging pressure by the small turbocharger 62 is also reduced. This reduces the amount of fresh air introduced into the cylinder 18a, so that the temperature of the gas after combustion increases. This is also advantageous for raising the temperature of the cooling water.

  Further, since the VVM 71 that opens the exhaust twice is operated by the engine drive hydraulic pressure as described above, when the VVM 71 is operated and the exhaust is opened twice, the load on the engine 1 increases. This increases the fuel injection amount and raises the exhaust gas temperature, which is also advantageous for raising the temperature of the cooling water.

  On the other hand, since the region (B) is a region having a higher load than the region (A), the fuel injection amount increases accordingly. If the exhaust is opened twice at this time and the amount of fresh air is reduced, the fresh air is insufficient and there is a risk of causing smoke, for example. Therefore, in the region (B), the exhaust twice opening is stopped and only the above-described post-injection and post-combustion are executed. By doing so, it is possible to promote the temperature rise of the cooling water even in the region (B) which is disadvantageous to the temperature rise of the cooling water while avoiding the deterioration of the exhaust emission performance.

  Note that when the temperature of the cooling water of the engine 1 is low and the temperature of the cooling water is required to be raised, the rotational speed of the engine 1 is increased, so that the operating state of the engine 1 automatically becomes the region (A). The exhaust will be opened twice.

  Next, the cooling water temperature increase promotion control in the vicinity of the above-described regions (A) and (B) will be further described with reference to FIG. FIG. 5A shows an example of a change in the outside air temperature, and the cooling water temperature increase promotion control is executed when the outside air temperature is equal to or lower than a predetermined temperature (see the broken line in FIG. 5). The predetermined temperature may be set to 0 ° C., for example. FIG. 2B shows an example of a change in the cooling water temperature, where T1 indicates a lower limit temperature for control and T2 indicates an upper limit temperature for control. That is, when the water temperature is lower than the lower limit temperature T1, for example, the hydraulic pressure does not rise and the VVM 71 cannot be operated, so the cooling water temperature increase control is not performed. Further, when the water temperature is higher than the upper limit temperature T2, the cooling water temperature increase promotion control is unnecessary in the first place. The upper limit temperature T2 may be set to 60 ° C., for example. In the illustrated example, the water temperature exceeds T1 at time 2, and one of the conditions for executing the cooling water temperature increase promotion control is satisfied.

  FIG. 3C shows an example of changes in engine speed. In the figure, N1 indicates the lower limit rotational speed of control, and N2 indicates the upper limit rotational speed of control. When the rotational speed is lower than the lower limit rotational speed N1, the cooling water temperature increase promotion control is not performed. As described above, when the cooling water temperature is low and it is necessary to promote the temperature rise of the cooling water, the rotational speed of the engine 1 is increased from N1. On the other hand, when the rotational speed is higher than the upper limit rotational speed N2, the amount of heat released per unit time increases, so that the cooling water temperature increase promotion control is unnecessary (the regions (A) and (B) in FIG. ). In the illustrated example, the engine speed exceeds N1 at time 1, and one of the conditions for executing the cooling water temperature increase control is satisfied.

  Thus, when the conditions of the water temperature and the engine speed are satisfied, the cooling water temperature increase promotion control is started at time 2. That is, as shown in FIG. 5F, the hydraulic pressure is switched from low (low pressure) to high (high pressure) to operate the VVM 71, and the VVM 71 operates as shown in FIG. . Further, as shown in FIG. 5G, the post-injection execution flag is also turned on, and the post-injection is executed after the main injection. Thus, as described above, the temperature of the burned gas discharged from the cylinder 18a is raised, and the high-temperature burned gas is introduced into the cylinder 18a again by opening the exhaust twice, thereby improving the efficiency of the cooling water. The temperature is increased. As a result, the engine water temperature rises quickly as shown in FIG. Then, if the engine water temperature becomes equal to or higher than the upper limit temperature T2, the cooling water temperature increase promotion control is stopped (see time 5). That is, the post-stage injection is not performed (see (g) in the same figure), and the VVM 71 is stopped (see (e) in the same figure). As the VVM 71 is stopped, the hydraulic pressure is also changed to low (see FIG. 5F). Even when the engine water temperature is lower than the upper limit temperature T2, the cooling water temperature increase promotion control is stopped (interrupted) when the engine speed exceeds the upper limit speed N2 (see time 3 to time 4). This corresponds to the operating state of the engine 1 being out of the region (A) and the region (B) shown in FIG.

  Even if the cooling water temperature once becomes equal to or higher than the upper limit temperature T2, if the cooling water temperature subsequently decreases, the cooling water temperature increase promotion control is started again (see time 6). That is, the hydraulic pressure is switched to high, the VVM 71 is operated, and the post-injection is executed (see (e), (f), and (g) in the figure). Then, if the cooling water temperature becomes equal to or higher than the upper limit temperature T2, the cooling water temperature increase promotion control is stopped (see time 7).

  Further, when the cooling water temperature increase promotion control is started again at time 8, when the engine load exceeds the upper limit load (time 9 and 10), as shown in FIG. Assuming that the state has entered the region (B), the VVM 71 is stopped, and the hydraulic pressure is also lowered accordingly (see FIGS. 4E and 4F). Thereby, generation | occurrence | production of smoke is suppressed. The post-injection continues as it is (see (g) in the figure). Thereby, the temperature rise of the cooling water is continued as it is.

  Then, as shown in FIG. 5A, when the outside air temperature exceeds a predetermined temperature (for example, 0 ° C.) (time 11), the cooling water temperature increase promotion control ends (FIG. 5E). (Refer to (f) and (g)).

  Note that the technology disclosed herein can also be applied to a spark ignition engine (gasoline engine).

1 Diesel engine (engine)
10 PCM (controller)
11a Cylinder 18 Fuel injection valve 22 Exhaust valve 30 Intake passage 37 Exhaust manifold 371 Water jacket (cooling water passage)
40 Exhaust passage 62 Small turbocharger (turbocharger)
62a Small compressor (compressor)
62b Small turbine (turbine)
71 VVM (exhaust double opening means)
8 Heater

Claims (5)

An engine having cylinders;
A cooling water passage provided around an exhaust port connected to the cylinder;
A heater for vehicle compartment heating to which cooling water after receiving heat by passing through the cooling water passage;
A fuel injection valve configured to inject fuel directly into the cylinder;
Exhaust gas double opening means configured to open the exhaust valve provided at the opening of the cylinder and the exhaust port in the exhaust stroke and the intake stroke to open the exhaust twice.
A controller configured to operate the engine through control of the fuel injection valve and the exhaust double opening means, and
The controller is when the operating state of the engine is in an operating region on the low rotation side, and when the temperature of the cooling water is equal to or lower than a predetermined temperature,
In the first region on the low load side, the fuel injection valve is controlled to execute the post-stage injection after the main injection so that the post-stage combustion during the expansion stroke occurs following the main combustion, and the exhaust twice opens. Open the exhaust twice by means,
In the second region adjacent to the high load side with respect to the first region, the fuel injection valve is controlled to execute the post-stage injection after the main injection, and the exhaust double opening means is opened twice. Control device for automobile engine to stop the operation. The control device for an automobile engine according to claim 1,
In the cylinder head of the engine, an exhaust manifold portion that collects exhaust ports of the plurality of cylinders is formed,
The automotive engine control device, wherein the cooling water passage is also provided around the exhaust manifold portion. The control device for an automotive engine according to claim 1 or 2,
The exhaust double opening means is configured to be driven by a hydraulic pressure boosted by the driving force of the engine,
When operating the exhaust double opening means in the first region, the hydraulic pressure is set high, whereas when stopping the exhaust double opening means in the second region, the hydraulic pressure is set low. Engine control device. In the control apparatus of the engine for motor vehicles of any one of Claims 1-3,
A control apparatus for an automobile engine further comprising a turbocharger including a turbine disposed in an exhaust passage of the engine and a compressor disposed in an intake passage. In the control apparatus of the engine for motor vehicles of any one of Claims 1-4,
The engine is a control device for an automobile engine, which is a compression self-ignition engine having a geometric compression ratio set to less than 16.

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