JP2013104400A - Control device of diesel engine with supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an acceleration feeling from deteriorating after a manual transmission 73 is shifted up, in a diesel engine 1 with a supercharger.SOLUTION: A control device of the diesel engine with the superchargers includes a controller 10 which makes at least a first turbo supercharger 62 operate when an operating condition of the diesel engine 1 is in a low-revolution area, and makes a second turbo supercharger 61 operate when the operating condition is in a high-revolution area larger in the number of revolutions than the low-revolution area. The controller 10 performs shift up control for making the first turbo supercharger 62 operate until an accelerator pedal is depressed after the start of a shift up process, when the shift up process, including the full closing of an accelerator, of the manual transmission 73 is performed in the case where the operating condition of the engine is in the high-revolution area.

Description

  The technology disclosed herein relates to a control device for a turbocharged diesel engine.

  For example, as described in Patent Document 1, a small turbocharger having a relatively small turbine and a compressor and a large turbocharger having a relatively large turbine and a compressor are arranged in series. A so-called two-stage turbocharged diesel engine is conventionally known. In this two-stage turbocharged diesel engine, a small turbocharger with a small inertia mainly operates in a low engine speed range where the exhaust flow rate is relatively low, and a predetermined supercharging pressure is secured. On the other hand, in a high rotation range where the exhaust flow rate is relatively high, the large turbocharger operates to ensure a predetermined supercharging pressure. Thus, the diesel engine with a two-stage turbocharger can obtain a desired supercharging pressure in a wider operating region.

  Here, particularly in the diesel engine with a two-stage turbocharger described in Patent Document 1, the shift of the manual transmission including full closure of the accelerator is performed in the operating region where the small turbocharger is operating. When this is done, the exhaust flow velocity decreases and the rotational speed of the small turbocharger decreases. The exhaust flow rate sent to the small turbine is closed by closing both the EGR passage and the exhaust bypass passage bypassing the small turbine. In addition, the intake bypass passage that bypasses the small compressor is fully opened to reduce the resistance imparted to the small compressor, thereby suppressing the decrease in the rotational speed of the small turbocharger. As a result, the turbo lag when the accelerator pedal is depressed after the upshifting process is made as small as possible to enhance the acceleration response.

JP 2005-9314 A

  By the way, when the shift-up operation of the manual transmission is performed, the accelerator is fully closed and the clutch is released, so that the engine is temporarily unloaded. Along with this, the exhaust flow rate is reduced, so the rotational speed of the turbocharger is reduced, and the supercharging pressure is reduced. As a result, when the accelerator pedal is depressed after the completion of the upshift process, the vehicle must be accelerated from a low supercharging pressure state. This exacerbates the acceleration feel.

  Here, in the diesel engine with a two-stage turbocharger, in the operation region where the large turbocharger operates, the turbine of the small turbocharger becomes a resistance, so an exhaust bypass passage that bypasses this is opened. Thus, it is common to stop the operation of the small turbocharger. For example, when shifting up from 3rd speed to 4th speed in fully open acceleration, the upshift process is started in the region where the large turbocharger is operated, and the engine speed after the upshift is It will drop to a low speed near the boundary where the operation of the small turbocharger stops. This means that when the accelerator pedal is depressed after the upshift, the small turbocharger remains inactive and acceleration must be performed only by the operation of the large turbocharger. Large turbochargers have a relatively large inertia, so the number of rotations does not increase easily, and the engine speed decreases immediately after the manual transmission shifts up and the exhaust flow rate is low. As a result, the acceleration feel may be further deteriorated.

  The technology disclosed herein has been made in view of the above points, and the object of the technology is to suppress deterioration of the acceleration feel after the shift up of the manual transmission in a turbocharged diesel engine. is there.

  A control device for a turbocharged diesel engine disclosed herein includes a diesel engine, a first turbine disposed in an exhaust passage of the diesel engine, and a first compressor disposed in an intake passage of the diesel engine. A second turbocharger having a first turbocharger, a second turbine having an inertia larger than the first turbine and disposed in the exhaust passage, and a second compressor disposed in an intake passage of the diesel engine; When the operating state of the turbocharger and the diesel engine is in a low rotation range, at least the first turbocharger is operated, and the operation range of the diesel engine is higher than the low rotation range. A controller configured to operate the second turbocharger when in a high speed region .

  When the engine operating state is in the high speed range and the manual transmission shift-up process including the full closure of the accelerator is performed, the controller may start the accelerator after the start of the shift-up process. Shift-up control for operating the first turbocharger is performed until the pedal is depressed.

  Here, the “low rotation region” may be defined as a region having a lower rotation speed than the predetermined rotation number, and the high rotation region may be defined as a region having the predetermined rotation number or more. However, the “predetermined number of rotations” here may be changed according to the engine load, for example. For example, at the time of steady operation, the operations of the first turbocharger and the second turbocharger may be controlled in accordance with the operation region set in the map indicated by the engine load and the engine speed.

  The “shift-up process” may be defined as starting when the accelerator is fully closed or the clutch is released, whichever comes first. Further, the shift-up process may be defined as being completed at the timing when the shift stage is changed by the shift lever operation.

  According to the above configuration, the diesel engine includes the first turbocharger including the first turbine and the first compressor, and the second turbocharger including the second turbine and the second compressor having relatively large inertia. Is a so-called two-stage turbocharged diesel engine. By operating at least the first turbocharger in the low speed region where the engine speed is relatively low, and operating the second turbocharger in the high speed region where the engine speed is relatively high, It is possible to obtain a desired supercharging pressure in a wide operating range from a low speed to a high speed. In the low rotation region, both the first turbocharger and the second turbocharger are operated, and the region in which both the first and second turbochargers are operated is the low rotation region. It can be a part. On the other hand, in the high speed region, it is preferable to stop the operation of the first turbocharger from the viewpoint of reducing the resistance.

  When the operation state of the diesel engine is in the high speed range and the manual transmission shift-up process is performed, the operation is stopped during the period until the accelerator pedal is depressed after the start of the shift-up process. In addition, the first turbocharger is operated even in the high rotation region. In the manual transmission shift-up process, the accelerator is fully closed (and the clutch is released), so the engine load is reduced or the engine is not loaded (hereinafter referred to as “no load” including these). Since the exhaust flow rate is reduced, the operation of the second turbocharger is substantially stopped, but the first turbocharger is operated when the engine is not loaded. Since the first turbine of the first turbocharger is relatively small and has a small inertia, it can operate even when the exhaust gas flow rate is low. The operation of the first turbocharger maintains the supercharging pressure or suppresses the decrease in supercharging pressure.

  As a result, when the accelerator pedal is depressed after the completion of the upshifting process, the supercharging pressure is maintained at a relatively high state, so that the acceleration feel at the time of reacceleration is improved. This is particularly effective when the operating state of the engine remains in the high rotation region even after a gear shift, and if normal, the first turbocharger does not operate during reacceleration.

  An exhaust bypass passage that bypasses the first turbine is connected to the exhaust passage, and a regulation valve whose opening degree is adjusted by the controller is disposed in the exhaust bypass passage, When the operating state of the diesel engine is in the high rotation range, the regulator valve may be opened, and the regulator valve may be closed during the upshift control.

  When the operating state of the diesel engine is in the high rotation range, the exhaust valve flows by bypassing the first turbine, and the operation of the first turbocharger stops.

  On the other hand, the regulator valve is closed during upshift control. As a result, the exhaust gas flows to the first turbine side, and the first turbocharger operates. As described above, this improves the acceleration feel at the time of reacceleration after the end of the upshift process.

  Here, during the shift-up process, as described above, the accelerator is fully closed (and the clutch is released) and the engine is unloaded, so the exhaust flow rate is low, and the first turbocharger can be operated. Does not over-rotate or is unlikely. Note that “closing the regulating valve” includes setting the opening to such an extent that leakage occurs, in addition to fully closing the regulating valve. That is, “closing the regulating valve” includes operating the first turbocharger while preventing the over-rotation by substantially closing the regulating valve.

  The intake passage of the diesel engine is connected to an intake bypass passage that bypasses the first compressor and whose opening and closing is controlled by the controller, and the controller is configured to control the intake bypass passage during the upshift control. May be closed.

  Since the intake air passes through the first compressor by closing the intake bypass passage, the boost pressure is maintained or the boost pressure is reduced during the upshift control in which the first turbocharger is operating. Is suppressed.

  The controller may delay the stop timing of the first turbocharger that was activated during the upshift control after the shift stage change in the manual transmission is completed.

  In this way, after the shift stage change in the manual transmission is completed, in other words, after the shift-up process is completed and the accelerator pedal is started, the operation of the first turbocharger is also performed. Will be continued. Since the inertia of the first turbine of the first turbocharger is relatively small, the number of revolutions of the first turbocharger increases early, and the supercharging pressure rises quickly. The acceleration feeling is further improved by a combination of the acceleration response and the relatively high supercharging pressure maintained when the accelerator pedal is depressed as described above. In addition, as the boost pressure rises quickly, the fuel injection amount that was in the fuel cut state during the shift-up process can be increased quickly, so that the engine speed can be increased quickly. To rise. This also contributes to improving the acceleration feel. Such control is particularly effective when the engine operating state remains in the high speed range even after shifting, and normally only the second turbocharger must be operated to perform re-acceleration. It is.

  The first turbocharger may be stopped when the operation of the second turbocharger is substantially started. For example, the operation of the first turbocharger is performed at the timing when a predetermined time has elapsed since the accelerator pedal was started to be depressed and when the accelerator pedal was depressed more than a predetermined amount, whichever comes first Can be stopped.

  The controller controls the operation of the first and second turbochargers so that a target supercharging pressure corresponding to an operating state of the engine is obtained in a normal time other than the shift-up control. The pressure feedback control may be executed.

  During normal times, supercharging pressure feedback control is performed to control the operation of the first and second turbochargers so as to achieve a target supercharging pressure according to the engine operating state, particularly the engine load. In this boost pressure feedback control, the target boost pressure becomes zero in the shift-up process including the accelerator fully closed (and the clutch released) because the engine becomes no load. As a result, the supercharging pressure is reduced.

  On the other hand, as described above, during the upshift process in the high rotation region, the boost pressure is maintained during the upshift process by interrupting the boost pressure feedback control and executing the upshift control. Alternatively, a decrease in the supercharging pressure is suppressed, and a relatively high supercharging pressure can be secured at the time of reacceleration.

  Here, the supercharging pressure feedback control is restored after the completion of the upshifting process, but a gradual change control may be interposed between the upshifting control and the supercharging pressure feedback control. In addition, during the upshift process in which the boost pressure feedback control is interrupted, the target boost pressure is not reduced to zero due to the engine becoming unloaded, for example, immediately before the start of the upshift process. You may make it hold | maintain a target supercharging pressure. In other words, if the target boost pressure is set to zero during the upshift process, the change in the target boost pressure becomes too large before the start of the upshift process, during the process, and after the end of the process. Thus, when the boost pressure feedback control is restored after the completion of the upshift process, the feedback control may become unstable. Therefore, during the shift-up process, by maintaining the target boost pressure immediately before the start of the process, there is almost no change in the target boost pressure, and the boost pressure feedback control after return is stabilized.

  As described above, according to the control device for a diesel engine with a turbocharger, when the operation state of the diesel engine is in a high rotation range, when the shift-up process of the manual transmission is performed, the shift-up is performed. By operating the first turbocharger that has stopped operating during the period from the start of the process until the accelerator pedal is depressed, the boost pressure is maintained or the decrease in the boost pressure is suppressed. Is done. As a result, a relatively high supercharging pressure is maintained at the time of re-acceleration after the end of the upshifting process, so that the acceleration feel is good.

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 a figure which shows an example of the operation | movement map of a 2 stage turbocharger. It is a main flowchart which concerns on control of the supercharger before and after a shift-up process. 5 is a flowchart according to a shift-up determination step process in the main flow shown in FIG. (A) Accelerator opening signal, (b) Accelerator opening change rate, (c) Engine speed, (d) Fuel injection amount, (e) Clutch operation signal related to supercharger control before and after the shift-up process , (F) gear position signal, (g) neutral signal, (h) shift determination step signal, (i) target boost pressure and actual boost pressure, (j) regulate valve opening, (k) waste gate valve It is a timing chart of an opening, (l) intake bypass valve opening, and (m) acceleration G.

  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 vehicle on which the engine 1 is mounted is an MT vehicle having a manual transmission 73, and the output torque accompanying the driving of the engine 1 is a manual transmission that is connected to the crankshaft 15 via the clutch mechanism 72. 73 to the drive wheel 74.

  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 When a lost motion mechanism that selectively transmits the operating state of one of the first and second cams to the exhaust valve is included, and the operating state of the first cam is transmitted to the exhaust valve 22 The exhaust valve 22 operates in a normal mode in which the valve 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. In addition, the valve operates in a special mode in which the exhaust is opened twice so that the valve is opened during the intake stroke.

  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 execution of the internal EGR is not limited to the double opening of the exhaust. For example, the internal EGR control may be performed by opening the intake valve 21 twice, or by opening the intake twice. An internal EGR control may be performed in which the burned gas remains by providing a negative overlap period in which both the intake valve 21 and the exhaust valve 22 are closed in the intake stroke. 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. Injected and 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.

  On the downstream side of the exhaust manifold in the exhaust passage 40, the turbine 62b of the small turbocharger 62, the turbine 61b of the large turbocharger 61, and exhaust for purifying harmful components in the exhaust gas in order from the upstream side. A 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.

  A portion of the intake passage 30 between the surge tank 33 and the throttle valve 36 (that is, a portion on the downstream side of the small compressor 62a of the small turbocharger 62), the exhaust manifold and the small turbocharger in the exhaust passage 40. The portion between the turbocharger 62 and the small turbine 62 b (that is, the upstream portion of the small turbocharger 62 from the small turbine 62 b) is an exhaust gas recirculation for recirculating a part of the exhaust gas to the intake passage 30. They are connected by a passage 50. The exhaust gas recirculation passage 50 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. It includes a passage 51 and a cooler bypass passage 53 for bypassing the EGR cooler 52. The cooler bypass passage 53 is provided with a cooler bypass valve 53 a for adjusting the flow rate of the exhaust gas flowing through the cooler bypass passage 53.

  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.

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. SW5, O ₂ sensor SW6 for detecting an oxygen concentration in the exhaust gas and, the detection signal of the vehicle speed sensor SW7 for detecting a vehicle speed is input, the engine 1 and the vehicle by performing various calculations based on these detection signals The state is determined, and according to this, the injector 18, the glow plug 19, the valve-operated VVM 71, various valves 36, 51a, 5 A control signal is output to the actuator 3a.

  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 regulator valve 64a, and the wastegate valve 65a to the openings set according to the operating state of the engine 1, respectively. Specifically, as shown in an example of the operation map in FIG. 3, when the engine 1 is warm, the PCM 10 does not fully open the small intake bypass valve 63a and the regulating valve 64a in the first region (A) on the low rotation side. When the waste gate valve 65a is fully closed, only the small turbocharger 62 or both the large and small turbochargers 61 and 62 are operated. On the other hand, in the second region (B) on the high rotation side, the small turbocharger 62 is over-rotated and exhaust resistance, so the small intake bypass valve 63a and the regulating valve 64a are fully opened, and the wastegate By opening the valve 65a close to a fully closed 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 15 or less (for example, 14), thereby improving exhaust emission performance and thermal efficiency. It is trying to improve.

(Outline of engine 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 exhaust gas recirculation into the cylinder 11a is controlled by controlling the opening degree of the throttle valve 36, the exhaust gas recirculation valve 51a, and the cooler bypass valve 53a (that is, external EGR control) or by controlling the VVM 71 (that is, internal EGR control). Control the rate.

  Furthermore, 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 61a 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.

(Supercharger control during the shift-up process)
As described above, during the steady state, each of the small turbocharger 62 and the large turbocharger 61 is feedback-controlled according to the operating state of the engine 1 (see FIG. 3). Here, when the upshifting operation of the manual transmission 73 is performed in the second region (B) in which the large turbocharger 61 is activated and the small turbocharger 62 is deactivated, the accelerator is fully closed and When the clutch mechanism 72 is released, the engine 1 enters a no-load state and temporarily enters a fuel cut state. As a result, the target boost pressure of the boost pressure feedback control is set to zero, so that the PCM 10 fully opens the regulating valve 64a, the wastegate valve 65a, and the small intake bypass valve 63a in response to this. To. Further, the exhaust flow rate is also reduced when the engine 1 is in a no-load state. As a result, the supercharging pressure decreases during the upshift process. For this reason, even if the accelerator pedal is depressed and re-acceleration is attempted after the upshifting process is completed, the acceleration must be started from a state where the supercharging pressure is low. .

  Further, immediately after the shift-up process is completed, when the operating state of the engine 1 remains in the second region (B) where only the large turbocharger 61 operates, for example, from the third speed to the fourth speed. At the time of the upshift, the load and the rotational speed of the engine 1 are reduced through the upshift from the operating state shown in FIG. 3 (1), so that the first region (A) and the second region (B) There is a case where the engine 1 shifts to the driving state indicated by (2) in the vicinity of the boundary, and then the load and the rotational speed of the engine 1 increase due to depression of the accelerator pedal (see arrows in FIG. 3). In this case, at the time of re-acceleration, only the large turbocharger 61 having relatively large inertia is operated, while the load and the rotational speed of the engine 1 are relatively low in the second region (B). Since the exhaust flow rate is low in this state, the rotation speed of the large turbocharger 61 does not increase easily, and the increase in the supercharging pressure is greatly delayed. As a result, the acceleration feel is further deteriorated.

  Therefore, in this engine system, in order to improve the acceleration feel at the time of re-acceleration after the upshift process, the PCM 10 interrupts the boost pressure feedback control during the upshift process and stops its operation. The upshift control for operating the small turbocharger 62 is executed.

  FIG. 4 shows a main flow related to the control of the supercharging pressure during the upshift process, which is executed by the PCM 10. In step S41 after the start, various signals necessary for the subsequent control are read. In step S42, a processing operation for upshift determination is performed based on the read signals. In step S43, it is determined whether or not the shift-up determination is within a permitted range. That is, in step S43, when the engine speed is within a predetermined upper and lower limit speed, the vehicle speed is equal to or higher than the predetermined speed, the gear position is equal to or lower than the predetermined gear stage, and the brake signal is OFF, the upshift determination When it is determined that it is within the permitted range, and any one of the conditions is not satisfied, it is determined that it is not within the permitted range. When it is not within the permitted range (NO), the process proceeds to step S46, where it is determined that there is an error, and the upshift determination is terminated. On the other hand, when it is in the permitted range for the upshift determination in step S43 (when YES), the process proceeds to step S44 after setting the upshift determination permission flag. In step S44, the flow of the upshift determination step process shown in FIG. 5 is executed. This shift-up determination step processing is performed by sequentially determining the execution of the accelerator fully closed, the clutch mechanism 72 opened, the shift operation, the clutch mechanism 72 engaged, and the accelerator pedal depression included in the shift up process. This is a logic for determining whether or not the upshifting process is being executed, and this process makes it possible to start the aforementioned upshifting control early when the upshifting process starts. In addition, when it is determined that the process is not the upshift process, the upshift control can be immediately stopped. Here, the shift-up determination step process will be described with reference to the flow of FIG. 5 and the timing chart of FIG. The timing chart of FIG. 6 is an example of a timing chart of each parameter during the upshift process from the 3rd speed to the 4th speed as shown in FIG. This corresponds to the case of shifting to the operation state (2). Note that the gear position signal in FIG. 5F is a gear position estimated based on the rotational speed of the engine 1 and the vehicle speed, and is not used for the upshift determination step process.

  First, in step S51, it is determined whether or not it is shift-up determination step 1. The shift-up determination step 1 is detection of a change in the accelerator opening (see FIG. 6B) or detection of release of the clutch mechanism 72 (see FIG. 6E). That is, when the occupant returns the accelerator pedal and the amount of deviation of the accelerator opening exceeds a predetermined amount and the accelerator opening is equal to or less than the predetermined opening, or when the clutch mechanism 72 is released by depressing the clutch pedal, If Step 1 of the upshift process is determined (see FIG. 6H), the process proceeds to Step S52. On the other hand, when those signals are not detected for a predetermined time or more, the process proceeds to step S516, that is, a normal supercharging pressure feedback control described later as a timeout.

  In step S52, it is determined whether there is a shift determination error. This determination is to determine whether or not an operation different from the shift-up process is being performed. For example, when the clutch mechanism 72 is continuously released for a predetermined time or more, an error determination is made that it is not a shift-up process (for example, the vehicle is decelerating), and the process proceeds to step S516. On the other hand, when it is not an error determination (NO), the process proceeds to step S53.

  In step S53, the regulating valve 64a, the waste gate valve 65a, and the small intake bypass valve 63a are each set to a predetermined opening.

  Specifically, as indicated by a solid line in FIG. 6 (j), the regulator valve 64a that has been set to fully open to stop the operation of the small turbocharger 64 because it is in the second region (B). To close. In the illustrated example, the regulating valve 64a is not set to be fully closed, but is set to an opening degree at which leakage occurs. This is to prevent over-rotation of the small turbocharger 64. If the small turbocharger 64 does not over-rotate, the regulating valve 64a may be fully closed. Similarly, as indicated by a solid line in FIG. 6 (l), the small intake bypass valve 63a that is set to be fully opened to stop the operation of the small turbocharger 64 is located in the second region (B). Fully closed.

  Further, as shown by a solid line in FIG. 6 (k), the waste gate valve 65a is not fully opened but is kept fully closed.

  Further, as described above, after the upshift process is started, the supercharging pressure feedback control is interrupted, but the target supercharging pressure is not set to zero as shown by the solid line in FIG. The target boost pressure just before the start of the upshift process is maintained as it is. As shown by the dotted line in FIG. 6 (i), if the target boost pressure is set to zero, the target boost pressure changes greatly at the start of the shift-up process and at the end of the shift-up process. Therefore, after the upshift process is completed and the control returns to the supercharging pressure feedback control, the feedback control may be adversely affected. On the other hand, by maintaining the target boost pressure immediately before the start of the upshifting process as it is, a large change in the target boost pressure is eliminated, so that the boost pressure feedback control after the end of the upshifting process is stabilized. .

  In a succeeding step S54, it is determined whether or not it is a shift-up determination step 2. The shift-up determination step 2 is to detect the release of the clutch mechanism 72 when a change in the accelerator opening is detected in the shift-up determination step 1 described above, and to detect the release of the clutch mechanism 72 in the shift-up determination step 1. When this is done, a change in the accelerator opening is detected. That is, in the two steps of the shift-up determination step 1 and the shift-up determination step 2, the two operations of fully closing the accelerator and opening the clutch mechanism 72 are detected regardless of the order. If YES in step S54, it is determined that step 2 of the upshift process is determined (see FIG. 6H), and the process proceeds to step S55. On the other hand, after the accelerator is fully closed or the clutch mechanism 72 is released, if the next operation is not performed and a time-out occurs, the process proceeds from step S54 to step S516, assuming that it is not a shift-up process. Here, the timeout related to the shift-up determination step 1 and step 2 is set to be relatively short. This is because the operation of fully closing the accelerator and releasing the clutch mechanism 72 is not limited to the upshifting operation but is also performed when the vehicle is decelerating. In order to return to normal feedback control early, the timeout is set to a relatively short time.

  In step S55, it is determined whether there is a shift determination error. When it is not an error (NO), the process proceeds to step S56, and the opening degrees of the regulating valve 64a, the waste gate valve 65a and the small intake bypass valve 63a are set to predetermined opening degrees. For example, it holds at the opening set in step S53 (see the solid lines of (k), (k), and (l) in FIG. 6). On the other hand, if an error determination is made in step S55, the process proceeds to step S516. An example of the error determination at this step can be a case where the fuel injection amount becomes a predetermined amount or more.

  Here, as indicated by broken lines in FIGS. 6 (j), 6 (k), and 6 (l), the regulating valve 64a, the wastegate valve 65a, and the small intake bypass valve 63a are each set to a predetermined opening degree. The actual opening is changed. That is, the regulating valve 64a is changed from open to closed, the waste gate valve 65a is kept closed, and the small intake bypass valve 63a is changed from open to closed. Among these, the actuator that operates the regulating valve 64a is configured to adjust the opening degree of the regulating valve 64a by the supplied negative pressure, and the capacity thereof is set to be relatively large. For this reason, as shown in the figure, the response of the opening degree change of the regulating valve 64a may be delayed.

  Returning to the flowchart of FIG. 5, in step S <b> 57, it is determined whether it is shift-up determination step 3. The shift-up determination step 3 is that the gear position of the manual transmission 73 is neutral (see (g) in FIG. 6). In other words, in the shift-up operation of the manual transmission 73, when shifting from the shift stage before the shift-up (third speed in the example) to the shift stage after the shift-up (fourth speed in the example), This is to be neutral. When a neutral signal is detected, it is determined that step 3 of the upshift process is determined (see FIG. 6H), and the process proceeds to step S58. On the other hand, when a timeout occurs without detecting a neutral signal, the process proceeds to step S516.

  In step S58, it is determined whether there is a shift determination error. For example, when the manual transmission 73 is neutral and a predetermined time has elapsed, an error determination is made that it is preferable to return to normal feedback control rather than to continue boost pressure shift-up control. The process proceeds to step S516. On the other hand, when NO is determined in step S58, the process proceeds to step S59, and the regulating valve 64a, the waste gate valve 65a, and the small intake bypass valve 63a are set to predetermined opening degrees. For example, the opening set in step S53 is maintained.

  In step S510, it is determined whether it is shift-up determination step 4. The upshift determination step 4 is that the manual transmission 73 is detected to be other than neutral (see (g) of FIG. 6). That is, when the upshifting operation of the manual transmission 73 is completed via neutral, the process proceeds to step S511. On the other hand, when a timeout occurs without detecting a neutral OFF signal for a predetermined time or longer, the process proceeds from step S510 to step S516.

  In step S511, it is determined whether there is a shift determination error. For example, when the shift-up operation of the manual transmission 73 is completed but the release of the clutch mechanism 72 continues for a predetermined time or more, an error determination is made, and the process proceeds from step S511 to step S516. Here, the predetermined time (timeout time) related to the shift-up determination step 4 and the determination step 5 described later is set longer than the timeout time related to the shift-up determination step 4 and step 5 described above. This is because there is almost no doubt that the operation is a shift-up process when the manual transmission 73 once becomes neutral and shifts to another shift stage as in the shift-up determination step 4. This is because there is a low demand for returning to the normal feedback control by stopping the supply pressure shift-up control. When the determination in step S511 is NO, the process proceeds to step S512, and the regulating valve 64a, the wastegate valve 65a, and the small intake bypass valve 63a are each set to a predetermined opening, for example, the opening set in step S53. To do.

  In step S513, it is determined whether it is shift-up determination step 5. In the upshift determination step 5, it is determined that the upshift operation has been completed and the occupant has depressed the accelerator pedal. If YES is determined, the process proceeds to step S514. On the other hand, for example, when a time-out occurs without depressing the accelerator pedal, the process proceeds from step S513 to step S516. In step S514, it is determined whether there is a shift determination error. If YES, the process proceeds to step S516, and if NO, the process proceeds to step S515.

  In step S515, since the upshift process has been completed, the gradual change control for smoothly connecting the upshift control to the supercharging pressure feedback control is performed. In other words, this gradual change control is to continue the boost pressure shift-up control even after the shift-up process is completed and the accelerator pedal is depressed. In the gradual change control, as the accelerator pedal is depressed (see FIG. 6 (a)), the fuel injection is started and the exhaust gas flow rate is increased as shown in FIG. 6 (d). The regulation valve 64a is gradually opened mainly for the purpose of preventing rotation and avoiding an increase in the back pressure of the engine 1. On the other hand, the opening degree of the waste gate valve 65a and the small intake bypass valve 63a is maintained at a predetermined opening degree, for example, the opening degree set in step S53.

  When the upshift determination step 5 continues for a predetermined time set in advance, or when the fuel injection amount exceeds the injection amount set in advance, the routine proceeds to step S516 and normal boost pressure feedback is performed. Return to control. That is, since the operating state of the engine 1 is in the second region (B) and only the large turbocharger 61 is operated, the regulator valve 64a is fully opened (the solid and broken lines in FIG. 6 (j)). The small intake bypass valve 63a is fully opened (see the solid line and the broken line in FIG. 6 (l)). The wastegate valve 65a remains fully closed (see the solid line and the broken line in FIG. 6 (k)). Then, the process returns to step 45 in the flow of FIG. 4 to complete the upshift determination.

  Thus, as shown in FIGS. 6 (a), 6 (b), and 6 (e), when the accelerator is fully closed and the clutch mechanism 72 is opened, the engine 1 is in a no-load state, and as shown in FIG. The number gradually decreases, and the fuel injection amount is set to substantially zero as shown in FIG. As a result, in the supercharging pressure feedback control, the target supercharging pressure is also set to zero (see the alternate long and short dash line in FIG. 5 (i)). Accordingly, the target opening degree of the regulating valve 64a is set to be fully open (refer to the one-dot chain line in the figure (j)), and the target opening degree of the waste gate valve 65a is set to the full opening (the one-dot chain line in the figure (k)). The target opening of the small intake bypass valve 63a is set to fully open (see the alternate long and short dash line in FIG. 1). As a result, the target boost pressure is set to zero and the exhaust flow rate decreases as the engine 1 becomes unloaded. Therefore, as shown by the dotted line in FIG. In the middle, the actual supercharging pressure is greatly reduced. This means that when the accelerator pedal is depressed and re-acceleration is attempted after completion of the upshifting process, acceleration must be started from a state where the supercharging pressure is low. In addition, the operation of both the small turbocharger 62 and the large turbocharger 61 is substantially stopped, and when the operating state of the engine 1 is in the second region (B) during re-acceleration. Only the large turbocharger 61 operates. As a result, as shown by the dotted line in FIG. 8 (i), the boost pressure is delayed at the time of reacceleration, and as shown by the alternate long and short dash line in FIG. Will get worse.

  On the other hand, in the above-described shift up control, when the shift up process is started, the small turbocharger 62 is operated by closing the regulating valve 64a and closing the small intake bypass valve 63a. Since the small turbine 62b of the small turbocharger 62 has small inertia, it rotates even when there is no load on the engine 1 where the exhaust flow rate decreases, and the small compressor 62a is thereby driven. As shown, a decrease in supercharging pressure is suppressed. As a result, when reacceleration is attempted after completion of the upshifting process, acceleration can be started from a relatively high supercharging pressure.

  Further, by continuing the operation of the small turbocharger 62 even after the accelerator pedal is depressed, the supercharging pressure rises early, which is advantageous for the acceleration G. In particular, when the boost pressure is low at the start of reacceleration and the intake air amount is small, the fuel injection amount cannot be increased (see the one-dot chain line in FIG. 4D). As shown by the solid line in FIG. (D), the fuel injection amount can be increased. This is also advantageous for increasing the supercharging pressure, and the rotational speed and acceleration G of the engine 1 are increased early. As a result, the acceleration feel is very good.

  Further, by fully closing the wastegate valve 65a during the shift-up process, the rotation speed of the large turbine 65b is suppressed from decreasing. As a result, after completion of the upshift process, when the normal intake pressure feedback control is resumed through the gradual change control, the large turbocharger 65 operates quickly, so that a desired supercharging pressure can be reliably obtained. It becomes like this. This is also advantageous for improving the acceleration feel.

  Furthermore, by performing the determination of the upshift process by a plurality of steps corresponding to a plurality of operations included in the upshift process, an existing sensor can be used without using only a sensor for detecting the upshift. Can be used to detect the shift-up process at an early stage, and the boost pressure shift-up control can be started promptly. This is advantageous in improving the acceleration feel at the time of re-acceleration after the above-described shift-up process. On the other hand, the determination of the shift-up process by multiple steps can also be detected at an early stage that it is not a shift-up process. It becomes possible to return to feedback control early.

1 Diesel engine 10 PCM (controller)
30 Intake passage 40 Exhaust passage 61 Large turbocharger (second turbocharger)
61a Large compressor (second compressor)
61b Large turbine (second turbine)
62 Small turbocharger (1st turbocharger)
62a Small compressor (first compressor)
62b Small turbine (first turbine)
63 Small intake bypass passage (intake bypass passage)
63a Small intake bypass valve 64 Small exhaust bypass passage (exhaust bypass passage)
64a Regulating valve 72 Clutch mechanism 73 Manual transmission

Claims (5)

A diesel engine,
A first turbocharger having a first turbine disposed in an exhaust passage of the diesel engine and a first compressor disposed in an intake passage of the diesel engine;
A second turbocharger having a second turbine disposed in the exhaust passage and having a larger inertia than the first turbine, and a second compressor disposed in an intake passage of the diesel engine;
When the operation state of the diesel engine is in a low rotation region, at least the first turbocharger is operated, and the operation region of the diesel engine is in a high rotation region having a higher rotation speed than the low rotation region. A controller configured to activate the second turbocharger at a time; and
When the engine operating state is in the high speed range and the shift-up process of the manual transmission including the full closure of the accelerator is performed, after the start of the shift-up process, the controller A control device for a diesel engine with a supercharger that performs upshift control for operating the first turbocharger during a period until it is depressed. In the control apparatus of the diesel engine with a supercharger according to claim 1,
An exhaust bypass passage that bypasses the first turbine is connected to the exhaust passage,
A regulating valve whose opening degree is adjusted by the controller is disposed in the exhaust bypass passage,
The controller is a control device for a turbocharged diesel engine that opens the regulator valve when the operation state of the diesel engine is in the high rotation range and closes the regulator valve during the shift-up control. In the control apparatus of the diesel engine with a supercharger according to claim 1 or 2,
The intake passage of the diesel engine is connected to an intake bypass passage that bypasses the first compressor and whose opening and closing is controlled by the controller.
The controller is a control device for a turbocharged diesel engine that closes the intake bypass passage during the upshift control. In the control apparatus of the diesel engine with a supercharger of any one of Claims 1-3,
The controller is a control device for a diesel engine with a supercharger that delays the stop timing of the first turbocharger that was activated during the upshift control after the shift stage change in the manual transmission is completed. In the control apparatus of the diesel engine with a supercharger of any one of Claims 1-4,
The controller controls the operation of the first and second turbochargers so that a target supercharging pressure corresponding to an operating state of the engine is obtained in a normal time other than the shift-up control. A control device for a turbocharged diesel engine that performs pressure feedback control.

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