JP2016125365A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a chance of replenishing an accumulator, which supplies compressed air to an intake passage, with a necessary amount of the compressed air in an internal combustion engine mounted on a vehicle.SOLUTION: An internal combustion engine comprises: an exhaust turbocharger which sends intake air flowing in an intake passage into a cylinder after compressing the same with a compressor driven by rotation of a turbine using energy of exhaust flowing in the exhaust passage; an accumulator which is connected to the intake passage and can store compressed air discharged from a vacuum pump, supplying negative pressure to a brake booster reinforcing braking force of a braking device to apply a brake to a vehicle, when the same generates the negative pressure; an opening and closing valve which can open and close communication of the intake passage with the accumulator; and a control device which performs control to increase an amount of the intake air to be filled in the cylinder in a manner that supplies the compressed air stored in the accumulator to the intake passage by opening the opening and closing valve when an engine is rotated at a low rotation rate not more than a predetermined rate and high torque demand is increased with an accelerator opening not less than a predetermined opening.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an internal combustion engine with an exhaust turbocharger.

  As an internal combustion engine for vehicles, a turbo engine provided with an exhaust turbocharger is known. The exhaust turbocharger is configured such that a drive turbine disposed on the exhaust passage side of the internal combustion engine and a compressor disposed on the intake passage side are coaxially connected and interlocked. The remaining energy of the exhaust is used to rotate the turbine, and thus the compressor impeller (compressor wheel), and pump the compressor so that the intake air is compressed (supercharged) and sent to the cylinder. Can do.

  When the driver depresses the accelerator pedal greatly in order to start or accelerate the stopped vehicle, it is necessary to quickly increase the engine torque in response to the acceleration request to promote acceleration. However, even if the opening of the throttle valve is increased from the idling operation or the operation region of low rotation and low load close thereto, the charging efficiency of the intake air does not increase immediately due to the presence of the turbo lag.

  In particular, recent turbo engines are designed to lower the compression ratio while lowering the displacement and increasing the boost pressure in order to achieve both improved fuel efficiency and suppression of knocking or pre-ignition. For this reason, sufficient engine torque is not always output until the supercharging by the exhaust turbocharger begins to take effect in the low rotation range, and there is a concern that the driver may be dissatisfied with the acceleration response.

  Therefore, the compressed air is stored in the accumulator tank in advance, and the compressed air stored in the accumulator tank at the time of the turbo lag from when the throttle valve is opened until the supercharging by the exhaust turbocharger is started is taken into the intake passage. (For example, refer to the following patent document). As a result, even before the exhaust turbocharger starts to work, the amount of intake air charged in the cylinders can be increased to increase the engine torque, and an improvement in acceleration response can be expected.

Japanese Patent Laid-Open No. 08-260991 JP 2009-281292 A

  In the internal combustion engine disclosed in the above-mentioned patent document, an accumulator tank is connected downstream of the compressor of the exhaust turbocharger in the intake passage, and a part of the intake air that is compressed by the compressor and flows toward the cylinder is supplied to the accumulator tank. I try to introduce it.

  In order to store compressed air in the pressure accumulating tank, the amount of intake air charged in the cylinder must be reduced. Therefore, the accumulator tank can be replenished with compressed air only in a relatively high speed and high load operating region where the cylinder can be filled with a necessary and sufficient amount of intake air even if the accumulator tank is supplied with compressed air. Become. In other words, the opportunity to store compressed air in the pressure accumulating tank is limited by the driver's intention to drive, the situation surrounding the vehicle, and the like. For example, when traveling in an urban area where roads are congested, there is a possibility that compressed air cannot be sufficiently accumulated in the pressure accumulating tank. Therefore, it may fall into a situation where compressed air in the pressure accumulator tank is scarce when it is important.

  An object of the present invention is to increase the opportunity to replenish compressed air necessary for an accumulator tank that supplies compressed air to an intake passage.

  The present invention is an internal combustion engine mounted on a vehicle, which uses the energy of exhaust gas flowing through an exhaust passage to rotate a turbine and drive a compressor to compress and feed intake air flowing through the intake passage into a cylinder. Compressed air discharged when a vacuum pump that generates negative pressure is connected to an exhaust turbocharger and a vacuum pump that supplies negative pressure to a brake booster that enhances the braking force of a brake device that brakes the vehicle. A pressure accumulating tank that can store, an on-off valve that can block communication between the intake passage and the pressure accumulating tank, and the opening and closing of the engine when the engine speed is low and the accelerator opening is high or low. A control device that opens the valve and supplies compressed air stored in the accumulator tank to the intake passage to increase the amount of intake air charged in the cylinder. To constitute a combustion engine.

  ADVANTAGE OF THE INVENTION According to this invention, the opportunity to replenish compressed air required for the pressure accumulation tank which supplies compressed air to an intake passage can be increased.

The figure which shows the structure of the internal combustion engine for vehicles of one Embodiment of this invention. The figure which shows the relationship between the driving | operation area | region of the internal combustion engine of the embodiment, and supercharging by an exhaust turbo supercharger.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment. The internal combustion engine of the present embodiment is a compression ignition type four-stroke engine such as a diesel engine or a HCCI (homogeneous-charge compression ignition) engine, and a plurality of cylinders 1 (one of which is shown in FIG. 1). Are shown). An injector 11 that directly injects fuel into the combustion chamber of the cylinder 1 is installed on the ceiling of the combustion chamber of each cylinder 1. Further, a glow plug (residual heat plug) 12 and a swirl control valve 13 are provided in the vicinity of the intake port of each cylinder 1.

  The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, a compressor 51 of the exhaust turbocharger 5, a compressor 61 of the exhaust turbocharger 6, a water-cooled intercooler 35, an electronic throttle valve 32, a surge tank 33 and an intake manifold 34 are disposed upstream. Are arranged in this order.

  The exhaust passage 4 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42, an exhaust turbine 62 of the exhaust turbocharger 6, an exhaust turbine 52 of the exhaust turbocharger 5, and an exhaust purification device 41 are disposed on the exhaust passage 4. The exhaust emission control device 41 includes a filter that removes particulate matter contained in the exhaust (Particulate Material) and a catalyst that promotes oxidation or reduction of harmful substances.

  The exhaust turbochargers 5 and 6 are configured such that the exhaust turbines 52 and 62 and the impellers of the compressors 51 and 61 are coaxially connected via a shaft and interlocked with each other. Then, the impellers of the turbines 52 and 62 and the compressors 51 and 61 are rotationally driven using the energy of the exhaust, and the compressor is pumped with the rotational force to compress and compress (supercharge) the intake air. Into cylinder 1.

  The internal combustion engine of the present embodiment is a so-called two-stage turbo (sequential turbo) engine including two exhaust turbochargers 5 and 6. The exhaust turbocharger 5 is a high-speed turbocharger that works in an operation region where the engine speed is relatively high. On the other hand, the exhaust turbocharger 6 is a low-speed turbocharger that works in an operation region where the engine speed is relatively low. The capacity of the low-speed turbocharger 6 is smaller than the capacity of the high-speed turbocharger 5.

  In the intake passage 3, an intake bypass passage 36 that bypasses the compressor 61 of the low-speed turbocharger 6 is provided, and a valve 37 that opens and closes the outlet of the intake bypass passage 36 is provided. The valve 37 controls the flow rate of intake air flowing through the intake bypass passage 36. There is no intake bypass passage that bypasses the compressor 51 of the high-speed turbocharger 5.

  Further, the exhaust passage 4 also includes an exhaust bypass passage 43 that bypasses the turbine 62 of the low-speed turbocharger 6, and an exhaust bypass passage 44 that bypasses the turbine 52 of the high-speed turbocharger 5, and Exhaust bypass valves 45 and 46 for opening and closing the respective inlets of the exhaust bypass passages 43 and 44 are provided. The valve 45 controls the flow rate of exhaust flowing through the exhaust bypass passage 43, and the valve 46 controls the flow rate of exhaust flowing through the exhaust bypass passage 44. The exhaust bypass valves 45 and 46 may be referred to as WGV (Waste Gate Valve).

  Valves 37 and 46 are VSV (Vaccum Switching Valve) using negative pressure actuators 371 and 461. The negative pressure actuators 371 and 461 are diaphragm actuators, and negative pressure and an elastic biasing force by a built-in spring are applied to one surface of the diaphragm, and atmospheric pressure is applied to the other surface. The negative pressure is supplied from the vacuum pump 91. The vacuum pump 91 generates a negative pressure having a certain magnitude. Electromagnetic solenoid valves 372 and 462 are installed on pipes connecting the diaphragm actuators 371 and 461 and the vacuum pump 91, respectively. The magnitude of the negative pressure that actually acts on one surface of the diaphragms of the diaphragm actuators 371 and 461 varies depending on the opening degree of the electromagnetic solenoid valves 372 and 462. The opening degrees of the valves 37 and 46 change according to the difference between the differential pressure between the negative pressure and the atmospheric pressure acting on both surfaces of the diaphragm and the elastic biasing force of the spring that elastically biases the diaphragm. That is, the opening degree of the valves 37 and 46 can be operated through the operation of the opening degree of the electromagnetic solenoid valves 372 and 462.

  On the other hand, the valve 45 is an EVRV (Electric Vacuum Regulating Valve) which is an electromagnetic valve.

  External EGR (Exhaust Gas Recirculation) devices 2 and 7 return a part of the exhaust gas flowing through the exhaust passage 4 to the intake passage 3 to be mixed with the intake air. The internal combustion engine of this embodiment includes two EGR devices 2 and 7. The EGR device 2 realizes a so-called low pressure loop EGR, and communicates the downstream side of the exhaust purification device 41 in the exhaust passage 4 to the upstream side of the compressor 51 of the high-speed turbocharger 5 in the intake passage 3. 21 and an EGR valve 22 that opens and closes the EGR passage 21 are included as elements. The EGR valve 22 controls the flow rate of the low-pressure loop EGR gas that flows through the EGR passage 21.

  The EGR device 7 realizes a so-called high-pressure loop EGR, and an EGR passage 71 that communicates the upstream side of the turbine 62 of the low-speed turbocharger 6 in the exhaust passage 4 to the downstream side of the intercooler 35 in the intake passage 3. An EGR valve 72 that opens and closes the EGR passage 71 is included as an element. The EGR valve 72 controls the flow rate of the high-pressure loop EGR gas that flows through the EGR passage 71.

  In addition, an exhaust throttle valve 47 is installed in the exhaust passage 4 at a location downstream of the connection location of the low-pressure loop EGR passage 21. The pressure on the upstream side of the compressor 51 in the intake passage to which the low-pressure loop EGR passage 21 is connected varies depending on the degree of supercharging by the compressor 51. As a result, the flow rate of EGR gas flowing through the low pressure loop EGR passage 21 changes. The exhaust throttle valve 47, together with the EGR valve 22, functions to converge the flow rate of the low-pressure loop EGR gas, and thus the EGR rate, which is the ratio of EGR gas in the intake air charged in the cylinder 1, to the target value.

  The vehicle of this embodiment is accompanied by a vacuum booster (vacuum) brake booster 8. The brake booster 8 has a constant pressure chamber for storing negative pressure and a transformation chamber to which atmospheric pressure is applied, and uses the differential pressure between the negative pressure and the atmospheric pressure to boost the pedaling force of the brake pedal. It is what has been. When the brake pedal is not operated by the driver, the constant pressure chamber of the brake booster 8 communicates with the variable pressure chamber, and the variable pressure chamber is isolated from the atmospheric pressure. When the brake pedal is operated, the constant pressure chamber and the variable pressure chamber are interrupted, and the atmosphere is introduced into the variable pressure chamber. As a result, the pressure difference between the constant pressure chamber and the variable pressure chamber becomes a control pressure that boosts the depression force of the brake pedal. The brake pedal force amplified by the brake booster 8 is converted into hydraulic pressure in the master cylinder 81. The hydraulic fluid pressure output from the master cylinder 81 is transmitted to a brake device (not shown) such as a brake caliper or a wheel cylinder via a hydraulic circuit (not shown), and is used for braking the vehicle by the brake device.

  In the present embodiment, a vacuum pump 92 is employed as means for supplying a negative pressure necessary for the operation of the brake booster 8. The vacuum pump 92 is assumed to be an electric type driven by an electric motor, but is driven by transmission of rotational torque from a crankshaft that is an output shaft of an internal combustion engine or a camshaft that drives an intake / exhaust valve. A mechanical type may be used. The constant pressure chamber of the brake booster 8 is connected to a suction port of a vacuum pump 92 that outputs a negative pressure. Valves (check valves, switching valves) for keeping negative pressure in the constant pressure chamber and preventing positive pressure from being applied to the constant pressure chamber on the pipe line connecting the constant pressure chamber of the brake booster 8 and the suction port of the vacuum pump 92 Etc.) 82 is provided. Note that the vacuum pump 92 may be the same (common) as the vacuum pump 91 that supplies negative pressure for opening the VSVs 37 and 46.

  Further, the intake passage 3 of the internal combustion engine of the present embodiment is provided with a pressure accumulation tank 38 capable of supplying compressed air to the intake passage 3 when the exhaust turbochargers 5 and 6 do not work. The accumulator tank 38 stores compressed air that is discharged when the vacuum pump 92 generates a negative pressure. For this purpose, the pressure accumulation tank 38 is connected to a discharge port of a vacuum pump 92 that outputs a positive pressure. In particular, the electric vacuum pump 92 is activated when the driver depresses the brake pedal, which is an opportunity to accumulate compressed air in the pressure accumulation tank 38. A valve (check valve, switching valve, etc.) 39 for retaining compressed air in the pressure accumulation tank 38 is provided on a pipe line connecting the pressure accumulation tank 38 and the discharge port of the vacuum pump 92. The accumulator tank 38 is connected to the downstream side of the compressor 61 (and further the intercooler 35) of the low-speed turbocharger 6 in the intake passage 3. Here, the pressure accumulation tank 38 may be connected to the upstream side of the throttle valve 32, or may be connected to the downstream side of the throttle valve 32. An open / close valve 30 for opening and closing the pipe line is provided on the pipe line connecting the accumulator tank 38 and the intake passage 3.

  An ECU (Electronic Control Unit) 0 serving as a control device for an internal combustion engine according to the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface of the ECU 0 includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal b output from an engine rotation sensor that detects the rotation angle of the crankshaft and the engine speed, and an accelerator pedal. The accelerator opening signal c output from a sensor that detects the amount of depression of the engine or the opening of the throttle valve 32 as an accelerator opening (in other words, a required engine torque or load), and in the surge tank 33 of the intake passage 3 (that is, The intake air temperature / intake pressure signal d output from the intake air temperature / intake pressure sensor for detecting the temperature and pressure (supercharging pressure) of the intake air (flowing into the cylinder 1), and output from the atmospheric pressure sensor for detecting the atmospheric pressure. At the atmospheric pressure signal e, the most upstream of the intake passage 3, that is, downstream of the air cleaner 31 and upstream of the connection point of the low pressure loop EGR passage 21. An air flow meter for detecting the flow rate and temperature of fresh air, a fresh air flow rate / temperature signal f output from a fresh air temperature sensor, an intake pressure downstream of the compressor 51 and upstream of the compressor 61 in the intake passage 3 (high-speed turbocharger) The intake pressure signal g output from the intake pressure sensor that detects the supercharging pressure by the machine 5), the brake signal h output from the sensor that detects that the brake pedal has been depressed or the amount of depression of the brake pedal, etc. are input. The

  From the output interface of the ECU 0, the fuel injection signal i for the injector 11, the opening operation signal j for the throttle valve 32, the opening operation signal k for the EGR valve 22, and the opening operation signal for the EGR valve 72. Opening operation signal m for the electromagnetic solenoid valve 372 that controls the opening / closing drive of the signal l, VSV 37, opening operation signal n for the EVRV 45, and opening operation signal o for the electromagnetic solenoid valve 462 that controls the opening / closing drive of the VSV 46. Then, an opening operation signal p is output to the exhaust throttle valve 47, an opening operation signal q is output to the opening / closing valve 30, an operation control signal r is output to the vacuum pump 92, and the like.

  The processor of the ECU 0 interprets and executes a program stored in the memory in advance, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 0 acquires various information a, b, c, d, e, f, g, and h necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and is filled in the cylinder 1. Estimate the fuel injection amount commensurate with the amount of intake air (fresh air). At the same time, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, required EGR rate (or EGR amount), and target supercharging of supercharging by the exhaust turbochargers 5 and 6 Various operating parameters such as pressure are determined. The ECU 0 applies various control signals i, j, k, l, m, n, o, p, q, r corresponding to the operation parameters via the output interface.

  FIG. 2 shows the relationship between the operating range of the internal combustion engine of the present embodiment and the supercharging by the exhaust turbochargers 5 and 6. In FIG. 2, the horizontal axis represents the engine speed and the vertical axis represents the engine torque. In a region A1 where the accelerator opening is small and the engine torque output from the internal combustion engine is relatively small, the flow rate of the exhaust gas flowing through the exhaust passage 4 is small, and the exhaust turbochargers 5 and 6 do little or no work. Accordingly, the ECU 0 opens the VSVs 37 and 46 and the EVRV 45, respectively, and opens the bypass passages 36, 43 and 44 to reduce the pumping loss of the internal combustion engine as much as possible. At this time, the opening degree of the VSV 46 may be feedback-controlled so that the intake pressure downstream of the compressor 51 and upstream of the compressor 61, which is known with reference to the intake pressure signal g, becomes the target intake pressure. The target intake pressure is preferably set to an atmospheric pressure obtained by referring to the atmospheric pressure signal e or a value in the vicinity thereof. Then, the loss due to the compressor 51 of the high-speed turbocharger 5 in the intake passage 3 is reduced, which can contribute to improvement in fuel efficiency.

  In the region A2 where the accelerator opening is larger than a certain level and the engine torque is larger than a certain level, but the engine speed is relatively low, supercharging by the low speed turbocharger 6 is performed. In the region A2, the ECU 0 fully closes the VSV 37 and closes the intake bypass passage 36, and causes all the intake air flowing through the intake passage 3 to flow into the compressor 61. At the same time, the EVRV 45 is fully closed or its opening degree is reduced, and the exhaust gas flowing through the exhaust passage 4 is sufficiently introduced into the turbine 62. At this time, the opening degree of the EVRV 45 may be feedback-controlled so that the intake pressure obtained by referring to the intake air temperature / intake pressure signal d follows the target boost pressure. In addition, the ECU 0 feedback-controls the opening degree of the VSV 46 so that the intake pressure upstream of the compressor 51 and downstream of the compressor 61, which is known with reference to the intake pressure signal g, becomes the target intake pressure. The target intake pressure is preferably set to an atmospheric pressure obtained by referring to the atmospheric pressure signal e or a value in the vicinity thereof. Then, the inlet side of the compressor 61 of the low-speed turbocharger 6 does not become negative pressure, the supercharging of the intake air charged in the cylinder 1 becomes efficient, and the compressor 51 of the high-speed turbocharger 5 Loss is reduced, which can contribute to improved fuel efficiency.

  In the region A4 where the accelerator opening is larger than a certain level, the engine torque is larger than a certain level, and the engine speed is relatively high, supercharging is performed by the high-speed turbocharger 5. In the area A4, the ECU 0 opens the VSV 37 and the EVRV 45 to open the bypass passages 36 and 43. Then, the VSV 46 is fully closed or its opening degree is reduced, and the exhaust gas flowing through the exhaust passage 4 is sufficiently introduced into the turbine 52. At this time, the intake pressure obtained by referring to the intake air temperature / intake pressure signal d and / or the intake pressure upstream of the compressor 51 and downstream of the compressor 61 obtained by referring to the intake pressure signal g are determined. The opening degree of the VSV 46 is feedback-controlled so as to follow the target boost pressure.

  In the region A4, supercharging by the low-speed turbocharger 6 is not performed, but the rotation of the compressor 61 and the turbine 62 needs to be maintained at a rotation speed that does not cause excessive rotation (for example, about 100,000 rpm). is there. This is based on the assumption that the bearing seal of the low-speed turbocharger 6 rotates the shaft, and if the rotation of the compressor 61 and the turbine 62 ceases or stops, lubricating oil leakage occurs (the intake bypass passage 36 is opened). And when the inlet side of the compressor 51 is in a negative pressure state, the lubricating oil is sucked). Therefore, the ECU 0 keeps the opening degree of the VSV 37 as large as possible, while maintaining the opening degree of the EVRV 45 so that the rotation speeds of the compressor 61 and the turbine 62 are maintained within the predetermined rotation speed range or in the vicinity thereof. Slightly squeeze.

  A region A3 where the accelerator opening is larger than a certain level, the engine torque is larger than a certain level, and the engine speed is medium is a transient region between the low-speed turbo region A2 and the high-speed turbo region A4. In the transition region A3, supercharging is performed by both the low-speed turbocharger 6 and the high-speed turbocharger 5. In the process of transition from the low-speed turbo region A2 to the high-speed turbo region A4, as the engine speed increases, the respective openings of the VSV 37 and the EVRV 45 gradually increase so as to go from substantially fully closed to substantially fully open. At this time, the ECU 0 feedback-controls the opening degree of the EVRV 45 so that the intake pressure obtained by referring to the intake air temperature / intake pressure signal d follows the target boost pressure. In turn, the opening of the VSV 46 gradually decreases as the engine speed increases. The ECU 0 feedback-controls the opening degree of the VSV 46 so that the intake pressure upstream of the compressor 51 and downstream of the compressor 61, which is known with reference to the intake pressure signal g, follows the target boost pressure.

  By the way, when the driver depresses the accelerator pedal to start or accelerate the stopped vehicle, it is necessary to increase the engine torque promptly in response to the acceleration request. However, even if the opening degree of the throttle valve 32 is increased from an idling operation or an operation region of low rotation and low load close thereto, the charging efficiency of the intake air does not increase immediately due to the presence of the turbo lag. Referring to FIG. 2, the transition from the point X to the point Y must be promptly realized. The turbocharger for low speed is used until the flow rate of the exhaust gas flowing through the exhaust passage 4 increases. 6 does not work sufficiently, and the transition from the X point to the Y point may inevitably be delayed.

  Therefore, the ECU 0 of the present embodiment opens the on-off valve 30 and sucks in the compressed air stored in the pressure accumulating tank 38 when the engine speed is low at a predetermined value or lower and the accelerator opening is a high required torque at a predetermined value or higher. Supply to the passage 3. As a result, the amount of intake air charged into the cylinder 1 is increased, and the intake air charging efficiency is increased during the turbo lag period until the supercharging by the low-speed turbocharger 6 starts to take effect.

  Supply of compressed air from the accumulator tank 38 to the intake passage 3 is performed for a predetermined time (for example, one time) corresponding to a period from when the accelerator pedal is depressed by the driver until supercharging by the low-speed turbocharger 6 starts to take effect. Only about a second). In other periods, the open / close valve 30 is closed. When the internal combustion engine is a small displacement engine, the capacity of the pressure accumulating tank 38 may be small. For example, it is sufficient to store compressed air of about 3 to 4 atm in a 5 liter tank. 2 to 5 g of compressed air is sufficient. This amount of compressed air is about 100 liters when expanded.

  In the present embodiment, the internal combustion engine is mounted on a vehicle, and the intake air flowing through the intake passage 3 by rotating the turbines 52 and 62 and driving the compressors 51 and 61 using the energy of the exhaust gas flowing through the exhaust passage 4. Is connected to the exhaust turbochargers 5 and 6 that pressurize and compress the gas to the cylinder 1 and the intake passage 3 to supply a negative pressure to the brake booster 8 that enhances the braking force of the brake device that brakes the vehicle. A pressure accumulation tank 38 capable of storing compressed air discharged when the vacuum pump 92 generates negative pressure, an open / close valve 30 capable of blocking communication between the intake passage 3 and the pressure accumulation tank 38, and an engine speed The compressed air stored in the pressure accumulating tank 38 by opening the on-off valve 30 when the engine is rotating at a low speed less than a predetermined value and the accelerator opening is a high required torque greater than a predetermined value is supplied to the intake passage 3. And configure the internal combustion engine and a control unit 0 to perform a control for increasing the intake air amount to be filled fed to the cylinder 1.

  According to the present embodiment, by using the compressed air stored in the pressure accumulating tank 38 in advance, it is possible to enhance the charging efficiency of the intake air in the operation region of low rotation and high required torque and improve the acceleration response. . In addition, since the compressed air can be accumulated in the pressure accumulating tank 38 by utilizing the opportunity for the vacuum pump 92 associated with the brake booster 8 to operate, the compression in the pressure accumulating tank 38 can be performed when the vehicle restarts or re-accelerates. The risk of falling into a situation where air is scarce is reduced.

  The present invention is not limited to the embodiment described in detail above. For example, the opportunity to store compressed air in the pressure accumulation tank 38 is not limited when the vacuum pump 92 generates negative pressure. In a relatively high rotation and high load operation region, the opening / closing valve 30 is opened, and a part of the supercharged intake air supplied by the exhaust turbochargers 5, 6 is caused to flow from the intake passage 3 into the pressure accumulation tank 38. Thus, it is natural that accumulation of compressed air may be performed.

  The application target of the present invention is not limited to a two-stage turbo engine. That is, the exhaust turbo supercharger provided in the internal combustion engine may be one.

  Other specific configurations of each part can be variously modified without departing from the spirit of the present invention.

  The present invention can be applied to an internal combustion engine mounted on a vehicle.

0 ... Control unit (ECU)
DESCRIPTION OF SYMBOLS 1 ... Cylinder 3 ... Intake passage 38 ... Accumulation tank 30 ... Open / close valve 4 ... Exhaust passage 5, 6 ... Exhaust turbo supercharger 51, 61 ... Compressor 52, 62 ... Turbine 8 ... Brake booster 92 ... Vacuum pump

Claims (1)

An internal combustion engine mounted on a vehicle,
An exhaust turbocharger that uses the energy of exhaust gas flowing through the exhaust passage to rotate the turbine and drive the compressor to pressurize and compress the intake air flowing through the intake passage and send it to the cylinder;
A pressure accumulating tank that is connected to the intake passage and can store compressed air discharged when a vacuum pump that generates a negative pressure is supplied to a brake booster that enhances a braking force of a brake device that brakes the vehicle; ,
An open / close valve capable of blocking communication between the intake passage and the pressure storage tank;
The amount of intake air that is filled into the cylinder by supplying the compressed air stored in the accumulator tank to the intake passage by opening the on-off valve when the engine speed is low at a predetermined speed and the accelerator opening is high at a predetermined required torque. An internal combustion engine comprising a control device that performs control to increase the amount.

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