JP4968592B2 - Internal combustion engine control device - Google Patents

Description

  The present invention relates to a control device in an internal combustion engine provided with air supply means for supplying additional air to an intake passage.

  Various internal combustion engines have been proposed in which additional air from another system is supplied to the intake passage. For example, the device disclosed in Patent Document 1 has a pressure accumulating tank connected to an intake passage, holds air pressurized by a turbocharger and made high pressure in the pressure accumulating tank, and has an acceleration request In addition, by releasing the air in the pressure accumulating tank downstream of the throttle valve in the intake passage, the charging efficiency is increased and the acceleration of the internal combustion engine is assisted.

  On the other hand, the device disclosed in Patent Document 2 includes a throttle valve and a compressor arranged downstream thereof, and an assist air passage that bypasses the throttle valve and the compressor upstream and downstream, and a pressure downstream of the compressor. When the air pressure is positive, the assist air passage is blocked by a solenoid valve to prevent backflow of air.

Japanese Utility Model Publication No. 61-69438 Japanese Utility Model Publication No. 6-87668

  However, in these devices of Patent Documents 1 and 2, since additional air is supplied downstream of the throttle valve in the intake passage, when the pressure downstream of the throttle valve is increased, sufficient deceleration can be performed at the time of request for deceleration. May not be obtained.

  Accordingly, an object of the present invention is to provide a novel means for obtaining sufficient deceleration when a deceleration is requested in a system including an air supply means for supplying air to an intake passage.

  An internal combustion engine control apparatus according to the present invention is an internal combustion engine control apparatus comprising an intake air amount control valve disposed in an intake passage and air supply means for supplying air to the intake passage downstream of the intake air amount control valve. Determining means for determining whether a downstream pressure, which is a pressure in the intake passage downstream of the intake amount control valve, is larger than an upstream pressure, which is a pressure in the intake passage upstream of the intake amount control valve, and a deceleration request And a downstream pressure reducing means for reducing the downstream pressure by controlling the intake air amount control valve to the open side when the downstream pressure is larger than the upstream pressure. It is characterized by.

  In the present invention, the downstream pressure, which is the pressure in the intake passage downstream of the intake air amount control valve, is increased by the air supply from the air supply means. And when there exists a deceleration request | requirement and the said downstream pressure is larger than an upstream pressure, a downstream pressure reduction means controls an intake air amount control valve to a releasing side, and reduces the said downstream pressure. Therefore, in the present invention, sufficient deceleration can be obtained when a deceleration request is made.

  The apparatus of the present invention suppresses the flow of air between the intake air amount control valve downstream and the intake air amount control valve upstream by the intake air amount control valve when there is an acceleration request and the downstream pressure is larger than the upstream pressure. You may further provide the backflow suppression means to make it. In this case, the backflow of air at the time of acceleration request can be suppressed and the responsiveness can be improved.

  The air supply means is particularly preferably a pressure accumulating tank that stores air in the intake passage.

  Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, an engine according to an embodiment of the present invention is a gasoline internal combustion engine, and a turbocharger 3 is installed to supercharge high pressure air into a combustion chamber 2 formed in a cylinder 1. The turbocharger 3 includes a turbine wheel 4, a compressor wheel 5, and a shaft 6 that connects the central portions of these wheels 4 and 5. The turbine wheel 4 and the compressor wheel 5 are provided in an exhaust passage 7 and an intake passage 8 that communicate with the combustion chamber 2, respectively, and rotate around the axis of the shaft 6. The turbine wheel 4 is rotationally driven by the exhaust gas passing through the exhaust passage 7 and the compressor wheel 5 is rotated. As a result, the air sucked into the intake passage 8 from the atmosphere port 9 is increased in pressure and supplied to the combustion chamber 2 side. Sent.

  A pressure accumulating tank 11 is connected to the intake passage 8 downstream of the compressor wheel 5 via a passage 10. The accumulator tank 11 can hold high-pressure air as will be described later. The control valve 12 is provided at a bent portion of the passage 10 to open and close the passage 10, thereby communicating or blocking the pressure accumulation tank 11 and the intake passage 8. The control valve 12 is a poppet type and is driven by a diaphragm device 13.

  The diaphragm device 13 is configured such that the inside of the shell 14 is partitioned into a spring chamber 16 and a variable pressure chamber 17 by a diaphragm 15, and a spring 18 that is always engaged with the diaphragm 15 is accommodated in the spring chamber 16. The spring chamber 16 opens to the atmosphere via the passage 19 and the orifice 22. On the other hand, the rod 23 fixed to the diaphragm 15 protrudes from the variable pressure chamber 17 to the outside of the shell 14 and is connected to the control valve 12. Therefore, when the pressure difference between the variable pressure chamber 17 and the spring chamber 16 becomes larger than the elastic force of the spring 18, the control valve 12 is displaced by the deformation of the diaphragm 15 and opens the passage 10. In the present embodiment, when the pressure difference is 350 mmHg or more, the control valve 12 opens the passage 10.

  The accumulator tank 11 discharges the held high-pressure air from the second passage 24 into the intake passage 8 during acceleration operation of the engine. The second passage 20 is connected to the intake passage 8 on the downstream side of the throttle valve 26 via the discharge valve 27, and supplies additional air to the downstream side of the throttle valve 26. The discharge valve 27 is a poppet type and is opened and closed by a solenoid 25.

  The waste gate valve 40 limits the number of revolutions of the turbocharger 3 to suppress the supercharging pressure to a constant value, and opens and closes a bypass passage 41 that connects the upstream side and the downstream value of the turbine wheel 4 in the exhaust passage 7. To do.

  The diaphragm device 42 that opens and closes the waste gate valve 40 has the same configuration as the diaphragm device 13, and includes a shell 43, a diaphragm 46 that divides the shell 43 into a variable pressure chamber 44 and a spring chamber 45, and a spring chamber 45. And a spring 47 provided on the head. The variable pressure chamber 44 is always in communication with the intake passage 8 via the passage 48, while the spring chamber 45 is always guided to the atmosphere. A rod 49 fixed to the diaphragm 46 projects from the spring chamber 45 to the outside of the shell 43 and is connected to a link 50 provided on a tube wall forming the bypass passage 41. This link 50 is coupled to the waste gate valve 40. Therefore, the waste gate valve 40 bypasses the bypass passage 41 when the pressure difference between the variable pressure chamber 44 and the spring chamber 45, that is, the difference between the pressure in the intake passage 8 and the atmospheric pressure (supercharging pressure) overcomes the elastic force of the spring 47. In this embodiment, it is opened at 380 mmHg or more. Therefore, when the supercharging pressure reaches 380 mmHg, a part of the exhaust gas is released to the atmosphere via the bypass passage 41, whereby the rotation of the turbine wheel 4 is suppressed and the supercharging pressure does not increase any more. A fuel injection valve 51 is provided downstream of the throttle valve 26 in the intake passage 8.

  The throttle valve 26 and the discharge valve 27 are controlled by an electronic control unit (ECU) 100 comprising a microcomputer. The ECU 100 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output port (I / O port). The ROM stores programs in accordance with the flowchart shown in FIG. 2 in addition to various processing programs, and the CPU controls the throttle valve 26 and the release valve 27 as described later by a drive circuit (not shown) according to these programs. Control. In addition to the control processing of the throttle valve 26 and the release valve 27 according to the present invention, the ROM of the ECU 100 calculates the target fuel injection amount based on the intake air amount, the engine speed, and the like, and calculates the calculated target fuel. A processing program for performing fuel injection control for injecting an injection amount of fuel by a fuel injection valve is stored.

  The ECU 100 outputs a command signal to the drive circuit based on the engine speed, turbine speed, accelerator pedal opening, internal pressure of the accumulator tank 11, upstream pressure and downstream pressure in the intake passage, and controls the throttle valve 26 and the release valve. 27 is controlled. For this purpose, various detectors are provided. That is, a turbine rotation sensor 110 that detects the rotation speed of the shaft 6 is provided in the vicinity of the shaft 6 of the turbocharger 3, and a tank pressure sensor 111 that detects the internal pressure of the pressure accumulation tank 11 is connected. The upstream pressure sensor 112 is provided in the intake passage, upstream of the throttle valve 26 and downstream of the intercooler 52, and detects upstream pressure (ie, compressor pressure). The downstream pressure sensor 113 is provided in the intake passage and downstream of the throttle valve 26, and detects the downstream pressure (ie, intake manifold pressure). The crank angle sensor 114 is attached to a crankshaft (not shown) and detects the engine speed. If the signals from the turbine rotation sensor 110, pressure sensors 111, 112, 113, and crank angle sensor 114 are analog signals, they are A / D converted and subjected to necessary processing to be sent from the I / O port to the ECU 100. Is input.

  The basic operation of this embodiment is as follows. That is, when the engine is operated at a low load, the waste gate valve 40, the control valve 12, and the release valve 27 are in a closed state. When the engine is under a high load (for example, the supercharging pressure is 350 mmHg or more) and is operated in a steady state, the pressure in the variable pressure chamber 17 of the diaphragm device 13 increases, so the control valve 12 opens the passage 10. The accumulator tank 11 holds a portion of the high-pressure air in the intake passage 8 that is guided.

  When the throttle valve 26 is closed from this state and the engine is decelerated, the negative pressure generated on the downstream side of the throttle valve 26 increases. On the other hand, when the engine load decreases, the rotational speed of the turbocharger 3 decreases, and the intake air pressure in the intake passage 8 decreases. Therefore, the pressure in the variable pressure chamber 17 of the diaphragm device 13 decreases, and the control valve 12 has a spring 18. And the passage 10 is closed. As a result, the pressure accumulation chamber 11 is maintained in a high pressure state.

  On the other hand, the ECU 100 controls the throttle valve 26 and the release valve 27 according to the processing routine of FIG. 2 to supply additional air from the pressure accumulation tank 11 to the intake passage 8 downstream of the throttle valve 26.

  In FIG. 2, the ECU 100 first determines whether the accelerator pedal opening, that is, the depression amount is larger than a predetermined reference value based on the detection value of the accelerator pedal sensor 24 (S10). When negative, that is, when the opening degree of the accelerator pedal is small, the ECU 100 fully closes the release valve 27 (S60), and then the intake manifold pressure detected by the downstream pressure sensor 113 is detected by the upstream pressure sensor 112. It is determined whether the pressure is greater than the compressor pressure (S70). When the intake manifold pressure is equal to or lower than the compressor pressure, as a result of a negative determination, the ECU 100 controls the throttle valve 26 to a normal opening corresponding to the accelerator pedal opening (S50).

  In this case, since no additional air is supplied from the pressure accumulating tank 11, the upstream pressure, that is, the compressor pressure detected by the upstream pressure sensor 112, as shown at times t0 to t1 in FIG. Gradually decreases as a result of opening. Further, the downstream pressure, that is, the intake manifold pressure detected by the downstream pressure sensor 113 gradually increases as a result of the supply of air through the throttle valve 26 and the supercharging from the turbine wheel 5.

  If the determination in step S10 is affirmative, that is, if the accelerator pedal opening is larger than the reference value, the ECU 100 controls the release valve 27 to be fully open (S20, t1). As a result, additional air is supplied to the intake passage downstream of the throttle valve 26 through the release valve 27. Next, the ECU 100 determines whether the intake manifold pressure detected by the downstream pressure sensor 113 is larger than the compressor pressure detected by the upstream pressure sensor 112 (S30), and whether the intake manifold pressure is equal to the compressor pressure or the compressor pressure. If lower, the ECU 100 controls the throttle valve 26 to a normal opening degree corresponding to the accelerator pedal opening degree as a result of the negative determination (S50, times t1 to t2 in FIG. 3).

  When the intake manifold pressure is higher than the compressor pressure in step S30, as a result of affirmative determination, the ECU 100 controls the throttle valve 26 to be fully closed (S40, t2). As a result, additional air is supplied through the discharge valve 27 in a state where the flow of air through the throttle valve 26 is blocked (time t2 to t5 in FIG. 3). Note that the time (t0 to t2) from the start of depression of the accelerator pedal to the fully closing of the throttle valve 26 is usually about 0.2 seconds. If the accelerator pedal opening does not change as it is, this state continues until time t5 when the compressor pressure increases and becomes equal to or higher than the intake manifold pressure, and the intake manifold pressure increases rapidly during that time.

  As described above, when the air supply from the pressure accumulating tank 11 increases the downstream pressure, which is the pressure in the intake passage downstream of the throttle valve 26, and there is an acceleration request and the downstream pressure is larger than the upstream pressure, the ECU 100 However, the throttle valve 26 suppresses the air flow between the throttle valve 26 downstream and the throttle valve 26 upstream. Accordingly, in the present embodiment, sufficient acceleration can be obtained by suppressing the backflow of air through the throttle valve 26. The intake manifold pressure before the improvement according to the present embodiment (that is, when the throttle valve 26 is not closed) is prevented from rising due to the backflow of air through the throttle valve 26, and is broken at time t2 to t5. It changes as shown by a. That is, in this embodiment, the acceleration is accelerated by the increase of the intake manifold pressure as compared with the case before the improvement. Further, in the present embodiment, after the suppression, the ECU 100 releases the suppression when the downstream pressure is smaller than the upstream pressure (S30, t5), and thereafter, from both the compressor wheel 5 and the pressure accumulation tank 11 Smooth transition to air supply.

  On the other hand, if the determination in step S70 is affirmative, that is, if the accelerator opening is below a predetermined value (S10) and the intake manifold pressure is higher than the compressor pressure, typically the downstream pressure ( This may occur when a deceleration request is generated due to the accelerator pedal being turned off while the intake manifold pressure is rising (time t3). In this case, the ECU 100 controls the throttle valve 26 to a predetermined opening (S80). The predetermined opening is determined as a fixed value so that the intake manifold pressure can be quickly reduced by the backflow of air through the throttle valve 26. For example, the opening is smaller than fully open and corresponds to idling (idle in FIG. 4). It is preferred that it be larger than (shown as opening). The opening operation of the throttle valve 26 at a predetermined opening is continuously executed until the intake manifold pressure is reduced to be equal to or lower than the compressor pressure (S70, S80, t3 to t4). As a result of the opening operation of the throttle valve 26 with a predetermined opening, the downstream pressure (intake manifold pressure) is reduced, so that sufficient deceleration can be obtained immediately after a request for deceleration due to the accelerator off.

  When the intake manifold pressure becomes equal to or lower than the compressor pressure, the result of the negative determination in step S70 is that the throttle valve 26 is controlled to the normal opening (if the accelerator is in an off state, such as after time t4 in the example of FIG. 4, the throttle valve 26 is an idle opening degree).

  As described above, in this embodiment, the downstream pressure that is the pressure in the intake passage 8 downstream of the throttle valve 26 is increased by the air supply from the pressure accumulation tank 11. When there is a deceleration request and the downstream pressure is greater than the upstream pressure, the ECU 100 controls the throttle valve 26 to the release side to reduce the downstream pressure. Therefore, in this embodiment, sufficient deceleration can be obtained when a deceleration request is made.

  In the present embodiment, since the air supply means is the pressure accumulation tank 11 that accommodates the air in the intake passage 8, the desired effect of the present invention can be obtained with a simple configuration.

  In the above embodiment, the predetermined opening at which the throttle valve 26 is controlled when a deceleration request is made is a fixed value between the fully open and the idle opening. Alternatively, it may be determined dynamically from the driving state of the vehicle, for example, a value proportional to the intake manifold pressure.

  In the above embodiment, when there is an acceleration request and the downstream pressure is higher than the upstream pressure, the throttle valve 26 suppresses the backflow of air (S40). However, the present invention does not perform such control. Also good.

  In the above embodiment, when the downstream pressure is larger than the upstream pressure, the throttle valve 26 is fully closed, thereby blocking the air flow through the throttle valve 26 (S40). If the throttle valve 26 is controlled in the closing direction so as to suppress the backflow of air from the upstream to the upstream, in addition to full opening and full closing, an opening between them is realized in a multi-step or stepless manner. May be. In addition to the fully open and fully closed states of the release valve 27, an intermediate opening degree between the two may be realized in a multistage or stepless manner.

  In the above embodiment, the upstream pressure and the downstream pressure are detected by the dedicated sensors 111 and 112, respectively, but at least one of these values is detected by various sensors such as the turbine rotation sensor 110, the crank angle sensor 114, and the tank internal pressure sensor 111. You may obtain | require by estimation calculation from a detected value, the opening degree of the throttle valve 26, the elapsed time after the opening operation of the discharge valve 27, etc.

  In the above embodiment, the intake air amount control valve is the throttle valve 26, but the intake air amount control valve in the present invention is a bypass valve that opens and closes a bypass passage that bypasses the upstream and downstream sides of the intake passage sandwiching the throttle valve. There may be.

  In the above embodiment, the pressure accumulation tank 11 is employed as the air supply means. However, as the air supply means in the present invention, various configurations other than the pressure accumulation tank can be selected. For example, exhaust gas for supplying exhaust gas to the intake passage It may be a recirculation system (EGR) or a mechanical supercharger (so-called supercharger), and a pulse supercharging valve that performs at least one opening operation and one closing operation in one intake stroke is provided as an intake passage. An inertia supercharging device (pulse supercharging device) that is provided inside and performs supercharging by intake inertia may be used. Further, instead of the turbocharger 3 in the above embodiment, a mechanical supercharger or other supercharging means may be provided upstream of the throttle valve. The present invention can also be applied to engines that use other fuels, such as diesel engines and gaseous fuel engines, and such configurations also belong to the scope of the present invention.

It is a functional block diagram which shows the internal combustion engine control apparatus which concerns on embodiment of this invention. It is a flowchart which shows control of embodiment of this invention. It is a timing diagram which shows the effect | action of embodiment. It is an operation of the embodiment, and is a timing diagram showing a case where there is a deceleration request while the intake manifold pressure is rising.

Explanation of symbols

2 Combustion chamber 3 Turbocharger 7 Exhaust passage 8 Intake passage 11 Accumulation tank 12 Control valve 24 Second passage 26 Throttle valve 27 Release valve

Claims (3)

An internal combustion engine controller comprising: an intake air amount control valve disposed in an intake passage; and air supply means for supplying air to the intake passage downstream of the intake air amount control valve,
Determination means for determining whether a downstream pressure, which is a pressure in the intake passage downstream of the intake amount control valve, is larger than an upstream pressure, which is a pressure in the intake passage upstream of the intake amount control valve;
And further comprising a downstream pressure reducing means for reducing the downstream pressure by controlling the intake air amount control valve to the open side when there is a deceleration request and the downstream pressure is greater than the upstream pressure. An internal combustion engine control device.   When there is an acceleration request and the downstream pressure is larger than the upstream pressure, the intake air amount control valve further includes a backflow suppressing means for suppressing an air flow between the intake air amount control valve downstream and the intake air amount control valve upstream. The internal combustion engine control device according to claim 1, further comprising:   The internal combustion engine control device according to claim 1 or 2, wherein the air supply means is a pressure accumulating tank for storing air in the intake passage.

Images