JP2018031283A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the fixation of a link mechanism for connecting a waste gate valve and an actuator for driving the waste gate valve, in an internal combustion engine having an exhaust turbo supercharger.SOLUTION: In an internal combustion engine for driving a compressor provided on an intake passage by using a turbine provided on an exhaust passage, and having a bypass passage bypassing the turbine and a waste gate valve for opening and closing the bypass passage in the exhaust passage, the waste gate valve is opened by using negative pressure which is generated at a downstream side of a throttle valve in an intake passage at deceleration at which an opening of the throttle valve provided in the intake passage reaches a prescribed opening or smaller.SELECTED DRAWING: Figure 1

Description

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

  The energy of the exhaust gas discharged from the cylinder is used to rotate the exhaust turbine (turbine wheel), the rotation is transmitted to the compressor impeller (compressor wheel), and the intake air is pressurized and compressed (supercharged). An exhaust turbocharger that feeds into a cylinder is well known.

  An internal combustion engine provided with an exhaust turbocharger is usually provided with a waste gate (see, for example, Patent Document 1 below). The waste gate valve opens and closes a bypass connecting the upstream side and the downstream side of the turbine in the exhaust passage, and plays a role of suppressing the pressure of the intake air flowing through the intake passage from becoming excessively large. The waste gate valve is normally opened in a full load or high load operation region where the throttle valve is fully open or close to full open.

  A general waste gate valve is driven by a diaphragm actuator that uses the pressure of supercharged air supplied to the diaphragm chamber. Specifically, the rod connected to the diaphragm is connected to a bracket fixed to the waste gate valve or a support shaft of the waste gate valve, and the displacement of the diaphragm subjected to the supercharging pressure is transmitted to the waste gate valve. Open the waste gate valve.

  If the connecting portion between the rod connected to the diaphragm and the bracket or support shaft of the waste gate valve corrodes and rusts, it becomes difficult to drive the waste gate valve appropriately by the actuator. Then, it becomes impossible to restrict the inflow of exhaust gas to the turbine through the waste gate, and there is a concern that the supercharging pressure becomes excessive and the internal combustion engine is damaged.

  In order to avoid such an event, conventionally, a fail-safe is provided in which the supercharging pressure is always sensed, and when the supercharging pressure exceeds the upper limit value, the fuel supply to the cylinder is temporarily interrupted. (For example, refer to Patent Document 2 below). However, when the fuel-cut is performed with the fail-safe function activated, a so-called “breathing” phenomenon occurs in which the engine torque decreases and the vehicle acceleration decreases, and drivability deteriorates.

Japanese Patent Laying-Open No. 2015-165096 Japanese Patent Laid-Open No. 08-0661104

  An object of the present invention is to prevent sticking of a link mechanism that connects a waste gate valve and an actuator that drives the internal combustion engine accompanied by an exhaust turbocharger.

  In order to solve the above-described problems, the present invention drives a compressor disposed on an intake passage by a turbine disposed on an exhaust passage, and bypasses a bypass passage that bypasses the turbine in the exhaust passage and a waste gate that opens and closes the bypass passage. An internal combustion engine provided with a valve, which opens a waste gate valve using negative pressure generated downstream of the throttle valve in the intake passage when the throttle valve provided in the intake passage is opened to a predetermined value or less. An internal combustion engine to be operated was configured.

  According to the present invention, in an internal combustion engine associated with an exhaust turbocharger, sticking of a link mechanism that connects a waste gate valve and an actuator that drives the waste gate valve can be prevented.

The figure which shows the whole structure of the internal combustion engine for vehicles in one Embodiment of this invention. FIG. 2 is a perspective view showing an exhaust turbocharger and a diaphragm actuator that accompany the internal combustion engine of the embodiment.

  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 spark ignition type four-stroke engine and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives spark voltage generated by the ignition coil and causes spark discharge between the center electrode and the ground electrode. The ignition coil is integrally incorporated in a coil case together with an igniter that is a semiconductor switching element.

  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, an intercooler 35, an electronic throttle valve 32 that is an intake throttle valve, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream side. doing.

  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 52 of the exhaust turbocharger 5, and an exhaust purification three-way catalyst 41 are arranged on the exhaust passage 4. In addition, an exhaust bypass passage 43 that bypasses the turbine 52 and a waste gate valve 44 that is a bypass valve that opens and closes the inlet of the bypass passage 43 are provided.

  The exhaust turbocharger 5 is configured such that an exhaust turbine 52 and an impeller 51 of a compressor are coaxially connected via a shaft 53 and interlocked. Then, the turbine 52 and the impeller 51 are rotationally driven by using the energy of the exhaust gas, and the compressor is pumped with the rotational force, whereby the intake air is pressurized and compressed (supercharged) and sent to the cylinder 1.

  The waste gate valve 44 is opened and closed by a diaphragm actuator 6. The actuator 6 has a diaphragm chamber 61 and a constant pressure chamber 62 separated by a diaphragm 60, and displaces the diaphragm 60 using a differential pressure between the diaphragm chamber 61 and the constant pressure chamber 62. The diaphragm 60 and the waste gate valve 44 are connected via link mechanisms 63 and 442. Specifically, as shown in FIGS. 1 and 2, a valve rod 63 for transmitting the displacement of the diaphragm 60 is connected to the diaphragm 60, and the rod 63 is fixed to the support shaft 441 of the waste gate valve 44. The bracket 442 is connected.

  When the differential pressure between the diaphragm chamber 61 and the constant pressure chamber 62 exceeds a predetermined set pressure, the diaphragm 60 and the valve rod 63 move from the diaphragm chamber 61 side toward the constant pressure chamber 62 side against the elastic biasing force of the spring 64. To displace. As a result, the waste gate valve 44 that has closed the bypass 43 rotates around the support shaft 441 to open the bypass passage 43. On the other hand, when the differential pressure between the diaphragm chamber 61 and the constant pressure chamber 62 is equal to or lower than the set pressure, the diaphragm 60 and the valve rod 63 are returned to their original positions by the elastic biasing force of the spring 64, and the waste gate valve 44 is completely Close to.

  Into the diaphragm chamber 61 of the actuator 6, intake pressure, that is, supercharging pressure, is introduced into a portion of the intake passage 3 downstream of the compressor 51 and upstream of the throttle valve 32. For this purpose, a supercharging pressure introduction flow path 71 for communicating the diaphragm chamber 61 and the relevant part of the intake passage 3, a supercharging pressure introduction flow path 71, a depressurization flow path 72 for opening the diaphragm chamber 61 to the atmosphere, An adjustment valve (vacuum switching valve) 73 for opening and closing the drainage channel 72 is provided.

  The VSV 73 is a known flow rate control valve such as a solenoid valve that receives the control signal l and changes its opening degree. If the opening degree of the VSV 73 is manipulated, a part of the supercharged air flowing from the intake passage 3 into the supercharging pressure introduction passage 71 is released to the atmosphere via the decompression passage 72, and the pressure in the diaphragm chamber 61 is increased. Can be controlled.

  Normally, atmospheric pressure is introduced into the constant pressure chamber 62 of the actuator 6. However, in the internal combustion engine of the present embodiment, the negative pressure of the intake air generated in the downstream portion of the throttle valve 32 in the intake passage 3 can be introduced into the constant pressure chamber 62 of the actuator 6 when necessary. For this purpose, a negative pressure introduction flow path 74 that connects the constant pressure chamber 62 and the corresponding part of the intake passage 3, a VSV 75 that opens and closes the negative pressure introduction path 74, and a pressure release flow path 76 that opens the constant pressure chamber 62 to the atmosphere. A VSV 77 that opens and closes the pressure release passage 76 is provided.

  VSV 75 and VSV 77 are known flow control valves such as solenoid valves that receive control signals m and n and change their opening degrees. By manipulating the opening degree of the VSV 75, intake negative pressure can be introduced into the constant pressure chamber 62 from the downstream side of the throttle valve 32 in the intake passage 3 via the negative pressure introduction passage 74. In addition, if the opening degree of the VSV 77 is manipulated, the intake negative pressure introduced into the constant pressure chamber 62 can be released to the atmosphere via the decompression passage 76. As a result, the magnitude of the pressure in the constant pressure chamber 62 can be controlled.

  An ECU (Electronic Control Unit) 0 that controls the operation of the internal combustion engine of this 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. Or an accelerator opening signal c output from a sensor that detects the opening of the throttle valve 32 as an accelerator opening (in other words, a required load), and a brake pressing amount output from a sensor that detects the amount of depression of the brake pedal. Signal d, intake air temperature / intake pressure signal e output from an intake air temperature / intake pressure sensor for detecting intake air temperature and intake pressure (supercharging pressure) in the intake passage 3 (especially surge tank 33), cooling of the internal combustion engine Cooling water temperature signal f output from a water temperature sensor that detects the water temperature, at multiple cam angles of the intake camshaft or exhaust camshaft A cam angle signal g outputted from the beam angle sensor, battery status signal h or the like to be output from the sensor for detecting an index indicative of the state of charge of the battery (the battery current and / or battery voltage) is input.

  From the output interface of the ECU 0, an ignition signal i for the igniter of the spark plug 12, a fuel injection signal j for the injector 11, an opening operation signal k for the throttle valve 32, and an opening operation signal l for the VSV 73. , The opening operation signal m is output to the VSV 75, and the opening operation signal n is output to the VSV 77.

  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 intake volume. Based on the engine speed, the intake air amount, and the like, various operating parameters such as required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, ignition timing, and the like are determined. . The ECU 0 applies various control signals i, j, k, l, m, and n corresponding to the operation parameters via the output interface.

  The ECU 0 performs a fuel cut that interrupts the fuel supply to the cylinder 1 according to the driving situation. The ECU 0 determines that the fuel cut condition is satisfied, at least when the accelerator pedal depression amount is 0 or less than a threshold value close to 0 and the engine speed is equal to or higher than the fuel cut permission speed. Temporarily interrupt fuel injection. Thereafter, the ECU 0 determines that the fuel cut end condition is satisfied when any of the accelerator pedal depression amount exceeds a threshold value, the engine speed decreases to the fuel cut return speed, etc. Then, the fuel cut is finished, and the fuel injection from the injector 11 is restarted.

  In addition, the ECU 0 performs a fuel cut that interrupts the fuel supply to the cylinder 1 as fail-safe control even when the intake pressure supercharged by the exhaust turbocharger 5 exceeds a required upper limit value. .

  By the way, water flowing into the engine room of the vehicle may be applied to a connecting portion that connects the rod 63 of the actuator 6 and the bracket 442 (or the support shaft 441) of the waste gate valve 44. When the vehicle is operated in a coastal area, salty water is applied to this connection. In addition, when the vehicle is operated in a snowy area, water containing a snow melting agent component is applied to this connecting portion. Although it is a rare case, the connecting portion between the rod 63 and the bracket 442 is rusted due to them, and there is a possibility that the drive of the waste gate valve 44 by the actuator 6 may be hindered.

  In particular, when the driver routinely performs ecological driving without strongly depressing the accelerator pedal, that is, when the internal combustion engine is not frequently operated at full load or high load, the exhaust turbocharger 5 is Since the supercharging pressure does not increase remarkably without doing much work, the opportunity for the actuator 6 to open the waste gate valve 44 is also reduced. Therefore, there is a concern that the connecting portion between the rod 63 and the bracket 442 is rusted and fixed.

  In order to avoid such a problem, in the present embodiment, even in a situation where the pressure of the intake air is low and the waste gate valve 44 originally does not need to be opened, the waste gate valve 44 is intentionally opened by the actuator 6, and the link mechanism 63. 442 is prevented from being rusted.

  The ECU 0 normally closes the VSV 75 to shut off the negative pressure introduction passage 74 and opens the VSV 77 to open the decompression passage 76 to open the constant pressure chamber 62 of the actuator 6 to atmospheric pressure. After that, by operating the opening degree of the VSV 73, the magnitude of the supercharging pressure which is a condition for opening the waste gate valve 44 is controlled. As a result, the supercharging pressure during the full load or high load operation of the internal combustion engine can be suppressed to a required upper limit value or less.

  On the other hand, the ECU 0 opens the VSV 75 while closing the VSV 77 and closing the pressure relief passage 76 at the time of deceleration at which the opening of the throttle valve 32 is fully closed or less than a predetermined opening close to full closing. By opening the negative pressure introduction passage 74, intake negative pressure generated on the downstream side of the throttle valve 32 in the intake passage 3 is introduced into the constant pressure chamber 62 of the actuator 6. Then, even if the pressure of the intake air in the region between the compressor 51 and the throttle valve 32 in the intake passage 3 is not high and the diaphragm chamber 61 is not higher than the atmospheric pressure, the differential pressure between the diaphragm chamber 61 and the constant pressure chamber 62 The waste gate valve 44 can be opened by the actuator 6. Such opening of the waste gate valve 44 is preferably performed while the fuel cut condition is satisfied and the fuel injection from the injector 11 is interrupted.

  As already described, opening the waste gate valve 44 at the time of deceleration when the opening of the throttle valve 32 is fully closed or less than a predetermined opening close to full closing is due to rusting of the connecting portion between the rod 63 and the bracket 442. It is an intention to prevent. Therefore, it is not always necessary to open the waste gate valve 44 when the opening of the throttle valve 32 is fully closed or less than a predetermined opening close to full closing.

  Thus, for example, during one trip (a period from when the ignition switch is turned on and the internal combustion engine is started to when the ignition switch is turned off and the internal combustion engine is stopped), the waste gate valve 44 is given a predetermined number of times (one to several times). After the opening operation is performed a predetermined number of times during the trip, even if the opening degree of the throttle valve 32 is fully closed or less than the predetermined opening degree close to full closing, the waste gate valve 44 is no longer opened. The state where the VSV 75 is closed and the VSV 77 is opened is not performed.

  Alternatively, a certain interval may be provided for the opening operation of the waste gate valve 44. That is, after the opening operation of the waste gate valve 44, the waste gate valve 44 is not closed until the predetermined time elapses even if the opening degree of the throttle valve 32 is fully closed or less than a predetermined opening degree close to full closing. The VSV 75 is closed and the VSV 77 is opened.

  In this embodiment, the turbine 52 disposed on the exhaust passage 4 drives the compressor 51 disposed on the intake passage 3, and the exhaust passage 4 bypasses the turbine 52 and the waste passage 43 opens and closes the bypass passage 43. In the internal combustion engine provided with the gate valve 44, the negative pressure generated on the downstream side of the throttle valve 32 in the intake passage 3 at the time of deceleration when the opening degree of the throttle valve 32 provided in the intake passage 3 becomes a predetermined value or less is used. Thus, an internal combustion engine that opens the waste gate valve 44 is configured.

  According to this embodiment, it is possible to effectively prevent the link mechanisms 63 and 442 connecting the waste gate valve 44 and the actuator 6 from being fixed. Since the actuator 6 can avoid the situation where the waste gate valve 44 cannot be properly opened and closed, and the supercharging pressure can be prevented from increasing beyond the upper limit value, a fail-safe function for correcting excessive supercharging pressure works. The “breathing” phenomenon does not occur, and drivability can be kept high.

  The present invention is not limited to the embodiment described in detail above. Various modifications can be made to the specific configuration of each part, processing procedure, and the like without departing from the spirit of the present invention.

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

0 ... Control unit (ECU)
DESCRIPTION OF SYMBOLS 1 ... Cylinder 11 ... Injector 3 ... Intake passage 32 ... Throttle valve 4 ... Exhaust passage 43 ... Bypass passage 44 ... Wastegate valve 441 ... Support shaft 442 ... Bracket 5 ... Exhaust turbocharger 51 ... Compressor 52 ... Turbine 6 ... Actuator 60 ... Diaphragm 61 ... Diaphragm chamber 62 ... Constant pressure chamber 63 ... Rod

Claims (1)

An internal combustion engine that drives a compressor disposed on an intake passage by a turbine disposed on an exhaust passage, and includes a bypass passage that bypasses the turbine and a wastegate valve that opens and closes the bypass passage in the exhaust passage,
An internal combustion engine that opens a waste gate valve using negative pressure generated downstream of a throttle valve in an intake passage when the throttle valve provided in the intake passage is decelerated to a predetermined value or less.

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