JP2010265902A - Intake device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To securely prevent an excessive negative pressure from acting in a collector while reducing the weight and cost of the collector. <P>SOLUTION: A variable valve mechanism can continuously change an intake air amount of an internal combustion engine by changing the valve lift characteristic of an intake valve 1. A pressure adjustment mechanism is provided for generating predetermined negative pressure inside the collector 38 connected with the intake passages 34 of a plurality of cylinders. When the negative pressure inside the collector is in an excessive negative pressure in which the negative pressure exceeds a predetermined set negative pressure higher than the predetermined negative pressure, fuel injection is stopped. When the negative pressure is between the predetermined negative pressure and the set negative pressure, a fuel injection amount is corrected based on the predetermined negative pressure and the detected negative pressure. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an intake device for an internal combustion engine used in an automobile or the like.

  2. Description of the Related Art In general, an intake device of an internal combustion engine for a vehicle, particularly an internal combustion engine using gasoline as fuel, is provided with a throttle valve upstream of a collector connected to a plurality of cylinders (cylinders). Is adjusted. For this reason, as the throttle valve is closed, the negative pressure in the collector increases (for example, −100 mmHg), and the strength of the collector is set so as to withstand such a large negative pressure.

Japanese Patent Application No. 2001-77467

  By the way, the present applicants have previously applied for an intake device capable of adjusting the intake air amount by a variable valve mechanism that changes the valve lift characteristic of the intake valve as Patent Document 1. In this case, since it is not necessary to use a throttle valve for adjusting the intake air amount, so-called throttle loss can be reduced and eliminated, and the negative pressure acting in the collector can be sufficiently reduced. As a result, for example, the material for forming the collector can be reduced in weight and cost.

  On the other hand, the negative pressure of the intake system is generally also used to perform a recirculation of blow-by gas in the EGR device or a purge operation of the evaporated fuel in the evaporated fuel processing device. The magnitude of the negative pressure required in such a case (for example, −several tens mmHg) is sufficiently smaller than the negative pressure (for example, −several hundred mmHg) generated when adjusting the intake air amount. Therefore, it is preferable to provide a pressure adjusting mechanism for generating a predetermined negative pressure required in the collector in the intake device capable of adjusting the intake air amount by such a variable valve mechanism.

  However, when unexpectedly large negative pressure is applied to the collector due to failure of the pressure adjustment mechanism or deterioration over time, unexpected damage such as damage to the weight-reduced collector or reduction in engine output occurs. There is a fear.

  One object of the present invention is to effectively avoid and suppress damage to a collector, etc., even when an excessive negative pressure acts in the collector in an intake device capable of adjusting the amount of intake air by a variable valve mechanism. It is said.

  In the intake device for an internal combustion engine according to the present invention, a variable valve mechanism capable of continuously changing an intake air amount of the internal combustion engine by changing a valve lift characteristic of the intake valve and an intake passage of a plurality of cylinders are connected. A collector and a pressure adjusting mechanism for generating a predetermined negative pressure inside the collector;

  As described above, since the intake air amount can be continuously adjusted by changing the valve lift characteristic of the intake valve, as described above, the throttle loss due to the conventional throttle valve can be reduced and eliminated, and in addition, it acts on the collector. The negative pressure to be reduced can be made sufficiently small to reduce the weight and cost of the material forming the collector. For example, the collector can be formed of a lightweight and inexpensive resin material.

  Further, since the predetermined negative pressure is generated inside the collector by the pressure adjusting mechanism, the predetermined negative pressure can be applied to a device that uses the negative pressure, for example, an EGR device or an evaporated fuel processing device. The predetermined negative pressure generated by the pressure adjusting mechanism is preferably a minimum negative pressure (for example, −several tens mmHg) required for the EGR device and the evaporated fuel processing device, and is generated when the intake air amount is adjusted. Is set to be sufficiently smaller than the negative pressure (for example, −several hundred mmHg).

  In the first aspect of the present invention, when the negative pressure inside the collector is in an excessively negative state where the negative pressure exceeds at least the predetermined negative pressure (when the predetermined negative pressure larger than the predetermined negative pressure is exceeded), the inside of the collector is opened to the atmosphere. It is characterized by having an atmospheric release mechanism. As a result, for example, even if a failure occurs in the pressure adjustment mechanism, the negative pressure inside the collector does not develop excessively, and this affects other parts of the intake system (for example, the whole collector is deformed by the negative pressure). ) Can be prevented.

  The air release mechanism preferably keeps the inside of the collector open to the atmosphere after its operation, such as a strength weakening section described later. In this case, in addition to simplifying the atmosphere opening mechanism, the inside of the collector after the opening of the atmosphere opening mechanism is maintained at substantially atmospheric pressure, that is, constant pressure, so that the output characteristics of the internal combustion engine are stabilized. On the other hand, in the case of an atmospheric release mechanism that repeatedly opens and closes the atmosphere, the negative pressure inside the collector fluctuates, and the adverse effect of this fluctuation may be reflected in the engine output. On the other hand, in order to provide an atmospheric release mechanism capable of adjusting the pressure in the collector so as not to cause pressure fluctuations, a structure of the same level as the pressure adjusting mechanism is required, and cost increases and complexity of the structure cannot be avoided.

  As an example, the air release mechanism is composed of a strength weakening portion in which a part of the wall portion of the collector is partially weakened.When the negative pressure is excessive, the strength weakening portion is cracked and the inside of the collector is formed. Open to the atmosphere. In this case, the air release mechanism can be provided without increasing the number of parts, and the configuration is simplified. In addition, when the collector is composed of a plurality of parts (divided bodies), it is only necessary to replace the part provided with the strength weakening part when repairing, and the workability is excellent.

  As another example, the atmosphere release mechanism includes a communication hole formed through the wall of the collector, a lid that closes the communication hole, and the lid is locked to the wall of the collector to be held closed. A locking portion, and in the state of excessive negative pressure, the locking of the lid is released and the inside of the collector is opened to the atmosphere. In this case, when the pressure adjusting mechanism is repaired, it is only necessary to return the lid to the original locked state, which is advantageous in that no parts are exchanged as compared with the case where the strength weakening portion described above is used.

  More preferably, the target valve lift characteristic of the intake valve is set based on the operating condition of the internal combustion engine, and the control means for controlling the variable valve mechanism according to the target valve lift characteristic and the operation of the atmosphere release mechanism are performed. Detecting means for detecting, wherein the control means sets different target valve lift characteristics before and after detecting the operation of the atmospheric release mechanism. Therefore, by setting an appropriate target valve lift characteristic corresponding to the pressure in the collector in advance, for example, even in a state where the atmosphere release mechanism is operated and the inside of the collector is maintained at atmospheric pressure, the pressure adjustment mechanism It is possible to ensure an engine output equivalent to that in the normal time when the engine is operating normally and the atmospheric release mechanism is not yet operating.

  Further, when an air cleaner is built in the collector, the atmosphere release mechanism is preferably arranged upstream of the air cleaner in the intake air flow direction. Thereby, when the atmosphere release mechanism is activated, it is possible to prevent dust or the like flowing into the collector through the atmosphere release mechanism from being captured by the air cleaner and entering the cylinder side of the engine.

  According to a second aspect of the present invention, there is provided pressure detecting means for detecting the pressure inside the collector, and fuel injection is stopped when the detected negative pressure inside the collector exceeds a set negative pressure larger than the predetermined negative pressure. When the detected negative pressure inside the collector is between the predetermined negative pressure and the set negative pressure, the fuel injection control means corrects the fuel injection amount based on the predetermined negative pressure and the detected negative pressure It is characterized by providing these.

  In this case, if the negative pressure in the collector exceeds the set negative pressure and becomes excessively large without providing the air release mechanism, the fuel injection is stopped (fuel cut), and the inside of the collector is included due to the excessive negative pressure. It is possible to quickly avoid damage to the intake system. Further, even when the negative pressure inside the collector deviates from a predetermined negative pressure due to a failure of the pressure adjusting mechanism, the fuel injection amount can be corrected as appropriate according to the detected actual negative pressure.

  Typically, the pressure adjusting mechanism makes the negative pressure inside the collector substantially constant (for example, −50 mmHg) in a predetermined operation region (for example, an operation region that requires a predetermined negative pressure in an EGR device or an evaporative fuel processing device). In addition to the adjustment, the pressure inside the collector is almost atmospheric pressure in the region other than the predetermined operation region.

  As described above, according to the first invention having the atmospheric release mechanism, it is possible to reduce the weight and cost of the collector and avoid the application of excessive negative pressure in the collector. Excessive negative pressure can surely eliminate damage to the intake system including the collector.

  Further, according to the second invention having the fuel injection control means, the fuel injection is stopped (fuel) even when an excessive negative pressure acts in the collector while reducing the weight and cost of the collector. Cut), it is possible to quickly avoid the intake system including the inside of the collector from being damaged by such an excessive negative pressure.

The perspective view which shows the operating angle change mechanism which comprises the variable valve mechanism of the intake device of the internal combustion engine which concerns on this invention. FIG. 2 is a cross-sectional view showing a phase changing mechanism that constitutes the variable valve mechanism of FIG. 1. Sectional drawing which shows the collector vicinity of the intake system of the said intake device. FIG. 4 is a cross-sectional view along line AA in FIG. 3. The schematic block diagram which shows the attachment aspect of the collector and attachment bracket of FIG. Explanatory drawing which shows the attachment aspect of the collector upper division body and collector lower division body of the collector of FIG. Action explanatory drawing which shows an example of the pressure adjustment mechanism of the said intake device. Action | operation explanatory drawing which shows the air release mechanism which concerns on 1st Embodiment. Explanatory drawing which shows ECU (engine control unit) as a control part of the said intake device. The flowchart which shows the flow of control which concerns on 1st Embodiment. The characteristic view which shows the operating angle map at the time of normal, and the operating angle map at the time of abnormality. Sectional drawing of the collector vicinity which shows the atmospheric release mechanism which concerns on 2nd Embodiment. FIG. 13 is a cross-sectional view along the line BB in FIG. 12. Sectional drawing of the collector vicinity which concerns on 3rd Embodiment. FIG. 15 is a cross-sectional view along the line CC in FIG. 14. The flowchart which shows the flow of control which concerns on 3rd Embodiment.

  Hereinafter, embodiments in which the present invention is applied to a four-cylinder gasoline internal combustion engine will be described in detail with reference to the drawings. First, a configuration common to all the embodiments will be described with reference to FIGS.

  FIG. 1 shows a variable valve mechanism that can change the valve lift characteristics (valve timing and valve lift amount) of the intake valve 1. This variable valve mechanism includes an operating angle changing mechanism 10 that can change the operating angle and valve lift amount of the intake valve 1, and the phase (for example, the center phase) of the intake valve operating angle with respect to the rotational phase of the crankshaft (not shown). And a phase change mechanism 20 capable of changing the above. Thus, by using the operating angle changing mechanism 10 and the phase changing mechanism 20 together, it is possible to adjust the opening timing and closing timing of the intake valve independently of each other.

  The operating angle changing mechanism 10 includes a drive shaft 11 and a control shaft 12 that extend in parallel to each other in the cylinder row direction. The drive shaft 11 rotates around the shaft by the rotational power transmitted from the crankshaft. A swing cam 13 that is in contact with the valve lifter 2 of the intake valve 1 and pushes down the valve lifter 2 is rotatably fitted on the drive shaft 11, and a cylindrical or columnar drive eccentric cam is provided for each cylinder. (Drive eccentric shaft portion) 14 is fixed or integrally formed. The axis of the outer peripheral surface of the drive eccentric cam 14 is eccentric with respect to the axis of the drive shaft 11, and a ring-shaped first link 15 is rotatably fitted around the outer peripheral surface of the drive eccentric cam 14. . A control eccentric cam (control eccentric shaft portion) 16 having a cylindrical shape or a columnar shape for each cylinder is fixed or integrally formed on the control shaft 12. The axis of the outer peripheral surface of the control eccentric cam 16 is eccentric with respect to the axis of the control shaft 12, and the central portion of the rocker arm 17 is rotatably fitted on the outer peripheral surface of the control eccentric cam 16. . One end of the rocker arm 17 is rotatably connected to the tip of the first link 15, and the other end of the rocker arm 17 is rotatably connected to one end of the rod-shaped second link 18. The other end of the second link 18 is rotatably connected to the tip of the swing cam 13. A potentiometer 203 for detecting the rotational phase of the control shaft 12 is attached to one end side of the control shaft 12. A phase sensor 204 that detects the rotational phase of the drive shaft 11 is provided on one end side of the drive shaft 11.

  The operation of the operating angle changing mechanism 10 will be described. When the drive shaft 11 is rotated around the shaft by the rotational power transmitted from the crankshaft, one end of the first link 15 fitted around the drive eccentric cam 14 is rotationally displaced around the center of the drive shaft 11, and this first link. 15 operates as a whole in a translational direction, and the translational movement of the first link 15 is converted into the rocking movement of the rocker arm 17, so that the rocking cam 13 is within a predetermined rocking range via the second link 18. Swing with. This swinging swing cam 13 abuts against and presses the valve lifter 2 of the intake valve 1, whereby the intake valve 1 is driven to open and close against the reaction force of a valve spring (not shown). Further, when the control shaft 12 is rotationally driven by the actuator 19, the center position of the control eccentric cam 16 serving as the rocking center of the rocker arm 17 is rotationally displaced with respect to the rotation center of the control shaft 12. The postures 15 and 18 change, and the swing characteristic of the swing cam 13 (for example, the center phase of the swing range of the swing cam 13) changes. Thereby, both the operating angle of the intake valve 1 and the valve lift amount continuously change while the central phase of the operating angle of the intake valve 1 remains substantially constant.

  The merit of the operating angle changing mechanism 10 will be described. A swing cam 13 that directly presses the intake valve 1 is provided on the same axis as the drive shaft 11 that rotates about the axis by the rotational power transmitted from the crankshaft. Therefore, substantially the same layout as that of a conventional general direct acting valve system that presses the intake valve by a fixed cam fixed to the camshaft can be realized. For this reason, in addition to being able to be easily applied to the conventional direct-acting fixed valve system, as well as such a direct-acting fixed valve system, the rotation limit can be improved with a simple structure, There is no risk of shaft misalignment between the swing cam 13 and the drive shaft 11, and the control accuracy is excellent. Further, the rocker arm 17 and the links 15 and 18 are gathered around the drive shaft 11 and are compact as a whole and excellent in engine mounting. Further, many of the connecting portions between the members, such as the bearing portion of the drive eccentric cam 14 and the first link 15 and the bearing portion of the control eccentric cam 16 and the rocker arm 17, are in surface contact, and lubrication is achieved. In addition to being easy to perform, it does not require an urging means such as a return spring, so it has excellent durability and reliability.

  The phase changing mechanism 20 changes the rotational phase of the drive shaft 11 (camshaft in the case of a fixed valve system) with respect to the rotational phase of the crankshaft, thereby changing the center phase of the intake valve operating angle to the advance side or the retarded side. A type using a vane, a type using a helical spline, and the like are known.

  As an example, a hydraulically driven phase change mechanism 20 using a vane will be briefly described with reference to FIGS. 1 and 2. The phase changing mechanism 20 is fixed to or integrally formed with a timing pulley (or sprocket) 21, a housing 22 that rotates integrally with the timing pulley 21, a housing 22 that is rotatably accommodated in the housing 22, and a drive shaft. 11 (a camshaft in the case of a fixed valve) having a vane 23 fixed to or integrally formed with 11 and rotating integrally with the drive shaft 11. Rotational power is transmitted from the crankshaft to the timing pulley 21 and the housing 22 via a timing belt (or timing chain), and rotates around an axis in synchronization with the crankshaft (generally at a half speed). A pair of hydraulic chambers 25 and 26 are liquid-tightly defined inside the housing 22 with the vane portion 24 of the vane 23 interposed therebetween. By switching / adjusting the hydraulic pressure in these hydraulic chambers 25 and 26 by the electromagnetic switching valve 27 shown in FIG. 1, the relative phase between the vane 23 and the housing 22 is changed, and the drive shaft 11 relative to the crankshaft and the timing pulley 21 is changed. Change the phase. In addition, the code | symbol 28 of FIG. 1 is an oil pump as a hydraulic pressure source of working hydraulic pressure.

  3 to 6 show the configuration of the intake system collector 38 and its vicinity. As shown in FIG. 3, one end of intake ports 34 of a plurality of (four in this example) cylinders constituting the cylinder row is opened on the intake-side side wall 32 of the cylinder head 30. A mounting bracket 36 is fixed to the side wall 32 so as to cover the port opening 35 of the intake port 34. A single collector 38 is directly attached to the mounting bracket 36, and a plurality of intake branches 40 communicating with and connected to the plurality of intake ports 34 are projected into the collector 38.

  The collector 38 is composed of two members, a collector upper divided body 42 and a collector lower divided body 44 made of a light and inexpensive resin material, and an air cleaner 46 is interposed between the divided bodies 42 and 44. . That is, as shown in FIG. 6, with the air cleaner 46 and the gasket 48 sandwiched between the collector upper divided body 42 and the collector lower divided body 44, both the divided bodies 42 and 44 are detachably fixed by, for example, a clip 50. ing. It should be noted that an appropriate clip locking portion 52 is recessed in the clip mounting position in the divided bodies 42, 44, and in the other portions, as shown by the broken line H in FIG. Is not formed.

  As shown in FIG. 5, for example, the collector lower divided body 44 constituting most of the collector 38 has an upper flange portion 55 fastened and fixed to the mounting bracket 36 by a pair of upper bolts 54 and a pair of lower bolts. 56, the lower flange portion 57 is fastened and fixed to the cylinder head 30, the cylinder block 31, or their mounting members.

  As shown in FIG. 4, a cylindrical intake intake 58 is integrally formed in the collector upper divided body 42, and a pressure adjusting mechanism 110 is provided at or near the intake intake 58. This pressure adjustment mechanism 110 is provided to obtain the minimum negative pressure necessary for the EGR device, the evaporated fuel processing device, etc. of the engine rather than adjusting the intake air amount. The effect will be described later. A filter having a lower filtering function (coarse) than the air cleaner 46 may be attached to the upstream side of the pressure adjusting mechanism 110 so that large dust or the like is not caught in the pressure adjusting mechanism 110.

  As shown in FIG. 3, the collector lower divided body 44 extends in a cylindrical shape toward the inside of the collector 38, and a plurality of first branch constituting portions 68 constituting a part of the intake branch 40 and fuel to the intake port 34. It has a recess 72 for avoiding interference with the fuel injection valve 70 to inject, and a mounting plate portion 74 fixed to the mounting bracket 36 in a surface contact state, and these portions 68, 72, 74 are integrated. Is formed. The mounting plate portion 74 is relatively thicker than other portions in order to ensure mounting rigidity.

  The mounting bracket 36 is formed of a highly rigid aluminum alloy or the like, similar to the cylinder head 30, and the mounting of the cylindrical second branch constituting portion 76 constituting a part of each intake branch 40 and the fuel injection valve 70. It has a boss portion 78, and a mounting plate portion 80 interposed between the side wall 32 of the cylinder head 30 and the mounting plate portion 74 of the collector lower divided body 44, and these portions 76, 78, 80 are integrated. Is formed. The mounting bracket 36 is typically fastened and fixed to the side wall 32 of the cylinder head 30 by a plurality of bolts 82 as shown in FIG.

  The intake branch 40 means a cylindrical body that forms an intake passage from the port opening 35 of the intake port 34 to the bell mouth-shaped branch opening 84 that opens into the collector 38. In this example, the gasket 86 is used. The first branch constituent part 68 and the second branch constituent part 76 that are fitted through the first branch constituent part are configured.

  Thus, since the collector 38 is directly attached to the mounting bracket 36 attached to the side wall 32 of the cylinder head 30, for example, at the projecting end of the intake branch (or intake manifold) projecting from the cylinder head in the engine width direction. Compared with the case where the collector is attached, the support rigidity of the collector 38 is improved, and the vibration input acting on the collector 38 is also reduced. In addition, since the collector 38 is disposed close to the side wall 32 of the cylinder head 30 and the intake branch 40 is substantially built in the collector 38, the intake device is made compact, and its engine mountability is improved. To do.

  In order to realize such a layout, as described above, it is required to shorten the intake branch 40 and increase the capacity of the collector 38. What is the shortening of the intake branch 40 and the increase in the capacity of the collector 38? This can be achieved by using the variable valve mechanism described above that adjusts the intake air amount by changing the valve lift characteristic of the intake valve 1.

  Further, as shown in FIG. 3, the collector 38 has an engine vertical direction (vertical direction in FIG. 3) approximately along the side wall 32 of the cylinder head 30, and the dimension in the engine width direction ( It is set longer than the dimension in the left-right direction in FIG. That is, the collector 38 has a vertically long shape along the engine vertical direction (cylinder axis direction). For this reason, the amount of protrusion of the collector 38 in the engine width direction is suppressed, the dead space below the cylinder head 30 can be used effectively, and the support rigidity and engine mountability of the collector 38 are further improved.

  In addition, the air cleaner 46 is interposed between the detachable collector upper divided body 42 and the collector lower divided body 44, and a part of the intake branch 40 (first branch constituting unit 68) is provided in the collector lower divided body 44. Since the air cleaner 46 is formed above the branch opening 84 of the intake branch 40, the collector lower part 44, which constitutes the majority of the collector volume, is removed from the engine by removing the collector upper part 42. There is also an advantage that the air cleaner 46 can be easily replaced without being removed.

  By the way, in order to improve fuel consumption and output, when a valve overlap is set in which both the intake valve and the exhaust valve are opened, the combustion gas may flow backward to the intake side. If the backflowed combustion gas is directly applied to the air cleaner, the air cleaner may be damaged or deteriorated. Therefore, as shown in FIG. 3, the air cleaner 46 is disposed at a position deviated from the projecting direction of the intake branch 40 from which the combustion gas is discharged, specifically, substantially perpendicular to the projecting direction.

  Referring to FIG. 7, the pressure adjustment mechanism 110 includes a first diaphragm valve 121, a second diaphragm valve 122, and an electromagnetic valve 123. The first diaphragm valve 121 includes a diaphragm 126 that hermetically defines the positive pressure chamber 124 and the negative pressure chamber 125, and a spring 127 that biases the diaphragm 126 toward the positive pressure chamber 124. The movement is transmitted to the throttle (valve element) 120 via the links 136 and 137. The positive pressure chamber 124 communicates with the intake passage upstream of the throttle 120 in the intake flow direction (the direction of arrow A in the figure), and the internal pressure is almost atmospheric pressure. A negative pressure adjusted through a negative pressure passage 128 is introduced into the negative pressure chamber 125.

  As shown in FIG. 7A, since the differential pressure acting on the diaphragm 126 is small when the negative pressure introduced into the negative pressure chamber 125 is small, the diaphragm 126 is moved to the positive pressure chamber 124 side by the biasing force of the spring 127 (see FIG. And the throttle 120 is closed. On the other hand, when the negative pressure introduced into the negative pressure chamber 125 is large, as shown in FIG. 7C, the differential pressure acting on the diaphragm 126 increases, and the diaphragm 126 is on the negative pressure chamber 125 side (the upper side in the figure). ) And the throttle 120 is opened. Therefore, the throttle 120 is adjusted to an opening degree corresponding to the magnitude of the negative pressure introduced into the negative pressure chamber 125.

  The negative pressure passage 128 is connected to a vacuum pump (not shown) driven by an internal combustion engine (crankshaft), and one end of the atmospheric passage 129 is connected to the negative pressure passage 128 in the middle. The atmosphere passage 129 is a passage for introducing the atmosphere into the negative pressure passage 128, and a needle valve 130 of the second diaphragm valve 122 is disposed at a connection portion with the negative pressure passage 128.

  The second diaphragm valve 122 includes a diaphragm 133 that hermetically defines the positive pressure chamber 131 and the negative pressure chamber 132, and a spring 134 that biases the diaphragm 133 toward the positive pressure chamber 131. The positive pressure chamber 131 communicates with the atmosphere, and the internal pressure is almost atmospheric pressure. A negative pressure in the intake passage downstream of the throttle 120 is introduced into the negative pressure chamber 132 via the intake negative pressure passage 135. When the negative pressure downstream of the throttle 120 is small, the differential pressure acting on the diaphragm 133 is small, so that the diaphragm 133 is moved to the positive pressure chamber 131 side by the urging force of the spring 134 as shown in FIGS. The needle valve 130 attached to the diaphragm 133 moves in a direction to open the atmosphere passage 129 (direction to introduce the atmosphere into the negative pressure passage 128). On the other hand, when the negative pressure downstream of the throttle is large, the differential pressure acting on the diaphragm 133 increases, and as shown in FIG. 7B, the diaphragm 133 is displaced to the negative pressure chamber 132 side (upper side in the figure) The needle valve 130 moves in a direction to close the atmospheric passage 129. Therefore, the negative pressure in the negative pressure passage 128 is adjusted according to the magnitude of the negative pressure downstream of the throttle 120.

  By the action of the first diaphragm valve 121 and the second diaphragm valve 122 having such a simple structure that mechanically operate as described above, the downstream of the throttle 120, that is, the inside of the collector 38 is maintained at a predetermined negative pressure (for example, −50 mmHg). be able to. For this reason, a required negative pressure can be given to the EGR device and the evaporated fuel processing device.

  Further, at the time of full open output or the like, the solenoid valve 123 interposed in the atmosphere passage 129 is operated to shut off the atmosphere passage 129, so that the inside of the negative pressure passage 128 is independent of the operating state of the second diaphragm valve 122. The negative pressure increases, and the throttle 120 can be held in the fully open position to make the pressure inside the collector 38 almost atmospheric.

  With reference to FIGS. 8 and 1, in the first embodiment of the present invention, the collector 38 is provided with an atmosphere release mechanism 140. The air release mechanism 140 includes a communication hole 150 that is formed through the collector wall 141 that forms the collector lower divided body 44 of the collector 38, and a latch that is attached along the peripheral edge of the communication hole 150 in the collector wall 141. And a diaphragm-type lid 152 that closes the communication hole 150 in an airtight state by being airtightly engaged with the seal portion 151. A spring 153 is interposed between the collector wall 141 and the lid 152 in a compressed state, and both ends of the spring 153 are fixed to the collector wall 141 and the lid 152, respectively. In addition, a detection sensor 154 that detects that the lid 152 is in a locked state or a detached state is attached to the collector wall portion 141.

  FIG. 8A shows a state in which the pressure adjusting mechanism 110 is operating normally when the engine is stopped and during normal operation. In this case, since the negative pressure in the collector 38 is equal to or lower than a predetermined negative pressure (for example, −50 mmHg) that can be generated by the pressure adjusting mechanism 110, the lid 52 is against the urging force of the spring 153 and the negative pressure in the collector 38. The outer peripheral edge portion is held in a state of being locked by a seal portion 151 attached to the collector wall portion 141, and the inside of the collector 38 is maintained in an airtight state.

  FIG. 8B shows that the negative pressure in the collector 38 exceeds a predetermined negative pressure that can be generated by the pressure adjustment mechanism 110 during abnormal operation, that is, due to failure of the pressure adjustment mechanism 110 or deterioration over time. A predetermined excessive negative pressure state (for example, −several hundred mmHg) is shown. In this way, when the negative pressure in the collector 38 exceeds a predetermined limit value (set negative pressure), the lid 152 and the seal portion 151 are unlocked with the deformation of the diaphragm-type lid 152, etc. The lid 152 gets over the seal portion 151 and protrudes toward the inside of the collector 38. As a result, a space 155 is formed between the lid 152 and the collector wall 141, and the inside of the collector 38 is opened to the atmosphere through the space 155, that is, the atmosphere is released. Thus, once the atmosphere release mechanism 140 is activated, the lid 152 is held in the state shown in FIG. 8B by the self-elastic force of the spring 153, so that the inside of the collector 38 is reliably held in the atmosphere release state. The That is, the spring 153 has a function of keeping the inside of the collector 38 open to the atmosphere.

  As described above, if the inside of the collector is in an excessively negative pressure state for some reason, the atmosphere opening mechanism 140 operates quickly and the inside of the collector 38 is opened to the atmosphere. Therefore, the collector 38 is formed of a light and inexpensive resin material. However, it is possible to reliably prevent the collector 38 from being damaged by deformation due to an excessive negative pressure.

  Referring to FIG. 9, an ECU (engine control unit) 200 of this internal combustion engine includes a signal Ne from a crank angle sensor 201 that detects a phase of the crankshaft corresponding to the rotational speed of the internal combustion engine, an accelerator opening degree. The signal APO from the accelerator opening sensor 202 for detecting the signal, the signal rE from the potentiometer 203 for detecting the rotation angle of the control shaft 12, the signal rT from the phase sensor 204 for detecting the phase of the drive shaft 11, and the atmosphere release mechanism 140 A signal S or the like from the detection sensor 154 that detects that the operation has been performed is input. In the ECU 200, various control command values are calculated based on various programs, and these control command values are sent to the actuator 19, the electromagnetic switching valve 27, the electromagnetic valve 123, the fuel injection valve 70, the spark plug, and the like. For example, the advance angle / retard angle amount of the drive shaft 11 with respect to the rotation phase of the crankshaft is calculated based on the detection signals of the crank angle sensor 201 and the phase sensor 204, and the control shaft is calculated based on the advance angle / retard angle amount. A control command value including the feedback correction amount is output to the 12 actuators 19.

  FIG. 10 is a flowchart showing the flow of control according to the first embodiment. This flowchart is executed by the ECU 200 at predetermined intervals, for example. Here, only the control target value of one of the two changing mechanisms 10 and 20 for the operating angle changing mechanism 10 is different from that in the normal time when the atmosphere opening mechanism is operating abnormally. However, it is more preferable to change the target valve lift characteristics by changing the control target values of the two changing mechanisms 10 and 20 together.

  In S (step) 101, the engine rotational speed Ne, the accelerator opening APO, and the operation signal S of the air release mechanism are read. In S102, the actual rotation angle rE of the control shaft and the actual phase rT of the drive shaft are read. In S103, it is determined whether or not the operation signal S of the atmosphere release mechanism is zero. However, the sensor 154 outputs a signal 0 at the normal time when the atmosphere release mechanism is not operated, and outputs a signal 1 when the atmosphere release mechanism is operated. When it is determined that S = 0 (normal operation state), the process proceeds to S104 and subsequent steps, and a control command value is calculated based on a normal operating angle map as shown in FIG.

  That is, in S104, if it is determined that the current operating condition (Ne, APO) is within the operating region A corresponding to the low / medium load region of the engine, the process proceeds to S105 and the solenoid valve 123 of the pressure adjusting mechanism is opened. The valve signal is output. Thereby, the pressure inside the collector is adjusted to a predetermined constant negative pressure (−50 mmHg). In the subsequent S106, the target control shaft rotation angle tE is looked up from the normal operation angle map of FIG. 11A based on the engine rotation speed Ne and the accelerator opening APO. The operating angle map is a map in which the operating angle of the intake valve for obtaining the intake air amount corresponding to the operating conditions (Ne, APO) is stored as the rotation angle of the control shaft, and the value in the operating area A is the value inside the collector. Are matched under the condition that the pressure is a predetermined constant negative pressure.

  On the other hand, in S104, when it is determined that the current operating condition is not in the operating region A but in the operating region B corresponding to the high load region of the engine, the process proceeds to S107 and the electromagnetic valve 123 of the pressure adjusting mechanism is turned on. A valve closing signal is output. Thereby, the pressure inside the collector becomes almost atmospheric pressure. In the subsequent S108, the target control shaft rotation angle tE is looked up from the normal operation angle map of FIG. 11A based on the engine rotation speed Ne and the accelerator opening APO, as in the process of S106. However, the map stored values in the region B are matched under the condition that the pressure inside the collector is atmospheric pressure.

  If it is determined in S103 that S = 0 and not the atmospheric release mechanism 140 is operating abnormally, the process proceeds to S109, and a warning lamp is lit to warn the driver of the occurrence of the failure. In this embodiment, even if a failure occurs in the pressure adjustment mechanism and the atmospheric release mechanism is activated, an output that is substantially equivalent to that in the normal time can be secured using an operation angle map for an abnormal time as described later, In this case, evaporative fuel purge control or the like cannot be performed, and an immediate repair is required. Therefore, a warning lamp is lit to notify the driver of the occurrence of a failure.

  In subsequent S110, based on the engine rotational speed Ne and the accelerator opening APO, the target control shaft rotational angle tE is determined from the abnormal operating angle map of FIG. 11B, which is different from the normal operating angle map described above. Look up. The values stored in this map match the values in all the operation regions under the condition that the pressure inside the collector is atmospheric pressure. And it is set so that the engine output equivalent to the normal time is generated in all operating regions even in the event of an abnormality. That is, the operating angle (the stored value) of the operating angle map at the time of abnormality is equal in the operating condition corresponding to the operating region B when compared with the operating angle map (the stored value) at the normal time under the same operating condition. However, it is smaller under the operating conditions corresponding to the operating region A. If the intake air amount that matches the idle operation conditions cannot be obtained even if the minimum controllable operating angle is set as the target value, the fuel injection amount is preferably only during idle operation. To reduce the engine output.

  In S111, the target drive shaft phase tT is looked up from a phase map (not shown) based on the engine speed Ne and the accelerator opening APO. In S112, a control command value for eliminating a deviation between the target control shaft rotation angle tE and the actual rotation angle rE of the control shaft is calculated, and this control command value is output to the actuator 19. The control command value may be calculated by any method. For example, the proportional correction amount obtained by multiplying the deviation between tE and rE by the proportional gain, the integral correction amount obtained by multiplying the integral value of the deviation by the integral gain, and the deviation. The sum of the amount of change and the differential correction amount obtained by multiplying the differential gain by the differential gain is added to the previous command value to obtain a new command value. In S113, a control command value for eliminating the deviation between the target drive shaft phase tT and the actual phase rT of the drive shaft is calculated, and this control command value is output to the electromagnetic switching valve 27.

  By such control, when an abnormality occurs when the atmosphere release mechanism 140 is activated due to a failure of the pressure adjustment mechanism 110 or the like, the abnormality is promptly notified to the occupant by turning on a warning lamp, and a normal operation angle map is used. The engine output equivalent to the time can be secured.

  In the embodiments described below, the same components as those in the first embodiment are denoted by the same reference numerals, and redundant descriptions are omitted as appropriate.

  In the second embodiment shown in FIGS. 12 and 13, only the atmospheric release mechanism is changed as compared with the first embodiment described above. That is, the air release mechanism according to the second embodiment is configured by the strength weakening portion 160 in which a part of the wall portion of the collector 38 is partially weakened (weakened). The strength weakening portion 160 is formed by partially thinning a part of the collector wall portion 161 having a substantially uniform thickness forming the collector upper divided body 42, and is upstream of the air cleaner 46 in the intake air flow direction. Is arranged. And, when the negative pressure is excessive, the strength weakening portion 160 is cracked and cracked so that the inside of the collector 38 is opened to the atmosphere.

  According to such 2nd Embodiment, in addition to the effect similar to the said 1st Embodiment being obtained, an air release mechanism can be embodied without increasing a number of parts, and a structure is further simplified. Further, when repairing, it is only necessary to replace the collector upper divided body 42 provided with the strength weakening portion 160, and it is not necessary to replace the collector lower divided body 44 constituting most of the collector 38. Excellent workability.

  Further, since the strength weakening portion 160 constituting the atmosphere release mechanism is disposed upstream of the air cleaner, even if the strength weakening portion 160 is cracked, that is, even when the air release mechanism is activated, this strength weakening is performed. It is possible to reliably prevent debris from the portion 160 and dust mixed from the crack portion of the strength weakening portion 160 from being caught by the air cleaner 46 and entering the downstream side of the air cleaner 46, that is, the cylinder side.

  In the first embodiment as well, if the atmosphere release mechanism 140 is disposed in the collector upper divided body 42 on the upstream side of the air cleaner 46, the atmosphere release is performed after the operation of the atmosphere release mechanism 140, as in the second embodiment. It is possible to prevent dust or the like entering from the space 155 of the mechanism 140 from being captured by the air cleaner 46 and entering the cylinder side.

  The third embodiment shown in FIGS. 14 and 15 has a simple structure in which the atmosphere release mechanism (140, 160) is not provided. Instead, a pressure sensor 170 as a pressure detecting means for detecting the pressure inside the collector 38 is attached to the collector 38. The pressure in the collector 38 detected by the pressure sensor 170 is output to the ECU 200.

  FIG. 16 is a flowchart showing a flow of control according to the third embodiment, and is executed by the ECU 200 at predetermined time intervals, for example. In the third embodiment, the fail-safe control in the above negative pressure excessive state (abnormal state) is performed by controlling the fuel injection amount, and the control of the variable valve mechanisms 10 and 20 and the control of the electromagnetic valve 123 of the pressure adjustment mechanism 110. Performs the same control as normal. For example, the control of the operation angle of the intake valve (control of the rotation angle of the control shaft 12) by the operation angle changing mechanism 10 is always performed with reference to the normal operation angle map shown in FIG.

  In S201, the engine speed Ne, the accelerator opening APO, and the pressure P in the collector are read. The pressure P is an absolute pressure value. On the other hand, “negative pressure” corresponds to a differential pressure with respect to atmospheric pressure. For example, if the atmospheric pressure is 760 mmHg, the pressure becomes negative when the pressure P is smaller than 760 mmHg, and the negative pressure increases (the negative pressure develops) as the value P becomes smaller.

  In S202, it is determined whether or not the collector internal pressure P is smaller than the first set pressure Pth1. The first set pressure Pth1 is set to a value that is slightly larger (smaller as the negative pressure) than the limit pressure that causes problems such as deformation of the entire collector due to the developed negative pressure. The second embodiment substantially corresponds to the set negative pressure at which the atmospheric release mechanism operates.

  If it is determined in S202 that the collector internal pressure P is smaller than the first set pressure Pth1, the process proceeds to S203, and a warning lamp is lit to warn the driver of the occurrence of the failure. In subsequent S204, the fuel injection amount correction coefficient H is set to zero. Thus, when the fuel injection amount correction coefficient H becomes 0, the final fuel injection amount Ti becomes 0, and fuel injection is not performed (fuel cut). Such a fuel cut prevents the development of negative pressure due to a rise in rotation and promptly avoids damage to the collector due to excessive negative pressure.

  On the other hand, if it is determined in S202 that the collector internal pressure P is equal to or higher than the first set pressure Pth1, the process proceeds to S205, where the current operating condition (Ne, APO) is within the operating range A corresponding to the low / medium load range. Judge whether there is. The setting of the operation region and the like are the same as in the first embodiment. If it is determined in S205 that the current operation condition is within the operation region A, the process proceeds to S206, and it is determined whether or not the collector internal pressure P is smaller than the second set pressure Pth2. This second set pressure Pth2 is set to a value slightly smaller than the absolute pressure (710 mmHg) corresponding to the predetermined negative pressure (−50 mmHg) in the collector in the normal operation region A.

  If it is determined in S206 that the collector internal pressure P is smaller than the second set pressure Pth2, the process proceeds to S207 and the warning lamp is turned on. In subsequent S208, the collector internal pressure P [mmHg] detected at 710 [mmHg], which is the normal collector internal pressure, is divided to calculate the fuel injection amount correction coefficient H. If it is determined in S206 that the collector internal pressure P is equal to or higher than the second set pressure Pth2, the process proceeds to S209, and the fuel injection amount correction coefficient H is set to 1. That is, the fuel injection amount is not corrected based on the internal pressure P or the like.

  If it is determined in S205 that the current operation condition is not in the operation region A but in the region B corresponding to the high load region, the process proceeds to S210, and is the collector internal pressure P smaller than the third set pressure Pth3? Judge whether or not. The third set pressure Pth3 is set to a value slightly smaller than the normal pressure (atmospheric pressure, for example, 760 mmHg) in the operation region B. When the collector internal pressure P is smaller than the third set pressure Pth3, the process proceeds to S211 and the warning lamp is turned on. In subsequent S212, the collector internal pressure P [mmHg] detected at 760 [mmHg] which is the normal collector internal pressure is divided to calculate the fuel injection amount correction coefficient H. If it is determined in S210 that the collector internal pressure P is equal to or higher than the third set pressure Pth3, the process proceeds to S213, and the fuel injection amount correction coefficient H is set to 1. That is, the fuel injection amount is not corrected based on the detected pressure P or the like.

  In S214, the basic fuel injection amount Tp is calculated based on the engine speed Ne and the accelerator opening APO. Specifically, the intake air amount is calculated when there is no failure in the pressure adjustment mechanism and the target valve lift characteristic corresponding to Ne and APO is obtained, and the theoretical air-fuel ratio is realized with respect to this intake air amount. The amount of fuel injection to be performed is calculated as Tp. The intake air amount may be calculated based on the actual rotation angle rE of the control shaft and the actual phase rT of the drive shaft. In S215, the final fuel injection amount Ti is calculated by multiplying the basic fuel injection amount Tp by the fuel injection amount correction coefficient H.

  By performing such control, a warning is given to the occupant when the detected pressure P in the collector is smaller than the first set pressure Pth1, that is, when the negative pressure in the collector exceeds a predetermined set negative pressure. At the same time, the fuel injection is stopped (fuel cut) to prevent the negative pressure from developing due to the increased rotation, and the damage to the collector due to the excessive negative pressure can be avoided quickly. Further, even when the detected pressure P in the collector is smaller than the intended set pressures Pht2 and Pth3 (large as negative pressure), it is determined that the pressure adjustment mechanism 110 is not operating normally and a warning is issued. At the same time, since the fuel injection amount is corrected in accordance with the detected pressure P in the collector, the engine stability is improved.

  The first to third embodiments as described above deal with a failure of the pressure adjustment mechanism in which an excessive negative pressure is generated inside the collector, but on the contrary, the operation region A (see FIG. 11). A failure mode in which a predetermined negative pressure does not occur in (1) is also conceivable. Such a failure in an excessively low negative pressure state is less problematic than a failure in which excessive negative pressure is generated, but evaporative fuel purging control cannot be performed, and an immediate repair is required. There is no. Therefore, when the pressure P inside the collector is detected and this pressure P is larger than a predetermined fourth set pressure Pth4 (for example, a value slightly larger than 710 [mmHg]) in the operation region A, that is, the negative pressure inside the collector is Even in the case of an excessively low underpressure state, a warning lamp is preferably turned on.

  In addition, if such a fault in the underpressure state occurs, the intake air amount in the driving castle A increases from the normal time. Therefore, if the fuel injection amount is corrected accordingly, the engine output becomes excessive. If the fuel injection amount is not corrected, there arises a problem that the air-fuel ratio becomes lean. Therefore, even when a negative pressure excessive state failure occurs, as in the case of the negative pressure excessive state described above, a target valve lift characteristic different from the normal state (for example, an operating angle map at the time of abnormality shown in FIG. 11B). It is desirable to add control for reducing the intake air amount based on

  Preferably, in accordance with the engine operating state, the variable valve mechanisms 10 and 20 advance the intake valve opening timing from the intake top dead center and exhaust valve closing timing to perform internal EGR operation to reduce pump loss. And improve fuel economy. However, during a failure in which the pressure adjustment mechanism 110 has failed, such as when the negative pressure is excessively large or the negative pressure is excessively small, the pressure inside the collector 38 is smaller than that during normal operation when the pressure adjustment mechanism 110 is operating normally. Since the negative pressure fluctuates, the internal EGR rate also changes carelessly. For this reason, the intake air amount cannot be calculated accurately, and the fuel injection amount cannot be set accurately. Therefore, during such a failure, preferably, the variable valve mechanisms 10 and 20 are driven and controlled so that the opening timing of the intake valve is later than the closing timing of the exhaust valve, and the internal EGR operation is prohibited and the internal EGR rate is prohibited. This eliminates the calculation error of the intake air amount due to the fluctuation of the engine and stabilizes the engine operating state.

10 ... Working angle change mechanism (variable valve mechanism)
20 ... Phase change mechanism (variable valve mechanism)
38 ... Collector 110 ... Pressure adjustment mechanism 140 ... Air release mechanism 160 ... Strength weakening part (atmosphere release mechanism)
170 ... Pressure sensor (pressure detection means)
200 ... ECU (control means, fuel injection control means)

Claims (9)

A variable valve mechanism capable of continuously changing the intake air amount of the internal combustion engine by changing the valve lift characteristic of the intake valve;
A collector to which intake passages of a plurality of cylinders are connected;
A pressure adjusting mechanism for generating a predetermined negative pressure inside the collector;
An air intake device for an internal combustion engine, comprising: an air release mechanism that opens the interior of the collector to the atmosphere when the negative pressure inside the collector exceeds a predetermined negative pressure. 2. The intake system for an internal combustion engine according to claim 1, wherein the air release mechanism holds the inside of the collector in an air open state after its operation. The atmosphere release mechanism is composed of a strength weakening part in which a part of the wall of the collector is partially weakened. When the negative pressure is excessive, a crack occurs in the strength weakened part and the inside of the collector is opened to the atmosphere. The intake device for an internal combustion engine according to claim 2, wherein: The air release mechanism includes a communication hole formed through the collector wall, a lid that closes the communication hole, and a latch that locks the lid on the collector wall and holds the lid closed. 3. The intake device for an internal combustion engine according to claim 2, wherein the lid is released and the interior of the collector is opened to the atmosphere in the state where the negative pressure is excessive. A control means for setting a target valve lift characteristic of the intake valve based on the engine operating condition, and controlling the variable valve mechanism according to the target valve lift characteristic; a detection means for detecting the operation of the atmosphere release mechanism; With
5. The internal combustion engine according to claim 2, wherein the control means sets a target valve lift characteristic that is different before and after the operation of the atmosphere release mechanism is detected. 6. Intake device. 6. The intake device for an internal combustion engine according to claim 1, wherein an air cleaner is built in the collector, and the atmosphere release mechanism is disposed upstream of the air cleaner in the intake inflow direction. The pressure adjusting mechanism adjusts the negative pressure inside the collector to be substantially constant in a predetermined operating region, and sets the pressure inside the collector to substantially atmospheric pressure in a region other than the predetermined operating region. The intake device for an internal combustion engine according to any one of 1 to 6. A variable valve mechanism capable of continuously changing the intake air amount of the internal combustion engine by changing the valve lift characteristic of the intake valve;
A collector to which intake passages of a plurality of cylinders are connected;
A pressure adjusting mechanism for generating a predetermined negative pressure inside the collector;
Pressure detecting means for detecting the pressure inside the collector;
The fuel injection is stopped when the detected negative pressure inside the collector exceeds the predetermined set negative pressure larger than the predetermined negative pressure, and the fuel injection is stopped. The detected negative pressure inside the collector is the predetermined negative pressure and the predetermined negative pressure. An intake device for an internal combustion engine, comprising: a fuel injection control unit that corrects a fuel injection amount based on the predetermined negative pressure and the detected negative pressure when it is between a set negative pressure. The pressure adjusting mechanism adjusts the negative pressure inside the collector to be substantially constant in a predetermined operating region, and sets the pressure inside the collector to substantially atmospheric pressure in a region other than the predetermined operating region. The intake device for an internal combustion engine according to claim 8.

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