JP2007016696A - Variable valve gear for internal combustion engine and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable valve gear for an internal combustion engine and its control method, solving problems on the degradation of starting responsiveness and starting stability. <P>SOLUTION: In the control method, there are provided a reduction region A where a converting angle corresponding to a timing for opening/closing an intake valve is reduced with an increase in the amount of operation from an initial position and an increase region B where it is increased. The method comprises conversion from the reduction region A into the increase region B after starting the engine (Step 12), and prohibiting the conversion from the increase region B into the reduction region A after conversion (Step 13). Since there is no possibility of misidentifying the region, the control stability is improved and no need exists for a sensor or control processing to determine the region, resulting in simplified construction and control. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a variable valve operating apparatus for an internal combustion engine having a variable valve mechanism for changing a control amount corresponding to an opening / closing characteristic of an intake valve or an exhaust valve of the internal combustion engine according to an operation amount from an initial position of the operating body, and It relates to the control method.

As described in Patent Document 1 and Patent Document 2, control related to opening / closing characteristics such as opening / closing timing (valve timing), operating angle, and valve lift amount of an intake valve and an exhaust valve according to the operating state of the internal combustion engine Various variable valve mechanisms that change the amount have been proposed and partially put into practical use. Such a variable valve mechanism is generally configured such that the control amount changes according to the operation amount from the initial position of the operating body driven by the actuator. In many mechanisms, the control amount monotonously increases or decreases with respect to the change (increase or decrease) of the operation amount as in Patent Document 1 due to its structure.
JP-A-11-182214 JP 2003-314216 A

  When the engine starts, the appropriate control amount for the intake / exhaust valve opening / closing characteristics is not necessarily the limit value at both ends of the range that the control amount can take, and it is better to set an intermediate value excluding the limit value There is. For example, when idling, the intake valve opening / closing timing (control amount) is set to the most retarded value, which is the limit value, in order to reduce pump loss, etc., while at the time of engine start, the intake valve opening / closing timing is set to ensure starting stability. For example, the intermediate value that is advanced from the most retarded value is set. In such a case, in the mechanism in which the control amount changes monotonously with respect to the change in the operation amount as described above, the operation position of the operation body at the time of starting the engine is the limit position at both ends of the range that the operation body can take, That is, it is not a limit position that is mechanically locked by hitting the end face of the guide groove of the member, a stopper, or the like, but an intermediate position that excludes this limit position. For this reason, for example, as disclosed in Patent Document 1, it is necessary to separately provide an intermediate lock mechanism for stably mechanically holding the operating body at an intermediate position suitable for starting the engine. In addition, since a means for driving and controlling this is required, problems such as an increase in the number of parts, an increase in size, and an increase in cost remain. If the operating position when the engine is stopped is not at an intermediate position suitable for starting the engine, it is necessary to drive the operating body from the initial position to the starting intermediate position by an actuator when starting the engine. Decreasing and starting stability will be reduced.

  Patent Document 2 proposes a variable valve mechanism that changes the opening and closing timings of intake and exhaust valves using spiral guides (grooves) having different radial lengths depending on circumferential positions. In this mechanism, by appropriately setting the shape of the spiral guide as will be described later, even if the control amount for starting the engine is an intermediate value, the corresponding operation position for starting the engine can be changed. One limit position of the range, i.e., a mechanically locked position, which can typically coincide with the initial position when the engine is stopped. As a result, even if the control amount for starting the engine is an intermediate value, the initial position of the operating body can be set to an intermediate position corresponding to the intermediate value of the control amount. The engine start performance including start response and start stability can be remarkably improved while having a simple structure that is not required.

  However, when the control amount at the initial position of the operating body is set to an intermediate value in this way, inevitably, a decrease region in which the control amount decreases according to an increase in the operating amount from the initial position of the operating body, There are both increasing regions where the control amount increases, and in the control amount range where these decreasing regions and the increasing region overlap, the operating position of the operating body corresponding to the same control amount, that is, the operating amount from the initial position is There will be two. For this reason, in the configuration in which the operating body is driven and controlled according to the actual control amount that is the detection value of the control amount detected by the sensor or the like, there are two operating amounts corresponding to the actual control amount, so that the operating body is improved. The drive cannot be controlled. For example, when feedback control is performed with the control amount directed to the target value based on the actual control amount, the operation amount that is different from the actual one of the two operation amounts corresponding to the actual control amount is misidentified. If the control is continued, there is a possibility that the operating body is displaced in an unexpected direction and cannot be converged well to the target value. The present invention has been made in view of such problems.

  An actuator for driving the operating body, a variable valve mechanism for changing the control amount related to the opening / closing characteristics of the intake valve or the exhaust valve according to the operation amount from the initial position of the operating body, and the control amount Control amount detection means for detecting the actual control amount, and by controlling the operation of the actuator according to the actual control amount, with a simple configuration that does not require sensors that directly detect the operation amount The operation of the actuator can be controlled in accordance with the engine operating state such as the engine load and the engine speed. Typically, a control value target value is set based on the engine operating state, and feedback control based on a deviation between the target value and the actual control amount is performed.

  Further, a decrease region where the control amount decreases with an increase in the operation amount from the initial position for starting the engine and an increase region where the control amount increases with the increase in the operation amount are provided. Accordingly, since the change in the control amount relative to the change in the operation amount is not monotonously increasing or monotonically decreasing, as described above, even if the control amount for engine start is an intermediate value, The position can be set to the limit position of the variable range that is the mechanical locking position, that is, the initial position.

  And an area switching means for switching from the decreasing area to the increasing area after the engine is started, and an area switching prohibiting means for prohibiting switching from the increasing area to the decreasing area after switching to the increasing area by the area switching means. Have. That is, after switching to the increase area, the control amount is controlled using only the increase area.

  According to the present invention, after switching from the engine start to the increase region, switching from the increase region to the decrease region is prohibited, and control is performed using only the increase region. Since there is no mixing of the regions, that is, the operating body is not erroneously switched between the increase region and the decrease region, the control based on the actual control amount can be stably performed.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 schematically shows an example of a system configuration of an internal combustion engine 61 to which a variable valve operating apparatus according to the present invention is applied. A plurality of cylinders 63 are formed in the cylinder block 62 of the internal combustion engine 61, and combustion chambers 65 are defined above the pistons 64 that move up and down in each cylinder 63. The cylinder head 66 fixed on the cylinder block 62 includes an intake valve 68 that opens and closes an intake passage 67, an exhaust valve 70 that opens and closes an exhaust passage 69, and an ignition plug 71 that sparks and ignites an air-fuel mixture in the combustion chamber 65. And are arranged. In the intake passage 67, an air cleaner 72, an air flow meter 73 that detects the intake air amount, an electronically controlled throttle 74 that adjusts the intake air amount, and a fuel injection valve 76 that injects fuel into the intake port 75 in order from the upstream side. It is arranged. The opening degree of the throttle 74 is detected by a throttle opening degree sensor 77. In the exhaust passage 69, in order from the upstream side, an oxygen sensor 78 for detecting the air-fuel ratio of exhaust, catalysts 79 and 80 such as a three-way catalyst for purifying exhaust, and a muffler 81 for silencing the exhaust noise are provided. Is provided. A part of the exhaust gas is recirculated to the intake air passage 67 via the EGR passage 82, and the recirculation amount is adjusted by the EGR control valve 83. The temperature of the EGR gas is detected by the EGR temperature sensor 84. A fuel pump 87 that pumps fuel to the fuel pipe 86 and a pressure regulator 88 that maintains the fuel pressure at a predetermined pressure are disposed in the fuel tank 85. Further, a canister 89 for processing the evaporated fuel in the fuel tank 85 is provided. Further, a valve timing changing mechanism 60 that changes the conversion angle θ corresponding to the opening / closing timing of the intake valve 68 is provided as a variable valve mechanism that changes the opening / closing characteristics of the intake / exhaust valves. The conversion angle θ corresponds to the phase of the camshaft 1 with respect to the crankshaft 92, and by changing the conversion angle θ, the opening / closing timing (valve timing) of the intake valve changes, that is, retards / advances. The actual conversion angle tθ corresponding to the conversion angle θ is calculated based on detection signals from the camshaft position sensor 91 and the crankshaft position sensor 93.

  As sensors for detecting the engine operating state, a water temperature sensor 90 for detecting the engine water temperature, a camshaft position sensor 91 for detecting the rotational position of the intake camshaft 1, a crankshaft position sensor 93 for detecting the rotational position of the crankshaft 92, A knock sensor 94 that detects the occurrence of knocking, an accelerator position sensor 96 that detects the operation (opening degree) of the accelerator pedal 95, a current sensor 98 that detects the current value of the battery 97, and the like are provided. The engine control unit (engine control module: ECM) 100 has a function of storing and executing various control processes, and the throttle 74, fuel, and the like based on the engine operating state detected by the various sensors. In addition to the injection valve 76, the spark plug 71, the EGR control valve 83, and the like, a control signal is output to an actuator (operation force applying means 8) of the valve timing changing mechanism 60, which will be described later, and the throttle opening, fuel injection amount, fuel injection The timing, the ignition timing, the EGR amount, the conversion angle θ and the like are controlled.

  FIG. 2 is a cross-sectional view showing the valve timing changing mechanism 60. The basic structure of the mechanism 60 is well known as described in detail in Japanese Patent Application Laid-Open No. 2003-314216. Referring to FIGS. 1 and 2, the valve timing changing mechanism 60 is a driven shaft member (driven rotor) 3 that rotates integrally with the camshaft 1 and a drive that rotates in conjunction with the rotation of the crankshaft 92. A ring (drive rotator) 5, and an assembly angle operation mechanism 6 for changing and operating the conversion angle (assembly angle) θ corresponding to the relative rotation phase between the drive ring 5 and the driven shaft member 3; ,have.

  The driven shaft member 3 is integrally connected to the front end portion (left end portion in FIG. 2) of the camshaft 1 on the intake valve side rotatably supported by the cylinder head 66 of the internal combustion engine 61 by the cam bolt 2. In addition, the driven shaft member 3 is integrally formed with a flange wall 14 that projects outward in the radial direction at a base end portion that is abutted against the front end portion of the camshaft 1. A seal ring 34 is interposed between the outer peripheral portion of the flange wall 14 and the rear end portion of the drive ring 5. An oil supply hole 13 is formed in the driven shaft member 3, and the lubricating oil is supplied to the sliding surface between the drive ring 5 and the driven shaft member 3 through the supply hole 13.

  The drive ring 5 is a timing sprocket 4 (power transmission) connected to a crankshaft 92 via a chain (not shown) so as to be able to transmit power via an inner cylindrical portion 10a that is rotatably mounted on the outer periphery of the driven shaft member 3. A substantially cylindrical outer cylindrical portion 5a provided with a portion), and a substantially disc-shaped / doughnut-shaped supporting portion 10 integrally connected to the outer periphery of the inner cylindrical portion 10a and the inner periphery of the outer cylindrical portion 5a. Have. Two radial slits 11 extending in the radial direction are formed in the support portion 10, and the radial slit 11 functions as a radial guide for guiding a movable guide portion 12 described later. Note that the radial slit is not necessarily formed along the radial direction of the support portion, and may be formed so as to be substantially along the radial direction of the support portion.

  The assembly angle operation mechanism 6 is arranged coaxially with the drive ring 5 and the driven shaft member 3, and is rotated by an operation force applied from an operation force applying means 8 as an actuator, and a drive ring 5 and two links 15 that link the driven shaft member 3, and rotational power is transmitted from the drive ring 5 to the driven shaft member 3 via the link 15. The intermediate rotating body 7 is formed with a spiral groove 24 whose radial length smoothly changes along the circumferential position. One end of each link 15 is swingably supported and connected to the flange wall 14 of the driven shaft member 3 by a pin 16. That is, each link 15 can swing around the pin 16.

  At the other end of each link 15, a movable guide portion 12 that engages with the spiral groove 24 through the radial slit 11 is provided. Specifically, a boss portion 17 that protrudes forward in the axial direction is integrally formed at the other end of the link 15. Each boss portion 17 is formed in a cylindrical shape, and is slidably fitted into each corresponding radial slit 11 of the support portion 10. Since each boss portion 17 is engaged with the radial slit 11 of the support portion 10 and is connected to a position separated from the rotation center of the driven shaft member 3 via the link 15, each boss portion 17 is When the drive ring 5 and the driven shaft member 3 are displaced along the radial slit 11 in response to an external force, the drive ring 5 and the driven shaft member 3 rotate relative to each other in the direction and angle corresponding to the displacement (operation amount) of each boss portion 17. Move. A circular holding hole 18 opened to the front side (opposite side of the camshaft 1) is provided from the boss portion 17 on the tip end side (the other end side) of each link 15 to the link main body portion. A base portion of a retainer 20 for holding 19 and a coil spring 21 as a biasing means for biasing the retainer 20 forward are accommodated.

  An intermediate rotating body 7 is rotatably supported via a bearing 23 in front of the support position of the support portion 10 of the driven shaft member 3. Two spiral grooves 24 (spiral guides) are formed in a semicircular cross section on the rear surface of the intermediate rotating body 7 facing the front surface of the support portion 10 with a predetermined gap. Each spiral groove 24 is set so that the radial length smoothly changes according to the circumferential position. Then, a ball 19 held by each boss portion 17 is engaged with each spiral groove 24 of the intermediate rotator 7 so as to roll freely. Here, since each link 15 is engaged with the spiral groove 24 in a state where the boss portion 17 on the distal end side is guided and engaged with the radial slit 11 of the support portion 10, the intermediate rotating body 7 is When the sphere 19 is guided by the spiral groove 24 and rolls by rotating relative to the drive ring 5, each boss portion 17 has the radial slit 11 in the direction and amount corresponding to the relative rotation of the intermediate rotating body 7. Displacement along As described above, the rotation phase of the driven shaft member 3 with respect to the drive ring 5 is changed by the radial slit 11 of the support portion 10, the intermediate rotating body 7 having the spiral groove 24, the link 15 having the movable guide portion 12, and the like. A corner operation mechanism 6 is configured.

  The operating force applying means 8 includes a cylindrical housing 25 integrally coupled to the drive ring 5, a cylindrical permanent magnet block 26 coupled to the inner peripheral surface of the housing 25, and a retainer plate 27 on the intermediate rotating body 7. And a cylindrical yoke block 28 coupled so as to be integrally rotatable therewith, and an electromagnetic coil block 30 fixedly installed via a rubber elastic body 29 in a VTC cover 9 which is a non-rotating member. A pair of electromagnetic coils 31a and 31b provided in the electromagnetic coil block 30 is connected to a drive circuit (not shown) including an excitation circuit and a pulse distribution circuit. The engine control unit 100 calculates a target value tθ of the conversion angle θ based on various input signals such as a crank angle, a cam angle, an engine speed, and an engine load, and a control signal corresponding to the target value tθ. For example, an ON-OFF signal corresponding to the duty ratio is output to the drive circuit.

  The permanent magnet block 26 has a configuration in which a plurality of magnetic poles extending in the axial direction are magnetized so that different magnetic poles alternate along the circumferential direction. The yoke block 28 has a plurality of pole tooth rings (not shown) made of a metal with high permeability, and the plurality of pole teeth of each pole tooth ring face the magnetic pole surface of the permanent magnet block 26 via an air gap. is doing. In the electromagnetic coil block 30, the magnetic input / output portion by the electromagnetic coils 31 a and 31 b is opposed to the annular base portion of each pole tooth ring of the yoke block 28 through an air gap.

  The operating force applying means 8 is basically a stepping motor, but by changing the duty ratio of the ON-OFF signal that excites the electromagnetic coils 31a and 31b, the magnetic poles of the pole teeth of the yoke block 28 become electromagnetic coils. The block 30 is continuously changed in a non-contact state, so that the yoke block 28 and the permanent magnet block 26 can be rotated relative to each other as desired regardless of the rotation of the yoke block 28 and the permanent magnet block 26.

  The electromagnetic coils 31a and 31b generate a magnetic field according to the duty ratio of the ON-OFF signal output from the engine control unit 100 to the drive circuits of the electromagnetic coils 31a and 31b, and the yoke block 28 and the intermediate rotating body 7 are driven by the drive ring. 5 is relatively rotated in a predetermined direction (delayed side or advanced side). As a result, each sphere 19 rolls in the spiral groove 24 and the corresponding boss portion 17 is displaced outward along the radial slit 11. The assembly angle of the driven shaft member 3 is changed. As a result, the rotation phase of the crankshaft and the camshaft 1, that is, the conversion angle θ is changed. That is, the conversion angle θ corresponding to the opening / closing timing of the intake valve continuously changes according to the displacement of the movable guide portion 12 driven by the operating force applying means 8 via the intermediate rotator 7.

  FIG. 3 shows the relationship between the operation amount S and the conversion angle θ. The operating amount S is a displacement from the initial position of the operating body driven by the actuator 8 in a broad sense, and specifically, from the one end 24A that is the initial position Smin of the ball 19 of the movable guide portion 12 in the spiral groove 24. Corresponds to displacement (angle). The conversion angle θ is a control amount corresponding to the open / close characteristics of the intake / exhaust valves in a broad sense. Here, the open / close timing of the intake valve, more specifically, the rotational phase of the camshaft 1 with respect to the crankshaft 92, and more specifically, Specifically, this corresponds to the conversion angle from the most retarded angle value θmin that is the initial value of the driven shaft member 3 with respect to the drive ring 5. Therefore, the opening / closing timing of the intake valve is retarded as the conversion angle θ is small, and advanced as the conversion angle θ is large. The conversion angle θ is proportional to the radial distance ΔR from the center O of the movable guide portion 12, and the conversion angle θ increases as the radial distance ΔR decreases. The center O is an axis that is common to all of the driven shaft member 3, the drive ring 5, and the intermediate rotating body 7, that is, the rotation center.

  The radial slit 11 is formed with a margin larger than the moving range of the movable guide portion 12 so that the movable guide portion 12 can move over the entire length of the other end 24B from the one end 24A of the spiral groove 24. Therefore, the entire length of the spiral groove 24 is the movable range ΔSall of the operation amount S, and both ends 24A and 24B of the spiral groove 24 correspond to the initial position Smin and the maximum operation position Smax that are the limit positions at both ends of the movable range ΔSall. At these limit positions, the sphere 19 is abutted against the end faces of both ends 24A and 24B of the spiral groove 24, and is in a state of being mechanically and stably locked. In a state where the electromagnetic coils 31a and 31b are not energized, such as when the engine is stopped, that is, in an initial state where the duty ratio of the ON-OFF signal is 0 (zero), it is movable by the valve reaction force acting on the camshaft 1 or the like. The guide portion 12 is always held at the initial position Smin, which is the minimum operating position where the guide portion 12 is mechanically locked.

  FIG. 3A shows a comparative example in which the conversion angle θ monotonously increases (changes) with respect to the increase in the operation amount S, and FIG. This corresponds to an example of the present invention in which both a decrease region A where the angle θ decreases and an increase region B where the conversion angle θ increases exist. As shown in FIG. 3B, the spiral groove 24 is provided with a section in which the radial length ΔR increases and a section in which the radial length ΔR decreases from the one end 24A to the other end 24B. The increasing section corresponds to the decreasing area A, and the decreasing section corresponds to the increasing area B. By appropriately setting the shape of the spiral groove 24 in this way, a characteristic that combines the decrease region A and the increase region B is realized while the conversion angle θ is uniquely changed according to the operation amount S. can do.

  In the comparative example having the monotone increasing characteristic, the conversion angle θ at the initial position Smin necessarily becomes the minimum value θmin. On the other hand, in the configuration having both the decrease area A and the increase area B, the conversion angle θ at the initial position Smin is an intermediate value θγ excluding the limit values θmin and θmax, that is, an intermediate suitable for engine start. A typical value θγ can be obtained. As a result, it is not necessary to drive the operating body from the initial position to the starting intermediate position when starting the engine as described above, and it is also necessary to use an intermediate lock mechanism or the like that holds the operating body at an intermediate position suitable for starting. Therefore, it is possible to achieve practically great effects such as simplification, miniaturization, and cost reduction while improving the start response and start stability.

  However, in the conversion angle range Δθγ in which both the decrease region A and the increase region B overlap, there are two operation amounts S, that is, operation positions corresponding to one conversion angle θ, and therefore the actuator 8 based on the actual conversion angle rθ. When driving is controlled, if the decrease area A and the increase area B are misidentified, the operating body may be displaced in an unexpected direction. If the operation amount S can be directly detected using a sensor or the like, such a problem will not occur. However, it is difficult to provide such a sensor, and the structure is complicated and large. This is not preferable because it causes increase in cost and cost.

  Therefore, in an embodiment described later, after switching from the decrease area A to the increase area B after starting the engine, switching from the increase area B to the decrease area A is prohibited until the engine is stopped. That is, after switching to the increase region B, the valve timing (conversion angle θ) is controlled using only the increase region B that covers the entire control range Δθall (see FIG. 3). By properly using the decrease area A and the increase area B in this way, the decrease area A and the increase area B are not misidentified, and the control can be stably performed based on the actual control amount. Control processing such as area determination between the area A and the increase area B can be simplified.

  FIG. 4 shows a first setting example of valve timing mainly aimed at improving fuel efficiency. At the time of engine start (A), in order to ensure starting stability, the intake valve opening timing IVO is set near the top dead center, and the intake valve closing timing IVC is set to a limit value on the retard side at which the engine can be started. Set near sIVO. On the other hand, at the time of idling and low load (B), since fuel efficiency improvement using the EGR effect due to valve overlap is not expected, the intake valve closing timing IVC is set to the most retarded angle position, and the start delay angle limit sIVO Will be further retarded to reduce compression work and improve fuel efficiency.

  FIG. 5 shows a second setting example of valve timing mainly aimed at improving the output. As in the example of FIG. 4, when starting the engine, in order to ensure starting stability, the intake valve opening timing IVO is set near the top dead center, and the intake valve closing timing IVC is set near the retardable limit sIVO that can be started. Set to. In the high speed range, the intake valve closing timing IVC is set to the most retarded position, and the retarded angle is further retarded from the retardable limit sIVO that can be started, and the intake air amount is increased using intake inertia to improve the output.

  In the first setting example and the second setting example of the valve timing, the setting of the valve timing at the initial position Smin, that is, the conversion angle θ is set to an intermediate conversion angle θγ at the time of starting (A), so that the engine is started. The actuator 8 can be started easily and stably without being substantially driven, and as shown in FIGS. 4 and 5, the intake valve closing timing IVC at the time of idling / low load or high rotation. Can be set so as to be more retarded than the retarded limit sIVC, and fuel consumption and output can be improved.

  FIG. 6 is a flowchart showing the flow of region switching control according to the first embodiment suitable for the first setting example and the second setting example. This routine is stored and executed by the control unit 100. In step (denoted as “S” in the figure) 11, it is determined whether the engine start has been completed. This determination can be performed using, for example, a well-known initial explosion / complete explosion determination. As described above, when the engine is stopped before the engine is started, the movable guide portion 12 is held at the initial position Smin that is the minimum operating position where the movable guide portion 12 is mechanically locked by the valve reaction force acting on the camshaft 1. Therefore, the engine is started at the initial position Smin or the decrease region A in the vicinity thereof.

  If it is determined that the engine start has been completed, the process proceeds from step 11 to step 12 where the movable guide portion 12 is driven by the actuator 8 to quickly switch from the decrease area A to the increase area B. Normally, after the engine is started, the engine shifts to the idle region, so that the increased region B is converted to the operating position corresponding to the idle region. In the following step 13, the area switching from the increasing area B to the decreasing area A is prohibited until the engine is stopped. That is, after switching to the increase area B, the conversion angle θ is controlled using only the increase area B. As an example of prohibition of area switching to the decrease area A, for example, after the switching to the increase area B, the actual conversion angle tθ may be prohibited from being equal to or less than the most retarded angle position θmin or a lower limit value in the vicinity thereof.

  FIG. 7 shows a third setting example of the valve timing aimed mainly at exhaust purification, in particular, reduction of the amount of unburned HC (hydrocarbon) emission at the time of cold start. At the time of engine start (A), the intake valve opening timing IVO is advanced from the top dead center TDC and the exhaust valve closing timing EVC, and an exhaust request O / L that is a predetermined amount of overlap is given, thereby In addition to the action of promoting vaporization, it is possible to reduce the amount of HC discharged at the start of the cold machine by confining high-concentration HC in the cylinder and reburning it. Further, the engine speed is set higher in the cold state, that is, in the idle state during the warm-up operation, that is, in the first idle state (B) than in the normal idle state after the warm-up operation (C). As with the engine start (A), combustion stability can be ensured even when a valve overlap (exhaust request O / L) is applied. Therefore, by providing the valve overlap (exhaust request O / L) in this way, the HC emission amount in the cold state is reduced.

  On the other hand, at the idling time (C) after the warm-up, the engine speed is lower than at the first idling time (B), and it is difficult to ensure the desired combustion stability if the valve overlap is applied. The intake valve opening timing IVO is delayed as compared with the above-described engine start time (A) and first idle time (B), and this IVO is set in the vicinity of the top dead center TDC. In the third setting example, similarly to the first and second setting examples, the setting of the valve timing at the initial position Smin, that is, the conversion angle θ is set to the intermediate conversion angle θγ at the start (A). When starting the engine, the actuator 8 can be started easily and stably without substantially driving, and the intake valve closing timing IVC is set to be higher than that at the start (A) at the time of idling after warming up (C). The retarded setting can be made, and stable idle operation after warm-up can be performed.

  FIG. 8 is a flowchart showing the flow of area switching control according to the second embodiment suitable for the third setting example. The same processing contents as those in the first embodiment of FIG. 6 are denoted by the same reference numerals, and redundant description will be omitted as appropriate. If it is determined in step 11 that the engine start has been completed, the process proceeds to step 11A to determine whether the engine is in a cold state. This determination is made based on the engine water temperature detected by the water temperature sensor 90, the oil temperature detected by the oil temperature sensor, or the outside air temperature detected by the outside air temperature sensor. Specifically, the detected temperature is a predetermined temperature. It is determined whether the temperature is equal to or lower than T ° C. When the engine is not originally in the cold state or when the warm-up operation is completed, the process proceeds from step 11A to step 12 to switch from the decrease area A to the increase area B. In step 13, the area switching from the increasing area B to the decreasing area A is prohibited until the engine stops. That is, after switching to the increase area B, the conversion angle θ is controlled using only the increase area B.

  Thus, in the second embodiment, at the time of cold start, the valve timing (conversion angle) is controlled using only the decrease region A until the warm-up operation is completed, and when the warm-up operation is completed, the decrease region is reached. Switching from A to the increase region B is performed, and thereafter, the valve timing is controlled using only the increase region B until the engine is stopped. As in the first embodiment, it is also possible to switch to the increase region B immediately after the start of the cold machine, but in this case, the valve overlap set once in the transition period immediately after the start of the cold machine to the first idle. After the amount is decreased, it is increased again, which may lead to wasteful energy consumption and a decrease in engine stability. Further, when the increase region B is used during the first idling, there is a possibility that the valve overlap is excessively given and the exhaust performance is lowered.

  As in this embodiment, by using only the decrease region A from the start of cold operation until the end of warm-up operation, wasteful energy consumption and engine stability deterioration associated with the region conversion described above may be caused. In addition, since the valve overlap at the time of the first idle (B) is limited to the exhaust request O / L or less at the start, there is no possibility that the valve overlap is excessively given and the exhaust performance is deteriorated.

  Next, a characteristic configuration that can be grasped from the above embodiment and its function and effect will be described. However, the present invention is not limited to the configuration of the embodiment given the reference numerals, and includes various modifications and changes without departing from the spirit thereof.

  (1) The opening / closing characteristics of the intake valve 68 or the exhaust valve 70 according to the actuator (operation force applying means) 8 for driving the operating body (movable guide portion 12) and the operation amount S from the initial position Smin of the operating body. A variable valve mechanism (valve timing changing mechanism) 60 that changes the control amount (conversion angle) θ related to the control amount, and control amount detection means (camshaft position sensor 91) that detects the actual control amount rθ corresponding to the control amount θ. , A crankshaft position sensor 93), and the operation of the actuator 8 can be controlled according to the engine operating state based on the actual control amount rθ. For example, the engine control unit 100 calculates the target value tθ of the control amount θ based on the engine load, the engine speed, etc., and performs feedback control based on the deviation between the target value tθ and the actual control amount rθ.

  Further, a decrease area A in which the control amount θ decreases with respect to an increase in the operation amount S from the initial position Smin for starting the engine and an increase area B in which the control amount increases are provided. That is, in the variable valve mechanism 60 according to the present invention, the change in the control amount θ with respect to the change in the operation amount S is not monotonous but is reduced, although the conversion angle θ is uniquely changed according to the operation amount S. A characteristic in which both the area A and the increase area B exist can be realized. Therefore, by setting the control amount θ at the initial position Smin to an intermediate value θγ suitable for engine start, the start response, start stability, etc. can be achieved with a simple and inexpensive configuration that does not require an intermediate lock mechanism or the like. The engine starting performance can be significantly improved.

  Then, an area conversion means (step 12) for converting from the decrease area A to the increase area B after the engine is started, and after the conversion to the increase area B by the area conversion means, conversion from the increase area B to the decrease area A is prohibited. Area conversion prohibiting means (step 13).

  Thus, by prohibiting the conversion to the decrease area A after the conversion to the increase area B, there is no possibility of misidentifying the area, so that the control stability is improved and the sensor and control for determining the area No processing is required, and its configuration and control are simplified.

  (2) For example, in the first setting example aimed at improving fuel efficiency (see FIG. 4) and the second setting example aimed at improving output (see FIG. 5), the engine is preferably used as in the first embodiment shown in FIG. By switching from the decrease area A to the increase area B immediately after the start is completed, the control stability can be improved immediately after the engine start is completed.

  (3) In the third setting example aiming at exhaust purification as shown in FIG. 7, preferably from the decrease region A to the increase region after the warm-up operation is completed at the time of cold start, as in the second example shown in FIG. Switch to B. As a result, useless region conversion is suppressed, and it is possible to avoid excessive valve overlap during cold machine idle (first idle) operation.

  (4) A preferable example of the variable valve mechanism having both the decrease region A and the increase region B is the spiral valve timing changing mechanism 60 that changes the opening / closing timing of the intake valve or the exhaust valve, as described above. The valve timing changing mechanism 60 rotates in conjunction with a drive rotating body (drive ring) 5 that rotates in conjunction with a crankshaft 92 of the internal combustion engine 61 and a camshaft 1 for driving an intake valve or an exhaust valve. A driven rotator (driven shaft member) 3, a spiral guide 24 having a different radial length according to the circumferential position is formed, an intermediate rotator 7 driven in the rotational direction by an actuator 8, and one end of a driven rotator 5 or a link 15 supported so as to be swingable on one of the driven rotators 3. On the other side of the link 15, there is a movable guide portion 12 that is displaceably engaged with both the radial guide 11 extending in the radial direction formed on the other of the driving rotary body 5 or the driven rotary body 3 and the spiral guide 24. Provided. The operation amount S corresponds to the displacement of the movable guide portion 12 from the one end 24 </ b> A of the spiral guide 24, and the conversion angle θ corresponds to a relative conversion angle of the driven rotor 3 with respect to the drive rotor 5.

  In such a spiral guide type valve timing changing mechanism 60, by appropriately setting the shape of the spiral guide 24, the characteristic of the change in the control amount θ with respect to the change in the operation amount S is represented by the decrease section A and the increase section B. Both can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS The system block diagram which shows simply an example of the variable valve operating apparatus of the internal combustion engine which concerns on this invention. Sectional drawing which shows the spiral guide type | formula valve timing change mechanism as an example of the variable valve mechanism based on this invention. (A) is a comparative example in which the conversion angle increases monotonously, (B) is related to an example of the present invention having both a decrease region and an increase region, the upper part is a characteristic diagram showing the relationship between the operation amount and the conversion angle, and the lower part is the above The block diagram which shows the principal part of a valve timing change mechanism. The characteristic view which shows the 1st setting example of the valve timing which mainly aimed at the fuel consumption improvement. The characteristic view which shows the 2nd example of a valve timing which aimed mainly at the output improvement. The flowchart which shows the flow of the area | region switching control based on 1st Example of this invention. The characteristic view which shows the 3rd example of a valve timing mainly aimed at exhaust gas purification. The flowchart which shows the flow of the area | region switching control which concerns on 2nd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Camshaft 3 ... Driven shaft member (driven rotating body)
5 ... Drive ring (drive rotating body)
7 ... Intermediate rotator 8 ... Operating force applying means (actuator)
11 ... Radial slit (radial guide)
12 ... Movable guide (actuator)
24 ... spiral groove (spiral guide)
60. Valve timing changing mechanism (variable valve mechanism)
100: Engine control unit

Claims (5)

An actuator for driving the operating body, a variable valve mechanism for changing the control amount related to the opening / closing characteristics of the intake valve or the exhaust valve according to the operation amount from the initial position of the operating body, and the control amount A variable amount control device for an internal combustion engine having control amount detection means for detecting an actual control amount, and capable of controlling the operation of the actuator according to the engine operating state based on the actual control amount,
A decrease region where the control amount decreases with respect to an increase in the operation amount from the initial position for starting the engine, and an increase region where the control amount increases with respect to the increase in the operation amount are provided,
And area switching means for switching from the decrease area to the increase area after the engine start,
Area switching prohibiting means for prohibiting switching from the increasing area to the decreasing area after switching to the increasing area by the area switching means;
A variable valve operating apparatus for an internal combustion engine, comprising:   2. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the region switching means performs switching from a decreasing region to an increasing region immediately after completion of engine starting.   The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the region switching means performs switching from the decrease region to the increase region after the warm-up operation is completed at the time of cold start. The variable valve mechanism is a valve timing changing mechanism for changing the opening / closing timing of an intake valve or an exhaust valve,
This valve timing change mechanism
A drive rotor that rotates in conjunction with the crankshaft of the internal combustion engine;
A driven rotating body that rotates in conjunction with a camshaft for driving an intake valve or an exhaust valve;
A spiral guide having a different radial length according to the circumferential position is formed, and an intermediate rotating body driven in the rotational direction by the actuator;
A link having one end swingably supported by one of the driving rotating body and the driven rotating body;
A radial guide formed on the other end of the drive rotary body or the driven rotary body and extending in the radial direction; and a movable guide portion that displaceably engages both of the spiral guides. The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein the operation amount corresponds to a displacement of the movable guide portion from one end of the spiral guide. An actuator for driving the operating body, a variable valve mechanism for changing the control amount related to the opening / closing characteristics of the intake valve or the exhaust valve according to the operation amount from the initial position of the operating body, and the control amount A control amount detecting means for detecting an actual control amount, and a control method for a variable valve operating apparatus for an internal combustion engine capable of controlling an operation of an actuator according to an engine operating state based on the actual control amount,
A decrease region where the control amount decreases with respect to an increase in the operation amount from the initial position for starting the engine, and an increase region where the control amount increases with respect to the increase in the operation amount are provided,
A control method for a variable valve operating apparatus for an internal combustion engine, wherein after the engine is started, switching from a decreasing region to an increasing region is performed, and after this switching, the control amount is controlled using only the increasing region.

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