JP4507933B2 - Multi-cylinder engine controller - Google Patents

Description

  The present invention relates to a control device for a multi-cylinder engine, and more particularly to a control device for a multi-cylinder engine provided with a pulse generator that generates an impulse (a high-pressure pressure wave introduced into a cylinder).

  Conventionally, various technologies for improving volumetric efficiency have been developed in a control device for a multi-cylinder engine provided with a surge tank of an intake manifold and a branch pipe branched from the surge tank and connected to an intake port of each cylinder. .

  For example, Patent Document 1 discloses a technique in which a plurality of intake passages having different passage lengths are provided for each intake port, and these intake passages are selectively communicated with a surge tank by a switching valve.

  On the other hand, Non-Patent Document 1 discloses a technique for increasing torque in a low operation region by impulse. In that configuration, an electromagnetic valve that strokes in the direction of the path of the branch pipe is provided in the middle of the branch pipe of the intake manifold, and until the middle of the intake stroke, the solenoid valve is closed to form a negative pressure, and the bottom dead center of the intake stroke A configuration is disclosed in which air is rapidly supplied into a cylinder by opening a solenoid valve in the vicinity.

Patent Document 2 and Non-Patent Document 2 disclose a device that generates a pulse using a flap valve as a device that generates an impulse.
JP 2003-41939 A JP 2000-248946 A Impulse charging boosts torque at low speed, Findlay Publications “European Automotive Design” February 2004 issue Development of an Actuator for a Fast Moving Flap for impulse Charging, Findlay Publications “European Automotive Design” January 2003 issue

  In order to improve the output performance while suppressing the fuel consumption of the engine, it is necessary to ensure sufficient volume efficiency while suppressing the pumping loss over the entire operation range.

  However, in the pulse generator described above, volume efficiency is increased, so that the output is improved, but a large negative pressure is generated when the pulse generator is opened, so that the pumping loss is also increased and the fuel consumption is reduced. For this reason, simply using the pulse generator cannot balance the fuel consumption and the output corresponding to all the operation areas.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a control device for a multi-cylinder engine that can balance fuel consumption and output in accordance with an operation region.

  In order to solve the above-described problems, the present invention corresponds to an intake pipe that supplies air to each intake port of a plurality of cylinders, a collecting portion that opens at an upstream end of each intake pipe, and an intake stroke of each cylinder. An engine for detecting the rotational speed of an engine in a control device for a multi-cylinder engine having a pulse generator that opens during the intake stroke within a valve opening period of the intake port and generates a pressure wave in the cylinder The rotation number detecting means, the volume portion communicating with the intake pipe, the volume portion opening / closing mechanism for opening and closing the communicating portion between the volume portion and the intake pipe, and the operation of the pulse generator based on the detection of the engine speed detection means And a control means for controlling the opening / closing operation of the volume portion opening / closing mechanism, and the intake passage length from the intake port downstream end of each intake pipe to the volume portion is dynamic in a high-speed operation region of a first predetermined rotation speed or higher. Set to a length that allows supercharging. The length of the intake passage from the downstream end of the intake port of each intake pipe to the collecting portion is a length that allows dynamic supercharging in a medium speed operation region that is less than the first predetermined rotational speed and is equal to or higher than a second predetermined rotational speed. And the control means controls the volume part opening / closing mechanism so as to open the volume part at the first predetermined rotation speed or more, and in the operation region less than the second predetermined rotation speed, the pulse generator This is a control device for a multi-cylinder engine.

  In this aspect, in a high-speed operation region where the engine speed is equal to or higher than the first predetermined speed, the volume portion is opened, thereby causing dynamic supercharging from the downstream end of the intake port of each intake pipe to the volume portion. It becomes possible to make it. For this reason, the volume efficiency in a high-speed driving | operation area | region improves. The dynamic supercharging may be inertia supercharging or resonance supercharging. Here, the inertia supercharging means that the pressure wave generated during the intake stroke in each cylinder is reversed and reflected by a surge tank or the like, and acts on the own cylinder at the end of the intake stroke to increase the charging efficiency. Dynamic effect. Resonance supercharging refers to a dynamic effect that enhances charging efficiency by resonating intake pressure oscillations occurring in a plurality of cylinders. However, when each intake passage length is set corresponding to inertial supercharging as dynamic supercharging, the distance can be shortened compared to resonance supercharging. Next, in the medium speed operation region from the first predetermined rotation speed to the second predetermined rotation speed, the volume portion is closed, so that the dynamic range between the downstream end of each intake port of each intake pipe and the collecting portion is obtained. It is possible to cause supercharging. For this reason, the volumetric efficiency in the medium speed operation region is improved. Further, in the low speed operation region that is less than the second predetermined rotation speed, a pressure wave can be generated in the intake pipe by operating the pulse generator while the volume portion remains closed. For this reason, the volumetric efficiency in the low speed operation region is improved.

  In a preferred aspect, the control means stops the operation of the pulse generator at least in the operation region from the second predetermined rotation speed to the first predetermined rotation speed. In this aspect, in the medium and high speed operation region, pressure waves are not generated, and it is possible to actively utilize the dynamic supercharging of the intake passage by providing the volume portion or the collecting portion.

  In a preferred aspect, the volume portion is constituted by a communication passage that communicates each intake pipe. In this aspect, since the intake passage length can be reliably switched by the opening / closing operation of the volume portion, it is possible to actively utilize the dynamic supercharging of the intake passage in the medium to high speed operation region.

  In a preferred embodiment, engine load detection means for detecting engine load and inputting it to the control means is provided, and the control means opens the volume portion even at a second predetermined rotational speed or less in the partial load region. In this aspect, in the fully open operation region where the engine is heavily loaded, a high volumetric efficiency can be obtained due to the supercharging effect by the pulse generator, while in the other partial load regions, the volume portion is opened, thereby causing the pulse. It is possible to quickly cancel the effect of generating the pressure wave by the generator and improve the fuel consumption. In particular, the in-cylinder pressure by the pulse generator can be quickly increased in combination with the fact that the volume portion is constituted by a communication path that communicates each intake pipe. For this reason, in a low-speed operation region where the engine speed is low, in a partial load region that does not require a large output, it is possible to reduce the pumping loss due to the pulse generator and improve the fuel efficiency.

  In a preferred aspect, the pulse generator has a variable valve opening mechanism capable of changing a valve opening timing, and the control means opens the pulse generator as the engine speed approaches a second predetermined speed. The variable valve opening mechanism is controlled so as to advance the valve timing. In this aspect, as the engine speed increases to the second predetermined speed, the valve opening timing of the pulse generator approaches the valve opening timing of the intake valve, so that the generated pressure wave also weakens, Pumping loss can be reduced and fuel consumption can be improved. In addition, since the generated pressure wave is weakened, the dynamic supercharging (inertia supercharging or resonance supercharging) in the intake pipe is relatively increased, and the volumetric efficiency in the cylinder is kept high. Is possible.

  In a preferred aspect, the pulse generator is a rotary valve that is housed in the collecting portion and rotates in synchronization with the crankshaft of the engine. In this aspect, a rotary valve that rotates in synchronization with the crankshaft is employed as the pulse generator, so that the pressure wave is generated in the cylinder at a desired timing by reliably synchronizing the frequency without receiving a large intake resistance. Can be generated. It becomes possible to equip the pulse generator which generates a pressure wave, without inhibiting the dynamic supercharging by providing a gathering part or a volume part.

  In a preferred aspect, the pulse generator is a rotary valve that rotates in synchronization with a crankshaft, the diameter of the rotary valve is set larger than the intake pipe cross-sectional width, and the upstream end of each intake pipe is a rotary valve. The single independent intake from the downstream end of the intake port to the opening of the rotary valve for a single stroke volume of each cylinder is arranged so as to face the opening formed in the peripheral surface of the cylinder. The ratio of the passage volume is set in the range of 70% to 130%. Also in this embodiment, a rotary valve that rotates in synchronization with the crankshaft is adopted as the pulse generator, so that the pressure is tuned to the cylinder at a desired timing by reliably synchronizing the frequency without receiving a large intake resistance. Waves can be generated. Further, since the diameter of the rotary valve is set larger than the intake pipe cross-sectional width, the intake pipe can be opened and closed at a high peripheral speed, and a strong pressure wave can be generated. Further, the rotary valve is configured such that the ratio of the single independent intake passage volume from the downstream end of the intake port to the opening of the rotary valve to the single stroke volume of each cylinder is in the range of 70% to 130%. Is set. This setting range is a range found by the present inventors through simulation as a result of diligent research. As will be described in detail later, the volume efficiency in the medium speed operation region can be improved to about 90% or more. is there. The ratio of the single intake passage volume from the downstream end of the intake port to the opening of the rotary valve with respect to the single stroke volume of each cylinder is referred to as “intake passage / stroke volume ratio” in this specification. Even if the intake passage / stroke volume ratio exceeds 130%, the volumetric efficiency is not necessarily lowered. However, in that case, since the intake passage becomes longer, the response to the torque improvement tends to decrease. Therefore, even if the torque during steady running can be increased, the torque may not necessarily be improved in a transient state during acceleration. On the other hand, when the intake passage / stroke volume ratio falls below 70%, the air amount necessary for the cylinder cannot be secured, so that the response is increased, but the volume efficiency is lowered. Therefore, in this aspect, the intake passage / stroke volume ratio is set from 70% to 130%. As a result, not only the torque at the steady state but also the torque in the transient state at the time of acceleration can be efficiently increased. The limitation of “70% to 130%” is not intended to exclude variations due to measurement errors and individual differences that are unavoidable in carrying out the invention.

  In a preferred aspect, the intake passage length from the intake port downstream end of each intake pipe to the volume portion is set to a length capable of inertia supercharging in the high speed operation region, and the intake port downstream end of each intake pipe is The intake passage length to the collecting portion is set to a length that allows inertia supercharging in the medium speed operation region. In this aspect, each intake passage length can be set short, so that the intake system can be made compact.

  As described above, according to the present invention, since a suitable supercharging effect can be obtained in all driving regions, there is a remarkable effect that fuel efficiency and output can be balanced according to the driving regions.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a right side view of a four-cycle spark-ignition multi-cylinder engine according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view taken along line AA of FIG. FIG. 3 is a perspective view schematically showing a main part of the present embodiment.

  Referring to the drawings, the engine 10 integrally includes a cylinder block 11 and a cylinder head 12 integrated on the upper portion of the cylinder block 11. The engine 10 is provided with first to fourth cylinders 12A to 12D, and a piston 4 connected to the crankshaft 3 is fitted into each of the cylinders 12A to 12D so that a combustion chamber is provided above the piston 4. 15 is formed.

  A spark plug 16 is fixed to the cylinder head 12 for each combustion chamber 15 of each of the cylinders 12A to 12D. Each spark plug 16 is installed such that its tip faces the corresponding combustion chamber 15 from the top.

  The cylinder head 12 is formed with an intake port 17 and an exhaust port 18 that open toward the combustion chamber 15 for each of the cylinders 12A to 12D, and an intake valve 19 is provided at the ports 17 and 18, respectively. And an exhaust valve 20 are respectively provided.

  Each intake port 17 is provided with a fuel injection valve 21. The fuel injection valve 21 incorporates a needle valve and a solenoid.

  An exhaust manifold (not shown) is connected to the exhaust port 18. An exhaust gas purification catalyst is provided in the exhaust passage downstream of the exhaust manifold assembly. This exhaust gas purification catalyst is formed of, for example, a so-called three-way catalyst in which the purification rate of HC, CO and NOx is extremely high when the air-fuel ratio of the exhaust is in the vicinity of the theoretical air-fuel ratio. As is generally known, this exhaust gas purification catalyst comprising a three-way catalyst is more effective than HC, CO, and NOx when the air-fuel ratio of the exhaust gas is near the stoichiometric air-fuel ratio (that is, the excess air ratio λ = 1). And high purification performance.

  The intake valve 19 and the exhaust valve 20 are configured to open and close the intake port 17 and the exhaust port 18 in synchronization with a predetermined phase difference by the camshafts 22 and 23 for the intake valve and the exhaust valve supported by the engine 10. Has been. The camshafts 22 and 23 are connected to a cam sprocket gear (not shown), and the cam sprocket gear receives power from a cam pulley 30 via a timing belt (not shown) (see FIG. 3). The cam pulley 30 is attached to the front surface of the engine 10 so as to be rotatable about an axis parallel to the crankshaft 3. On the other hand, an output pulley 32 attached to the front side of the engine 10 is fixed to the crankshaft 3, and both pulleys 30, 32 are configured to be synchronized with each other by a timing belt 34.

  The camshafts 22 and 23 are provided with variable valve timing mechanisms 24 and 25 that change the opening and closing timing by adjusting the rotation phase. As a result, the intake valve 19 can change the phase with respect to the crank angle.

  The intake device 40 according to the present embodiment includes an intake manifold 41 fixed to a side portion of the engine 10 and a rotary valve 50 as a pulse generator or PGV (Pulse Generating Valve) built in the intake manifold 41. is doing.

  The intake manifold 41 is fixed to the engine 10 via a support member (not shown), and a surge tank 42 as a collective portion extending horizontally in the front-rear direction of the engine 10 (the direction in which the cylinders 12A to 12D are arranged) The first to fourth branch intake pipes 43A to 43D are integrally formed as intake pipes connected to the surge tank 42 and forming the intake passages PH11 to PH14 separated from each other. A throttle body 44 is fixed to the rear end portion of the surge tank 42, and a throttle valve (not shown) is built in the throttle body 44.

  The surge tank 42 is a substantially cylindrical member, and by communicating with the branch intake pipes 43A to 43D, the surge tank 42 absorbs the differential pressure of each branch intake pipe 43A to 43D, and has a function of preventing abnormal noise and sensor malfunction. To fulfill. In the present embodiment, the length SL of the surge tank 42 in the cylinder row direction is set to be shorter than the interval DL on the downstream end side in the cylinder row direction of the branch intake pipes 43A to 43D described below. (See FIG. 1).

  Each of the branch intake pipes 43A to 43D is provided for each of the cylinders 12A to 12D, and communicates the corresponding cylinders 12A to 12D with the surge tank 42 in a state of being substantially L-shaped when viewed from the front. In the illustrated embodiment, each of the branch intake pipes 43A to 43D has passage lengths of the intake passages PH11 to PH14 (in this embodiment, the length from the intake port 17 to the peripheral surface 51 of the rotary valve 50 in the surge tank 42). Are set to the same length. The length of each of the intake passages PH11 to PH14 is set within 500 mm, thereby improving the response to torque by a rotary valve 50 described later. Further, the “intake passage / stroke volume ratio” (the ratio of the single intake passage volume from the downstream end of the intake port 17 to the openings 52 and 53 of the rotary valve 50 with respect to the single stroke volume of each cylinder) is 70 percent. It is set in the range of 130 percent or less (the length of the intake passage is 500 mm or less). This volume is determined so as to correspond to the natural frequency at which the intake air resonates in a medium speed operation region (3500 rpm or more) R2 of the engine. As a result, the natural frequency tunes and resonates in a relatively medium speed region, so that the valve opening time of the intake valve 19 can be secured in that region, and the passage length is set in the medium speed operation region R2 of the engine. It is possible to increase the volumetric efficiency by exerting the inertia supercharging effect due to.

  The rotary valve 50 is a cylindrical member, and is rotatably disposed in a state where the outer peripheral surface 51 is in sliding contact with the inner peripheral surface of the surge tank 42.

  Referring to FIG. 3, an input gear 54 </ b> A is provided concentrically at the front end portion of the rotary valve 50. The input gear 54A meshes with an output gear 54B provided concentrically with the cam pulley 30 so that power is transmitted from the crankshaft 3 at a ratio of 1: 0.5 via the output gear 54B. It has become. In other words, the rotary valve 50 is synchronized with the cam pulley 30 at a ratio of 1: 1. A pair of openings 52 and 53 are formed on the peripheral surface of the rotary valve 50 to communicate the inside of the surge tank 42 and the branch intake pipes 43A to 43D. The openings 52 and 53 are 180 degrees out of phase in the circumferential direction, and the front opening 52 is shifted upstream in the rotational direction with respect to the rear opening 53 in the axial direction. In the figure, 55 is an idler.

  In the illustrated embodiment, a rotary valve advance mechanism 56 is provided between the rotary valve 50 and the input gear 54A. The rotary valve advance mechanism 56 basically uses an input gear 54A and a rotary valve by using a rotation phase control device (see JP-A-11-107718) previously proposed by the present applicant. This is a mechanism for forming a phase difference between the rotary valve 50 and the valve opening timing of the rotary valve 50. The rotary valve advance mechanism 56 is driven and controlled by an OCV (Oil Control Valve) system 57 as shown in FIG. Further, as shown in FIG. 1, a PGV angle sensor 58 is attached to the rotary valve advance mechanism 56 in order to detect the phase of the rotary valve 50.

  The illustrated engine is an in-line four-cylinder engine, and when the cylinders are first to fourth cylinders 12A to 12D in order from the front of the engine 10, the order of reaching the intake stroke is the first cylinder 12A and the third cylinder. 12C, the fourth cylinder 12D, and the second cylinder 12B are set. As a result, when the first cylinder 12A reaches the intake stroke, the relationship between each cylinder and the stroke is as shown in Table 1.

  Therefore, in the present embodiment, the first branch intake pipe 43A and the second branch intake pipe 43B are arranged so as to be opposed to the opening 52 of the rotary valve 50 with a phase shifted downstream in the rotational direction. At the same time, the third branch intake pipe 43C and the fourth branch intake pipe 43D are arranged so as to be opposed to the opening 53 in the rotational direction upstream side and shifted in the rotational direction downstream side.

  More specifically, the second branch intake pipe 43B connected to the second cylinder 12B and the first branch intake pipe 43A connected to the first cylinder 12A are located upstream at positions where they can face the front opening 52. A third branch intake pipe 43C connected to the third cylinder 12C and a fourth branch intake pipe 43D connected to the fourth cylinder 12D are fixed to the surge tank 42 with a phase shifted by 90 ° from the side. Are fixed to the surge tank 42 at a position that can be opposed to the rear opening 53 with the phase shifted by 90 ° in order from the upstream side. Further, the first branch intake pipe 43A and the fourth branch intake pipe 43D (and hence the second branch intake pipe 43B and the third branch intake pipe 43C) are arranged in the same phase in the circumferential direction of the surge tank 42. Therefore, in this configuration, the branch intake pipes 43A to 43D can be opened and closed at a predetermined timing regardless of the engine speed, and the branch intake pipes 43A to 43D are made equal in length and compact. Will contribute. As a result, the intake passages PH11 to PH14 can be shortened as much as possible, and an intake structure with high response to torque improvement can be configured. Further, as described above, the length SL of the surge tank 42 in the cylinder row direction is set to be shorter than the interval DL on the downstream end side in the cylinder row direction of each of the branched intake pipes 43A to 43D described below. (See FIG. 1), the upstream ends of the branch intake pipes 43A to 43D are converged in the cylinder row direction as compared with the downstream ends. For this reason, in this embodiment, it has the structure where the response with respect to a torque improvement becomes very high.

  FIG. 4 is an enlarged cross-sectional view of the main part of FIG.

  With reference to the figure, the diameter D of the rotary valve 50 is set larger than the cross-sectional width of each branch intake pipe 43A-43D. By rotating the rotary valve 50 in synchronization with the crankshaft 3, the time for opening the branch intake pipes 43A to 43D corresponding to the openings 52 and 53 is shortened. In addition, since the rotary valve 50 is rotated to supply air to the branch intake pipes 43A to 43D facing the peripheral surface through the openings 52 and 53 formed on the peripheral surface, air pulsation can be suppressed. The occurrence of abnormal noise is also reduced.

  Furthermore, the valve closing angle θ between the openings 52 and 53 formed in the rotary valve 50 is set to 120 °, for example. By setting the valve opening start timing to the first half of the intake stroke, the intake valve 19 Even if the intake port 17 is opened, the rotary valve 50 remains in the state of shielding the surge tank 42, so that the negative pressure is generated in the corresponding branch intake pipe 43A (˜43D) by the intake stroke until the rotary valve 50 is opened. Will occur.

  FIG. 5 is a partially enlarged view showing an essential part of FIG.

  Referring to FIGS. 4 and 5, each branch intake pipe 43 </ b> A to 43 </ b> D is provided with a VIS (Variable Induction System) 60.

  The VIS 60 is a volume tube 61 as a volume portion extending in parallel with the crankshaft 3, a communication tube 62 that connects the volume tube 61 and each of the branch intake tubes 43 </ b> A to 43 </ b> D, and an open / close mechanism that opens and closes the communication tube 62. And a VIS valve 63. In the illustrated example, the volume tube 61 is a member that also functions as a communication passage that communicates each of the branched intake passages 43A to 43D. The VIS valves 63 are connected to the same drive shaft 64 and are configured to be simultaneously opened and closed by a VIS valve actuator 65 that drives the drive shaft 64. In the illustrated embodiment, the intake passage length Lf from the downstream end of each intake port 17 to the volume pipe 61 is dynamically supercharged in a high-speed operation region R3 equal to or greater than a first predetermined rotation speed (for example, 4500 rpm) Nf (this In the embodiment, it is set to a length capable of inertia supercharging). On the other hand, the intake passage length Ls from the downstream end of each intake port 17 to the rotary valve 50 is a medium speed operation region R2 of a second predetermined rotational speed (for example, 3800 rpm) Ns which is smaller than the first predetermined rotational speed Nf. The length is set so as to allow dynamic supercharging (in this embodiment, inertial supercharging). As a result, each of the branch intake pipes 43A to 43D corresponds to the natural frequency at which the intake air tunes and resonates at the first predetermined rotation speed Nf when the VIS valve actuator 65 opens the VIS valve 63, and the high speed operation region R3. In the state where the inertia supercharging effect in the engine is increased and the VIS valve actuator 65 closes the VIS valve 63, it corresponds to the natural frequency at which the intake air tunes and resonates at the second predetermined rotation speed Ns, and the medium speed operation is performed. The inertial supercharging effect in the region R2 can be enhanced.

With reference to FIG. 2, the engine 10 is provided with a pair of engine crank angle sensors 66. Each engine crank angle sensor 66 is disposed around the crankshaft 3 with a predetermined phase difference, and the engine speed is detected based on a detection signal output from one engine crank angle sensor 66, and The rotation direction and rotation angle of the crankshaft 3 are detected based on detection signals output from both engine crank angle sensors 66. Further, in order to detect the operating state of the engine 10, an engine water temperature sensor 67 that detects the temperature of the cooling water of the engine 10, an accelerator opening sensor 68 as engine load detection means, and exhaust gas discharged from the exhaust port 18. O ₂ sensor 69 is provided for detecting the amount of oxygen.

  Further, an EGR system 70 for returning a part of the burned gas discharged to the exhaust port 18 to the intake port 17 is provided.

  FIG. 6 is a block diagram according to the present embodiment.

Referring to FIG. 1, ECU 100 for controlling driving of engine 10 is a unit having a microprocessor, a memory, an input unit, and an output unit. A PGV angle sensor 58 that detects the phase of the rotary valve 50, an engine crank angle sensor 66, an engine water temperature sensor 67, an accelerator opening sensor 68, and an O ₂ sensor 69 are connected to the input portion of the ECU 100 as input elements. . Further, an output portion of the ECU 100 includes an ignition plug 16, a fuel injection valve 21, variable valve timing mechanisms 24 and 25 for the intake valve 19 and the exhaust valve 20, a rotary valve advance mechanism 56 (specifically, an OCV system 57), The VIS valve actuator 65 is connected as an output element.

  Next, a control map stored in the memory of the ECU 100 will be described.

  FIG. 7 is a graph showing the torque with respect to the engine speed N, the phase of the rotary valve 50, and the opening / closing operation of the VIS valve 63.

  Referring to FIG. 7, when the rotary valve 50 is used as the engine output characteristic, the torque characteristic is as shown by a curve C1. Further, when the VIS valve 63 is closed, the torque characteristic, that is, when the intake passage length of each of the branch intake pipes 43A to 43D is Ls, the curve C2 is obtained. Further, when the characteristics of the torque when the VIS valve 63 is opened, that is, when the intake passage length of each of the branch intake pipes 43A to 43D is Lf, the curve C3 is obtained. Therefore, the low speed operation region in which the operation region is supercharged by the rotary valve 50 is R1, the intake passage length is Ls, the medium speed operation region in which inertial supercharging is generated is R2, and the intake passage length is Lf, and the high speed is generated in inertial supercharging. The operating range is set to R3, the engine speed when the VIS valve 63 is closed in advance by experiment or the like is set as the first predetermined speed Nf, and the engine speed lower than this is set as the second predetermined speed Ns. 7 is created and stored in the memory of the ECU 100.

  By the way, even in the low speed operation region R1, it may not always be a good idea to operate the rotary valve 50.

  FIG. 8 is a graph showing the relationship between torque and fuel consumption.

  Referring to FIG. 8, when the rotary valve 50 is operating, the fuel consumption becomes worse as the pumping loss increases than when the rotary valve 50 is not operating. Therefore, in the partial load region of the engine 10, the VIS valve 63 is opened to improve fuel efficiency even in the low speed operation region R1, and the supercharging effect by the rotary valve 50 only in the high load region (engine fully open region). The ECU 100 is set so that

  Next, the operation of the above-described embodiment will be described with reference to the flowcharts in FIG.

  Referring to FIG. 9, in the above configuration, first, after engine 10 starts to start (step S1), ECU 100 reads each detected value from an input element connected to the input unit (step S2).

  Next, a target value of the rotary valve 50 as PGV is set based on these detected values (step S3). In the illustrated embodiment, the phase of the rotary valve 50 when the engine is started is set to the most advanced state (that is, the OFF state). In this state, the ECU 100 controls the OCV system 57 of the rotary valve advance mechanism 56 to determine the valve opening timing of the rotary valve 50. As shown in FIG. 7, on the low speed side, the rotary valve 50 is set to a retarded angle (a state in which the valve opening timing is most delayed with respect to the valve opening timing of the intake valve 19), while the engine speed is set. As N rises, the valve is advanced (a state in which the valve opening timing approaches the valve opening timing of the intake valve 19).

  Next, the ECU 100 detects whether or not the engine speed N has reached the second predetermined speed Ns (step S4). If the engine rotational speed N is less than the second predetermined rotational speed Ns, the ECU 100 determines that the engine 10 is operating in the low speed operation region R1, and whether the accelerator opening is in the partial load region. It is determined whether or not (step S5). If the operating state is the partial load region, the ECU 100 refers to the flag F for operating the VIS valve 63 (step S6). The domain of the flag F is alternatively set so that the value for closing the VIS valve 63 is 0 and the value for opening is 1. In step S6, when the value of the flag F is 0, the ECU 100 opens the VIS valve 63 (step S7). Here, as a means for stopping the operation of the rotary valve 50, in step S7 of this embodiment, the rotary valve advance mechanism 56 is not directly controlled, but the VIS valve 63 is opened and the volume pipe 61 is passed through. Since a method of communicating each of the branch intake pipes 43A to 43D is employed, it is possible to exhibit high responsiveness compared to the case where the rotary valve 50 having a large inertia or air resistance is directly driven. Thereby, the supercharging effect by the impulse generation by the rotary valve 50 is canceled, and the fuel consumption can be improved.

  Thereafter, the ECU 100 updates the value of the flag F to 1 (step S8). If the value of the flag F is 1 in step S6, the process proceeds to the next step as it is.

  In step S4, when the engine speed is equal to or higher than the second predetermined speed Ns, the ECU 100 performs stop setting of the rotary valve 50 (step 9). That is, as shown in FIG. 7, at the second predetermined rotation speed Ns or more, the valve opening timing of the rotary valve 50 is advanced so that the rotary valve 50 opens during the intake stroke period.

  Next, the ECU 100 determines whether or not the engine speed N is less than the first predetermined speed Nf (step S10). If the engine speed N is equal to or higher than the first predetermined speed Nf, the ECU 100 determines that the engine 10 is operating in the high speed operation region R3, and proceeds to step S6. For this reason, in the high speed operation region R3, as the VIS valve 63 is opened, each branch intake pipe 43A to 43D has a dynamic supercharging (inertia supercharging) effect with a short intake passage length Lf suitable for the high speed operation region R3. Can be obtained.

  On the other hand, if the operating state is the full load range in step S5, or if the engine speed N is less than the first predetermined speed Nf in step S10, the ECU 100 determines whether the value of the flag F is 1 or not. Whether or not (step S11) and the value of the flag F is 1, the VIS valve 63 is closed (step S12), and the value of the flag F is updated to 0 (step S13). If the value of the flag F is 0, the process proceeds to the next step as it is.

  Referring to FIG. 10, after the flow of FIG. 9 is completed, ECU 100 operates rotary valve 50 based on the setting in step S3 or step S9 of the flow (step S14). In this case, in the operating state based on the setting in step S9, the rotary valve 50 is substantially stopped. When the engine speed N is equal to or higher than the first predetermined speed Nf, the VIS valve 63 is open and the rotary valve 50 is substantially stopped regardless of the opening / closing timing. Thereafter, the fuel injection valve 21 is driven for a set period at a predetermined time to inject fuel (step S15), and the spark plug 16 is driven at a predetermined time to burn the air-fuel mixture in the combustion chamber 15 (step S15). S16). Thereafter, the ECU 100 ends the process when the engine 10 stops operating, and returns to step S2 when continuing the operation (step S17).

  As described above, in the present embodiment, in the high speed operation region R3 where the engine speed N is equal to or higher than the first predetermined speed Nf, the VIS valve 63 is opened and the volume pipe 61 is communicated with the branch intake pipes 43A to 43D. By doing so, it is possible to cause inertia supercharging between the downstream end of the intake port 17 in each of the branched intake pipes 43A to 43D and the volume pipe 61. For this reason, the volumetric efficiency in high-speed driving | operation area | region R3 improves. Next, in the medium speed operation region R2 from the first predetermined rotation speed Nf to the second predetermined rotation speed Ns, the VIS valve 63 closes the volume pipe 61, whereby the intake ports of the branch intake pipes 43A to 43D. 17 It is possible to cause inertia supercharging between the downstream end and the surge tank 42. For this reason, the volumetric efficiency in a medium speed rotation area improves. Further, in the low speed operation region R1 that is less than the second predetermined rotation speed Ns, the rotary valve 50 is operated with the volume pipe 61 closed, thereby generating impulses in the branch intake pipes 43A to 43D. be able to. For this reason, the volumetric efficiency in the low-speed driving | operation area | region R1 improves.

  In the present embodiment, the ECU 100 stops the operation of the rotary valve 50 at least in the medium speed operation region R2 from the second predetermined rotation speed Ns to the first predetermined rotation speed Nf. For this reason, in the present embodiment, impulses are not generated in the medium and high speed operation regions R2 and R3, and it is possible to positively utilize the inertia supercharging of the intake passage due to the provision of the volume tube 61 or the surge tank 42. .

  Further, in the present embodiment, the volume pipe 61 is constituted by a communication path that communicates the branched intake pipes 43A to 43D. For this reason, in the present embodiment, the intake passage length can be switched reliably by the opening / closing operation of the VIS valve 63 that opens and closes the volume pipe 61, so that the inertia excess by the branch intake pipes 43A to 43D in the medium and high speed operation regions R2 and R3. The salary can be actively used.

  Further, in the present embodiment, an accelerator opening sensor 68 is provided as an engine load detecting means for detecting an engine load and inputting the detected engine load to the ECU 100. The ECU 100 has a volume even at a second predetermined rotational speed Ns or less in a partial load region. The tube 61 is opened. Therefore, in the present embodiment, in the fully open operation region where the engine 10 is heavily loaded, high volumetric efficiency can be obtained by the supercharging effect by the rotary valve 50, while in the other partial load regions, the volume tube 61 is provided. By opening, it is possible to quickly cancel the impulse generation effect by the rotary valve 50 and improve fuel consumption. In particular, the in-cylinder pressure by the rotary valve 50 can be quickly increased in combination with the volume pipe 61 being configured by a communication path that communicates with the branch intake pipes 43A to 43D. For this reason, in the low speed operation region R1 where the engine speed N is low, in the partial load region where a large output is not required, the pumping loss due to the rotary valve 50 can be reduced and the fuel consumption can be improved.

  Further, in the present embodiment, the rotary valve 50 has a rotary valve advance mechanism 56 as a variable valve opening mechanism capable of changing the valve opening timing, and the ECU 100 has an engine speed N of a second predetermined rotation. The rotary valve advance mechanism 56 is controlled so that the valve opening timing of the rotary valve 50 is advanced (closer to the valve opening timing of the intake valve 19) as it approaches several Ns. For this reason, in this embodiment, as the engine speed N increases to the second predetermined speed Ns, the valve opening timing of the rotary valve 50 approaches the valve opening timing of the intake valve 19, so that the generated impulse is also It becomes weaker, pumping loss on the high speed side can be reduced, and fuel consumption can be improved. Further, since the generated impulse is weakened, the inertial supercharging in the branch intake pipes 43A to 43D is relatively increased, and the volumetric efficiency in the cylinder can be kept high.

  In the present embodiment, the pulse generator is a rotary valve 50 that is housed in the surge tank 42 and rotates in synchronization with the crankshaft 3 of the engine 10. For this reason, in the present embodiment, it is possible to generate an impulse in the cylinder at a desired timing by reliably tuning the frequency without receiving a large intake resistance. It becomes possible to equip the rotary valve 50 which produces | generates an impulse, without inhibiting the inertia supercharging by providing the surge tank 42 or the volume tube 61. FIG.

  In the present embodiment, the diameter of the rotary valve 50 is set larger than the cross-sectional width of the branch intake pipes 43A to 43D, and the upstream ends of the branch intake pipes 43A to 43D are formed on the circumferential surface of the rotary valve 50. The openings 52 and 53 are arranged so as to be selectively opened and closed, and from the downstream end of the intake port 17 to the openings 52 and 53 of the rotary valve 50 for a single stroke volume of each cylinder 12A to 12D. The ratio of the single independent intake passage volume is set in the range of 70% to 130%. For this reason, in this embodiment, the branch intake pipes 43A to 43D can be opened and closed at a high peripheral speed, and a strong impulse can be generated. Further, the rotary valve 50 has a ratio of a single independent intake passage volume from the downstream end of the intake port 17 to the opening of the rotary valve 50 to a single stroke volume of each cylinder 12A to 12D from 70% to 130%. It is set to a position that falls within the range. This set range is a range found by simulation by the present inventors as a result of diligent research, and is a range in which the volumetric efficiency at 3500 rpm can be improved to about 90% or more as described later.

  The ratio of the single intake passage volume from the downstream end of the intake port 17 to the opening of the rotary valve 50 with respect to the single stroke volume of each cylinder 12A to 12D, that is, the intake passage / stroke volume ratio exceeds 130% However, volumetric efficiency is not necessarily reduced. However, in that case, since the intake passage becomes longer, the response to the torque improvement tends to decrease. Therefore, even if the torque during steady running can be increased, the torque may not necessarily be improved in a transient state during acceleration. On the other hand, when the intake passage / stroke volume ratio falls below 70%, the air amount necessary for the cylinder cannot be secured, so that the response is increased, but the volume efficiency is lowered. Therefore, in this embodiment, the intake passage / stroke volume ratio is set from 70% to 130%. As a result, not only the torque at the steady state but also the torque in the transient state at the time of acceleration can be efficiently increased.

  In this regard, the relationship between the stroke volume and the intake passage volume will be described.

  The present inventor performed a simulation on the relationship between the stroke volume of the cylinder and the volume of the branch pipe in the cylinder of the specification shown in Table 2 when configuring the intake device 40 of the above-described embodiment.

  In Table 2, the intake passage length is the sum of the passage lengths of the intake port 17 and the branch pipes (branch intake pipes 43A to 43D). Specifically, the intake port 17 has an open end (downstream end) with respect to the combustion chamber 5. ) To the opening 52 (53) of the rotary valve 50 (see FIG. 2). The stroke volume Vh is the volume from the piston top dead center to the piston bottom dead center of the cylinder 14, and the intake passage volume V is the volume of the intake port 17 formed in the cylinder head 12 and the branch pipe (branch intake pipes 43A to 43A). 43D).

  FIG. 11 is a graph showing the relationship between the volumetric efficiency ηv and the rotational speed N in this specification.

  The measurement results in FIG. 11 are based on the case where the intake passage length is 250 mm (in the case of T3), and the opening / closing range of the intake valve 19 when the rotary valve 50 is opened at 115 ° CA is from 50 ° CA / 30 ° CA. The maximum value at 10 ° CA / 70 ° CA is shown.

  As shown in the figure, when the intake passage / stroke volume ratio is low and the intake passage / stroke volume ratio falls below 70%, the overall volume efficiency ηv decreases as shown by T1 in the figure, particularly 3500 rpm. The volumetric efficiency ηv is greatly reduced. This is because the intake passage volume V is too small, so that a sufficient amount of air cannot be secured even by the pulse generation action by the rotary valve, and the low speed operation region (range 2500 rpm) R1 and the high speed operation region ( 4500 rpm to 5500 rpm) It is considered that R3 becomes peaky and a valley is formed at 3500 rpm. On the other hand, when the intake passage length is longer than the base length (when the intake passage / stroke volume ratio is 96% or more), the peak efficiency in the high-speed operation region R3 is alleviated, resulting in volumetric efficiency in the low-speed operation region R1. It was found that the valley at 3500 rpm tends to decrease even when ηv increases. However, if the intake passage length is increased, the response of intake air is also deteriorated, so that the transient torque during acceleration may be reduced. From these viewpoints, when the intake passage / stroke volume ratio is 70% or more and 130% or less (the intake passage length is 500 mm or less), a high torque can be obtained both in the steady state and in the transient state. It was found that the response was improved.

  Further, in the present embodiment, the intake passage length Lf is set to a length that allows inertia supercharging in the high speed operation region R3, and the intake passage length Ls is a length that allows inertia supercharging in the medium speed operation region R2. Is set. For this reason, in this embodiment, since the intake passage lengths Lf and Ls can be set short, the intake system can be made compact.

  Thus, according to this embodiment, since a suitable supercharging effect can be obtained in all the driving regions R1 to R3, the fuel efficiency and the output can be balanced according to the driving regions R1 to R3. There is an effect.

  The above-described embodiments are merely preferred specific examples of the present invention, and the present invention is not limited to the above-described embodiments.

  It goes without saying that various modifications are possible within the scope of the claims of the present invention.

1 is a right side view of a four-cycle spark ignition multi-cylinder engine according to an embodiment of the present invention. It is AA cross-section schematic of FIG. It is a perspective view which simplifies and shows the principal part of this embodiment. It is sectional drawing to which the principal part of FIG. 2 was expanded. It is the elements on larger scale which expand and show the principal part of FIG. It is a block diagram concerning this embodiment. It is a graph which shows the torque with respect to an engine speed, the phase of a rotary valve, and the opening / closing operation | movement of a VIS valve. It is a graph which shows the relationship between a torque and a fuel consumption. It is a flowchart concerning this embodiment. It is a flowchart concerning this embodiment. It is the graph which showed the relationship between volumetric efficiency and rotation speed by this specification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 12A-12D Cylinder 15 Combustion chamber 16 Spark plug 17 Intake port 19 Intake valve 21 Fuel injection valve 40 Intake device 41 Intake manifold 42 Surge tank (collection part)
43A to 43D Branch intake pipe 50 Rotary valve (PGV: Pulse generator)
52 Opening 53 Opening 56 Rotary valve advance mechanism (variable valve opening mechanism)
57 OCV system (variable valve opening mechanism)
58 PGV angle sensor 61 Volumetric tube (volume part)
63 VIS valve (volume part opening and closing mechanism)
65 Valve actuator (volume part opening / closing mechanism)
66 Engine crank angle sensor 68 Accelerator opening sensor 69 O ₂ sensor Lf Intake passage length Ls Intake passage length N Engine rotation speed Nf First predetermined rotation speed Ns Second predetermined rotation speed PH11 to PH14 Intake passage R1 Low speed operation region R2 Medium speed operation area R3 High speed operation area θ Opening angle

Claims (8)

An intake pipe that supplies air to each intake port of a plurality of cylinders, and a collecting portion that opens at the upstream end of each intake pipe,
In a control apparatus for a multi-cylinder engine that includes a pulse generator that generates a pressure wave in a cylinder by opening the valve in the middle of the intake stroke during the valve opening period of the intake port corresponding to the intake stroke of each cylinder.
Engine speed detecting means for detecting the engine speed;
A volume communicating with the intake pipe;
A volume opening and closing mechanism for opening and closing a communicating portion between the volume and the intake pipe;
Control means for controlling the operation of the pulse generator and the opening / closing operation of the volume opening / closing mechanism based on the detection of the engine speed detection means,
The intake passage length from the intake port downstream end of each intake pipe to the volume portion is set to a length that can be dynamically supercharged in a high-speed operation region equal to or higher than the first predetermined rotation speed,
The length of the intake passage from the downstream end of the intake port of each intake pipe to the collecting portion is a length that allows dynamic supercharging in a medium speed operation region that is less than the first predetermined rotational speed and is equal to or higher than a second predetermined rotational speed. Set,
The control means controls the volume portion opening / closing mechanism so as to open the volume portion at the first predetermined rotation speed or more, and operates the pulse generator in an operation region that does not satisfy the second predetermined rotation speed. A control device for a multi-cylinder engine, The control apparatus for a multi-cylinder engine according to claim 1,
The control device for a multi-cylinder engine, wherein the control means stops the operation of the pulse generator at least in an operation region from a second predetermined rotation speed to a first predetermined rotation speed. The control apparatus for a multi-cylinder engine according to claim 2,
The control unit for a multi-cylinder engine, wherein the volume part is configured by a communication path that communicates each intake pipe. The control apparatus for a multi-cylinder engine according to claim 3,
An engine load detecting means for detecting an engine load and inputting the engine load to the control means is provided, and the control means opens the volume portion even at a second predetermined rotation speed or less in the partial load region. Engine control device. The multi-cylinder engine control device according to any one of claims 1 to 4,
The pulse generator has a variable valve opening mechanism capable of changing a valve opening timing, and the control means advances the valve opening timing of the pulse generator as the engine speed approaches a second predetermined speed. A control device for a multi-cylinder engine, which controls a variable valve opening mechanism so as to make it turn. The multi-cylinder engine control device according to any one of claims 1 to 5,
The control device for a multi-cylinder engine, wherein the pulse generator is a rotary valve that is housed in the collecting portion and rotates in synchronization with a crankshaft of the engine. The multi-cylinder engine control device according to any one of claims 1 to 6,
The pulse generator is a rotary valve that rotates in synchronization with the crankshaft. The diameter of the rotary valve is set to be larger than the cross-sectional width of the intake pipe, and the upstream end of each intake pipe is located on the circumferential surface of the rotary valve. The ratio of the single independent intake passage volume from the downstream end of the intake port to the opening of the rotary valve with respect to the single stroke volume of each cylinder, arranged to be selectively opened and closed facing the formed opening Is set in the range of 70 percent to 130 percent. The control apparatus for a multi-cylinder engine according to any one of claims 1 to 7,
The intake passage length from the intake port downstream end of each intake pipe to the volume portion is set to a length that allows inertia supercharging in the high-speed operation region, and from the intake port downstream end of each intake pipe to the collecting portion. The multi-cylinder engine control apparatus is characterized in that the intake passage length is set to a length that allows inertia supercharging in the medium speed operation region.

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