JP4645252B2 - 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 quickly perform the ON / OFF operation of the pulse generator to balance the suppression of the pumping loss and the securing of sufficient volume efficiency.

  However, in any of the above-described pulse generators, it is necessary to open and close the on-off valve against the intake pressure, and thus required responsiveness cannot be obtained.

  The present invention has been made in view of the above-described problems, and is a multi-cylinder capable of switching ON / OFF operation of a pulse generator with high responsiveness and thereby balancing fuel consumption and output in accordance with the operation region. It is an object to provide an engine control device.

In order to solve the above-mentioned problems, the present invention provides a branch intake pipe that supplies air to each intake port of a plurality of cylinders, a collecting portion that opens at the upstream end of each branch intake pipe, and an intake stroke of each cylinder. Correspondingly, the engine speed is detected in a multi-cylinder engine control device equipped with a pulse generator that opens a valve during the intake stroke during the valve opening period of the intake port and generates a pressure wave in the cylinder. Engine rotational speed detecting means, engine load detecting means for detecting a load state of the engine, a plurality of EGR gas passages for recirculating the burned gas from the exhaust passage of the engine to the branch intake pipes, the EGR gas passages and the engine a recirculation passage connecting the exhaust passage and an EGR system including the engine rotational speed detecting means, and the operation and EGR pulse generator based on the detection of the engine load detecting means And control means for controlling the stem is provided, wherein, in advance pulse generator engine revolution speed set to actuate the, in the full load region, to disconnect the recirculation passage and each of EGR gas passage, In the partial load region, the control device for a multi-cylinder engine is characterized in that each EGR gas passage is connected to a recirculation passage to supply EGR gas to the branch intake pipe. In this aspect, when the engine load state is full load at an engine speed (mainly a low / medium speed rotation region) set in advance to operate the pulse generator, the control means is connected to each EGR gas passage and the reflux. Since the passage is cut off, the pressure wave generated by the pulse generator propagates into the cylinder, which promotes fuel vaporization in the cylinder, improves volumetric efficiency, and provides high torque. become. On the other hand, in the partial load range, the pressure wave control means Runode refluxed passageway communicating the EGR gas passage, the pulse generator has generated is attenuated by propagating in the intake pipe through the EGR gas passage. For this reason, since the operation of the pulse generator is substantially stopped, the pumping loss due to the pressure wave of the pulse generator can be rapidly reduced and the fuel consumption can be improved.

In a preferred embodiment, as a means to communicate blocking or communicating a pre-SL and the EGR gas passage and the return passage, a single EGR valve for opening and closing the upstream side of the EGR gas passage is provided. In this aspect, each branch passage functions as a closed tube having a small volume, and pulsation between cylinders can be suppressed.

In a preferred aspect, the EGR valve blocks communication with a cylinder having an adjacent combustion order when the EGR gas passage is closed. In this aspect, when the EGR gas passage is closed by the EGR valve, the cylinder in the intake stroke does not communicate with the opened cylinder. Therefore, in the operation region where the pulse generator is to function, the generated pressure wave is not attenuated by communicating with the cylinder in which the cylinder in the intake stroke is opened. Therefore, when the EGR gas passage is closed, it is possible to reliably improve the volume efficiency by the pulse generator.

In a preferred aspect, the pulse generator is a rotary valve that rotates in the collecting portion in synchronization with the crankshaft, and the EGR gas passage is configured on the downstream side of the collecting portion. 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 is possible to equip a pulse generator that generates a pressure wave without hindering dynamic supercharging by providing a collecting portion.

As described above, according to the present invention, since the ON / OFF operation of the pulse generator can be switched with high responsiveness by the opening and closing operation of the EGR gas passage , the fuel consumption and the output are balanced according to the operation region. It is possible to provide a remarkable effect of providing a control device for a multi-cylinder engine.

First, a reference form serving as a basis of the embodiment of the present invention will be described.

1 is a right side view of a four-cycle spark-ignition multi-cylinder engine according to a reference embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view taken along the line AA of FIG. FIG. 3 is a perspective view schematically showing the 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 has an intake manifold 41 fixed to the side 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 this reference 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 reference form , each of the branch intake pipes 43A to 43D has passage lengths of the intake passages PH11 to PH14 (in this reference form , 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 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 reference form , 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 rotational speed of the engine, 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 reference form , 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 of the branch intake pipes 43 </ b> A to 43 </ b> D is provided with a VIS (Variable Induction System) 60 as a variable passage length system.

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 reference form, 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 reference form , 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.

Referring to FIG. 2, the engine 10 is provided with a pair of engine crank angle sensors 66 as engine speed detection means. Each engine crank angle sensor 66 is disposed around the crankshaft 3 with a predetermined phase difference, and detects the rotational speed of the engine 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. An O ₂ sensor 69 for detecting the amount of oxygen is provided.

  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. Accordingly, 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 the inertia supercharge is generated is R2, and the intake passage length is Lf, and the high speed in which the inertia supercharge is generated. 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 reference embodiment described above 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 reference form , the phase of the rotary valve 50 at the time of engine start 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, when the engine operating state is the full load state at step S5, or when the engine speed N is less than the first predetermined speed Nf at step S10, the ECU 100 has a flag F value of 1. (Step S11), if 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 , the communication path is configured by the VIS 60 as a variable intake path length system that changes the intake path length from the collecting portion to the intake port. For this reason, in this reference embodiment , the dynamic supercharging by the ON / OFF operation of the rotary valve 50 and the change of the intake passage lengths Lf and Ls is performed by changing the intake passage lengths Lf and Ls according to the rotation region of the engine 10. It becomes possible to balance fuel efficiency and output by combining effects.

Particularly 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. It is possible to cause inertia supercharging between the downstream end of the intake port 17 in the 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 this reference 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 use the inertia supercharging of the intake passage due to the provision of the volume pipe 61 or the surge tank 42. .

Moreover, in this reference form , the said volume pipe | tube 61 is comprised by the communicating path which connects each branch intake pipe 43A-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. Therefore, 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 the engine load and inputting it to the ECU 100. In the partial load region, the ECU 100 has a volume even at a second predetermined rotational speed Ns or less. The tube 61 is opened. For this reason, in the present embodiment , high volume efficiency can be obtained by the supercharging effect by the rotary valve 50 in the fully open operation region where the engine 10 is heavily loaded, while in the other partial load regions, the volume pipe 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 reference 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. Therefore, in this reference 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 peripheral 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 reference 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 the present 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 having the specifications shown in Table 2 when configuring the intake device 40 of the reference embodiment described above.

  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, if 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 , the intake passage lengths Lf and Ls can be set short, so that the intake system can be made compact.

Next, another reference embodiment employing the VIS 60 will be described with reference to FIG.

Figure 12 is a graph showing the relationship between another according to a reference embodiment torque and the engine speed N of the present invention, the graph 13 showing the relationship between the rotary valve and VIS valve and the torque in the low-speed operation range of the engine 10 It is.

With reference to each figure, in this reference form , the temperature of the cooling water detected by the engine water temperature sensor 67 is adopted as the temperature related to the in-cylinder temperature of the engine 10, and the detected temperature of the engine water temperature sensor 67 is preset. When the engine 10 is cold when the temperature is lower than the predetermined temperature Wt1, the high temperature above the predetermined temperature Wt1 is determined as the warm time, and the operation region of the rotary valve 50 during the cold time (the PGV operation region when cold) It is determined in ECU 100 that R4 is wider than the operating region (warm PGV operation region) R5 of rotary valve 50 when warm. That is, as apparent from FIG. 12, when the engine 10 is warm, the operating region R5 of the rotary valve 50 is set up until the engine speed N is about 1500 rpm, whereas when the engine 10 is cold, The operating region R4 of the rotary valve 50 is expanded according to the engine load state until the engine speed N is about 2500 rpm. Accordingly, in the operation of the VIS valve 63, the timing at which the volume tube 61 is opened on the low load side is expanded to the high load side in the cold time torque τ2 than in the warm time torque τ1.

Next, as a means for determining the activation state of the catalyst, in this embodiment , the detected temperature Wt of the engine water temperature sensor 67 is adopted as the temperature related to the activation temperature of the exhaust gas purification catalyst, and this detected temperature Wt is preset. The ECU 100 is configured to discriminate a low temperature that is less than the predetermined temperature (a temperature corresponding to the catalyst active state) as an inactive state of the catalyst and a high temperature that is higher than the predetermined temperature as an active temperature state. Note that the activation state of the exhaust gas purification catalyst may be determined using both the water temperature detection and the determination of the elapsed time from the start of the engine, or the catalyst temperature may be directly detected.

In the present embodiment , as shown in FIG. 12, since the region R5 is defined even during the warm period and the rotary valve 50 is operated in this operation region, the vaporization mist of the fuel is separated from the improvement of the torque. It is possible to effectively use the rotary valve 50 in order to promote the conversion and improve the combustion stability.

Further, as is clear from FIG. 13, in the illustrated reference form , in the low speed operation region of the engine 10, the VIS valve 63 is closed and the rotary valve 50 is operated even on the high load side (region of torque τ3 or more). Is set to As a result, in the low speed / low load area where fuel vaporization is important and in the low speed / high load area where high output performance is required, the rotary valve 50 operates to improve combustion stability and volume efficiency. On the other hand, in the low-speed / medium-load region where there is relatively little demand, the output is secured while improving fuel efficiency by the dynamic supercharging effect of the branch intake pipes 43A to 43D due to the opening of the VIS valve 63. Is configured to do.

  FIG. 14 is a graph showing the relationship between the in-cylinder pressure and the crank angle, where (A) is a cold time and (B) is a warm time. In FIG. 14, IN indicates the valve opening characteristics of the intake valve 19, and C11 and C12 indicate the valve opening characteristics of the rotary valve 50 when cold and warm, respectively.

Referring to FIGS. 6A and 6B, in the illustrated reference embodiment , fuel injection timings Tr1 and Tr2 are individually set when the engine 10 is cold and warm.

In this reference embodiment , when cold, fuel is injected in the first half of the intake stroke before the rotary valve 50 is opened, and when warm, fuel is injected near the opening timing of the rotary valve 50 (preferably immediately after the valve is opened). It is set to spray.

Next, an operation flow according to the reference embodiment in which the settings of FIGS. 15 to 17 are flowcharts based on the settings of FIGS. 12 to 14.

Referring to FIG. 15, in the above configuration, after setting the target value of rotary valve 50 after the engine is started (steps S <b> 101 to S <b> 103) as in the reference embodiment shown in FIG. It is determined whether or not it is a low load region (step S104).

  Referring to FIG. 16, when the operating region of engine 10 is the low rotation / low load region, ECU 100 determines the exhaust gas purification catalyst (not shown) based on the detected value of engine water temperature sensor 67 as the catalyst active state detecting means. The active state is determined (step S105). If it is determined that the active state is good, the ECU 100 determines whether or not the detected temperature Wt of the engine water temperature sensor 67 is less than the predetermined temperature Wt1, that is, whether or not the engine 10 is cold ( Step S106). If the engine 10 is cold, the ECU 100 changes the retardation correction region of the rotary valve 50 corresponding to the detected temperature Wt (step S107), and further, the ECU 100 changes the retardation valve 50 corresponding to the detected temperature Wt. The set value is changed (step S108). These steps S107 and S108 are realized by storing data collected beforehand through experiments or the like in the ECU 100 as a control map and based on the control map.

  Further, ECU 100 sets the fuel injection timing from the control map based on the graph shown in FIG. 14 (step S109). In this flow, since it is cold, the ECU 100 sets the injection timing to the cold fuel injection timing Tr1 based on FIG. Further, the ignition timing is retarded corresponding to the setting in steps S109 and S110.

  Thereafter, the ECU 100 drives the rotary valve 50 based on the settings in steps S107 and S108 described above (step S110). Thereafter, fuel is injected based on the setting in step S109 (step S111). In this flow, since the fuel is injected at the cold fuel injection timing Tr1 shown in FIG. 14A in the cold state, the impulse generated by the rotary valve 50 at the cold time when the combustion stability is low, Fuel vaporization and atomization are promoted. Thereby, combustion stability improves and exhaust performance also becomes high.

  Then, after the fuel is injected, sparks are ignited at a predetermined time, whereby the air-fuel mixture whose mixing is promoted by the rotary valve 50 is burned, and torque is generated (step S112).

  After the spark ignition is executed, the ECU 100 returns to step S102 until the engine 10 stops (step S113).

  Next, when it is determined in step S105 that the activation of the exhaust gas purification catalyst is insufficient, the ECU 100 sets the set value of the rotary valve 50 to the most retarded amount (step S114).

  Next, in order to improve the exhaust performance, the ECU 100 sets the air-fuel ratio to the stoichiometric air-fuel ratio (step S115). Thereafter, ECU 100 sets the fuel injection mode to a split fuel injection mode that is divided into two so as to create more exhaust energy (step S116). Thereafter, the ignition timing is set to a value retarded by a predetermined amount from the compression top dead center (step S117), and thereafter, the process proceeds to step S110 and subsequent steps.

  As a result, when step S110 is executed, the rotary valve 50 opens in the state most delayed from the intake valve 19, so the cylinder 12A in the intake stroke until the rotary valve 50 is opened. A large negative pressure will be generated within ~ 12D.

  Further, when step S111 is executed based on step S116, the fuel set at the stoichiometric air-fuel ratio is divided into two parts and injected within the intake stroke.

  When step S112 is executed based on step S117, the spark plug 16 ignites the air-fuel mixture with the ignition timing retarded by a considerable amount. As a result, a relatively large amount of exhaust energy is generated, and the temperature of the exhaust gas purification catalyst quickly rises, so that the exhaust gas purification catalyst is activated.

  Next, in step S106, after the exhaust gas purification catalyst is activated, when the in-cylinder temperature also reaches the warm region, the ECU 100 determines that the engine speed N is in the idling speed region (region below the idling speed). Is determined (step S118). If the engine speed N is in the idling speed range, the ECU 100 sets the operating condition of the rotary valve 50 to the set value at the time of warm in FIGS. 12 and 13 (step S119). After completing this step S119, the ECU 100 proceeds to step S109.

  Since this flow is warm, the ECU 100 sets the injection timing to the warm fuel injection timing Tr2 in FIG. The ignition timing is advanced to the vicinity of the compression top dead center.

  Next, when the control proceeds to the subsequent step, the rotary valve 50 operates under the warm operating conditions (step S110), and fuel is injected immediately after the opening timing of the rotary valve 50 (step S111), and a spark is generated. It is ignited (step S112). For this reason, fuel is injected immediately before the impulse is generated, and the fuel gets on the intake air and is pushed into the cylinders 12A to 12D. As a result, the fuel is also efficiently introduced into the cylinders 12A to 12D and mixed with the fresh air, so that mixing is promoted and the fresh air is cooled by the latent heat of vaporization of the fuel. Therefore, even when the air-fuel ratio is enriched in a high load state, it is possible to suppress the fuel from adhering to the passage wall surface and enhance the function of preventing knocking due to vaporization latent heat.

  On the other hand, if the engine speed N exceeds the idle speed range in step S118, the control shifts to step S121 of the flow described below.

  Referring to FIG. 17, in the determination of step S104 in FIG. 15, when the engine operation region is other than the low speed and low load region, ECU 100 determines whether or not the operation region of engine 10 is the partial load region. (Step S120). If it is the partial load region, the ECU 100 refers to the flag F of the VIS valve 63 (step S121). If the value of the flag F is 0, the ECU 100 opens the VIS valve 63 (step S122). After updating the value to 1 (step S123), the process proceeds to step S109. If the value of the flag F is 1 in step S121, the process proceeds to the next step S109.

  On the other hand, when the engine operating state is the full load state in step S120, the ECU 100 refers to whether or not the value of the flag F is 1 (step S124), and if the value of the flag F is 1 The VIS valve 63 is closed (step S125), the value of the flag F is updated to 0 (step S126), and the process proceeds to step S109. If the value of the flag F is 0, the process proceeds to step S109 as it is.

In the present embodiment , when the engine 10 is traveling at a low speed and the load region is the medium load region R12, the operation of the rotary valve 50 is stopped. As a result, in the low speed / medium load region R12, the pumping loss due to the rotary valve 50 can be avoided, and the fuel consumption in this region can be improved. On the other hand, in the low speed / low load region R11, a particularly large negative pressure is generated in the intake passage due to the generation of the impulse by the rotary valve 50. As a result, fuel vaporization is improved, fuel and air mixing properties and exhaust performance associated therewith are improved, and combustion stability can be improved. Furthermore, in the low speed / high load region R13, high volumetric efficiency can be maintained by the generation of impulses by the rotary valve 50, so that the output performance can be improved.

In this reference embodiment , an engine water temperature sensor 67 is provided as a catalyst activation state detection means, and the ECU 100 operates the rotary valve 50 in all operating load regions when the detected catalyst is not activated. Is. In the case where the exhaust gas purification catalyst has not yet been sufficiently activated since the engine 10 has started, the exhaust performance is prioritized over the fuel efficiency. For this reason, in this reference embodiment , in such an operation region, the rotary valve 50 operates to generate an impulse and to be supercharged regardless of the load state. As a result, in the operating region where the catalyst is not sufficiently activated, a large negative pressure is generated in the cylinder, fuel vaporization and atomization are promoted, combustion stability is improved, and exhaust performance is also improved.

In the present embodiment , an engine water temperature sensor 67 is provided as an in-cylinder temperature detecting means for detecting a temperature related to the in-cylinder temperature of the engine 10, and the ECU 100 detects that the engine temperature is cold when the detected temperature Wt is less than the predetermined temperature Wt1. The rotary valve 50 is operated in ten low speed operation regions R1. For this reason, in the present embodiment , the fuel vaporization is improved by the impulse generated by the rotary valve 50 when the engine 10 is cold and the combustion stability is deteriorated. For this reason, the combustion stability when the engine 10 is cold increases.

In the present embodiment , the ECU 100 delays the opening timing of the rotary valve 50 as the detected temperature Wt of the engine 10 is lower, as described in the flowchart of FIG. Therefore, in the present embodiment , when the engine 10 that needs to improve the combustion stability is cold, the lower the detected temperature Wt, the larger the negative pressure is generated, and the in-cylinder vaporization can be improved. . Therefore, fuel vaporization and atomization can be promoted, and combustion stability can be improved.

In the present embodiment , as shown in the graph of FIG. 12, the ECU 100 controls the drive of the rotary valve 50 when the engine 10 is cold in the operating region at a higher speed than when the engine 10 is warm. For this reason, in this reference embodiment , when the engine 10 having poor combustion stability is cold, the rotary valve 50 generates an impulse until the engine 10 reaches a relatively high speed operation region. , Atomization is promoted in a wide operating region, and combustion stability is improved.

In the present embodiment , the ECU 100 operates the rotary valve 50 when the detected temperature Wt is a predetermined temperature Wt1 or higher and the engine speed N is in the idle speed range. For this reason, in the present embodiment , the intake valve speed can be increased by generating the impulse by the rotary valve 50 during the warm idle operation in which the exhaust performance needs to be improved. As a result, the fuel is pushed into the cylinder by the intake air having a high flow velocity, and it becomes possible to promote fuel vaporization, atomization, and mixing characteristics with air.

In the present embodiment , as shown in FIGS. 14A and 14B, when the engine 10 is cold, the ECU 100 injects fuel in the first half of the intake stroke before the rotary valve 50 is opened. In the warm state, the fuel injection valve 21 is controlled so that fuel is injected near the opening timing of the rotary valve 50. For this reason, in the present embodiment , in the cold time when it is necessary to improve the vaporization, the fuel is injected at the timing when the in-cylinder pressure is high, that is, the first half of the intake stroke before the rotary valve 50 is opened. This makes it possible to promote fuel vaporization and atomization. In addition, since the fuel is injected in the vicinity of the opening of the rotary valve 50 during the warm period, the fuel is injected immediately before the impulse is generated, and this fuel gets on the intake air and is pushed into the cylinder. It will be in a state to be turned. As a result, the fuel is also efficiently introduced into the cylinder and mixed with the fresh air, so that mixing is promoted and the fresh air is cooled by the latent heat of vaporization of the fuel. Therefore, even when the air-fuel ratio is enriched in a high load state, it is possible to suppress the fuel from adhering to the passage wall surface and enhance the function of preventing knocking due to vaporization latent heat. Thus, in this reference embodiment , it is possible to perform suitable fuel injection control according to the temperature state of the engine 10.

In the present embodiment , as shown in FIG. 13, the ECU 100 advances the rotary valve so that the valve opening timing of the rotary valve 50 is advanced in the low load region as the engine load approaches the threshold value in the medium load region. The corner mechanism 56 is controlled. For this reason, in this embodiment , the valve opening timing of the rotary valve 50 approaches the valve opening timing of the intake valve 19 as the engine load approaches the threshold (torque τ1 or torque τ2) in the middle load region. Impulse is also weakened, and in the low load region, the pumping loss on the high load side can be reduced and the fuel consumption can be improved.

In the present embodiment , as shown in FIG. 13, the ECU 100 performs a rotary valve advance mechanism in the high load region so as to retard the valve opening timing of the rotary valve 50 as the engine load approaches the full load region. 56 is controlled. For this reason, in this reference embodiment , the opening timing of the rotary valve 50 moves away from the opening timing of the intake valve 19 as the operating region shifts to the high engine load side that requires a larger output, so that the generated impulse is also reduced. The output can be increased on the high load side in the high load region.

Further, in the present embodiment , the volume pipe 61 of the VIS 60 is provided on the downstream side of the rotary valve 50 and constitutes a communication path that communicates with the branch intake pipes 43A to 43D. A VIS valve 63 is provided as an opening / closing mechanism for opening and closing the tube 61. For this reason, in this reference embodiment , when the ECU 100 turns the rotary valve 50 on / off, the impulse generated by the rotary valve 50 is attenuated by opening the VIS valve 63 of the volume tube 61 while the rotary valve 50 itself is in operation. Thus, the function can be substantially stopped.

  Further, various changes can be made to the above-described communication path.

Next, an embodiment of the present invention will be described on the basis of each of the above reference embodiments. Figure 18 is an enlarged fragmentary cross-sectional view according to implementation embodiments of the present invention.

With reference to the figure, in the illustrated embodiment, an EGR system 70 is provided . The EGR system 70 includes EGR gas passages 71A to 71D connected to the branch intake pipes 43A to 43D of the first cylinder (# 1) to the fourth cylinder (# 4), and upstream of the EGR gas passages 71A to 71D. an EGR valve 72 which is connected to a section, that has a return passage 73 connecting the exhaust passage 35 of the engine 10 in the EGR valve 72.

  FIG. 19 is a partially broken perspective view showing a specific configuration of the EGR valve 72 according to the embodiment of FIG. 18, and FIG. 20 is a partially enlarged sectional view showing the operation of the EGR valve 72. FIG. 21 is a view on arrow AA in FIG. 20.

  With reference to the drawings, the EGR valve 72 has a substantially rectangular casing 701. The casing 701 is a metal product having a hollow inside, and an introduction chamber 702 to which the reflux passage 73 is connected and the EGR gas passages 71A to 71D are connected to a lower portion thereof by a pair of partition plates 701a and 701b. A discharge chamber 703 and a storage chamber 705 for storing a part of the valve operating mechanism 704 are partitioned.

  This valve operating mechanism 704 is provided at a solenoid actuator (not shown) fed from the connector 704a, a rod 704b extending up to the introduction chamber 702 while being driven up and down by the solenoid actuator, and a lower end of the rod 704b. An open / close valve 707 that opens and closes the communication portion 706 formed in the partition plate 701a that partitions the introduction chamber 702 and the discharge chamber 703, and a spring (not shown) that biases the rod 704b in the direction in which the open / close valve 707 closes the communication portion 706. have. Therefore, in a state where the solenoid is demagnetized, the on / off valve 707 closes the communication portion 706 and restricts the EGR gas from the recirculation passage 73 from being introduced into the EGR gas passages 71A to 71D by the biasing force of the spring. To do. On the other hand, in a state where the solenoid is excited, the rod 704b is pushed down against the biasing force of the spring, the on-off valve 707 opens the communication portion 706, and EGR gas is introduced from the reflux passage 73 into the EGR gas passages 71A to 71D. It is the structure which accepts.

  In the illustrated embodiment, the communication portion 706 is embodied by an annular seal ring 706a fitted in the center of the partition plate 701a, and the on-off valve 707 has a columnar shape introduced into the seal ring 706a. It integrally has a portion 707a and a seal portion 707b formed at the lower end of the columnar portion 707a and joined to the lower surface of the seal ring 706a, and as shown in FIG. It is configured as follows.

  Further, a guide sleeve 708 for guiding the rod 704 b is fixed to the partition plate 701 b that partitions the storage chamber 705 and the discharge chamber 703, and extends over the discharge chamber 703. A rectangular partition plate 709 that equally divides the discharge chamber 703 into four equal parts is fixed to the guide sleeve 708 in a state of being equally distributed in the circumferential direction. The EGR gas passages 71 </ b> A to 71 </ b> D are connected to communicate with each space partitioned by the partition plate 709. Therefore, as is apparent from FIGS. 20A and 20B, when the on-off valve 707 opens the communication portion 706, the inside of the space divided into four in the discharge chamber 703 via the communication portion 706 When the EGR gas is introduced to the EGR gas passages 71A to 71D and the on-off valve 707 closes the communication portion 706, the columnar portion 707a of the on-off valve 707 is placed in the seal ring 706a. As a result of closing the communication portion 706 in the state of being introduced into the space, the space divided into four equal parts in the discharge chamber 703 is individually sealed. For this reason, each EGR gas passage 71A-71D functions as a closed tube with a small volume in a state where they are blocked from each other.

  FIG. 22 is a graph showing the relationship between torque and engine speed when the EGR system shown in FIGS. 18 to 21 is used.

  Referring to FIG. 18, when using the EGR system shown in FIGS. 18 to 21, ECU 100 has a PGV operation region R6 in which rotary valve 50 operates and an EGR introduction region R7 in which EGR system 70 is operated. Is set. The PGV operation region R6 is set to a range indicated by the oblique lines in FIG. With this setting, in the region where the engine speed N is less than the predetermined medium speed Ns, the operation of the rotary valve 50 is stopped on the low load side where the engine load is less than the predetermined torque τ1, thereby improving fuel efficiency. Or operation in a region where pulse generation is difficult can be stopped. On the other hand, on the high load side where the engine load is equal to or greater than the predetermined torque τ1, an impulse is generated by the rotary valve 50 to improve volumetric efficiency and secure torque. Furthermore, the operation of the rotary valve 50 is stopped even in a region where it is difficult to generate a pulse with the engine speed N being equal to or higher than the medium speed Ns.

  Next, the EGR introduction region R is set within a predetermined load region in a region from a predetermined low rotational speed N1 to less than the medium rotational speed Ns. In such a low-revolution medium-load operation region, fuel efficiency and exhaust performance are prioritized over the output of the engine 10, so in this embodiment, EGR gas is introduced into the branch intake pipes 43A to 43D to substantially rotate the engine. The operation of the valve 50 is stopped.

  FIG. 23 is a flowchart according to the embodiment when the EGR system shown in FIGS. 18 to 21 is used.

  With reference to the figure, even when the EGR system shown in FIGS. 18 to 21 is used, the control flow is basically the same as the control in FIGS. 15 and 16. However, in step S104 in FIG. 15, if the engine operating region is not the low speed rotation / low load region, as shown in FIG. 23, first, the engine 10 is cooled by comparing the detected temperature Wt with the predetermined temperature Wt1. It is determined whether or not it is time (step S30). If it is cold (Wt <Wt1 is YES), the ECU 100 further determines whether or not the operation region of the engine 10 is the EGR introduction region R7 shown in FIG. 22 (step S31). If the operating region of the engine 10 is the EGR introduction region R7, the ECU 100 refers to the flag Fe for operating the EGR valve 72 (step S32). The domain of the flag Fe is alternatively set with 0 as the value for closing the EGR valve 72 and 1 as the value for opening. In step S32, when the value of the flag Fe is 0, the ECU 100 opens the EGR valve 72 (step S33). Also in this aspect, as a means for stopping the operation of the rotary valve 50, in step S33 of this embodiment, the rotary valve advance mechanism 56 is not directly controlled, but the EGR valve 72 is opened to open the EGR gas passage. Since the branch intake pipes 43A to 43D are communicated with each other via 71A to 71D, it is possible to exhibit high responsiveness compared to the case where the rotary valve 50 having a large inertia and air resistance is directly driven. become. 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 Fe to 1 (step S34). In step S32, if the value of the flag Fe is 1, the process proceeds to the next step as it is.

  On the other hand, if the engine operating state is warm in step S30, or if it is not the EGR introduction region R7 in step S31, the ECU 100 refers to whether or not the value of the flag Fe is 1 ( Step S35) If the value of the flag F is 1, the EGR valve 72 is closed (Step S36), and the value of the flag F is updated to 0 (Step S37). If the value of the flag F is 0, the process proceeds to step S110 as it is.

In the present embodiment, the ECU 100 controls the EGR valve 72 when the load state of the engine 10 is full load at an engine speed (mainly a low / medium speed rotation region) N set to operate the rotary valve 50 in advance. Since the EGR gas passages 71A to 71D and the reflux passage 73 are closed and the impulse generated by the rotary valve 50 is propagated into the cylinder, the vaporization of fuel in the cylinder is promoted and the volume efficiency is improved. It is possible to improve and obtain a high torque. On the other hand, in the partial load range, ECU 100 is Runode is communicated with the return passage 73 of the EGR gas passage 71A~71D drives the EGR valve 72, the impulse rotary valve 50 is generated through the EGR gas passage 71A~71D Then, it is attenuated by propagating to each of the branch intake pipes 43A to 43D. For this reason, since the operation of the rotary valve 50 is substantially stopped, the pumping loss due to the impulse of the rotary valve 50 can be rapidly reduced and the fuel consumption can be improved.

In particular, in the embodiment shown in FIGS. 18 to 23, an EGR system 70 that recirculates the burned gas from the exhaust passage 35 of the engine 10 under the control of the ECU 100 is provided. The ECU 100 distributes the EGR gas to the branched intake pipe 43A in the partial load region. The EGR system 70 is operated so as to be supplied to .about.43D (that is, the EGR gas passages 71A to 71D are communicated with the reflux passage 73 ). For this reason, in the present embodiment, in the EGR introduction region R7 in which fuel efficiency is prioritized over the volumetric efficiency (and hence torque) improvement by the rotary valve 50, the EGR system 70 operates and the operation of the rotary valve 50 is substantially stopped. In addition, the EGR gas can reduce pumping loss and improve exhaust performance.

In this embodiment, E GR valve 72, but also to block the communication between the cylinder combustion sequence adjacent during occlusion of E GR gas passage 71A to 71D. Therefore, in this embodiment, when E GR valve 72 closes the EGR gas passage 71A to 71D, it will not be the cylinder communicating with the cylinder is opened on the intake stroke. Therefore, in the operation region where the rotary valve 50 is to function, the generated impulse does not attenuate due to the communication between the cylinder in the intake stroke and the opened cylinder. Therefore, at the time of closure of the E GR valve 72, it is possible to achieve a reliable improvement in volumetric efficiency due to the rotary valve 50.

In particular, in the present embodiment, EGR gas passages 71A to 71D of the EGR system 70 that recirculates the burned gas from the exhaust passage 35 of the engine 10 under the control of the ECU 100 are provided, and the ECU 100 performs EGR in the partial load region. The EGR system 70 is operated so as to supply gas to the branch intake pipes 43A to 43D. For this reason, in the present embodiment, in the EGR introduction region R7 in which fuel efficiency is prioritized over the volumetric efficiency (and hence torque) improvement by the rotary valve 50, the EGR system 70 operates and the operation of the rotary valve 50 is substantially stopped. In addition, the EGR gas can reduce pumping loss and improve exhaust performance. Also, in the operating region to the functioning of the rotary valve 50 (PGV operating range R6 in FIG. 22) is, the EGR gas into the cylinder 12A~12D in the intake stroke is introduced rather than obstruction of E GR valve 72 In some cases, it is possible to reliably improve the volume efficiency by the rotary valve 50.

In the present embodiment, the EGR gas passage is composed of the EGR gas passage 71A~71D as branch passage connected to the branch intake pipes 43A to 43D, the front Symbol E GR valve 72, the EGR gas passage It is a single EGR valve 72 that opens and closes the upstream side of 71A to 71D. For this reason, in this embodiment, each EGR gas passage 71A-71D functions as a closed tube with a small volume, and it becomes possible to suppress the pulsation between cylinders.

Implementation embodiments described above are merely preferred embodiments of the present invention, the present invention is not limited to the embodiments described above. 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 a reference 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 reference form . 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 reference form . 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 which concerns on this reference form . It is a flowchart which concerns on this reference form . It is the graph which showed the relationship between volumetric efficiency and rotation speed by this specification. It is a graph which shows the relationship between the torque and engine speed which concern on another reference form of this invention. It is a graph which shows the relationship between a rotary valve and a VIS valve, and a torque in the low-speed driving | running area | region of an engine. It is a graph which shows the relationship between a cylinder pressure and a crank angle, (A) is at the time of cold, (B) is at the time of warm. It is a flowchart based on the setting of FIGS. It is a flowchart based on the setting of FIGS. It is a flowchart based on the setting of FIGS. It is an enlarged sectional view according to the implementation embodiments of the present invention. It is a partially broken perspective view which shows the specific structure of the EGR valve which concerns on embodiment of FIG. It is a partial expanded sectional view which shows the operation | movement of the same EGR valve. It is an AA arrow line view of FIG. It is a graph which shows the relationship between the torque at the time of utilizing the EGR system shown in FIGS. 18-21, and an engine speed. It is a flowchart which concerns on embodiment in the case of utilizing the EGR system shown in FIGS.

DESCRIPTION OF SYMBOLS 10 Engine 12A-12D Cylinder 14 Cylinder 17 Intake port 18 Exhaust port 19 Intake valve 20 Exhaust valve 21 Fuel injection valve 22 Camshaft 35 Exhaust passage 40 Intake device 41 Intake manifold 42 Surge tank 43A-43D Branch intake pipe 44 Throttle body 50 Rotary Valve 56 Rotary valve advance mechanism 57 OCV system 58 Angle sensor 60 VIS (an example of variable path length system)
61 Volumetric tube 63 Valve 64 Drive shaft 65 Valve actuator 66 Engine crank angle sensor 67 Engine water temperature sensor (an example of catalyst active state detection means / in-cylinder temperature detection means)
68 Accelerator opening sensor (an example of engine load detection means)
69O ₂ sensor 70 EGR system 71A to 71D EGR gas passage 72 EGR valves

Claims (4)

A branch intake pipe for supplying air to each intake port of a plurality of cylinders;
A collecting portion where the upstream end of each branch intake pipe opens,
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;
Engine load detecting means for detecting the load state of the engine;
An EGR system including a plurality of EGR gas passages for returning the burned gas from the engine exhaust passage to each branch intake pipe, and a return passage for connecting each EGR gas passage to the engine exhaust passage ;
And a control means for controlling the operation of the pulse generator and the EGR system based on the detection of the engine speed detector and the engine load detector, and the controller is set in advance to operate the pulse generator. in the engine speed is in the full load region, the isolation from the recirculation passage and the EGR gas passage, in the partial load region, supplying the branch intake pipe EGR gas each EGR gas passage is communicated return passage and communicating A control device for a multi-cylinder engine. The control apparatus for a multi-cylinder engine according to claim 1,
Control device for a multi-cylinder engine, characterized in that as a means to communicate blocking or communication between the recirculation passage and before Symbol the EGR gas passage, a single EGR valve for opening and closing the upstream side of the EGR gas passage is provided. The control apparatus for a multi-cylinder engine according to claim 2,
The control device for a multi-cylinder engine, wherein the EGR valve blocks communication with a cylinder having an adjacent combustion order when the EGR gas passage is closed. The multi-cylinder engine control device according to any one of claims 1 to 3,
The control device for a multi-cylinder engine, wherein the pulse generating device is a rotary valve that rotates in a collecting portion in synchronization with a crankshaft, and the EGR gas passage is configured downstream of the collecting portion. .

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