JP2003161189A - Intake control unit of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intake control unit which reduces pumping loss in an intake stroke and which suppresses counterflow of exhaust gas to an intake passage so as to prevent aggravation of combustion, thereby improving fuel consumption. <P>SOLUTION: In the intake control unit 4 of an internal combustion engine 1, an intake control valve 40 performs the first opening/closing operation in which it operates from a fully closed state (1) to a fully opened state (2) after the overlap period of an inlet valve, and an exhaust valve has passed in one cycle of the internal combustion engine. Then the valve operates from a fully opened state (3) to a fully closed state (4) prior to closure of the inlet valve after completion of required intake operation. The intake valve 40 performs the second opening/closing operation in which it operates from a fully closed state (5) to a fully opened state (6) again after the inlet valve has been closed, so that the pressure in the intake passage (a dead volume portion D) is made equal to the atmospheric pressure, and then it operates from a fully opened state (7) to a fully closed state (8) again prior to opening of the inlet valve. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for controlling the opening and closing of an intake control valve provided in an intake passage of an internal combustion engine so that the amount of intake air can be controlled for each cylinder. To an intake control device for an internal combustion engine. 2. Description of the Related Art Conventionally, an intake control valve is provided in an intake passage of an internal combustion engine and the opening and closing of the intake control valve is controlled so that an intake air amount can be controlled for each cylinder separately from a throttle valve provided in the internal combustion engine. 2. Description of the Related Art There is known an intake control device capable of controlling the intake air pressure. In this type of intake control device, an intake control valve provided in an intake passage of each cylinder can be independently opened and closed by an actuator. Therefore, the opening and closing timing of the intake control valve is controlled according to the rotational speed and load of the internal combustion engine. Control of the internal combustion engine to improve the output by preventing the backflow of intake air generated during the intake stroke in the low speed range of the internal combustion engine, or to reduce pumping loss at the time of partial load of the internal combustion engine, particularly at idling. It is known that fuel efficiency can be improved. Also, when the internal combustion engine is under a low load, especially when idling, air is sucked in only one port, and swirl and tample are generated in the cylinder, fuel atomization is improved, and fuel and air are mixed well. Is also known to improve combustion. Japanese Patent Laid-Open Publication No. 4-29252 discloses a conventional apparatus for controlling the opening / closing timing of an intake control valve in a low rotation range.
No. 8 is known. This device is intended to reduce the pumping loss when the internal combustion engine is partially loaded, particularly when idling, by closing the intake control valve early in the intake stroke as shown in FIG. However, in the above prior art, as shown in FIG. 9, the intake control valve is opened and closed once in synchronization with one cycle of the internal combustion engine to reduce the pumping loss. Therefore, since the intake control valve is open during the overlap OL in which the intake valve and the exhaust valve of each cylinder opened and closed by the high-speed compatible cam are open, exhaust gas flows back into the intake pipe especially at a partial load. As a result, there is a problem that combustion deteriorates and fuel consumption increases. SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to reduce the pumping loss in the intake stroke and at the same time to reduce the exhaust gas flowing into the intake passage. It is an object of the present invention to provide an intake control device for an internal combustion engine capable of preventing backflow, preventing deterioration of combustion, and improving fuel efficiency. According to the present invention, there is provided an intake control device for an internal combustion engine according to claim 1 as means for solving the above-mentioned problems. In the intake control device for an internal combustion engine according to the first aspect, the intake control valve operates from fully closed to fully open after an overlap period between the intake valve and the exhaust valve has passed during one cycle of the internal combustion engine. The first opening / closing operation in which the intake valve is fully opened and then fully closed before the intake valve is closed after the intake ends, and the fully closed and fully opened operation after the intake valve is closed and the atmospheric pressure in the intake passage Before the intake valve opens, a second opening / closing operation of operating from full opening to full closing again is performed. This allows the intake control valve to open when the exhaust valve closes after the overlap period in which both the intake and exhaust valves are open, so that backflow of exhaust gas into the intake passage can be prevented, and combustion can be prevented. Since the deterioration can be prevented, and the intake control valve is opened again after the intake valve is closed to bring the pressure in the intake passage to the atmospheric pressure and the intake stroke is started, the pumping loss can be prevented. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An intake control device for an internal combustion engine according to an embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows a system configuration of an internal combustion engine in which the intake control device of the present embodiment is mounted. As shown in FIG. 1, the system configuration of the internal combustion engine of the present invention is a four-cylinder internal combustion engine 1.
An intake system 2 and an exhaust system 3 of the internal combustion engine 1, an intake control device 4 provided in each of the intake manifolds 2a to 2d connected to each cylinder of the intake system 2, and an electronic control unit (ECU) for controlling these 5 and the like. The internal combustion engine 1 has four cylinders 1a to 1d. Each cylinder 1a to 1d is provided with an intake valve (not shown) and an exhaust valve (not shown) that are opened and closed by a high-speed compatible cam, and the intake manifolds 2a to 2d upstream of the intake valves of each cylinder are provided. , An intake control device 4 is provided. In the intake system 2 upstream of the intake manifolds 2a to 2d in which the intake control device 4 is provided, only the air cleaner 6 is provided. In the system configuration of the internal combustion engine of the present invention, opening and closing are performed by the driver's accelerator operation. No throttle valve is provided. Each cylinder 1a-1
A catalyst section 7 is provided in the exhaust system 3 downstream of the exhaust valve d. The internal combustion engine 1 has a crank angle sensor 81 which outputs a pulse signal when the piston of each of the cylinders 1a to 1d is located at the top dead center (TDC). A cylinder discriminating sensor 82 for detecting torque or combustion, an opening sensor 83 for detecting an opening of an intake control valve of the intake control device 4, an air flow meter 84 for detecting an intake air amount of the entire internal combustion engine 1, and a depression amount of an accelerator pedal. Is provided, and the detection signal from each of these sensors is E
Output to CU5. The ECU 5 is configured as an arithmetic logic circuit centering on a CPU, a ROM, and a RAM, is connected to an input / output unit via a common path, and performs input / output with the outside. A detection signal from each sensor is input to the ECU 5, and from there, a control signal is output to a rotary solenoid actuator (R / S actuator) of the intake control device 4 described later. Next, the intake control device 4 which is a feature of the present invention.
Will be described with reference to FIGS. FIG. 2 is a longitudinal sectional view of the intake control device 4. The intake control device 4 mainly includes an intake control valve 40 and an R / S actuator 50. The intake control valve 40 includes the intake manifolds 2a to 2
and d) a butterfly-shaped circular valve plate (valve element) 41 provided inside. The circular valve plate 41 is rotatably supported by a support shaft 42, and swings around the support shaft 42 in a non-contact manner while having a very narrow clearance with respect to the wall surfaces of the intake manifolds 2a to 2d. One end of the support shaft 42 is supported by the intake manifolds 2 a to 2 d by a bearing 43, and the other end of the support shaft 42 is connected to the R / S actuator 50. A spring 44 is provided at one end of the support shaft 42 for holding the circular valve plate (valve element) 41 at a neutral position (half open state) when the R / S actuator 50 is not energized. Further, the intake control valve 40 is provided with an opening sensor 83 for detecting the opening of the circular valve plate 41. The R / S actuator 50 is composed of a ferromagnetic rotor 51 and a ferromagnetic stator 52, and the rotor 51 is connected to a support shaft 42 of the intake control valve 40. FIG. 3 is a cross-sectional view of the R / S actuator 50. The rotor 51 includes a solid rod-shaped portion 5 having a circular cross section.
1a and two fan-shaped portions 51b provided symmetrically with respect to the axis of the solid rod portion 51a (the axis of the rotor) and provided on the peripheral surface of the solid rod portion 51a. Is formed. Electromagnetic coils 53a to 53d are arranged on the stator 52 in four directions at every 90 °, respectively.
A pair of protrusions 52a is formed from a portion provided with 3c toward the rotor 51 in a tapered shape.
Similarly, a pair of extending portions 52b extending from the portion where the electromagnetic coils 53b and 53d are provided and having a concave arc surface having the same shape as the arc of the sector portion 51b are formed. The one side surface of the fan-shaped portion 51b of the rotor 51 abuts the side surface of the one protruding portion 52a of the stator 52, that is, at the position shown in FIG. 3, the intake control valve 40 is fully closed. The rotor 51 is rotated so that its fan-shaped portion 51b is in contact with the arc surface of the extending portion 52b of the stator 52,
By contacting the other side of the sector 51b of the rotor 51,
The intake control valve 40 is fully opened. Accordingly, the period during which the intake control valve 40 moves from the fully closed state to the fully open state, that is,
During the period in which the rotor 51 moves from the fully closed position to the fully open position, an air gap g is formed between the side surface of the sector 51b of the rotor 51 and the protruding portion 52a of the stator 52. Changes. That is, the rotor 51 swings between the two projecting portions 52a, and swings in a range of about 90 °. FIG. 4 shows a magnetic circuit model of the R / S actuator 50. FIG.
Is a magnetic circuit model that holds the rotor 51 at the fully closed position, and (b) is a magnetic circuit model that holds the rotor 51 at the fully open position. As shown in FIG. 4A, the four electromagnetic coils 53a to 53a
When the energization direction of 53d is set, a counterclockwise closed circuit current flows in the upper left quadrant of FIG. 4A, and a counterclockwise magnetic flux is formed as shown in the figure. Similarly, FIG.
In the lower right quadrant of (a), a clockwise closed circuit current flows, and a clockwise magnetic flux is formed. No current flows in each of the lower left and upper right quadrants, and no magnetic flux is formed. Note that the magnetic resistance part corresponds to the air gap g. Therefore, in the case of a magnetic circuit as shown in FIG. 4A, a suction force acts to move the rotor 51 from the neutral position and hold the rotor 51 at the fully closed position. Next, the energizing direction of the pair of electromagnetic coils 53b and 53d is switched. Another pair of electromagnetic coils 53a,
The energizing direction of 53c is left as it is. This allows
A magnetic circuit as shown in FIG. 4B is formed. That is, a counterclockwise closed circuit current flows through the lower left quadrant of FIG. 4B, and a counterclockwise magnetic flux is formed. Similarly, a clockwise closed circuit flows through the upper right quadrant. The current of the circuit flows and a clockwise magnetic flux is formed. No current flows in each of the upper right and lower left quadrants, and no magnetic flux is formed. Therefore, in the case of a magnetic circuit as shown in FIG. 3B, an attractive force acts to move the rotor 51 from the neutral position and hold the rotor 51 at the fully open position. In this manner, the energization direction of the pair of electromagnetic coils 53b and 53d is switched to change the attraction direction, thereby changing the rotor 51 from the neutral position to the fully closed or fully open position, that is, setting the intake control valve 40 to the neutral state (half open state). To the fully closed or fully open state. FIG. 5 is a schematic diagram of the intake control device 4 of the present invention. That is, the intake control device 4 includes the intake control valve 40, R /
It comprises an S actuator 50, a spring 44 and an opening sensor 83. R / S actuator 50
Functions as a holding force forming means for keeping the intake control valve 40 fully open or fully closed, and the spring 44 returns the intake control valve 40 to the neutral position (half open state) and also improves responsiveness. ing. The opening degree sensor 83 changes the amount of current flowing through the electromagnetic coil in accordance with a signal from the opening degree sensor 83, particularly when the opening degree of the intake control valve must be kept at a small opening degree during idling. The opening of the control valve can be controlled. FIG. 6 is a graph showing the torque characteristics of the spring 44. The slope of the straight line indicates the spring constant of the spring 44. Therefore, by appropriately selecting the spring constant of the spring 44, the inclination can be increased, whereby the responsiveness of the intake control valve 40 can be improved. FIG. 7 is a graph showing the torque characteristics of the R / S actuator 50. That is, the torque characteristic when the electromagnetic coils 53a to 53d are energized as shown in FIG. 4A is shown by the lower curve, and as shown in FIG. 4B, the electromagnetic coils 53a to 53d Is shown by the upper curve. In this case, the horizontal axis is the angle of the valve body 41 or the air gap g. Generally, the attraction force obtained by energizing the coil is: attraction force = α (1 / x ² )
(Α: constant, x: air gap length). Accordingly, the suction force is inversely proportional to x ^2, as air gap length x of the air gap g is small, rapidly suction force increases. Therefore, the rotor 51 can be held at the fully closed or fully open position by a small holding current to the electromagnetic coil. Also, by controlling the current flow to the electromagnetic coil to balance the spring force and the attractive force,
The opening of the intake control valve can be adjusted. The operation of the intake control valve configured as described above will be described. When the electromagnetic coils 53a to 53d of the R / S actuator 50 are energized in the energizing direction as shown in FIG. 4A, the rotor 51 at the neutral position is rotated by the spring 44 by overcoming the torque of the spring 44, and is fully closed. Held in position. Therefore, the rotor 51
The circular valve plate 41 of the intake control valve 40, which is directly connected to the valve, is also maintained from the neutral (half open) state to the fully closed state. When the power supply to the electromagnetic coils 53a to 53d of the R / S actuator 50 is stopped, the rotor 51 and the circular valve plate 41
, And the rotor 51 reaches the vicinity of the fully opened position (the circular valve plate 41 is near the fully opened position). In this case, the rotor 51 and the circular valve plate 41 do not reach full open due to friction and viscous resistance. In this state, the R / S actuator 50
When the electromagnetic coils 53a to 53d are energized again in the energizing direction (the energizing directions of the electromagnetic coils 53b and 53d are switched) as shown in FIG. 4B, the rotor 51 is attracted and held at the fully open position. . Therefore, the circular valve plate 41 of the intake control valve 40 is also held in the fully opened state. In this way, the above operation (switching of the energizing direction of the electromagnetic coil) is repeated at a desired timing to control the intake air amount for each cylinder of the internal combustion engine. In the intake control device thus configured, the full-open control for controlling the intake control valve 40 to the fully open state is executed under the operation of the ECU 5 when the internal combustion engine is started or at a high speed. In other operations, the opening and closing control for opening and closing the intake control valve 40 for each of the cylinders 1a to 1d is executed in synchronization with the rotation of the internal combustion engine (specifically, the opening and closing state of the intake valve of each cylinder). That is, each of the cylinders 1a to 1
It is not necessary to execute the opening / closing control of the intake control valve 40 at the time of high rotation and high load of the internal combustion engine in which the intake valve of d is optimally opened / closed without generating pumping loss, backflow of intake air, etc. When starting the internal combustion engine, it is necessary to ensure the startability of the internal combustion engine. Therefore, the intake control valve 40 is always controlled to the fully open position to execute the full opening control for securing the intake passage. On the other hand, when the intake control valve 40 is opened and the intake manifolds 2a to 2d are fully opened at a partial load of the internal combustion engine, the intake manifold becomes a negative pressure, a pumping loss occurs, and fuel efficiency deteriorates. At the time of this partial load, the opening / closing control of the intake control valve 40 is performed. The opening / closing control of the intake control valve, which is a feature of the intake control device 4 of the present invention, will be described below with reference to FIG. In FIG. 8, a broken-line mountain indicates an operation state of the exhaust valve.
The peak of the solid line indicates the operation status of the intake valve. In the intake stroke of the internal combustion engine, after an overlap OL period in which both the intake valve and the exhaust valve operated by the high-speed compatible cam are open, the intake control valve 40 is driven from the fully closed state to the fully open state. You. After the intake control valve 40 is held in this fully open state and necessary intake into the cylinder is completed, the intake control valve 40 is driven from the fully open state to the fully closed state before the intake valve closes. These operations are the first opening / closing operation of the intake control valve 40. In this case, since the intake control valve 40 is fully closed before the intake valve closes, the pumping loss is reduced. On the other hand, since the intake valve is closed after the intake control valve 40 is fully closed, a dead volume portion D which is an intake manifold portion between the intake control valve 40 and the intake valve is provided.
(See FIG. 1) is a negative pressure, so that pumping loss may increase at the next intake as it is. Therefore, in the present invention, after the intake valve is closed, the intake control valve 40 is driven again from the fully closed state to the fully open state, and the intake manifold, especially the dead volume portion D is brought to atmospheric pressure. After maintaining this fully open state, before the intake valve starts to open, the intake control valve 40 is again driven from the fully open state to the fully closed state, and this state is maintained. Therefore, exhaust gas does not flow into the intake passage. These operations are the second opening / closing operation of the intake control valve 40. In the present invention, the intake control valve 40 performs the above-described two-stage opening / closing operation during one cycle of the internal combustion engine. As described above, in the intake control apparatus for an internal combustion engine according to the present invention, when both the intake valve and the exhaust valve are open, the intake control valve is closed, so that exhaust gas flows into the intake passage. There is no backflow, and even at the time of a low load, the combustion does not deteriorate and the fuel consumption does not increase. In addition, the intake control valve is fully closed prior to closing the intake valve, and the occurrence of negative pressure in the dead volume part is prevented, so that the next intake can start the intake stroke from atmospheric pressure, reducing pumping loss. it can.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating a system configuration of an internal combustion engine to which an intake control device according to an embodiment of the present invention is applied. FIG. 2 is a longitudinal sectional view of the intake control device according to the embodiment of the present invention. FIG. 3 is a cross-sectional view of a rotary solenoid actuator of the intake control device according to the embodiment of the present invention. 4A and 4B show a magnetic circuit model of the rotary solenoid actuator of the present invention, wherein FIG. 4A is a magnetic circuit model for holding the rotor at a fully closed position, and FIG. 4B is a magnetic circuit model for holding the rotor at a fully open position. It is. FIG. 5 is a schematic diagram of an intake control device according to an embodiment of the present invention. FIG. 6 is a graph showing torque characteristics of a spring. FIG. 7 is a graph showing torque characteristics of the rotary solenoid actuator of the present invention. FIG. 8 is an explanatory diagram of opening / closing control of the intake control device according to the embodiment of the present invention. FIG. 9 is an explanatory diagram of open / close control of a conventional intake control device. [Description of Signs] 1 ... Internal combustion engines 1a to 1d ... Cylinder 2 ... Intake system 2a to 2d ... Intake manifold 3 ... Exhaust system 4 ... Intake control device 40 ... Intake control valve 5 ... ECU OL ... Overlap period D ... Dead volume part

Claims (1)

1. An intake control device for an internal combustion engine, which controls an intake air amount by opening and closing an intake control valve provided in an intake passage of each cylinder of the internal combustion engine at a predetermined timing. The control valve is operated from a fully closed state to a fully opened state after an overlap period of an intake valve and an exhaust valve provided in the cylinder has passed, and after the necessary intake is completed, the intake valve is fully opened before closing. A first opening / closing operation that is operated from a state to a fully closed state; and, after the intake valve is closed, is operated again from a fully closed state to a fully open state to bring the inside of the intake passage to atmospheric pressure and open the intake valve. An intake control apparatus for an internal combustion engine, wherein a second opening / closing operation to be operated again from a fully open state to a fully closed state earlier is performed during one cycle of the internal combustion engine.