JPH03264757A - Intake air control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To substantially reduce a pumping loss by interposing the second open/close valve in a communication path, provided so as to bypass the first open/close valve in an intake passage, and controlling this second open/close valve in accordance with a result of deciding whether an engine speed is less than a predetermined value or not. CONSTITUTION:The second open/close valve F is provided in a communication path E, provided so as to bypass the first open/close valve D for opening/closing an intake passage C connected to an intake valve A of each cylinder, and open/close driven by a drive means G. This drive means G is controlled by the first control means J, so that an intake air flow amount, passing through the second open/close valve F in an opening period of the intake valve A, is larger than an intake air flow amount, passing through the second open/close valve F just after the intake valve A is opened, when an engine speed, detected by an engine speed detecting means H, is decided less than a predetermined value by an engine speed deciding means I. On the other hand, the second open/ close valve F is held to a predetermined opening by the second control means K when the engine speed is decided in a predetermined value or more.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an intake air control device for an internal combustion engine that controls the amount of air taken into a cylinder.

<Prior art> Conventional examples of intake air control devices for internal combustion engines include S, A,
E. There is something like the one shown in Figure 2 of paper 880388.

That is, a rotary valve is interposed in the intake passage upstream of the intake valve, and the rotary valve is opened in synchronization with the opening and closing of the intake valve. When the intake valve and the rotary valve open overlap, air is sucked into the combustion chamber by the downward movement of the piston. Here, pumping loss is reduced by using the rotary valve to bring the air pressure downstream of the rotary valve to approximately atmospheric pressure at the initial stage of opening of the intake valve.

Furthermore, when the volume of the intake passage between the rotary valve and the intake valve is relatively large, a throttle valve is provided in the intake passage upstream of the rotary valve, although the effect of reducing pumping loss is reduced (S, A).

°E, see Figure 9 of paper 880388). and,
By throttling the air with a throttle valve and lowering the pressure in the intake passage below atmospheric pressure in advance, the combustion chamber pressure when the piston is at bottom dead center can be reduced to -5, for example, during idling operation.
50,,H, can be set.

Furthermore, Japanese Patent Application Laid-Open No. 148932/1984 is a method that includes a rotary valve upstream of the intake valve.

<Problems to be Solved by the Invention> However, in such conventional intake air control devices, a rotary valve is provided in series with the intake valve, so a gear is required to change the rotational phase of the rotary valve. Because it is a complex structure that requires multiple pieces to be combined, lI! There is a problem in that the friction loss is large and the overall effect of reducing pumping loss is reduced. Further, due to the complicated structure, it is difficult to control the intake air flow rate for each cylinder.

In order to solve this problem, the applicant of the present application filed the patent application No. 1-29
In No. 6072, on-off valves are interposed in the bypass passages of the throttle valves provided independently for each cylinder, and these on-off valves are driven to open and close by electromagnetic actuators in response to the opening and closing of the intake valves, thereby reducing the load in the low load range. We have proposed a system that controls the intake air flow rate while reducing pumping loss. However, the response speed of electromagnetic actuators is fast, 20 to 30□S-
In addition, there is a delay in the response of the intake air supply due to the inertia of the intake air, so when the on-off valve is opened and closed in a high rotation range, the response delay makes the intake air flow rate control inaccurate, and there is still room for improvement.

To explain this specifically, for example, the engine rotation speed is 10
00. When , , , , the -stroke is about 120. ,
c, and it is possible to control the intake air flow rate even if the response delay is taken into account. However, the engine rotation speed is 5000. , ,,
,.

When -stroke is 24. s-, the intake air flow rate control becomes inaccurate due to the response delay. In such a state,
If you try to open and close the on-off valve in response to the opening and closing of the intake valve in a high rotation range, the response delay will cause the on-off valve to open and close repeatedly before the intake air flow rate has changed much. It is not possible to increase the flow rate of intake air passing through the opening/closing valve during the closing period of the intake valve. For this reason, when the throttle valve is fully closed in a high rotation range, the pressure in the combustion chamber during the intake stroke becomes a high negative pressure, causing a problem such as oil rising into the combustion chamber.

The present invention has been developed in view of the above-mentioned circumstances, and it is possible to control the intake air flow rate for each cylinder with a simple configuration while maintaining the output torque (engine speed) at an optimum level during low-load operation such as idling. An object of the present invention is to provide an intake air control device for an internal combustion engine that can control the air and prevent oil leakage in a high rotation range.

<Means for Solving the Problems> For this reason, the present invention, as shown in FIG. A first on-off valve that opens and closes the intake passage IaC that is provided and communicates with the intake valve A of each cylinder; a communication passage E that communicates at least with the intake passage C downstream of each first on-off valve; A second on-off valve F that opens and closes, a driving means G that drives each of the second on-off valves, a rotation speed detection throttle valve H that detects the engine rotation speed, and a detection throttle valve H that detects whether the detected engine rotation speed is equal to or higher than a predetermined value. A rotational speed determining means 1 for determining the engine rotational speed is configured such that when the engine rotational speed is determined to be less than a predetermined value, the intake pressure downstream of the first opening/closing valve is approximately equal to the atmospheric pressure cam at the time when the intake valve A is opened. The flow rate of intake air passing through the second on-off valve F during the period from when the intake valve closes to when the intake valve opens is determined by controlling the intake air flow rate to the second on-off valve F immediately after the intake valve A opens.
'i! a first control means J that controls the second on-off valve F in accordance with the opening/closing operation of the intake valve six to increase the flow rate of intake air to be greater than the flow rate of intake air passing through the engine; a second control means for maintaining the second opening/closing valve F at a predetermined opening degree regardless of the opening/closing operation of the intake valve A;
We prepared the following.

<Operation> In this way, the intake air downstream of the first on-off valve! A second on-off valve is interposed in the communication path communicating with the airway, and when the engine speed is less than a predetermined value, the flow rate of intake air passing through the second on-off valve during the period from when the intake valve closes to when the intake valve opens is controlled. The second on-off valve is controlled so that the intake air flow rate is greater than the intake air flow rate immediately after the intake valve opens.

As a result, the intake pressure change in the combustion chamber during the intake stroke is optimally controlled, greatly improving the effect of reducing pumping loss.This allows the engine to maximize its output torque, especially during low-load operation, and allows each cylinder to The intake air flow rate can now be controlled.

Furthermore, when the engine speed is above a predetermined value, the second on-off valve is held at a predetermined opening regardless of the opening/closing operation of the intake valve, thereby controlling the flow rate of intake air passing through the second on-off valve to a predetermined amount. This ensures a sufficient flow of intake air while preventing high negative pressure in the combustion chamber and preventing oil leakage.

<Example> An example of the present invention will be described below based on FIGS. 2 to 13. In this embodiment, a four-cylinder internal combustion engine will be described as an example.

In FIGS. 2 and 3, a butterfly-type throttle valve 2 as a first opening/closing valve that is linked to the depression of an accelerator pedal is arranged in series with an intake valve 3 in an intake passage 1 that is independent for each cylinder. A bypass passage 4 as a communication passage that bypasses each throttle valve 2 is formed between each throttle valve 2 . A second on-off valve 5 is interposed in each of the bypass passages 4, and the second on-off valve 5 is driven to open and close by an electromagnetic actuator 5A serving as a driving means. A control signal is input from the control device 6 to the actuator 5A. Here, the volume of the intake passage 1 from the throttle valve 2 to the intake valve 3 is set to about 172, which is the maximum volume of the combustion chamber (combustion chamber volume when the piston is at the bottom dead center).

The control device 6 receives a reference signal (every 180 degrees in crank angle) and a position signal (for example, every 1 degree in crank angle) from a crank angle sensor 7, and a signal embedded in the washer of the spark plug 8 of each cylinder. cylinder pressure sensor (not shown)
The in-cylinder pressure detection signal from is input.

The control device 6 controls the engine rotation speed to a predetermined value (for example, 20
00. , , , , , ), Figures 4 to 7
It operates according to the flowchart shown in the figure, and outputs a control signal to the actuator 5A to control the opening and closing of the second on-off valve in accordance with the opening and closing operations of the intake valve 3.

Further, when the intake valve is at or above the predetermined value, the control device 6 adjusts the second opening to the target opening set according to the engine rotation speed.
The on-off valve 5 is controlled to be held regardless of the opening/closing operation of the intake valve 3.

Here, the control device 6 constitutes the rotational speed determination means and the first and second control means.

Note that 9 is a fuel injection valve.

Next, the effect will be explained.

First, the operation when the engine rotational speed is less than a predetermined value will be explained according to the flowcharts shown in FIGS. 4 to 7. here,
The routines shown in the flowcharts of FIGS. 4 and 7 are executed by the interrupt routine number each time a reference signal is input from the crank angle sensor 7 as shown in FIG. ). Also,
The routine shown in the flowchart in Fig. 5 is executed by an interrupt routine when the set crank angle (near the top dead center of #l cylinder), which will be described later, is reached as shown in Fig. 8 (crank job in Fig. 8). ).

The routine shown in the flowchart of FIG. 6 is always executed when the interrupt routine is not executed.

First, the flowchart shown in FIG. 4 will be explained.

At Sl, the set crank angle for executing the routine shown in the flowchart of FIG. 5 is set. As shown in FIG. 9, this set crank angle is set to a value near the top dead center immediately before the start of combustion of the air-fuel mixture (start of ignition) in the compression stroke of the #1 cylinder.

In S2, it is determined from the reference signal whether or not it is the #1 cylinder. If YES, the process proceeds to S3; if NO, the process proceeds to S6.

In S3, 1 is added to the variable counter value and the process proceeds to S4.

In S4, it is determined whether or not the added variable counter value has reached 3. If YES, the process proceeds to S5, and if NO, the process proceeds to S6.

In S5, the variable counter value is initialized to O.

Therefore, the variable counter values are 0, 1.2, 3°0.
1.2 is repeated, and the value is switched when the reference signal is input when the #1 cylinder is in the compression stroke.

In S6, the combustion chamber pressure read in the routine described later is
Each cylinder is stored in a memory (RAM) at an address corresponding to the variable counter value. Therefore, for each cylinder,
Four combustion chamber pressure data are stored in the memory as shown by the broken lines in FIG. Then, the combustion chamber pressure is sequentially rewritten from old data to new data.

In S7, the average combustion chamber pressure (indicated by the thin line in FIG. 10) is calculated by simply averaging the four pieces of data stored in the memory for each cylinder.

Next, to explain the flowcharts of FIGS. 5 and 6, in Sll of FIG. 5, an A/D converter (not shown) is activated for each set crank, and the cylinder pressure sensor detects Read the combustion chamber pressure just before the start of combustion. Here, the output torque of the engine is predicted from the combustion chamber pressure just before the start of combustion. Further, at 321 in FIG. 6, the engine rotational speed is read based on the manual cycle of the reference signal from the crank angle sensor 7.

Next, the flowchart shown in FIG. 7 will be explained.

In S31, the rotational difference NVAR between the engine rotational speed read in S21 and the target rotational speed is calculated.

In S32, the calculated rotational difference NVAR is added to the previous rotational integral value 12 to calculate a new rotational integral value. Further, NPI is calculated by adding the integral obtained by multiplying the newly obtained rotation integral value by a constant KIO and the proportional component obtained by multiplying the rotation difference NVAR by a constant Kll.

In S33, the average combustion chamber pressure of each cylinder calculated in S7 is added and then divided by the number of cylinders to calculate the total average combustion chamber pressure TOTALAVE.

In S34, the total average combustion chamber pressure T○TA is determined for each cylinder.
The deviation CYLVAR is calculated by subtracting the average combustion chamber pressure of that cylinder from LAVE. Furthermore, a new CYL integral value is calculated for each cylinder by adding the deviation CYLVAR calculated for each cylinder and the previous CYL integral value. moreover,
By adding the integral of the calculated CYL integral value to the constant multiplied by 20 and the proportional part of the constant multiplied by 21 to the deviation CYLVAR, the output torque of all cylinders is determined to be approximately the same for each cylinder by CYLPI. Calculate it so that it becomes.

In S35, the calculated CYLPI and the value obtained by multiplying the NPI by 30 are added to calculate the control value of the actuator 5A for each cylinder.

Then, a control signal corresponding to the calculated control value is output to the actuator 5A of the corresponding cylinder, and the second on-off valve 50
The opening degree is controlled for each cylinder.

Changes in the opening degree of the second on-off valve 5 and changes in the intake pressure downstream of the throttle valve 2 during such control will be explained with reference to the time chart of FIG. 11. In this explanation, the case is taken when the throttle valve 2 is fully closed, that is, during idling operation. shows.

That is, at the start of the intake stroke when the intake valve 3 begins to open, the second on-off valve 5 is fully opened from the compression stroke to the explosion stroke so that the intake pressure downstream of the throttle valve 2 becomes atmospheric pressure. As a result, the intake pressure downstream of the throttle valve 2 is determined by the intake pressure at the bottom dead center of the piston during the intake stroke (the intake pressure at the end of the intake stroke, as shown in Fig. 550~-570□H9 to near atmospheric pressure.

Here, if the second opening/closing valve 5 is always maintained at a constant opening and opened so that the intake pressure at the start of the intake stroke becomes atmospheric pressure, the intake pressure becomes as shown in A in Fig. 11, and the combustion chamber The intake air flow rate sucked into the unit becomes higher than the desired value. Also,
The intake pressure at the bottom dead center of the piston is -550 to -570 as mentioned above.
If the opening degree of the second on-off valve 5 is always set small so that ,,H, the intake pressure at the start of the intake stroke becomes B in Fig.
The pressure does not reach atmospheric pressure as shown in .

Therefore, in this embodiment, when the intake valve 3 opens, the opening degree of the second on-off valve 5 is driven to close from fully open to a predetermined opening degree. As a result, as shown in C in Fig. 11, the intake pressure at the time when the intake valve 3 opens is set to near atmospheric pressure, the intake pressure at the end of the intake stroke is set to a predetermined value, and the intake air flow rate is set to a predetermined value. This allows it to be set to . Specifically, the second on-off valve 5 is fully opened during the opening/closing period of the intake valve 3, and immediately before the intake valve 3 opens, the second on-off valve 5 is closed to a predetermined opening degree.

By controlling the opening degree of the second on-off valve 5 in this manner, the opening degree of the second on-off valve 5 can be simply controlled in proportion to the engine rotation speed. This means that when the intake pressure at the start of the intake stroke is atmospheric pressure, the intake air flow rate can be determined from the ratio of the volume of the intake passage 1 downstream of the throttle valve 2 and the volume of the combustion chamber, which increases as the piston descends. This allows the shortfall to be replaced by the second
This is because it can be compensated for by controlling the opening degree of the on-off valve 5.

Here, the reason why the closing timing of the second on-off valve 5 is set before the start of the intake stroke (at the beginning of the exhaust stroke) in FIG. 11 is to take into account the response delay of the control system. In reality, the second opening/closing valve 5 is switched to a predetermined opening degree immediately before the intake valve 3 opens.

Next, the operation when the engine rotational speed is equal to or higher than a predetermined value will be explained.

When the engine speed detected by the crank angle sensor 7 exceeds a predetermined value, the control device 6 searches the map for the target opening degree of the second on-off valve 5 based on the detected engine speed. As shown in FIG. 12, this target opening degree is set to increase as the engine rotation speed increases.

Then, the control 6 controls the opening degree of the second on-off valve 5 of the gold cylinder to be maintained at the target opening degree regardless of the opening/closing operation of the intake valve 3 via the electromagnetic actuator 5A.

Incidentally, the intake air flow rate of the bypass passage 4 may be controlled as described above by controlling the actuator 5A using an on/off duty signal.

Next, an example of the hardware configuration of the control device 6 will be explained as follows.
This will be explained based on Figure 3.

That is, after the cylinder pressure at a predetermined crank angle is averaged for each cylinder by the averaging processing circuits 11A to 11D, the adder 12 adds them together.

Then, the added cylinder pressure of all the cylinders is divided by the number of cylinders by the divider 13 to calculate the average pressure of the gold cylinders.

After calculating the pressure difference for each cylinder by subtracting the average pressure for each cylinder from the calculated average pressure of all cylinders using differentiators 14A to 14B, the proportional and integral parts of the pressure difference for each cylinder are calculated. are calculated by the PI processing circuits 15A to 15D, respectively.

Further, after the difference between the actual engine rotation speed detected by the crank angle sensor 7 and the target rotation speed is calculated by the differentiator 16, the proportional part and the integral part of this rotation speed difference are calculated by the PI processing circuit 17. calculate. Then, adders 18A to 18D add the proportional and integral parts of the pressure difference and the proportional and integral parts of the rotational speed difference to obtain a correction value for each cylinder, which is then input to one of the changeover switches 19A to 19D. Manually connect the terminal.

Further, a target opening degree setting section 20 is provided which sets a target opening degree from the detected engine rotational speed, and the set target opening degree is inputted to other input terminals of the changeover switches 19A to 19D. Further, a rotation speed determining section 21 is provided that determines whether the detected engine rotation speed is equal to or higher than a predetermined value. This rotational speed determination section 21 outputs the correction value of the adders 18A to 18B when the engine rotational speed is less than a predetermined value, and outputs the correction value from the target opening degree setting section 20 when the engine rotational speed is equal to or higher than the predetermined value. The changeover switches 19A to 19D are controlled so as to output the target opening degree.

As explained above, the second on-off valve 5 is provided for each cylinder in the bypass passage 4 that bypasses the throttle valve 2, and the volume of the intake passage 1 downstream of each throttle valve 2 is set to 27% of the maximum volume of the combustion chamber.
1 and when the engine speed is less than a predetermined value, the second on-off valve 5 is fully opened so that the intake pressure downstream of the throttle valve 2 at the time the intake valve 3 opens is close to atmospheric pressure, and during the intake stroke. Since the second on-off valve 5 is driven to close to a predetermined opening degree, the following effects can be obtained.

That is, when the intake valve 3 begins to open, the combustion chamber pressure (
Since the intake pressure in the intake passage 1 is maintained near atmospheric pressure, as the piston descends, the combustion chamber pressure changes from atmospheric pressure to the combustion chamber pressure at the bottom dead center position of the piston during idling (for example, = It decreases approximately linearly from 550 to -570□HI).

Therefore, pumping loss can be significantly reduced compared to changes in intake pressure due to conventional throttle valve control alone, and the engine output can be maximized. Furthermore, since the second on-off valve 5 of the bypass passage 4 is controlled by the electromagnetic actuator 5A, the structure can be simplified compared to the conventional one.

Here, the reason why the volume of the intake passage 1 extending from the throttle valve 2 to the intake valve 3 is set to 172 mm or less, which is the maximum volume of the combustion chamber, will be explained. The maximum volume of the combustion chamber is set as A, the volume of the intake passage 1 from the throttle valve 2 to the intake valve 3 is assumed to be B, the compression ratio is assumed to be 1710, and the piston bottom dead center position during idle operation is Combustion chamber pressure (intake pressure) -45
6,,H, (in a high-speed engine, the valve over-ramp period is long, so the value will be about this value).

That is, the total volume of the intake passage 1 and the combustion chamber at the top dead center of the piston is (A/10+B), and the total volume of the intake passage 1 and the combustion chamber at the bottom dead center of the piston is ( A+B). When the combustion chamber pressure and intake pressure change from atmospheric pressure (1 atm) to -450, H9 (0.4 atm) under such conditions, (A/10+B)/
(A + B) = 0.4, and solving this gives A = 2B.

Therefore, when the volume of the intake passage 1 is less than or equal to the maximum volume of the combustion chamber, which is about 172, it is possible to ensure the optimal combustion chamber pressure at the bottom dead center position of the piston during low load operation such as during idling operation.

In addition, since the deviation (deviation) CYLVAR is calculated for each cylinder from the total average combustion chamber pressure TOTALAVE of the golden cylinder, the combustion chamber pressure of each cylinder approaches the total average combustion chamber pressure TOTALAVE. Combustion pressure can be made almost the same with a gold cylinder. This allows the output torques of the gold cylinders to be made substantially the same, making it possible to stabilize the drivability during idling operation. Further, after determining the rotational difference (deviation) NVAR of the engine rotational speed of each cylinder from the target rotational speed, NPI is determined for each cylinder, and the NPI that depends on the engine rotational speed is added to the control value of the actuator 5A. This also makes it possible to stabilize the drivability during actuator operation.

In addition, since the control value of the actuator 5A is determined for each combustion stroke (reference signal) in each cylinder, the output torque and engine speed can be made almost the same in each cylinder, and this also allows drivability can be stabilized.

Furthermore, when the engine speed is above a predetermined value, the second on-off valve 5 is held at the target opening set according to the engine speed, regardless of the opening/closing operation of the intake valve 3. Since the intake air flows through the second on-off valve 5 even at high speeds, it is possible to prevent the combustion chamber pressure from becoming an excessively high negative pressure even if the throttle valve 2 is fully closed in the high speed range.
This prevents oil from rising.

In the example, the output torque of the engine was predicted from the combustion chamber pressure, but the intake pressure, intake air flow rate,
The second on-off valve may be controlled based on the air-fuel ratio of the engine (for example, a detection signal from an oxygen sensor that detects the air-fuel ratio from the oxygen concentration in exhaust gas) or the actual output torque. In addition, a second on-off valve is interposed in the bypass passage that bypasses the throttle valve, but for example, an external pressure accumulating tank is connected to the intake passage downstream of the throttle valve, and a second on-off valve is installed in this communication passage. An on-off valve may be provided.

<Effects of the Invention> As explained above, the present invention includes a second on-off valve interposed in the communication passage communicating with the intake passage downstream of the first on-off valve provided for each cylinder, so that the engine rotation speed is maintained at a predetermined level. When the value is less than the value, the intake air flow rate passing through the second opening/closing valve during the period from when the intake valve closes until it opens is made larger than the intake air flow rate immediately after the intake valve opens, and the intake valve opens. Since the second on-off valve is controlled so that the intake pressure downstream of the first on-off valve is close to atmospheric pressure at the moment, the pumping loss can be significantly reduced with a simple configuration and the output torque during low-load operation can be increased. It is possible to improve the intake air amount for each cylinder and to control the amount of intake air for each cylinder.

In addition, when the engine rotational speed is above a predetermined value, the second on-off valve is held at a predetermined opening regardless of the opening/closing operation of the intake valve, so that the second on-off valve is held at a predetermined opening so that the predetermined amount of intake air flows through the second on-off valve. Even if the first on-off valve is fully closed during rotation, the combustion chamber pressure can be prevented from becoming an excessively high negative pressure, and oil leakage can be prevented.

[Brief explanation of drawings]

Fig. 1 is a diagram corresponding to the claims of the present invention, Fig. 2 is a constituent country showing an embodiment of the present invention, Fig. 3 is an enlarged view of the main parts of the same, and Fig. 4 is a diagram corresponding to the claims of the present invention.
7 to 7 are flowcharts of the same, FIGS. 8 to 12 are diagrams for explaining the operation of the same, and FIG. 13 is a hardware configuration diagram of the same. 1... Intake passage 2... Throttle valve 4... Bypass passage 5... Second on-off valve 5A... Electromagnetic pressure 6... Control device

Claims (1)

[Claims] In an internal combustion engine in which an intake valve is opened when a piston descends to draw air into a combustion chamber, a first on-off valve is provided for each cylinder and opens and closes an intake passage communicating with the intake valve of each cylinder; A communication passage that communicates with at least the intake passage downstream of the on-off valve, and a second on-off valve that opens and closes each of these communication passages, respectively;
A driving means for driving each second on-off valve, a rotational speed detection means for detecting the engine rotational speed, a rotational speed determination means for determining whether the detected engine rotational speed is equal to or higher than a predetermined value, When the intake valve is determined to be less than a predetermined value, the second on-off valve is operated during the period from when the intake valve closes to when the intake valve opens so that the intake pressure downstream of the first on-off valve becomes approximately atmospheric pressure when the intake valve opens. The second on-off valve is controlled in accordance with the opening/closing operation of the on-off valve so that the flow rate of intake air passing through the intake valve is greater than the flow rate of intake air passing through the second on-off valve immediately after the intake valve opens. a first control means; and a second control means for maintaining the second on-off valve at a predetermined opening degree regardless of the opening/closing operation of the intake valve when the engine rotational speed is determined to be equal to or higher than a predetermined value. An intake air control device for an internal combustion engine, characterized in that: