JP4193753B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine for an automobile.

  Modern automobiles are almost equipped with a brake booster that allows a large braking force to be obtained even with a light braking force. As will be described in detail later, the brake booster has a constant pressure chamber and a variable pressure chamber partitioned by a diaphragm, a power piston is attached to the diaphragm, and the pressure supplied to the constant pressure chamber and the variable pressure chamber is applied to the power piston. A differential pressure switching mechanism for switching the differential pressure between the constant pressure chamber and the variable pressure chamber by switching according to whether the brake is ON (the brake pedal is depressed) or the brake is OFF (the brake pedal is not depressed) is attached.

  The constant pressure chamber communicates with the suction pipe, and intake negative pressure is always introduced into the constant pressure chamber. The differential pressure switching mechanism allows the constant pressure chamber and the variable pressure chamber to communicate with each other when the brake is OFF, shuts off the air flow into the variable pressure chamber, leads the intake negative pressure to the variable pressure chamber, and eliminates the differential pressure between the constant pressure chamber and the variable pressure chamber. When ON, the communication between the constant pressure chamber and the variable pressure chamber is cut off, and the variable pressure chamber operates so that atmospheric pressure is introduced. However, the above-described differential pressure switching mechanism has a problem that the air in the variable pressure chamber flows into the constant pressure chamber and flows into the suction pipe when the brake is turned on and off, that is, when the brake pedal that has been depressed is released. is there.

  On the other hand, most internal-combustion engines in modern automobiles are electronically controlled and include an air flow meter to detect the amount of intake air. This air flow meter is usually provided in the air cleaner or at a position immediately downstream of the air cleaner. However, the negative pressure introduction pipe for introducing a negative pressure into the constant pressure chamber of the brake booster is usually connected to a portion immediately before the intake pipe of the engine called a surge tank.

  Therefore, as described above, when air flows into the intake pipe from the brake booster, more air than the amount of air measured by the air flow meter is introduced into the combustion chamber of the engine, and correct control cannot be performed.

  Further, even if the brake is not in the transition state from ON to OFF as described above, for example, when the brake is turned ON, the accelerator pedal is naturally not depressed, and the negative pressure of the suction pipe increases. However, if the value is larger than the negative pressure value stored in the constant pressure chamber of the brake booster, the air in the constant pressure chamber is introduced into the suction pipe.

  Patent Document 1 discloses a device that performs fuel injection amount correction for a predetermined time from brake ON → OFF based on a brake ON / OFF signal and a rotation speed during low load operation including idling. In this device, the fuel injection amount at the time of brake ON → OFF is corrected, but the air amount is not calculated. Therefore, the control depending on the air amount other than the fuel injection amount becomes inaccurate. In addition, the above-mentioned problem when the brake is ON cannot be dealt with.

  Patent Document 2 describes air that flows into the variable pressure chamber from the pressure in the variable pressure chamber, based on the idea that the same amount of air that flows into the variable pressure chamber of the brake booster is introduced into the suction pipe when the brake is turned on. An apparatus for calculating an amount and estimating an amount of excess air flowing into the suction pipe based on the calculated amount is disclosed. Therefore, although the amount of air at the time of brake ON → OFF can be estimated, the above-mentioned problems at the time of brake ON cannot be dealt with.

  In the device of Patent Document 3, the flow rate of air flowing into the suction pipe from the brake booster is determined based on the pressure in the suction pipe and the pressure in the constant pressure chamber of the brake booster. Therefore, it seems that the problem at the time of brake ON mentioned above can also be dealt with. However, in addition to the air flow meter, it is necessary to provide an intake pressure sensor in both the intake pipe and the constant pressure chamber of the brake booster, which increases costs.

Japanese Utility Model Publication 3-45445 JP-A-7-19086 JP 2002-97989 A

  In view of the above problems, an object of the present invention is to reliably detect, at a low cost, the amount of air introduced into a combustion chamber when air flows into a suction pipe from a brake booster in accordance with a brake operation.

According to invention of Claim 1, it is an internal combustion engine for vehicles, Comprising: A brake booster is provided,
The brake booster communicates with the negative pressure intake part of the suction pipe, the constant pressure chamber where the negative pressure of the suction pipe always acts, the variable pressure chamber arranged adjacent to the constant pressure chamber, and the constant pressure chamber and the variable pressure chamber when the brake is OFF. This shuts off the introduction of atmospheric pressure into the transformer room, shuts off the communication between the constant pressure chamber and the transformer room when the brake is on, and introduces the atmosphere into the transformer room. And having a differential pressure switching mechanism,
First intake air amount detection means for detecting the intake air amount upstream of the negative pressure intake portion;
A second intake air amount detection means for detecting an intake air amount downstream of the negative pressure intake portion;
Brake on / off judging means for judging whether the brake is on or off,
Comprising
When the brake is OFF and a predetermined time has elapsed after the brake is turned ON, the air amount is calculated based on the detection value of the first intake air amount detection means,
An internal combustion engine is provided that calculates an air amount based on a detection value of a second intake air amount detection means when the brake is ON and when a predetermined time has not elapsed after the brake is turned ON.

  In the internal combustion engine configured as described above, the air amount is calculated based on the value detected upstream from the negative pressure intake portion of the suction pipe when the brake is OFF and a predetermined time has elapsed after the brake is turned ON. However, when the brake is turned on and when the predetermined time has not elapsed since the brake was turned on, the amount of air is based on the value detected downstream from the negative pressure intake portion of the suction pipe through which air flows from the brake booster. Is calculated.

  In the invention of claim 2, in the invention of claim 1, one of the first intake air amount detection means and the second intake air amount detection means is an intake air flow rate detection means for detecting the intake air flow rate, and the other is the intake air. Intake air pressure detection means for detecting the air pressure.

  According to a third aspect of the invention, in the second aspect of the invention, the air amount is calculated based on the detected values detected simultaneously by the intake air pressure detecting means and the intake air flow rate detecting means, and is calculated based on the detected values of the intake air pressure detecting means. Correction means for correcting the air amount so as to be the same as the air amount calculated based on the detection value of the intake air flow rate detection means is provided. Therefore, the air amount calculated based on the detected value of the intake air pressure detecting means has the same accuracy as the air amount calculated based on the detected value of the intake air flow rate detecting means.

  According to the invention of claim 4, in the invention of claim 3, when the brake is OFF and a predetermined time has elapsed after the brake is turned ON → the air is simultaneously detected by the intake air pressure detection means and the intake air flow rate detection means. Detect the amount, and so on. Therefore, correction is performed correctly.

  According to the invention of claim 5, in the invention of claim 1, there is provided an internal combustion engine in which the air quantity is always detected by both the first intake air quantity detection means and the second intake air quantity detection means. .

  In the invention described in each claim, the air amount is calculated based on a value detected upstream from the negative pressure intake portion of the suction pipe when the brake is OFF and a predetermined time has elapsed after the brake is turned ON. However, when the brake is ON and when a predetermined time has not elapsed since the brake is turned ON, the air amount is determined based on the value detected downstream from the negative pressure intake portion of the suction pipe through which air flows from the brake booster. Calculated. Therefore, even when air flows in from the brake booster, the amount of air guided to the combustion chamber of the engine can be calculated correctly.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing a hardware configuration common to the embodiments of the present invention.
Reference numeral 1 denotes a spark ignition type internal combustion engine (hereinafter referred to as an engine), and the engine 1 includes a cylinder head 1a and a cylinder block 1b. The cylinder head 1 a includes an intake port 5, an exhaust port 6, an intake valve 7, an exhaust valve 8, and an ignition plug 40, and a high voltage current is supplied to the ignition plug 40 from an ignition coil 41. A crank angle sensor 50 used for detecting the engine speed is attached to the cylinder block 1b.

An intake manifold 10 is connected to the intake port 5, and an exhaust manifold 20 is connected to the exhaust port 6. A second suction pipe (surge tank) 11 and a first suction pipe 12 are sequentially connected to the intake manifold 10 upstream, and an air cleaner 13 is attached to the most upstream end. A fuel injection valve 30 is disposed in the intake manifold 10, and a throttle valve 14 is interposed in the intake pipe 12.
An air flow meter 51 is disposed in the first suction pipe 12 immediately downstream of the air cleaner 13, and an intake pressure sensor 52 is disposed in the second suction pipe 11. A negative pressure introduction pipe 114 that introduces a negative pressure into the constant pressure chamber 110 of the brake booster 100 is attached to the negative pressure intake portion 11 a that is disposed upstream of the intake pressure sensor 52.

  An exhaust manifold 20 is connected to the exhaust port 6, and a first exhaust pipe 21 and a second exhaust pipe 22 are sequentially connected to the exhaust manifold 20 toward the downstream side. A three-way catalyst 23 is disposed inside the first exhaust pipe 21. A first air-fuel ratio sensor 24 is disposed near the upstream side of the three-way catalyst 23, and a second air-fuel ratio sensor 25 is disposed near the downstream side of the three-way catalyst 21.

  The exhaust gas generated in the combustion chamber 1c is led to the exhaust manifold 20 through the exhaust port 6 whose flow path is opened and closed by the exhaust valve 8, and further purified by the three-way catalyst 23 in the first exhaust pipe 21, before the first. 2 Exhaust through the exhaust pipe 22. Based on the outputs of the first air-fuel ratio sensor 24 and the second air-fuel ratio sensor 25, the fuel injection amount injected from the fuel injection valve 30 is feedback-controlled so that a predetermined air-fuel ratio is obtained.

The upstream side of the intake pressure sensor 52 of the surge tank 11 and the constant pressure chamber 110 (see FIG. 2) of the brake booster 100 are connected by a negative pressure introduction pipe 114.
A brake switch 53 for detecting whether the brake pedal 150 is depressed or not is attached to the brake lever 151. When the brake pedal 150 is depressed, the hydraulic pressure pressurized in the master cylinder 130 attached to the brake booster 100 is sent to the wheel cylinder 135 via the brake pipe 132, and the wheel cylinder 135 is the axle of the tire 136. The brake disc 138 attached to 137 is tightened to perform braking.

  An electronic control unit (hereinafter referred to as ECU) 70 is formed by connecting an input port 71, a CPU 72, a ROM 73, a RAM 74, an output port 75, and the like with a common bus. A signal detected by each sensor according to the present invention is input to the ECU 70, and a control signal for performing control related to the present invention is sent to each actuator. In addition, control signals are exchanged with sensors and actuators for various controls not related to the present invention, but the description is omitted.

  Next, details of the brake booster 100 will be described. FIG. 2 is a diagram showing a configuration of one example of the brake booster 100 in a state in which the brake pedal is not depressed, and has a constant pressure chamber 110 and a variable pressure chamber 120, and the constant pressure chamber 110 and the variable pressure chamber 120 are diaphragms 115. Separately, a power piston 116 is attached to the diaphragm 115. The power piston 116 is urged toward the variable pressure chamber 120 by a spring 112 provided in the constant pressure chamber 110.

  A master cylinder 130 is attached to the outer wall 111 of the constant pressure chamber 110 to pressurize a hydraulic pressure that leads to a brake cylinder (not shown). The constant pressure chamber 110 is communicated with the suction pipe 12 by a negative pressure introduction pipe 114 attached via a one-way valve 113.

  A communication state switching mechanism 140 is integrally attached to the central portion of the power piston 116. The communication state switching mechanism 140 includes a block portion 140A on the left side in the drawing and a hollow chamber forming portion 140B on the right side in the drawing. A cylinder 141 is formed at the center of the block portion 140A, and a valve plunger 142 is slidably provided inside the cylinder 141.

  The left end portion of the cylinder 141 is enlarged in diameter, and a reaction disk 143 is slidably provided there. A reaction rod 144 is attached to the reaction disk 143, and the tip of the reaction rod 144 is in contact with the master cylinder piston 151 in the master cylinder 150.

  Meanwhile, the hollow chamber forming portion 140B is provided with a poppet valve 146 supported at one end of a valve support member 145 made of a flexible material, and the other end of the valve support member 145 is disposed on the inner surface of the hollow chamber forming portion 140B. It is fixed. The poppet valve 146 is notched at the center, and the outer peripheral portion of the remaining portion can be brought into contact with the right end surface of the block portion 140A, and the inner peripheral portion thereof can be brought into contact with the right end surface of the valve plunger 142. ing.

  Further, the central portion of the right end wall of the hollow chamber forming portion 140B is cut out larger than the diameter of a valve drive rod 162 described later, and the atmosphere and the hollow chamber forming portion 140B can communicate with each other, but dust or the like is contained inside. In order to prevent intrusion, a filter 149 made of a sponge-like porous material capable of air flow is provided.

  And the inside of the constant pressure chamber 110 and the hollow chamber formation part 140B is connected by the 1st communicating hole 147 which penetrates the block part 140A. Further, the variable pressure chamber 120 and the cylinder 141 in the block portion 140A communicate with each other through the second communication hole 148.

  On the other hand, the brake pedal 150 is attached to the pedal lever 151, and the valve drive rod 152 is attached to the pedal lever 151. The valve drive rod 152 extends into the communication state switching mechanism 140, and the tip thereof is engaged with the valve plunger 142. The valve drive rod 152 is urged to the right side (the brake pedal non-depressing direction) by the first rod spring 153. Further, the second rod spring 154 urges the poppet valve 146 toward the block portion 140A.

  FIG. 3A is a diagram showing the inside of the communication state switching mechanism 140 when the brake pedal is not depressed, and the poppet valve 146 is in contact with the right end surface of the valve plunger 142, but the block portion 140A It is not in contact with the right end surface of. Accordingly, the air that has passed through the filter 149 cannot enter the cylinder 141, while the constant pressure chamber 110 and the variable pressure chamber 120 are communicated via the first communication path 147, the cylinder 141, and the second communication path 148, and the constant pressure chamber 110 and the variable pressure chamber 120 both have the same pressure as the suction pipe negative pressure. Therefore, the power piston 116 is pressed to the right end position by the force of the spring 112, does not press the piston 131 of the master cylinder 130, and does not operate the brake.

  FIG. 3B is a diagram showing the inside of the communication state switching mechanism 140 when the brake pedal is depressed. The poppet valve 146 does not contact the right end surface of the valve plunger 142, but the right end surface of the block portion 140A. Is in contact. Therefore, the communication between the constant pressure chamber 110 and the cylinder 141 is cut off, and the communication with the variable pressure chamber 120 is not established.

  On the other hand, the air that has passed through the filter 146 passes through the notch of the poppet valve 146 and the gap between the left end surface of the poppet valve 146 and the right end surface of the valve plunger 142, enters the cylinder 141, and further The variable pressure chamber 120 is entered through the communication path 148. Since the constant pressure chamber 110 becomes negative pressure in the suction pipe and the variable pressure chamber 120 becomes atmospheric pressure, the power piston 116 is moved to the left and presses the piston 131 of the master cylinder 130 to operate the brake.

(C) in FIG. 3 occurs instantaneously at the time of transition from the state (B) to the state (A). In this case, there is a gap between the left end surface of the poppet valve 146 and the right end surface of the block portion 140A. Accordingly, in this case, the air in the variable pressure chamber 120 flows into the constant pressure chamber 110 and further flows into the second suction pipe 11 from the negative pressure intake portion 11a via the negative pressure introduction pipe 114.
Further, when the suction pipe negative pressure is larger than the negative pressure in the constant pressure chamber 110 (the pressure is lower) during the transition from (A) to (B), the air in the constant pressure chamber 110 is similarly taken into the second suction. It flows into the tube 11.

  The air flow meter 51 is provided at a position immediately downstream of the air cleaner 13 and is upstream of the negative pressure intake portion 11a, and the intake pressure sensor 52 is downstream of the negative pressure intake portion 11a. Therefore, the detected value of the air flow meter 51 does not include the air that flows into the second suction pipe 11 from the variable pressure chamber 110 of the brake booster 100. On the other hand, the detected value of the intake pressure sensor 52 includes air flowing into the second intake pipe 11 from the variable pressure chamber 110 of the brake booster 100.

Hereinafter, each embodiment of the present invention configured as described above will be described.
First, the first embodiment will be described. FIG. 4 is a flowchart of the control of the first embodiment. First, in step S1, the air amount GAp calculated based on the air amount GAa calculated based on the signal of the air flow meter 51 and the signal of the intake pressure sensor 52 is shown. Is read. Therefore, as a premise, the calculation of the air amount GAa based on the signal of the air flow meter 51 and the calculation of the air amount GAp based on the signal of the intake pressure sensor 52 are always performed.

  In step S2, it is determined whether or not the brake is ON, that is, whether or not the brake pedal 150 is depressed. This is based on a signal from the brake switch 53. If an affirmative determination is made in step S2, the process proceeds to step S4. If a negative determination is made, the process proceeds to step S3.

On the other hand, when the process proceeds to step S3, the brake is turned off, that is, the brake pedal 150 is not depressed, but whether or not a predetermined time has elapsed since the brake was turned on from the brake on, Determine. This predetermined time is set to a slightly larger value based on the time until the inside of the brake booster 100 changes from the state shown in FIG. 3B to the state shown in FIG.
If a negative determination is made in step S3, the process proceeds to step S4. If an affirmative determination is made in step S3, the process proceeds to step S5.

  In step S4, the air amount GAp calculated based on the signal of the intake pressure sensor 52 is ended as the air amount GA used for the subsequent various controls. In step S5, the air amount GAa calculated based on the signal from the air flow meter 51 is ended as the air amount GA used for the subsequent various controls.

  The air amount GAp calculated based on the signal from the intake pressure sensor 52 is acted as described above, and when the brake is ON and when a predetermined time has not elapsed since the brake was turned ON. The air amount GAa calculated based on the signal from the air flow meter 51 is used for subsequent control, and when the brake is OFF (however, after a predetermined time has elapsed since the brake was turned OFF after the brake was turned ON) Used for control.

  Since the intake pressure sensor 52 is disposed on the downstream side of the negative pressure intake portion 11a, the air amount GAp calculated based on the signal of the intake pressure sensor 52 includes the amount of air flowing in from the brake booster 100. By using this value, the amount of air actually sucked matches the amount of air used for control. Therefore, the air-fuel ratio control and the like can be correctly performed when the brake is on and when a predetermined time has not elapsed since the brake was turned on after the brake was turned on.

In the above-described embodiment, the air amount GAa calculated based on the signal from the air flow meter 51 is normally used for the subsequent control, and is predetermined when the brake is turned on and after the brake is turned on. When the time has not elapsed, the air amount GAp calculated based on the signal from the intake pressure sensor 52 is used for the subsequent control.
This is based on the premise that the air amount GAa calculated based on the signal from the air flow meter 51 is the same as the air amount GAp calculated based on the signal from the intake pressure sensor 52.

  However, they are not necessarily the same. Therefore, in the second embodiment described below, the value of the air amount GAa calculated based on the signal of the air flow meter 51 is used in an overwhelmingly large proportion, so that the signal of the intake pressure sensor 52 is used. The value of the air amount GAp calculated based on the correction is corrected so as to become the air amount GAa calculated based on the signal of the air flow meter 51.

FIG. 5 shows a flowchart of the second embodiment. Compared to the first embodiment, steps S1, S2, S3, S4, and S5 are the same as those in the first embodiment. However, the difference is that step SA and step SB are performed before step S4 when an affirmative determination is made at step S2 and when a negative determination is made at step S3.
In step SA, the correction coefficient K for correcting the air amount GAp calculated based on the signal of the intake pressure sensor 52 as described above to be the air amount GAa calculated based on the signal of the air flow meter 51 is calculated. In step SB, GAp is replaced with K × GAp.

FIG. 6 is a flowchart of a subroutine for calculating the correction coefficient K in the above step SA.
The idea is that the value obtained by dividing GAa by GAp is K, but when the brake is on and when a predetermined time has not elapsed since the brake was turned on, the two values are different. Therefore, the value at the time of brake OFF (however, after a predetermined time elapses after the brake is turned off from the brake ON) is adopted. This value is temporarily stored. The stored K value is used when the brake is turned on and when a predetermined time has not elapsed since the brake was turned on after the brake was turned on. The newly calculated value is used after a predetermined time has elapsed.

  Therefore, in step SA1, it is determined whether or not the brake is ON, that is, whether or not the brake pedal 150 is depressed. If an affirmative determination is made in step SA1, the process proceeds to step SA6, and if a negative determination is made, the process proceeds to step SA2. In step SA2, it is determined whether or not a predetermined time has elapsed since the brake was turned on from the brake on. If the determination is affirmative, the process proceeds to step SA3. If the determination is negative, the process proceeds to step SA6. . In step SA3, a value obtained by dividing the current GAa by GAp is set as a new K value Knew. In step SA4, the correction coefficient K used in the main routine is set to Knew. In step SA5, Kold stored for the next time is updated with K set to Knew in step SA4. In step SA6, the correction coefficient K used in the main routine is stored as Kold.

  The present invention includes a constant pressure chamber that is communicated with a negative pressure intake portion of a suction pipe and in which suction pipe negative pressure always acts, a variable pressure chamber that is disposed adjacent to the constant pressure chamber, and a constant pressure chamber and a variable pressure chamber that are communicated when the brake pedal is not depressed. When the brake pedal is depressed, the communication between the constant pressure chamber and the variable pressure chamber is blocked and the atmosphere is introduced into the variable pressure chamber. When the brake pedal is depressed, the atmosphere flows into the constant pressure chamber. The present invention can be applied to an internal combustion engine including a brake booster having a differential pressure switching mechanism.

It is a figure which shows the whole hardware constitutions of embodiment of this invention. It is a figure which shows the structure of an example of a brake booster. It is a figure explaining the action | operation of the communication state switching mechanism of the brake booster of FIG. 2, Comprising: (A) It is a figure which shows the state at the time of brake OFF. (B) It is a figure explaining the state at the time of brake ON. (C) It is a figure which shows the state at the time of the transition from brake ON to brake OFF. It is a flowchart of a 1st embodiment. It is a flowchart of a 2nd embodiment. It is a flowchart of the subroutine for calculation of the correction coefficient in 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine 51 ... Air flow meter 52 ... Intake pressure sensor 53 ... Brake switch 100 ... Brake booster 110 ... Constant pressure chamber 120 ... Transformer chamber 130 ... Brake master cylinder 140 ... Communication state switching mechanism 142 ... Valve plunger 146 ... Poppet valve 147 ... 1st communication path 148 ... 2nd communication path

Claims (5)

An internal combustion engine for a vehicle, comprising a brake booster,
The brake booster communicates with the negative pressure intake part of the suction pipe, the constant pressure chamber where the negative pressure of the suction pipe always acts, the variable pressure chamber arranged adjacent to the constant pressure chamber, and the constant pressure chamber and the variable pressure chamber when the brake is OFF. This shuts off the introduction of atmospheric pressure into the transformer room, shuts off the communication between the constant pressure chamber and the transformer room when the brake is on, and introduces air into the transformer room. When the brake turns on and off, the air flows from the transformer room to the constant pressure chamber. And having a differential pressure switching mechanism,
First intake air amount detection means for detecting the intake air amount upstream of the negative pressure intake portion;
A second intake air amount detection means for detecting an intake air amount downstream of the negative pressure intake portion;
Brake on / off judging means for judging whether the brake is on or off,
Comprising
When the brake is OFF and a predetermined time has elapsed after the brake is turned ON, the air amount is calculated based on the detection value of the first intake air amount detection means,
When the brake is ON and when the predetermined time has not elapsed after the brake is turned ON → OFF, the air amount is calculated based on the detection value of the second intake air amount detection means.
An internal combustion engine characterized by that.   One of the first intake air amount detection means and the second intake air amount detection means is an intake air flow rate detection means for detecting the intake air flow rate, and the other is an intake air pressure detection means for detecting the intake air pressure. The internal combustion engine according to claim 1.   The air amount is calculated based on the detection values detected simultaneously by the intake air pressure detection means and the intake air flow rate detection means, and the air amount calculated based on the detection value of the intake air pressure detection means is used as the detection value of the intake air flow rate detection means. The internal combustion engine according to claim 2, further comprising a correction unit that corrects the air amount so as to be the same as the amount of air that has been originally calculated.   The air amount is simultaneously detected by the intake air pressure detecting means and the intake air flow rate detecting means when the brake is OFF and a predetermined time has elapsed after the brake is turned ON. Internal combustion engine.   2. The internal combustion engine according to claim 1, wherein the air quantity is always detected by both the first intake air quantity detection means and the second intake air quantity detection means.

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