JP3489368B2 - Negative pressure control device for internal combustion engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative pressure control device for an internal combustion engine, and more particularly to a negative pressure control device for an internal combustion engine including a brake booster that secures a braking force based on negative pressure. is there.

[0002]

2. Description of the Related Art Conventionally, in a generally used engine, fuel from a fuel injection valve is injected into an intake port, and a homogeneous mixture of fuel and air is previously supplied to a combustion chamber. In such an engine, an intake passage is opened / closed by a throttle valve that operates in conjunction with accelerator operation, and this opening / closing causes an amount of intake air supplied to a combustion chamber of the engine (as a result, a gas in which fuel and air are homogeneously mixed) The quantity) is adjusted and thus the engine output is controlled.

However, in the above-mentioned technique based on so-called homogeneous combustion, a large intake negative pressure is generated along with the throttle operation of the throttle valve, resulting in a large pumping loss and a low efficiency. On the other hand, by reducing the throttle of the throttle valve and supplying fuel directly to the combustion chamber, a combustible air-fuel mixture is present in the vicinity of the spark plug, and the air-fuel ratio of that portion is increased,
There is known a so-called "stratified combustion" technique for improving ignitability.

For example, in the technique disclosed in Japanese Unexamined Patent Publication No. 8-164840, a fuel injection valve for homogeneous combustion for uniformly injecting and supplying the fuel into the combustion chamber, and a fuel for the periphery of the ignition plug. And a fuel injection valve for stratified combustion that directly supplies the fuel. Then, when the engine load is low, fuel is injected from the fuel injection valve for stratified charge combustion, is unevenly distributed around the spark plug, and the throttle valve is opened to perform stratified charge combustion. As a result, the pumping loss can be reduced and the fuel consumption can be improved.

Further, in this technique, the braking force is increased,
It is equipped with a brake booster to reduce the depression force of the brake pedal. As a power source of the brake booster, negative pressure generated in the intake pipe downstream of the throttle valve is used. That is, the negative pressure is guided to the brake booster via the pressure guiding pipe branched from the downstream side of the throttle valve. Then, the negative pressure corresponding to the depression amount of the brake pedal acts on the diaphragm built in the brake booster, so that the brake operating force is increased.

However, in an engine capable of performing such stratified charge combustion, during the stratified charge combustion, the degree of negative pressure in the intake pipe becomes small, and the negative pressure for operating the brake booster may be insufficient.

Therefore, according to the technique disclosed in the above publication, when the brake booster negative pressure is insufficient, the throttle valve is forcibly closed to generate the intake pipe negative pressure, and thus the negative pressure for braking. I try to secure the pressure.

[0008]

However, in the above technique, the pressure acting on the brake booster is detected as an absolute pressure by the pressure sensor provided in the connecting pipe communicating with the brake booster, and the detected pressure is When the pressure was higher than the reference pressure, it was determined that the degree of negative pressure was low (negative pressure was insufficient).

On the other hand, when the negative pressure in the brake booster is suddenly reduced, such as when the driver suddenly depresses the brake pedal, it is necessary to generate the negative pressure early. That is, in the above technique, it is necessary to secure the negative pressure even before the detected pressure becomes equal to or higher than the reference pressure.

The present invention has been made to solve the above problems, and an object thereof is to determine the degree of brake operation in an internal combustion engine equipped with a brake booster that secures a braking force based on negative pressure. Accordingly, it is an object of the present invention to provide a negative pressure control device for an internal combustion engine that can sufficiently secure the negative pressure required for operating the brake booster.

[0011]

In order to achieve the above object, according to the invention described in claim 1, as shown in FIG. 1, based on the negative pressure acting on itself, based on the rotation of the internal combustion engine M1, Brake booster M3 for securing the braking force of vehicle M2 that can travel, and said brake booster M3
Negative pressure acting means M4 for applying negative pressure to the negative pressure, negative pressure recognizing means M5 for recognizing the amount of negative pressure acting in the brake booster M3, and negative pressure decrease change recognized by the negative pressure recognizing means M5. The gist is that it is provided with negative pressure control means M6 for controlling the negative pressure acting means M4 to apply a negative pressure to the brake booster M3 when the amount is larger than a predetermined amount.

Further, in the invention described in claim 2,
A brake booster for securing a braking force of a vehicle that can travel based on the rotation of the internal combustion engine based on the negative pressure acting on the self, negative pressure acting means for exerting a negative pressure on the brake booster, and the brake booster. Negative pressure recognition means for recognizing the amount of negative pressure acting inside, and when the negative pressure recognized by the negative pressure recognition means is less than the reference value,
A negative pressure control device for an internal combustion engine, comprising: a first negative pressure control means for controlling the negative pressure acting means to exert a negative pressure on the brake booster; and a negative pressure recognized by the negative pressure recognizing means. The gist of the present invention is to provide second negative pressure control means for controlling the negative pressure acting means to exert a negative pressure on the brake booster when the amount of decrease in pressure change is larger than a predetermined amount. .

Furthermore, in the invention according to claim 3, in the negative pressure control apparatus for an internal combustion engine according to claim 1, wherein the negative pressure control hand stage, reduction of the negative pressure that is recognized by the negative pressure recognition means The gist of the invention is to make the control amount of the negative pressure acting means variable according to the change amount. Also, the contract
In the invention described in claim 4, the internal combustion engine according to claim 2
In the negative pressure control device, the second negative pressure control means is
The negative pressure is recognized by the negative pressure recognizing means, and
On the other hand, the control amount of the negative pressure acting means is made variable.
That is the gist. In addition, according to claim 5,
In the invention, negative pressure control of an internal combustion engine according to claim 1 or 3
In the device, the internal combustion engine can perform stratified combustion.
And the control by the negative pressure control means is stratified
That what can be done when combustion is taking place
The summary is. In the invention according to claim 6,
Is the negative pressure control device for an internal combustion engine according to claim 2 or 4.
The internal combustion engine is capable of performing stratified combustion.
And the control by the second negative pressure control means is
That what can be done when combustion is taking place
The summary is.

In addition, in the invention described in claim 7 , in the negative pressure control device for an internal combustion engine according to any one of claims 1 to 6 , the negative pressure recognition means is detected by an atmospheric pressure detection sensor. The gist of the invention is to recognize the negative pressure acting in the brake booster based on the difference between the atmospheric pressure and the pressure introduced into the brake booster detected by the pressure detection sensor.

In addition, in the invention described in claim 8 , in the negative pressure control device for an internal combustion engine according to any one of claims 1 to 7 , the negative pressure acting means is a negative pressure introduced into the brake booster. The gist of the invention is to have a negative pressure generating means for generating a pressure in the intake passage of the internal combustion engine.

Further, in the invention described in claim 9 ,
The gist of the negative pressure control device for an internal combustion engine according to Item 8 is that the negative pressure generating means generates a negative pressure by narrowing an opening area of the intake passage.

Further, in the invention according to claim 10 , in the negative pressure control device for an internal combustion engine according to claim 8 or 9 , the negative pressure generating means is a throttle valve provided in the intake passage and the throttle valve. Electronically controlled throttle mechanism including an actuator for opening and closing a valve, an idle speed control valve provided in a bypass intake passage bypassing a throttle valve provided in an intake passage, and an ISC mechanism including an actuator for opening and closing the valve And an exhaust gas recirculation passage that connects the exhaust passage and the intake passage of the internal combustion engine, and an EGR valve for opening and closing the exhaust gas recirculation passage, and a part of the exhaust gas discharged from the internal combustion engine By at least one of the EGR mechanisms for recirculating the exhaust gas to the intake air taken into the internal combustion engine. That it is configured that the gist thereof.

[0018]

(Operation) According to the invention described in claim 1,
As shown in FIG. 1, the vehicle M2 can travel based on the rotation of the internal combustion engine M1. Further, the braking force of the vehicle M2 is secured based on the negative pressure acting on the brake booster M3.
A negative pressure is applied to the brake booster M3 by the negative pressure applying means M4.

In the present invention, the amount of negative pressure acting in the brake booster M3 is recognized by the negative pressure recognizing means M5. When the decrease amount of the negative pressure recognized by the negative pressure recognizing means M5 is larger than the predetermined amount, the negative pressure control means M6 controls the negative pressure acting means M4,
A negative pressure is applied to the brake booster M3.

Therefore, for example, by sudden braking,
Even if the negative pressure in the brake booster M3 suddenly decreases, the negative pressure is secured relatively early.

According to the second aspect of the invention, when the negative pressure recognized by the negative pressure recognizing means is less than the reference value, the first negative pressure control means operates the negative pressure. The means are controlled and a negative pressure is applied to the brake booster. Further, even when the amount of decrease in the negative pressure recognized by the negative pressure recognizing means is larger than the predetermined amount, the second negative pressure control means controls the negative pressure acting means, and the negative pressure acts on the brake booster. To be made.

Therefore, in addition to the operation of the invention described in claim 1, even when the negative pressure is lower than the reference value, the negative pressure acts on the brake booster by the first negative pressure control means. Will be made. Therefore, it becomes possible to more surely eliminate the lack of negative pressure.

Further, according to the invention of claim 3,
In addition to the action of the invention described in claim 1, the negative pressure control hand
Thus the stage, the control amount of the negative pressure application means in accordance with a decrease the amount of change in the negative pressure that is recognized by the negative pressure recognition means is variable. According to the invention of claim 4,
In addition to the operation of the invention described in 2, the second negative pressure control hand
The negative pressure of the negative pressure recognized by the negative pressure recognition means by the step.
The control amount of the negative pressure acting means is variable according to the decreasing change amount.
To be done. Therefore, when the amount of decrease in negative pressure is large,
More negative pressure will be secured. In addition, request
According to the invention of claim 5, the invention of claim 1 or 3
In addition to the function of light, the internal combustion engine performs stratified combustion.
The control by the negative pressure control means is
It can be done when stratified combustion is taking place. Also bill
According to the invention of claim 6, the invention according to claim 2 or 4
In addition to the function of light, the internal combustion engine performs stratified combustion.
And is controlled by the second negative pressure control means.
The control can be performed while the stratified charge combustion is being performed. here
When the stratified charge combustion is being executed,
Is large, the degree of negative pressure in the intake passage
It will be relatively small. Therefore, according to the present invention,
If the negative pressure tends to be small,
It is possible to ensure the negative pressure.

In addition, according to the invention of claim 7 ,
In addition to the operation of the invention described in claims 1 to 6 , in the negative pressure recognition means, the atmospheric pressure detected by the atmospheric pressure detection sensor and the pressure introduced into the brake booster detected by the pressure detection sensor. The negative pressure acting in the brake booster is recognized on the basis of the difference between and. Therefore, for example, when the vehicle is traveling in a high altitude, the pressure introduced into the brake booster detected by the pressure detection sensor is relatively low, but it is actually necessary to operate the brake booster. There may be cases where the negative pressure is insufficient. However, according to the present invention, since the negative pressure recognized by the negative pressure recognizing means is a relative pressure, the negative pressure is surely secured when it is necessary to secure the negative pressure.

In addition, according to the invention described in claim 8 ,
In addition to the operation of the invention described in claims 1 to 7 , the negative pressure acting means has a negative pressure generating means, and by this negative pressure generating means, a negative pressure is generated in the intake passage of the internal combustion engine. The generated negative pressure is introduced into the brake booster.

According to the invention of claim 9 , in addition to the operation of the invention of claim 8 , the negative pressure generating means generates a negative pressure by narrowing the opening area of the intake passage. It is what makes me. Therefore, it is possible to generate a negative pressure using an existing device that can narrow the opening area of the intake passage.

Further, according to the invention described in claim 10 , in addition to the operation of the invention described in claims 8 and 9 , the negative pressure generating means includes a throttle valve provided in the intake passage and the throttle valve. Electronically controlled throttle mechanism including an actuator for opening and closing a valve, an idle speed control valve provided in a bypass intake passage bypassing a throttle valve provided in an intake passage, and an ISC mechanism including an actuator for opening and closing the valve And an exhaust gas recirculation passage that connects the exhaust passage and the intake passage of the internal combustion engine, and an EGR valve for opening and closing the exhaust gas recirculation passage, and a part of the exhaust gas discharged from the internal combustion engine At least one of the EGR mechanisms for recirculating the engine to intake air taken into the internal combustion engine. To have. Therefore, the above claims
The effects of the inventions described in 8 and 9 are more reliably exhibited.

[0029]

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a negative pressure control device for an internal combustion engine according to the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a schematic configuration diagram showing a negative pressure control device for a direct injection engine mounted on a vehicle in the present embodiment. The engine 1 includes, for example, four cylinders 1a, and the combustion chamber structure of each cylinder 1a is shown in FIG. As shown in these figures, the engine 1 includes a piston in a cylinder block 2, and the piston reciprocates in the cylinder block 2. A cylinder head 4 is provided above the cylinder block 2, and a combustion chamber 5 is formed between the piston and the cylinder head 4. Further, in the present embodiment, four valves are arranged per cylinder 1a. In the figure, reference numeral 6a designates a first intake valve, 6b designates a second intake valve, 7a designates a first intake port, and 7b designates a first intake port. 2 intake ports, 8 a pair of exhaust valves, and 9 a pair of exhaust ports.

As shown in FIG. 3, the first intake port 7a
Is a helical intake port, and the second intake port 7
b consists of a straight port that extends almost straight.
An ignition plug 10 is arranged at the center of the inner wall surface of the cylinder head 4. In this spark plug 10,
Igniter 12 via a distributor (not shown)
The high voltage from is applied. And
The ignition timing of the spark plug 10 is set to the igniter 1
2 is determined by the output timing of the high voltage. Further, a fuel injection valve 11 is arranged near the inner wall surface of the cylinder head 4 near the first intake valve 6a and the second intake valve 6b. That is, in the present embodiment, the fuel from the fuel injection valve 11 is directly injected into the cylinder 1a, and so-called stratified combustion and homogeneous combustion are performed.

As shown in FIG. 2, the first intake port 7a and the second intake port 7b of each cylinder 1a are routed through a first intake passage 15a and a second intake passage 15b formed in the intake manifold 15, respectively. Connected to the surge tank 16. A swirl control valve 17 is arranged in each second intake passage 15b. These swirl control valves 17 are connected to a step motor 19, for example, via a common shaft 18. The step motor 19 is controlled based on an output signal from an electronic control unit (hereinafter simply referred to as “ECU”) 30 described later. Instead of the step motor 19, a motor that is controlled according to the negative pressure of the intake ports 7a and 7b of the engine 1 may be used.

The surge tank 16 has an intake duct 20.
Is connected to the air cleaner 21 via the
A throttle valve 23, which constitutes negative pressure acting means (negative pressure generating means) that is opened and closed by the step motor 22, is provided therein. That is, the throttle valve 23 of the present embodiment is of a so-called electronically controlled type, and basically, the step motor 22 as an actuator which also constitutes negative pressure acting means is based on the output signal from the ECU 30. When driven, the throttle valve 23
Is controlled to open and close. By opening / closing the throttle valve 23, the amount of intake air introduced into the combustion chamber 5 through the intake duct 20 is adjusted, and the negative pressure generated in the intake duct 20 is adjusted. It is supposed to be adjusted. In the present embodiment, the intake duct 20, the surge tank 16, the first intake passage 15a, the second intake passage 15b, and the like form an intake passage.

A throttle sensor 25 for detecting the opening (throttle opening TA) is provided near the throttle valve 23. An exhaust manifold 14 is connected to the exhaust port 9 of each cylinder.
Then, the exhaust gas after combustion is discharged to an exhaust pipe (not shown) through the exhaust manifold 14.

Further, in this embodiment, a known exhaust gas recirculation (EGR) mechanism 51 is provided. This E
The GR mechanism 51 includes an EGR passage 52 as an exhaust gas recirculation passage, and an EGR valve 53 provided in the passage 52. The EGR passage 52 is provided so as to connect the intake duct 20 downstream of the throttle valve 23 and the exhaust duct. In addition, the EGR valve 53
Incorporates a valve seat, a valve body, and a step motor (all not shown). The opening degree of the EGR valve 53 fluctuates as the step motor intermittently displaces the valve body with respect to the valve seat. Then, when the EGR valve 53 is opened, a part of the exhaust gas discharged to the exhaust duct flows into the EGR passage 52. The exhaust gas flows into the intake duct 20 via the EGR valve 53. That is,
A part of the exhaust gas is recirculated into the intake mixture by the EGR mechanism 51. At this time, the recirculation amount of the exhaust gas is adjusted by adjusting the opening degree of the EGR valve 53.

Further, as shown in FIGS. 2 and 4, in the present embodiment, a brake booster 71 is provided as a device for ensuring the braking force of the vehicle. By this brake booster 71, the depression force of the brake pedal 72 is amplified and converted into hydraulic pressure, and the brake actuator (not shown) of each wheel is driven. The brake booster 71 is connected to the intake duct 20 on the downstream side of the throttle valve 23 via a connection pipe 73, and is configured to use the negative pressure generated in the duct 20 as a driving force. ing. Further, the connection pipe 73 is provided with a check valve 74 that opens in the intake duct 20 by negative pressure. That is, the brake booster 71 has a diaphragm inside. And
One side of the diaphragm is open to the atmosphere, and the negative pressure generated in the duct 20 is applied to the other side of the connecting pipe 7
It is designed to work through 3. Further, the connection pipe 73 is provided with a pressure sensor 63 as a pressure detection sensor for detecting the brake booster internal pressure PBK (absolute pressure).

The ECU 30 described above is composed of a digital computer, and is connected to each other via the bidirectional bus 31 RAM (random access memory) 3
2, a ROM (Read Only Memory) 33, a CPU (Central Processing Unit) 34 including a microprocessor, an input port 35 and an output port 36. In the present embodiment, the ECU 30 constitutes negative pressure recognition means and negative pressure control means.

An accelerator sensor 26A for generating an output voltage proportional to the amount of depression of the accelerator pedal 24 is connected to the accelerator pedal 24, and the accelerator sensor 2 is connected to the accelerator sensor 26A.
The accelerator opening ACCP is detected by 6A. The output voltage of the accelerator sensor 26A is input to the input port 35 via the AD converter 37. Similarly, the accelerator pedal 24 has a fully closed switch 26B for detecting that the depression amount of the accelerator pedal 24 is "0".
Is provided. That is, this fully closed switch 26B
Generates a signal of "1" as the fully closed signal XIDL when the depression amount of the accelerator pedal 24 is "0", and otherwise generates a signal of "0". The output voltage of the fully closed switch 26B is also input to the input port 35.

The top dead center sensor 27 generates an output pulse when the first cylinder 1a reaches the intake top dead center, for example.
This output pulse is input to the input port 35. The crank angle sensor 28 has, for example, a crankshaft of 30 ° CA.
An output pulse is generated each time it rotates, and this output pulse is input to the input port. In the CPU 34, the top dead center sensor 2
The engine speed NE is calculated (read) from the output pulse of 7 and the output pulse of the crank angle sensor 28.

Further, the rotation angle of the shaft 18 is detected by a swirl control valve sensor 29,
Thereby, the opening degree of the swirl control valve 17 is measured. Then, the output of the swirl control valve sensor 29 is sent to the input port 35 via the A / D converter 37.
Entered in.

At the same time, the throttle opening 25 is detected by the throttle sensor 25. The output of the throttle sensor 25 is input to the input port 35 via the A / D converter 37.

In addition, in the present embodiment, an intake pressure sensor 61 for detecting the pressure in the surge tank 16 (intake pressure PiM) is provided. However, when the engine 1 is started, the intake pressure P detected by the intake pressure sensor 61 is
Since it is apparent that iM is almost equal to the atmospheric pressure PA, in the present embodiment, the description will be given below assuming that the atmospheric pressure PA is also detected by the intake pressure sensor 61.
That is, in the present embodiment, the intake pressure sensor 61 constitutes an atmospheric pressure detection sensor.

Further, in the present embodiment, a water temperature sensor 62 for detecting the temperature of the cooling water of the engine 1 (cooling water temperature THW) is provided. In addition, the vehicle speed (vehicle speed) S
A vehicle speed sensor 64 for detecting the PD is also provided. The outputs of these sensors 61, 62, 64 are also input to the input port 35 via the A / D converter 37. The output of the pressure sensor 63 is also input to the input port 35 via the A / D converter 37.

In the present embodiment, these throttle sensor 25, accelerator sensor 26A, fully closed switch 26
B, top dead center sensor 27, crank angle sensor 28, swirl control valve sensor 29, intake pressure sensor 61,
The operating state of the engine 1 is detected by the water temperature sensor 62, the pressure sensor 63, the vehicle speed sensor 64, and the like.

On the other hand, the output port 36 is connected to each fuel injection valve 11 and each step motor 1 via the corresponding drive circuit 38.
9, 22, the igniter 12, and the EGR valve 53 (step motor) are connected. Then, the ECU 30 follows the control program stored in the ROM 33 based on the signals from the respective sensors 25 to 29, 61 to 64,
The fuel injection valve 11, the step motors 19 and 22, the igniter 12 (ignition plug 10), the EGR valve 53, etc. are suitably controlled.

Next, a program relating to various controls according to the present embodiment in the negative pressure control device for the engine 1 having the above-mentioned configuration will be described with reference to a flowchart and the like. That is, FIGS. 5 and 6 are flowcharts showing a “negative pressure control routine” for controlling the throttle valve 23 (step motor 22) in the present embodiment to control the negative pressure introduced into the brake booster 71. However, the ECU 30 executes the operation on the assumption that the operation in the stratified charge combustion is currently being executed.

When the processing shifts to this routine, the ECU
First, in step 101, 30 is from atmospheric pressure PA,
A value obtained by subtracting the latest brake booster internal pressure PBK currently detected by the pressure sensor 63 is set as the brake booster internal relative pressure DPBK.

Next, at step 102, the vehicle speed SPD read this time is a predetermined speed (for example, "20 km /
h ”). And vehicle speed SP
If D is greater than the predetermined speed, the process proceeds to step 103.

In step 103, the current operating state of the engine 1 is a steady state (for example, the state in which the engine speed NE has become stable after the airbag 1 has warmed up, or
The engine 1 is not in acceleration / deceleration), and
The relative pressure DPBK in the brake booster is equal to a predetermined stratified brake control start negative pressure amount tKPBKL (for example, "3.
00 mmHg "). If any of the above conditions is not satisfied, the control for ensuring the brake negative pressure is not performed, and the subsequent process is temporarily terminated.

On the other hand, when the operating state of the engine 1 is in a steady state and the brake booster relative pressure DPBK is smaller than the stratified brake control start negative pressure amount tKPBKL, it is necessary to secure the brake negative pressure. Then, the process proceeds to step 104.

In step 104, the ECU 30
The closing control of the throttle valve 23 is executed. More specifically, the ECU 30 reduces the opening degree of the throttle valve 23 within a range that does not hinder traveling, and forcibly generates a negative pressure downstream of the throttle valve 23.

Further, in the following step 105, again, the latest brake booster internal pressure PBK currently detected by the pressure sensor 63 is subtracted from the atmospheric pressure PA,
The value is set as the relative pressure DPBK in the brake booster.

Then, in step 106, it is determined whether or not the latest relative brake booster relative pressure DPBK exceeds a predetermined negative pressure amount tKPBKO for ending stratification brake control (eg, "350 mmHg").
Then, when the relative pressure DPBK in the brake booster does not exceed the stratified brake control end negative pressure amount tKPBKO, the process proceeds to step 104 described above. Then, steps 104 and 10 are performed until the relative pressure DPBK in the brake booster exceeds the stratified brake control end negative pressure amount tKPBKO.
The process of 5, that is, the closing control of the throttle valve 23 is executed.

Further, in step 106, when the relative pressure DPBK in the brake booster exceeds the stratified brake control end negative pressure amount tKPBKO, it is assumed that the necessary negative pressure has been sufficiently secured, and the throttle valve 23 Subsequent processing is once ended to end the closing control.

On the other hand, in step 102, the vehicle speed SPD read this time is set to a predetermined speed (for example, "20 km /
If it is less than h ”), the process proceeds to step 107. At step 107, the fully closed signal XIDL from the fully closed switch 26B is "1" (the depression amount of the accelerator pedal 24 is "0"), and the operating state of the engine 1 is currently in a steady state. Moreover, the relative pressure DPBK in the brake booster is the negative pressure amount tKP for starting the stratified brake control.
It is determined whether it is smaller than BKL. When all the above conditions are satisfied, the process proceeds to step 108.

At step 108, the ECU 30
The throttle valve 23 is closed and the idle control is executed. More specifically, the ECU 30 throttles the opening degree of the throttle valve 23 to an extent necessary for idling,
A negative pressure is forcibly generated downstream of the throttle valve 23.

Further, in the following step 109, again, the latest brake booster internal pressure PBK currently detected by the pressure sensor 63 is subtracted from the atmospheric pressure PA,
The value is set as the relative pressure DPBK in the brake booster.

Then, in step 110, it is determined whether or not the latest relative brake booster relative pressure DPBK exceeds a predetermined stratified brake control end negative pressure amount tKPBKO (for example, "350 mmHg").
Here, when the relative pressure DPBK in the brake booster does not exceed the stratified brake control end negative pressure amount tKPBKO, the process proceeds to step 108 described above. Then, steps 108 and 10 are performed until the relative pressure DPBK in the brake booster exceeds the negative pressure amount tKPBKO at the end of stratified brake control.
The process of No. 9, that is, the idle control by closing the throttle valve 23 is executed.

Further, in step 110, when the relative pressure DPBK in the brake booster exceeds the stratified brake control end negative pressure amount tKPBKO, it is assumed that the necessary negative pressure has been sufficiently secured, and the throttle valve 23 Subsequent processing is once ended in order to end the idle control by closing.

If any one of the conditions is not satisfied in step 107, the process proceeds to step 111 (see FIG. 6). In step 111, the previous relative pressure in the brake booster DPBK _i-1
Relative pressure in brake booster DPBK calculated this time from
_i is subtracted, and the value is set as the negative pressure difference ΔPB.

Further, in the following step 112, it is determined whether or not the negative pressure difference ΔPB is larger than a predetermined amount α. Then, the negative pressure difference ΔPB is a predetermined amount α.
If it is not larger than the above, the subsequent processing is temporarily terminated without performing any processing. On the other hand, the negative pressure difference Δ
When PB is larger than the predetermined amount α, the brake is operated, the negative pressure is rapidly reduced, and it is determined that the negative pressure is insufficient, and the routine proceeds to step 113.

In step 113, the throttle valve 23 is suddenly closed (regardless of whether the relative pressure DPBK in the brake booster is smaller than the stratified brake control start negative pressure amount tKPBKL (a level equivalent to that during idle control). Control so that it closes to. As a result, a negative pressure is forcibly generated downstream of the step valve 23. Then, the ECU 30 once ends the subsequent processing.

Next, the operation and effect of this embodiment will be described. (A) According to the present embodiment, it is judged whether or not it is necessary to secure the negative pressure for the operation of the brake booster 71 (steps 103, 107, etc.), and the result of the judgment is the negative pressure. When it is necessary to ensure the control, the closing control of the opening degree of the throttle valve 23 is executed. Therefore, the amount of negative pressure generated is increased by the closing, and the operation of the brake booster 71 can be ensured.

(B) In the present embodiment, when the negative pressure difference ΔPB is larger than the predetermined amount α regardless of whether the relative pressure DPBK in the brake booster is smaller than the stratified brake control start negative pressure amount tKPBKL. Therefore, it is highly probable that the negative pressure is insufficient, and the throttle valve 23 is controlled to be closed rapidly. Therefore, for example, as shown in FIG. 7, a negative pressure in the brake booster 71 (relative pressure DP in the brake booster) is caused by sudden braking or the like.
Even if BK) suddenly decreases, the negative pressure is secured relatively early.

That is, when the brake pedal is suddenly depressed, the relative pressure DP in the brake booster is suddenly increased.
It will fall to BK. In this case, if nothing is done until it becomes smaller than the stratified brake control start negative pressure amount tKPBKL, the brake booster relative pressure DPBK (negative pressure) tends to become insufficient, as shown by the dashed line in FIG.
On the other hand, in the present embodiment, the closing control of the throttle valve 23 is executed before the negative pressure becomes insufficient,
As shown by the solid line in the figure, the negative pressure can be secured earlier. As a result, it is possible to avoid a problem caused by a lack of negative pressure.

Further, by closing the throttle valve 23, the pumping loss of the engine 1 is increased and the effect of engine braking is also obtained. (C) Further, in the present embodiment, the brake booster 71
In determining whether or not it is necessary to secure a negative pressure for the operation of, the difference between the atmospheric pressure PA and the brake booster internal pressure PBK detected by the pressure sensor 63 (brake booster internal relative pressure DPBK) is calculated. I decided to consider it. Therefore, for example, when the vehicle is traveling in a highland, the atmospheric pressure PA decreases, so that the brake booster internal pressure PBK becomes lower than that in the case of traveling in a lowland. Therefore, although the negative pressure required to operate the brake booster 71 is actually insufficient, the brake booster internal pressure PBK may decrease.
However, according to the present embodiment, not the brake booster internal pressure PBK, but the brake booster internal pressure DPBK.
However, when it is smaller than the stratified brake control start negative pressure amount tKPBKL, the closing control of the throttle valve 23 is executed and the negative pressure is applied. Therefore, even if there is a change in atmospheric pressure PA, such as when traveling in high altitude,
When it is necessary to secure the negative pressure, the negative pressure necessary for the operation of the brake booster can be ensured.

(D) In this embodiment, when the relative pressure DPBK in the brake booster is smaller than the stratified brake control start negative pressure amount tKPBKL, the throttle valve 2
3 is executed, and the closing control is ended when the relative pressure DPBK in the brake booster becomes larger than a reference value (stratified brake control end negative pressure amount tKPBKO) larger than that. I did it. That is, the reference value has hysteresis. Therefore, the relative pressure in the brake booster DPBK
However, it is possible to suppress so-called hunting, in which the closing control is repeatedly performed or not performed by repeating that the value becomes smaller than the reference value or becomes equal to or more than the reference value. As a result, it is possible to prevent the operating state from becoming unstable.

(E) Further, in the present embodiment, as a means for securing the negative pressure, a means for generating the negative pressure by narrowing the opening area of the intake passage, particularly, the throttle valve 23 and the step motor 22 are used. We decided to adopt the electronically controlled throttle mechanism. Therefore, it is possible to generate a negative pressure using an existing device, and eventually it is possible to suppress an increase in cost.

The present invention is not limited to the above embodiment, but may be configured as follows, for example. (1) In the above embodiment, when the negative pressure difference ΔPB is larger than the predetermined amount α, the throttle valve 23 is controlled so as to be closed rapidly. It may be variable according to ΔPB. That is, the closing amount of the throttle valve 23 may be increased as the brake booster internal pressure PBK rapidly increases (the brake booster internal relative pressure DPBK rapidly decreases).

Alternatively, the throttle valve 23 is closed according to how much the present relative pressure DPBK in the brake booster is sufficient for the stratified brake control end negative pressure amount tKPBKO (or how much is insufficient). The amount of inclusion may be variable. By adopting such control, the closing speed increases immediately after the closing control is started, and the negative pressure can be quickly secured. On the contrary, at the stage where the negative pressure is ensured, the closing speed becomes small, and thus the overshoot of the negative pressure generation can be suppressed.

(2) In the above embodiment, the throttle valve 23 provided in the intake duct 20 as the negative pressure acting means (negative pressure generating means) and the step motor as the actuator for opening and closing the throttle valve 23. The throttle valve 23 is composed of an electronically controlled throttle mechanism, but in addition, an idle speed control valve provided in a bypass intake passage bypassing the throttle valve 23 and an ISC mechanism composed of an actuator for opening and closing the valve are constituted. May be.

Further, the E equipped with the EGR valve 53, etc.
You may comprise by the GR mechanism 51. Further, a negative pressure generating mechanism (not shown) may be separately provided. In these cases, a mechanical throttle valve linked to an accelerator pedal 24 may be used instead of the so-called electronically controlled throttle valve 23.

Furthermore, the negative pressure generating means may be constructed by appropriately combining these. (3) In the above embodiment, the present invention is embodied in the cylinder injection type engine 1, but other internal combustion engines of so-called stratified combustion and weak stratified combustion may be used. For example, the intake valves 6a, 6b of the intake ports 7a, 7b
It also includes a type that sprays toward the back side of the umbrella part. Further, although the fuel injection valve is provided on the intake valves 6a and 6b side, a fuel injection valve directly injecting into the cylinder bore (combustion chamber 5) is also included. Alternatively, it may be embodied in an internal combustion engine that does not perform stratified charge combustion.

(4) Further, in the above-described embodiment, the structure is provided with the helical type intake port and the so-called swirl can be generated, but the swirl does not always have to be generated. Therefore, for example, the swirl control valve 17, the step motor 19 and the like in the above embodiment can be omitted.

(5) Further, in the above embodiment, the present invention is embodied in the case of the gasoline engine 1 as the internal combustion engine, but it can be embodied in other cases such as a diesel engine.

(6) In the above embodiment, the atmospheric pressure PA is detected by the intake pressure sensor 61, but an atmospheric pressure sensor may be separately provided to detect the atmospheric pressure.

[0078]

As described in detail above, according to the present invention,
In a negative pressure control device for an internal combustion engine including a brake booster that secures a braking force based on a negative pressure, it is possible to sufficiently secure a negative pressure necessary for operating the brake booster according to the degree of operation of the brake. It has an excellent effect.

[Brief description of drawings]

FIG. 1 is a basic conceptual configuration diagram of the invention described in claim 1.

FIG. 2 is a schematic configuration diagram showing a negative pressure control device for an engine according to an embodiment.

FIG. 3 is an enlarged sectional view showing a cylinder portion of the engine.

FIG. 4 is a configuration diagram showing a brake booster and the like.

FIG. 5 is a "negative pressure control routine" executed by the ECU.
It is a flowchart showing.

FIG. 6 is a "negative pressure control routine" executed by the ECU.
FIG. 6 is a flowchart showing the above, showing the continuation of FIG. 5.

FIG. 7 is a timing chart showing an example of the behavior of relative pressure in the brake booster with the passage of time.

[Explanation of symbols]

1 ... Engine as internal combustion engine, 11 ... Fuel injection valve, 2
0 ... Intake duct, 22 ... Negative pressure acting means (negative pressure generating means)
A step motor constituting 23, a throttle valve constituting a negative pressure acting means (negative pressure generating means), an ECU constituting a negative pressure recognizing means and a negative pressure control means, a suction valve constituting an atmospheric pressure detection sensor, Pressure sensor, 63 ... Pressure sensor as pressure detection sensor, 71 ... Brake booster.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-10-73039 (JP, A) JP-A-11-182278 (JP, A) JP-A-8-164840 (JP, A) JP-A-7- 247866 (JP, A) JP 10-148150 (JP, A) JP 10-151970 (JP, A) JP 10-151971 (JP, A) JP 10-151972 (JP, A) JP-A-10-157606 (JP, A) JP-A-10-167047 (JP, A) JP-A-10-175464 (JP, A) JP-A-10-310049 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B60T 17/00 F02D 9/02 F02D 29/02 341

Claims (10)

(57) [Claims] 1. A brake booster for securing a braking force of a vehicle capable of traveling based on the rotation of an internal combustion engine based on a negative pressure acting on itself, and negative pressure acting means for exerting a negative pressure on the brake booster. Negative pressure recognizing means for recognizing the amount of negative pressure acting in the brake booster, and the negative pressure effect when the amount of decrease in negative pressure recognized by the negative pressure recognizing means is larger than a predetermined amount. Negative pressure control means for controlling the means to apply a negative pressure to the brake booster, and a negative pressure control device for an internal combustion engine. 2. A brake booster for securing a braking force of a vehicle capable of traveling based on the rotation of an internal combustion engine based on a negative pressure acting on itself, and negative pressure acting means for exerting a negative pressure on the brake booster. Negative pressure recognizing means for recognizing the amount of negative pressure acting in the brake booster, and the negative pressure activating means when the negative pressure recognized by the negative pressure recognizing means is less than a reference value. And a first negative pressure control means for controlling the brake booster to apply a negative pressure to the brake booster, further comprising: a negative pressure change amount recognized by the negative pressure recognition means. Negative pressure control means for controlling the negative pressure applying means to apply a negative pressure to the brake booster when the pressure is larger than a predetermined amount. apparatus. Wherein the negative pressure control hand stage, and wherein said that the control amount of the negative pressure recognition means the negative pressure application means in accordance with a decrease the amount of change in the negative pressure that is recognized by those of variable The negative pressure control device for an internal combustion engine according to claim 1 . 4. The second negative pressure control means is configured to recognize the negative pressure.
Depending on the amount of decrease in negative pressure recognized by the recognition means,
It is characterized in that the control amount of the negative pressure acting means is variable.
The negative pressure control device for an internal combustion engine according to claim 2, which is a characteristic . 5. The internal combustion engine can perform stratified combustion.
And the control by the negative pressure control means is stratified
That what can be done when combustion is taking place
The negative pressure control device for an internal combustion engine according to claim 1 or 3 , characterized . 6. The internal combustion engine can perform stratified combustion.
And the control by the second negative pressure control means
Is what can be done while stratified combustion is taking place.
The negative pressure control device for an internal combustion engine according to claim 2, wherein: 7. The negative pressure recognition means is an atmospheric pressure detection sensor.
Detected by the atmospheric pressure and the pressure detection sensor
Difference with the pressure introduced into the brake booster
The negative pressure acting in the brake booster based on
Claims 1 to 6 characterized in that
A negative pressure control device for an internal combustion engine according to any one of the above. 8. The negative pressure acting means is the brake boot.
The negative pressure introduced into the engine into the intake passage of the internal combustion engine.
8. The negative pressure control device for an internal combustion engine according to claim 1 , further comprising negative pressure generating means for generating the negative pressure. 9. The negative pressure generating means is configured to open the intake passage.
Negative pressure is generated by narrowing the mouth area.
9. A negative pressure control for an internal combustion engine according to claim 8, wherein
Your device. 10. The negative pressure generating means is provided in the intake passage.
Opening and closing the provided throttle valve and the throttle valve
Electronically controlled throttle machine consisting of actuators for
By bypassing configuration, the throttle valve disposed in an intake passage
Idle speed controller installed in the path intake passage
Valve and actuator for opening and closing the valve
And an exhaust gas communication unit that connects the exhaust passage and the intake passage of the internal combustion engine.
Open and close the exhaust gas recirculation passage and the exhaust gas recirculation passage.
Having an EGR valve for discharge from the internal combustion engine
Recirculate a part of exhaust gas to intake air taken into the internal combustion engine
By at least one of the EGR mechanisms for
It is comprised, The claim 8 or 9 characterized by the above-mentioned.
Negative pressure control device for internal combustion engine.