JP2983395B2 - Negative intake pressure control system 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 an intake negative pressure control system for an internal combustion engine, and more particularly, to an intake negative pressure control for an internal combustion engine in which the amount of intake air is controlled by the opening degree of a throttle valve and the opening period of the intake valve. Related to the device.

[0002]

2. Description of the Related Art Valve timing (valve opening timing and valve lift amount) of an intake valve provided in an engine cylinder head.
The so-called non-throttling engine that controls the intake air amount by making the intake air amount variable is different from the throttling engine that controls the intake air amount by controlling the opening and closing of a throttle valve provided in the intake passage. Since no pressure is generated and so-called pumping loss is reduced, there is an advantage that fuel efficiency can be improved.

[0003] On the other hand, in the non-throttling engine, since the intake negative pressure is not generated as described above, a negative pressure device such as an exhaust gas recirculation device (EGR device) or an evaporative fuel processing device cannot be used. There is a disadvantage in that it is inconvenient to suppress emission of harmful components such as NOx and evaporated fuel generated in the fuel tank to the atmosphere.

Further, in the above-mentioned non-throttling engine, the promotion of atomization of the liquid fuel is hindered because the intake negative pressure is not generated even in a low load region, which leads to an increase in the amount of fuel adhering to the intake pipe, thereby deteriorating the combustion performance. There was also a disadvantage of doing so.

Therefore, as a means for solving such a disadvantage, in a non-throttle engine, the amount of intake air is controlled by controlling the opening period of the throttle valve and the intake valve.
There has been proposed one that improves combustion at low load and improves control accuracy (for example, Japanese Patent Publication No. 59-22055).

[0006]

However, in the above prior art, since the throttle valve is interlocked with the accelerator pedal, the intake negative pressure fluctuates according to the accelerator opening, so that the negative pressure required for the negative pressure device is reduced. However, there is a problem that it is difficult to always secure the negative pressure and the control of the negative pressure device becomes complicated.

When it is desired to use a brake booster as a negative pressure device, for example, it is conceivable to separately provide an air pump for generating a predetermined negative pressure. However, deterioration of fuel efficiency and cost due to a drive loss of the air pump are considered. However, there is a problem that it is difficult to secure the space on the layout, or to increase the layout.

If it is desired to use an EGR device, the EGR valve can be lifted with a slight negative pressure so that the EGR valve can be lifted.
It is conceivable to increase the diameter of the diaphragm of the GR valve or to increase the size of the EGR valve in order to secure the recirculation amount. However, problems such as deterioration of the recirculation amount control and increase in the weight of the entire apparatus occur.

The present invention has been made in view of the above problems, and provides an intake negative pressure control device for an internal combustion engine that can utilize a negative pressure device while ensuring low fuel consumption even in a non-throttle engine. The purpose is to:

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an intake valve whose opening period can be arbitrarily changed, an electrically operated throttle valve, and a driving force for negative pressure in an intake pipe. A negative pressure control device for an internal combustion engine having a control device as a source, a pressure accumulating means for accumulating a negative pressure in an intake pipe, a pressure detecting means for detecting a pressure of the pressure accumulating means, and detecting an operating state of the engine. Operating state detecting means, and operating area determining means for determining, based on a detection result of the operating state detecting means, whether or not the operating area is in an operating area in which the intake air amount is controlled only by the intake valve; Even when it is determined by the determining means that the operation is in the operating range in which the intake air amount is controlled only by the intake valve, if the pressure detected by the pressure detecting means is equal to or less than a predetermined value, the intake valve and the throttle valve are stopped. The torque valve is characterized by having an intake negative pressure generating means for generating a negative pressure in the intake pipe. Further, the control device is specifically a vehicle brake booster.

Further, the present invention has an intake valve whose opening period can be arbitrarily changed, an electrically operated throttle valve, and a control device for controlling a control gas introduced by a negative pressure in the intake pipe. In an intake negative pressure control device for an internal combustion engine, an operating state detecting means for detecting an operating state of the engine and an operating state detecting means for detecting whether or not the engine is in an operating area in which the intake air amount is controlled only by the intake valve. Operating region discriminating means for discriminating based on a result, even if it is determined that the operating region discriminating device is in an operating region in which the intake air amount is controlled only by the intake valve, at least the control device When a specific operation state in which the control gas is to be introduced is provided, there is provided an intake negative pressure setting means for setting the inside of the intake pipe to a predetermined negative pressure by the intake valve and the throttle valve. It is set to.

The control device includes a fuel tank, a canister for adsorbing and storing fuel vapor generated from the fuel tank, a purge passage connecting the canister to an intake system of an internal combustion engine, It is characterized by being an evaporative fuel treatment device having a purge control valve interposed in the purge passage and / or an exhaust gas recirculation device for recirculating a part of exhaust gas to an intake pipe.

[0013]

According to the above construction, when the pressure of the pressure accumulating means is equal to or less than the predetermined value, the intake valve and the throttle valve generate an intake negative pressure. Thus, the vehicle brake booster using the negative pressure in the intake pipe as a driving force source can always be operated.

Further, according to the above configuration, in the specific operation state in which the control gas is to be introduced into the control device, the intake pipe and the throttle valve are set to a predetermined negative pressure in the intake pipe. Thereby, the evaporative fuel processing device or / and the control device
The control gas can be introduced into the exhaust gas recirculation device.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall configuration diagram showing an embodiment of an intake negative pressure control device for an internal combustion engine according to the present invention. In FIG. 1, a throttle valve 2 is disposed in a collecting portion 1a of an intake pipe 1, and an actuator 3 formed of, for example, a stepping motor is connected to the throttle valve 2. The actuator 3 is an electronic control unit (hereinafter referred to as “EC
U ”), and drives the throttle valve 2 according to a control signal from the ECU 4. A throttle valve opening (θTH) sensor 5 is mechanically connected to the throttle valve 2, and a detection signal thereof is supplied to the ECU 4.

An air cleaner 6 is provided at an upstream end of the collecting portion 1a of the intake pipe 1. A bypass pipe 7 for bypassing the throttle valve 2 is connected between the collecting section 1a of the intake pipe 1 and the branch pipe 1b on the downstream side thereof, and a bypass valve 8 made of a linear solenoid or the like is provided in the middle of the bypass pipe 7. Are arranged. The opening and closing of the bypass valve 8 is controlled by a signal from the ECU 4.

The branch pipe 1b of the intake pipe 1 has an intake air temperature (T
A) A sensor 9 and an intake pipe absolute pressure (PBA) sensor 10 are mounted, and these detection signals are supplied to the ECU 4.

The fuel injection valve 11 is provided for each cylinder in a branch pipe 1b of the intake pipe 1 slightly upstream of the engine 12. Further, each fuel injection valve 11 is connected to a fuel pump 14 via a fuel supply pipe 13 and is also electrically connected to the ECU 4, and a signal from the ECU 4 controls a valve opening time of the fuel injection.

An intake valve 16 is mounted on an intake port 15 of the engine 12, and valve timing (valve opening timing and valve lift) is controlled by a control signal from the ECU 4 via a hydraulically driven valve unit to be described later. Meanwhile, engine 1
An exhaust valve 18 is mounted on the second exhaust port 17, and the valve timing is similarly controlled via a hydraulically driven valve unit by a control signal from the ECU 4.

An engine cooling water temperature (TW) sensor 19 is mounted on the cylinder peripheral wall of the engine 12 and its detection signal is E.
It is supplied to CU4. An engine speed (NE) sensor 20 is arranged opposite to the crankshaft of the engine, generates a pulse signal (TDC signal) at each predetermined crank angle of each cylinder, and supplies the pulse signal to the ECU 4.

The cylinder head 12a of the engine 12 is provided with a hydraulic pressure (TOIL) sensor 21.
The IL sensor 21 detects the temperature of hydraulic oil of a hydraulic drive unit described later and supplies a detection signal to the ECU 4.

The cylinder head 12 of the engine 12
a of the intake pipe assembly 1a on the upper side of the
Are communicated via a fresh air introduction pipe 22 and the upper part of the cylinder head 12a and the branch pipe 1b are communicated via a blow-by gas reduction pipe 23. Thus, by slightly closing the throttle valve 2 and setting the branch pipe 1b to a weak negative pressure, fresh air is introduced into the engine 12 and blow-by gas leaking from the combustion chamber to the crankcase through the cylinder peripheral wall is blow-by gas. Reduction tube 23
Then, the blow-by gas can be returned to the combustion chamber again via the branch pipe 1b, so that the blow-by gas can be re-burned.

A pipe 24 branches off from the branch pipe 1b, and a vacuum tank 26 is provided at the end of the pipe 24 via a check valve 25. The vacuum tank 26 is provided with a tank internal pressure (VP) sensor 27. The pressure in the vacuum tank 26 detected by the VP sensor 27 is converted into an electric signal,
It is supplied to CU4.

An exhaust gas recirculation passage 28 is provided between the branch pipe 1b and the exhaust pipe 101 in a bypass shape.

Further, an exhaust gas recirculation amount control valve (hereinafter, referred to as an EGR valve) 29 is interposed in the exhaust gas recirculation passage 28. The EGR valve 29 includes a valve chamber 30 and a diaphragm chamber 3.
1, a wedge-shaped valve body 33 which is disposed in the valve chamber 30 and is vertically movable so that the exhaust gas recirculation passage 28 can be opened and closed; Axis 3
Diaphragm 35 connected to the valve body 33 via
And a spring 36 for urging the diaphragm 35 in the valve closing direction.
It is composed of Also, the diaphragm chamber 31
Atmospheric pressure chamber 3 defined on the lower side via diaphragm 35
7 and a negative pressure chamber 38 defined on the upper side.

The atmospheric pressure chamber 37 is communicated with the atmosphere through a vent hole 37a, while the negative pressure chamber 38 is connected to a negative pressure communication passage 39.
It is connected to the. That is, the distal end of the negative pressure communication passage 39 is connected to the vacuum tank 26, and the negative pressure in the vacuum tank 26 is introduced into the negative pressure chamber 38 through the negative pressure communication passage 39. A pressure regulating valve 40 is provided in the middle of the negative pressure communication passage 39. The pressure regulating valve 40 is a normally closed solenoid valve, and the atmospheric pressure or the negative pressure is selectively supplied to the negative pressure chamber 38 of the diaphragm chamber 31 through the pressure regulating valve 40, and the negative pressure chamber 38 Generates a predetermined control pressure. That is, when the pressure regulating valve 40 operates, the solenoid valve opens and a negative pressure is introduced into the negative pressure chamber 38. When the pressure regulating valve is in the non-operating state, the solenoid valve closes,
Atmospheric pressure is introduced into the negative pressure chamber 38 through an air inlet 41.

Further, the EGR valve 29 is provided with a valve opening (lift) sensor (hereinafter referred to as "L sensor") 42. The L sensor 42 is an operating position of the valve body 33 of the EGR valve 29. (A valve lift amount), and a detection signal is supplied to the ECU 4.

Further, a purge pipe 43 is provided branching from the branch pipe 1b.
4 is connected.

Thus, the fuel vapor treatment device 44 is provided with a fuel tank 46 having a filler cap 45 which is opened when fuel is supplied, and an activated carbon 47 as an adsorbent. A canister 48 for adsorbing and storing; an evaporative fuel flow passage 49 connecting the canister 48 and the fuel tank 46;
9 includes a two-way valve 50 including a positive pressure valve and a negative pressure valve.

Further, in the evaporative fuel processing apparatus 44, a hot-wire type flow meter (hereinafter simply referred to as "flow meter") 51 is interposed in the purge pipe 43 near the canister 48, and further downstream of the flow meter 51. In the middle of the purge pipe 43, a purge control valve 52 and an electromagnetic on-off valve 53 are interposed respectively.

The flow meter 51 utilizes the fact that when a platinum wire heated through an electric current is exposed to an air current, the temperature of the platinum wire decreases and its electric resistance decreases. It changes in accordance with the concentration, flow rate, and the like, and supplies an output signal corresponding to these changes to the ECU 4.

The purge control valve 52 is defined by a diaphragm 54 into a first chamber 55 and a second chamber 56, and a spring 57 for pressing the diaphragm 54 is contracted in the first chamber 55. I have. And the purge control valve 5
2, when the electromagnetic on-off valve 53 is opened, the diaphragm 54 moves upward in the drawing against the elastic urging force of the spring 57, and the fuel vapor stored in the canister 48 is branched through the purge pipe 43. It is purged to 1b.

A vacuum booster 58 having a master bag is connected to the vacuum tank 26. The brake booster 58 is configured to be supplied with a negative pressure in the vacuum tank 26 and to obtain a strong braking force with a small depression force of a brake pedal.

The ECU 4 has an accelerator opening (θACC) sensor 59 for detecting the amount of depression of the accelerator pedal as a parameter indicating the driver's request for the engine.
And an atmospheric pressure (PA) sensor 100 for detecting the atmospheric pressure are electrically connected.
A detection signal of the A sensor 100 is supplied to the ECU 4.

Thus, the ECU 4 has an input circuit having a function of shaping the input signal waveforms from the above-described various sensors to correct the voltage level to a predetermined level, converting an analog signal value to a digital signal value, and the like. A central processing unit (hereinafter referred to as a “CPU”); storage means including a ROM and a RAM for storing various operation programs executed by the CPU, various maps described later, operation results, and the like; An output circuit for supplying a drive signal to the pump 14, the pressure regulating valve 40, the electromagnetic on-off valve 53, a hydraulic drive unit described later, and the like is provided.

FIG. 2 is a cross-sectional view showing details of the intake-side valve operating mechanism. An intake valve 16 is provided at an intake port 15 of the engine 12. The intake valve 16 is arranged so as to be movable in the vertical direction in the drawing in the cylinder head 12a to open and close the intake valve port 61. Flange 6 of intake valve 16
A valve spring 63 is contracted between the cylinder head 12 and the cylinder head 12a, and the intake valve 16 is elastically urged upward (in the valve closing direction) in the figure by the valve spring 63.

On the other hand, on the left side of the intake valve 16 in FIG.
A camshaft 65 having a rotary shaft 4 is rotatably provided. The cam shaft 65 is connected to a crank shaft (not shown) via a timing belt (not shown). And
A hydraulic drive valve unit 60 is interposed between the cam 64 formed integrally with the cam shaft 65 and the intake valve 16.

The hydraulic drive valve unit 60 presses the intake valve 16 downward against the resilient urging force of the valve spring 63 in accordance with the profile of the cam 64 to drive the hydraulic drive mechanism 60A to open and close.
And a hydraulic pressure release mechanism 60B that nullifies the pressing force of the hydraulic drive mechanism 60A during the valve opening operation and closes the intake valve 16 regardless of the cam profile.

The hydraulic drive mechanism 60A includes a cylinder head 1
1a fixed to a block 66 integrally formed with the
And a valve-side piston (valve driving piston) which is slidably fitted into a cylinder hole 67a of the first cylinder body 67 with its lower end (front end) abutting on the upper end (rear end) of the intake valve 16. ) 68, an operating hydraulic chamber 69 defined by the first cylinder body 67 and the valve-side piston 68, and the block 6
6, a lifter 71 slidably contacting the cam 64, and a lower end contacting the lifter 71 slidably fitted to a lower portion of the second cylinder body 70. The main constituent elements are a cam-side piston 72, a hydraulic pressure generating chamber 73 defined by the second cylinder body 70 and the cam-side piston 72, and an oil passage 74 that connects the hydraulic pressure generating chamber 73 and the working hydraulic chamber 69. When the hydraulic pressure in the working hydraulic chamber 69 is equal to or higher than a predetermined value, the intake valve 1
6 is opened and closed.

The block 66 includes a flange 62 of the intake valve 16.
A valve lift sensor 75 is disposed at a position facing the valve lift sensor 75. The valve lift sensor 75 is electrically connected to the ECU 4, detects a valve lift of the intake valve 16, and supplies a detection signal to the ECU 4.

On the other hand, the hydraulic release mechanism 60B is
An oil passage 77 connecting the oil supply gallery 4 to the oil supply gallery 76; a spill valve 78 interposed in the oil passage 77; a feed valve 79 and a check valve 80 arranged in the oil passage 77; The accumulator 82 for maintaining the release hydraulic pressure in the accumulator circuit 81a defined by the valves 79, 80 and the spill valve 78 is a main component. The solenoid 78a of the spill valve 78 is connected to the ECU 4 and is excited or demagnetized by a control signal thereof. The refueling gallery 76 is provided for supplying hydraulic pressure to a hydraulic drive valve unit provided for each cylinder, and is connected to the oil pump 83. The oil pump 83 supplies hydraulic oil in an auxiliary oil pan 84 provided in the cylinder head 12a to the oil supply gallery 76 as oil pressure within a predetermined range. The hydraulic oil supplied to the oil supply gallery 76 may be supplied by an oil pump from an oil pan provided below a crankcase (not shown).

The accumulator 82 includes a hydraulic release mechanism 60
A cap 87 having a cylinder hole 85, an air hole 86, and a cylinder hole 85 provided in the accumulator circuit 81 for accumulating the hydraulic pressure and the drain oil released by the spill valve 78 of B. A piston 88 slidably fitted to the cap, a cap 87 and the piston 88
And a spring 89 contracted between them.

The hydraulic drive mechanism 60 constructed as described above
The operation of A and the hydraulic release mechanism 60B will be described below.

When the solenoid 78a of the spill valve 78 is excited by a control signal from the ECU 4, the spill valve 78 is closed, and the hydraulic pressure generating chamber 73, the oil passage 74, and the working hydraulic chamber 69 of the hydraulic drive mechanism 60A are closed. Is maintained at a high pressure equal to or higher than a predetermined value, and the opening and closing of the intake valve 16 is performed according to the profile of the cam 64. Therefore, the valve operating characteristics in this case (the relationship between the crank angle and the valve lift)
Is as shown by the solid line in FIG.

On the other hand, when the solenoid 78a of the spill valve 78 is demagnetized by a control signal from the ECU 4 when the intake valve 16 is opened, the spill valve 78 is opened, and the hydraulic pressure generating chamber 73 of the hydraulic drive mechanism 60A and the oil The hydraulic pressure in the passage 74 and the hydraulic pressure chamber 69 decreases, and the intake valve 16 starts the valve closing operation regardless of the profile of the cam 64. At this time, the closing speed of the intake valve 16 is relaxed during the closing operation by the hydraulic oil return amount limiting mechanism provided on the valve-side piston 68, and the intake valve 16 is gently seated on the valve seat 90. The valve operating characteristic in this case is as shown by the broken line in FIG. That is,
In the figure, when the solenoid 78a is demagnetized at the crank angle θOFF, the intake valve 16 starts the valve closing operation slightly after θOFF (θ = θST), and the valve closing is completed at θ = θIC.

As described above, the spill valve 78 is opened / closed by the control signal from the ECU 4 and the operation of the hydraulic drive mechanism 60A is invalidated at the time of opening the spill valve 78.
The valve closing start timing (valve closing timing) of the intake valve 16 and, accordingly, the valve opening period can be arbitrarily set. As a result, the intake air amount of each cylinder can be controlled by the control signal of the ECU 4.

In this embodiment, the same hydraulic drive valve unit (not shown) is provided on the exhaust valve side as on the intake valve side, but the exhaust valve side normally closes at a constant timing according to the cam profile. Or a variable valve timing mechanism capable of setting a plurality of opening / closing timings.

Next, a control procedure of the intake negative pressure control executed in this embodiment will be described.

FIG. 4 is a flowchart of an intake negative pressure control routine. This program is executed, for example, in synchronization with generation of a TDC signal pulse.

First, at step S1, the flag FNON
It is determined whether or not H is “1”, and it is determined whether or not the engine is in the non-throttling operation region. Here, whether or not the vehicle is in the non-throttling operation region is determined by a non-throttling operation region determination routine (not shown). Specifically, when the engine is in a start mode (for example, during cranking), and when the oil temperature TOIL detected by the TOIL sensor 21 is lower than a predetermined temperature (for example, 20 ° C.),
Alternatively, when the accelerator opening θACC detected by the θACC sensor 59 is in a high-load operation region equal to or larger than a predetermined angle (for example, 50 °), it is determined that the engine is in the throttling operation region.

When the flag FNONTH is "0", that is, when the engine is in the throttling operation region, the routine proceeds to step S10, in which a predetermined throttling operation is performed to control the intake air amount by the valve opening θTH of the throttle valve 2. I do.

On the other hand, at step S1, the flag FNONTH is set.
Is “1”, that is, when it is determined that the vehicle is in the non-throttling operation region, the process proceeds to step S2, and the flag FE
It is determined whether the GR or the flag FPUG is “1”. That is, in step S1, whether the engine 12 is in the operation region (EGR region) of the EGR valve 29 or the region (purge region) in which the electromagnetic on-off valve 53 is opened to purge the intake pipe 1 with the fuel vapor is opened. It is determined whether or not there is.

Whether or not the engine is in the EGR range is specifically determined as shown in FIGS. 5 (a) and 5 (b).
pm), the accelerator opening θACC (°), and the engine cooling water temperature TW. Specifically, the engine speed is within a predetermined speed (for example, 900 rpm <NE <380).
0 rpm), the accelerator opening is within a predetermined angle (for example, 10 ° <θACC <50 °), and the engine cooling water temperature TW is equal to or higher than a predetermined temperature (for example, 60 ° C.), it is determined that the engine is in the EGR region. You. That is, when the engine is in the idling region, the high load operation region, the high rotation speed region, and the deceleration region, and when the engine cooling water temperature is low and the warming-up has not yet been completed, the EGR valve 29 is closed and the exhaust gas recirculation is performed. Not performed. Further, whether or not the fuel is in the purge area is determined, for example, by estimating the fuel vapor stored in the canister 48 based on the purge flow rate detected by the flow meter 51. It is determined that it is in the area.

Then, the flag FEGR or the flag FPU
When G is determined to be “1”, the process proceeds to step S3, where θ
The basic opening value θTHTRGM of the throttle valve 2 is calculated by searching the THTRGM map.

The θTHTRGM map is specifically shown in FIG.
, The accelerator opening degrees θACC00 to θACC1
5 and the engine speeds NE00 to NE15 in a matrix form in the form of map values θTHTRGM (00, 00) to
θTHTRGM (15, 15) is given. In the θTHTRGM map, map values are given according to the accelerator opening θACC and the engine speed NE so that the intake negative pressure in the branch pipe 1b becomes a predetermined negative pressure that is slightly negative, for example, about −60 mmHg. The basic opening value θTHTRGM of the throttle valve 2 is read out by searching the θTHTRGM map, or is calculated by an interpolation method. The predetermined negative pressure may be set according to the exhaust gas recirculation amount or the purge supply amount.

Next, at step S4, the valve opening correction coefficient K
TH and a feedback correction coefficient KFBTH are calculated. The valve opening correction coefficient KTH is calculated based on the atmospheric pressure PA and the intake air temperature TA.
The feedback correction coefficient KFBTH is set to a predetermined value according to the intake pipe absolute pressure PBA.

Next, at step S5, the opening degree θTH of the throttle valve 2 to be kept at a constant negative pressure based on the equation (1).
Calculate TRG.

ΘTHTRG = θTHTRGM × KTH × KFBTH (1) Next, in step S6, the valve opening degree θTH of the throttle valve 2 is set.
Is set to the valve opening θTHTRG obtained by Expression (1), and the control of the intake air amount based on the valve timing of the intake valve 16 is executed.

As a result, the exhaust gas can be recirculated to the intake pipe 1 and the fuel vapor can be purged to the intake pipe 1 without any trouble, and these negative pressure devices can be utilized.

On the other hand, when the flag FEGR and the flag FPUG are both "0" in step S2, that is, when it is determined that the engine is not in the EGR region or the purge region, the process proceeds to step S7, and a predetermined non-throttling operation is performed. .

At this time, non-throttling operation may be performed by closing the throttle valve by a predetermined angle and setting the inside of the branch pipe to a weak negative pressure (for example, about -40 mmHg).
When the intake valve 16 is closed, the pulsation of the air flow in the branch pipe 1b when the intake valve 16 is almost fully closed can be prevented to avoid the generation of intake noise, and the inside of the branch pipe 1b is set to the above-mentioned weak negative pressure. This is also advantageous for the reduction of blow-by gas.

Next, the routine proceeds to step S8, where the tank internal pressure PC in the vacuum tank 26 becomes equal to the predetermined tank internal pressure PCLL.
It is determined whether it is smaller than. And PC <PCLL
Is established, it is determined that the pressure in the vacuum tank 26 is low, and a throttling operation of controlling the intake air amount by controlling the opening degree of the throttle valve 2 to supply a negative pressure into the vacuum tank 26 is performed. Exit this program.

As a result, a negative pressure is always accumulated in the vacuum tank 26, and the brake booster 58 can be always driven by the negative pressure.

FIG. 7 is a diagram showing a fuel efficiency improvement ratio with respect to the intake negative pressure of the present embodiment together with a comparative example. A point a indicates the present embodiment, that is, the negative pressure in the intake pipe 1 is controlled to a constant value. When the intake air amount is controlled by the valve timing, the point b
Indicates a normal non-throttling operation, point c indicates a throttling operation, and point d indicates a case where a negative pressure is forcibly supplied to a negative pressure device using an air pump.

As is apparent from FIG. 7, the pumping loss occurs during the throttling operation, so that the fuel efficiency is poor. Further, when the air pump is used, the fuel efficiency is considerably reduced as compared with the non-throttling operation due to the driving loss of the air pump. On the other hand, in the present embodiment, the negative pressure in the intake pipe 1 makes it possible to prevent fuel consumption from deteriorating not only during the throttling operation but also when the air pump is used, although the fuel efficiency is somewhat reduced. That is, it is possible to use the negative pressure device while ensuring low fuel consumption.

FIG. 8 shows the fuel efficiency improvement ratio with respect to the intake negative pressure depending on whether EGR is introduced or not. The solid line shows the case where EGR is introduced, and the broken line shows the case where EGR is not introduced.
The point a is in the present embodiment, that is, when the EGR is introduced at a constant negative pressure, the point b is the EGR during the non-throttling operation.
Is not introduced.

As is apparent from FIG. 8, it is understood that fuel efficiency can be improved by introducing EGR even in non-throttling operation.

[0069]

As described above, the intake negative pressure control device for an internal combustion engine according to the present invention has a pressure accumulating means for accumulating a negative pressure in an intake pipe, a pressure detecting means for detecting a pressure of the pressure accumulating means, and an engine. Operating state detecting means for detecting an operating state of the operating area, and operating area determining means for determining whether or not the operating area is in an operating area in which the intake air amount is controlled only by the intake valve based on the detection result of the operating state detecting means. When the pressure detected by the pressure detecting means is equal to or less than a predetermined value even when it is determined that the operating area determining means is in an operating area in which the intake air amount is controlled only by the intake valve. Since it has intake negative pressure generating means for generating negative pressure in the intake pipe by the intake valve and the throttle valve,
It is possible to generate the necessary minimum intake negative pressure in the operation region of the negative pressure device that uses the negative pressure in the intake pipe as a driving force source, and it is possible to use the negative pressure device while ensuring low fuel consumption.

Also, when a vehicle brake booster is used as a negative pressure device, a negative pressure is generated in the intake pipe when the pressure of the pressure accumulating means is equal to or lower than a predetermined value, and this negative pressure is transmitted through the pressure accumulating means. Since the vehicle is supplied to the vehicle brake booster, a desired braking operation can always be performed.

Further, even when the operating area determining means determines that the operating area is in the operating area in which the intake air amount is controlled only by the intake valve, at least the specific operating state in which the control gas should be introduced into the control device. In this case, since the intake valve and the throttle valve have intake negative pressure setting means for setting the inside of the intake pipe to a predetermined negative pressure, the intake air amount can be easily controlled, and the throttle valve Since the pressure difference before and after is constant, the accuracy of the flow rate control of the negative pressure device is also improved.

Further, even when the evaporative fuel treatment device is used as the negative pressure device, the inside of the intake pipe is maintained at a predetermined negative pressure, so that the purge flow rate can be accurately controlled.

Further, even when an exhaust gas recirculation device is used as a negative pressure device, it is possible to operate the device with a minimum negative pressure, thereby ensuring low fuel consumption.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of an intake negative pressure control device for an internal combustion engine according to the present invention.

FIG. 2 is a sectional view showing details of an intake-side valve operating mechanism.

FIG. 3 is an operation characteristic diagram of an intake valve.

FIG. 4 is a flowchart of an intake negative pressure control routine.

FIG. 5 is a diagram showing an EGR region.

FIG. 6 is a θTHTRGM map.

FIG. 7 is a characteristic diagram showing a fuel efficiency improvement ratio with respect to an intake negative pressure according to the present embodiment together with a comparative example.

FIG. 8 is a characteristic diagram showing a fuel efficiency improvement ratio with respect to intake negative pressure depending on whether EGR is introduced or not.

[Explanation of symbols]

 2 Throttle valve 12 Internal combustion engine 16 Intake valve 19 TW sensor (Operating state detecting means) 20 NE sensor (Operating state detecting means) 21 TOIL sensor (Operating state detecting means) 26 Vacuum tank (Pressure accumulating means) 27 VP sensor (Pressure detecting means) ) 28 Exhaust gas recirculation path 29 EGR valve 58 Vehicle brake booster 59 θACC sensor (operating state detecting means)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-301452 (JP, A) JP-A-2-283384 (JP, A) JP-A 2-144637 (JP, U) JP-A 49- 16607 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02D 9/02 F02D 13/02 F02D 21/08 301 F02M 25/07 540 F02M 25/08 301 B60T 17/00

Claims (5)

(57) [Claims] 1. An intake valve whose opening period can be arbitrarily changed;
An intake negative pressure control device for an internal combustion engine having an electrically operated throttle valve and a control device that uses a negative pressure in an intake pipe as a driving force source, comprising: a pressure accumulator for accumulating a negative pressure in the intake pipe; Pressure detecting means for detecting the pressure of the engine, operating state detecting means for detecting the operating state of the engine, and detecting the operating state detecting means for determining whether or not the engine is in an operating area in which the intake air amount is controlled only by the intake valve. Operating region discriminating means for discriminating based on a result, even when it is determined that the operating region discriminating device is in an operating region in which the intake air amount is controlled only by the intake valve, the pressure detecting device An internal combustion engine having intake negative pressure generating means for generating a negative pressure in an intake pipe by the intake valve and the throttle valve when the detected pressure is equal to or lower than a predetermined value. Intake negative pressure control apparatus. 2. The intake negative pressure control device for an internal combustion engine according to claim 1, wherein the control device is a vehicle brake booster. 3. An intake valve whose opening period can be arbitrarily changed;
Operating state detecting means for detecting an operating state of the engine in an intake negative pressure control apparatus for an internal combustion engine having an electrically operated throttle valve and a control apparatus for controlling a control gas introduced by a negative pressure in the intake pipe; Operating region discriminating means for discriminating whether or not the engine is in an operating region in which the intake air amount is controlled only by the intake valve based on the detection result of the operating state detecting device. Even when it is determined that it is in the operating range in which the intake air amount is controlled only by the valve, when at least in the specific operating state in which the control gas is to be introduced into the control device, the intake valve and the throttle valve are used. An intake negative pressure control device for an internal combustion engine, comprising intake negative pressure setting means for setting a predetermined negative pressure in an intake pipe. 4. The control device includes: a fuel tank; a canister for adsorbing and storing evaporative fuel generated from the fuel tank; a purge passage connecting the canister to an intake system of an internal combustion engine; 4. The negative pressure control apparatus for an internal combustion engine according to claim 3, wherein the apparatus is a fuel vapor processing apparatus having a purge control valve mounted thereon. 5. The intake negative pressure control device for an internal combustion engine according to claim 3, wherein the control device is an exhaust gas recirculation device that recirculates a part of exhaust gas to an intake pipe.