JPS62101825A - Intake device for engine - Google Patents

Abstract

PURPOSE:To relieve a torque shock by correcting a charging quantity by means of a timing valve when air-fuel ratio has changed under a low load, in a device having an intake passage for high load in which a shutter valve is provided and an intake passage for low load in which said timing valve is provided. CONSTITUTION:An intake passage 10 is branched off, on the lower course side of a surge tank 13, to an intake passage 10a for high load and an intake passage 10b for low load which is formed for producing a swirl, and a shutter valve 17 is provided in the passage 10a while a timing valve 18 is provided in the passage 10b. When air-fuel ratio varies suddenly, e.g., from a rich zone to a lean zone under a low load, the opening/closing timing of the timing valve 18 is delayed in the direction of increasing a charging quantity by a controller 21, to increase an overlapping quantity. On the contrary, when shifting to the rich zone, the timing of the timing valve 18 is controlled to be advanced. Thereby, variation in torque can be reduced.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention comprises an intake passage consisting of a high-load intake passage and a low-load intake passage, and a shutter that closes when the load is low. Provided with a valve - On the other hand, this invention relates to an improvement in an engine intake system that controls the filling amount by providing a timing valve in the low-load intake passage and making the timing valve close earlier than the intake port close timing in the low-load range. It is something.

(Prior art) Conventionally, in the case of an engine in which intake air charging IWLi is controlled by adjusting the opening of the throttle valve, there is a pumping loss due to throttling resistance, especially in the low load range, which makes it difficult to improve the fuel efficiency of the engine. It has become an obstacle.

As an engine that reduces this pumping loss, a timing valve is provided in the intake passage near the intake port that is opened and closed at a predetermined timing, and the opening and closing timing of the timing valve is adjusted according to the operating condition of the engine. In addition, an engine has been proposed in which the intake air filling is controlled by the length of the opening period of the timing valve, eliminating intake throttling resistance, reducing pumping loss, and improving fuel efficiency (for example, JP-A No. (See No. 58-23245).

In addition, in the above-mentioned prior example, the intake passage is configured into a high-load passage and a low-load passage, and the timing valve is interposed in the low-load passage, while the high-load passage has a shutter valve that closes at low load. In addition to reducing the pumping loss in the low load range, the timing valve was also made smaller to improve its reliability, and the intake passage for low loads was designed to be suitable for generating swirl. The passage structure can improve combustibility.

Therefore, in an engine equipped with a timing valve and a shutter valve as described above, when the air-fuel ratio is shifted to lean in a specific operating range where the required output is low in order to improve fuel efficiency, the operating state changes. For example, when the air-fuel ratio changes from a cold state to a warm state and the air-fuel ratio shifts to a lean state, or when the air-fuel ratio shifts to a rich state due to other conditions, a sudden change in output may occur if the charging amount is constant. Torque shock occurs when the torque decreases or increases.

Therefore, for example, when the air-fuel ratio shifts to lean, control has been carried out to increase the filling amount.
If this increase in the filling port is achieved by opening the shutter valve, the pumping loss reduction effect achieved by providing the timing valve will be impaired.

In other words, the pumping loss reduction effect of the above engine is
This is achieved by closing the timing valve and stopping the intake air supply in the latter half of the period when the intake port is open during low load conditions, and opening the shutter valve at this time will impair this pumping loss reduction effect. Undesirable.

(Object of the Invention) In view of the above-mentioned circumstances, the present invention provides a method for pumping loss when controlling the operation of a timing valve provided in a low-load intake passage and a shutter valve provided in a high-load intake passage according to the operating state. It is an object of the present invention to provide an intake system for an engine that reduces torque shock when changing the air-fuel ratio at low load while maintaining a reduction effect.

(Structure of the Invention) In the intake device of the present invention, the intake passage is composed of a high-load intake passage and a low-load intake passage, and the high-load intake passage is provided with a shutter valve that closes at low load. In an engine in which a timing valve is provided in the load intake passage and the closing timing of the timing valve is made earlier than the closing timing of the intake port under low load, when the air-fuel ratio is changed under low load, the timing control of the timing valve closes the air. The present invention is characterized in that it includes a controller that corrects the filling amount in a direction that reduces torque fluctuations caused by changes in fuel ratio.

(Effects of the Invention) According to the present invention, when the air-fuel ratio is changed to leaner or richer due to changes in the operating state of the engine during low load, the timing valve timing is adjusted at the same time as the air-fuel ratio is changed. By controlling and correcting the filling amount, it is possible to suppress the increase or decrease in output due to a change in the air-fuel ratio by increasing or decreasing the filling port, reduce the occurrence of torque shock, and obtain a good operating condition. In addition, by correcting the 114M by timing control of the timing valve, the above-mentioned torque shock can be improved without impairing the pumping loss reduction effect due to the installation of the timing valve.

(Example) Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is an overall configuration diagram of an engine equipped with an intake system of the present invention.

An intake port 7 that is opened and closed by an intake valve 6 for a combustion chamber 5 formed above the piston 4 between the cylinder head 2 and cylinder block 3 of each cylinder of the engine body 1;
and an exhaust port 9 which is opened and closed by an exhaust valve 8.

Intake passage 1 that communicates with the intake port 7 and supplies intake air
0 is equipped with an air cleaner 11, an intake air amount sensor 12 that detects the intake air amount, and a surge tank 13 from the upstream side, and branches from downstream of the surge tank 13 to each cylinder to form a high-load intake passage with a large passage area. 10a, and a low-load intake passage 10b which has a narrow passage area and is formed for swirl generation. Furthermore, a fuel injection nozzle 16 for injecting fuel is arranged in the high-load intake passage 10a of each cylinder.

A shutter valve 17 is interposed in the middle of the high-load intake passage 10a, while a timing valve 18 is interposed in the middle of the low-load intake passage 10k).

The timing valve 18 is formed into a cylindrical shape that is driven to rotate in synchronization with the engine rotation, and the timing valve 18 has an opening 18 that opens and closes the low-load intake passage 10b.
a is formed. The internal space of this timing valve 18 is an opening 18a for other cylinders of the multi-cylinder engine.
When the opening 18a of one cylinder is in an open state communicating with the downstream low-load intake passage 10b, the internal space is connected to the upstream low-load intake passage through the opening 18a of the other cylinder. It is connected to the intake passage 10b for supplying intake air.

On the other hand, the phase of the timing valve 18 with respect to the crank angle, that is, the opening/closing timing with respect to the intake port 7 is as follows.
It is configured to be variable by timing control means 19. Further, the opening degree of the shutter valve 17 is adjusted by an opening degree control means 20.

A control signal from the controller 21 is outputted to the timing control means 19 and the opening control means 20, which control the operation of the timing valve 18 and the shutter valve 17 according to the operating state. Also,
The controller 21 outputs a fuel injection signal to the fuel injection nozzle 16 to control the fuel injection amount and injection timing, and also outputs a control signal to the on-off valve 23 of the bleed air passage 22 to correspond to the fuel injection timing. This control is used to control the supply of bleed air.

The controller 21 receives, as signals for detecting the operating state of the engine, an intake air amount signal from the intake air amount sensor 12, a crank angle signal (engine rotation speed signal) from the crank angle sensor 24, and an accelerator signal from the accelerator sensor 25. , an intake pressure signal from the boost sensor 26, a cooling water temperature signal from the water temperature sensor 27, and the like are input.

The basic control of the opening/closing timing of the timing valve 18 and the opening degree of the shutter valve 17 is performed according to the load condition corresponding to the amount of accelerator operation, etc. When the load is low, the shutter valve 17 is closed, and when the load is above a predetermined load, the shutter valve 17 is closed.
7 is opened to an opening degree according to the load. on the other hand,
The intake port 7 is opened and closed at certain times relative to the crank angle, and the timing valve 18 closes the intake port 7 at low load.
It opens faster and closes faster. As a result, when the load is low, intake air is supplied to the combustion chamber 5 during the overlap period when both the timing valve 18 and the intake port 7 are open. And the timing valve 18
The opening/closing timing of both pulps 6.1 and 6.1 is controlled to be delayed as the load increases, depending on the operating state of the engine.
8 increases the filling period by lengthening the open overlap period, that is, the intake period.

In addition, the fuel injection control by the controller 21 leans the air-fuel ratio in a medium-load, medium-speed range, etc. where the required output is low and stability is ensured, and makes the air-fuel ratio rich in a high-load, high-speed range, etc. The fuel injection amount is controlled so that the Further, even in the lean region □, lean operation is not performed when the engine temperature is low, but transitions to lean operation when the engine temperature rises to a predetermined value or higher.

In the air-fuel ratio control as described above, when the air-fuel ratio suddenly changes from a rich region to a lean region at low load, for example, the opening/closing timing of the timing valve 18 is delayed so that the filling mass increases in order to compensate for the decrease in output. This increases overlap suspension. Conversely, when shifting to rich, the timing of the timing valve 18 is advanced. Timing valve 1 due to this air-fuel ratio fluctuation
The change in step 8 is performed only when the air-fuel ratio fluctuates, and once the transition has occurred, the timing is returned to the original timing.

The control of the timing valve 18 and shutter valve 17 by the controller 21 will be explained with reference to the flowchart of FIG. 2 (only main parts are shown). After the start,
The controller 21 controls the boost sensor 2 in step S1.
The boost P (intake pressure) based on the signal of No. 6, the engine rotation speed N based on the signal of the crank angle sensor 24, and the intake air mQa from the intake air amount sensor 12 are read. In step S2, a target overlap fmAt between the open period of the intake port 7 and the open period of the timing valve 18, that is, the intake period (filling amount) is calculated based on the detection signal.

Then, in step S3, it is determined whether the current state is in a lean region,
If YES in the lean region, it is determined in step S4 whether or not it was in the rich region last time.

When the determination in step S4 is YES and the transition is made from the rich region to the lean region, the air-fuel ratio change ΔA is determined in step S6.
The torque change 96 (decrease) during lean transition corresponding to /F is calculated, and in step S7, the overlap correction amount ΔA (increase) of the timing valve 18 is calculated from this torque change ΔK.

Step S9 corrects the target overlap mAt obtained in step S2 by the correction amount ΔΔ,
Based on this corrected target overlap it A1, the timing of the timing valve 18 is corrected in the direction of delay in step S10.

On the other hand, if the determination in step S3 is NO and the vehicle is currently in the rich region, it is determined in step $5 whether or not the vehicle is in the one-run region. When the determination in step S5 is YES and the transition has occurred from the lean region to the rich region, the process proceeds to step S6, where the torque change (96 teeth) corresponding to the air-fuel ratio change ΔA/F during the rich transition (
increase), and in step S7 calculate this torque change ΔT.
The overlap correction amount ΔA of the timing valve 18
(decrease) is calculated, and the timing of the timing valve 18 is corrected in the advancing direction.

Further, if the determination in step S5 is N-0, or if the determination in step S4 is No and there is no change in the air-fuel ratio in the rich or lean region, the overlap correction amount ΔA is set to O in step S8. After setting, the process proceeds to step S9, and the timing correction of the timing valve 18 is not performed.

The setting of the air-fuel ratio control region in the determination of steps S3 to S5 above is such that, for example, in the relationship between the load based on boost P and the engine rotation speed N, the low load low rotation region and the high load high rotation region are rich regions. , the middle load/mid-rotation region is the one-in region, and the stoichiometric air-fuel ratio region is set between the rich region and the lean region. The above rich region ensures stability in the idle region side where the filling amount is small,
The purpose is to ensure output under high load and high rotation speeds, and the lean region is intended to improve fuel efficiency in a region where no output is required.

With the above configuration, when the output fluctuates due to a sudden change in the air-fuel ratio during low load, the timing of the timing valve 18 is changed in a direction to reduce this output fluctuation.
This is to correct the four amounts and reduce the occurrence of torque shock. At that time, the shutter valve 17 is in the closed state, and the pumping loss reducing effect by the timing valve 18 is maintained.

In the above embodiment, the intake air amount is adjusted by the shutter valve 17 provided for each cylinder during high load, but this intake air amount adjustment is performed by a throttle valve common to all cylinders further upstream. Alternatively, a shutter valve that closes under light loads may be simply interposed in the high-load intake passage.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an engine equipped with an intake system according to an embodiment of the present invention, and FIG. 2 is a flowchart for explaining the operation of a controller. 1... Engine body 4... Piston 6... Intake valve 7...
Intake port 10...Intake passage 10a...High load intake passage 10b...Low load intake passage 17...Shutter valve 18...・Timing valve 19... Timing control means 20... Opening degree control means 21... Controller Fig. 2

Claims (1)

[Claims] (1) The intake passage consists of a high-load intake passage and a low-load intake passage, and the high-load intake passage is equipped with a shutter valve that closes at low loads, while the low-load intake passage is equipped with a timing valve. In an engine in which the timing valve close timing is earlier than the intake port closing timing during low load, when the air-fuel ratio is changed during low load, torque fluctuations accompanying the air-fuel ratio change are reduced by timing control of the timing valve. An engine intake device characterized by comprising a controller that corrects a filling amount in a direction.