JPH04232326A - Intake device of engine - Google Patents

Abstract

PURPOSE:To secure accelerating performance while improving distributive property of EGR at the time of normal operation in an intake device which is provided with a communication passage which for providing communication between collected intake passages for respective two cylinder groups comprising the cylinders whose sequential number of intake are not continuous, and a control valve which opens and closes the communication passage, and in which an EGR passage is opened to a common intake passage positioned upstream from the collected intake passage. CONSTITUTION:There are provided a control means 31 which performs opening/ closing action of control valves 14, 15 of communication passages 12, 13 respectively according to an operation condition, and a control variation means 34 which stops control of opening/closing a control valve in EGR range so as to place the control valve in its closed state, but has opening/closing control of the control valve performed even in the EGR range in the case of acceleration.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake system for an engine having an intake system configured to provide a dynamic intake effect such as a resonance effect and an EGR passage.

0002

2. Description of the Related Art Conventionally, as shown in Japanese Utility Model Application Publication No. 1-162038, two cylinder groups are provided, each consisting of cylinders in which the intake order is not consecutive, and an independent intake passage communicating with each cylinder is provided in the cylinder group. In this engine, the collective intake passages for each cylinder group are assembled into an upstream common intake passage, the two collective intake passages are communicated by a communication passage, and a control valve is provided to open and close this communication passage. Inhalation devices are known. According to such an intake device, the pressure propagation path changes by opening and closing the communication passage by the control valve,
Since the intake inertia or resonance tuning speed changes, by switching and controlling the opening and closing of the above control valve according to the engine speed, dynamic effects of the intake air can be obtained in various speed ranges, increasing charging efficiency. It will be done.

0003

[Problems to be Solved by the Invention] Incidentally, engines equipped with an exhaust gas recirculation (EGR) device that recirculates part of exhaust gas to the intake system in order to reduce NOx, etc. have been generally known for a long time, and the above-mentioned Even in intake systems configured to obtain dynamic effects of intake air in various rotational speed ranges, there are some in which, for example, an EGR passage is opened in an upstream common intake passage and EGR gas is introduced into the intake passage. However, in engines equipped with such an intake device and an EGR device, the following problems remain.

[0004] That is, in general, the EGR device described above is provided with an EGR valve that operates in response to intake negative pressure, etc., in the EGR passage, so that the EGR passage is opened in a specific area (EGR area) excluding high load areas. It has become. When the EGR passage is open, EGR gas is distributed to each cylinder from the upstream common intake passage through each collective intake passage, but in this case, if the communication passage is opened, EGR moves between both intake passages, and EGR distribution tends to deteriorate. Therefore, as a countermeasure to this deterioration in EGR distribution, it is conceivable to stop the opening/closing control of the control valve in the EGR region and maintain the communication passage in a closed state. However, even in the EGR region up to a medium load level, engine output is required during acceleration, and stopping the opening/closing control of the opening/closing valve will result in a decrease in acceleration performance.

SUMMARY OF THE INVENTION In view of these circumstances, it is an object of the present invention to provide an engine intake system that can ensure acceleration performance while improving EGR distribution during steady operation.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention includes two cylinder groups each consisting of cylinders in which the intake order is not consecutive, and an independent intake passage communicating with each cylinder is provided in each cylinder. The collective intake passages for each cylinder group are assembled into an upstream common intake passage, and both the collective intake passages are communicated by a communication passage, and a control valve is provided to open and close this communication passage. In an intake system for an engine in which an EGR passage for guiding EGR gas opens into the common intake passage, the control means opens and closes the control valve according to the operating state, and the EGR region determining means determines an operating region in which EGR is performed. , acceleration determining means for determining the acceleration state of the engine; and based on the determinations of these determining means, in the operating region where EGR is performed, the control by the control means is stopped and the control valve is closed; The control change means causes the control valve to be opened and closed according to the operating state by the control means even in an operating region where EGR is performed.

[0007]

[Function] According to the above structure, when the EGR is performed in an operating range other than during acceleration, the control valve is closed, so that EGR does not flow unnecessarily through the communication path. When accelerating in an operating range where the engine is operated, control valve opening/closing control is performed preferentially to enhance the dynamic effect.

[0008]

[Embodiment] An embodiment of the present invention will be explained based on the drawings.

FIGS. 1 and 2 show an embodiment of the present invention. 1 is an engine, and the illustrated engine 1 is the first engine.
It is a V-type six-cylinder engine having six cylinders 2a to 2f. This engine 1 includes a pair of banks 1a and 1b arranged in a V shape, one bank 1a is provided with a first cylinder 2a, a third cylinder 2c and a fifth cylinder 2e, and the other bank 1b is provided with a second cylinder. 2b, a fourth cylinder 2d, and a sixth cylinder 2f. The order of the intake stroke of each cylinder is: 1st cylinder 2a → 6th cylinder 2f → 3rd cylinder 2c
→Second cylinder 2b→Fifth cylinder 2e→Fourth cylinder 2d.

These cylinders form a first cylinder group 3a consisting of cylinders 2a, 2c, and 2e belonging to one bank 1a.
and a second cylinder group 3b consisting of cylinders 2b, 2d, and 2f belonging to the other bank 1b.
The cylinders a and 3b are each composed of cylinders whose intake strokes are not consecutive.

The intake passage 5 that supplies intake air to each cylinder includes:
A first collective intake passage 7a that collects independent intake passages 6a, 6c, and 6e that communicate with the intake ports 4 of each cylinder 2a, 2c, and 2e of the first cylinder group 3a, and each cylinder 2 of the second cylinder group 3b.
A second collective intake passage 7b is formed by collecting independent intake passages 6b, 6d, and 6f that communicate with the intake ports 4b, 2d, and 2f. These first and second collective intake passages 7a
, 7b are gathered on the upstream side, and the common intake passage 8 on the upstream side
It is connected to An air cleaner 9, an air flow meter 10, and a throttle valve 11 are arranged in this common intake passage 8.

The above-mentioned collective intake passages 7a, 7b have an upstream side connected to the common intake passage 8, an end portion opposite to the common intake passage side, and an intermediate portion via communication passages 12, 13. are connected to each other. The communicating passages 12 and 13 are operated by actuators 16 and 17 to
Control valves 14 and 15 are provided to open and close valves 2 and 13. These control valves 14 and 15 are operated by, for example, negative pressure responsive actuators 16 and 17, and the negative pressure supply to these actuators 16 and 17 is controlled by three-way solenoid valves 18 and 19.
It is now controlled by.

Reference numeral 21 denotes an EGR passage for recirculating exhaust gas to the intake system, and the end of the EGR passage 21 on the intake passage side opens into the common intake passage 8,
GR gas flows from the common intake passage 8 to each collective intake passage 7a, 7.
b and is sent to each cylinder. This EGR passage 21 is provided with an EGR valve 22. The EGR valve 22 is operated by, for example, an actuator that responds to the pressure within the intake passage.

Reference numeral 30 denotes a control unit (ECU), which includes a throttle opening sensor 25 that detects the opening of the throttle valve 11 (throttle opening), a rotational speed sensor 26 that detects the engine rotational speed, and an intake negative pressure. The control valves 14 and 15 are controlled by receiving signals from the negative pressure sensor 27, the air flow meter 10, etc., and outputting control signals to the three-way solenoid valves 18 and 19.

The control unit 30 includes a control means 31 that opens and closes the control valves 14 and 15 according to the operating state, an EGR region determining means 32 that determines the operating region in which EGR is performed, and an acceleration state of the engine. It is configured to perform the functions of acceleration determining means 33 and control changing means 34.

The control by the control means 31 includes, for example, as shown in FIG. 3, the engine operating range is divided into a plurality of rotation speed ranges at the set rotation speeds N1, N2, N3, N4, and N5 for switching control valves. The open/close states of the control valves 14 and 15 are set for each rotation speed region so that the dynamic effect of intake can be obtained in each rotation speed region on the high load side (see Fig. 4). Control shall be carried out accordingly. Further, EGR is performed, for example, in low and medium load regions (the hatched region in FIG. 3), and is stopped on the high load side where the intake negative pressure becomes smaller than a predetermined value. Such a region where EGR is performed and a region where EGR is stopped are determined based on detection of intake negative pressure and the like. The acceleration state is determined, for example, by checking the rate of change in the throttle opening.

Furthermore, the processing by the control changing means 34 includes EGR region determination and acceleration determination.
In the operating range where GR is performed, the control means 31 is basically
The control by the control means 31 is stopped and the control valve is brought into a closed state, but during acceleration, even in the operating region where EGR is performed, the control valve 1 is controlled by the control means 31 according to the operating state.
4 and 15 opening/closing controls are performed.

A specific example of such control is shown in the flowchart of FIG. In this flowchart, when started, the throttle opening TVO is first read in step S1, and in step S2 it is determined whether the throttle opening TVO is in a region larger than a predetermined value A (for example, 1/4 of the throttle fully open). do. Judgment in step S2 is YES
If so, it is determined in step S3 whether or not it is in the EGR region,
If the determination is YES, it is further determined in step S4 whether the throttle opening change rate ΔTVO, which is the difference between the current value and the previous value of the throttle opening TVO, is larger than a predetermined value B. Based on these determinations, the following processing is performed depending on each case.

When the throttle opening degree TVO is less than or equal to the predetermined value A (determination in step S2 is NO), the process moves to step S5, the control valve opening/closing control is stopped, and the control valves 14 and 15 are
keep it closed. When the throttle opening degree TVO is larger than the predetermined value A and outside the EGR region (determination in step S3 is NO), the process moves to step S6, and the opening/closing control of the control valves 14 and 15 is performed according to the engine speed. . Also,
If it is in the EGR region (determination in step S3 is YES)
When the throttle opening change rate ΔTVO is less than or equal to the predetermined value B (the determination in step S4 is NO), the process moves to step S5 and the control valves 14 and 15 are kept closed. On the other hand, if it is in the EGR region (the determination in step S3 is YES)
) even if the throttle opening change rate ΔTVO is the predetermined value B
When the acceleration is larger (the determination in step S4 is YES),
Proceeding to step S6, the control valves 14 and 15 are controlled to open and close depending on the engine speed.

According to the device of this embodiment as described above, first of all, in the low load region, the influence on the dynamic effect of intake air is small and there is no need to increase the dynamic effect, so the control valve opening/closing control is effective. will be stopped. In addition, in high load regions outside the EGR region, the opening and closing of the control valves 14 and 15 is controlled according to the engine speed, so that the dynamic effect of intake air is enhanced in each speed region, and for example, during WOT, the dynamic effect of intake air is increased. A torque curve like line 41 in 4 is obtained, and the engine torque is increased.

In the EGR region, EGR gas introduced into the common intake passage through the EGR passage is distributed to each cylinder through the collective intake passage for each cylinder group. During steady operation in this EGR region, the control valve opening/closing control is stopped and the control valves 14 and 15 are kept closed, thereby avoiding unnecessary EGR gas flow between the two collective intake passages.
Deterioration of EGR distribution is prevented. On the other hand, even in the EGR region, during acceleration, the control valve opening/closing control is performed according to the engine speed, so the function of increasing the dynamic effect of the intake air is exerted preferentially over the EGR distribution, and the engine torque is increased. acceleration performance is ensured (line 4 in Figure 4).
(see 2).

The present invention is also applicable to engines other than the V-type engine shown in the above embodiment. Further, the structure of the intake passage and the like may be changed in design without departing from the gist of the present invention.

[0023]

[Effects of the Invention] The present invention provides an air intake system that is provided with a communication passage that communicates the collective intake passages of each cylinder group and a control valve that opens and closes the communication passage, and in which the EGR passage opens into the common intake passage. A control means is provided to open and close the control valve according to the state, and in an operating range where EGR is performed, control by the control means is stopped to close the control valve, but during acceleration, EGR is not performed. Since the control valve is provided with a control change means that causes the control means to open and close the control valve according to the operating state even in an operating region where
A function that improves EGR distribution by preventing unnecessary EGR from flowing through the communication path except during acceleration in the operating range where EGR is performed, and also enhances the dynamic effect of intake air during acceleration. It is possible to ensure acceleration performance by preferentially demonstrating the following.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an engine intake system according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of the intake system.

FIG. 3 is an explanatory diagram showing a control area.

FIG. 4 is an explanatory diagram showing torque characteristics according to engine speed when opening and closing control valves are controlled.

FIG. 5 is a flowchart showing a specific example of control of a control valve.

[Explanation of symbols]

1 Engine 2a, 2f cylinder 3a, 3b cylinder group 6a, 6f Independent intake passage 7a, 7b Collective intake passage 8 Common intake passage 12,13 Communication path 14,15 Control valve 21 EGR passage 31 Control means 32 EGR determination means 33 Acceleration determination means 34 Control change means

Claims (1)

[Claims] Claim 1: Two cylinder groups are provided, each consisting of cylinders in which the intake order is not consecutive, and independent intake passages communicating with each cylinder are collected for each cylinder group, and the collective intake passage for each cylinder group is connected to the upstream side. The two common intake passages are connected to each other by a communication passage, and a control valve is provided to open and close this communication passage, while an EGR passage for guiding EGR gas opens into the common intake passage. In an engine intake system, a control means for opening and closing the control valve according to the operating state, an EGR region determining means for determining an operating region in which EGR is performed, an acceleration determining means for determining an acceleration state of the engine, and these determinations. Based on the determination by the means, in the operating range where EGR is performed, the control by the control means is stopped and the control valve is closed; however, during acceleration, the above control is stopped even in the operating range where EGR is performed. An intake system for an engine, comprising control changing means for opening and closing the control valve according to operating conditions.