JPH0361007B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention improves output through the dynamic effect of intake air (intake inertia effect), for example, in a multi-cylinder engine in which each cylinder and intake expansion chamber are connected through independent intake passages. The present invention relates to an intake system for an engine. (Prior Art) Conventionally, as an intake system for the above-mentioned engine,
For example, there is a device described in Japanese Utility Model Application Publication No. 56-105626. In other words, when the intake expansion chamber and the cylinder are connected by an intake passage, and a communication valve is provided to control the opening and closing of the intake expansion chamber, and the intake inertia is utilized to increase the intake air filling efficiency, for example, the passage volume can be increased. This device is provided with a large intake passage for high speeds and an intake passage for low speeds with a small passage volume, and controls these passages by switching them according to the set rotational speed of the engine. Here, the above-mentioned intake inertia means that the negative pressure wave (pressure wave of negative pressure) generated with the start of intake is reflected at the open end to the atmosphere or the intake expansion chamber on the upstream side of the intake passage.
This is a dynamic effect of the intake air that becomes a positive pressure wave (positive pressure wave) and returns toward the intake port, and this positive pressure wave reaches the intake port just before the intake valve opens, pushing the intake air into the combustion chamber. be. By the way, the above-mentioned conventional device has the following problems. In other words, if the intake pipe volume switching setting rotation speed that maximizes the dynamic effect of intake air is fixed, the intake pipe volume will vary from engine to engine due to intake pipe manufacturing errors, and in some engines, the intake pipe volume will vary depending on the engine. As shown in the figure, there was a problem in that engine torque shock (see the thick line in the figure) occurs at the switching setting rotation. In Fig. 5, characteristic d is the torque characteristic in the low speed range when the intake pipe passage area shifts to the smaller side, characteristic e is the theoretical torque characteristic in the low speed range without variation, and characteristic f is the torque characteristic in the low speed range when the intake pipe passage area is large. The torque characteristic in the low speed range when the intake pipe passage volume shifts to the side, the characteristic x is the torque characteristic in the high speed range when the intake pipe passage volume shifts to the smaller side, the characteristic y is the theoretical torque characteristic in the high speed range without variation, the characteristic z shows the torque characteristics in the high-speed range when the intake pipe passage area is shifted to the larger side. (Objective of the Invention) This invention aims to prevent torque shock from occurring when switching the communication valve when the torque characteristics obtained from engine to engine differ due to variations in the intake pipe that occur from engine to engine. By variably controlling the opening and closing operation time of the communication valve mentioned above in response to acceleration conditions, it is possible to suppress engine torque shock at switching rotations during steady acceleration, and maintain sufficient acceleration performance during sudden acceleration. The purpose is to provide an engine intake system that can (Structure of the Invention) The present invention connects an intake expansion chamber in the middle of an intake passage through a communication passage, and communicates the intake expansion chamber with the intake passage in a specific rotation range of a predetermined engine rotation speed or higher. In this engine intake system, a communication valve for opening and closing control is disposed in the communication passage, and the position of a pressure reversal portion propagating to the intake passage is switched by opening and closing the communication valve, the engine intake system comprising: a communication valve for controlling opening and closing of the communication valve; The engine intake device is characterized by being provided with a correction means that sets the time to be longer during steady acceleration and shorter during sudden acceleration. (Effects of the Invention) According to the present invention, during steady acceleration, the above-mentioned correction means lengthens the opening/closing operation time of the communication valve,
Since the communication valve is gradually opened, the torque characteristic in the low speed range is gradually switched to the torque characteristic in the high speed range. This has the effect of suppressing engine torque shock during switching rotation during steady acceleration. Further, during sudden acceleration, the above-mentioned correction means shortens the opening/closing operation time of the communication valve and opens the communication valve quickly, so that there is no delay in operation and sufficient acceleration can be maintained. Incidentally, the torque obtained during the above-mentioned opening/closing operation depends on the projected area of the communicating valve.The larger the projected area of the communicating valve to the next high-speed side passage, the more inertia effect on the low-speed side is obtained, and as the projected area becomes smaller, The inertia effect on the high speed side can be obtained. The present invention is intended to prevent a torque shock from occurring in each engine due to a difference in torque at the time of switching the above-mentioned communication valve from open to closed, for example, at a switching point at an engine speed of 3000 rpm. However, it does not prevent torque unevenness between cylinders. (Example) An example of the present invention will be described in detail below based on the drawings. The drawing shows an intake system of an engine. In FIG. 1, an engine 1 has a cylinder block 2, a cylinder head 3, and a piston 4. The cylinder head 3 is formed with an intake port 5 and an exhaust port 6.
Each port 5, 6 has an intake valve 7 and an exhaust valve 8.
A fuel injection valve 9 is provided at the intake port 5. The above-mentioned intake port 5 is provided with an intake manifold 10.
An air cleaner (not shown) is communicated through the intake passage 11, surge tank 12, and air flow meter 13, and an intake expansion chamber 14 is integrally formed within the above-mentioned intake manifold 10.
4 and the combustion chamber 15 are configured to communicate with each other via an intake passage 11 and an intake valve 7 as appropriate. Further, a throttle valve 16 is provided behind the air flow meter 13 and in front of the surge tank 12, while a communication valve 17 for controlling opening and closing of the intake expansion chamber 14 is provided at the opening of the intake expansion chamber 14. It is set up. This communication valve 17 is connected to the engine rotation speed, for example.
Opening and closing are controlled at predetermined switching points of 3000rpm and 5000rpm, and the intake expansion chamber 14 and intake passage 11
This is a valve for switching the position of the pressure reversal section that propagates to the intake passage 11 by communicating with and blocking the intake passage 11. A correction means 18 is provided for setting the opening/closing operation time of the communication valve 17 to be longer during steady acceleration and shorter during sudden acceleration. This correction means 18 includes an actuator 19 that controls opening and closing of the above-mentioned communication valve 17, and a diaphragm chamber 20 of this actuator 19.
a supply passage 21 that supplies atmospheric pressure and negative pressure to the supply passage 21; a fixed throttle 22 disposed in the supply passage 21; a bypass passage 23 that bypasses the fixed throttle 22 of the supply passage 21; A second solenoid valve 24 serving as an on-off valve provided therein; and a first three-way switching type valve provided at one end of the aforementioned supply passage 21 and communicating selectively between the atmospheric side and the negative pressure side.
A negative pressure path 26 provided between the solenoid valve 25 and the negative pressure port of the first solenoid valve 25 and the surge tank 12 described above.
, a vacuum chamber 27 provided in this negative pressure path 26 , a check valve 28 provided in the negative pressure path 26 between this vacuum chamber 27 and the above-mentioned surge tank 12 , ROM 29 , CPU 30 , and RAM 31 . It is equipped with The CPU 30 described above drives and controls the first solenoid valve 25 and the second solenoid valve 24 according to the program stored in the ROM 29 based on the crank angle signal θ and the intake air amount signal from the air flow meter 13. In addition, the RAM 31 stores necessary data such as a set value Qc of the intake air amount and preset engine rotational speeds Nv1 and Nv2. Here, the engine speed Nvl mentioned above is, for example, 3000 rpm, and the engine speed Nv2 is,
For example, each is set to 5000 rpm. Further, the first solenoid valve 25 described above, the diaphragm chamber 20 of the actuator 19, and the communication valve 1
The relationship between the three parties with 7 is as shown in the table below.

[Table] The operation of the engine intake system configured as described above will be explained with reference to the flowchart shown in FIG. In the first step 41, the CPU 30 determines the current intake air amount Qa1 from the output of the air flow meter 13.
is read and this value is temporarily stored in the RAM 31. Next, in the second step 42, the CPU 30 reads the crank angle signal θ, and then proceeds to the next third step 43.
Then, the CUP30 calculates the current engine rotation speed R based on the above-mentioned crank angle signal θ,
This calculated value is temporarily stored in the RAM 31. Next, in a fourth step 44, the CPU 30 is already in the first
The previous crank angle signal Qa2 is subtracted from the current crank angle signal Qa1 read in step 41, and this subtracted value is compared with the intake air amount set value Qc previously stored in the RAM 31.
When steady acceleration is determined as Qa1-Qa2<Qc, the process proceeds to the fifth step 45, while when rapid acceleration is determined as Qa1-Qa2≧Qc, the process proceeds to the sixth step 46. In other words, during steady acceleration, the fifth step described above
45, the second solenoid valve 24 is controlled to close, and the first solenoid valve 24 is closed.
By gradually supplying atmospheric pressure and negative pressure from the first solenoid valve 25 shown in the figure to the diaphragm chamber 20 of the actuator 19 through the fixed throttle 22, the opening/closing operation time of the communication valve 17 is set to be long. In addition, during sudden acceleration, the sixth step 46 described above
Then, the second solenoid valve 24 is controlled to open, and atmospheric pressure and negative pressure from the first solenoid valve 25 in FIG. The opening/closing operation time of the communication valve 17 is set short. Next, in a seventh step 47, the CPU 30 updates the intake air amount Qa2 to the current intake air amount Qa1. Next, in the eighth step 48, the CPU 30
Current engine speed R and 3000rpm read from
Compare with the first set rotation speed Nv1 corresponding to
R > Nv1, current engine speed R is 3000 rpm
In the above case, proceed to the next 9th step 49, and R≦
At Nv1, when the current engine speed R is 3000 rpm or less, the process moves to the next 10th step 50. In the ninth step 49 described above, the CPU 30 compares the current engine rotation speed R described above with the second set rotation speed Nv2 corresponding to 5000 rpm, and determines that if R>Nv2,
When the current engine speed R is 5000 rpm or more, the process moves to the 10th step 50 described above, and when R≦Nv2 and the current engine speed R is 5000 rpm or less, the process moves to the next 11th step 51. In the tenth step 50 described above, the CPU 30 turns on the first solenoid valve 25 when the engine speed is below 3000 rpm and when it is above 5000 rpm.
The first solenoid valve 25 is operated to communicate with the atmosphere, and the communication valve 17 is opened. On the other hand, in the above-mentioned 11th step 51, the CPU 30
is when the engine speed is 3000rpm or more, and
When the speed is below 5000rpm, the first solenoid valve 25 is turned OFF and the first solenoid valve 2 is turned OFF.
5 on the negative pressure side, and closes the communication valve 17. The relationship between the opening and closing of this communication valve 17 and the torque is explained in the third section.
As shown in the figure. In other words, the opening characteristics of the normal communication valve 17 are as shown by the dashed line a in the figure, and the normal communication valve 1
The closed characteristic of 7 is as shown by the dotted line b in the same figure,
The above-mentioned 8th to 11th steps by the correction means 18
Through the processing in steps 48 to 51, only the characteristic portion with good torque among the above-mentioned characteristics a and b is selected, and characteristic c shown by a solid line in FIG. 3 is used. Furthermore, when the communication valve 17 is opened and closed in the tenth step 50 and the eleventh step 51, the communication valve 17 is opened and closed in accordance with the opening and closing operation time preset in the fifth step 45 and the sixth step 46. Valve 17 is opened. That is, during steady acceleration, by setting the opening/closing operation time of the communication valve 17 to be long, the communication valve 17 is gradually opened and closed, and the torque characteristic in the low speed range is gradually switched to the torque characteristic in the high speed range. In addition, the torque shock of each engine due to manufacturing errors of the intake expansion chamber 14 can be suppressed as shown by the thick line in FIG. In Fig. 4, characteristic d is the torque characteristic in the low speed range when the intake pipe passage area is shifted to the smaller side, characteristic e is the theoretical torque characteristic in the low speed range without variation, and characteristic f is the torque characteristic in the low speed range when the intake pipe passage area is large. The torque characteristic in the low speed range when the intake pipe passage area is shifted to the side, the characteristic x is the torque characteristic in the high speed range when the intake pipe passage area is shifted to the smaller side, the characteristic y is the theoretical torque characteristic in the high speed range without variation, the characteristic z shows the torque characteristics in the high-speed range when the intake pipe passage area is shifted to the larger side. Furthermore, during sudden acceleration, by setting the opening/closing operation time of the communication valve 17 to be short, the communication valve 17 can be opened and closed quickly, thereby eliminating delay in operation and maintaining sufficient acceleration. Furthermore, each element 19 limited in the embodiment section
When the correction means 18 is configured by ~24,
A structure for variable control of opening/closing operation time can be easily formed.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a system diagram showing an engine intake system, Fig. 2 is a flowchart, Fig. 3 is a schematic characteristic diagram showing the relationship between torque and engine speed, and Fig. 4 is a diagram showing an engine intake system. The figure is a rotational speed-torque characteristic diagram of the engine at the time of steady acceleration and at the time of switching the communication valve, and FIG. 1...Engine, 11...Intake passage, 14...
Intake expansion chamber, 17... Communication valve, 18... Correction means, 19... Actuator, 20... Diaphragm chamber, 21... Supply passage, 22... Throttle, 23
...Bypass passage, 24...Second solenoid valve.

Claims (1)

[Scope of Claims] 1. In order to connect an intake expansion chamber in the middle of the intake passage via a communication passage, and to communicate the intake expansion chamber with the intake passage in a specific rotation range of a predetermined engine rotation speed or higher. , an engine intake system in which a communication valve for controlling opening and closing is disposed in the communication passage, and the position of a pressure reversal portion propagating to the intake passage is switched by opening and closing the communication valve, the opening and closing operation time of the communication valve being , an engine intake system equipped with a correction means that is set longer during steady acceleration and shorter during sudden acceleration. 2. The correction means includes an actuator that controls the opening and closing of the communication valve, and an atmospheric pressure in a diaphragm chamber of the actuator.
An engine according to claim 1, comprising a supply passage for supplying negative pressure, a throttle disposed in the supply passage, and an on-off valve interposed in a bypass passage that bypasses the throttle of the supply passage. Intake device.