JPS6189924A - Intake device of engine - Google Patents

Abstract

PURPOSE:To reduce a torque shock produced at the opening time of an intake air controlling valve in an engine containing said valve which can be opened only when a vehicle runs at high speed over a set value by resetting the value to a lower one and opening the intake air controlling valve by use of the new value if the vehicle is accelerated over a specified ratio. CONSTITUTION:Two intake valves 3 and 4 are provided for each of cylinders 2 and have a primary and a secondary passage 7a and 7b, respectively. The primary passage 7a contains a fuel injection valve while the secondary passage 7b contains an intake air controlling valve 11. A controller 8 senses revolutional speed 20, intake quantity 14 and opened degree 19 of a throttle valve and has an actuator 13 open and close the intake air controlling valve 11. When an engine is accelerated quickly, the controller 18 loweres a set value which is usually used for the opening time of the controlling valve 11, and opens the valve earlier. Since an intake air condition suitable for a high-speed revolution of an engine is be prepared, an intake system will be able to make an attack to any quick change in r.p.m of an engine at a quick acceleration time thereof.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to an engine in which the shape of the intake system, such as the length of the intake passage, the area of the passage, and the volume, is made variable and is switched according to the engine speed. The present invention relates to an air intake device.

(Prior art) Conventionally, in an intake system that supplies intake air to an engine, a plurality of intake passages are connected to each cylinder, and an on-off valve is attached to one of the intake passages, as shown in Utility Model Application Publication No. 57-2215, for example. A known technique is to improve the torque characteristics by controlling the opening/closing valve to close at low speeds and switching the passage surface (i) at high speeds.

In other words, in the above technology, the intake system is provided with a first state in which the torque peak is on the low rotation side and a second state in which the torque peak is on the high rotation side. As the rotational speed increases from the low rotational speed in the state of When the rotational speed is reached, the first state is switched to the second state to obtain high torque characteristics over the entire operating range.

In addition, as mentioned above, to change the shape of the engine intake system, in order to change the dynamic characteristics such as intake phosphority in response to fluctuations in engine speed, the air passage, which is an element that changes the dynamic characteristics, is There is also a technique in which the length, passage area, volume, etc. are changed to obtain dynamic characteristics suitable for each rotation range and to improve filling efficiency.

However, when the shape of the intake system is switched in response to fluctuations in engine speed as described above, there is a risk that knocking or torque shock may occur during the switching operation during sudden acceleration, resulting in a decrease in acceleration performance. In other words, knocking is likely to occur due to factors such as the air-fuel ratio of the air-fuel mixture temporarily increasing during sudden acceleration, and the ignition timing advancing earlier than the increase in torque or rotational speed. If you switch to the second state when there is a high generated torque in the first state, the torque fluctuation will be large until the generated torque in the second state increases, causing a torque shock that will affect drivability. It is something that hinders.

(Object of the Invention) In view of the above circumstances, the present invention provides an engine that improves acceleration by suppressing torque shock and eliminating knocking when switching from a first state to a second state during sudden acceleration. The purpose of this invention is to provide an intake device for the following.

(Structure of the Invention) The intake system of the present invention switches the shape of the intake system between a first state for a low speed range and a second state for a high speed range according to the engine speed. The present invention is characterized by detecting the state and correcting the set rotation speed when switching between the first state and the second state to a lower side when sudden acceleration exceeds a predetermined value. .

(Effects of the Invention) According to the present invention, during sudden acceleration, the rotation speed increases from a low rotation range to a high rotation range by correcting the set rotation speed at the time of switching from the first state to the second state to a lower value. When doing so, the intake system switches from the first state to the second state at an early stage,
The filling amount does not substantially change abruptly, and it changes along the torque characteristics of the second state from an early stage, so that the torque increases gradually without sudden torque fluctuations, and good drivability is achieved without torque shock. At the same time, knocking can be effectively prevented without temporary dilution of the air-fuel mixture.

In addition, during gentle acceleration, switching is performed at the normal set rotation speed where the torque generated in the first state and the second state match, so problems that may occur when switching is performed at an early stage similar to during sudden acceleration. That is, smooth drivability and acceleration can be obtained without causing a torque shock due to a large decrease in torque during switching.

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

Embodiment 1 FIG. 1 is an overall configuration diagram of an engine without an intake device according to an embodiment of the present invention.

Each cylinder 2 of the engine 1 has two intake boats, a first intake port 3 and a second intake port 4, and two exhaust boats 5.5.

The intake passage 7 that supplies intake air to the intake ports 3.4 is equipped with a turbo supercharger 8, and the downstream portion of the surge tank 9 is connected to the first passage 7a connected to the first intake boat 3 of each cylinder 2. , and a second passage 7b connected to the second intake boat 4. A fuel injection nozzle 10 is disposed in the first passage 7a, and an on-off valve 11 for opening and closing the second passage 7b is interposed in the second passage 7b, and each on-off valve 11 for each cylinder 2 can be operated by a common operation. This operation ll1Il112 is connected to the shaft 12 and the actuator 1
3, it is opened and closed. surge tank 9
An air flow meter 14 for detecting the intake port and a throttle valve 15 that adjusts the speed by 171 m depending on the load are installed in the intake passage 7 on the upstream side of the engine.

Further, a turbine 8a of a turbocharger 8 driven by the exhaust gas is disposed in the exhaust passage 17 connected to the exhaust boat 5.5 and leading out the exhaust gas, and is connected to the turbine 8a to direct intake air. A pressurizing blower 8b is disposed in the intake passage 7.

The operation of the actuator 13 that opens and opens the on-off valve 11 and the fuel injection by the fuel injection nozzle 10 are performed by control signals from a control device 18 (control unit). In addition to the intake air amount signal of throttle valve 1
A signal from a throttle opening sensor 19 for detecting the acceleration state based on the opening of the engine 1 and a signal from a rotation speed sensor 20 for detecting the engine rotation speed from the rotation speed of the crankshaft 6 of the engine 1 are respectively input. Ru.

In the intake system, the second passage 7b is opened by the on-off valve 11.
The first state for the low rotation range is when the on-off valve 1 is closed and intake air is supplied only through the first passage 7a.
1 and supplying intake air through the first passage 7a and the second passage 7b is the second state for the high rotation range. The actuator 13 is operated to switch between the first state and the second state at a set rotation speed according to the engine rotation speed detected by the rotation speed sensor 20, and the set rotation speed at the time of switching is determined by the throttle speed. It is changed according to the acceleration state detected by the opening sensor 19.

That is, as shown in FIG. 2A, when switching from the first state in which the on-off valve 11 is closed to the second state in which the on-off valve 11 is open, the acceleration state of the engine 1 is a slow acceleration that is less than the set value. Sometimes, it is the first set rotation speed No shown by the solid line, and when the acceleration state of the engine 1 suddenly accelerates beyond the set value, it is the second set rotation speed N1 shown by the broken line, and the second set rotation speed N1 is This value is lower than the first set rotation speed No. During sudden acceleration, the set rotation speed at the time of switching is corrected to a lower value.

As shown in FIG. 2B, the first set rotation speed No. is determined by the torque curve (E) when the intake system is in the first state and the torque curve (2) when the intake system is in the second state. The rotational speed is set to a value at which the torques generated in both states intersect and match, and the second set rotational speed N1 is set to a value lower than this.

In addition, in FIG. 2B, the curve ■ is a deceleration line.

The control device 18 outputs an open signal to the actuator 13 to open the on-off valve 11 when the engine speed increases and reaches the first set speed No. in an acceleration state other than during sudden acceleration. When accelerating rapidly, the second set rotation speed N1 is corrected to a lower rotation side, and an operation signal is output to open the opening/opening valve 11 at an earlier stage.

This provides good acceleration without causing knocking.

In the above embodiment, intake air is supplied only through the first passage 7a in the low rotation range, and since the flow velocity is high, the cylinder 2 is installed to generate a strong swirl, but the swirl is generated during sudden acceleration. If it is too strong, knocking becomes more likely to occur. However, during this rapid acceleration, the switching timing becomes earlier, and the intake air is also supplied from the second passage 7b earlier, weakening the swirl, thereby also suppressing the occurrence of knocking.

Figure 3 shows the change in intake pressure due to the operation of the turbocharger 8 during slow acceleration 1i (solid line) and rapid acceleration (broken IiI>).Point a is in the idling state and the intake pressure is negative pressure. From point b, the throttle valve 15 is opened slowly during slow acceleration, and suddenly opened during sudden acceleration.As the throttle valve 15 opens, the intake pressure rises to atmospheric pressure, and the exhaust pressure increases. Due to the increase in gas, turbocharging 'R8 is activated and the intake pressure increases in the positive pressure direction.
Eventually, boost pressure is reached. During slow acceleration, the on-off valve 11 opens at point d, and during rapid acceleration, the on-off valve 11 opens at point 0, which is earlier than this. At this time, when the opening/closing valve 11 is closed, the passage area is narrow and the intake resistance increases, resulting in a small increase in rotation of the blower 8b, whereas during sudden acceleration, the opening/closing valve 11 opens early. Blower 8b
The rate of increase in rotation becomes higher, the intake pressure increases faster, the time lag of the turbocharger 8 becomes shorter, and responsiveness during acceleration improves.

In the above embodiment, the switching setting rotation speed is set in two stages corresponding to the acceleration state f (3), but the switching setting rotation speed is controlled steplessly according to the magnitude of acceleration. It's okay.

Embodiment 2 Figure 4 shows another embodiment in which the shape of the intake system is switched between a first state for a low rotation range and a second state for a high rotation range. The system adjusts dynamic characteristics to match changes in engine speed, improving charging efficiency and torque characteristics.

Each cylinder 2°2 in the inline 6-cylinder engine 21...
The intake passage 22 connected to
It is connected to the. That is, the independent intake passages 22 of the first to third cylinders are collected in the first surge tank 23, and the independent intake passages 22 of the fourth to sixth cylinders are collected in the second surge tank 24. Furthermore, one intake passage 25.26 is connected to the first and second surge tanks 23.24 on their upstream sides, and both intake passages 25.26 collectively communicate with a merging passage 27. It is provided.

On the other hand, the first and second surge tanks 23 and 24 are in direct communication with each other through a communication passage 28.
8 is interposed with an on-off valve 29 that opens and closes the communication passage 28. This on-off valve 29 is operated by an actuator 30.
70 is opened, and a control signal from the control device 18 similar to that shown in FIG. In a high rotation range exceeding the rotation speed, switching control is performed so that the open/close valve 29 is placed in the second open state.

Then, the control device 18 detects the acceleration state of the engine 21, and when the rotation speed is set to switch to open the opening/opening valve 29 during slow acceleration below the set value, when the rotation speed is switched when the opening valve 29 is opened when the engine is accelerated at a speed exceeding the set value. This is to correct the set rotation speed to the lower rotation side.

The opening and closing of the on-off valve 29 changes the synchronized rotation speed of the dynamic characteristics associated with pressure imaging due to the influence of the air column vibration system by each surge tank 23, 24, the upstream intake passages 25', 26, and the merging passage 27. It improves charging efficiency by utilizing dynamic characteristics that match fluctuations in engine speed.

That is, when the communication length of both surge tanks 23 and 24 is lengthened, the synchronized rotation speed shifts to the low rotation side, and when it is shortened, the synchronized rotation speed shifts to the high rotation side.
9 and connect both surge tanks 23 and 24 to this communication path 2.
8 for direct communication.

Embodiment 3 FIGS. 5 and 6 show an embodiment in which the passage length of the intake system is switched between a first state for a low rotation range and a second state for a high rotation range. In these figures, structures similar to those in FIG. 1 are designated by the same reference numerals.

An intake passage 32 that supplies intake air to each cylinder 2 of the engine 31 is branched from the surge tank 9 into an independent branch passage 32a for each cylinder 2.

This branch passage 32a is curved from one side of the surge tank 9 so that the passage length becomes long, and on the other hand, the bottom of the surge tank 9 and the middle part of the branch passage 32a are short-circuited by the communication passage 33. An on-off valve 34 for opening and closing the communication passage 33 is interposed in the communication passage 33. The on-off valves 34 for each cylinder are connected by an operating shaft 35, and this operating shaft 35 is operated by an actuator (not shown) based on a control signal from a control device similar to that shown in FIG. Switching control is performed so that the on-off valve 34 is in the first closed state in the rotation range, and in the second state where the on-off valve 34 is open in the high rotation range above the set rotation speed.

The opening/closing valve 34 increases the length of the intake passage connecting the surge tank 9 and the cylinder 2 when closed and shortens it when closed, and changes the tuned rotation speed of this air vibration system. Increases intake inertia effect according to engine speed. In other words, if the passage length is made long, the tuned rotation speed will be on the low rotation side, and if it is shortened, the tuned rotation speed will be shifted to the high rotation side, so as mentioned above, the tuning speed is controlled so as to listen to the on-off valve 34 of the setting rotation instruction/communication passage 33. It is something that will be done.

Then, the control device detects the acceleration state of the engine 31,
When the on-off valve 34 is activated during slow acceleration below the set value, the set rotation speed at the time of switching is changed to 11 (toward the rotation side? +1
i It is something to correct.

Further, in this embodiment, the on-off valve 34 installed in the communication passage 33 in a5 may be configured as a switching valve that closes the branch passage 32a upstream of this communication part when listening to the communication passage 33. good.

In addition, the shape of the intake system can be changed according to the engine speed to suit each driving condition! /! In addition to the above-mentioned structures, known structures can be used as a structure for improving engine charging efficiency and torque characteristics, and the present invention is applicable to these structures.

[Brief explanation of drawings]

Fig. 1 is a structural diagram of an engine equipped with an intake system according to the first embodiment of the present invention, and Fig. 2A and B show the opening/closing timing of the 1 valve with respect to the engine rotation speed. An explanatory diagram showing the relationship between torque characteristics. Fig. 3 is an explanatory diagram showing fluctuations in intake pressure due to the operation of the 15-liter turbo supercharger during sudden acceleration and slow acceleration. Fig. 4 is a diagram showing the second embodiment. FIG. 5 is a schematic plan view of the intake device according to the third embodiment, and FIG. 6 is a cross-sectional configuration diagram taken along line vr-vr in FIG. 5. 1.21.31...Engine 7...
・Intake passage 7a...First passage 7b...
...Second passage 8...Turbo supercharging Ill
11... Opening/closing valve 13... Actuator 18... Clever II device 19... Throttle opening sensor 20...
...Rotational speed sensor 23.24...Surge tank 25.26.32...Intake passage 28.33...
...Communication path 29.34...17n Valve opening 30... Actuator'11-ta Figure 2 Figure 3 oca [lf darkness

Claims (1)

[Claims] (1) The shape of the intake system is variable between a first state and a second state, and the first state is at least under high load when the engine speed is less than the set speed, and when the engine speed is higher than the set speed. The engine intake system detects the acceleration state of the engine and switches between the first state and the second state when the engine accelerates rapidly beyond a predetermined value. An engine intake device characterized in that the engine intake device is configured to correct the amount of air to a lower side.