JPS63189617A - Intake equipment of engine - Google Patents

Abstract

PURPOSE:To increase the engine output by reducing the inherent frequency of the intake pressure vibration in the low engine speed range rather than the high speed range when the engine runs under high load. CONSTITUTION:A change-over valve 12 is disposed in the secondary intake passage 7 and connected to an intake pressure frequency regulating mechanism 11. Revolution speed and load are detected by an ignition device 26 and a throttle opening sensor 20, respectively. The changeover valve 12 is closed in the low engine speed range rather than the high speed range when the engine runs under the high load, and the long equivalent length of an intake port is chosen to reduce the inherent frequency of the intake pressure vibration. The engine output may thereby increased.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an engine intake system.

(Conventional technology) Some engine intake systems perform inertial supercharging.

In such a device, as shown in Japanese Unexamined Patent Publication No. 58-115819, a pair of intake air introduction portions having different passage lengths are formed in the intake passage, and the engine rotational speed (hereinafter referred to as rotational speed) is It is known that one of the air intake introduction portions is opened by a switching valve depending on the state of the air intake. In this device, when the rotation speed is low, opening the intake introduction section with a large passage length generally yields greater output than opening the intake introduction section with a small passage length, and when the rotation speed is high, the output is greater. Opening the intake inlet with a short passage length provides greater output than opening the intake inlet with a large passage length, so when the rotation speed is low, open the intake inlet with a large passage length. When the rotational speed is high, the air intake introduction section with a small passage length is opened to control the engine so that a large output is always obtained.

(Problem to be solved by the invention) However, in the above-mentioned intake system, since a large output is always obtained, when the load is low, the throttle valve is used to avoid the need for a large output. I had to throttle the intake and reduce power.

For this reason, pumping loss increases at low loads,
Fuel efficiency was expected to decrease.

The present invention has been made in view of the above circumstances, and its purpose is to improve fuel efficiency by improving output at high loads and reducing pumping loss at low loads in an intake system that performs inertial supercharging. It is in.

(Means and operations for solving the problem) In order to achieve this object, the present invention includes an intake pressure frequency adjustment mechanism that adjusts the natural frequency of intake pressure vibration in the intake passage, and an engine rotational speed adjustment mechanism that adjusts the natural frequency of intake pressure vibration in the intake passage. A rotation speed detection means for detecting the engine load, and a load detection means for detecting the engine load.

When the load is high, the natural frequency of the intake pressure vibration is reduced in the low engine speed range compared to the high engine speed range, and when the load is low, the natural frequency of the intake pressure vibration is reversed from that at the high load. An intake system for an engine, comprising: a control means for controlling the intake pressure frequency adjustment mechanism so that the intake pressure frequency adjustment mechanism becomes

This is the configuration.

With the above configuration, due to the inertia effect, the charging efficiency improves at high loads, but at low loads, the charging efficiency decreases compared to high loads, and the degree of throttling of the throttle valve can be reduced. become.

(Example) Examples of the present invention will be described below based on the attached drawings.

In the first factor, l is the engine body which is an inline 4-cylinder engine. This engine body 1 has an intake port 2 that opens independently to each cylinder (not shown) opened on one side of the engine body 1, and an exhaust port (not shown) that opens on the other side of the engine body 1. It is considered to be a so-called cross-flow type.

A surge tank 3 is disposed on one side la of the engine body l. This surge tank 3 extends generally in the cylinder arrangement direction (direction perpendicular to the plane of the paper), and has a first surge tank 4.
and the second surge tank 5 are integrally molded. That is, the surge tank 3 made of this integrally molded product has a partition wall 3a that extends in the cylinder arrangement direction, so that the first surge tank 3 is
It is defined into a first chamber 4A for the surge tank 4 and a second chamber 5A for the second surge tank 5. The second surge tank 5 is arranged at a position slightly lower than the first surge tank 4 and at a position slightly offset in a direction away from the engine main body l.

The first surge tank 4 is individually connected to each intake port 2 via long first intake passages 6 that are independent from each other. Further, the second surge tank 5 is connected to each intake port 2 via short second intake passages 7 that are independent from each other. The first intake passage 6 is connected to the surge tank 3
It is composed of a passage portion 3b integrally molded with the intake port 2, and an intake pipe 8 connecting the passage portion 3b and the intake port 2. The first intake passage 6 generally extends from the first surge tank 4 in a direction away from one side 1a of the engine main body l, and then curves downward and is reversed approximately 180 degrees to form a surge tank. 3 and reaches the intake port 2, thereby ensuring a sufficient length.

On the other hand, the second intake passage 7 is substantially constituted by a branch pipe 8a branched from the upstream end of the intake pipe 8, and is connected to the lower end surface of the second surge tank 5 that opens downward. That is, the second surge tank 5 (second chamber 5
A) and the branch pipe 8a are configured by effectively utilizing the dead space formed by the first surge tank 4 and the first intake passage 6.

Further, in this embodiment, intake air is supplied only to the first surge tank 4, and therefore, a throttle body 9 is connected to the first surge tank 4, and the throttle body 9 is connected to the first surge tank 4. A throttle valve 10 is provided.

Reference numeral 11 denotes an intake pressure frequency adjustment mechanism of the intake passage, and the intake pressure frequency adjustment mechanism 11 includes a switching valve 12 and a switching valve 12.
It consists of an actuator 13 that opens and closes the actuator 13, an electromagnetic switching valve 14 that controls negative pressure supply to the actuator 13, and a negative pressure storage chamber 15 that serves as a negative pressure supply source. The switching valve 12 has a rotating shaft 1 rotatably supported by the intake pipe 8.
The switching valve 12 is disposed in the branch pipe 8a via a switch 6, and the switching valve 12 can open and close the branch pipe 8a. The actuator 13 is fixed to the side surface of the intake pipe 8 located at one end in the cylinder arrangement direction. The rod F of this actuator 13 is connected to the rotating shaft 16 via a link 18, and the negative pressure chamber 1 of the actuator 13
The rod 17 is displaced in accordance with the negative pressure state of the switching valve 9, and the switching valve 12 is driven to open and close. The electromagnetic switching valve 14 has three ports, one of which is connected to the negative pressure chamber 19 of the actuator 13 via a pipe 21 having an orifice 20 in the middle, and the other port is connected to the negative pressure chamber 19 of the actuator 13. It is opened to the atmosphere, and the remaining port is connected to the negative pressure storage chamber 15 via piping 22. When the electromagnetic switching valve 14 is turned on, the negative pressure chamber 19 of the actuator 13 and the negative pressure storage chamber 15 communicate with each other, and the negative pressure chamber 19
is in a negative pressure state, and as a result, the switching valve 12 is closed, and the equivalent intake pipe length is set to be a long path from the intake port 2 to the first surge tank 4 via the first intake passage 6. It is supposed to be. Solenoid switching valve 14 is OFF
When it is said that.

The atmosphere communicates with the negative pressure chamber 19 of the seventh outlet 13 so that the negative pressure chamber 19 becomes atmospheric pressure.As a result, the switching valve 12 is opened, and the equivalent intake pipe length is changed from the intake port 2 to the negative pressure chamber 19. It is supposed to be a short route leading to the second surge tank 5 via the second intake passage 7. The negative pressure storage chamber 15 is connected to the intake pipe 8 via a pipe 24.
A check valve 25 that prevents the flow of negative pressure from the negative pressure storage chamber 15 toward the intake pipe 8 is connected in the middle.

As a result, the negative pressure within the intake pipe 8 generated as the engine operates is stored in the negative pressure storage chamber 15. Further, a boost sensor 26 faces this negative pressure storage chamber 15, and a detection signal of this boost sensor 26 is inputted to a control unit 27 as a control means.

The engine is provided with an ignition device (ignition coil) 28, and an ignition pulse from the ignition device 28 is input to the control unit 27 as a rotation speed detection signal.

A throttle opening sensor 29 is attached to the throttle body 9 as an engine load detection means. The throttle opening sensor 29 has a function of detecting the throttle opening, and its detection signal is input to the control unit 27 as a load detection signal.

The control unit 27 has a function of outputting a control signal to the electromagnetic switching valve 14 based on the rotation speed detection signal and the load detection signal.

That is, when the load is high and the rotation speed is in the low rotation speed range (region a in Figure 2), the electromagnetic switching valve 14 is turned on and a long equivalent intake pipe length is selected ("Long" in Figure 2). )
, when the load is high and the rotational speed is in the high rotational speed range (region b in Figure 2), the electromagnetic switching valve 14 is turned off and a short equivalent intake pipe length is selected (the second In the figure,
On the other hand, when the load is low and the rotation speed is low (shown as "short"),
If it belongs to area C in Figure 2), the solenoid switching valve is off.
A short equivalent intake pipe length is selected as F (in Fig. 2,
When the load is low and the engine speed is in the high rotation speed range (region d in Figure 2), the electromagnetic switching valve 14 is turned on and a long equivalent intake pipe length is selected. (shown as "long" in Figure 2).

Therefore, in the above-mentioned intake system, when the load and rotational speed belong to the region a in Fig. 2, the natural frequency of intake pressure vibration is reduced compared to the case where the equivalent intake pipe length is short. The filling efficiency improves due to the inertia effect, and the third
In the figure, torque based on characteristic line A is obtained. In addition, when the load and rotation speed belong to region b in Figure 2, the natural frequency of intake pressure vibration increases compared to a long equivalent intake pipe length, and the filling efficiency improves due to the inertia effect. hand,
In FIG. 3, the torque based on characteristic line B is obtained. Therefore, during high loads, high torque can always be obtained due to inertia supercharging, and output can be improved.

On the other hand, when the load and rotational speed belong to region C in Fig. 2, the natural frequency of intake pressure vibration increases compared to the case where the equivalent intake pipe length is long, and the inertia effect causes the filling The efficiency decreases, and a torque based on characteristic line B in FIG. 3 is obtained. Therefore, this torque is smaller than the torque based on characteristic line A. However, in region C, which is a low load region and a low rotation speed region, a large output is not required, and the throttle valve lO is narrowed down to a greater extent than when output is obtained based on characteristic line A. There is no need to drop it. Therefore, it is possible to reduce the pumping loss, and it is possible to improve fuel efficiency.

In addition, when the load and rotation speed belong to region d in Figure 2, the natural frequency of intake pressure vibration is reduced compared to the case where the equivalent intake pipe length is short, and the filling efficiency is reduced due to the inertia effect. decreases, and torque is obtained based on characteristic line A. Therefore, the torque becomes smaller than the torque based on characteristic line B. However, even in the d region, which is a low load region and a high rotation region, a large output is not required as in the C region, and the throttle valve 10 There is no need to significantly reduce the output. Therefore, in this case as well, as described above, it is possible to reduce the pumping loss and improve fuel efficiency.

Further, in the above-mentioned intake device, since the orifice 20 is provided in the piping 21, the operating pressure (atmospheric pressure or negative pressure) of the actuator 13 to the negative pressure chamber 19 acts through the orifice 20. Therefore, the operating speed of the switching valve 12 is slow. As a result, the load changes between high load and low load, and the 5 equivalent intake pipe length changes (change between C area and C area, or change between b area and d area). However, the volumetric efficiency does not suddenly change, and shocks caused by load switching can be prevented. In this case, if the equivalent intake pipe length changes due to a change between the high rotation speed region and the low rotation speed region (change between the C region and the b region, or the change between the C region and the d region), Also, a delay in the operation of the switching valve 12 occurs. However, in this case, switching is performed at a switching rotation speed ro at which the respective outputs are approximately the same, and it is desirable that the operating speed of the switching valve 12 be fast. When moving from the rotation speed range to the high rotation speed range, the switching rotation speed r
The switching operation of the switching valve 12 starts at a rotational speed r1 lower than o, and when moving from a high rotational speed region to a low rotational speed region, the switching operation of the switching valve 12 starts at a rotational speed r2 higher than the switching rotational speed ro. The switching operation is now started (see Figure 2).

Furthermore, in the above-mentioned intake system, the pressure in the negative pressure storage chamber 15 is detected by the boost sensor 26, and the switching point of the switching valve 12 is corrected according to the detected pressure. As shown in FIG. 2, the switching load is changed by the control unit 27 according to the pressure state in the negative pressure storage chamber 15, and the switching conditions are always constant regardless of the magnitude of the pressure in the negative pressure storage chamber 15. can be secured. Therefore, when the negative pressure in the negative pressure storage chamber 15 is small, responsiveness can be maintained by early switching, and the driving feeling can always be constant.

Although the embodiments have been described above, the present invention includes the following embodiments.

■As a means of changing the natural frequency of the intake passage, the diameter of the intake passage is changed instead of the equivalent intake pipe length.

■Use a boost sensor, etc. as a load detection means.

(2) In place of the orifice 20, a damper or a spring may be interposed in the middle of the rod 14.

(Effects of the Invention) As described above, the present invention improves the charging efficiency at high loads due to the inertia effect, but at low loads, the charging efficiency decreases compared to the case at high loads, and the throttle Since the degree of throttling of the valve can be reduced, output can be improved during high loads, and pumping loss can be reduced during low loads to improve fuel efficiency.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the intake device according to the present invention, Fig. 2 is a diagram showing the content of switching control of the equivalent intake pipe length, Fig. 3 is a torque-revolution characteristic diagram based on the equivalent intake pipe length, and Fig. 4 is a switching load characteristic diagram of the switching valve. ll: Intake pressure frequency adjustment mechanism 27: Control unit 28: Ignition device 29: Throttle opening sensor

Claims (1)

[Claims] (1) An intake pressure frequency adjustment mechanism that adjusts the natural frequency of intake pressure vibration in the intake passage, a rotation speed detection means that detects the engine rotation speed, a load detection means that detects the engine load, and an engine under high load. The natural frequency of the intake pressure vibration is reduced in the low engine speed range compared to the high engine speed range, and the natural frequency of the intake pressure vibration is set to be opposite to that at the high load when the load is low. An intake system for an engine, comprising: a control means for controlling an intake pressure frequency adjustment mechanism;