JPS60159332A - Suction device for engine - Google Patents

Abstract

PURPOSE:To aim at improvements in output of power in an engine, by making the length and area of a suction passage variable in design, and changing a suction passage area so as to cause a mean suction air flow velocity to be within an optimum range, while securing a favorable suction inertia effect upon changing the suction passage length. CONSTITUTION:In a suction passage 3 interconnected and opened to a combustion chamber 2 of each cylinder in an engine 1, there are provided with a passage length variable device 9 fitted with a cylinder member 11 slidably installed in a connecting part with a surge tank 5 and a passage area changing device 10 fitted with a moving member 12 installed in a space ranging from a suction port 7 to the inside of the cylinder member 11. And, each of actuators 13 and 14 of these aforesaid devices 9 and 10 is driven and controlled by a controlling device 15, and an engine speed signal out of an engine speed sensor 16 and a load signal out of a load sensor 17 both are inputted into this controlling device 15. With this constitution, a mean suction air flow velocity is kept up within the optimum range, while the engine speed and air column frequency are made to synchronize, thus the desired end comes to fruition.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine intake system, and particularly to an engine intake system that improves output by utilizing inertia supercharging caused by the air column vibration of the intake system and the intake period being the same. The present invention relates to an improvement of an engine intake system.

(Prior Art) Generally, the flow in the intake pipe is a so-called pulsating flow, and when the intake valve opens and the intake stroke begins, the air column in the intake pipe is accelerated due to the negative pressure generated in the cylinder and flows into the cylinder.

During this time, the cylinder internal pressure and volume change with the downward movement of the piston, and at the same time, the intake pipe internal pressure and speed also gradually change both in time and location. The pressure waves generated in the cylinder propagate through the intake pipe, are reflected at the surge tank, and return to the cylinder, and this phenomenon is repeated in the intake system. By synchronizing the frequency of the pressure change caused by the downward movement of the piston with the natural frequency of the intake system determined by the volume of the intake pipe and cylinder, an intake inertia effect can be obtained, improving volumetric efficiency and increasing output. It is well known that this can be achieved.

The natural frequency of the intake system is determined by the length and cross-sectional area of the intake passage, and the average cylinder volume during the intake period.The range of engine speeds that are synchronized with this natural frequency is widened, and the intake direction is determined by utilizing the intake inertia effect. In order to expand the upper region, various techniques have been proposed in which the length or area of the intake passage is made variable (for example, Japanese Patent Application Laid-Open Nos. 48-58214, 115819-1980, and 58-1982). -119919)
.

However, in these prior art techniques, the effect of expanding the upward range in the exit direction by utilizing the intake inertia effect is small and insufficient;
In addition, there are problems such as the need for a complicated mechanism to widen the range of change, and it is desired to obtain large tuning over a wider range with a simple structure.

For example, in a case where only the length of the intake passage is changed, the tuning range is narrow, and even if the tuning is in a tentative state, the optimum tuning can be achieved to obtain the maximum intake inertia effect at that engine speed. It does not necessarily match the conditions.

Similarly, when changing the length and area of the intake passage to obtain synchronization with the air column frequency at each engine speed, there are various length and area values that satisfy the tuning conditions at a given engine speed. However, not all conditions result in a good increase in filling efficiency.

In other words, the intake inertia effect uses air column vibration to increase the pressure of the intake boat at the end of the intake stroke to improve charging efficiency, but this charging efficiency is dependent on the size of the intake passage area (diameter) itself. However, when setting a passage area with low filling efficiency, even if you change the length of the intake passage and improve the filling efficiency due to the intake inertia effect, the filling efficiency is basically low, so this is Even if the inertia effect is improved, it is not possible to obtain a good effect on the exit direction as a whole, and it is not possible to make the most of the intake inertia effect simply by adjusting the intake inertia tuning conditions like this. It is.

(Object of the Invention) In view of the above circumstances, the present invention focuses on the intake flow velocity to expand the inertia tuning region by changing the length of the intake passage. An object of the present invention is to provide an intake device for an engine in which output is improved by changing the length and area of the passage.

(Structure of the Invention) The intake device of the present invention has variable intake passage length and variable intake passage area, and changes the intake passage area in accordance with the engine rotation speed so that the average intake flow velocity improves filling efficiency. The length of the intake passage is kept substantially constant so that it is within the optimum range, and the length of the intake passage is changed in accordance with the area of the intake passage so as to synchronize the engine speed and the air column frequency. It is something.

(Effects of the Invention) According to the present invention, by changing the intake passage length and intake passage area, the inertia tuning range is expanded and the output direction is increased in each region, so that the average intake flow velocity is within the optimum range. The area of the intake passage has been changed, which basically ensures good conditions for filling efficiency, and the length of the intake passage has also been changed to obtain a good intake inertia effect, thereby ensuring maximum intake air at all times. It is possible to obtain an inertial effect and thereby effectively increase the direction of output.

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

Embodiment 1 FIG. 1 shows a sectional front view of essential parts of a multi-cylinder engine equipped with an intake device.

An intake passage 3 that communicates with the combustion chamber 2 of each cylinder of the engine 1 is branched downstream of the surge tank 5 and is connected to each cylinder independently, and communicates with the combustion chamber 2 from the cylinder head 6 via an intake boat 7. However, a fuel injection nozzle 8 is disposed in the middle.

Further, in the intake passage 3, there is a passage length variable means 9 provided with a cylindrical member 11 slidably installed in the connecting portion with the surge tank 5, and a passage length variable means 9 that extends from the vicinity of the intake port 7 to the cylindrical member 11.
A passage area changing means 10 including a moving member 12 provided while reaching the inside of the passage area 1 is installed. The passage length changing means 9 changes the length of the intake passage by moving the cylindrical member 11 with the actuator 13, while the passage area changing means 10 moves the moving member 12 with the actuator 13.
4 to change the intake passage area, and both actuators 13 and 14 are driven and controlled by control signals from control means 15 (control unit). This control means 15 receives an engine speed signal from a speed sensor 16 and a load signal from a load sensor 17, and changes and adjusts the length and area of the intake passage in response to fluctuations in engine speed in the load range. It is something.

Note that the surge tank 5 side end 12a of the movable member 12
is rotatably attached, and is biased so that its tip comes into pressure contact with the inner surface of the cylindrical member 11, and is configured to increase or decrease the passage area through which intake air passes while allowing the cylindrical member 11 to slide. In FIG. 1, 19 is an intake valve, 20 is a cylinder block, and 21 is a piston.

The control means 15 increases the intake passage area by driving the passage area changing means 10 in accordance with the rise in engine speed, and keeps the average intake flow velocity at the intake boat 7 substantially constant within the optimum flow velocity range. At the same time, the length of the intake passage is changed and adjusted by driving the passage length variable means 9 so that the engine rotational speed and the air column frequency are synchronized in this intake passage area and an intake inertia effect is obtained. This change is greatly affected by the change in passage area, but basically the passage length is shortened in response to an increase in engine speed. In fact, since the passage area and length can be set in advance in accordance with the engine speed, the control means 15 adjusts both at the same time.

The intake inertia tuning condition is such that the intake period corresponding to the engine speed is approximately equal to the period of air column vibration corresponding to the length and area of the intake system, and the intake boat 7 immediately before the intake valve 19 closes.
The pressure of the intake passage 3 increases and the filling efficiency increases.There are infinite combinations of intake passage length and area to obtain such tuning conditions. Figure 5 shows the relationship between the volumetric efficiency and the average flow velocity in the intake passage when the length and area are changed at the same time. As can be seen from FIG. 5, when the passage length and area are changed at each engine speed, there is an optimum flow rate A at which the volumetric efficiency is maximized.

Therefore, the control means 15 outputs a control signal to the actuator 14 of the passage area changing means 10 to change the passage area so that the intake air flow velocity is maintained within the range of the optimum flow velocity A against fluctuations in the engine speed. At that point, the intake inertia tuning condition should be obtained (calculate the passage length with respect to the passage area, output a control signal to the actuator 13 of the passage length variable means 9, and adjust the intake inertia at each engine speed. It makes maximum use of the inertial effect to obtain large volumetric efficiency and improve output.

In Fig. 5, characteristic a indicated by a broken line indicates the synchronization state obtained by changing the passage length when the passage area is fixed at a certain constant value. The intake flow rate is within the range of the optimal flow rate A (the passage area is relatively wide), and good volumetric efficiency is obtained, but as the rotation speed decreases, the intake flow rate decreases, and the passage length must be changed. However, the improvement in volumetric efficiency is small. In this case, as the engine speed decreases, the passage area is reduced to increase the intake flow velocity to within the optimum range, and the passage length is changed to obtain a synchronized state in combination with the reduced passage area. It is controlled as follows.

In addition, as for the above-mentioned optimum intake flow rate, the value varies depending on the type of engine, etc., but for example, it is 40 to 60.
m/s is preferably 50 m/s. On the other hand, the tuning condition that maximizes the inspiratory inertia effect is, where the inspiratory period is ts and the air frequency is fs, the inspiratory period ts and the period of air column vibration 1/"
s are approximately equal, for example, 0.9<tsx fs<1
．． It is set within the range of 1.

Embodiment 2 FIG. 2 is a sectional front view of a main part of a multi-cylinder engine equipped with an intake system of this embodiment, and FIG. 3 is a sectional view taken along the line ■-■ in FIG. Note that even if the structure is different from that in FIG. 1, some parts with the same names are given the same reference numerals.

An intake passage 3 that communicates with the combustion chamber 2 of each cylinder of the engine 1 is provided with a surge tank 5 downstream of the throttle valve 4, and is branched downstream of the surge tank 5 and connected to each cylinder independently to inject fuel. A nozzle 8 is provided.

The surge tank 5 is formed by a casing 22 and a cylindrical rotating member 23 rotatably installed inside the casing 22, and the surge tank 5 is provided with a passage length variable means 9 for changing the passage length of the intake passage 3. It is configured. This casing 22 forms an intake manifold fastened to the cylinder head 6 of the engine 1, and extended portions of the intake passages 3 connected to each cylinder are formed along the circumferential direction of the casing 22, corresponding to each cylinder. Further, the internal space of the rotating member 23 constitutes an expansion chamber downstream of the throttle valve 4, in other words, a substantial surge tank serving as an intake air holding space, and an opening 23a is opened at the center of one end surface. This opening 23a communicates with the upstream intake passage 3 provided with the throttle valve 4 and serves as an intake inlet, and the cylindrical outer peripheral surface of the rotating member 23 partitions the internal space and the intake passage 3 on the outer periphery. Each intake passage 3 is made independent for each cylinder by being in contact with the inner wall surface of the intake passage 3 for adjacent cylinders of the casing 22. A communication port 23b on the outlet side that communicates with the intake passage 3 for each cylinder is provided on the surface of the rotating member 23, and the communication position between the internal space and the intake passage 3 changes in accordance with the rotational position of the rotating member 23. As a result, the length of the intake passage 3 from the surge tank 5 to each cylinder is made variable.

A shaft portion 23c protruding outward of the casing 22 is connected to the other end surface of the rotating member 23, and is rotatably supported by the casing 22 around the shaft portion 23c and the opening 23a. A gear 26 fixed to the output shaft of a motor 25 is meshed with an input gear 24 fixed to the end, thereby forming a driving means 27 that changes the length of the intake passage by the rotational operation of the rotating member 23. . The motor 25 is driven and controlled by a control signal from the control means 15 (control unit).

Further, in the intake passage 3 downstream of the surge tank 5, a regulating valve 28 for changing the passage area and changing the intake flow velocity is disposed at a position close to the intake boat 7, thereby forming passage area changing means 10. The regulating valve 28 is connected to an operating rod 29 and is configured to rotate as the operating rod 29 is operated by an actuator 30. The actuator is also driven and controlled by a control signal from the control means 15.

The control means 15 includes a rotation speed sensor 16 as in the previous example.
The control means 15 receives the engine speed signal from the engine speed signal and the load signal from the load sensor 17, and the control means 15 controls the drive means 27 of the passage length variable means 9 which changes the length of the intake passage in response to fluctuations in the engine speed. The passage area changing means 10 for changing the intake passage area is driven and controlled to keep the intake flow velocity substantially constant within the optimum range, and to adjust the intake period based on the air column frequency of the intake passage 3 and the engine rotation speed. The intake passage area and the intake passage length are adjusted to values that synchronize with the cycle and maximize the intake inertia effect.

The control of the passage length variable means 9 and the passage area changing means 10 by the control means 15 in this embodiment is basically the same as the previous example, but in the previous example, the passage area changing means 10 controls the intake passage downstream of the surge tank 5. Whereas the entire passage area was changed, in this example, the passage area of only a part of the intake passage 3 near the intake boat 7 is changed, and the passage area is changed by changing the passage area. The influence on the column frequency is smaller than in the previous example, and therefore, even if the regulating valve 28 of the passage area changing means 10 is operated to obtain the optimum intake flow velocity with respect to fluctuations in engine speed, the tuning condition of the intake inertia will be changed accordingly. There is little variation, and adjustment to the synchronized state for obtaining the maximum intake inertia effect is mainly performed by changing the passage length using the passage length variable means 9.

Therefore, even if the passage length is changed to obtain a synchronized state by operating the passage length variable means 9, the synchronized state will hardly change even if the passage area is changed to adjust the intake flow rate.

Embodiment 3 This example is shown in FIG. 4, and includes passage length changing means 1 similar to the previous example.
0, the movable member 31 disposed in the intake passage 3 downstream of the surge tank 5 is actuated by an actuator 33 via a link 32, and the passage area is increased not only near the intake boat 7 but also in its upstream portion. In this example, as in the first embodiment, the air column vibration is changed so that the intake flow velocity changes and the air column vibration changes as the passage area changes. As a result, the tuning range is expanded and the engine speed can be increased over a wider range of engine speeds due to the large intake inertia effect.

The rest of the structure is the same as in the previous example, and the same structures are given the same reference numerals and their explanations will be omitted.

Therefore, in each of the above embodiments, the intake flow velocity is maintained within the optimum range A by changing the passage area, and the passage length is varied to obtain the intake inertia effect, so that the intake inertia effect is utilized to the maximum. It is possible to improve filling efficiency, obtain a large intake inertia effect over a wide range, and improve output. Particularly in the low rotation range, the area of the intake passage can be reduced to maintain the intake flow velocity and improve the combustion performance within the combustion chamber.

Further, in the second and third embodiments described above, the intake passage extension part in which the passage length variable means 9 for changing the intake passage length is formed around the surge tank 5, and the rotating member 23 that rotates along the intake passage extension part. With this construction, the entire structure can be made compact, the structure can be simplified, and reliable operation can be ensured.

On the other hand, the actuation of the means for changing the intake passage area and the intake passage length is performed by a control means by a control unit that detects the engine speed as in the above embodiment, or by an actuator that operates in response to exhaust pressure. It is possible to appropriately adopt means that operates based on a signal having a correlation with the engine rotation speed, such as drive control based on the engine speed.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional front view of a main part of an engine having an intake system according to a first embodiment of the present invention, FIG. 2 is a front cross-sectional view of a main part of an engine having an intake system according to a second embodiment, and FIG. is a sectional view taken along line 11 in Fig. 2, Fig. 4 is a sectional front view of the main part of an engine having an intake device according to the third embodiment, and Fig. 5 shows the length and area of the intake passage at the same time. FIG. 7 is a characteristic diagram showing the relationship between the volumetric efficiency and the average flow velocity in the intake passage when changing the volumetric efficiency. 1...Engine 3...Intake passage 5.
... Surge tank 7 ... Intake boat 9
... Passage length variable means 10 ... Passage area changing means 15 ... Control means whistle 1! ! I 笥 4 Figure @ 5 Figure small - intake reward 1 piece

Claims (1)

[Claims] (1) In addition to providing a passage length variable means for varying the length of the intake passage leading to the cylinder, at least a passage area changing means for changing the passage area of the intake passage near the intake boat is provided to keep the average intake flow velocity within the optimum range. In order to adjust the intake passage area so as to keep it substantially constant, the passage area changing means is operated and controlled in accordance with the engine rotation speed, and the engine rotation speed and the air column vibration frequency are synchronized to obtain an intake inertia effect. MI11 for controlling the operation of the intake passage length variable means in accordance with the engine speed in order to adjust the intake passage length as shown in FIG.
An engine intake device characterized by being provided with a means.