JPH0745809B2 - Engine intake system - Google Patents

Description

The present invention relates to an intake device for an engine.

(Prior Art) In recent years, there are many engines that utilize the dynamic effect of intake air to improve supercharging, that is, volumetric efficiency. Inertial supercharging is one of the dynamic effects of this intake air. In this inertial supercharging, the negative pressure wave from the cylinder in the intake stroke is inverted into a positive pressure wave by a surge tank or the like, and supercharging is performed by the intake pushing action by the positive pressure wave.

This inertia supercharging satisfies the tuning condition only at a predetermined engine speed. For this reason, in order to change the tuning condition, a timing valve that is operated in synchronization with the engine output shaft is provided in the intake passage, and this intake valve is used to substantially change the intake start timing. (See JP-A-55-107018).

However, since inertia supercharging is only for inverting the negative pressure wave as it is as a positive pressure wave to perform the intake pushing, it has a great effect in a considerably high speed range, but has a low rotation speed. There is a limit to the sufficient volumetric efficiency improvement in the region.

Another of the dynamic effects of intake is resonance supercharging. This resonance supercharging connects the resonance passage to the collecting portion where a plurality of cylinders are collected through the branch intake passage,
The air column in the resonance passage is vibrated by using a continuous negative pressure wave due to the periodic opening and closing of the intake port as an exciting force. Then, when the vibration resonance occurs, the amplitude becomes maximum, and a large supercharging is performed. In other words, the resonance supercharging is equivalent to the one-degree-of-freedom vibration system, and the negative pressure wave generated by opening and closing the intake port acts as an exciting force, and the resonance causes the amplitude of the negative pressure wave to be increased. Since a larger amplitude can be obtained, it is possible to obtain a far greater effect than the inertial supercharging in improving the volumetric efficiency in the low speed range.

By the way, in a multi-cylinder engine, the cylinders often have an overlap in the intake port open period. If this overlap, especially a large overlap,
The so-called inter-cylinder interference reduces the effect of resonance supercharging. Therefore, as shown in Japanese Patent Publication No. 60-14169, a plurality of cylinders are divided into a first cylinder group and a second cylinder group for each cylinder whose ignition order is not adjacent to each other, and an intake passage is provided for each cylinder group. While having a collecting portion and a resonance passage communicating with the collecting portion, a switching valve that connects and disconnects the collecting portions is provided, and each collecting portion and the cylinder group are
Connection is made via a long branch intake passage for inertial supercharging. Then, at the time of low rotation, both collecting parts are shut off to perform resonance supercharging independently for each cylinder group, while at the time of high rotation, both collecting parts are communicated with each other to perform inertia supercharging. ing.

(Problems to be Solved by the Invention) By the way, how to secure low-speed torque is an important issue during an internal combustion period as represented by a gasoline engine and a diesel engine. It would be preferable to utilize salary. Particularly, in the case of resonance supercharging, unlike the case of inertia supercharging, it has an advantage that a long branch intake passage is not required for each cylinder, which is also preferable in terms of downsizing the intake system. .

The present invention has been made in consideration of the above circumstances,
Assuming that the engine is a multi-cylinder engine that has an overlap in the intake port opening period, resonance supercharging is used to improve torque in the lower engine speed range and to improve the torque in the higher engine speed range. An object of the present invention is to provide an intake system for an engine capable of improving the torque by feeding.

(Means and Actions for Solving Problems) In order to achieve the above-mentioned object, the present invention has the following configuration. That is, in a multi-cylinder engine having an overlap in the intake port open period between cylinders, the multi-cylinder is divided into a plurality of minority cylinder groups with a small overlap in the intake port open period, and the intake passage is In addition, each has an independently provided collecting portion and a resonance passage continuing to the collecting portion, and the intake passage has a non-divided state in which the collecting portions communicate with each other and a divided state in which the collecting portions are shut off from each other. And an intake period switching means for switching between a retarded state in which the intake period is shortened in each cylinder and an advanced state in which the intake period is larger than the retarded state. Control means for controlling the switching between the division switching means and the suction period switching means is provided with the number of revolutions as a parameter.

As described above, in the present invention, when the engine speed is low, the non-divided state and the retarded state can be used to perform resonance supercharging by utilizing the resonance passage common to all the cylinders, that is, between all cylinders. A large torque improvement can be obtained on the low rotation side. That is, assuming that the engine speed is No and the natural frequency of the intake system is fo, and the cylinder number is a, the tuning condition for resonance supercharging is:
In the case of a 4-cycle engine, No = 120fo / a, and in the case of a 2-cycle or rotary piston engine, No = 60fo / a. That is, if the resonance passages have the same length (fo is the same), the larger the number of cylinders a involved in resonance supercharging, the more the engine speed at which the resonance supercharging tuning condition is satisfied.
No becomes smaller. For example, in a 6-cylinder engine, 3
When divided into two minority cylinder groups for each cylinder, the engine speed at which resonance supercharging is achieved with 6 cylinders is 1/2 of the engine speed at which resonance supercharging is achieved with 3 cylinders.

In addition to this, when the engine speed is low, the intake pressure is delayed and the negative pressure wave itself, which is the exciting force for obtaining resonance supercharging, becomes large, making resonance supercharging, that is, a large torque improvement more effective. Can be obtained.

On the other hand, when the engine is running at high speed, the engine is brought into a divided state and an advanced state, and resonance supercharging is performed for each minority cylinder group. At this time, as is already clear from the above description, even if the resonance passages have the same length, the number of cylinders involved in resonance supercharging becomes smaller than that at low rotation, so that each cylinder is set in the advanced state. In addition to ensuring a sufficient intake period, the torque can be improved by resonance supercharging even at this high rotation speed.

Of course, in the present invention, since the resonance supercharging can be obtained when the engine speed is low or high, the length of the branch intake passages that are individually connected to the respective cylinders is made particularly long as in the case of obtaining the inertia supercharging. Since it is not necessary, it does not prevent the engine from becoming compact. Moreover, by changing the number of cylinders involved in resonance supercharging, resonance supercharging can be obtained over a wide range of engine speeds. This is advantageous in terms of downsizing as compared with the case where the tuning condition for supercharging is changed.

Embodiments Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1 showing the first embodiment of the present invention, E1 is a four-cycle reciprocating engine body, and in the embodiment, a V-type 6
It is for cylinders. That is, the engine body E1 has a pair of left and right bank portions 1L and 1R that are V-shaped, and each is parallel to the crankshaft 2 and has a left bank portion 1L.
Three cylinders 3L of No. 3, No. 5 and No. 3 are constructed, and three cylinders 3R of No. 2, No. 4, No. 6 are constructed in the right bank section 1R. Intake port 4L (4R) of each cylinder 3L (3R)
Are opened toward the V-bank central space V, while the exhaust ports 5L (5R) are opened on the side opposite to the V-bank central space V, which is a so-called cross-flow type.

In the central space V of the V bank, a pair of left and right collecting pipes 11L and 11R that extend in parallel with the crankshaft 2 and serve as intake collecting portions.
Is provided. To the left side collecting pipe 11L, three left cylinders 3L (the intake ports 4L thereof) are independently connected via short branch intake pipes 12. Similarly,
To the right collecting pipe 11R, the three right cylinders 3R (the intake ports 4R thereof) are independently connected via a short branched intake pipe 12R. The ignition order is, for example, 1
It is set in the order of No. → 6 → 3 → 4 → 5 → 2. That is, the three cylinders 3L in the left bank portion 1L constitute a left minority cylinder group in which the open periods of the intake ports 4L do not overlap, as shown in FIG. 3 (a). Similarly, the three cylinders 3R in the right bank 1R constitute a right minority cylinder group in which the open periods of the intake ports 4R do not overlap, as shown in FIG. 3 (b).

The intake passage I including both the collecting pipes 11L and 11R has two resonance passages 13L and 13R on the left and right sides, one common intake passage 14 and one pressure reversing portion 15 for resonance supercharging having a large volume. And.

The right resonance passage 13L connects the left collecting pipe 11L and the pressure reversing portion 15, and the right resonance passage 13R connects the right collecting pipe 11R pressure reversing portion 15. Further, the common intake passage 14 has its downstream end connected to the pressure reversing portion 15, and an air cleaner 16 and an air flow meter 17 are connected to the common intake passage 14.

Split switching means for connecting and disconnecting the two collecting pipes 11L and 11R
In order to configure X1, the left and right resonance passages 13L and 13R are communicated with each other near the collecting pipes 11L and 11R via a short communication passage 18, and an on-off valve 19 is arranged in the communication passage 18. An on-off valve 20 is provided in either one of the left and right resonance passages 13L and 13R (13R in the embodiment), slightly upstream of the division switching means X1. Furthermore, the passage for resonance
In 13L and 13R, the throttle valves 21 which are interlocked so as to have the same opening degree on the downstream side of the division switching means X1.
L and 21R are arranged.

Timing valves 31L and 31R for adjusting the suction periods of the cylinders 3L and 3R are formed in the left and right collecting pipes 11L and 11R. Since the left and right timing valves 31L and 31R have substantially the same configuration, attention is paid to the left timing valve 31L, and for the right timing valve 31R, the reference sign "R" is used instead of the reference sign "L". The duplicated description will be omitted.

A housing 32L of the timing valve 31L also serves as a bottomed cylindrical collecting pipe 11L, and a rotor 33L rotatably arranged inside the timing valve 31L also has a bottomed cylindrical shape. That is,
The rotor 33L has an opening portion at one end facing the downstream end of the resonance passage 13L as the inflow port 34L, and the intake air is filled therein. An outlet 35L is formed on the side wall of the rotor 33L for each branch intake passage 12L.

The rotors 33L and 33R of the timing valves 31L and 31R are rotationally driven by the crankshaft 2 via the advance mechanism S. The advance mechanism S includes a shaft portion 33L protruding from one end of the rotor 33L.
-The first helical gear 41 integrated with a and the shaft portion 33L-
It has a second helical gear 42 integrated with an intermediate shaft 42 arranged in series with a, and an adjusting piece 44 meshed with both the helical gears 41, 42. The intermediate shaft 42 and the crankshaft 2 are linked by a transmission mechanism 45 including a toothed pulley and a timing belt. The rotors 31L and 31R are interlocked by gears 46 and 47 so that they rotate at the same speed and in opposite directions. The crankshaft 2 and the intermediate shaft 42 have a rotation ratio of 2: 1. When the crankshaft 2 is rotated,
Both rotors 33L and 31R are connected to the crankshaft 2 via the advance mechanism S.
It is rotated at half the speed of. And the adjustment (advance angle adjustment) of the rotation phase of the rotors 33L and 33R with respect to the crankshaft 2 is
This is done by moving the adjusting piece 44 from side to side in FIG.

In FIG. 1, U is a control unit to which an engine speed signal from a sensor 51 is input.
Further, the control unit U outputs to the actuator 52 for moving the adjustment piece 44 to the left and right and the actuators 53, 54 for driving the opening / closing valves 18, 20.

Here, the open periods of the intake ports 3L and 3R are set as shown in FIG. That is, the ignition order is the order of 1st → 6th → 3rd → 4th → 5th → 2nd, and the arbor lap “OR” during the intake port opening period between the cylinders is extremely large as is well known. Is set as. Then, the intake port open period in the minority cylinder group 3L of the left bank portion 1L and the intake port open period in the minority cylinder group 3R of the right bank portion 1R are set such that the overlap is exactly "zero". . Also, the timing valve 31L (31
R) has an outlet 35L (35R) whose branch intake passage 12L (12
R), the opening and closing timing is set as shown by the broken line in FIG. 2 in the retarded state,
The above-mentioned overlap "OR" is made small, such as "OR '". In the advanced state, the third
As shown in Figure (a) and Figure 3 (b), intake port 4L
It is designed to almost coincide with the open period of (4R). In this way, the timing valves 31L and 31R and the advance mechanism S are
It constitutes the inhalation period switching means X2.

In the above configuration, the opening / closing valve 19 is opened, the opening / closing valve 20 is closed, and the timing valve is opened at the time of low rotation.
31L and 31R are in the retarded state (the inhalation period is set as the shaded portion in FIG. 2). As a result, all six cylinders 3L and 3R are
A multi-cylinder (six cylinders) utilizing the pressure reversing section 15 is used, in which the collecting pipes 11L and 11R are communicated with each other via a communication passage 18 as a common collecting portion, and the left resonance passage 13L is a common resonance passage. ) Resonance supercharging is performed. Of course, at this time, by reducing the inter-cylinder interference and increasing the generation of the negative pressure wave as the exciting force, the resonance supercharging is effectively performed and the engine rotation condition that satisfies the resonance tuning condition is satisfied. Since the number is multi-cylinder (six-cylinder) resonance, it can be set to an extremely low rotation range. At this time, closing the on-off valve 20
This is because the number of resonance passages is reduced to more effectively exhibit resonance supercharging, and the on-off valve 20 may be omitted.

On the other hand, at high rotation speed, the on-off valve 20 is opened and the on-off valve
19 is closed, and the timing valves 31L and 31R are brought into the advanced state shown in FIGS. 3 (a) and 3 (b). The actual intake period in each cylinder at this time is substantially the same as the open period of the intake port 6, as shown by the hatching in FIG. This ensures a sufficient inhalation period, while maintaining the left and right bank parts.
Resonance supercharging is performed independently for each of the three cylinders 3L and 3R of 1L and 1R. Of course, at this time, the resonance tuning rotation speed is shifted to the high rotation side because the resonance is in the minority cylinder.

The state of the above-mentioned resonance supercharging is collectively shown in FIG. It should be noted that when the engine speed becomes considerably higher than the engine speed for obtaining the resonance supercharging of the small number of cylinders, it is preferable to reopen the opening / closing valve 19 in order to improve the torque.

In addition, FIG. 5 shows that the timing of opening / closing switching of the opening / closing valves 18 and 20 and the timing of advancing switching of the timing valves 31L and 31R are slightly shifted so that the valley of the torque obtained by the multi-cylinder resonance and the minority-cylinder resonance can be obtained. It shows that it can be filled.

FIG. 6 shows a second embodiment of the present invention. The same components as those in the above embodiment are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, the case where the invention is applied to a Wankel type two-cylinder rotary piston engine is shown. That is, the engine body E2 has a side housing 82, a rotor housing 83, an intermediate housing 84, a rotor housing 85, and a side housing 86, which are sequentially connected from one end side to the other end side of the output shaft (eccentric shaft) 81. A rotor (not shown) is housed in each of the rotor housings 83 and 85. The left side of FIG. 6 is the front cylinder R1, and the right side is the rear cylinder R2.

Two intake ports 87, 88 of primary and secondary are opened in each rotor housing 83, 85,
The primary intake port 87 is in the intermediate housing 84 and the secondary intake port 88 is in the side housing 82 or 86.
Is formed in. The timings of opening and closing the primary and secondary intake ports 87 and 88 by the rotor are the same.

In the present embodiment, the branch intake passages 91, 92 of the front cylinder R1 are connected to the rear collecting portion 93L that once merges on the upstream side. Similarly, the branch intake passages 91 and 92 of the rear cylinder R2 are also connected to the rear collecting portion 93R that is once merged on the upstream side. Both of these collection parts 93L
And 93R are formed by partitioning the inside of the tank 93 with a partition wall 93a. The partition switching means X1 for connecting and disconnecting the two collecting portions 93L and 93R is configured in the partition wall 93a. Also, a timing valve for adjusting the inhalation period
61 is provided at a portion where the respective branch intake passages 91 and 92 merge. The timing valve 61 has a housing 62 and a rotor 63 rotatably arranged in the housing 62. The housing 62 includes a collecting portion 93L (93L) for each cylinder.
The suction port 64 is always connected to the R) side, and the outflow port 65 is always connected to the intake ports 87 and 88. Further, the rotor 63 is configured such that a communication port 66 penetrating in a radial direction for each cylinder is opened in the cylindrical member.

Here, the opening / closing timing of the intake ports 87, 88 opened / closed by the rotor is set as shown in FIG. 7, and as is known, between the front and rear cylinders R1 and R2 is large during the intake port open period. It has an overlap "OR". On the other hand, when the timing valve 61 is retarded as shown in FIG. 7, the overlap is effectively "zero" as shown by "OR '". That is, the substantial suction periods in the front and rear cylinders R1 and R2 are the shaded portions in FIG. Of course, when the timing valve 61 is advanced,
As shown in FIGS. (A) and (b), the intake period is substantially the open period of the intake ports 87, 88.

In the above-described configuration, the opening / closing valve 19 is opened and the timing valve 61 is retarded (7th time) at low rotation and high load.
(State in the figure), a multi-cylinder (two cylinders) in which the collecting portions 93L and 93R with the front and rear cylinders R1 and R2 and the resonance passages 13L and 13R are common
Resonance supercharging is performed. In the rotary piston engine, even if the overlap is eliminated in this way, the opening period of the intake port 87 or 88 is originally the rotation angle of the output shaft 81.
Since it is extremely large at 270 °, a sufficiently long suction period can be secured even if this overlap is eliminated, and the volume efficiency at low rotation and high load is extremely higher than that of the reciprocating type. To be big.

On the other hand, when the engine speed is high, the on-off valve 19 is closed and the timing valve 61 is advanced (states shown in FIGS. 8 (a) and 8 (b)), so that the front and rear cylinders R1 and R2 are independently resonantly excited. Salary is paid.

In the above embodiment, the advancing mechanism S is provided for the timing valve 31L, 31R or 61 to adjust the intake period of each cylinder according to the engine speed. However, the bypass passage bypassing this timing valve is used. May be provided for each cylinder, and the intake period may be changed by opening and closing the on-off valve provided in the bypass passage according to the engine speed.

(Effects of the Invention) As is clear from the above description, the present invention effectively exhibits resonance supercharging even in a lower engine speed range in a multi-cylinder engine having an overlap in the intake port opening period between cylinders. , The torque can be greatly improved.

Further, since the number of cylinders involved in resonance is changed according to the engine speed, such as multi-cylinder resonance and minority-cylinder resonance, a wider engine speed range is provided at low speed and high speed. Resonance supercharging can be done across.

Of course, since the tuning condition for resonance supercharging is changed by adjusting the number of cylinders, as compared with the case where this tuning condition is changed by changing the length of the resonance passage,
The intake system can be made compact.

[Brief description of drawings]

1 to 5 show a first embodiment of the present invention. FIG. 1 shows a simplified overall system diagram, and FIG. 2 shows an intake period when performing multi-cylinder resonance supercharging at low rotation speed. A graph, FIG. 3 is a graph showing an intake period when a small number of cylinders are resonantly supercharged, and FIGS. 4 and 5 are graphs showing the relationship between the operating mode, torque, and engine speed in the embodiment shown in FIG. It is a graph. 6 to 8 show a second embodiment of the present invention, FIG. 6 is a simplified overall system diagram, FIG. 7 is a graph corresponding to FIG. 2, and FIG. 8 corresponds to FIG. It is a graph. E1: Engine body 3L, 3R: Cylinder 4L, 4R: Intake port 11L, 11R: Collecting pipe (collecting part) 12L, 12R: Branch intake pipe 13, 13R: Resonance passage 18: Communication passage 19: Open / close valve 31L, 31R : Timing valve 51: Revolution sensor 52, 53, 54: Actuator 61: Timing valve R1, R2: Cylinder 87, 88: Intake port 91, 92: Branch intake passage 93L, 93R: Collecting part S: Advance mechanism X1: Split switching means X2: Inhalation period switching means U: Control unit

Claims (2)

[Claims] 1. A multi-cylinder engine having an overlap in an intake port open period between cylinders, wherein the multi-cylinder is divided into a plurality of minority cylinder groups having a small overlap in the intake port open period, and an intake passage has the minority. Each cylinder group has an independently provided collecting portion and a resonance passage communicating with the collecting portion, and the intake passage has a non-divided state in which the collecting portions communicate with each other and the collecting portion is cut off from each other. And a suction period switching unit for switching between a retarded state in which the suction period is shortened in each cylinder and an advanced state in which the suction period is longer than the retarded state. A control means for controlling switching between the division switching means and the suction period switching means is provided with the engine speed as a parameter. . 2. The intake valve according to claim 1, wherein the intake period switching means is composed of a timing valve provided in the intake passage, and the timing valve is delayed from the intake port opening timing in the retarded state. An intake device for an engine, wherein the intake device is opened, and in the advanced state, the open period is substantially the same as the open period of the intake port.