JPH02207133A - Suction device for internal combustion engine - Google Patents

Abstract

PURPOSE:To generate high-output torque over a wide rotating range by providing multiple suction chambers for each cylinder in which opening timings of suction valves are not overlapped and selectively connecting the suction chambers in response to the operation state. CONSTITUTION:A suction device having a suction manifold body 41 partitioned into a pair of suction chambers 43 and 44 with a bulkhead 42 and a throttle body 45 connected on its upstream side is provided in a four-cylinder internal combustion engine with a valve system changing the opening/closing timing of at least one of a suction valve and an exhaust valve in response to the operation state. The suction chambers 43 and 44 are connected to combustion chambers of two cylinders 50, 53 and 51, 52 in which opening timings of suction valves are not overlapped via suction passages 54, 57 and 55, 56. Multiple openings 59 communicating both suction chambers 43 and 44 are formed on a bulkhead 42, and a switching control valve 60 is provided on each opening respectively. The switching control valve 60 is controlled in response to the transition of the rotating speed of an engine.

Description

[Detailed Description of the Invention] [Object of the Invention] <Industrial Application Field> The present invention includes a valve operating mechanism that changes the opening/closing timing of at least one of an intake valve and an exhaust valve according to operating conditions. The present invention relates to an intake system for an internal combustion engine having a large number of cylinders.

<Prior Art> Conventionally, for example, in an internal combustion engine for an automobile, there has been a switching valve mechanism that switches the opening/closing timing of at least one of an intake valve and an exhaust valve according to operating conditions such as its rotational speed. is publicly known.

According to such a mechanism, by selectively switching the valve train to a low-speed mode or a high-speed mode, high output torque can be achieved over a wide rotational speed range compared to an internal combustion engine that has only one intake/exhaust valve opening/closing timing. can be obtained.

However, in particular, patents that minimize the number of switching stages of the valve train and are characterized by high output over a wide range of rotational speeds include the speed range around the torque peak in both high and low speed ranges and the rotational speed at which the valve train is switched. The output torque may drop depending on the speed. If the rotational speed range in which such a drop in output torque occurs is the normal rotational speed range, it is likely to be noticeable as undesirable breathing of the internal combustion engine.

On the other hand, in a multi-cylinder internal combustion engine in which the intake passages of each cylinder are connected to a common intake chamber, the pulsations that occur when the intake valves of the cylinders are closed are transferred to the intake valves of the cylinders that will undergo the next intake stroke. A technique is known in which the timing of opening and closing of the intake valves of each cylinder of an internal combustion engine is synchronized to increase charging efficiency at a desired rotational speed and obtain high output torque. We focused on the fact that the frequency of the pulsations described above is different depending on whether or not they overlap with each other.

<Problem to be solved by the invention> In view of the problems of the prior art and the knowledge of the present inventor,
A main object of the present invention is to provide an intake system for an internal combustion engine that has a simple structure and can generate high output torque over a wide range from a low speed rotation range to a high speed rotation range.

[Structure of the Invention] <Means for Solving the Problems> According to the present invention, an object of the present invention is to provide a valve train in which the opening/closing timing of at least one of an intake valve and an exhaust valve is variable depending on the operating situation. The intake system for a multi-cylinder internal combustion engine is provided with a mechanism in which the opening timings of intake valves do not overlap with each other and are provided separately for each cylinder, and a plurality of intakes are communicated with each corresponding cylinder via an intake passage. and a means for selectively communicating the intake chambers with each other, and selectively causing the intake chambers to communicate with each other depending on the operating status of the internal combustion engine. This is achieved by providing

In this way, by switching the opening/closing timing of the intake/exhaust valves and switching the communication state between the two classes of air chambers, the pressure waves generated when closing the intake valve of each cylinder will cause the opening/closing of the intake valves of other cylinders. Since the rotational speed synchronized with the timing shifts and the dynamic characteristics of the intake system can be selected from four different states, the most appropriate state can be selected in each rotational speed range of the internal combustion engine. High output torque can be obtained over a speed range.

Embodiments The present invention will now be described in detail with reference to specific embodiments with reference to the accompanying drawings.

1 to 5 show a first embodiment based on the present invention, and show a part of an intake device and a valve mechanism of an internal combustion engine.

Each of the first to fourth cylinders of an internal combustion engine consisting of in-line four cylinders is provided with a pair of intake valves 1a and lb.
The camshaft 2, which rotates at a rotational speed of 2, has two low-speed cams 3a, 3b and one high-speed cam 4 for each cylinder.
The rocker shaft 8 is provided with three rocker arms 5.
~7 are pivoted in parallel to each other. Slipper surfaces 5a, 6a, and 7a that engage with the cams 3a, 3b, and 4 are formed in the intermediate portions of these rocker arms, respectively, and the free ends of the rocker arms 5.7 located on both left and right sides are fitted with lock nuts. The intake valves 1a and 1b are in contact with the stem-side free ends of the intake valves 1a and lb via tappet screws 9a and 9b fixed by 10a and 110b.

As is well known, the intake valves 1a, lb are resiliently biased in the valve closing direction by valve springs 16a, 16b via spring retainers 15a, 15b.
As the camshaft 2 rotates, it is driven to open and close via the left and right rocker arms 5.7.

The central rocker arm 6 is driven by the high-speed cam 4, and is provided at a portion of the cylinder head 11 that corresponds to the rocker arm 6, or is constantly bombarded by a lid 12 toward the sliding surface of the high-speed cam 4. energized.

Next, the valve operating switching mechanism 14 for achieving the cooperative operation of these rocker arms 5 to 7 will be explained.

As clearly shown in FIG. 2, each rocker arm 5 to 7 has a
Guide holes 17.20121 are provided which align with each other. The guide hole 17 of the rocker arm 7 located at one end is a closed blind hole, and a piston 25 is received therein. The closed end of the guide hole 17 communicates with an oil supply path 30 inside the rocker shaft 8 via a passage 32 formed in the rocker arm 7 and a boat 33 opened in the hollow rocker shaft 8 . Rocker arm 6 located in the center
The guide hole 20 is a through hole, and a piston 2 having a length substantially equal to the entire length of the guide hole 20 is installed inside the guide hole 20.
6 is accepted. A stopper 27 is received in the guide hole 21 of the rocker arm 5 located at the other end. This stopper 27 has a generally bottomed cylindrical shape, and a compression coil spring 2 is sandwiched between the inside thereof and the bottom of the guide hole 21.
8, the rocker arm 6 is constantly biased towards the central rocker arm 6.

According to this valve operating switching mechanism 14, when the oil pressure in the oil supply path 30 is low, the biasing force of the compression coil spring 28 causes the piston 25 to move into the guide hole 17, and the piston 26 to move into the guide hole 20. Since the stoppers 27 are located in the guide holes 21, the rocker arms 5 to 7 can move independently of each other. Therefore, the central rocker arm 6 is driven by the high-speed cam 4 and performs a so-called lost motion movement of simply pushing down the lifter 12 repeatedly, whereas the left and right rocker arms 5.7 are driven by the low-speed cams 3a and 3b, respectively. and opens and closes the intake valves 1a and lb in low speed mode.

When the oil pressure in the oil supply path 30 is increased, the compression coil spring 2
The piston 25 is pushed into the guide hole 20 against the spring force 8, and the piston 26 is pushed into the guide hole 21 of the rocker arm 5. Therefore, the three rocker arms 5-7 are integrally connected to each other. Here, since the cam profile of the high speed cam 4 is relatively large compared to the low speed cams 3a and 3b, the rocker arm 5.7
The intake valves 1a and lb are now driven by the central high-speed cam 4, and the intake valves 1a and 1b are driven to open and close in the high-speed mode.

On the other hand, the intake system of the internal combustion engine has three divided bodies 41a.
, 41b, 41c, and a pair of intake chambers 4 inside.
3.44 has an intake manifold body 41 having a partition wall 42, and a throttle body 45 connected to the upstream side of the manifold body. Inside the throttle body 45, passages 43a and 44a, respectively connected to the intake chambers 43 and 44, are defined by an extension 42a of the partition wall 42 to the middle part, and throttle valves 46 and 47 are formed of butterfly valves that interlock with each other. are provided in each of these passages.

One intake chamber 43 of the intake manifold body 41 is branched to provide intake passages 54 and 57 to the combustion chambers of two cylinders (first cylinder 50 and fourth cylinder 53) whose intake valve opening timings do not overlap with each other.
communicated through. In addition, the intake manifold body 41
The other intake chamber 44 similarly includes two cylinders (a second cylinder 51 and a third cylinder 52) whose intake valve opening timings do not overlap with each other.
) is communicated with the combustion chamber of the engine through an intake passage 55,56. Note that an injection nozzle 58 for injecting fuel toward the intake passages is provided at a downstream position of each of the intake passages 54 to 57.

Inside the divided body 41b of the intake manifold body 41, there are a plurality of openings 59 provided in the partition wall 42 to communicate the air chambers 43 and 44 with each other, and an opening/closing valve consisting of a butterfly valve that selectively opens and closes the openings. A control valve 60 is provided. This opening/closing control valve 60 is driven by an actuator 61, which is controlled by a control unit 62 connected to a rotation speed sensor 63 that detects the rotation speed of the internal combustion engine. Further, the control unit 62 also controls the above-mentioned valve operating switching mechanism 14 via the hydraulic controller 64.

As described above, the first to fourth cylinders 50 to 5 of the internal combustion engine
In the combustion chamber No. 3, two cylinders, the first cylinder 50 and the fourth cylinder 53, whose intake valve opening timings do not overlap with each other, communicate with the intake chamber 43 via the intake valves and intake passages 54 and 57, and the second cylinder 5
The first and third cylinders 52 communicate with the intake chamber 44 via intake valves and intake passages 55.56, and these intake chambers are connected to an air cleaner (not shown) via a throttle valve 46.47. These air chambers 43 and 44 can selectively communicate with each other through an opening 59 in which an opening/closing control valve 60 is inserted (FIG. 5).

Next, the operation procedure of the intake device based on the present invention is shown in FIGS. 1 and 4.
This will be explained with reference to FIGS.

■Low speed rotation range of the internal combustion engine, i.e. rotation speed N shown in Figure 6
In a rotation range lower than 1, the valve mechanism is set to low speed mode and the opening/closing control valve 60 is opened.

Here, the intake valves 1a and lb of the four cylinders are a first cylinder 50, a third cylinder 52, a fourth cylinder 53, a second cylinder 51, and so on.
For example, when the intake valve of the first cylinder 50 closes, the intake valve of the third cylinder 52 is already open, so the pressure wave generated when the intake valve of the first cylinder 50 is closed is the intake valve. It reaches the intake chamber 44 via the passage 54 and the intake chamber 43, and then when paying attention to the third cylinder 52, it reciprocates between the intake chamber 44 and the inside of the third cylinder 52 via the intake passage 56 and the intake valve. When the timing of entering the inside of the third cylinder 52 as a positive pressure wave (a positive multiple of the pulsation frequency that makes one cycle with two reciprocations) is synchronized with the timing when the intake valve of the cylinder closes, the Filling efficiency can be increased. This also applies to each cylinder 50-53. Therefore, the charging efficiency in each of the cylinders 50 to 53 can be increased at a specific rotational speed of the internal combustion engine that is synchronized with the pulsation frequency. As a result, a torque curve as shown in curve I in FIG. 6 appears, and the lower torque peak is utilized.

(2) When the rotational speed of the internal combustion engine increases and reaches N1, the output torque shows a slight downward trend. At this time, the on/off control valve 60
By closing the intake chambers 43 and 44, the intake chambers 43 and 44 are isolated from each other. Here, when each intake chamber 43, 44 is independent, since the intake valve opening timings of each cylinder in the same intake chamber do not overlap, for example, the pressure wave generated when the intake valve of the first cylinder 50 is closed is , the intake chamber 43 via the intake passage 54
Then, when paying attention to the fourth cylinder 53, the intake chamber 43
and the intake valve of the fourth cylinder 53 via the intake passage 57. And the timing when it reaches the intake valve as a positive pressure wave (a positive multiple of the pulsation frequency that makes one cycle with two round trips)
When the timing at which the intake and exhaust valves of the fourth cylinder 53 overlap are synchronized, the residual combustion gas in the fourth cylinder 53 is swept away, and the filling efficiency can be increased. On the contrary, the first
The filling efficiency of cylinders can be increased in the same manner. On the other hand, the filling efficiency can be similarly increased for each cylinder 51, 52 on the intake chamber 44 side.

At this time, if the intake valve opening timings of the cylinders in the same intake chamber do not overlap, the equivalent pipe length that is involved in pulsation becomes shorter by approximately the volume of the combustion chamber, compared to the case where they overlap. Therefore, the sixth
A torque curve as shown in curve H, which is different from curve I in the figure, appears, and when the rotational speed is between N1 and N2, the torque peak is utilized (N1 - N2).

(2) When the rotational speed reaches N2, close the on-off control valve 60 again. When the rotational speed is between N2 and N3 (N2<N3), the torque peak in the higher speed range of the torque curve represented by curve I is utilized again.

(2) Next, when the rotational speed N3 is reached, the valve operating switching mechanism 44 described above is switched to the high speed mode. Then, each cylinder 50~5
Since the intake valve opening/closing timing in 3 changes, the timing synchronized with the pulsation also changes, and both the torque curve represented by curve I and the torque curve represented by curve 2 shift to the high rotation range side. At this time, for example, in the case of a conventional internal combustion engine that employs only inertia intake in an internal combustion engine having a valve switching mechanism, torque curves as shown by broken lines A and B in FIG. 6 are drawn. In such a torque curve, the dashed line A
The output torque tends to decrease near the intersection of SB (rotational speed N3), that is, the switching point of the valve mechanism, but in the torque curves shown by curves I and ■, both lines have a relatively large torque peak at rotational speed N3. Because it is close to , the output torque does not drop in this speed range. When the rotational speed is between N3 and N4 (N3<N4), the torque peak of the torque curve represented by curve (2), which is the torque curve represented by curve I shifted toward the high speed range side, is utilized.

■When the rotational speed reaches N4, the on-off control valve 60 is closed again, and the torque peak in the higher speed range of the torque curve represented by curve ■, in which the torque curve represented by curve H has shifted to the high speed range side, is Utilized.

FIG. 7 is a schematic configuration diagram showing a second embodiment based on the present invention. The configuration of this embodiment is almost the same as that of the first embodiment, but in this embodiment, unlike the first embodiment, the intake passage is not bent to provide an intake chamber (the first cylinder 70 is The intake passage 74 leading to the fourth cylinder 73 and the intake passage 77 leading to the fourth cylinder 73 are combined to form an intake chamber 78, and the second cylinder 71
An intake passage 75 leading to the third cylinder 72 and an intake passage 76 leading to the third cylinder 72
The air intake chamber 79 is formed by gathering these together.

In addition, the walls separating the air chambers 78 and 79 from each other include
An opening 80 and an opening/closing control valve 81 are provided. Further, on the upstream side thereof, throttle valves 82 and 83 are provided which operate in conjunction with each other as in the first embodiment.

It goes without saying that the present invention is not limited to the above embodiments and can be applied in various ways. For example, in this embodiment, the opening/closing control valve should be opened and closed gradually to reduce shock, and as desired, when the internal combustion engine is running, the rotational speed changes rapidly, or the load is small. In some cases, the opening and closing of the on-off control valve may be prohibited in order to improve the durability of the mechanically movable parts. Further, in this embodiment, the opening/closing control valve is a butterfly valve, but it may be of any suitable shape so as not to create passage resistance in the intake passage.

[Effects of the Invention] As described above, according to the present invention, a large output torque can be obtained over a wide range of rotational speeds of an internal combustion engine with a relatively simple structure, and the effect is extremely large. .

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a part of an internal combustion engine showing a first embodiment of an intake system according to the present invention. FIG. 2 is a configuration diagram schematically showing a part of the valve train. FIG. 3 is a sectional view showing the main parts of the valve mechanism. FIG. 4 is a view taken along line IV-IV in FIG. 1. FIG. 5 is a schematic configuration diagram of the intake device in the first embodiment. FIG. 6 is a graph showing changes in the output torque of the internal combustion engine as well as switching timings of the valve train and the intake system due to changes in the rotational speed of the internal combustion engine. FIG. 7 is a diagram similar to FIG. 5, showing a second embodiment of the intake device according to the present invention. 1a, 1b... Intake valve 2... Camshaft 3a, 3b.
...Low speed cam 4...High speed cams 5 to 7...Rocker arms 5a, 6a, 7a...Slipper surface 8...Rocker shaft 9a, 9b...Tappet screws 10a, 10b...Lock nut 11. ... Cylinder head 12 ... Lifter 14 ...
Valve switching mechanism 15a, 15b... Spring retainer 16a, 16
b...Valve spring 17.20.21...Guide hole 25.26...Piston 27...Stopper 28...
・Compression coil spring 30...oil supply path 32...passage
33... Port 41... Intake manifold body 41a, 41b, 41cm/divided body 42... Partition wall 42a... Extension part 43.4
4... Intake chamber 43 a s 44 a... Passage 4
5...Throttle body 46.47...Throttle valves 50-53...1st to 4th cylinders 54-57...Intake passage 58...Injection nozzle 59.
...Opening 60...Opening/closing control valve 61...Actuator 62...Control unit!・63... Speed sensor 64... Hydraulic controller 70-73...
・1st to 4th cylinders 74 to 77...Intake passage 78.79...Intake chamber 80
...Opening 81...Opening/closing control valve 82.83
・・・Throttle valve

Claims (3)

[Claims] (1) An intake system for a multi-cylinder internal combustion engine, which is equipped with a valve operating mechanism that varies the opening and closing timing of at least one of the intake valve and the exhaust valve depending on the operating situation, the intake valves having different opening timings. a plurality of intake chambers provided separately for each non-overlapping cylinder and communicating with each corresponding cylinder via an intake passage; and means for selectively communicating the intake chambers with each other; An intake system for an internal combustion engine, characterized in that chambers are selectively communicated with each other depending on the operating status of the internal combustion engine. (2) The intake system for an internal combustion engine according to claim 1, wherein the internal combustion engine has four cylinders. (3) The intake system for an internal combustion engine according to claim 1 or 2, wherein the intake chamber is composed of two chambers.