JP2740664B2 - Intake device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] <Industrial Application Field> The present invention comprises a multi-cylinder number of cylinders having a valve operating mechanism in which the opening / closing timing of an intake valve is made variable in accordance with an operating condition. The present invention relates to an intake device for an internal combustion engine.

<Prior Art> Conventionally, for example, in an internal combustion engine for a vehicle, a switching valve mechanism that switches the opening / closing timing of an intake valve in accordance with an operating condition such as a rotation speed thereof has been known. According to such a mechanism, by selectively switching the valve operating mechanism to the low speed mode or the high speed mode, a high output torque can be obtained over a wide rotation speed range as compared with an internal combustion engine having only one intake / exhaust valve opening / closing timing. Can be obtained.

However, especially when the number of switching stages of the valve train is to be minimized and high output is to be obtained over a wide range of rotational speeds, switching of the speed range and the valve train before and after both resonance torque peaks in the high speed and the low speed ranges. The output torque may drop at a given rotation speed. If the rotational speed range in which such a drop in output torque occurs is the normal rotational speed range, the internal combustion engine is likely to stand out as an undesirable breath.

On the other hand, in a multi-cylinder internal combustion engine in which the intake passage of each cylinder communicates with a common intake chamber, the pulsation generated when the intake valve of a certain cylinder is closed is reduced by the pulsation of the intake valve of the cylinder that will be the next intake stroke. A technique is known in which the filling efficiency at a desired rotational speed is increased by synchronizing with the opening / closing timing to obtain a high output torque, but the present inventor has proposed such an opening / closing timing of an intake valve of each cylinder of an internal combustion engine. It is noted that the frequency of the above-mentioned pulsation is different between the case where the pulsation overlaps and the case where the overlap does not occur.

<Problems to be Solved by the Invention> In view of the problems of the related art and the knowledge of the inventor, the main object of the present invention is to provide a simple structure that extends from a low-speed rotation range to a high-speed rotation range of an internal combustion engine. It is an object of the present invention to provide an intake device for an internal combustion engine capable of generating a high output torque over a range.

[Constitution of the Invention] <Means for Solving the Problem> According to the present invention, the operation state is switched between a low-speed mode and a high-speed mode in order to change the output torque of the engine according to the operating condition. A valve mechanism, an intake valve that is controlled to be opened and closed by the valve mechanism, and a cylinder in which the opening timings of the intake valves do not overlap with each other to connect between the intake valve ports of the intake valve and the plurality of intake chambers. A separately provided intake passage, and an open / close valve for selecting communication / non-communication between the plurality of intake chambers. The open / close valve uses an output torque due to inertial supercharging in an open state and a closed state in an open state. An intake device for an internal combustion engine adapted to utilize output torque due to resonance supercharging, wherein each of said intake chambers, when communicated with each other, fills a region of low resonance torque in each of said modes. Has characteristics The valve operating mechanism switches between a low-speed mode and a high-speed mode at a rotational speed at which the inertia torques in the respective modes are substantially equal to each other. Opening / closing at a rotational speed at which an inertia torque and a resonance torque substantially coincide with each other, and maintaining an open state at a rotational speed at which each mode is switched. Is achieved by

<Operation> As described above, the portion where the torque decreases before and after the resonance torque peak is filled by the inertia torque peak obtained by opening the on-off valve and communicating each intake chamber with each other, and the on-off valve is switched at the time of switching between the modes. Opening and using the inertia torque, by switching the mode at the rotation speed near the intersection of the inertia torque of the low-speed mode and the inertia torque of the high-speed mode, so that the inertia torques in each mode are continuous without shock. Not only a drop in output torque at the time of mode switching, but also a step in torque, that is, a so-called torque shock, is eliminated, and a high output torque can be obtained over a wide speed range of the internal combustion engine.

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

1 to 5 show a first embodiment according to the present invention, and show a part of an intake device and a valve train of an internal combustion engine. Each of the first to fourth cylinders of the in-line four-cylinder internal combustion engine is provided with a pair of intake valves 1a and 1b, and a half of a crankshaft.
The camshaft 2 which rotates at a rotational speed of 2 is provided with two low-speed cams 3a and 3b and one high-speed cam 4 for each cylinder, and the rocker shaft 8 has three rocker arms 5-7. Are pivoted in parallel with each other. In the middle of these rocker arms, slipper surfaces 5 engaging with the cams 3a, 3b, 4 are provided.
a, 6a and 7a are formed respectively, and the free ends of the rocker arms 5 and 7 located on both left and right sides are lock nuts.
It comes into contact with the stem-side free ends of the intake valves 1a, 1b via tappet screws 9a, 9b fixed by 10a, 10b.

As is well known, the intake valves 1a, 1b are connected to valve springs 16a, 1b via the spring retainers 15a, 15b.
6b, it is resiliently urged in the valve opening direction, and is driven to open and close via left and right rocker arms 5 and 7 as the camshaft 2 rotates. The center rocker arm 6 is driven by the high-speed cam 4, but is constantly repelled toward the sliding contact surface of the high-speed cam 4 by a lifter 12 provided in a portion of the cylinder head 11 corresponding to the rocker arm 6. Being energized.

Next, a description will be given of the valve train switching mechanism 14 for achieving the cooperative operation of the rocker arms 5 to 7.

As best shown in FIG. 2, each of the rocker arms 5 to 7 is provided with guide holes 17, 20, and 21 which are aligned with each other. The guide hole 17 of the rocker arm 7 located at one end is a closed blind hole, in which a piston 25 is received. The closed end of the guide hole 17 communicates with an oil supply passage 30 inside the rocker shaft 8 through a passage 32 formed in the rocker arm 7 and a port 33 opened in the hollow rocker shaft 8. The guide hole 20 of the rocker arm 6 located at the center is a through hole, in which a piston 26 having a length substantially equal to the entire length of the guide hole 20 is received.
A stopper 27 is received in the guide hole 21 of the rocker arm 5 located at the other end. The stopper 27 has a substantially bottomed cylindrical shape, and is constantly resiliently biased toward the center rocker arm 6 by a compression coil spring 28 interposed between the inside thereof and the bottom of the guide hole 21.

According to the valve switching mechanism 14, when the oil pressure in the oil supply path 30 is low, the piston 25 is placed in the guide hole 17 and the piston 26 is placed in the guide hole 20 by the urging force of the compression coil spring 28. Since the stoppers 27 are respectively located in the guide holes 21, the rocker arms 5 to 7 can move independently of each other. Accordingly, the center rocker arm 6 is driven by the high-speed cam 4 and performs a so-called lost motion motion that only pushes down the lifter 12, while the left and right rocker arms 5 and 7 are driven by the low-speed cams 3a and 3b, respectively. Then, the intake valves 1a and 1b are driven to open and close in a low-speed mode.

When the oil pressure in the oil supply path 30 is increased, the compression coil spring 28
The piston 25 protrudes into the guide hole 20 and the piston 26 protrudes into the guide hole 21 of the rocker arm 5 against the spring force. Therefore, three rocker arms 5
7 are integrally connected to each other. Here, low speed cam 3
Since the cam profile of the high-speed cam 4 is relatively large with respect to a and 3b, the rocker arms 5 and 7 are also driven by the central high-speed cam 4, and the intake valves 1a and 1b are opened and closed in the high-speed mode. It will be driven.

On the other hand, the intake device of the internal combustion engine has three divided bodies 41.
a, 41b, 41c and a pair of intake chambers 43, 44 inside.
An intake manifold body 41 formed with a partition wall 42,
A throttle body 45 connected to the upstream side of the manifold body. Inside the throttle body 45,
Passages 43a, 44a respectively connected to the intake chambers 43, 44 are formed up to an intermediate portion by an extension portion 42a of the partition wall 42, and throttle valves 46, 47 formed of butterfly valves which are interlocked with each other are provided in these passages, respectively. I have.

One intake chamber 43 of the intake manifold body 41 is branched into two cylinders (first cylinders) in which the intake valve opening timings do not overlap each other.
50, the combustion chamber of the fourth cylinder 53) is communicated via intake passages 54 and 57. Similarly, the other intake chambers 44 of the intake manifold body 41 have the same intake valve opening timings which do not overlap each other.
The combustion chambers of the two cylinders (the second cylinder 51 and the third cylinder 52) communicate with each other through intake passages 55 and 56. In addition, each intake passage 54-57
An injection nozzle 58 for injecting fuel toward the passage is provided at a position downstream of the nozzle.

Inside the divided body 41b of the intake manifold body 41, an opening / closing control including a plurality of openings 59 provided in the partition wall 42 for communicating the two intake chambers 43 and 44 with each other and a butterfly valve for selectively opening / closing the openings. A valve 60 is provided. The opening / closing control valve 60 is driven by an actuator 61. The actuator is connected to a control unit connected to a rotation speed sensor 63 for detecting the rotation speed of the internal combustion engine.
Controlled by 62. The control unit 62 also controls the valve switching mechanism 14 via the hydraulic controller 64.

As described above, the first to fourth cylinders 50 to 53 of the internal combustion engine
Of the combustion chambers of which the intake valve opening timings do not overlap each other
The two cylinders of the cylinder 50 and the fourth cylinder 53 are an intake valve and an intake passage 54,
The second cylinder 51 and the third cylinder 52 communicate with the intake chamber 43 through 57.
Communicates with the intake chamber 44 via intake valves and intake passages 55 and 56, and these intake chambers are connected to an air cleaner (not shown) via throttle valves 46 and 47. The two intake chambers 43 and 44 can be selectively communicated with each other by an opening 59 in which an open / close control valve 60 is interposed (FIG. 5).

Next, the operation of the intake device according to the present invention will be described with reference to FIGS. 1 and 4 to 6. FIG.

The low-speed rotation range of the internal combustion engine, that is, the rotation speed N1 shown in FIG.
In a lower rotation range, the valve mechanism is set to the low speed mode, and the opening / closing control valve 60 is opened. Here, each of the intake valves 1a and 1b of the four cylinders is composed of a first cylinder 50-third cylinder 52-fourth cylinder 53.
Opening and closing in the order of the second cylinders 51..., For example, when the intake valves of the first cylinders 50 are closed, since the intake valves of the third cylinders 52 are already open, this occurs when the intake valves of the first cylinders 50 are closed. The pressure wave that flows reaches the intake chamber 44 via the intake passage 54 and the intake chamber 43, and then pays attention to the third cylinder 52.
It reciprocates with the inside through 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 forming one cycle of two reciprocations) and the timing of closing the intake valve of the cylinder are synchronized, the third cylinder 52 is closed. The filling efficiency can be increased. This is the same for each of the cylinders 50 to 53. Therefore, the filling efficiency in each of the cylinders 50 to 53 can be increased at a specific rotation speed of the internal combustion engine synchronized with the pulsation frequency. As a result, an inertia torque curve as shown by a curve I in FIG. 6 appears, and the lower torque peak is used.

When the rotation speed of the internal combustion engine increases and reaches N1, the output torque tends to slightly decrease. At this time, by closing the open / close control valve 60, the intake chamber 43 and the intake chamber 44 are isolated from each other. Here, when the intake chambers 43 and 44 are independent, since the intake valve opening timing of each cylinder in the same intake chamber does not overlap, for example, the pressure wave generated when the intake valve of the first cylinder 50 is closed is Then, the air reaches the intake chamber 43 via the intake passage 54, and then pays attention to the fourth cylinder 53, and reciprocates between the intake chamber 43 and the intake valve of the fourth cylinder 53 via the intake passage 57. When the timing (positive multiple of the pulsation frequency which forms one cycle of two reciprocations) reaching the intake valve as a positive pressure wave and the timing at which the intake and exhaust valves of the fourth cylinder 53 overlap are synchronized, the fourth cylinder
The residual combustion gas in 53 is wiped out, and the charging efficiency can be increased. Conversely, the charging efficiency of the first cylinder can be similarly increased. On the other hand, each cylinder on the intake chamber 44 side
The filling efficiency can be similarly increased for 51 and 52. At this time, when the opening timings of the intake valves of the cylinders in the same intake chamber do not overlap, the equivalent pipe length involved in the pulsation becomes shorter by the volume integral of the combustion chamber as compared with the case where the intake valves open. Accordingly, a resonance torque curve as shown by a curve II different from the curve I in FIG. 6 appears, and when the rotation speed is between N1 and N2 (N1 <N2), the torque peak is utilized.

When the rotation speed reaches N2, the open / close control valve 60 is opened again. When the rotation speed is between N2 and N3, (N2 <N
3) Again, the torque peak in the higher speed range of the inertial torque curve represented by curve I is utilized.

Next, when the rotation speed N3 is reached, the valve switching mechanism 44 described above is used.
To high-speed mode. Then, since the intake valve opening / closing timing in each of the cylinders 50 to 53 changes, the timing synchronized with the pulsation also changes, and both the inertia torque curve represented by the curve I and the resonance torque curve represented by the curve II become high. Shift to the rotation range side. At this time, for example, in the case of a conventional internal combustion engine employing only inertial intake for an internal combustion engine having a valve switching mechanism, a torque curve as shown by broken lines A and B is drawn in FIG. In such a torque curve, the output torque at the intersection of the broken lines A and B (rotational speed N3), that is, in the vicinity of the switching point of the valve mechanism tends to decrease, but in the inertial torque curves shown by the curves I and III, Rotation speed N3
Since both curves are relatively close to the torque peak, the output torque does not drop in the speed range. When the rotation speed is between N3 and N4 (N3 <N4), the torque peak of the inertia torque curve represented by the curve III in which the torque curve represented by the curve I is shifted toward the high-speed region is used. .

Then, when the rotation speed reaches N4,
60 is closed, and the torque peak in the higher speed range of the torque curve represented by curve IV in which the torque curve represented by curve II is shifted to the high-speed range side is used.

FIG. 7 is a schematic configuration diagram showing a second embodiment according to the present invention. The configuration of the present embodiment is substantially the same as that of the first embodiment. However, in the present embodiment, the intake passage is not provided by bending the intake passage as in the first embodiment, but reaches the first cylinder 70. The intake passage 74 and the intake passage 77 leading to the fourth cylinder 73 are gathered to form an intake chamber 78, and the intake passage 75 leading to the second cylinder 71 and the intake passage 76 leading to the third cylinder 72 are gathered for intake. Room 79. In addition, an opening 80 and an opening / closing control valve 81 are provided in a wall section separating the two intake chambers 78 and 79 from each other. Further, on the upstream side, throttle valves 82 and 83 interlocking with each other are provided as in the first embodiment.

It is needless to say that the present invention is not limited to the above-described embodiment, and various applications are possible. For example, the opening and closing of the opening and closing control valve in the present embodiment may be performed gradually to reduce a shock. Also, when the idling or rotation speed of the internal combustion engine changes suddenly as required, or when the load is reduced. When it is small, the opening and closing of the opening and closing control valve may be prohibited in order to improve the durability of the mechanical movable part. Further, in this embodiment, the opening / closing control valve is a butterfly valve. However, the opening / closing control valve may have an appropriate shape so as not to cause a passage resistance of the intake passage.

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

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a part of an internal combustion engine showing a first embodiment of an intake device according to the present invention. FIG. 2 is a configuration diagram schematically showing a part of the valve operating mechanism. FIG. 3 is a sectional view showing a main part of the valve train. FIG. 4 is a view taken along line IV-IV in FIG. FIG. 5 is a schematic configuration diagram of the intake device in the first embodiment. FIG. 6 is a graph showing the change in the output torque of the internal combustion engine together with the switching timing of the valve operating mechanism and the intake device according to the change in the rotation speed of the internal combustion engine. FIG. 7 is a view 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 cam 5-7 rocker arm 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 retainers 16a, 16b ... Valve springs 17, 20, 21 ... Guide Holes 25, 26: Piston, 27: Stopper 28: Compression coil spring, 30: Oil supply passage 32: Passage, 33: Port 41: Intake manifold body 41a, 41b, 41c: Split body 42 ... Partition walls, 42a ... Extensions 43, 44 ... Intake chambers, 43a, 44a ... Passages 45 ... Throttle bodies 46, 47 ... Throttle valves 50-53 ... First to fourth cylinders 54 to 57 ... … Intake passage, 58… injection nozzle 59… opening, 60… opening and closing control valve 61… actuator, 62… control unit 63… speed , 64 ... Hydraulic controllers 70-73 ... First to fourth cylinders 74-77 ... Intake passage, 78, 79 ... Intake chamber 80 ... Opening, 81 ... Opening / closing control valves 82, 83 ... Throttle valve

Claims (1)

(57) [Claims] A valve mechanism for switching an operation state between a low-speed mode and a high-speed mode in order to change an output torque of the engine according to an operating condition; an intake valve that is opened and closed by the valve mechanism; In order to connect between the intake valve port and the plurality of intake chambers, the intake passages provided separately for each cylinder whose opening timing of the intake valve does not overlap each other, and the communication / non-communication between the plurality of intake chambers are established. An on-off valve for selecting an on-off valve, wherein the on-off valve uses an output torque due to inertial supercharging in an open state, and an output device due to resonance supercharging in a closed state. Wherein each of the intake chambers has an inertial torque characteristic that fills a region where the resonance torque in each of the modes is low when they communicate with each other, and the valve train mechanism has an inertial torque in each of the modes. same Is switched between a low-speed mode and a high-speed mode at a rotational speed that substantially coincides with each other.The on-off valve opens and closes at a rotational speed at which inertia torque and resonance torque in each of the modes substantially coincide with each other, and An intake device for an internal combustion engine, wherein an open state is maintained at a switching rotational speed of each mode.