JPS60166707A - Suction device of engine - Google Patents

Abstract

PURPOSE:To enhance the output power by controlling a timing change means, which shall change at least the closing timing of suction valve, in linkage with an adjusting means for the suction gas inertia by means of change in the section area of the suction passage. CONSTITUTION:Each of the cylinders is furnished with two suction valves 14 and two exhaust valves 16, and the timing of one of the suction valves 14 shall be changeable by a timing change means 40. This timing change means 40 shifts the relative phase between a tappet 42 and can 36 by rotating a rotary member 41 round a cam shaft 35 through a control lever 45 and control rod 44 using an actuator 46, and thereby alters the opening/closing timing of the suction valve 14. A control circuit 30 controls the actuator 46 according to the operating condition of engine in linkage with an actuator 28 of a suction gas inertia adjusting means 20 which is to change the suction area of the suction passage 25 in accordance with the number of revolutions of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for an engine, and more particularly to a system that utilizes the intake inertia effect to improve output.

(Prior art) Conventionally, as seen in Japanese Patent Application Laid-Open No. 48-58214, pressure fluctuations in the intake passage are utilized by changing the cross-sectional area or length of the intake passage according to the engine speed. 2. Description of the Related Art Devices are known that increase suction efficiency in various engine speed ranges and improve output. In other words, pressure oscillations occur in the intake passage due to intermittent intake air as the engine operates, so if positive pressure waves of these pressure waves are introduced into the cylinder at the appropriate timing, the intake efficiency can be improved. can be increased. The timing at which positive pressure waves are introduced into the cylinder can be adjusted by changing the cross-sectional area or length of the intake passage, so by changing the cross-sectional area or length of the intake passage according to changes in engine operating conditions, In various operating ranges, the so-called dynamic effect of intake due to the above phenomenon, that is, the inertia effect and the pulsation effect, can be utilized for rightward movement to increase the intake efficiency.

By the way, in conventional devices of this type, the opening and closing timing of the intake valve is fixed, and the intake valve is closed when a predetermined crank angle is delayed from BDC (piston bottom dead center). Under these conditions, even if tuning is carried out to maximize the dynamic effect of positive pressure waves by adjusting the length or cross-sectional area of the intake passage, the internal cylinder changes due to engine operating conditions, such as changes in engine speed. As the pressure characteristics change, at low speeds the cylinder pressure increases before the intake valve is closed, causing blowback, and at high speeds, the cylinder pressure is low and J3 intake air can be introduced. In this situation, the intake valve will be closed.

On the other hand, as a means for improving intake efficiency when the length J3 and cross-sectional area of the intake passage are fixed, there is a method of adjusting the opening timing of the intake valve, particularly the valve closing timing, depending on the operating state of the engine. In this method, the opening and closing timing of the intake valve may be controlled according to the operating state of the engine so that the intake valve is closed when the cylinder pressure and the intake passage pressure immediately before the intake valve become equal. However, in this case, due to the length and cross-sectional area of the intake passage,
The synchronized state in which the positive pressure waves generated in the intake passage are utilized most effectively is limited to a specific operating range, and in other ranges the dynamic effect of the positive pressure waves is reduced. Therefore, there is a limit to the improvement in intake efficiency even by adjusting the opening/closing timing of the intake valve. Furthermore, it is mechanically difficult to adjust the opening/closing timing of the intake valve over a wide range.

(Objective of the Invention) In view of the above circumstances, the present invention aims to enhance the intake inertia effect in various engine operating ranges, and to make maximum use of this intake inertia effect to significantly increase intake efficiency and improve output performance. The purpose of the present invention is to provide an engine intake device that can perform the following functions.

(Structure of the Invention) The present invention provides an intake inertia adjusting means that adjusts the intake inertia by changing the cross-sectional area or length of the intake passage depending on the operating state of the engine, and at least variable closing timing of the intake valve. and timing adjustment means for adjusting the valve closing timing in conjunction with the intake inertia adjustment means according to the operating state of the engine. In other words, the intake inertia adjustment means adjusts the cross-sectional area of the intake passage or [
, L length is adjusted, and in conjunction with this, the intake timing is corrected by the timing adjustment means, thereby making it possible to maximize the intake inertia effect and increase the intake efficiency.

Note that the cross-sectional area and length of the intake passage in this configuration refer to the cross-sectional area and length of the flow passage that substantially contributes to the intake inertia effect.

(Embodiment) FIG. 143 and FIG. 2 show a first embodiment of the present invention. In these figures, 1 is an engine body equipped with a plurality of cylinders 2, and is composed of a cylinder block 3, a cylinder head 4, a cylinder head cover 5, etc. A piston 6 is inserted into each cylinder 2, and the piston 6 is inserted into each cylinder 2. 6
A combustion chamber 7 is formed above. Each combustion chamber 7 is equipped with a spark plug 8, and two intake boats 9°1 each formed in the cylinder head 4.
0 exhaust boats 11.12 are open, and these boats 9-12 are opened and closed by first and second intake valves 13.14 and first and second exhaust valves 15.16. It has become. The above both intake bows 1 to 9.10 are:
The cylinder head 4 is connected to the cylinder head 4 near its side ends Bi and J, and communicates with each other, and this communication portion 17 is equipped with a fuel valve 10 and a fuel valve 18.

The intake system for the engine body 1 is provided with an intake inertia adjusting means 2o as described below, which adjusts the cross-sectional area of the intake passage in accordance with the engine speed. In other words, the intake system includes an air cleaner (not shown) and slot valves 1 to 2.
3, and a branch pipe 22 branched from this surge tank 21 for each cylinder and connected to the communication part 17 of both the intake boats 9 and 10. intake boat 9,1o
A movable wall 24 is provided inside a portion extending to the vicinity of the combustion chamber side opening. This movable wall 24 has one end attached to one side of the upstream end of the branch pipe 22 via a rotatable small wall 24a, and connects the branch pipe 22 and the intake boats 9, 1o to the surge tank. A substantial intake passage 25 that communicates with 21 and a non-passage portion 2 that does not communicate with surge tongue 21.
It is divided into 6 parts. This is possible! ! The middle part of the I-wall 24 is connected via a rod 27 to an actuator 28 which is controlled by a control circuit 30;
This control circuit 30 receives a detection signal from an engine rotation speed sensor 131. By swinging the movable wall 24 in accordance with the engine speed, the substantial cross-sectional area of the intake passage 25 is adjusted to synchronize the intake inertia as will be described in detail later. .

Further, as a valve operating mechanism for the intake and exhaust valves 13 to 16, camshafts 3 for intake valves and exhaust valves are mounted on the cylinder head 4 and are rotationally driven by a crankshaft (not shown).
5.37 are arranged, and each cam shaft 35.37 has a cam 36.
．． 38 are arranged. The exhaust valves 15 and 16 are opened and closed at a constant timing by the cam 38 via the tappet 39, and the first intake valve 13 is similarly opened and closed at a constant timing, but the second intake valve 14 is opened and closed at a constant timing. The timing of the operation is adjusted by the timing adjusting means 40 as shown in FIG. That is, the second intake valve 14 is equipped with a rotating member 41 that is rotatable about the camshaft 35, and a tappet member 42 is held at the lower part of the rotating member 41. This tappet member 42 has a flat upper surface 428 that contacts the cam 3G provided on the cam @35.
The lower surface 42b is formed into an arcuate or spherical shape centered on the camshaft, and the upper end of the valve stem 14a of the second intake valve 14 is in contact with the lower surface 42b. Further, a control rod 44 parallel to the camshaft 35 passes through the upper end protrusion 43 of the rotating member 41, and a control lever 45 is engaged with the control rod 44. The control lever 45 is slidable in a direction perpendicular to the axial direction of the control rod 44 and is actuated by an actuator 46 attached to the side wall of the cylinder head cover 5.
This actuator 46 is controlled by the control circuit 30.

According to such means, when the rotary member 41 is rotated by the actuator 4 [5] via the control lever 45 and the control rod 44, the relative phase between the tappet member 42 and the cam 36 is accordingly changed. As a result, the opening/closing timing of the second intake valve 14 is changed. In other words, when the rotating portion tA41 is rotated in the same direction as the rotational direction X of the camshaft 350, the above-mentioned opening/closing timing is delayed, and when it is rotated in the opposite direction, the above-mentioned Ii%1f31] timing is advanced. .

In the case of this timing adjustment means 40, as shown in FIG. By making it possible to change the opening/closing timing from the same timing as 13 to the direction in which the opening/closing timing is changed, the opening timing of the intake valve determined by the second intake valve 14 is maintained constant while the opening timing of the intake valve by the first intake valve 13 is kept constant. There is a roar as the valve closing timing is adjusted.

Next, the action of this intake device is shown in Fig. 4, J5, J, and 5.
This will be explained using the characteristic diagram shown in the figure.

Figure 4 shows, with the horizontal axis as the crank angle, the fluctuation characteristics of the cylinder pressure at a specific engine speed of 1J3G, various pressure waves in the intake inertia tuning state at a constant fi-J'', and the resultant pressure of these. The figure shows the fluctuation characteristics of the pressure immediately before a certain intake valve.As shown by curve A in this figure, the cylinder pressure gradually decreases from time TI)C, which is 10 years after the intake valve opens, and reaches negative pressure on the way down of the piston. After reaching the peak, the pressure gradually increases and becomes positive pressure after passing the BDC point.On the other hand,
The downward movement of the piston during the intake stroke generates a negative pressure wave shown by curve B in this figure just before the intake valve. The first reflected wave becomes a positive pressure wave as shown by curve C and returns to the cylinder side. Further, the second reflected wave returns as a negative pressure wave as shown by the curved line. The pressure just before the intake valve (curve E) is a combination of the four pressure J waves shown by these curves B, C, and D. The intake inertia tuning state due to the intake passage itself means that the waveform of the first reflected wave just before the intake valve is at the midpoint between TOC and BOC, as shown in this figure.
This is a state in which the intake inertia effect of the intake passage itself is maximized by this first reflected wave, which starts to appear from a short distance and reaches a peak at a specific point past BDC. In other words, the pressure immediately before the intake valve is maximized at the appropriate time after BDC,
This refers to a state in which the characteristics are optimal for the intake inertia effect. In this state, the pressure immediately before the intake valve shown by curve E becomes sufficiently large as the cylinder pressure until the combustion chamber volume is large B D Cd3 and thereafter. This allows a large amount of intake air to flow into the engine, increasing the intake inertia effect. If the timing at which the first reflected wave returns is delayed from the above-mentioned synchronized state, the pressure rise at the intake valve direct 1) a will be delayed and B
As the pressure difference in the cylinder pressure near DC becomes smaller, the suction efficiency tends to decrease, and when the above timing is earlier than the synchronized state, the peak value of the pressure just before the intake valve decreases due to the influence of the second reflected wave. Therefore, the suction efficiency tends to decrease. Note that IC indicates the Iυ appropriate opening/closing timing of the intake valve, which is after BDC. It shows a fluctuation characteristic d3 and a fluctuation characteristic of the pressure just before the intake valve. In this figure, the curve Δ1. A2 and Δ3 indicate the fluctuation characteristics of the cylinder pressure at low engine speed 114, medium speed J3, and high engine speed, respectively, and as the engine speed increases, the crankshaft rotation period becomes λ(l Due to compression, the rise in cylinder pressure tends to lag.Also, in this figure,
As mentioned above, the fluctuation characteristic of the pressure immediately before the intake valve when the intake inertia is in a synchronized state is shown by a solid line curve E, and the intake inertia is synchronized when the engine rotates at medium speed. Curves Fρ and E represent the fluctuation characteristics of the direct pressure of the intake valve at low speed rotation and high speed rotation, respectively, using two-dot chain lines, assuming that the height and length are fixed.
It is indicated by h. If the cross-sectional area and length of the intake passage are fixed in this way, the timing at which the first reflected wave returns to the cylinder side changes mainly depending on changes in engine speed, so the power just before the intake valve increases at high speeds. is delayed, and the pressure immediately before the intake valve is attenuated early at low speed rotation.

Therefore, in the intake inertia adjusting means 20, the cross-sectional area of the intake passage is adjusted so that the intake inertia tuning state is maintained even if the engine speed changes.

In other words, the timing at which the first reflected wave returns to the cylinder side is advanced as the cross-sectional area of the intake passage is increased, so as the engine speed decreases, the actual cross-sectional area of the intake passage 25 is reduced and the engine As the rotational speed increases, the movable wall 24 is actuated by the control circuit 30 via the actuator 28 so as to increase the cross-sectional area. As a result, even if the engine speed fluctuates, fluctuations in the intake inertia effect accompanying this are suppressed, and the pressure immediately before the intake valve is maintained at a characteristic that approximates curve E in Figure 5. The effect is enhanced.

In this figure, IC2 indicates the optimal intake valve closing timing at medium speed rotation, and this timing is the timing when the cylinder pressure at medium speed rotation and the pressure just before the intake valve match (curve E and curve A2 This corresponds to the period when the two intersect with each other, and if this is done, the suction efficiency at medium speed rotation will be maximized. However, if the timing is fixed to lC2, even if the intake inertia is synchronized by the intake inertia adjustment means 20, the characteristics of the cylinder pressure will change depending on the engine speed as described above, so at high speed rotation, the curve E The intake valve is closed at a time when it is still possible to inhale from the pressure level before the time when curve E and curve Δ3 intersect, and at low speed rotation, the cylinder internal pressure is higher than the time when curve E and curve A1 intersect. situation,
Therefore, the intake valve is closed only after the intake system is in a state where blowback occurs.

Therefore, the timing adjustment means 40 corrects the intake timing in accordance with the engine rotation speed in association with the adjustment of the pressure just before the intake valve by the intake inertia adjustment means so as to obtain the maximum intake efficiency. That is, by rotating the rotating member 41 by the actuator 46 that receives a signal from the control circuit 30, the pressure immediately before the intake valve, which is adjusted to the intake inertia synchronization state, always matches the cylinder internal pressure. The second intake valve 14 is closed at the point when the second intake valve 14 is closed, and therefore, during high speed rotation, the valve opening timing is delayed at point IC3 at u and y where curve E and curve A3 intersect; The valve closing timing is advanced until the time point Ic1 when the values intersect. In this way, the suction efficiency can be maximized through the synergistic action of the intake inertia adjustment means 20 and the timing adjustment means 40.

In addition, with the cross-sectional area and length of the intake passage fixed, only the intake valve closing timing is determined at the intersection point IC3' of the curve Eh and the curve A3 at high speed rotation, and at the intersection point IC1 of the curve EQ and curve Δ1 at low speed rotation 111λ. 'By adjusting the intake inertia and adjusting the valve closing timing in relation to this, BDC
Since the pressure difference between the pressure just before the intake valve and the pressure inside the cylinder increases, the suction efficiency is greatly increased. Furthermore, when adjusting only the intake valve closing timing, the valve closing timing can be changed to
Although it is necessary to adjust the valve over a relatively wide range as shown by line F in the figure, it is extremely difficult to adjust the valve closing timing over a wide range.

On the other hand, if you adjust the valve closing timing after synchronizing the intake 1 ('1) characteristic, you can reduce the amount of valve closing timing adjustment as shown by line G, and it is mechanically advantageous. be.

13. Such an improvement in suction efficiency is required in the 1mm load range, so it is necessary to increase the engine speed only when the engine load is 111' + JJ and 100mm. It is also possible to perform control such that the intake inertia is not synchronized in order to reduce pumping loss or the like during low load by tuning the intake IC characteristics and adjusting the intake valve closing timing accordingly. In this case, in addition to the detection signal from the engine rotation speed sensor 31, the control circuit 30 receives the first
It is sufficient to input the detection signal from the load sensor 32 (not shown by the two-dot chain line in the figure) to the J5G.

FIG. 7 J3 and FIG. 8 show a second embodiment of the present invention, and in this embodiment, the intake inertia adjusting means 50 is configured to switchably adjust the intake passage cross-sectional area in two stages. . In other words, a first intake passage 54 and a second intake passage 55 are defined by a partition wall 53 in a branch pipe 52 branched from the bark tank 51 for each cylinder. is the communication part 17 of both intake bows 1-9.10.
17iJ is connected to the 12 intake passages 55.
A closing valve 56 is provided. During this period, the fR] valve 56 is activated by an actuator 57 that receives a signal from the control circuit 30.
It is opened and closed by the information 58, and is closed when the engine speed is less than a set value, and is closed when the engine speed is higher than the set value. By doing this, the on-off valve 5
6 is closed, intake air is supplied to both the intake boats 9 and 10 only from the first intake passage 54, and the cross-sectional area of the first intake passage 54 becomes the substantial intake passage cross-sectional area, and the opening/closing valve 56 is open, both intake passages 54
, 55, and both intake passages 54.5
The sum of the cross-sectional areas of 5 becomes the substantial cross-sectional area of the intake passage. When the opening/closing valve 56 is closed to reduce the intake passage cross-sectional area, the intake inertia is synchronized in a specific engine speed range lower than the set rotational speed, and the opening/closing valve 56 is opened to reduce the intake passage cross-sectional area. In the increased state, the intake inertia is synchronized in a specific engine rotation speed range higher than the set rotation speed, and thus the intake inertia adjustment means 50 is configured. The structure of the timing adjustment means 40 for the intake valve and other parts are the same as in the first embodiment.

According to this embodiment, when the engine speed is less than the set speed, air is taken only from the first intake passage 54, so that the intake inertia is synchronized in a relatively low 1 engine speed range, and the set speed is lower than the set speed. When the engine speed exceeds the engine speed, the on-off valve 56 is opened and the substantial cross-sectional area of the intake passage increases, so that the intake inertia is synchronized in a relatively high engine speed range. Even in other engine speed ranges, compared to the case where the cross-sectional area of the intake passage does not change, the intake inertia is brought closer to the synchronized state, and the intake inertia effect of the intake passage itself is enhanced over a wide engine speed range.

Furthermore, in this case as well, since the intake timing is corrected by the timing adjusting means 40 in conjunction with the adjustment of the intake inertia, the intake efficiency is further improved.

FIG. 9 shows a third embodiment of the present invention, in which:
The intake inertia adjusting means 60 is configured to switchably adjust the length of the intake passage in two stages.

In other words, a cylindrical surge tank 6 is installed inside a casing 63 in which linear cylinder-specific branch pipes 62 are integrally connected.
1 is fixed, an annular intake passage extension 64 that communicates with the branch pipe 62 is formed in the casing 63 along the outer periphery of the surge tank 61. The intake passage extensions 64 are divided into cylinders corresponding to each branch pipe 62 by partition walls (not shown) provided at regular intervals in the length direction of the casing 63. The above-mentioned tank 61 includes a branch pipe 62 and an intake passage extension 6.
4. An opening 65 is provided at which communication point, and between this opening 65 and the upstream end of the branch pipe 62,
A switching valve 6G is provided which is operated by an actuator (not shown) in response to a signal from the control circuit 30. When the engine speed is less than the set speed, the switching valve 66 connects the opening 65 and the branch pipe 6 as shown by the solid line J.
2, the branch pipe 62 is operated from the surge tank 61 through the intake passage extension 64.
When the rotation speed is higher than the set rotation speed, the switching valve 66 directly connects the opening 65 and the branch pipe 62 as shown by the two-dot chain line.
4, and connect the branch pipe 62 from the surge tank 6'1.
J, where the intake air is sent directly to the sea urchin. In this way, the actual length of the intake passage can be changed in a switchable manner. The structure of the timing adjustment means 40 etc. for the intake valve is as described in the first section. This is almost the same as the second embodiment.

By changing the length of the intake passage, the intake inertia effect can be adjusted, and the same effect as in the second embodiment is achieved in this embodiment.

FIG. 10 shows a fourth embodiment of the present invention, and in this embodiment, an intake inertia adjusting means 70 is configured to adjust the length of the intake passage steplessly. That is, a cylindrical 1-nerge tank 71 is rotatably held inside a casing 73 in which linear cylinder-specific branch pipes 72 are integrally connected, and a surge tank 71 inside the casing 73 is rotatably held.
A spiral intake passage extension 74 whose downstream end communicates with the branch pipe 72 is defined around each cylinder. The upstream end of this intake passage extension 74 is sealed by a seal wall 75 in contact with the outer periphery of the surge tank 71. The surge tank 71 is provided with an opening 76 that opens into the intake passage extension 74. () It's rare.

The surge tank 71 is rotated in response to fluctuations in engine speed by an actuator (not shown) that receives a signal from the control circuit 30. In this way, the substantial length of the intake passage from the rear position of the surge tank 71 to the side part of the combustion chamber of the intake boat can be changed steplessly. The structure of the timing adjustment means 40 and the like is the same as in the first to third embodiments.

In this embodiment, when the engine speed is low, the surge tank 710 is opened.
4, the intake passage is lengthened, and as the engine speed increases, the surge tank 71 is rotated so that the opening 76 approaches the downstream side of the intake passage extension 74. The same effect as in the first embodiment is achieved.

J3, the valve closing timing adjusting means in the intake valve timing adjusting means is also limited to the structure shown in the figure, and its axial position can be adjusted using, for example, a three-dimensional cam.
Alternatively, a valve adjustment member operated by hydraulic pressure or the like is interposed in the bush rod type valve mechanism, or a phase difference adjustment means is incorporated into the belt transmission mechanism between the crankshaft and the camshaft.
J construction can also be adopted. Further, in the above embodiment, 2
In a structure in which the intake valves 1-9.10 are shifted to the right, the intake valve closing timing is shifted by 1, but using a three-dimensional cam etc. The timing and valve lift amount may be adjustable, or the valve closing timing etc. may be adjusted in this manner in a structure in which one intake boat opens into the combustion chamber.

(5R, light effect) As described above, the present invention brings the intake inertia into a synchronized state according to the operating condition of the engine, and bt, < is close to this (= J ruru J: The valve closing timing of the intake valve is adjusted in order to make maximum use of the intake inertia effect. It is possible to significantly increase suction efficiency and improve output.Moreover, compared to a method that only adjusts the valve closing timing, the amount of variation in the optimal value of the valve closing timing in response to fluctuations in engine operating conditions can be reduced. It is possible to make the adjustment small and to effectively improve output over a wide range of engine operating ranges.

[Brief explanation of the drawing]

Fig. 1 shows a first embodiment of the device of the present invention; Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1; and Fig. 3 shows the opening/closing timing of the intake and exhaust valves. Fig. 4 is a characteristic diagram of the cylinder internal pressure and various pressure waves just before the intake valve, and Fig. 5 is a characteristic diagram of the cylinder internal pressure and the intake valve pressure in several regions in various engine dishes. , FIG. 6 is an explanatory diagram showing the relationship between engine speed and intake valve closing timing,
FIG. 7 shows a second embodiment of the device of the present invention; a vertical sectional view;
FIG. 8 is a bottom view taken along the line ■-■ in FIG. 7, FIG. 9 is a vertical sectional view showing a third embodiment of the device of the present invention, and FIG. 10 is a fourth embodiment of the device of the present invention. FIG. 11 is an explanatory diagram showing another example of the opening/closing timing of the intake valve. 1...Engine body, 9.10...Intake port, 1
3.14... Intake valve, 20.50, 60.70...
Intake inertia adjustment means, 40...timing adjustment means. Particular ii') Applicant: Toyo Kogyo Co., Ltd. Figure 2 Figure 3: j> Figure 4

Claims (1)

[Claims] 1. Intake inertia adjusting means for adjusting the intake inertia by changing the cross-sectional area or length of the intake passage in accordance with the operating condition of the engine; and at least the closing timing of the intake valve is variable in accordance with the operating condition of the engine. An intake system for an engine, comprising: timing adjustment means for adjusting the valve closing timing in association with the intake inertia adjustment means.