JPH048250Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an engine intake system including a cylindrical rotary valve that controls the opening/closing period of an intake passage.

(Prior art) Engine output is generally controlled by opening and closing a throttle valve installed in the intake passage to adjust the amount of intake air. Due to the reduction in the opening degree of the throttle valve, so-called throttling loss or pumping loss increases, resulting in a problem of deterioration of fuel efficiency and the like. To deal with this problem, for example, according to Japanese Patent Application Laid-Open No. 58-23245, a shutter valve that opens when the accelerator opening exceeds a predetermined opening is installed in a large diameter main intake passage (secondary opening). A small-diameter bypass passage (primary side intake passage) that bypasses the shutter valve.
A configuration is shown in which a rotary valve that is opened and closed by rotation of a crankshaft or a camshaft is disposed at a predetermined portion of the passage. this is,
It is called an NA Miller cycle engine, and when the engine is under low load (when the accelerator opening is below a predetermined opening), the shutter valve is closed and intake air can be supplied only from the bypass passage. In this state, the rotary valve is closed during the intake stroke, and the intake air amount is adjusted by changing the closing timing according to the load and the like. According to this type of engine, when the timing valve is opened, the degree to which the intake air passing through the bypass passage is throttled by the valve is extremely small, and the substantial period of the intake stroke is shortened. This effectively reduces throttling loss or pumping loss during low loads, making it possible to improve fuel efficiency and the like.

However, in an engine equipped with a rotary valve as described above, the following problem occurs at low rotation speed and low load, especially at idle.

That is, as shown in FIG. 9, when the engine is idling, the opening of the rotary valve A
Since the period during which the intake passage (bypass passage) B is opened via A', that is, the opening period of the valve A, hardly overlaps with the opening period of the intake valve C (at this time, the main intake passage D is completely closed), the flow rate of intake air passing through the opening A' of the rotary valve A during the intake stroke is extremely small or zero. However, even in such a case, during the opening period of the intake valve C, which is not during the intake stroke,
Intake air passes through the opening A' of the valve A and flows into the downstream side of the intake passage B, and this inflowing intake air is supplied into the combustion chamber E during the intake stroke when the valve A is in a closed state. Therefore, it is possible to secure intake air during idling. However, the opening of the rotary valve A
A' has a large opening area in order to ensure a sufficient amount of intake air in high-speed, high-load areas, etc., but due to the layout, the rotary valve A and combustion chamber E are placed close together. Due to the fact that the downstream side of the valve A in the intake passage B is lengthened and a large dead volume is present, a large amount of intake air flows through the opening of the rotary valve A during idling as described above.
It passes through A' and flows into the downstream side of the intake passage B. Therefore, during the intake stroke when the rotary valve A is in the closed state, the amount of intake air supplied into the combustion chamber E from the downstream side of the intake passage B does not correspond to the amount at idle, that is, the intake air filling amount is the desired amount. As a result, it becomes difficult to lower the engine speed to the desired idle speed, and fuel efficiency deteriorates.

(Purpose of the invention) The present invention is intended to solve the above-mentioned problem regarding an engine intake system that is equipped with a cylindrical rotary valve in the middle of an intake passage to control the timing of opening and closing of the passage. By changing the opening area of the rotary valve according to the engine speed using the configuration or configuration, the rotary valve can be used at low rotational speeds and low loads of the engine (for example, when the rotary valve is installed in a so-called NA Miller cycle engine). This makes it possible to reduce the intake air charge as desired, especially at idle). This not only ensures output performance when the engine is running at high speeds and under high load, but also lowers the idle speed to the desired speed to ensure a good idle state, thereby preventing deterioration in fuel efficiency, etc. The purpose is to

(Structure of the invention) The present invention is characterized by the following structure in order to achieve the above object.

That is, it is equipped with a cylindrical rotary valve that is rotationally driven by a crankshaft or camshaft and has an opening through which intake air passes, and is configured to control the opening and closing timing of the intake passage by this rotary valve. In an engine intake system, a valve opening period control plate changes the valve opening period of the rotary valve by protruding and retracting from the opening of the rotary valve, and the control plate is biased in a direction to protrude into the opening. an elastic member made of a spring or the like, and the direction of movement of the control plate is in the circumferential direction of the rotary valve so that the valve opening period control plate is moved backward by the centrifugal force generated as the rotary valve rotates. tilt it against the

According to such a configuration, in a high-speed, high-load region of the engine, the centrifugal force generated in the rotary valve increases as the rotation of the rotary valve increases. The valve is retracted against the biasing force (spring force) of the member, and the area (substantive opening area) of the opening of the valve increases.

On the other hand, in the low rotation and low load range of the engine, especially in the idle range, the rotational speed of the rotary valve decreases significantly and the centrifugal force becomes small. The area of the opening is reduced by protruding into the opening.

(Effects of the invention) As described above, according to the invention, in an engine intake system equipped with a cylindrical rotary valve that controls the timing of opening and closing of the intake passage, when the rotary valve is operated at high speeds and under high load, etc. The opening area of the valve is increased to lengthen the opening period of the valve, and the opening area of the valve is made smaller to shorten the opening period during low rotation and low load conditions (particularly when idling). The engine speed during idle is suppressed while ensuring the required engine output, making it possible to maintain a good idle state.

In particular, according to the present invention, when the rotary valve is installed in a so-called NA Miller cycle engine, the actual valve opening period of the rotary valve (the overlap period between the rotary valve opening period and the intake valve opening period) is Since the area of the opening formed in the valve is relatively large and there is a large dead volume between the valve and the combustion chamber in the intake passage, such as when the engine is idling, which is zero or almost zero, The problem of not being able to reduce the intake air filling amount to the desired amount corresponding to the idle state is avoided, and deterioration of the idle state in this type of engine is effectively prevented or suppressed.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

In this embodiment, the present invention is applied to a 4-cylinder, 4-cycle engine.

As shown in FIGS. 1 and 2, the cylinder head 2 of the engine 1 has first to fourth cylinders 3 arranged in series.
Intake ports ₅ 1 - _{5 4} and exhaust ports 6 ₁ - 6 ₄ each having one end opened in the combustion chambers 4 ₁ - 4 ₄ in ₁ - 3 ₄
are formed, and intake valves 7...7 and exhaust valves 8...8 are respectively disposed at the openings of these two ports to the combustion chambers ₄₁ to ₄₄ , and above the central portion thereof are provided valves (not shown). The above-mentioned intake and exhaust 7...
A plurality of cams 9'... which open and close 7, 8...8.
A camshaft 9 having a diameter 9' is arranged in the cylinder row direction.

The engine 1 also includes a secondary intake passage 1 having a large passage cross-sectional area, the downstream end of which communicates with the combustion chambers 4 ₁ to 4 ₄ via the intake ports 5 ₁ to 5 ₄ , respectively.
0 ₁ to 10 ₄ are provided, and these passages 10
The upstream ends of cylinders ₁ to 10 ₄ are passages 10 ₁ and 10 2 corresponding to the first cylinder 3 ₁ and second cylinder 3 ₂ and passages 10 ₃ corresponding to the third cylinder 3 ₃ and fourth cylinder _{3 4} . ,10 ₄
are joined together and communicated with the inside of a carburetor 11 (fixed to the top of the bracket 11a) provided on the side of the engine body. Although not shown, the carburetor 11 is provided with a ventilate section that generates negative pressure when the intake air taken in from the air cleaner passes through, and a fuel nozzle whose tip is opened in the ventilate section. ing. Shutter valves _{12 1} to 12 ₄ that open and close the respective passages 10 ₁ to 10 ₄ are disposed at the downstream ends of the secondary intake passages 10 1 to 10 ₄ , respectively. ₁ ~12 ₄
are integrally connected so that they can be opened and closed by a rod 13 extending in the direction of the cylinder row, and are biased in the closing direction by the spring force of a spring 14 wound around one end of the rod 13.

Further, in this engine 1, the secondary intake passages 10 ₁ to 10 ₄ are arranged below, and the downstream ends thereof are opened in the vicinity of the combustion chambers 4 ₁ to 4 ₄ in each of the intake ports 5 ₁ to 5 ₄ . Primary side intake passages 15 1 to 15 _{4 are provided with relatively small passage cross-sectional areas, and whose upstream ends are opened to the upstream confluence of the secondary side intake passages 10 1 to 10 4 through the communication} passage 15a. There is. These primary side intake passages 15 ₁ to 15 ₄ are connected to each combustion chamber 4 ₁ to _{4 4 .}
In order to generate a so-called swirl in which the intake air swirls in the circumferential direction within the combustion chambers, the passage shape is such that the inflow direction of the intake air from the downstream end opening is offset with respect to the center of the combustion chambers 4 ₁ to 4 ₄ . On the way,
A cylindrical rotary valve 16 is provided which controls opening and closing of each of the passages 15 ₁ to 15 ₄ by being rotationally driven in synchronization with the rotation of the camshaft 9 (rotation in the direction a shown in FIG. 2).

The rotary valve 16 is a hollow cylindrical member extending in the direction of the cylinder row, and is rotatably held via a sleeve 18 fitted in the support portion 17, and is provided at the peripheral wall of each primary side intake. Each cylinder 3 ₁ is located at a position facing the passages 15 ₁ to 15 ₄ .
The first to _fourth openings 16 ₁ to 1 are opened at predetermined angular intervals (every 90 degrees) to correspond to the intake stroke timings of 1 to 3 4.
6 ₄ is formed. In that case, in this embodiment, the intake order is first cylinder 3 ₁ → third cylinder 3 ₃
→ 4th cylinder 3 ₄ → 2nd cylinder 3 ₂ , so
For example, when the intake stroke of the first cylinder ₃₁ is performed through the primary side intake passages ₁₅₁ to ₁₅₄ , the intake air or air-fuel mixture corresponds to the fourth cylinder ₃₄ , which is two strokes later than the cylinder ₃₁ . The internal space 16a of the rotary valve 16 is accessed from the upstream side of the primary intake passage ₁₅₄ through the fourth opening ₁₆₄ of the rotary valve 16.
After that, it flows into the combustion chamber 4 of the cylinder 3 1 through the first opening 16 ₁ in the valve 16 to the downstream side of the primary intake passage _{15 1 corresponding} to the first cylinder 3 ₁ . ₁ is now being supplied.

On the other hand, the rotary valves 16 disposed in the primary side intake passages 15 ₁ to 15 ₄ and the secondary side intake passage 1
Shutter valves 12 1 _{to 12} arranged at 0 ₁ to 10 ₄
The drive mechanism 20 for opening and closing 12 ₄ is constructed as shown below.

That is, the drive mechanism 20 includes a sun gear 21a fixed to the end of the rotary valve 16 on the fourth cylinder ₃₄ side, and three pinion gears 21b meshed with the sun gear 21a and arranged in an equilateral triangle shape.
21d, a ring gear 21e which is an internal gear meshed with the pinion gears 21b to 21d and whose outer periphery is a pulley; and the pinion gear 21
The planetary gear device 21 includes a carrier 21f that rotatably holds the gears b to 21d via support shafts 21b' to 21d'. A timing belt 22 is wound around the ring gear 21e (pulley) of the device 21 and the pulley 9a fixed to the end of the camshaft 9, and the rotation of the camshaft 9 is transmitted to the rotary valve via the belt 22. In this case, the diameters of the ring gear 21e and pulley 9a and the gear ratio of the planetary gear device 21 are adjusted so that the rotation transmission ratio of the camshaft 9 to the rotary valve 16 is "1". is set to a predetermined value. Further, the carrier 21f in the planetary gear device 21 has an upper portion connected to an accelerator pedal (not shown) via a wire 23, and when the accelerator pedal is depressed, the carrier 21
When f is rotated clockwise in the side view shown in FIG. 2, the sun gear 21a and ring gear 21 are rotated.
The relative position with respect to e is shifted.
As the carrier 21f rotates clockwise in FIG. 2 in this manner, the opening/closing timing of the rotary valve 16 is gradually delayed, thereby increasing the substantial opening period of the valve 16 as shown in FIG. 3. As T ₀ (the overlap period between the opening period T ₁ of the rotary valve 16 and the opening period T ₂ of the intake valve 7) gradually becomes longer, the amount of depression of the accelerator pedal, that is, the accelerator opening reaches the predetermined opening. The valve opening period T ₁ of the rotary valve 16 almost completely overlaps the valve opening period T ₂ of the intake valve 7 so that the above-mentioned substantial valve opening period T ₀ becomes maximum when It is composed of

Further, this drive mechanism 20 includes three pinions 21b to 2 that constitute the planetary gear device 21.
A link 24 is swingably held at one end by a support shaft 21c' of a pinion 21c disposed above the pinion 1d, and has an elongated hole 24a formed at the other end, and a link 24 that is loosely fitted into the elongated hole 24a of the link 24. The fitted pin 25a is fixed at one end and the other end is the shutter valve 1.
A lever 25 is fixed to a rod 13 connecting 2 ₁ to 12 ₄ , and when the accelerator pedal is depressed, the link 24 moves to the right in a side view of FIG. 2, and the lever 25 is rotated clockwise. By doing so, the shutter valves 12 ₁ to 21 ₄ are opened. In this case, the length of the elongated hole 24a formed in the link 24 is such that the actual valve opening period T ₀ of the rotary valve 16 substantially completely overlaps the valve opening period T ₂ of the intake valve 7 from the zero state. It _is set to correspond to the amount of depression of the accelerator pedal (accelerator opening degree) until the state is reached.
12 ₄ is the rotary valve 1 as shown in Figure 4.
The valve is opened when the actual valve opening period T ₀ (opening degree) of 6 reaches the maximum accelerator opening or a predetermined opening θ ₀ slightly lower than that opening, and the valve is opened at an even higher accelerator opening. The degree of opening is gradually increased as the distance increases.

The rotary valve 16, which is one of the main components of this engine 1 (NA Miller cycle engine), is constructed as shown below.

That is, as shown in FIGS. 5 and 6, the opening period of the valve 16 is variably controlled by changing the opening area of the first to fourth openings 16 ₁ to 16 ₄ of the rotary valve 16. Valve opening period control board 30 ₁ to 3
0 ₄ are arranged respectively. This valve opening period control plate 30 ₁ (the control plates 30 ₂ to 30 ₄ provided in the second to fourth openings 16 ₂ to 16 ₄ also have the same configuration, so the explanation will be omitted below) is connected to the rotary valve. Guide groove 1 formed in peripheral wall 16b of valve 16
6c and is capable of protruding and retracting with respect to the opening ₁₆₁ , one end is fixed to the protruding end surface of the control plate ₃₀₁ , and the other end is opposite to the protruding end surface. It is biased in the protruding direction by coil springs 31, 31 (other elastic members may be used) fixed to the inner end surface of the opening ₁₆₁ .
In this embodiment, the control plate 30 ₁ is curved at a predetermined curvature with respect to its moving direction, and the guide groove 16c is also curved in a similar manner.

As shown in FIG. 6, the guide groove 16c is inclined at a predetermined angle α toward the outer peripheral surface in the rotational direction b of the rotary valve 16 with respect to the inner peripheral surface or the outer peripheral surface of the rotary valve 16. The control plate ₃₀₁ is configured to move backward along the groove 16c against the spring force of the coil springs 31, 31 due to the centrifugal force generated as the valve 16 rotates. .

As described above, according to the configuration shown in the above embodiment, in the low load region where the shutter valves 12 ₁ to 12 ₄ disposed in each of the secondary side intake passages 10 ₁ to 10 ₄ are maintained in a fully closed state, , the flow rate of the mixture supplied from the carburetor 11 to each combustion chamber 4 ₁ to 4 ₄ is controlled by a rotary valve 16 disposed in the primary side intake passage 15 ₁ to 15 ₄ , and the supply of the mixture is controlled by the intake passage. By ending the process in the middle of the stroke, pumping loss is effectively reduced and combustibility, etc. is improved. Furthermore, as described above, when the air-fuel mixture is supplied from the primary side intake passages 15 ₁ to 15 ₄ , a swirl of the air-fuel mixture is generated in the combustion chambers 4 ₁ to 4 ₄ , so that a good performance in this low load region is achieved. This makes it possible to ensure good combustibility.

Particularly, according to the above embodiment, when the engine speed is at idle, which is less than the predetermined speed _N1 shown in FIG. 7, due to the low rotational speed of the rotary valve 16, The centrifugal force acting on the valve opening period control plates 30 ₁ to 30 ₄ disposed at the openings 16 ₁ to 16 ₄ of the valve 16 is small, so that the control plates 30 ₁ to 30 ₄ are connected to the coil springs 31 to 31. The openings 16 ₁ to 1 are opened by the spring force of
6. It is held in a state in which it protrudes by a predetermined amount within ₄ (the state shown in FIG. 6). As a result, the opening 1
As the opening areas of the rotary valves 6 ₁ to 16 ₄ become smaller, the open period of the rotary valve 16 becomes a relatively short predetermined period T ₁ ' as shown in FIG. On the other hand, when the engine speed exceeds the predetermined speed _N1 and gradually shifts to the high speed side, the centrifugal force gradually increases as the rotation of the rotary valve 16 increases. ₁ to ₃₀₄ are moved backward along the slanted guide groove 16c, and the opening period of the valve 16 gradually becomes longer as shown by the symbol A in the figure. Further, when the engine speed increases and reaches the predetermined speed _N2 on the high speed side shown in the same figure, the valve opening period control plates 30 ₁ to 30 increase due to the significant increase in the centrifugal force. ₄ is moved to the retreat end, and the open period of the rotary valve 16 is maintained at the maximum period T ₁ ″ (period corresponding to the fully open state).

Therefore, in a high-speed, high-load region of the engine 1 where the opening periods of both the rotary valve 16 and the intake valve 7 almost completely overlap, the opening period of the rotary valve 16 is reduced as shown by the symbol B in FIG. As the period T ₁ ″ becomes longer, sufficient intake air volume is obtained to ensure the required engine output.And,
In the low rotation and low load region, especially in the idle region, where the above overlap period is zero or almost zero,
As shown by reference numeral C in the figure, the opening period T ₁ ' of the rotary valve 16 is shortened, and the intake air amount is reduced to a desired amount corresponding to the idle region or the like. In other words, in this engine 1 (NA Miller cycle engine), as in the conventional engine shown by the chain line in the same figure, the open period of the rotary valve 16 during idle, etc. is equal to the valve open period T ₁ '' in the high rotation and high load region. If the lengths are set to be the same, it will be difficult to reduce the intake air amount to the desired amount due to the large dead volume existing between the rotary valve 16 and the combustion chambers ₄₁ to ₄₄ . However, by shortening the opening period of the valve 16 as described above, this problem can be avoided and the engine speed can be lowered to the desired idle speed. As a result, sufficient output performance is ensured in the high-speed, high-load range, etc., and the idling state, fuel efficiency, etc. are effectively improved.

Although the above embodiment is an application of the present invention to a so-called NA Miller cycle engine, other than this type of engine, a similar configuration may be applied to an engine equipped with a cylindrical rotary valve. It is possible to apply Further, in the above embodiments, the present invention is applied to an engine equipped with a carburetor, but it can also be applied to an engine equipped with a fuel injection nozzle.

[Brief explanation of drawings]

1 to 8 show embodiments of the present invention, in which FIG. 1 is a cutaway plan view of essential parts of an engine to which the present invention is applied, and FIG. 2 is a sectional view taken along the line of FIG. 1. FIG. 3 is a time chart showing the operation of the above embodiment, FIG. 4 is a graph showing the opening/closing operation characteristics of the shutter valve and rotary valve with respect to the accelerator opening, FIG. 5 is a partially cutaway perspective view of the rotary valve, and FIG. Fig. 6 is an enlarged sectional view taken along the line of Fig. 5, Fig. 7 is a graph showing the valve opening period characteristics of the rotary valve with respect to engine speed, and Fig. 8 is a time chart showing the effects of the above embodiment. It is. Moreover, FIG. 9 is a schematic explanatory diagram showing the problems of the conventional technology. 1...Engine, 15 ₁ to 15 ₄ ...Intake passage (primary side intake passage), 16...Rotary valve, 1
6 ₁ to 16 ₄ ... opening, 30 ₁ to 30 ₄ ... valve opening period control plate, 31, 31 ... elastic member (spring).

Claims (1)

[Scope of utility model registration request] An intake system for an engine having a cylindrical rotary valve having an opening through which intake air passes, and configured to control the opening/closing timing of an intake passage by the rotary valve, the rotary valve as described above. A valve opening period control plate that changes the opening period of the valve by protruding and retracting with respect to the opening of the valve, and an elastic member that biases the control plate in the direction of protruding are provided. An intake system for an engine, characterized in that the direction of movement of the valve period control plate is inclined with respect to the circumferential direction of the rotary valve so that the valve period control plate is retracted by centrifugal force generated as the rotary valve rotates. .