JPH0355644B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a valve timing control device for an engine, and particularly to a valve timing control device for an engine, which is provided with a pair of intake ports for one cylinder, and which is controlled by a pair of intake valves having different opening periods. It relates to something that opens and closes at a predetermined timing.

Conventionally, as disclosed in, for example, Japanese Unexamined Patent Publication No. 56-44404, a pair of intake ports are provided for one cylinder of an engine, and a pair of intake ports are provided that open and close each intake port at predetermined timings. Those equipped with an intake valve are known. Compared to the conventional one, which has a single intake port for one cylinder and a single intake valve that opens and closes the intake port, the effective opening area of the intake port can be increased, and the intake air can be This is preferable in terms of improving engine output because it can increase the charging efficiency of the engine.

In an engine equipped with such a pair of intake ports and a pair of intake valves, in order to improve the filling efficiency of intake air at high loads while not impairing the combustibility at low loads of the engine, the above-mentioned measures are taken. The opening periods of a pair of intake valves are made to differ, and the intake valve with the longer opening period is set to have a longer overlap period with the exhaust valve, and both intake valves are closed almost simultaneously at the end of the intake stroke. By doing so, when the intake air amount is small and the intake air inertia speed is slow, the engine is operated at low rotation speeds and high loads, preventing intake air from blowing back, improving charging efficiency, and reducing the total overlap period between the above-mentioned pair of intake valves and the exhaust valve. It is conceivable to make the length as short as possible to keep the ratio of residual exhaust gas to a small value and to ensure good combustibility.

However, while this method can ensure combustibility when the engine is under low load and improve output when the engine is under high load and under high load, on the other hand, when the engine is under high load and high speed, the amount of intake air is large and the inertia speed of the intake air is low. Due to the high speed of the engine, there is a disadvantage that the intake air filling efficiency cannot be sufficiently improved at high loads and high rotations when the ratio of residual displacement is small and blowback of intake air is difficult to occur.

Therefore, the present invention has been made in view of the above-mentioned problems, and in an engine equipped with a pair of intake ports and a pair of intake valves as described above, the above-mentioned pair of intake ports are operated at low load and high load and low rotation of the engine. By effectively lengthening the total opening period of the pair of intake valves when the engine is under high load and at high speed, while minimizing the total overlap period between the valves and the exhaust valve, The purpose of this is to make it possible to sufficiently improve output performance by significantly improving charging efficiency from high load and low rotation to high load and high rotation of the engine, without impairing the combustibility of the engine. be.

In order to achieve this object, the configuration of the present invention is such that a pair of intake ports are opened and closed by a pair of intake valves having different opening periods, and the intake valve with a longer opening period of the pair of intake valves is replaced with an exhaust valve. In an engine that is set to have a long overlap period with the intake valve, the valve train that controls the opening and closing of the intake valve with the shortest opening period out of the pair of intake valves, when the engine is under high load and high speed, the valve of the intake valve is It is equipped with a variable mechanism that controls the timing to be shifted to the delayed side. As a result, while increasing the effective opening area of the pair of intake ports, when the engine is under low load or high load and low speed, the intake valve is dominated by the long opening period, and the total overlap period with the exhaust valve is shortened. On the other hand, when the engine is under high load and speed, the intake valve is dominated by the intake valve, which has a short opening period, and the total valve opening period is lengthened.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIGS. 1 and 2 show an embodiment in which the present invention is applied to a so-called four-valve four-cylinder engine, which has a pair of intake valves and a pair of exhaust valves for one cylinder. In the figure, 1 is the engine body, 2
A to 2d are first to fourth cylinders formed in series along the center line l of the engine body 1, and each cylinder 2a to 2d has a first and second pair of intake ports 3a, respectively. , 3b and a pair of first and second exhaust ports 4a, 4b. The first and second intake ports 3a and 3b in each cylinder 2a to 2d are on one side (intake side) of the engine body 1.
The first opening in each cylinder 2a to 2d is opened in parallel in a direction substantially parallel to the engine body center line l direction (cylinder row direction) of the cylinders 2a to 2d.
And the second exhaust ports 4a, 4b are connected to the cylinders 2a to 2d from the other side (exhaust side) of the engine body 1.
The intake ports 3a, 3b and the exhaust ports 4a, 4b are arranged to face each other across the engine body center line l. . Furthermore, the second intake port 3 of the first cylinder 2a and the second cylinder 2b
b and 3b, between the second exhaust ports 4b and 4b, and between the third cylinder 2c and the fourth cylinder 2d.
The intake ports 3b, 3b and the second exhaust ports 4b, 4b are arranged adjacent to each other, back to back.

Further, the first and second intake ports 3a and 3b in each of the cylinders 2a to 2d are provided with a pair of first and second intake valves 5a and 5b that open and close the intake ports 3a and 3b at predetermined timings, respectively. They are arranged side by side on the intake side of the engine body 1, and the first and second exhaust ports 4a, 4b in each of the cylinders 2a to 2d have ports that open and close the exhaust ports 4a, 4b at predetermined timings. 1
and a second pair of exhaust valves 6a, 6b are arranged side by side on the exhaust side of the engine body 1, so that on the intake side of the engine body 1, the first cylinder 2a
The second intake valves 5b, 5b of the second cylinder 2b and the second intake valves 5b, 5b of the third cylinder 2c and the fourth cylinder 2d are adjacent to each other, and on the exhaust side of the engine body 1, Second exhaust valves 6b, 6b of the first cylinder 2a and second cylinder 2b, and second exhaust valves 6 of the third cylinder 2c and fourth cylinder 2d
b and 6b are adjacent to each other.

On the other hand, 7 is a first valve mechanism that is disposed on the intake side of the engine body 1 and controls the opening and closing of the first and second intake valves 5a and 5b in each cylinder 2a to 2d. 7 has a first camshaft 8 disposed on the intake side of the engine body 1 in parallel with the engine body center line l and rotationally driven by a crankshaft (not shown) of the engine; The first of each cylinder 2a to 2d,
Cam surfaces 8a, 8 corresponding to second intake valves 5a, 5b
b is formed. As shown in FIG. 3, the cam surfaces 8a and 8b are arranged so that the cam surface 8a corresponding to the first intake valve 5a is oriented in the rotational direction of the camshaft 8 from the top of the cam with respect to the cam surface 8b corresponding to the second intake valve 5. X
The rotation of the first camshaft 8 causes the first intake valve 5 in each cylinder 2a to 2d to be larger.
After the first intake valve 5a is opened, the second intake valve 5b is opened, and the first and second intake valves 5a and 5b are controlled to close almost simultaneously. The opening periods of the two valves are made different so that the opening period of the valve 5b is shortened, and the first intake valve 5a, which has a long opening period, is configured to have a long overlapping period with the exhaust valves 6a and 6b. Reference numeral 9 denotes a second valve mechanism that is disposed on the exhaust side of the engine body 1 and controls opening and closing of the first and second exhaust valves 6a and 6b in each of the cylinders 2a to 2d. 9 has a second camshaft 10 disposed on the exhaust side of the engine body 1 parallel to the engine body center line l and rotationally driven by a crankshaft (not shown) of the engine. is each cylinder 2a~2
Cam surfaces 10a and 10b corresponding to the first and second exhaust valves 6a and 6b of d are formed in the same shape, and the rotation of the second camshaft 10 causes each cylinder 2a to
2d, the first and second exhaust valves 6a and 6b are controlled to open and close simultaneously with the same valve opening period.

Further, the first valve mechanism 7 includes a first cylinder 2.
Adjacent second intake valves 5 of a and second cylinder 2b
Two first variable mechanisms 11, 11 are provided that respectively variably control the valve timings of the second intake valves 5b, 5b and the adjacent second intake valves 5b, 5b of the third cylinder 2c and fourth cylinder 2d, and The second valve mechanism 9 includes two adjacent second exhaust valves 6b, 6b of the first cylinder 2a and the second cylinder 2b, and both adjacent second exhaust valves of the third cylinder 2c and the fourth cylinder 2d. 6
Two second variable mechanisms 12, 12 are provided to variably control the valve timings of valves b and 6b, respectively.

As shown in enlarged detail in FIG. 4, the first variable mechanism 11 is in contact with the cam surfaces 8b, 8b of the first camshaft 8 at one end (upper end) and the second
Two cylindrical tappet members 13, 13 that come into contact with the valve stems of the intake valves 5b, 5b, and two fitting holes 14a, 14a into which the tappet members 13, 13 are fitted and held so as to be slidable in the vertical direction. It also has an arcuate sliding surface 14b on its lower surface that is slidably guided by the arcuate guide surface 1a formed on the engine body 1, and is rotatably supported with respect to the first camshaft 8. A bucket-shaped rotating member 14 that rotates around the first camshaft 8 with the guidance assistance of the guide surface 1a, and a bucket-shaped rotating member 14 that rotates the rotating member 14 at a specific angle of the first camshaft 8 according to the operating state of the engine. The rotating member 14 is supported by the first camshaft 8. Divided into upper and lower parts, bolt 16,
16 and are integrally connected. Further, the operating device 15 is disposed parallel to the center line l of the engine body, bridges the two first variable mechanisms 11, 11, and connects the upper ends of both rotating members 14, 14. , 14, and the center line l of the engine body 1 in the direction of the center line l.
a reciprocating shaft 18 disposed perpendicularly to the reciprocating shaft 18 that engages with the reciprocating shaft 17 to swing the reciprocating shaft 17; The outputs of a rotation speed sensor 20 that detects the rotation speed of the engine and a load sensor 21 that detects the load state of the engine are input to the drive motor 19. When the load rotates at high speed, the reciprocating shaft 18 is moved to the right in FIG. 2 by the operation of the drive motor 19, and the swing shaft 17 is moved in the same direction as the rotational direction X of the first camshaft 8 (clockwise in FIG. 2). By rotating, the rotating members 14, 14 are rotated in the same direction as the rotating direction X around the first camshaft 8. As described above, when the engine is under high load and rotates at high speed, the operating device 15 causes the rotating members 14, 14 to rotate in the same direction as the rotational direction 8b, 8b and tappet member 1
The contact position with one end of the first camshaft 8 changes to the delayed side with respect to the rotational direction It is configured to control to shift to the delay side.

Further, the second variable mechanism 12 is made of the same constituent members as the first variable mechanism 11 (the constituent members of the first variable mechanism 11 are represented by adding a '' (dart) to the reference numerals), Two tappet members 13', 13' which come into contact with the cam surfaces 10b, 10b of the second camshaft 10 at one end and come into contact with the valve stems of the second exhaust valves 6b, 6b at the other end; A rotary member 14' that is inserted and held in the insertion holes 14'a and 14'a and rotates around the second camshaft 10, and the rotary member 14' is rotated according to the operating state of the engine. and an operating device 15'. The operating device 15' has two second
A swing shaft 17' that connects both rotating members 14', 14' of the variable mechanisms 12, 12 at their upper ends, and a reciprocating shaft shared by the first variable mechanism 11 that swings the swing shaft 17'. 18, and a drive motor 19 that is also shared with the first variable mechanism 11 that reciprocates the reciprocating shaft 18. Therefore, when the engine is under high load and rotates at high speed, the reciprocating shaft 18 is moved by the operation of the drive motor 19. By rotating the swing shaft 17' in the same direction as the rotation direction X of the second camshaft 10, both the rotation members 14', 14' are rotated in the rotation direction Rotate in the same direction,
Cam surfaces 10b, 10b and tappet members 13', 1 for a specific angular position of the second camshaft 10
The contact position with one end of 3' is set by the second camshaft 10.
to the lag side with respect to the rotation direction X, and each second
This is to control the valve timing of the exhaust valves 6b, 6b to be delayed.

In addition, without bringing the lower end of the tappet member 13 or 13' into direct contact with the valve stem of the second intake valve 5b or the second exhaust valve 6b as shown in FIG. 2, the hydraulic tappet device A as shown in FIG. It is preferable to intervene. In other words, the hydraulic tappet device A is
Cam surfaces 8b, 10 of camshaft 8 (or 10)
The rotating member has a circular blocking portion 23a that slides in contact with the rotating member b, and a first communication hole 23b that extends perpendicularly from the outer periphery of the blocking portion and communicates with the oil passage 22 provided in the rotating member 14, 14'. A cylindrical tapepet member 23 having a side portion 23c that slides in the fitting holes 14a, 14'a of 14, 14', a side wall 24a fitted into the inner periphery of the tapepet member 23, and a suction
A cylindrical first member 24 including a bottom wall 24b that contacts the valve stems of the exhaust valves 5b, 6b and disposed in a direction opposite to the direction of the tappet member 23, and the tappet member 23 and the first member 24. During this time, the outer periphery of the spring 25 slides into contact with the inner periphery of the first member 24, and the tip of the spring 25 contacts the closed portion 23a of the tapepet member 23.
One end side (upper side) of the tapepet member 23 is connected to the first communication hole 23b through a cutout groove 23d formed in the closure part 23a of the tapepet member 23. While forming a reservoir chamber 26, the other end side (lower side) is a first member 24.
A second hydraulic pressure chamber 27 is formed with the bottom wall 24b of the hydraulic pressure chamber 27, and the second communication hole 28a is provided in the center to communicate the oil reservoir chamber 26 and the hydraulic pressure chamber 27.
The member 28 is built in the hydraulic pressure chamber 27, and when the internal pressure of the hydraulic pressure chamber 27 suddenly increases due to the pressing force of the cam surfaces 8b and 10b of the camshafts 8 and 10, the valve closes and the second valve is closed. While the communication hole 28a is closed, at other times it is opened and the second communication hole 2 is closed.
The second communication hole 28a is opened and closed according to the pressure difference between the oil reservoir chamber 26 and the hydraulic pressure chamber 27 to control the amount of oil in the hydraulic pressure chamber 27. By changing the closed portion 23a of the tappet member 23, the cam surfaces 8b, 10
(b) so that the cam force is always in sliding contact with the valve stem, and the cam force is transmitted to the valve stem without creating any valve clearance even when the engine is running at high speed.

In FIG. 1, reference numeral 30 denotes a bearing portion that rotatably supports the first and second camshafts 8, 10, and the bearing portion 30 is a bearing portion that rotatably supports the first and second camshafts 8, 10.
Each rotating member 14, 14, 14', 1 of 1, 12
4' and to suppress the deflection of the first and second camshafts 8, 10 as much as possible at both ends and the center of the engine body 1 in the direction of the center line l. Further, in FIG. 2, 31 is a valve spring that biases each intake and exhaust valve 5a, 5b, 6a, 6b in the valve closing direction, and 32 is a valve guide.

Next, regarding the operation of the above embodiment, when the engine is under low load or high load and low rotation, the first and second variable mechanisms 11 and 12 are in an inactive state, and the first and second variable mechanisms 11 and 12 in each cylinder 2a to 2d are in a non-operating state. Second intake valves 5a, 5b and first and second exhaust valves 6a, 6b
The respective valve timings are controlled by the first and second valve operating mechanisms 7 and 9, respectively, and as shown by solid lines in FIG. 6, the first and second exhaust valves 6a,
6b both open near the bottom dead center of the piston and then close near the top dead center to perform the exhaust stroke, and then the first and second intake valves 5a and 5b open near the top dead center and then close near the bottom dead center. Close it and perform the intake stroke. At that time, during high load and low rotation, the intake air flows through the first and second
From a pair of intake ports 3a, 3b to each cylinder 2a~
2d, the effective opening area of the intake port is increased compared to a single intake port, improving the intake air filling efficiency and improving the output of the engine. Moreover, the valve timings of the first and second intake valves 5a and 5b are determined by the first valve operating mechanism 7, so that the first intake valve 5a has a long opening period, the second intake valve 5b has a short opening period, and the first intake valve 5a has a short opening period. The first intake valve 5a opens first, then the second intake valve 5b opens, and then both close almost simultaneously. In other words, the overlap period between the first intake valve 5a, which has a long opening period, and the exhaust valves 6a and 6b becomes long. Since both intake valves 5a,
The total overlap period of the exhaust valves 5b with the exhaust valves 6a and 6b as a whole is made as short as possible, thereby reducing the amount of residual exhaust gas (dilution gas) brought in during low load of the engine with a small intake amount. In addition, it is possible to prevent intake air from blowing back at high load and low rotation speeds, and to ensure good combustion performance.

Furthermore, in this case, the first and second pair of exhaust ports 4a and 4b in each cylinder 2a to 2d are opened and closed by the pair of exhaust valves 6a and 6b, respectively, so the effective opening area of the exhaust port is also a single one. As a result, the scavenging efficiency of the exhaust gas is improved, and as a result, the filling efficiency of the intake air can be further improved.

On the other hand, when the engine is at high rotation speed and under high load, the first and second variable mechanisms 11 and 12 operate together, and each cylinder 2a to
2d, the valve timing of the second intake valve 5b, which has a shorter opening period among the pair of intake valves 5a, 5b, is delayed by the first variable mechanism 11, and the valve timing of the second intake valve 5b, which has a shorter opening period, is delayed by the first variable mechanism 11, and the valve timing of the second intake valve 5b, which has a shorter opening period, among the pair of intake valves 5a, 5b is delayed. The valve timing of the exhaust valve 6b is variably controlled so as to be shifted to the delayed side. As a result, in the intake stroke of each cylinder 2a to 2d, both intake valves 5a, 5b are adjusted by the amount of the delay side deviation of the valve timing of the second intake valve 5b.
The total valve opening period as a whole becomes longer without changing the opening area, and together with the increase in the effective opening area of the intake port, the intake air filling efficiency can be significantly improved, and therefore the engine that requires output can be Output performance under high loads can be greatly improved.

Furthermore, in this case, in the exhaust stroke of each cylinder 2a to 2d, both exhaust valves 6a, 6b are adjusted by the amount of the delay side deviation of the valve timing of the second exhaust valve 6b.
Since the total valve opening period as a whole becomes longer, together with the increase in the effective opening area of the exhaust port, the scavenging efficiency of the exhaust gas can be significantly improved, and in turn, the filling efficiency of the intake air can be further improved, It is possible to further improve output performance.

In addition, when the engine is under high load and at high speed, the amount of intake air is large and the inertial speed of the intake air is high.
Even if the total overlap period of the intake and exhaust valves 5a, 5b, 6a, and 6b becomes longer, or even if the opening period of the intake valve 5b lags into the compression stroke, the amount of residual exhaust gas brought in can be minimized. Since the amount of air can be reduced and blowback of intake air is less likely to occur, combustibility is not affected.

Further, the second intake valve 5b and the second exhaust valve 6
If the valve timing of b is variably controlled by the first and second variable mechanisms 11 and 12 so as to be gradually shifted to the retarded side as the engine shifts from low rotation to high rotation, a torque shock will occur during the transition. This is advantageous because variable control can be performed smoothly without any problems.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but also includes various other modifications. For example, in the above embodiment, a case has been described in which the present invention is applied to an engine equipped with a pair of intake ports 3a, 3b and a pair of intake valves 5a, 5b, but it can also be applied to a dual induction type engine. In this case, as shown in Figure 1,
The first intake port 3a with a small passage area is used as a low-load intake port, the second intake port 3b with a large passage area is used as a high-load intake port, and the high-load intake port has an opening/closing valve that opens and closes when the engine is under high load. A valve 33 is provided to supply intake air only from the low-load intake port (first intake port 3a) when the engine is under low load, and to supply intake air from the high-load intake port in addition to the low-load intake port when the engine is under high load. It is only necessary to supply intake air from the second intake port 3b as well, which makes it possible to achieve higher output by improving combustibility at low loads and improving charging efficiency at high loads, which the dual duct system has. You can further improve and demonstrate your abilities. It goes without saying that the present invention can also be applied to single-cylinder or other multi-cylinder engines.

Further, the second intake valve 5b and the second exhaust valve 6
In addition to the variable mechanisms 11 and 12 as in the above-mentioned embodiments, the variable mechanism for variable control of the valve timing in b may include a mechanism that changes the relative position of the output shaft of the engine and the camshaft, or a mechanism that slides the three-dimensional camshaft. Although various known means can be adopted, as in the above embodiment, the rotating members 14, 1 which fit and hold the tapepet members 13, 13'
4' is rotated around the camshafts 8, 10 to change the contact position between the cam surfaces 8b, 10b and one end of the tappet members 13, 13' with respect to a specific angular position of the camshafts 8, 10. , 12 are advantageous in that variable control of valve timing can be performed reliably with good responsiveness with a simple structure, and generates little noise.

Further, in the above embodiment, a pair of intake ports 3a, 3b and a pair of intake valves 5a, 5b in each cylinder 2a to 2d, and a pair of exhaust ports 4a, 4b.
and a pair of exhaust valves 6a, 6b are respectively arranged on the intake side and exhaust side of the engine body 1 and arranged parallel to the center line l direction, and the second intake valves 5b, 5b and the second exhaust valves 6b, 6b Although they are arranged adjacent to each other, it goes without saying that other arrangement configurations may be used. However, in the arrangement as in the above embodiment, the bearing portions 30, 30 of each camshaft 8, 10
The second intake valves 5b, 5b between the adjacent cylinders (2a and 2b, 2c and 2d) and the second exhaust valves 6b, 6b are connected to each other by one variable mechanism 11, without interfering with the three-point arrangement. This is advantageous because it can be controlled with 12 units.

As explained above, according to the present invention, a pair of intake ports are opened and closed by a pair of intake valves having different valve opening periods, and the intake valve with a longer opening period among the pair of intake valves is used as an exhaust valve. In an engine set to have a long overlap period,
When the engine is under high load and speed, the valve timing of the intake valve with the shortest opening period of the pair of intake valves is shifted to the delayed side to lengthen the total opening period of the intake valve without changing the opening area of the intake port. As a result, while ensuring good combustion performance at low engine loads, the intake air filling efficiency at high engine speeds and high loads can be significantly improved, resulting in an engine with excellent fuel efficiency and output performance. This makes it possible to provide the following.

[Brief explanation of drawings]

The drawings illustrate an embodiment of the present invention, and FIG. 1 is a plan view when applied to a four-cylinder engine, FIG. 2 is a vertical side view of FIG. 1, and FIG. 3 is a sectional view of the first camshaft. FIG. 4 is an enlarged perspective view of the variable mechanism part, FIG. 5 is a vertical sectional side view of the main part showing a modification of the tappet member part of the variable mechanism, and FIG. 6 is an explanatory diagram showing the valve timing of the intake and exhaust valves according to the present invention. It is. 2a to 2d...1st to 4th cylinders, 3a, 3b...
...Intake port, 4a, 4b...Exhaust port, 5
a, 5b...Intake valve, 6a, 6b...Exhaust valve,
7, 9... Valve mechanism, 8, 10... Camshaft, 8a, 8b, 10a, 10b... Cam surface, 1
1...First variable mechanism, 12...Second variable mechanism.

Claims (1)

[Claims] 1. An engine in which a pair of intake ports are opened and closed by a pair of intake valves with different opening periods, and the intake valve with the longer opening period of the pair of intake valves is set to have a longer overlap period with the exhaust valve. In the valve train, which controls the opening and closing of the intake valve of the pair of intake valves that has a short opening period, a variable mechanism is provided to control the valve timing of the intake valve to be delayed when the engine is under high load and at high speed. An engine valve timing control device characterized by being provided with.