JPS63243414A - Dohc engine - Google Patents

Abstract

PURPOSE:To prevent a mechanism unnecessary upon rest of one of two valves from being an engine load by providing a stopping mechanism for releasing one of two camshafts from a rotary drive system and interrupting the motion thereof in an engine fitted with two or more intake and exhaust valves per cylinder. CONSTITUTION:Two intake ports 4a and 4b are formed from the left side of the center line P of cylinder arrangement toward the inside of a cylinder 3, and ports 5a and 5b at the side of the cylinder 3 are positioned symmetrically right and left about the center line P. Also, the first intake port 4a is made a swirl port and the second intake port 4b straight port. Furthermore, for each cylinder 3, two exhaust ports 6a and 6b are formed in inverse relation to the intake ports 4a and 4b, and intake valves 8a and 8b for opening and closing the right and left intake (exhaust) ports 4a and 4b are opened and closed with the left camshafts 10a and 10b. One of the camshafts 10b is made releasable from a rotational drive system via a stop mechanism fitted to the end thereof, when an engine is operating under a low load.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to a DOHC structure having two camshafts and two or more intake valves per cylinder.
The present invention relates to HC engines, and in particular to technology for changing the movement of a valve system depending on the operating state of the engine.

(Prior art) Multi-valve type, such as a 3-valve type in which one cylinder has two intake valves and one exhaust valve, and a four-valve type in which one cylinder has two intake valves and two exhaust valves. 2. Description of the Related Art Engines are known in which the movement of a valve system is changed depending on the operating state.

During high-speed, high-load operating conditions, all intake and exhaust valves are opened and closed to obtain high output. In low-speed, low-load operating conditions, the intake valve, or part of the intake valve and exhaust valve, remains closed, and the remaining valves perform air intake and exhaust. The intake valve that continues to operate is one that is provided in a swirl port that is configured to actively induce intake swirl. In other words, at low engine speeds and low loads, the flow rate of intake air is increased to actively utilize swirl and intake inertia effects to lower fuel consumption and stabilize idle rotation.

Conventionally, as a mechanism for stopping the opening/closing operation of some valves as described above, a mechanism for transmitting driving force has been provided between a camshaft and a rocker arm.

(Problems to be Solved by the Invention) In the above-mentioned conventional configuration, even if some valves do not open for a while, the camshafts associated with those valves are constantly rotating, which increases the load on the engine. It has become.

Therefore, although the load can be reduced to some extent by stopping the opening and closing of the valves, the camshaft, which is a major component of the valve drive system, continues to rotate, so the effect of reducing the load is extremely small.

This invention was made to address the above-mentioned conventional problems, and its purpose is to prevent unnecessary mechanical parts from placing a load on the engine when the opening/closing operations of some valves are suspended. The goal is to provide the best of both worlds.

(Means for Solving the Problems) The DOHC engine of the present invention that achieves the above object has two camshafts A and B arranged parallel to the cylinder arrangement direction, and one camshaft B that rotates. a stop mechanism for separating the cylinders from the drive system and stopping them; a first intake valve corresponding to the swirl bow 1 for actively inducing intake swirl for each cylinder and opened and closed by the camshaft 8; It includes a second intake valve that is opened and closed by the force shafts 1 to B, and an exhaust valve that is opened and closed by the camshaft A.

(Function) When both the force shafts i-A and 8 are rotated, the first intake valve, the second intake valve, and the exhaust valve are all opened 111. When the above-mentioned power valve A/F1-F3-8 is stopped by the above-mentioned stop mechanism at low rotation speeds and low loads, the above-mentioned second intake valve rests in the open state, and the above-mentioned first intake valve and exhaust valve are stopped. It opens and opens.

(Embodiment) Fig. 1 shows the structure of a Dot-IC nozzle according to an embodiment of the present invention, (A) shows the layout structure of the cylinder 3 and four boats in the cylinder head 1, and (B) shows the layout structure of the cylinder 3 and four boats in the cylinder head 1. ) is a XX sectional view in (A), and (C)
(A) is a YY cross-sectional view at (B).

In FIG. 1, J3 is shown, 1 is a cylinder head, 2 is a cylinder block, and 3 is a cylinder. A plurality of cylinders 3 are arranged in series, and P indicates the center line of the cylinder arrangement.

As shown in Figure 1 (A), from the left side of the center line P, the cylinder 3
A first intake boat 4a and a second intake boat 4b are formed inwardly, and a cylinder side port 5a of the first intake boat 4a is formed.
The cylinder-side opening 5b of the second intake boat 4b is located at a symmetrical position with respect to the center line P. The first intake boat 4a is helically bent toward the opening 5b, and serves as a swirl port that generates a strong swirl within the cylinder 3. The second intake boat 4b is formed substantially straight toward the frontage 5b, and is a straight boat that hardly generates swirl.

Further, first exhaust bows 1 to 6a and a second exhaust boat 6b are formed from the right side of the center line P toward the cylinder 3, and the first
Cylinder side lower a and second exhaust boat i of the exhaust boat 6a
-6b and the cylinder side lower b are disposed at symmetrical positions with respect to the center line P. In other words, on the right side of the center line P, there is a first
The frontage 5a of the intake boat 4a and the open lower a of the first exhaust boat 6a are arranged side by side, and a second
The lower b is arranged in parallel between the opening 5b of the intake boat 4b and the second exhaust boat 6b. This layout is characteristic of the present invention; in a typical 4-valve structure, two intake boat openings are located on one side of the center line of the cylinder arrangement, and two t)F air intake ports are located on the opposite side. The opening of the boat is located.

Further, the opening 5a of the first intake boat 4a is opened and closed by the first intake valve 8a, the opening 5b of the second intake port 4() is opened and closed by the second intake valve 8b, and the opening 7a of the first exhaust boat 6a is opened and closed by the first intake valve 8a. The opening lower b of the second exhaust valve 1-6il is opened and closed by the second exhaust valve 9b. Each valve 8a, 8b,
A valve spring 11, a cam floor cap 12, etc. are provided at 9a and 9b.

Further, above the cylinder head 1, a first camshaft 10a is arranged on the right side of the center line P of the cylinder arrangement, and a second camshaft 10b is arranged on the left side, symmetrically with respect to the center line P and parallel to the center line P. has been done.

The cam floor caps 12 of the first intake valve 8a and the first exhaust valve 9a are in contact with the first camshaft 10a (corresponding to the camshaft Δ), and the second camshaft 10b (corresponding to the camshaft Δ)
(corresponding to camshaft B) has a second intake valve 8b and a second intake valve 8b.
The cam floor cap 12 of the exhaust valve 9b is in contact with it. That is, the first intake valve 8a and the first exhaust valve 9a are driven to open and close by the rotation of the first camshaft 10a, and the second intake valve 8b is driven by the second camshaft 10b.
and the second exhaust valve 9b are driven to open and close.

The first camshaft 10a and the second camshaft 1ob are rotationally driven in synchronization with the rotation of the crankshaft,
A stopping mechanism described later is attached to the second camshaft 10b, and the second camshaft 10b can be stopped at a predetermined angular position by hydraulic control.

In high rotation/high load operating conditions, the first camshaft 1
Both the oa and the second camshaft 10b rotate, and the two intake valves 3a, 8b and the two exhaust valves 9a
, 9b all open and close, drawing out the high output of the engine. In low rotation/low load operating conditions, the second intake valve 8b
With the second exhaust valve 9b and the second exhaust valve 9b closed, the second camshaft 10b is stopped by the stop mechanism, and only the first camshaft 10a rotates. That is, only the first intake valve 8a and the first exhaust valve 9a operate, and only the first intake boat 4a and the first exhaust boat 6a function effectively. The first intake boat 4a is a swirl port as described above, and generates a large intake swirl in the cylinder 3, creating an effective combustion state in low rotation and low load conditions, stabilizing idle rotation and fuel consumption rate. Contributes to the reduction of

Note that the first camshaft 10a and the second camshaft 10
The valve timing characteristics of (b) are also different. In the second camshaft 10b, which rotates only at high speeds and high loads, the valve overlap is set appropriately. On the other hand, the first camshaft 10a, which operates independently at low rotations and low loads, has no valve overlap. This allows appropriate intake and exhaust operations to be performed at low speeds and low loads and at high speeds and high loads.

Next, the above-mentioned stopping mechanism for stopping the second camshaft 1ob at a predetermined angular position will be explained.

As shown in FIG. 2, one end of the second camshaft 10b is supported by a journal 13, and a short input shaft 14 is fitted to the shaft end of the second camshaft 10b.
A sprocket 15 is attached to the sprocket 15. The rotation of the crankshaft is transmitted to this sprocket 15, and the sprocket 15 and input shaft 14 constantly rotate during engine operation.

Input shaft 14, camshaft 10b and journal 1
3 has bottle holes aligned at a certain angular position,
An inner bottle 16, a middle bottle 17, and an outer bottle 18 are slidably set in these bottle holes. The inner bottle 16 on the input shaft 14 side is urged in the protruding direction by a spring 19, and when the bottle holes are aligned, the inner bottle 16 is pushed into the middle bottle 17.
It acts to push outward. Further, hydraulic pressure from an oil pump 20 is applied to the back of the outer pin 18 under the control of a solenoid valve 21. Outer bottle 1
When hydraulic pressure is applied to 8, the outer bottle 18 is urged inward, and acts to push the inner bottle 17 inward when the bottle holes are aligned.

In the state shown in FIG. 2, the middle bin 17 is connected to the input shaft 1
It is fitted into both the bottle hole of 4 and the camshaft hole, and now the input shaft 14
and the camshaft 10b are rotationally connected. That is, the camshaft 10b rotates integrally with the sprocket 15. To maintain this state, hydraulic pressure is applied to the outer bin 18, and when the middle bin 17 and the outer bin 18 are aligned, the force of the spring 19 prevents the middle bin 17 from coming out from the bin hole of the input shaft 14. Insert the inner bottle 17 from the outside into the outer bottle 1.
Push in with 8.

FIG. 3 shows the operation of stopping the rotating camshaft 10b at a predetermined position. In (A), oil pressure is applied to the outer bin 18 and the middle bin 17 is pushed into the input shaft 14 side. When the hydraulic pressure is released from the back of the outer bin 18 as shown in (B), when the middle bin 17 rotates to the outer bin 18 position, the force of the spring 9 is applied to the inner bin 16, the middle bin 17,
Joining the outer bottle 18, the inner bottle 17 pushes the outer bottle 18 and enters the pin hole of the journal 13 as shown in (C).
A medium bottle 17 comes out from the bottle hole of the input shaft 14.

Then, the rotation of the input shaft 14 is the rotation of the camshaft 10.
b, and the second intake valve 8b and the second exhaust valve 9b are stopped at the closed angular position.

Further, as shown in FIG. 2, the solenoid valve 21 is controlled by a control unit 22. Based on the intake air amount information from the air flow meter 23, the control unit 22 applies hydraulic pressure to the outer bin 18 during high load operation when the intake air amount is at a predetermined level or higher, and controls the second camshaft 10b.
Rotate.

When the intake air amount is below a predetermined level, the hydraulic pressure at the back of the outer bin 18 is released, and the second camshaft 10b is stopped at a predetermined position.

FIG. 4 shows another embodiment of the above-mentioned stopping mechanism. An input shaft 14 is fitted onto the outer peripheral side of the shaft end of the camshaft 10b, and the input shaft 14 is supported by the journal 13. A pin hole along the axial direction is formed at the center of the input shaft 14 and the camshaft 10b, and a keyed pin 24 is set in the pin hole of the camshaft 10b so as to be slidable in the axial direction. A spring 26 and a push bottle 25 are set in the bottle hole. When hydraulic pressure is applied to the back of the keyed bottle 24 from the oil passage 27, the keyed bottle 24 is displaced to the left against the force of the spring 260, and a part of the key of the keyed bottle 24 is moved to the input shaft 14.
engages with the keyway.

In this state, the camshaft 10b rotates together with the input shaft 14. To stop the camshaft 10b,
The hydraulic pressure at the back of the keyed bottle 24 is released from the oil passage 27. Then, the push bottle 25 and the keyed bottle 24 are pushed to the right by the force of the spring 26, and a portion of the key of the keyed bottle 24 is disengaged from the keyway of the input shaft 14. With this, even if the input shaft 14 rotates, the camshaft 10b does not rotate.

In the embodiment shown in FIG. 1, there are two exhaust ports, but there may be only one exhaust port, in which case one exhaust valve is opened and closed by the first camshaft that is constantly rotating.

(Effects of the Invention) As explained in detail above, in the DOHC engine according to the present invention, the two camshafts are rotated to open and close the two intake boats during high loads, and one camshaft is opened and closed during low loads. By stopping the rotation of one camshaft, only one intake valve can be opened and closed, and the appropriate engine characteristics can be brought out according to the operating conditions.At the same time, when the load is low, the rotation of one camshaft itself is stopped, allowing some valves to be opened and closed. Since the movement is stopped, unnecessary mechanical load on the engine output in that state is reduced, and high efficiency of the engine can be realized.

[Brief explanation of drawings]

FIG. 1(A) shows a cylinder and 4 in one embodiment of the present invention.
Plan explanatory diagram showing the layout of two boats, same figure (B)
is a XX cross-sectional view of (A), and (C) is a cross-sectional view of (A) and (
8), FIG. 2(A) is a vertical sectional view of the first embodiment of the camshaft stop mechanism, and FIG.
), FIG. 3 is an explanatory diagram of the operation of the above stopping mechanism, and FIG. 4 is a longitudinal sectional view of a second embodiment of the camshaft stopping mechanism. 1...Cylinder head 2...Cylinder block 3...
...Cylinder 4a...First intake boat 4b...Second intake boat 6a...First exhaust boat 6b...Second exhaust boat 8a... ...First intake valve 8b...Second intake valve 9a...First exhaust valve 9b...Second exhaust valve 10a...First camshaft 10b ...Second camshaft 13...Journal 14...Input shaft 15...Sprocket Patent applicant Mazda Corporation Representative Patent attorney - Kensuke Shiro
Patent Attorney Masatoshi Matsumoto Figure 2 (A) (B) Figure 3 (A) (B) (
C) No. (A), IOa ri? (C) Y-Y curved surface

Claims (1)

[Claims] (1) Two camshafts A and B arranged parallel to the cylinder arrangement direction, a stop mechanism for separating and stopping one camshaft B from the rotational drive system, and a positive control mechanism for each cylinder. a first intake valve that corresponds to a swirl port that induces intake swirl and is opened and closed by the camshaft A; a second intake valve that is opened and closed by the camshaft B; and a second intake valve that is opened and closed by the camshaft B; DOH equipped with an exhaust valve that is opened and closed by
C engine.