JPH021964B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates primarily to a four-stroke engine for automobiles. Previously, the present applicant has proposed a device of this type that includes at least two intake valves and at least two exhaust valves in one cylinder, and at least one
Tokkosho proposed a system in which the paired intake and exhaust valves stopped opening during low-load operation.
Publication No. 63-25170. This type of cylinder has at least two intake valves and at least two exhaust valves, compared to the conventional type in which only at least one intake valve is stopped, for example, in a low load range. Since it is difficult to cause exhaust recirculation or even intake air blow-through, it is possible to ensure high output when the engine is operating under high load, and optimal charging efficiency during low load operation, improving idle stability and fuel efficiency. can. The purpose of the present invention is to improve engine performance even further than this proposal, particularly to improve fuel efficiency and stability during low-load operation.One cylinder has two intake valves and two intake valves. A four-valve multi-valve type, in which one intake valve and exhaust valve are always opened and closed, and the other intake valve and exhaust valve are stopped from opening during low-load operation. In the engine,
The maximum lift amount and valve overlap between one of the intake valves and the exhaust valve, which are always open and closed, and the maximum lift amount and overlap amount between the other intake valve and exhaust valve, which stop opening during the low load operation. It is characterized by being smaller than.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 indicates one cylinder of the engine, which consists of two intake valves 3A, 3B on one side connected to each intake port 2, 2, and two intake valves 3A, 3B on the other side connected to each exhaust port 4, 4. Two exhaust valves 5A and 5B are provided. One 3A of the two intake valves 3A, 3B and the other 5A of the two exhaust valves 5A, 5B can be freely switched between operation and non-operation according to the operating condition of the engine,
For example, when the engine is operating at low load, the valve is inoperative, that is, the valve is not opened. The means for doing so is arbitrary, but for example, for the intake valve 3A, as shown in FIG. A control hydraulic cylinder 9 is provided on the side of the intake valve 3 to control the spring strength of the spring 10 below the fulcrum 8.
A spring 11 that can be variably switched depending on the strength of the spring 11 is used. To explain further, the hydraulic cylinder 9 includes a piston 12 that supports the spring 10 from below, and a hydraulic chamber 13 below the piston 12.
The interior of the chamber 13 is connected to a hydraulic passage 15 via a check valve 14.
and a discharge passage 17 via an electromagnetically operated control valve 16.
Thus, when the control valve 16 closes, the pressure inside the hydraulic chamber 13 becomes high, the spring 10 increases its spring strength, and the rocker arm 7 closes the valve 3A.
Then, when the control valve 16 is opened, the pressure in the chamber 13 decreases and the spring strength of the spring 10 decreases, causing the rocker arm 7 to move from its fulcrum. 8 moves downward to prevent the valve 3A from opening, and the control valve 16 controls the low load obtained from the throttle valve opening sensor and negative pressure sensor during low load operation such as low engine speed or idling operation. The solenoid 16a is excited and opened by the signal.

This is substantially the same for the exhaust valve 5A, that is, the control cylinder 21 described above is provided below the fulcrum 20 at the root of the rocker arm 19 interposed between the valve 5A and the exhaust cam 18. Both cylinders 9 and 21 were designed to operate in synchronization with each other.

The two intake valves 3A, 3B and the two exhaust valves 5
The valve timing and lift amount of A and 5B are set in two ways as follows.

(a) The valve opening/closing timing of a pair of intake valves 3A and exhaust valves 5A, which open and stop during low-load operation, and a pair of intake valves 3B and exhaust valves 5B, which open and close at all times, are the same, and only the lift amount is changed, for example. Reduce the latter by making the former 9mm and the latter 6mm. (See Figure 3) (b) The valve timing and lift amount of the pair of intake valves 3B and exhaust valves 5B are changed from those of the other pair of intake valves 3A and exhaust valves 5A. That is, as shown in FIG. 4, the opening timing of one pair of intake valves 3B and exhaust valve 5B is later than the other pair of intake valves 3A and exhaust valve 5A, and the valve closing timing is earlier.
Further, the lift amount of the valves 3B and 5B (for example, 6 mm) is made smaller than that of the valves 3A and 5A (for example, 9 mm).

In both cases (a) and (b), the valve timing of the intake valve 3A and exhaust valve 5A, which operate during high-load operation, should be such that high output can be obtained.For high-speed, high-output types, the exhaust valve 5A is sufficient. The valve should be opened early to exhaust air.

In case (b), the valve timings of the intake valve 3B and the exhaust valve 5B, which are always operated, are set to achieve low fuel consumption during low load. In other words, if the intake valve 3B is closed too late, the air-fuel mixture sucked into the combustion chamber will be returned to the intake system, and if it is closed too early, the air-fuel mixture will not be sucked in enough, reducing the inertial intake effect to the low-speed range. So that you can make the most of your
Set an appropriately early valve closing time. The opening timing of the exhaust valve 5B is set appropriately late because if it is opened early, the energy of the explosion stroke will not be obtained sufficiently as rotational force and will be blown through to the exhaust system. As described above, by reducing the lift amount of the intake valve 3B and exhaust valve 5B, which are constantly operated, the valve spring can be weakened accordingly, and the valve drive range is also reduced, which reduces friction and improves engine output. Both fuel efficiency and stability during idling are significantly improved, and by reducing valve overlap in conjunction with a reduction in lift amount, the inertia effect suitable for the low load range improves charging efficiency, improves scavenging efficiency, and improves energy consumption. It is possible to achieve an improvement in the recovery rate, and it is also possible to reduce the idle rotation speed, so that further improvement in fuel efficiency can be expected.

On the other hand, during high-load operation, the intake valve 3A and exhaust valve 5A operate in addition to the intake valve 3B and exhaust valve 5B, and the valve timing and lift amount are set to obtain high output as described above. Because of this, it is possible to obtain sufficient high output in the high load range.

In this way, according to the present invention, the maximum lift of one intake valve and exhaust valve, which are always open and closed, and the valve overlap, and the maximum lift of the other intake valve and exhaust valve, which stop opening and closing during low-load operation, are determined. Since it is smaller than the lift amount and overlap amount, all valves operate during high load operation to achieve high output and high rotation, and at the same time, in the low load range, the overlap is small and lift and opening are reduced. In addition to reducing the angle, it also has the effect of reducing intake air blow-by and exhaust gas backflow, ensuring stable low-load combustion.

[Brief explanation of drawings]

Fig. 1 is a partial perspective view of an example of the device of the present invention, Fig. 2 is an enlarged cross-sectional side view of the valve control mechanism, and Figs. 3 and 4 show the lift amount of the intake valve and exhaust valve, respectively. A timing diagram is shown. 1...Cylinder, 2...Intake pipe, 3A, 3B...
...Intake valve, 4...Exhaust pipe, 5A, 5B...Exhaust valve, 9, 21...Control cylinder.

Claims (1)

[Claims] 1. One cylinder is provided with two intake valves and two exhaust valves, and one of the intake valves and the exhaust valve is always operated to open and close, and the other intake valve and exhaust valve are opened and closed at all times. In a 4-valve multi-valve engine whose valve opening operation is stopped during low load operation, the maximum lift amount and valve overlap between the intake valve and exhaust valve, which are always open and closed, are determined during the low load operation. An intake/exhaust valve control device for a multi-valve engine, characterized in that the valve-opening operation of the intake valve and the exhaust valve are smaller than the maximum lift and overlap between the other intake valve and exhaust valve. 2. A patent characterized in that one of the intake valves and exhaust valves, which are always opened and closed, has a later opening timing and an earlier opening timing, respectively, than the other intake valve and exhaust valve, which stop opening and closing operations. An intake/exhaust valve control device for a multi-valve engine according to claim 1. 3. The multi-valve type according to claim 1, characterized in that the closing timing of one of the intake valves that is always opened and closed is set earlier than the closing timing of the other intake valve that stops the opening operation. Engine intake/exhaust valve control device.