JPS5925009A - Valve operation switching device of internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce the number of parts and decrease a manufacturing cost through formation of a device into a one-system switching mechanism, by supporting the locker arm of each of the suction valve and exhaust valve of a cylinder to a common locker shaft and integrally and simultaneously moving locker arms in the direction of an axis through the working of an actuator. CONSTITUTION:Locker arms 23 and 24 are rotatively and also axially movably mounted to a single locker shaft 25 disposed above a cam shaft 20, and axial movement thereof is controlled through movement of a switch ring 28 to selectively engage with either cams 21a, 22a for operation or cams 21b, 22b for recess. The integral and simultaneous movement, over the locker shaft 25, of the locker arms 23 and 24 of a suction valve 1 and an exhaust valve 2 permits the common use of a control system from an electromagnetic actuator 27, the switch ring 28, and springs 29 and 30, and further,simultaneous switching results in improvement of reliability and durability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to valve operation of intake valves and exhaust valves of cylinders that are switched between operation and deactivation during cylinder number control in which combustion in some cylinders of a multi-cylinder internal combustion engine is deactivated depending on engine operating conditions. The present invention relates to a valve operation switching device for switching.

When a vehicle such as a car is running under conditions that require high output, such as when accelerating or climbing, it is better to fill all cylinders of the engine with air-fuel mixture to obtain high output, but when the load is low, However, if all cylinders continue to operate, the filling rate of fresh air in each cylinder will decrease, resulting in poor combustion and increased pumping loss. Therefore, the concept of cylinder number control aims to improve fuel efficiency by concentrating the mixture in the remaining cylinders and reducing pumping losses by stopping the operation of some cylinders during low loads. already exists and is well known (see Japanese Patent Laid-Open No. 51104116).

) ° In the case of cylinder number control in a 4-cylinder engine, 2, >
':I J 笥;7. Due to deactivation, the combustion interval becomes longer by 3□, 0° in terms of crank angle, and torque fluctuation increases accordingly, but this can be greatly improved by replenishing the deactivated cylinders with fresh air for pressure regulation. Already confirmed by the applicant.

To briefly describe this torque fluctuation suppression method, as shown in FIG. 1, two cylinders that are switched between operating and inactive during cylinder number control are operated with the intake valve 1 open during the intake stroke and compressing the two cylinders. It provides the same opening characteristics of the intake and exhaust valves as in a normal 4-cycle, in which the exhaust valve 2 closes during the stroke and opens from the end of the expansion stroke to the exhaust stroke.
At rest, the exhaust valve 2 is always closed, and the intake valve 1 is slightly opened near the piston bottom dead center (either the suction bottom dead center, the expansion bottom dead center, or both). That is, the valve lift characteristics are set as shown in FIG.

According to this, the in-cylinder pressure of the dormant cylinder at the time when compression starts is always equal to the suction negative pressure of the operating cylinder, and after that, simple compression and expansion are repeated by raising and lowering the piston, and when controlling the number of cylinders, The in-cylinder pressure of each cylinder has a change characteristic as shown in FIG. The pressure change in the idle cylinders (#2, 3) is about half that of the operating cylinders (#1, 4) at its peak value, but
Since the pressure of the two idle cylinders changes synchronously every 360 degrees of crank angle, the change in engine torque appears to be good, but the torque changes generated from these two idle cylinders are combined.
Since the effect is doubled, it becomes possible to cope with the peak pressure level of the operating cylinder. Therefore, engine torque changes, including those of the operating cylinders, are obtained at every 180 degrees of crank angle, close to those due to the peak value of combustion pressure, and the smoothness of rotation is significantly improved.

In order to switch the valve operation of the intake and exhaust valves in this way when switching between operation and stop, it is rational to selectively use a pair of cams with different profiles, Examples of switching devices include those shown in FIGS. 4 to 6, for example.

To explain this, cams 5a and 5b with different profiles (the cam 5a is for use during operation, and the cam 5b is for use when at rest) are fixed adjacent to each other on the camshaft 4.

The rocker arm 6 is attached to the rocker shaft 7 so as to be movable in the axial direction, and is positioned via springs 11 and 12 between the rocker bracket 8 and a switching ring 10 that moves on the rocker shaft 7 by an electromagnetic actuator 9. Its movement in the axial direction is controlled by the movement of the switching ring 10, and it selectively engages with either one of the cams 5a, 5b.

For example, switching from operation to rest is performed using the electromagnetic actuator 9.
This is done by moving the switching ring 10 in the A direction. However, when the cam 5a is in contact with the rocker arm 6 and is driving it, the load of the valve spring 13 is added and the frictional force becomes extremely large, making it difficult to move the rocker arm 6 in the axial direction. In this state, even if the switching ring 10 moves in the A direction, the spring 12 is only compressed. Then, when the cam ridge portion of the cam 5a ends and a clearance is created at the contact surface with the rocker arm 6, the load of the valve spring 13 no longer acts.
The rocker arm 6 moves in the direction A by the acting force of the compressed spring 12, so that the cam 5b and the rocker arm 6 come to face each other.

Therefore, when stopping #2 and #3 cylinders in a four-cylinder engine, the valve operation is switched for the intake valve and exhaust valve of these cylinders, but even if each switching ring 10 is moved simultaneously by a single actuator 9, each rocker arm 6
move separately, and move one after another when a clearance is created between the contact surfaces of each rocker arm 6 and each cam 5a.

On the contrary, when switching from rest to operation, that is, when the switching ring 10 is returned to the direction B by the electromagnetic actuator 9, the action force of the compressed spring 11 causes the cam 5b to come into contact with the rocker arm 6. The rocker arm 6 is moved when a clearance is created between the surfaces.

Incidentally, since the #1.4 cylinder (not shown) is always in operation, the valve train may have a normal configuration (only the cam 5a and no switching mechanism).

However, in such a conventional valve operation switching device for controlling the number of cylinders, two rocker arms are provided for each cylinder, one for the intake valve and one for the exhaust valve, as shown in Fig. 4. were installed on different rocker shafts, so the control system from the actuator (
(switching rings, springs, etc.) are required, one system for the intake valve and one system for the exhaust valve.In addition to the problem of a large number of parts and high manufacturing costs, the valve operation of the intake valve and exhaust valve is Although they must be switched at the same time, since the control systems are separate for each system, there is no guarantee that they will switch at the same time, resulting in a lack of reliability and durability.

The present invention was made with the aim of solving these conventional problems, and includes a rocker arm that supports each drive rocker arm of the intake valve and exhaust valve of the cylinder that is switched between operation and rest on a single rocker shaft. At the same time, they are moved integrally and simultaneously in the axial direction by an actuator via a common control system.

Hereinafter, the present invention will be explained based on the drawings.

7 and 8 show an embodiment of the present invention.

(7) In the figure, 1 is an intake valve, 2 is an exhaust valve, and 13.14 is a valve spring that biases these valves 1.2 in the valve-closing direction.

The camshaft 20 includes a cam 21 for the intake valve 1, which has a cam 21a with a profile for when in operation and a cam 21b with a profile for when not in use, which are arranged side by side, and a cam 22a with a profile for when in operation. A cam 22b for the exhaust valve 2, which is provided adjacent to a cam 22b having a profile for use at rest, is fixed adjacent to the cam 22b.

23 is a rocker arm for the intake valve 1, U is a rocker arm for the exhaust valve 2, and these rocker arms 23.24
1 is arranged above and parallel to the camshaft 20.
It is rotatably attached adjacent to the book rocker shaft 25. Here, these rocker arm levers 24 are attached to the rocker shaft 25 so as to be movable in the axial direction, and are provided between the rocker bracket 26 and the switching ring 28 that is fitted in the electromagnetic actuator 27 and moves on the rocker shaft 25. The cams 21a, 22a for operation or the cam 21b for rest are positioned via springs 29, 30 and are controlled to move in the axial direction by the movement of the switching ring 28 (8).

22b.

Next, to explain the operation, switching from operation to rest is performed by moving the switching ring 28 in the direction A by the electromagnetic actuator 27, but during the exhaust stroke or the intake stroke that follows, the intake valve 1 side is At least one cam 218° 22a on the exhaust valve 2 side is connected to the rocker arm 2.
3.24 and is driving the valve spring 13.24, the load of the valve spring 13.14 is applied and the frictional force is extremely large. It just happens. When the suction stroke is finished and the lift of both valves 1 and 2 is O,
Cam 21a.

22a and the rocker arm 23.24 and the load of the valve spring 13.14 no longer acts, so the compressed spring 30
The rocker arms 23 and 24 move integrally and simultaneously in the A direction due to the acting force of
The switching is completed when the rocker arms 23 and 24 come to face each other.

On the contrary, when switching from rest to operation, after the switching ring 28 is moved in the direction B by the electromagnetic actuator 27, the cams 21b, 22b and the rocker arm 23.2
When a clearance is created in the contact surface with the rocker arm 2, the action force of the compressed spring 29 causes the rocker arm 2 to
3.24 move integrally and simultaneously in the B direction, and as a result, the operating cams 21a + 22a and the rocker arm 2
3.24 is opposite.

If the rocker arms 24 for the intake valve 1 and the exhaust valve 2 are moved integrally and simultaneously on one rocker shaft δ in this way, the control system from the electromagnetic actuator 27, that is, the switching ring 4 and the spring 29.30
Not only can they be shared, but they are always switched at the same time, improving reliability and durability.

In addition, in such a valve operation switching device, it is necessary to maintain an appropriate pulp clearance in order to smooth the switching operation and the like. In this case, as shown in FIG. 9, a shim 31 is inserted between the head of the intake valve 1 (the same applies to the exhaust valve 2) and the rocker arm 23, and the shim 3 of an appropriate thickness is inserted.
The valve clearance can be adjusted by selecting and replacing the rocker arm 23 as appropriate.Furthermore, the rocker arm 23 can be brought into contact with the shim 31 via an adjustment bolt 32 attached to its tip. west,
The valve clearance may be adjusted by rotating the adjustment bolt 32.

33 is a spring retainer, 34 is a bolt, and 35 is a lock nut for the adjustment bolt 32.

As explained above, according to the present invention, each rocker arm of the intake valve and exhaust valve of the cylinder whose operation and deactivation are to be switched when controlling the number of cylinders is supported by a single rocker shaft, and integrated in the axial direction by an actuator. Since both targets are moved at the same time, it is possible to switch completely with a single switching mechanism, reducing the number of parts and manufacturing costs. It is guaranteed that the cylinder number control device will be used, and the reliability and durability of the cylinder number control device will be improved.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the valve actuation applied to the intake and exhaust valves of the cylinders that are switched between operation and deactivation in order to effectively control the number of cylinders, and Figure 2 is the characteristic of the valve lift shown above. 3 is a characteristic diagram of the change in cylinder pressure of each cylinder during cylinder number control obtained when the same characteristics as above are given, FIG. 4 is a plan view showing a conventional example of a valve operation switching device, and FIG. The figure is an enlarged view of the main part of FIG. 4, FIG. 6 is a VT-Vl sectional view of FIG. 5, FIG. 7 is a plan view of a valve operation switching device showing an embodiment of the present invention, and FIG. 7 is a cross-sectional view taken along the line ■--■, and FIG. 9 is a cross-sectional view showing an example of partial improvement. 1... Intake valve 2... Exhaust valve 20... Cam shirt) 21a, 22a... Cam for operation
21b, 22b...Cam for rest 23.24...
・Rocker arm 25...Rocker shaft 26
... Rocker bracket 27 ... Electromagnetic actuator 28 ... Switching ring 29, 30 ... Spring patent applicant Agent of Nissan Motor Co., Ltd.
Patent attorney Fujio Sasashima (e-) (joint)

Claims (1)

[Claims] In a multi-cylinder internal combustion engine, the rocker arms for driving the intake valves and exhaust valves of some cylinders whose combustion is paused depending on the engine operating conditions are moved in the axial direction of the rocker shaft by actuators that operate according to the conditions. An internal combustion engine in which valve operation of an intake valve and an exhaust valve of a relevant cylinder is switched by selectively engaging one of a pair of cams with different profiles arranged in parallel in the axial direction of a camshaft. In the valve operation switching device, the rocker arms for driving the intake valves and exhaust valves of the some cylinders are supported by one rocker shaft, and are moved integrally and simultaneously in the axial direction by an actuator. Valve operation switching device for internal combustion engines.