JPS61247805A - Tappet device of internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve combustibility by stopping operation of intake and exhaust valves under small load for making partial-cylinder operation, and narrowing opening degree of operating valves. CONSTITUTION:A longitudinal hole 8 of a bridge 2 is fit with free sliding movement around a bridge guide shaft 4 planted in a cylinder head 6. A piston 11 with longitudinal grooves (b) (c) is fit with free sliding movement in a wider- diameter longitudinal hole 10 continuing from the longitudinal hole 8. A base panel 12 is installed at the lower part of the piston 11 inside the longitudinal hole 8 to form an oil chamber 13 between the base panel 12 and the piston 11. An oil duct (A) inside the cylinder heat 6 is connected to an oil duct (C) inside the bridge guide shaft 4 and an oil duct (G) inside the bridge 2, and an oil port 26 is substantially closed by the piston 11. The piston 11 is rotated by a control lever 20 through gears 11' and 23. Under small load, the lever 20 is moved to control the piston 11 so that the longitudinal groove (b) or (c) meets the oil port 26, thus the opening degree of intake and discharge valves can be narrowed.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a valve train for an internal combustion engine.

(Prior technology) In direct injection combustion type cylinder diesel engines, during no-load idling operation, a small amount of fuel equivalent to the friction loss (frictional horsepower) of the engine is injected into the cylinder and combusted, but the combustion temperature is also low. Also, combustion is deteriorated due to depletion of fuel from the cylinder wall. In other words, blue-white smoke and a pungent odor are generated, causing problems. Therefore, in a multi-cylinder engine, for example, in a 6-cylinder engine, if fuel injection is cut in 3 or 4 of the 6 cylinders and only the remaining 3 or 2 cylinders are used for combustion, the amount of fuel injected per cylinder can be doubled or tripled. The combustion temperature also increases, and the above-mentioned problems are alleviated and improved. However, in a fuel-cut cylinder, the four steps of sucking air into the cylinder, compressing it, expanding it, and discharging it are repeated using only air, but there is suction resistance at the intake valve seat and discharge resistance at the exhaust valve seat. (throttling loss), extra loss work has to be done than when all cylinders are burnt, and that much more fuel is consumed.

However, if the intake and exhaust valves of the fuel cut cylinder are kept closed, the piston can compress the air and expand as it is, and theoretically there is no loss. However, in reality, the sliding part (
There is leakage from piston rings, etc.) and heat flow to the combustion chamber walls, both of which result in losses, but the losses are smaller than when the intake and exhaust valves are operated.

Further, in a general multi-cylinder engine, the valve rla closed wJ11 is fixed and there is no mechanism for stopping the operation of any valve, so the above-mentioned problems are unavoidable.

(Objective of the Invention) (1) To obtain good combustion by changing the opening/closing angle (period) of the intake and exhaust valves during no-load idling and low-load operation.

(2) During the same operation, by stopping the fuel injection and operation of the intake and exhaust valves and operating only a small number of cylinders (for example, 2 to 3 cylinders out of 6 cylinders), uniform fuel injection and a rise in temperature within the cylinders result in better combustion. get.

(3) Add operation (1) to (2) above to improve performance.

(Structure of the Invention) The present invention provides a piston in which a vertical hole of a valve actuating bridge is slidably fitted into a bridge guide shaft installed in a cylinder head, and a vertical groove opening downward on the side surface is provided at the upper end of the vertical hole. A bottom plate is provided below the piston in the vertical hole, an oil chamber is formed between the bottom plate and the piston, and a pressurized oil passage leading to the bridge is opened on the inner surface of the vertical hole. This is a valve operating device for an internal combustion engine that is provided with a piston rotation mechanism and that changes the amount of hydraulic pressure trapped in a vertical hole by rotating the piston and communicating the opening of a pressurized oil passage with a vertical groove.

(Example) In Fig. 1, 1 is a valve arm, 2 is a bridge for valve operation, 3 is a valve, 4
5 is a bridge guide shaft, 5 is a spring, and 6 is a cylinder head. A bridge guide shaft 4 is implanted in the cylinder head 6, and a vertical hole 8 of the bridge guide 2 is slidably fitted onto this shaft 4. The vertical hole 8 is continuous with a large-diameter vertical hole 10 via a step 9, and a dowel piston 11 is slidably fitted into the large-diameter vertical hole 10 and is fitted into the step 9 in a fluid-tight manner. Spring support bottom plate 1
An oil chamber 13 is formed between the piston 2 and the dowel piston 11. The oil chamber 13 also serves as a spring chamber for a piston return spring 14, and the piston 11 is urged upward by the spring 14 and comes into contact with the valve arm 1. 11' is a head gear provided integrally with the piston 11.

In Fig. 2 showing the ■-■ cross section of Fig. 1, the head gear 1
A gear 23 at the upper end of the rotating shaft 19 meshes with the gear 1', and the rotating shaft 19 is supported in a shaft guide 24 embedded in the cylinder head 6 so as to be freely rotatable in the U direction.
Connected to 0.

The oil passage A in the cylinder head 6 passes through the oil passage C in the bridge guide shaft 4 and the oil passage G in the bridge 2 to the oil hole 26°.
is substantially closed by the piston 11. An air hole 2 is provided in the piston 11 so as to communicate with the upper end of the oil chamber 13.
7 is substantially closed by the bridge 2. An air hole 28 between the bottom plate 12 and the bridge guide shaft 4 communicates with the atmosphere through an air hole 29.

As shown in FIGS. 4 and 5, the piston 11 has a vertical groove b (length j!1) that opens downward at the end surface a of the lower end, as shown in FIGS.
c (length j2) and are separated by an angle θ2. θ1 is the angle from the state shown in FIG. 2 to the vertical groove.

1 and 2 show the state when the valve is closed.

When the timing for opening the intake or exhaust valve is reached due to rotation of the camshaft, the valve arm 1 moves to push down the head gear 11- of the piston 11. In FIG. 2, when the piston 11 is pushed down slightly, the air hole 27 and oil hole 26 are closed, and the oil chamber 13 containing the spring 14 is in a sealed state.
The valve 3 is opened together with the bridge 2. When the valve 3 returns to the closed position 1ffl (Fig. 2) due to the rotation of the cam,
The piston 11 is pushed upward slightly by the spring 14, the oil hole 26 communicates with the oil chamber 13, and hydraulic pressure is supplied into the oil chamber 13 through oil passages A, C, and G. Since the vertical hole 10 into which the piston 11 is fitted is precisely finished, there is no leakage from the fitting part. Further, the vertical positions of the bridge upper end surface d, the air hole 27, and the lower end surface a of the piston 11 and the oil hole 26 are adjusted in advance.

As shown in FIGS. 4 and 5, the piston 11 has a cutout-shaped vertical groove c with a length of 11 and ρ2 on its outer circumference. By matching them, the stroke of the piston 11 in which the oil in the oil chamber 13 is confined changes. When the vertical groove and the oil hole 26 are aligned, the piston 11 has an idle stroke of 11, and as a result, the opening angle of the valve becomes the old n in FIG. Vertical hole C
When the oil hole 26 and the oil hole 26 are aligned, the oil hole 26 communicates with the oil chamber 13 throughout the valve stroke of the piston 11, and the valve 3 remains open. In that case, the piston 11 is returned to the position shown in FIG. 2 by the spring 14 in preparation for the next cycle, and oil is supplied from the oil passage A of the cylinder head 6.

Next, the operation in each operating state will be explained.

(1) During normal operation: The piston 11 is in the position shown in FIG.

(2) During low load operation: The rotation and load of the engine are detected, and the lever 20 is moved by an actuator (not shown) under preset conditions.
A gear 23 controls the piston 11 so that the vertical groove fits into the oil hole 26.

(3) During idling and no-load operation; cut off the fuel of the cylinder to be reduced, and then turn the lever 20
The piston 11 is rotated until the vertical groove C and the oil hole 26 are aligned. In that case, the performance improvement effect can be obtained by controlling the other cylinders as shown in (2) above.

(Effects of the Invention) According to the present invention, the operation of the intake and exhaust valves is stopped to reduce cylinder operation 1.
At the same time, the opening angle of the operating valve can be narrowed to further improve combustion performance.

In other words, the opening/closing timing and period (valve timing) of the intake valve and exhaust valve of a diesel engine are determined at the rated 0 rotation, under load, and the output.
Since the settings are made to maximize performance such as exhaust concentration and fuel efficiency, performance at low rotation, no-load, and low-load conditions is sacrificed. Under the above operating conditions, performance improvement can be seen by reducing the plane angles of both the intake and exhaust valves (dashed line in Figure 6). , FIG. 6 is a graph showing the relationship between valve lift and crank angle, and FIG. 7 is a timing diagram.

A performance improvement effect can be obtained by using the timing indicated by the broken line in FIG. In other words, 5O1EC...prevents intake air from blowing into the exhaust air (effective use of intake air) As explained above, according to the present invention, it is possible to lift and open the intake and exhaust valves without significantly changing the structure of the current operating valve device. Since the angle can be changed stepwise or steplessly, the operation can be stopped, and the timing of the intake and exhaust valves can be changed at the same time, there is an advantage that the combustion performance of the engine can be improved.

(Another Embodiment) Instead of providing a plurality of vertical grooves S and C having different lengths, a wide vertical groove with an inclined upper edge may be provided. Instead of compressing the return spring 14 in the oil chamber 13, a return spring (plate spring) for the piston 11 may be provided between the valve arm 1 and the piston 11.

[Brief explanation of drawings]

Claims (4)

[Claims] (1) The vertical hole of the valve operating bridge is slidably fitted into the bridge guide shaft installed in the cylinder head, and the piston, which has a vertical groove opening downward on the side surface, is slidably fitted to the upper end of the vertical hole. A bottom plate is provided below the piston in the vertical hole, an oil chamber is formed between the bottom plate and the piston, a pressurized oil passage leading to the bridge is opened on the inside of the vertical hole, and the piston rotation mechanism is formed. A valve train for an internal combustion engine in which the amount of hydraulic pressure trapped in a vertical hole can be varied by rotating a piston and communicating the opening of a pressurized oil passage with a vertical groove. (2) A valve train for an internal combustion engine according to claim 1, wherein the vertical groove is formed of a plurality of longitudinal grooves having different lengths. (3) The valve operating system for an internal combustion engine according to claim 1, wherein the oil chamber also serves as a spring chamber for a piston return spring. (4) The valve train for an internal combustion engine according to claim 1, wherein the pressurized oil passage in the bridge communicates with the oil passage in the cylinder head via the oil passage in the bridge guide.