JPH02130206A - Cooling device for exhaust valve - Google Patents

Abstract

PURPOSE:To make it possible to restrain the temperatures of the neck and head parts of an exhaust valve from increasing, by cooling the exhaust valve in such a way that the neck part of the exhaust valve in a seated condition is made into contact with a curved surface part of an inner guide. CONSTITUTION:When the head part 4a of an exhaust valve 4 is seated on a valve seat 3 by a drive device 10 upon completion of an exhaust stroke of an internal combustion engine, a curved surface part 7a of an inner guide 7 driven by the drive device 4 in a direction remote from the exhaust valve 4 (that is, the direction toward the head part 4a) abuts against the neck part 4b of the exhaust valve 4. With this arrangement, heat is absorbed from the neck part 4b whose temperature has been raised, by the curved surface part 7a making contact with neck part 4a. Further, the part around the center of the head part 4a is indirectly cooled due to the heat absorption from the neck part 4b. Such cooling can be made every one of intake, compression and combustion strokes, and accordingly, the exhaust valve 4 is driven by the drive device 10 in the direction in which the exhaust valve 4 is parted from the valve seat 3 upon initiation of an exhaust stroke, and further, the inner guide 7 is taken into upward from an exhaust port 2, thereby it is possible to prevent the exhaust efficiency from degrading.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cooling device for an exhaust valve used in various internal combustion engines such as automobile engines.

[Conventional technology]

As exhaust valves for automobile engines, mushroom-shaped exhaust valves with generally umbrella-shaped heads are widely used. Third
As shown in the figure, this exhaust valve 30 is connected to a cylinder head 3.
Although the head 30a and the neck 30b following the head 30a are exposed to high temperature exhaust gas, the temperature rises rapidly. and head 3
Heat is removed from the vicinity of the seating surface 33 of the valve seat 34 when the valve seat 34 is seated, so the central part of the lower surface of the head 30a and the neck 30b exhibit the highest temperature, but conventionally there is no way to cool these parts. , which hinders the improvement of engine performance. Further, the guide 32 is made elongated as shown by the chain line 35 in FIG.
0b and the head 30a indirectly, but since they are far from the neck 30b and the head 30a, a large amount of heat removal cannot be expected; rather, the guide 32 protrudes largely into the exhaust gas passage, thereby reducing the amount of exhaust gas. It has the disadvantage of causing a decrease in efficiency.

[Problem to be solved by the invention]

This invention was made in view of the above points, and it is possible to suppress the temperature rise in the neck and head of the exhaust valve, and
It is an object of the present invention to provide an exhaust valve cooling device that does not cause a decrease in exhaust efficiency.

[Means to solve the problem]

However, the exhaust valve cooling device of the present invention includes a mushroom-shaped exhaust valve whose head touches and separates from a valve seat of an exhaust port provided in a cylinder head, and a curved surface portion shaped to follow the neck of the exhaust valve at the tip. an inner guide slidably fitted onto the shaft of the exhaust valve; an outer guide fixed to the cylinder head and slidably guiding the inner guide; and a drive H position that reciprocates, and the curved surface portion of the inner guide driven by the drive device abuts the neck portion of the exhaust valve with the head seated on the valve seat. It is characterized by being configured as follows.

[Effect]

In the exhaust valve cooling device of the present invention, when the head of the exhaust valve is seated on the valve seat by the drive device at the end of the exhaust stroke of the internal combustion engine, the drive device moves the exhaust valve in the opposite direction (direction toward the head of the exhaust valve). ) The curved surface of the inner guide that is driven by the exhaust valve comes into contact with the neck of the exhaust valve, and the heated neck absorbs heat and is cooled by the contacting curved surface. In addition, the vicinity of the center of the lower surface of the head of the exhaust valve is also indirectly cooled by heat removal from the neck. The above cooling is performed during each of the intake, compression, and explosion strokes of the internal combustion engine. At the start of the exhaust stroke, the exhaust valve is driven away from the valve seat by the drive device, and the inner guide is pulled upward from the exhaust gas passage. Since the exhaust gas does not protrude significantly into the exhaust gas passage, deterioration in exhaust efficiency is prevented.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG.

In the figure, 1 is the cylinder head of the engine, 2 is its exhaust port, and 3 is the valve seat.The seating surface 5 of the head 4a of the mushroom-shaped exhaust valve 4 comes into contact with and separates from the valve seat 3. It has become. 6 is a cylindrical outer guide fixed to the cylinder head 1, and 7 is an inner guide slidably guided by the outer guide 6.

This inner guide 7 is cylindrical and has an exhaust valve 4 at its tip.
Shape along the neck 4b (same shape as the curved surface of the neck 4b)
It has a curved surface portion 7a. Note that this inner guide 7
is preferably made of a metal with as high a thermal conductivity as possible, such as cast iron. The shaft portion 4C of the exhaust valve 4 is slidably fitted into the inner diameter portion of the inner guide 7.

On the other hand, reference numeral 10 denotes an electromagnetic driving device that reciprocates the exhaust valve 4 and the inner guide 7 in opposite directions.
A disc-shaped σ actuating piece 11 made of ferromagnetic material is fixed to the upper end of C.
and a guide drive section 14 that drives an annular actuating piece 13 made of ferromagnetic material fixed to the upper end of the inner guide 7. The guide drive unit 14 includes an upward coil 1 in a yoke 15 attached to the cylinder head 1.
6a and a bobbin 17 wound with a downward coil 16b. The valve drive unit 12 also includes a bobbin 21 in which an upward coil 20a and a downward coil 20b are wound, in a joint filQ fitted into a housing 18 attached to the cylinder head 1.

22 is a spacer. Reference numerals 23 and 24 designate coil drive circuits so that the upward coil 20a of the valve drive section 12 and the downward coil 16b of the guide drive section 14 are simultaneously excited, and similarly the downward coil of the valve drive section 12. 20b and the upward coil 16a of the guide drive section 14 are excited at the same time, an excitation current is generated, and the timing of the excitation is controlled by the engine control device 25, which has a built-in computer. It is now controlled by IJ.

In the device configured as described above, at the end of the exhaust stroke of the engine, the upward coil 20a is energized by the coil drive circuit 23, and at the same time, the downward coil 16b is energized by the coil drive circuit 24, as shown in FIG. Actuating piece 11
is attracted by the upward coil 20a, the exhaust valve 4 is pulled up, and the head 4a is seated on the valve seat 3. At the same time, the actuating piece 13 is attracted by the downward coil 16b, and the inner guide 7 is pulled down. The curved surface portion 7a is the neck portion 4 of the exhaust valve 4.
b. This state is maintained during the intake, compression, and explosion strokes of the engine, and as a result, the neck 4b of the exhaust valve 4, which has been heated by the exhaust gas and whose temperature has risen, is cooled by the heat removed by the curved surface 7a in contact with it. The vicinity of the center of the lower surface of the head 4a, which is one high heating point, is also indirectly cooled and its temperature decreases.

In the exhaust stroke of the engine, the valve drive unit 1
The downward coil 20b of 2 and the upward coil 16a of the guide drive unit 14 are energized, and as shown in FIG. 2, the exhaust valve 4 is pulled down to open the exhaust port 2, and the inner guide 7 is pulled up. Since the exhaust gas is drawn upward from the exhaust gas passage, large resistance to the exhaust gas flow is prevented, and exhaust efficiency does not deteriorate. The neck portion 4b and head portion 4a of the exhaust valve 4, whose temperature has increased due to the passage of exhaust gas, are cooled by the inner guide 7 as described above after the exhaust stroke ends, and the same cycle is repeated thereafter to prevent the exhaust valve 4 from overheating. .

The present invention is not limited to the embodiment described above; for example, in the embodiment described above, an electromagnetic solenoid type was used as the drive device for driving the exhaust valve and the inner guide in opposite directions. A mechanical drive device such as the above may also be used. Furthermore, since the temperature of the exhaust valve is low when the engine rotates at low speeds, the engine speed may be detected by a rotation sensor provided in the crank part, etc., and the inner guide may be maintained in the pulled-up state when the number of rotations is below a predetermined number.

〔Effect of the invention〕

As explained above, according to the present invention, the curved surface portion of the inner guide is brought into contact with the neck portion of the exhaust valve in the seated state to cool it.
Since the inner guide can be retracted from the exhaust gas passage when the exhaust valve is open, it is possible to suppress the increase in humidity at the neck and head of the exhaust valve, and to create a useful exhaust valve cooling device that does not cause a decrease in exhaust efficiency. provided.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an exhaust valve showing an embodiment of the present invention;
FIG. 2 is a longitudinal sectional view of the exhaust valve in the open state, and FIG. 3 is a longitudinal sectional view showing an example of a conventional exhaust valve. 1... Cylinder head, 2... Exhaust port, 3...
・Valve seat, 4...exhaust valve, 4a...head, 4b...
Neck, 4c...shaft, 6...outer guide, 7...
Inner guide, 7a... Curved surface portion, 10... Drive device,
DESCRIPTION OF SYMBOLS 11... Operating valve, 12... Valve drive part, 13... Actuation piece, 14... Guide drive part, 16a... Upward coil, 16b... Downward coil, 20a. ... upward coil, 20b... downward coil, 23... coil drive circuit, 24... coil drive circuit. Figure 1

Claims (1)

[Claims] 1. A mushroom-shaped exhaust valve whose head touches and separates from the valve seat of an exhaust port provided in the cylinder head, and a curved surface portion shaped to follow the neck of the exhaust valve at the tip and slides onto the shaft of the exhaust valve. The exhaust valve includes an inner guide that fits freely, an outer guide that is fixed to the cylinder head and slidably guides the inner guide, and a drive device that reciprocates the exhaust valve and the inner guide in opposite directions. The exhaust valve is characterized in that the curved surface portion of the inner guide driven by the drive device comes into contact with the neck portion of the exhaust valve with the head seated on the valve seat. cooling system.