JPS6218648Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a cooling device for an exhaust valve of an internal combustion engine.

In recent years, the output per single cylinder of internal combustion engines has increased, and at the same time the heat load on the combustion chamber within the engine cylinder has increased.In particular, the exhaust valve, which constantly comes into contact with high-temperature exhaust gas during operation, is subject to increased heat load and wear. , gas leakage, burnout, etc. are promoted, resulting in a significant decrease in durability. Therefore, it is necessary to cool the exhaust valve to lower its temperature, and to improve the lubrication between the stem and valve guide cylinder of the exhaust valve to reduce sliding wear and improve the durability of the exhaust valve.

Conventionally, a method has been used in which a cooling fluid passage is provided inside the exhaust valve body and the cooling fluid is circulated from the outside, but it is difficult to process the cooling passage inside the exhaust valve, and the cooling fluid is The drawback was that the circulation system was complicated. In addition, forced lubrication between the exhaust valve stem and the valve guide tube may cause the lubricating oil to become contaminated due to exhaust gas blowing up from the gap between the stem and the valve guide tube, or vice versa. The problem was that it flowed down the stem and fouled the exhaust valve.

This idea was made to eliminate the above-mentioned drawbacks, and allows cooling air to flow along the outer circumferential surface of the exhaust valve stem, effectively cooling the exhaust valve and making it possible to forcefully lubricate the stem. It is an object of the present invention to provide an exhaust valve cooling device which has a simple structure and is easy to implement. An embodiment of this invention will be described below based on the drawings.

In the drawings, 1 indicates a cylinder head of an internal combustion engine, and 2 is a valve guide cylinder that is fitted into the cylinder head 1 and whose lower end faces the inside of an exhaust port G provided in the cylinder head 1. Hole 2
A stem 3a of an exhaust valve 3 that opens and closes the exhaust port G is inserted into a. Two upper and lower annular grooves 6 and 4 are provided on the lower outer periphery of the valve guide cylinder 2, forming an annular passage between the groove and the inner wall 1a of the cylinder head 1. A plurality of oil supply holes 7 and air holes 5 are provided around the valve guide cylinder 2, each penetrating from the bottoms of the upper and lower annular grooves 6, 4 to the valve hole 2a. On the other hand, a cooling air passage 8 is provided penetrating from the outer surface of the side wall 1b of the cylinder head 1 toward the lower annular groove 4 (annular groove on the valve head side) on the outer periphery of the valve guide tube 2. A lubricating oil passage 9 is provided penetrating toward the upper annular groove 6 from the outer surface of the side wall 1b. The cooling air passage 8 is
It is connected to an air line 11 via a terminal 10 screwed into its outer opening, which air line 11 is further connected to the intake pipe of the internal combustion engine or other cooling air supply source (not shown). It is connected to the cooling air pipe 12 via a pipe joint 13.

The lubricating oil passage 9 is connected to a lubricating oil branch pipe 16 via a terminal 10 screwed into its outer opening, and this lubricating oil branch pipe 16 is further connected to the internal combustion engine via a check valve 17. It is connected to the lubricating oil pipe 8.

The stem 3a of the exhaust valve 3 has a lower portion extending from the axial position facing the air vent 5 provided in the valve guide tube 2 to the umbrella portion 3b when the exhaust valve 3 is closed.
An annular gap 1 between the valve hole 2a of the valve guide cylinder 2 and the annular gap 1 for communicating cooling air between the air vent hole 5 and the exhaust port G, which is formed as a step-slimmed small diameter portion.
4 is formed, and a portion above the small diameter portion is formed as a large diameter portion that is slidably fitted in the valve hole 2a in the axial direction, and when the exhaust valve 3 is opened, the air vent hole 2a is formed. The opening of the valve hole 5 is closed, and communication between the air vent 5 and the exhaust port G is cut off.

In the device configured as described above, during operation of the internal combustion engine, the cooling air introduced into the cooling air pipe 12 reaches the air pipe 11, the terminal 10, the cooling air passage 8, and the annular groove 4, and the exhaust valve 3 is closed. Sometimes it blows out from the gap 14 through the air vent 5 and flows into the stem 3.
It flows along the outer periphery of the small diameter part of a, and the umbrella part 3 of the exhaust valve 3
It is reversed on the upper surface of b and is discharged to the outside from the exhaust port G. When the compressed air leaves the gap 14, it expands adiabatically and the temperature of the air decreases, causing the stem 3a of the exhaust valve 3 to
, the outer circumferential surface of the exhaust valve 3 is effectively cooled.

Furthermore, at this time, since the cooling air passage 8 is opened toward the valve head portion 3b as described above, the exhaust valve 3
The pressure of the air leaking upward through the fitting gap between the large diameter part of the stem 3a and the valve hole 2a is applied to the lubricating oil pipe 1.
The pressure becomes lower than the pressure of the lubricating oil flowing through the lubricating oil passage 9, and the lubricating oil is supplied to the fitting gap between the large diameter part of the stem 3a of the exhaust valve 3 and the valve hole 2a, and the sliding parts thereof are Lubricated.

When the exhaust valve 3 is pushed down by a valve train (not shown), the large diameter portion of the stem 3a of the exhaust valve 3 closes the opening on the valve hole side of the air vent 5, so that cooling air is At the same time as the outflow is stopped, the backflow of exhaust gas from the exhaust port G to the cooling air passage 8 is prevented. On the other hand, at this time, more air leaks upward from the air vent 5 in the fitting gap between the stem 3a and the valve hole 2a, and the pressure of the leaked air increases to the lubricating oil pipe 18.
Since the pressure of the lubricating oil becomes higher than the lubricating oil pressure inside, the check valve 17 operates and stops lubricating the fitting gap between the stem 3a and the valve hole 2a, and the oil that has already been lubricated flows upward and leaks air. As a result, the fitting gap between the stem 3a and the valve hole 2a is sufficiently lubricated, and the lubricating oil is prevented from flowing down toward the umbrella portion 3b of the exhaust valve 3.

By bypassing the engine intake air that has passed through the air cooler from the turbocharger as the cooling air source for this invention, no special equipment is required, and during high loads that require sufficient cooling, the intake air Since the pressure is high, the amount of exhaust valve cooling air is also large, and at low loads when less cooling is required, the intake pressure is low.
The amount of cooling air is also automatically reduced to ensure efficient exhaust valve cooling.

As explained above, the exhaust valve cooling device of this invention has a cooling air supply source that penetrates the valve hole around the valve guide tube at a position below the lubricating point for the valve hole of the valve guide tube. A plurality of air vents are provided in communication with the exhaust valve, and the stem of the exhaust valve inserted into the valve hole is inserted into the exhaust valve from an axial position facing the air vent when the exhaust valve is closed. A lower portion reaching the umbrella portion of the valve hole is formed as a small diameter portion forming an annular gap for cooling air circulation communicating with the exhaust port between the valve hole and an upper portion of the valve hole. The large diameter portion is fitted into the hole so as to be slidable in the axial direction, and closes the valve hole side opening of the air vent when the exhaust valve is opened, thereby cutting off communication between the air vent and the exhaust port. Since the cooling air is jetted into the annular gap and cools the exhaust valve only when the exhaust valve is closed, the cooling medium does not flow inside the valve in order to cool the exhaust valve like in the past. There is no need to perform processing such as through holes, the structure is simple, and the exhaust valve can be easily cooled with air. In addition, when the cooling air exits the exhaust port from the annular gap between the small diameter part of the exhaust valve stem and the valve hole of the valve guide cylinder, it expands adiabatically and its temperature decreases, and this cooling air that has decreased in temperature directly , the outer peripheral surface of the exhaust valve can be effectively cooled.
Furthermore, since the entire circumference of the fitting gap between the exhaust valve stem and the valve hole of the valve guide cylinder is filled with cooling air to form an air seal, even if there is no sealing member in the fitting gap, the fitting gap can be closed. This eliminates the blowing up of exhaust gas, prevents deterioration of the lubricating oil at the sliding part between the stem and the valve hole, and eliminates the risk of the lubricating oil flowing down along the stem and contaminating the exhaust valve.
Forced lubrication of the stem portion becomes possible, improving the durability of the exhaust valve. Further, there are effects such as preventing corrosion of the stem portion due to exhaust gas and corrosion breakage of the valve spring.

[Brief explanation of the drawing]

The drawings show one embodiment of this invention, and FIG. 1 is a sectional view of the main part of an exhaust valve of an internal combustion engine cylinder head when the valve is closed, and FIG. 2 is a sectional view of the main part when the exhaust valve is open. 2...Valve guide tube, 2a...Valve hole, 3...Exhaust valve, 3a
... Stem, 3b... Umbrella part, 5... Air vent, 7... Oil supply hole, 8... Cooling air passage, 14... Gap.

Claims (1)

[Scope of utility model registration request] The valve guide tube 2, which is attached to the cylinder head 1 and whose lower end faces the exhaust port G of the cylinder head 1, is placed around the valve guide tube 2 at a position below the lubricating point for the valve hole 2a of the valve guide tube. Hole 2
A stem 3a of an exhaust valve 3 is provided with a plurality of air vents 5 that penetrate through the air hole 2a and communicate with a cooling air supply source, and is inserted into the valve hole 2a to open and close the exhaust port G. When the exhaust valve 3 is closed, a lower portion of the exhaust valve 3 from the axial position facing the air vent 5 to the umbrella portion 3b is located between the exhaust port G and the valve hole 2a. It is formed as a small diameter part that forms an annular gap 14 for cooling air circulation communicating with the cooling air, and the part above the small diameter part is
It is fitted into the valve hole 2a so as to be slidable in the axial direction, and when the exhaust valve 3 is opened, the valve hole side opening of the air vent 5 is closed, and the air vent 5 and the exhaust port G are connected to each other. An exhaust valve cooling device for an internal combustion engine, characterized in that the exhaust valve cooling device is formed as a large diameter portion that cuts off communication.