JPH05133225A - Valve seat cooling construction - Google Patents

Abstract

PURPOSE:To strongly cool a valve seat by aiming at only the valve seat so as to enhance cooling character of intake and exhaust valves. CONSTITUTION:A tubular port liner 20 is fitted along the internal wall of an exhaust port hole 19 that communicates with a combustion chamber 2 in a cylinder heat 1. A valve seat 7 is provided by performing cladding on the end surface 20a of an opening positioned on the side of the combustion chamber 2 of the port liner 20. A cooling liquid passage 21 is formed inside the wall thickness of the port liner 20. Further, heat insulating materials 22, 23 are provided between the port liner 20 and the internal wall of the exhaust port hole 19, and on the internal wall of the tubular hole of the port liner 20 respectively. With these means, heat input from the side of the cylinder heat 1 and from the exhaust gas that passes the tubular hole of the port liner 20 (an exhaust port 4) is shut off, to the cooling liquid passage 21 and its cooling liquid is used for cooling of only the valve seat 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve seat, that is, a valve seat, which is mounted on an opening of an intake / exhaust port communicating with a combustion chamber in a cylinder head of an engine, and more particularly to a cooling structure thereof.

[0002]

2. Description of the Related Art Conventionally, as the compression ratio is increased for the purpose of improving the performance of the engine, the temperature inside the combustion chamber becomes high and knocking easily occurs. In the combustion chamber, the temperature of the intake / exhaust valve that is exposed to the high-temperature combustion gas during combustion is relatively high, and the temperature of the exhaust valve that is exposed to already burned gas during exhaust is the highest. Therefore, lowering the temperature of these intake and exhaust valves is required to prevent knocking. Therefore, in order to lower the temperature of the intake and exhaust valves,
Techniques have been proposed that take into consideration the cooling performance of the valve seat, which also serves as an escape port for heat from the valve.

For example, in the technique disclosed in Japanese Utility Model Laid-Open No. 60-122528, in order to cool the valve seat, it is disclosed to form a cooling liquid passage for circulating a cooling liquid around the seat. ..

[0004]

However, in the above-mentioned prior art, in addition to the heat input from the valve seat, there is heat input from the intake / exhaust port and the cylinder head in the coolant passage. Therefore, in the configuration of the conventional technique, it is not possible to cool the valve seat strongly by aiming at the valve seat alone, and the cooling of the intake / exhaust valve is insufficient.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to improve the cooling performance of an intake / exhaust valve, and in particular, a seat that can be strongly cooled by aiming at the valve seat alone. It is to provide a valve cooling structure.

[0006]

In order to achieve the above object, the present invention provides a cooling structure for a valve seat mounted in an opening of an intake / exhaust port communicating with a combustion chamber in a cylinder head of an engine. The cylindrical port liner is fitted along the inner wall of the intake / exhaust port hole, and the valve seat is connected to the opening end surface of the port liner located on the combustion chamber side. A cooling liquid passage for circulating a cooling liquid that extends along the longitudinal direction of the intake / exhaust port hole is formed inside, and further between the port liner and the inner wall of the intake / exhaust port hole, and on the inner wall of the cylinder hole of the port liner. Each has its own insulation.

[0007]

According to the above construction, the valve seat is cooled through the opening end face of the port liner by flowing the cooling liquid into the cooling liquid passage of the port liner. Moreover, the cooling fluid passage extends along the longitudinal direction of the inner wall of the intake / exhaust port hole, and the heat insulating material is provided between the port liner and the inner wall of the intake / exhaust port hole, and on the inner wall of the cylindrical hole of the port liner. It is provided. Therefore, the heat input from the cylinder head side and the heat input from the exhaust gas passing through the cylindrical hole of the port liner are blocked in the coolant passage, and the coolant is used only for cooling the valve seat.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the valve seat cooling structure of the present invention will be described in detail below with reference to FIGS.

FIG. 1 is a sectional view for explaining a valve operating system of one cylinder in the four-cylinder gasoline engine of this embodiment. An intake port 3 and an exhaust port 4 communicating with the combustion chamber 2 are provided in a cylinder head 1 that constitutes the engine. The intake port 3 is a passage for guiding the air-fuel mixture supplied from the upstream side to the combustion chamber 2. An intake valve seat 5 is press-fitted into the opening 3a of the intake port 3 that opens into the combustion chamber 2. And intake port 3
The intake valve 6 that opens and closes the intake valve seat 5
It is mounted so that it can be seated on. On the other hand, exhaust port 4
Is a passage for leading the burnt gas burned in the combustion chamber 2 to the outside. An exhaust side valve seat 7 is attached to an opening 4a of the exhaust port 4 which opens to the combustion chamber 2. The exhaust valve 8 that opens and closes the exhaust port 4 is
It is assembled to the exhaust side valve seat 7 so that it can be seated.

In this embodiment, the engine is a twin cam type, and each cylinder has a 4-valve intake / exhaust system. Two intake ports 3 and two exhaust ports 4 are provided for each cylinder, and two intake valves 6 and two exhaust valves 8 are provided accordingly. Here, one of the intake port 3 and the exhaust port 4 is illustrated and described.

The intake valve 6 and the exhaust valve 8 are respectively provided with stems 6a and 8a extending upward. The cylinder head 1 is formed with guide holes 9 and 10 through which the stems 6a and 8a pass. Then, in the guide holes 9 and 10, the stems 6a and 8a are connected to the stem guides 11,
It is supported via 12 so as to be vertically movable. Each stem 6
Valve springs 13 and 14, valve lifters 15 and 16 and the like are attached to the upper portions of a and 8a, respectively. A cam 17a is provided so as to engage with the valve lifter 15 corresponding to the intake valve 6. This cam 17
Reference numeral a denotes a plurality (eight in total for four cylinders) formed on the intake-side camshaft 17 supported by the cylinder head 1. On the other hand, a valve lifter 16 corresponding to the exhaust valve 8
Also, the cam 18a is also provided so as to be engaged. A plurality of cams 18a are provided on the exhaust side camshaft 18 supported by the cylinder head 1 (eight in total for four cylinders).
It was formed. The intake valve 6 and the exhaust valve 8 are urged upward by the urging forces of the valve springs 13 and 14 and in the directions in which they are seated on the valve seats 5 and 7 and close the intake port 3 and the exhaust port 4, respectively. .. In this biased state, the upper ends of the stems 6a and 8a are connected to the cams 17a and 18a via the valve lifters 15 and 16, respectively.
Always connected to.

A timing pulley (not shown) is provided at one end of each of the intake side camshaft 17 and the exhaust side camshaft 18. These timing pulleys are drivingly connected to the crankshaft via a timing belt (not shown).

Therefore, when the engine is in operation, power is transmitted from the crankshaft to each timing pulley via the timing belt, so that each camshaft 17,
18 is rotated, and each cam 17a, 18a is rotated. Further, the valve lifters 15 and 16 are pressed against the biasing forces of the valve springs 13 and 14 in accordance with the profiles of the rotated cams 17a and 18a,
The intake valve 6 and the exhaust valve 8 move downward, and the intake port 3 and the exhaust port 4 are opened. Then, when the intake port 3 is opened by the intake valve 6, the air-fuel mixture is sucked into the combustion chamber 2. Further, when the exhaust port 4 is opened by the exhaust valve 8, the burned gas is discharged from the combustion chamber 2 to the exhaust port 4.

Next, the cooling structure of the exhaust side valve seat 7 will be described. The cylinder head 1 has an exhaust port 4
The exhaust port hole 19 corresponding to is formed. The exhaust port hole 19 is provided with a cylindrical port liner 20 fitted along the inner wall thereof. That is,
In this embodiment, the cylinder port side of the port liner 20 is the exhaust port 4. Further, the exhaust side valve seat 7 is provided on the opening end face 20a of the port liner 20 located on the combustion chamber 2 side.
Are connected and provided. In this embodiment, the port liner 20 is encased at the same time as the cylinder head 1 is cast. Further, the exhaust side valve seat 7 is provided by being built up in advance on the opening end face 20a. .

FIG. 2 is an enlarged sectional view showing the port liner 20 and the like, and FIG. 3 is a sectional view taken along the line AA of FIG. As shown in FIGS. 1, 2 and 3, a cooling liquid passage 21 extending along the longitudinal direction of the exhaust port hole 19 is formed inside the wall thickness of the port liner 20. Engine cooling water is circulated in the cooling liquid passage 21 as cooling liquid. A heat insulating material 22 made of a ceramic material is interposed between the outer peripheral surface of the port liner 20 and the inner wall of the exhaust port hole 19. The heat insulating material 22 extends and is interposed between the outer peripheral surface of the exhaust side valve seat 7 and the exhaust port hole 19. Further, a heat insulating material 23 made of a ceramic material is attached to the inner wall of the cylinder hole of the port liner 20. That is, in this embodiment, a cooling liquid passage 21 independent of the cylinder head 1 is provided in addition to the water jacket 24 for circulating cooling water formed in the cylinder head 1. The cooling liquid passage 21 is provided so as to be thermally independent of the cylinder head 1 by the heat insulating materials 22 and 23. Further, the port liner 20 is formed with a guide hole 25 which is aligned with the guide hole 10 of the cylinder head 1, so that the stem guide 12 and the stem 8a can be penetrated.

In this embodiment, the port liner 20 is formed integrally with the port liners of the other adjacent cylinders so as to be continuous in the lateral direction. The cooling liquid passage 21 of the port liner 20 is also formed so as to communicate with the cooling liquid passages of the other adjacent port liners.

Next, the operation of the valve seat cooling structure configured as described above will be described. Now, when the cooling water is flown through the cooling liquid passage 21 of the port liner 20, the exhaust side valve seat 7 is cooled by the cooling water taking heat from the opening end face 20a of the port liner 20. Moreover, the coolant passage 21 extends along the longitudinal direction of the inner wall of the exhaust port hole 19, and the port liner 20 and the exhaust port hole 1 are provided.
Heat insulating materials 22 and 23 are provided between the inner wall of the inner wall 9 and the inner wall of the port liner 20. Therefore, heat input from the cylinder head 1 side is blocked by the heat insulating materials 22 and 23 in the cooling liquid passage 21. Further, in the cooling liquid passage 21, heat input from the exhaust gas passing through the cylindrical hole of the port liner 20, that is, the exhaust port 4, is used as the heat insulating materials 22 and 2.
Blocked by 3.

Therefore, the cooling water in the cooling liquid passage 21 is used only for cooling the exhaust side valve seat 7. As a result, it is possible to strongly cool the exhaust side valve seat 7 independently, and improve the cooling performance of the exhaust side valve seat 7.

Since the exhaust side valve seat 7 can be strongly cooled as described above, the exhaust valve 8 seated on the valve seat 7 can be efficiently cooled. As a result, the exhaust valve 8 having a temperature relatively higher than that of the intake valve 6 is cooled, the temperature difference from the intake valve 6 is eliminated, and the temperature balance in the combustion chamber 2 is made uniform. As a result, the combustion in the combustion chamber 2 can be made uniform, and thus knocking can be effectively prevented.

The present invention is not limited to the above-described embodiment, but may be implemented as follows with a part of the configuration appropriately modified without departing from the spirit of the invention. (1) In the above embodiment, the exhaust side valve seat 7 is cooled, but the intake side valve seat 5 may be cooled.

(2) In the above embodiment, the cooling water is made to flow through the cooling liquid passage 21, but other cooling liquids may be made to flow therethrough. (3) In the above-described embodiment, the exhaust side valve seat 7 is built up on the opening end surface 20a of the port liner 20 in advance. However, a recess is formed in the opening end surface 20a of the port liner 20, and the valve is formed in the recess. It is also possible to press fit the sheet.

[0022]

As described above in detail, according to the present invention, the cylindrical port liner is fitted along the inner wall of the intake / exhaust port hole, and the valve is provided at the opening end face of the port liner located on the combustion chamber side. A sheet is connected to form a cooling liquid passage inside the wall thickness of the port liner, and further, a heat insulating material is provided between the port liner and the inner wall of the intake / exhaust port hole and on the inner wall of the cylinder hole of the port liner. Since it is provided, heat input from the cylinder head side and exhaust gas passing through the cylinder hole of the port liner is blocked in the cooling liquid passage, and it is possible to strongly cool especially the valve seat individually, so the intake and exhaust valves It has an excellent effect that the cooling property of can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a cylinder head illustrating a valve train of a gasoline engine according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a port liner and the like in one embodiment.

FIG. 3 is a sectional view taken along line AA of FIG. 2 in one embodiment.

[Explanation of symbols]

1 ... Cylinder head, 2 ... Combustion chamber, 3 ... Intake port, 4
... Exhaust port, 5 ... Intake side valve seat, 6 ... Exhaust side valve seat, 19 ... Exhaust port hole, 20 ... Port liner, 20a ... Open end face, 21 ... Coolant passage, 22, 23
… Insulation.

Claims (1)

[Claims] 1. A cooling structure for a valve seat mounted on an opening of an intake / exhaust port communicating with a combustion chamber in a cylinder head of an engine, the cylindrical port liner extending along an inner wall of the intake / exhaust port hole. And the valve seat is connected to the opening end surface of the port liner located on the combustion chamber side, and is provided inside the wall thickness of the port liner along the longitudinal direction of the intake and exhaust port holes. A cooling liquid passage for extending the cooling liquid is formed, and a heat insulating material is further provided between the port liner and the inner wall of the intake / exhaust port hole, and on the inner wall of the cylindrical hole of the port liner, respectively. Valve seat cooling structure to be used.