JP2509766Y2 - Thermostat device for engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a thermostat device provided in an engine cooling water passage.

<Prior Art> The engine cooling water is forcibly circulated between the engine body and the radiator by a water pump, and the circulation of this cooling water keeps the engine temperature proper and enables it to exert a sufficient function.

That is, when the engine temperature is lower than the proper temperature and the cooling water temperature is lower than a predetermined value, the thermostat senses this and closes the valve to shut off the cooling water main passage through the radiator. The cooling water is circulated and supplied to the engine body through a bypass passage that bypasses the engine.

Therefore, heat radiation of the cooling water by the radiator is stopped, and the temperature of the cooling water is increased. As the engine body warms up, the temperature of the cooling water rises, and when it reaches a certain temperature, the thermostat opens and opens the cooling water main passage that goes through the radiator. It is circulated and supplied to the engine body to maintain the engine body at an appropriate temperature.

As a thermostat device having the above-mentioned functions, there is a thermostat device as shown in FIG. 3 (Japanese Utility Model Publication No. 61-4).
1022, etc.).

That is, the main passage 1 of the engine cooling water passage from the cooling water outlet of the engine body to the radiator and the branch passage from the main passage 1 to bypass the radiator and the bypass passage 2 to the suction port of the water pump. , The thermostat 3 is interposed.

The thermostat 3 is fixedly supported on the wall portion of the thermostat housing H that constitutes a cooling water passage via the frames 4A and 4B. Then, a pellet 5 as a temperature-sensing portion is arranged in the central portion, and a wax that expands in volume at a predetermined temperature or higher is enclosed inside the pellet 5.
Further, a piston 6 having one end fixed to the upper frame 4A projects into the central portion of the pellet 5 so as to extend the stroke with respect to the pellet 5 due to the volume expansion of the wax. A valve 7 for opening and closing the main passage 1 is fitted and attached to the outer peripheral wall of the pellet 5. A spring 10 is interposed between the valve 7 and the lower frame 4B, and the valve 10 is always biased in the valve closing direction by the spring 10. The peripheral portion of the valve 7 is in pressure contact with the valve seat 11 formed on the upper frame 4A to close the main passage 1. Further, on the lower outer peripheral wall of the pellet 5 protruding from the lower frame 4B, a ring for restricting the downward movement of the opening / closing valve 13 for opening / closing the bypass passage 2 in the figure.
14 is fitted. The opening / closing valve 13 is provided so as to be slidable with respect to the pellet 5, and is always elastically biased toward the ring 14 by a spring 15.

The inlet portion of the bypass passage 2 is formed by a tubular portion 12 integrally formed with the thermostat housing H. An end surface of the tubular portion 12 on the main passage 1 side serves as a seating surface 8 of the opening / closing valve 13.

Here, when the wax enclosed in the pellet 5 expands in volume due to the temperature rise, the piston 6 is pushed out. This movement is transmitted to the valve 7 and pushes down the valve 7 to open the main passage 1. When the valve 7 has a predetermined opening or more, the opening / closing valve 13 on the bypass passage 2 side completely closes the bypass passage 2.

Therefore, when the water temperature becomes equal to or higher than the fully open temperature of the thermostat, the valve 7 overcomes the water pressure and the spring 10 and lifts, and the opening / closing valve 13 of the bypass passage 2 completely closes the bypass passage 2 so that the total amount of water flows to the radiator and is circulated and cooled. It

Then, as the cooling water temperature decreases, the valve 7 is returned to its original position by the spring 10.

Therefore, while the cooling water temperature is low, the cooling water does not flow through the radiator, enters the intake side of the water pump from the bypass passage 2, and circulates only inside the engine.

<Problems to be Solved by the Invention> However, in such a conventional thermostat device, on the inner wall surface of the tubular portion 12 formed in the thermostat housing H and the seating surface 8 of the opening / closing valve 13 of the tubular portion 12, Corrosion such as cavitation easily occurs.

That is, in the structure of the conventional bypass passage inlet portion, that is, the tubular portion 12, (a) the flow passage cross-sectional area is small.

(B) A curved flow path in which the flow line of the inflowing cooling water is not linear but has a certain angle.

(C) The flow passage cross-sectional area is narrowed immediately before the opening / closing valve 13 is closed and immediately after it is opened.

Due to the above reasons, the flow velocity of the cooling water is increased at the inlet portion of the bypass passage, and bubbles and swirls easily occur.

As a result, repeated impacts of the cooling water are applied to the inner wall surface of the cylindrical portion 12 and the seating surface 8, and corrosion such as cavitation easily occurs. Also, corrosion due to various chemicals contained in the cooling water is likely to occur.

In order to solve such a problem, the material of the entire thermostat housing H may be changed.

For example, the housing H, which was an aluminum casting, is changed to cast iron.

However, this causes a new problem that the weight of the housing is increased, and thus the weight of the engine is increased.

Therefore, in view of the conventional problems described above, the present invention aims to improve the corrosion resistance of the bypass passage inlet without increasing the weight of the engine.

<Means for solving the problem> A cooling water main passage connecting the engine body and the radiator,
In a thermostat device for an engine, which is interposed in a branch portion of a bypass passage extending directly from the engine body to the water pump without passing through the radiator, a part of the inner surface of the thermostat housing is projected inward and the thickness of the part is increased. A tubular portion formed by thickening the tubular portion, the opening of the tubular portion serving as the inlet portion of the bypass passage, and the entire tip surface of the tubular portion serving as the seating surface of the bypass passage opening / closing valve. A substantially cylindrical stainless insert covering the inner peripheral wall surface of the cylindrical portion and the seating surface of the bypass passage opening / closing valve consisting of the entire tip surface is press-fitted into the inner peripheral surface of the tubular portion of the thermostat housing or cast during molding of the thermostat housing. Therefore, it is installed.

<Operation> In such a configuration, since the bypass passage opening / closing valve seating surface consisting of the inner wall surface of the tubular portion of the thermostat housing and the entire tip surface is protected by the stainless insert, even if repeated impact of cooling water is applied, cavitation or the like is caused. Corrosion is less likely to occur. Also, corrosion due to various chemicals contained in the cooling water is less likely to occur.
Further, since it is not necessary to change the material of the entire thermostat housing, the weight of the housing is not increased, and the weight of the engine can be reduced.

In addition, the stainless steel insert covers the seating surface of the bypass passage opening / closing valve consisting of the entire tip surface of the tubular part, and the seating surface itself is made of stainless material, and the seating surface has high durability. Since the entire tip surface is covered, the valve and the seating surface can be stably brought into contact with and separated from each other.

Furthermore, it is only necessary to form a thick part of the thermostat housing, that is, a part corresponding to the bypass passage opening / closing valve, and it is not necessary to increase the entire thickness of the thermostat housing, so that the manufacturability is excellent. There is.

Further, a stainless insert was press-fitted onto the inner peripheral surface of the tubular portion formed by projecting a part of the inner surface of the thermostat housing inward and increasing the wall thickness of the part, or was mounted by molding at the time of molding the thermostat housing. Therefore, as compared with, for example, one in which an insert is fitted, a firmer mounted state can be obtained, and the insert can be held by the inner peripheral surface of the cylindrical portion, which has a long axial length, and the insert mounting stability can be improved. high.

<Example> Hereinafter, an example of the present invention will be described with reference to the drawings.

In FIG. 1, the same elements as those in FIG. 3 are designated by the same reference numerals to simplify the description.

In FIG. 1, the opening / closing valve of the bypass passage 2 is formed on the lower outer peripheral wall of the pellet 5 protruding from the lower frame 4B.
A ring 14 for restricting downward movement of 13 is fitted, and the opening / closing valve 13 is provided so as to be slidable with respect to the pellet 5, and is constantly elastically biased toward the ring 14 side by a spring 15. Is the same as the conventional one.

A tubular portion 12 formed by projecting a part of the inner surface of the thermostat housing H inward and increasing the wall thickness of the portion is provided, and the opening of the tubular portion 12 serves as the inlet of the bypass passage. At the same time, the entire tip end surface of the tubular portion 12 serves as the seating surface 8 of the bypass passage opening / closing valve 13, and the inner peripheral wall surface of the tubular portion 12 and the bypass passage opening / closing valve seating surface 8 including the entire tip end surface are formed. A substantially cylindrical stainless steel insert 16 is provided.

As shown in FIG. 2, this insert 16 has a cylindrical portion 12
It is composed of a cylindrical portion 16a covering the inner wall surface and an annular flange portion 16b integrally formed on the peripheral edge of one end of the cylindrical portion 16a and covering the opening / closing valve seating surface 8.

The insert 16 is attached to the inner peripheral surface of the tubular portion 12 by press fitting or casting at the same time when the housing H is molded.

According to the thermostat device having the above configuration, the inner wall surface of the tubular portion 12 and the seating surface 8 forming the bypass passage inlet portion are protected by the stainless insert 16,
Even if repeated impacts of cooling water are applied, corrosion such as cavitation hardly occurs. Also, corrosion due to various chemicals contained in the cooling water is less likely to occur.

Further, since it is not necessary to change the material of the entire thermostat housing H, the weight of the housing H is not increased, and the weight of the engine can be reduced.

In particular, in such a configuration, the stainless steel insert 16 covers the bypass passage opening / closing valve seating surface 8 formed of the entire end surface of the tubular portion 12, and the seating surface 8 itself is made of a stainless material, and the durability of the seating surface 8 is improved. High, the stainless steel insert 16 covers the entire tip surface of the tubular part 12,
13 and the seating surface 8 can be stably brought into contact with and separated from each other.

Further, the thickness of the thermostat housing H may be formed only in a necessary portion, that is, only a part corresponding to the bypass passage opening / closing valve 13 may be thickened.
The manufacturability is excellent because it is not necessary to increase the overall thickness of the.

In addition, a stainless insert 16 is press-fitted onto the inner peripheral surface of the tubular portion 12 formed by projecting a part of the inner surface of the thermostat housing H inward and increasing the wall thickness of the part, or casting at the time of molding of the thermostat housing H. Since it is mounted by inserting it, a stronger mounting state can be obtained compared to, for example, one in which an insert is fitted, and the insert 16 is held by the inner peripheral surface of the cylindrical portion 12 having a long axial length. The insert 16 is highly stable.

<Effects of the Invention> As described above, according to the thermostat device of the present invention, the corrosion resistance of the bypass passage inlet inner wall surface of the thermostat housing and the opening / closing valve seating surface of the inlet portion can be improved, and the weight of the engine can be improved. In particular, the seating surface has high durability, the insert is firmly mounted, the insert is highly stable, and the valve and the seating surface can be stably brought into contact with and separated from each other. At the same time, it is only necessary to form a thick part of the thermostat housing, that is, the part corresponding to the bypass passage opening / closing valve, and it is not necessary to increase the overall thickness of the thermostat housing, so manufacturability is also excellent. It has a great practical effect.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of an engine thermostat device according to the present invention, FIG. 2 is a perspective view of an insert in the same embodiment, and FIG. 3 is a sectional view showing an example of a conventional thermostat device. 2 ... Bypass passage, 8 ... Seating surface, 12 ... Cylindrical part, 13
…… Open / close valve, 16 …… Insert

Claims (1)

(57) [Scope of utility model registration request] 1. A thermostat device for an engine, which is interposed at a branch portion of a cooling water main passage connecting an engine body and a radiator, and a bypass passage extending directly from the engine body to the water pump without passing through the radiator. ,
A tubular portion formed by projecting a part of the inner surface of the thermostat housing inward and increasing the thickness of the portion is provided, and the opening of the tubular portion serves as an inlet portion of the bypass passage and the tubular shape The thermostat includes a substantially tubular insert made of stainless steel which covers the entire inner surface of the bypass passage opening / closing valve as a seating surface of the bypass passage opening / closing valve and covers the seating surface of the bypass passage opening / closing valve consisting of the entire inner surface of the tubular portion. A thermostat device for an engine, characterized in that the thermostat device is mounted on the inner peripheral surface of the tubular portion of the housing by press fitting or casting when molding the thermostat housing.