JP2001317656A - Thermostat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermostat having a simple structure and capable of suppressing the reduction of water temperature when an engine is started and improving fuel consumption performance and exhaust air purifying performance. SOLUTION: This thermostat is provided with a valve element 12 opening and closing a radiator circuit and a main opening and closing mechanism and an auxiliary spring (auxiliary opening and closing mechanism) 32 opening and closing the valve element 12 automatically. The main opening and closing mechanism opens and closes the valve element 12 against a spring force of a main spring 30 due to the shrinkage and expansion of wax (operation body) stored in a pellet 14 in accordance with a temperature of cooling water. When a flow rate or a pressure of cooling water are less than predetermined values even if the temperature is such temperature condition that opens the valve element by the main opening and closing mechanism, the valve element 12 is closed by a spring force of the auxiliary spring 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermostat provided in a heat exchange circuit for a fluid such as a water-cooled internal combustion engine or a water heater and capable of automatically opening and closing the heat exchange circuit in accordance with the temperature of the fluid.

[0002]

2. Description of the Related Art Conventionally, in a water-cooled internal combustion engine, a thermostat for opening and closing a radiator circuit of a cooling water provided with a radiator (heat exchanger) in order to suppress overcooling of the cooling water in a cold condition or the like. Is suitably provided. As such a thermostat, a wax type using a wax (operating body) that expands when the temperature of cooling water (fluid) in a temperature sensing portion becomes equal to or higher than a predetermined temperature is well known. When the water temperature is equal to or higher than the predetermined temperature, the valve of the radiator circuit is opened to reduce the water temperature, while when the water temperature is lower than the predetermined temperature, the radiator circuit is closed and the bypass bypasses the radiator. By circulating cooling water in the circuit, a decrease in water temperature is suppressed.

[0003]

By the way, in terms of fuel efficiency and exhaust purification, the cooling water temperature at the time of starting the engine is as follows.
It is preferable to be as high as possible. However, in the conventional thermostat as described above, if the water temperature of the temperature sensing portion is equal to or higher than a predetermined temperature, the radiator circuit valve is continuously opened even after the engine is stopped. Circulates through the radiator circuit, the water temperature drops rapidly, and the cooling water temperature at the next engine start also drops.

Therefore, it is conceivable to electrically control the drive of the valve so that the radiator circuit is closed while the engine is stopped. However, in this case, the structure is complicated and the cost is significantly increased with the electric control of the valve.

[0005] For example, Japanese Patent Application Laid-Open No. 10-77839 discloses a technique in which a heat storage tank is provided in a cooling water circuit of an internal combustion engine, and the heat stored in the heat storage tank is utilized when the engine is started. However, in this case, since a heat storage tank, a control valve associated therewith, and an electric control mechanism of the control valve are required, the structure is complicated and the cost is significantly increased.

The present invention has been made in view of such a problem, and in addition to automatically opening and closing a heat exchange circuit in accordance with the temperature of a fluid, automatically adjusting the flow rate or pressure of the fluid. A main object of the present invention is to provide a novel thermostat that can maintain a fluid temperature at an appropriate temperature with a simple structure by opening and closing a heat exchange circuit.

In particular, when applied to a water-cooled internal combustion engine, the main object is to suppress a decrease in the cooling water temperature when the engine is stopped and to effectively save the heat of the cooling water until the engine is started.

[0008]

SUMMARY OF THE INVENTION A thermostat according to the present invention is suitably applied to, for example, a water-cooled internal combustion engine, and is provided in a heat exchange circuit for fluid (cooling water). The valve body is provided. And it is characterized by having a main opening and closing mechanism for automatically opening and closing the valve body in response to a temperature change of the fluid, and a sub opening and closing mechanism for automatically opening and closing the valve body in accordance with the flow rate or pressure of the fluid. . Thus, the temperature of the fluid can be more appropriately managed by opening and closing the heat exchange circuit in accordance with the temperature and the flow rate or the pressure of the fluid with a simple structure.

More specifically, for example, even if the temperature is to be opened by the main opening / closing mechanism, if the flow rate or pressure of the fluid is less than a predetermined value, the auxiliary opening / closing mechanism is used. Close the valve. Thus, for example, when applied to a water-cooled internal combustion engine, when the engine speed is low (ie, when the flow rate or pressure of the cooling water is less than a predetermined value) such as when the engine is stopped, the water temperature of the cooling water temporarily becomes Even when the temperature is equal to or higher than the temperature (that is, the temperature condition to be opened by the main opening / closing mechanism), the heat exchange circuit is closed by the sub opening / closing mechanism. For this reason, the cooling water does not circulate through the heat exchanger such as the radiator, so that the cooling water temperature is prevented from lowering, and the heat of the cooling water can be effectively stored until the next start. Therefore, it is possible to improve the fuel consumption performance and the exhaust purification performance at the time of starting the engine.

The above-mentioned sub-opening / closing mechanism has a simple structure having a sub-biasing member for urging the valve body in the valve closing direction against the flow or pressure of the fluid.

The main opening / closing mechanism preferably includes a main urging member for urging the valve body in a valve closing direction, and the valve body is urged by the main urging member in accordance with the fluid temperature of the temperature sensing portion. And an actuating body for performing an opening operation in opposition.

More specifically, a pellet accommodating the operating body, a piston protruding from the pellet so as to be able to advance and retreat, being inserted into the valve body and abutting against the fixed housing, and being advanced and retracted by the operating body. Wherein the main biasing member is interposed between the pellet and the fixed housing, and is a main spring for biasing the pellet in a valve closing direction of the valve body, and the sub-biasing member is This is a sub-spring interposed between the valve element and the pellet.

[0013] More preferably, there is provided an auxiliary valve element for opening and closing a bypass circuit provided in the heat exchange circuit and bypassing the heat exchanger, and the auxiliary valve element is closed at least when the valve element is open. The main opening and closing mechanism automatically opens and closes.

[0014]

According to the present invention, by automatically opening and closing the heat exchange circuit in accordance with the temperature and flow rate or pressure of the fluid, it is possible to more appropriately manage the temperature of the fluid with a simple structure. it can.

In particular, when the present invention is applied to a water-cooled internal combustion engine, for example, when the engine is stopped, the cooling water is reliably prevented from circulating to a heat exchanger such as a radiator, and the heat of the cooling water is reduced until the next start. Can be stored effectively. Therefore,
It is possible to improve the fuel consumption performance and the exhaust purification performance at the time of starting the engine.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a thermostat according to the present invention is applied to a cooling device for a water-cooled internal combustion engine will be described in detail below with reference to the drawings.

FIG. 4 shows the overall configuration of the cooling device. The cooling device is provided with a radiator circuit (heat exchange circuit) A through which cooling water circulates along a solid line arrow, and the radiator circuit A includes a water-cooled internal combustion engine 1.
, A radiator 2, a water pump 3, and a thermostat 10 according to the present embodiment. A cooling water path indicated by a broken line in FIG. 4 represents a bypass circuit B that circulates inside the internal combustion engine 1 without bypassing the radiator 2.

In the internal combustion engine 1, an inlet 4 into which cooling water flows from the radiator 2 side is provided in the cylinder block 1a, and an outlet 5 through which cooling water flows out to the radiator 2 side is provided in the cylinder head 1b. A water jacket 6 through which cooling water flows is formed inside. As is well known, the radiator 2 is a heat exchanger that cools the cooling water that has become hot while passing through the internal combustion engine 1, and is generally provided at the front of the vehicle so that the vehicle wind can be effectively used. Are located. Water pump 3
Is for applying a discharge pressure to the cooling water and forcibly circulating the cooling water. A driving pulley 3b is provided at the tip of the pump shaft 3a,
The pulley 3b is driven by a crankshaft via a belt or a chain (not shown).

The thermostat 10 is provided on the inlet 4 side (or outlet 5 side) of the internal combustion engine 1 and mainly opens and closes a radiator circuit A as described later. The thermostat 10 has a first inflow passage 7 into which cooling water flows from the inlet 4 side, a second inflow passage 8 for returning cooling water from the cylinder head 1b side, and an outflow passage through which cooling water flows out to the water pump 3 side. 9 are connected. The first inflow passage 7 forms a part of the radiator circuit A, the second inflow passage 8 forms a part of the bypass circuit B, and the outflow passage 9 forms a part of both circuits A and B. .

1 to 3 are sectional views showing the thermostat 10 in detail. This thermostat 10
Includes a valve element 12 for opening and closing the first inflow passage 7 constituting the radiator circuit A, and automatically switches the valve element 12 in accordance with the temperature of the cooling water in the temperature sensing section (that is, by electric control or the like). A main opening and closing mechanism that opens and closes spontaneously and mechanically)
A sub-opening / closing mechanism for automatically opening / closing according to the flow rate or pressure of the cooling water.

In this embodiment, the main opening / closing mechanism is a so-called wax type utilizing a volume expansion of a wax (not shown) as an operating body accommodated in the pellet 14, and the water temperature of the wax is a predetermined temperature T. If it is more than this, the volume expands, and if it is less than that, it contracts.

The pellets 14 are supported by a fixed housing 16 fixed to the cylinder block 1a (FIG. 4) so as to be movable in the axial direction of the pellets 14.
The fixed housing 16 includes an annular flange 18 provided with a seat portion 18 a of the valve body 12 and a piston support member 2.
0, and a spring support member 22, and these three members 18, 20, 22 are caulked and fixed to each other at a caulking portion 24.

The pellet 14 is provided with a piston 26 which moves forward and backward in accordance with shrinkage and expansion of the wax. The piston 26 protrudes from one end of the pellet 14, and a distal end extending through the central hole 12 a of the valve body 12 is fixed to the piston support member 20. It is movably supported.
A support bracket 28 is fixed to the outer periphery of the pellet 14, and between the support bracket 28 and the spring support member 22, the valve body 12 is biased in a valve closing direction (downward in FIGS. 1 to 3). A spring (main biasing body) 30 is interposed.

A sub-spring (sub-biasing member) 32 for urging the valve body 12 in the valve closing direction is interposed between the support bracket 28 and the valve body 12.
Constitute the above-mentioned sub-opening / closing mechanism. Then, a state in which the pellet 14 is located in the valve opening direction of the valve body 12 (FIG. 2,
3), the auxiliary spring 3 opens and closes so that the valve element 12 opens and closes in accordance with the flow rate of the cooling water flowing between the valve element 12 and the seating portion 18a or the water pressure acting on the valve element 12.
2 is set in advance, and this spring constant is
At least it is set sufficiently smaller than the spring constant of the main spring 30. Here, the flow rate of the cooling water is substantially proportional to the discharge pressure of the water pump 3 and the rotation speed of the crankshaft that drives the water pump 3.
Therefore, if the flow rate (or pressure), discharge pressure, engine speed, or the like of the cooling water is equal to or greater than the predetermined value Q, the valve body 12 opens against the spring force of the sub-spring 32, If there is, the spring force of the auxiliary spring 32 is set so as to close the flow and pressure of the cooling water and close the valve body 12.

A support rod 34 is formed integrally with the other end of the pellet 14 (the upper end in FIGS. 1 to 3). The support rod 34 is connected to a port of the second inflow passage 8 constituting the bypass circuit B. An auxiliary valve element 36 for opening and closing the section is provided. An auxiliary spring 38 is interposed between the auxiliary valve element 36 and the pellet 14 main body. These springs 32, 38 ensure that the respective valve bodies 12, 36 are pressed against the port peripheral portion when the valve is closed.

FIG. 1 shows a state when the water temperature is lower than a predetermined temperature T. In this case, the wax shrinks,
Due to the spring force of the main spring 30, the piston 26 is most retracted into the pellet 14, that is, the pellet 1
4 is located closest to the valve closing side of the valve body 12 (the lower side in FIG. 1). As a result, the end face (the lower end face in FIG. 1) of the pellet 14 abuts against the valve body 12, and the valve body 12 is pressed against the seat 18a. That is, if the water temperature of the temperature sensing portion is lower than the predetermined temperature T, the valve body 12 is seated on the seat portion 18a regardless of the flow rate of the cooling water. For this reason,
The valve element 12 is closed and the radiator circuit A is closed, while the auxiliary valve element 36 is opened and the bypass circuit B is opened. Therefore, the cooling water flows from the second inflow passage 8 to the outflow passage 9 as shown by the arrow in FIG. 1 and can circulate in the bypass circuit B.

FIG. 2 shows that the water temperature is equal to or higher than a predetermined temperature T, and
The state when the flow rate of the cooling water is equal to or more than the predetermined value Q is shown. In this case, since the wax expands, the piston 26
Is pushed out from the pellet 14, and as a result, the pellet 14 moves and is arranged in the valve opening direction of the valve body 12 (upward in FIG. 2) against the spring force of the main spring 30. Thereby, the auxiliary valve body 36 closes the second inflow passage 8, and the bypass circuit B is closed.

Further, the support bracket 28 is most suitable for the valve body 12.
2 and the flow rate of the cooling water is equal to or greater than the predetermined value Q, the valve body 12 resists the spring force of the auxiliary spring 32 due to the flow and pressure of the cooling water. The valve body 12 is pressed in the valve opening direction of the valve body 12 so that the valve body 12
It is opened apart from 8a. Therefore, the cooling water can circulate through the radiator circuit A as shown by the arrow in FIG.

FIG. 3 shows a state where the water temperature is equal to or higher than the predetermined temperature T and the flow rate is lower than the predetermined value Q. In this case, as in the case of FIG. 2, since the wax expands, the piston 26 is pushed out of the pellet 14, and
As a result, the pellet 14 is arranged in the valve opening direction of the valve body 12 (upward in FIG. 3) most against the spring force of the main spring 30. Thereby, the auxiliary valve body 36 closes the second inflow passage 8, and the bypass circuit B is closed.

As in the case of FIG. 2, the support bracket 28 moves most in the valve opening direction of the valve body 12 (upward direction in FIG. 3). The spring 32 overcomes the pressure of the cooling water and presses the valve body 12 in the valve closing direction (downward in the figure), and the valve body 12 is seated on the seat 18a to close the radiator circuit A.

Therefore, even if the water temperature is equal to or higher than the predetermined temperature T, for example, immediately after the engine is stopped, if the engine speed is low and the flow rate (or pressure) of the cooling water is sufficiently low, both valve bodies 12 , 36 are closed, and there is no possibility that the cooling water inside the internal combustion engine 1 circulates to the radiator 2 side. That is, after the engine stops, the internal combustion engine 1 functions as a kind of heat storage tank, and the heat of the cooling water is effectively held. Accordingly, a decrease in water temperature is effectively suppressed until the next start of the engine, so that fuel consumption can be reduced and exhaust gas can be purified. In particular,
In the case where the engine stop and start are frequently repeated, it is possible to effectively suppress the temperature drop of the cooling water.

Further, since there is no need to use an electric drive control mechanism or the like unlike the prior art, the structure is simple, the cost is advantageous, and the vehicle is excellent in mountability.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a cooling device for an internal combustion engine to which a thermostat according to the present invention is applied.

FIG. 2 is a cross-sectional view showing a state of the thermostat of FIG. 1 at a low temperature.

FIG. 3 is a cross-sectional view showing a mode of the thermostat of FIG. 1 at a high temperature and a high flow rate.

FIG. 4 is a cross-sectional view showing a state of the thermostat of FIG. 1 at a high temperature and a low flow rate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Thermostat 12 ... Valve 14 ... Pellet (main opening / closing mechanism) 16 ... Fixed housing 30 ... Main spring (main biasing body) 32 ... Secondary spring (sub biasing body) 36 ... Auxiliary valve body A ... Radiator circuit (heat Exchange circuit B: Bypass circuit

Claims (7)

[Claims] 1. A thermostat provided in a heat exchange circuit for a fluid and provided with a valve for opening and closing the heat exchange circuit, wherein the main opening and closing mechanism automatically opens and closes the valve in response to a change in temperature of the fluid. And a sub-opening / closing mechanism that automatically opens and closes the valve body in accordance with the flow rate or pressure of the fluid. 2. The valve according to claim 1, wherein the valve element is closed by a sub-opening / closing mechanism when the flow rate or pressure of the fluid is less than a predetermined value, even if the temperature is to be opened by the main opening / closing mechanism. The thermostat according to claim 1. 3. The thermostat according to claim 1, wherein the sub-opening / closing mechanism has a sub-biasing member that urges the valve body in the valve closing direction against the flow or pressure of the fluid. . 4. The main opening / closing mechanism for urging the valve body in a valve closing direction and for urging the valve body against the urging force of the main urging body in accordance with the fluid temperature of the temperature sensing part. The thermostat according to claim 3, further comprising: an actuating body for performing an opening operation. 5. A pellet containing the operating body, and a piston projecting from the pellet so as to be able to advance and retreat, being inserted into the valve body and abutting against a fixed housing, and being advanced and retracted by the operating body. The main urging member is interposed between the pellet and the fixed housing, and is a main spring that urges the pellet in a valve closing direction of the valve element. The thermostat according to claim 4, wherein the thermostat is a sub-spring interposed between the pellet and the pellet. 6. An auxiliary valve element for opening and closing a bypass circuit bypassing a heat exchanger provided in the heat exchange circuit, wherein the auxiliary valve element is closed at least when the valve element is opened. 6. The thermostat according to claim 1, wherein the thermostat is automatically opened and closed by the main opening and closing mechanism. 7. The thermostat according to claim 1, wherein the fluid is cooling water for a water-cooled internal combustion engine.