JP3711837B2 - thermostat - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermostat that is provided in a fluid heat exchange circuit such as a water-cooled internal combustion engine or a water heater, and that can automatically open and close the heat exchange circuit according to the temperature of the fluid.
[0002]
[Prior art]
Conventionally, a water-cooled internal combustion engine is preferably provided with a thermostat for opening and closing a cooling water radiator circuit provided with a radiator (heat exchanger) in order to suppress overcooling of the cooling water during cold weather. . As such a thermostat, a wax type using a wax (operating body) that expands when the temperature of the cooling water (fluid) in the temperature-sensing part becomes a predetermined temperature or higher is well known. When the water temperature is higher than the predetermined temperature, the valve of the radiator circuit is opened to lower the water temperature. On the other hand, when the water temperature is lower than the predetermined temperature, the radiator circuit is closed and the bypass is bypassed without going through the radiator. By circulating the cooling water in the circuit, a decrease in the water temperature is suppressed.
[0003]
[Problems to be solved by the invention]
By the way, in terms of fuel consumption performance and exhaust gas purification, it is preferable that the coolant temperature at the time of engine start is as high as possible. However, in the conventional thermostat as described above, if the water temperature of the temperature sensing unit is equal to or higher than a predetermined temperature, the valve of the radiator circuit is kept open even after the engine is stopped. However, by circulating through the radiator circuit, the water temperature rapidly decreases, and the cooling water temperature at the next engine start also decreases.
[0004]
Thus, it is conceivable to electrically control 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 circuit of cooling water for an internal combustion engine, and heat stored in the heat storage tank is utilized when the engine is started. However, in this case, a heat storage tank, a control valve associated therewith, an electric control mechanism for the control valve, and the like are required, so that the structure is complicated and the cost is significantly increased.
[0006]
The present invention has been made in view of such problems, and in addition to automatically opening and closing the heat exchange circuit according to the temperature of the fluid, the heat exchange circuit automatically according to the flow rate or pressure of the fluid. The main object is to provide a novel thermostat capable of maintaining the fluid temperature at an appropriate temperature with a simple structure by opening and closing the.
[0007]
In particular, when applied to a water-cooled internal combustion engine, the main purpose is to suppress a decrease in cooling water temperature when the engine is stopped and to effectively store the heat of the cooling water until the engine is started.
[0008]
[Means for Solving the Problems]
The thermostat according to the present invention is suitably applied to, for example, a water-cooled internal combustion engine, and is provided in a fluid (cooling water) heat exchange circuit, and opens and closes the heat exchange circuit, and the heat exchange circuit. And an auxiliary valve body that opens and closes a bypass circuit that bypasses the heat exchanger provided in the heat exchanger . A main opening / closing mechanism that automatically opens and closes the auxiliary valve body in response to a temperature change of the fluid; and when the auxiliary valve body is closed by the main opening / closing mechanism, the automatic opening / closing mechanism automatically It is characterized by having to the auxiliary switching mechanism for opening and closing the valve, the. Thereby, the temperature of the fluid can be more appropriately managed by opening and closing the heat exchange circuit according to the temperature and flow rate or pressure of the fluid with a simple structure.
[0009]
Specifically, even if the temperature condition is to be opened by the main opening / closing mechanism, the valve body is closed by the auxiliary opening / closing mechanism when the flow rate or pressure of the fluid is less than a predetermined value. Thus, for example, when applied to a water-cooled internal combustion engine, if the engine speed is low (that is, when the flow rate or pressure of the cooling water is less than a predetermined value), such as when the engine is stopped, the cooling water temperature is temporarily set to a predetermined value. Even when the temperature is higher than the temperature (that is, the temperature condition that should be opened by the main opening / closing mechanism), the heat exchange circuit is closed by the auxiliary opening / closing mechanism. For this reason, cooling water does not circulate through a heat exchanger such as a radiator, so that a decrease in cooling water temperature is suppressed, and 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 when starting the engine.
[0010]
The sub opening / closing mechanism has a simple configuration including, for example, a sub urging member that urges the valve body in a valve closing direction against a fluid flow or pressure.
[0011]
The main opening / closing mechanism preferably has a main urging body for urging the valve body in a valve closing direction and the valve body against the urging force of the main urging body according to the fluid temperature of the temperature sensing unit. And a simple configuration having an actuating body that opens.
[0012]
More specifically, a pellet in which the operating body is accommodated, and a piston that protrudes from the pellet so as to advance and retract, is inserted into the valve body and is abutted against the fixed housing, and is advanced and retracted by the operating body. The main biasing body is interposed between the pellet and the fixed housing, and is a main spring that biases the pellet in the valve closing direction of the valve body, and the sub biasing body is the valve body. And a secondary spring interposed between the pellet and the pellet.
[0013]
More preferably, it has an auxiliary valve body that opens and closes a bypass circuit that bypasses a heat exchanger provided in the heat exchange circuit, and the auxiliary valve body is closed at least when the valve body is open. The main opening / closing mechanism automatically opens and closes.
[0014]
【The invention's effect】
According to the present invention, the temperature of the fluid can be managed more appropriately with a simple structure by automatically opening and closing the heat exchange circuit according to the temperature and flow rate or pressure of the fluid.
[0015]
In particular, when applied to a water-cooled internal combustion engine, for example, the cooling water is reliably prevented from circulating to a heat exchanger such as a radiator when the engine is stopped. Can be saved. Therefore, it is possible to improve the fuel consumption performance and the exhaust purification performance when starting the engine.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, 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 with reference to the drawings.
[0017]
FIG. 4 shows the overall configuration of this cooling device. The cooling device is provided with a radiator circuit (heat exchange circuit) A in which cooling water circulates along a solid arrow. The radiator circuit A includes a water-cooled internal combustion engine 1, a radiator 2, water A pump 3 and a thermostat 10 according to the present embodiment are provided. 4 represents a bypass circuit B that bypasses the radiator 2 and circulates inside the internal combustion engine 1 without passing through the radiator 2.
[0018]
In the internal combustion engine 1, an inlet 4 through 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, and is cooled inside. A water jacket 6 through which water flows is formed. As is well known, the radiator 2 is a heat exchanger that cools cooling water that has become hot while passing through the internal combustion engine 1, and is generally installed at the front of the vehicle so that vehicle speed wind can be used effectively. Has been placed. The water pump 3 forcibly circulates by applying discharge pressure to the cooling water. A driving pulley 3b is provided at the tip of the pump shaft 3a, and this pulley 3b is connected to the crankshaft by a belt or chain (not shown). Driven.
[0019]
The thermostat 10 is disposed on the inlet 4 side (or outlet 5 side) of the internal combustion engine 1 and mainly opens and closes the radiator circuit A as will be described later. The thermostat 10 includes a first inflow passage 7 through which cooling water flows from the inlet 4 side, a second inflow passage 8 that returns the cooling water from the cylinder head 1b side, and an outflow passage through which the cooling water flows out to the water pump 3 side. 9 are connected. The first inflow passage 7 constitutes a part of the radiator circuit A, the second inflow passage 8 constitutes a part of the bypass circuit B, and the outflow passage 9 constitutes a part of both the circuits A and B. .
[0020]
1 to 3 are cross-sectional views showing the thermostat 10 in detail. The thermostat 10 includes a valve body 12 that opens and closes the first inflow passage 7 constituting the radiator circuit A, and the valve body 12 is automatically (that is, electrically controlled) according to the coolant temperature in the temperature sensing section. A main opening / closing mechanism that opens and closes spontaneously and mechanically (regardless of, etc.) and a sub-opening / closing mechanism that automatically opens and closes according to the flow rate or pressure of the cooling water.
[0021]
In this embodiment, the main opening / closing mechanism is a so-called wax type utilizing the volume expansion of wax (not shown) as an actuating body accommodated in the pellet 14, and this wax has a water temperature not lower than a predetermined temperature T. If it is less than that, it will shrink.
[0022]
The pellet 14 is supported by a fixed housing 16 fixed to the cylinder block 1a (FIG. 4) side so as to be movable in the axial direction of the pellet 14. The fixed housing 16 includes an annular flange 18 provided with a seating portion 18 a of the valve body 12, a piston support member 20, and a spring support member 22, and these three members 18, 20, 22 are included. Are caulked and fixed to each other by a caulking portion 24.
[0023]
The pellet 14 is provided with a piston 26 that advances and retreats according to the contraction and expansion of the wax. The piston 26 protrudes from one end of the pellet 14, and a distal end portion extending by loosely inserting the central hole portion 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 the valve body 12 is biased in the valve closing direction (downward in FIGS. 1 to 3) between the support bracket 28 and the spring support member 22. A spring (main biasing body) 30 is interposed.
[0024]
Further, a sub spring (sub urging member) 32 that urges the valve body 12 in the valve closing direction is interposed between the support bracket 28 and the valve body 12, and the sub spring 32 performs the above described sub opening / closing. The mechanism is configured. In the state where the pellet 14 is positioned in the valve opening direction of the valve body 12 (the state shown in FIGS. 2 and 3), the flow rate of the cooling water flowing between the valve body 12 and the seating portion 18a or the valve body 12 The spring constant of the auxiliary spring 32 is set in advance so that the valve body 12 opens and closes according to the acting water pressure, and this spring constant is set to be sufficiently smaller than at least 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 rotational speed of the crankshaft that drives the water pump 3. Therefore, if the flow rate (or pressure), discharge pressure, engine speed, etc. 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 auxiliary spring 32 and is less than the predetermined value Q. If so, the spring force of the auxiliary spring 32 is set so that the valve body 12 is closed by overcoming the flow and pressure of the cooling water.
[0025]
A support rod 34 is integrally formed at the other end of the pellet 14 (upper end in FIGS. 1 to 3). The support rod 34 opens and closes the port portion of the second inflow passage 8 constituting the bypass circuit B. An auxiliary valve body 36 is provided. An auxiliary spring 38 is interposed between the auxiliary valve body 36 and the pellet 14 main body. These springs 32 and 38 ensure that the respective valve bodies 12 and 36 are pressed against the peripheral edge of the port when the valve is closed.
[0026]
FIG. 1 shows a state when the water temperature is lower than the predetermined temperature T. In this case, since the wax contracts, the piston 26 is most retracted into the pellet 14 by the spring force of the main spring 30, that is, the pellet 14 is closest to the valve element 12 on the valve closing side (lower side in FIG. 1). It will be in an arranged state. As a result, the end surface (the lower end surface in FIG. 1) of the pellet 14 abuts against the valve body 12, and the valve body 12 is pressed against the seating portion 18a. That is, if the water temperature of the temperature sensing part is lower than the predetermined temperature T, the valve body 12 is seated on the seating part 18a regardless of the flow rate of the cooling water. Therefore, the valve body 12 is closed and the radiator circuit A is closed, while the auxiliary valve body 36 is opened and the bypass circuit B is opened. Accordingly, the cooling water flows from the second inflow passage 8 to the outflow passage 9 as shown by the arrows in FIG.
[0027]
FIG. 2 shows a state where the water temperature is equal to or higher than the predetermined temperature T and the flow rate of the cooling water is equal to or higher than the predetermined value Q. In this case, since the wax expands, the piston 26 is pushed out from the pellet 14. As a result, the pellet 14 resists the spring force of the main spring 30 and opens the valve body 12 (upward direction in FIG. 2). Moved to and placed. Thereby, the auxiliary valve body 36 closes the second inflow passage 8 and the bypass circuit B is closed.
[0028]
Further, since the support bracket 28 moves most in the valve opening direction of the valve body 12 (upward in FIG. 2) and the flow rate of the cooling water is equal to or greater than the predetermined value Q, the valve body 12 is caused by the flow and pressure of the cooling water. Is pressed against the spring force of the auxiliary spring 32 in the valve opening direction of the valve body 12, and the valve body 12 is opened away from the seating portion 18a. Therefore, the cooling water can circulate through the radiator circuit A as shown by the arrows in FIG.
[0029]
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 from the pellet 14, and as a result, the pellet 14 opens the valve body 12 most against the spring force of the main spring 30. It arrange | positions in a direction (upward direction of FIG. 3). Thereby, the auxiliary valve body 36 closes the second inflow passage 8 and the bypass circuit B is closed.
[0030]
As in the case of FIG. 2, the support bracket 28 moves most in the valve opening direction of the valve body 12 (upward in FIG. 3). However, since the flow rate of the cooling water is less than the predetermined value Q, the auxiliary spring 32 is The valve body 12 is pushed in the valve closing direction (downward in the figure) by overcoming the pressure of the cooling water, and the valve body 12 is seated on the seating portion 18a and the radiator circuit A is closed.
[0031]
Therefore, for example, immediately after the engine is stopped, even if the water temperature is equal to or higher than the predetermined temperature T, both the valve bodies 12 and 36 can be used if the engine speed is low and the flow rate (or pressure) of the cooling water is sufficiently low. 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 is stopped, the internal combustion engine 1 functions as a kind of heat storage tank, and the heat of the cooling water is effectively held. Therefore, a decrease in water temperature is effectively suppressed until the next engine start, and fuel consumption can be reduced and exhaust gas can be purified. In particular, when the engine stop and start are frequently repeated, the temperature drop of the cooling water can be effectively suppressed.
[0032]
In addition, since it is not necessary to use an electric drive control mechanism or the like as in the prior art, the structure is simple, advantageous in terms of cost, and excellent in vehicle mounting properties.
[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 state of the thermostat of FIG. 1 at a high temperature and a high flow rate.
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]
10 ... Thermostat 12 ... Valve body 14 ... Pellet (main opening / closing mechanism)
16 ... fixed housing 30 ... main spring (main biasing body)
32 ... sub spring (sub bias member)
36 ... Auxiliary valve element A ... Radiator circuit (heat exchange circuit)
B ... Bypass circuit

Claims (7)

A valve body that is provided in the fluid heat exchange circuit and opens and closes the heat exchange circuit ;
An auxiliary valve body that opens and closes a bypass circuit that bypasses the heat exchanger provided in the heat exchange circuit;
A main opening / closing mechanism for automatically opening / closing the auxiliary valve body in accordance with a temperature change of the fluid;
When the auxiliary valve body is closed by the main opening and closing mechanism, the auxiliary switching mechanism for automatically opening and closing the valve in response to the flow rate or pressure of the fluid,
A thermostat characterized by comprising: The valve body is closed by the sub-opening / closing mechanism when the auxiliary valve body is closed by the main opening / closing mechanism, regardless of the flow rate or pressure of the fluid. Thermostat.   The thermostat according to claim 1 or 2, wherein the sub opening / closing mechanism has a sub urging member that urges the valve body in a valve closing direction against a flow or pressure of fluid. Closing the main opening and closing mechanism, against the auxiliary valve and the main biasing body biases the valve opening direction, the biasing force of the main biasing member to the auxiliary valve body in response to the fluid temperature of the temperature sensing portion The thermostat according to claim 3, further comprising an actuating body to be actuated. A pellet in which the operating body is accommodated, and a piston that protrudes forward and backward from the pellet, is inserted into the valve body, is abutted against a fixed housing, and is advanced and retracted by the operating body,
The main urging body 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 body,
The thermostat according to claim 4, wherein the auxiliary biasing body is a secondary spring interposed between the valve body and the pellet. When the temperature of the fluid is lower than a predetermined temperature, the auxiliary valve body is opened by the main opening / closing mechanism,
When the fluid temperature is equal to or higher than a predetermined temperature and the flow rate or pressure of the cooling water is equal to or higher than a predetermined value, the auxiliary valve body is closed by the main opening / closing mechanism, and the valve body is opened by the sub opening / closing mechanism,
When the fluid temperature is equal to or higher than a predetermined temperature and the flow rate or pressure of the cooling water is less than a predetermined value, the auxiliary valve body is closed by the main opening / closing mechanism and the valve body is closed by the sub opening / closing mechanism.
The thermostat according to any one of claims 1 to 5.   The thermostat according to any one of claims 1 to 6, wherein the fluid is cooling water for a water-cooled internal combustion engine.

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