JP2001342833A - Thermostat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermostat capable of keeping suitable compatibleness between suppress of hunting of coolant temperature and improvement of fuel consumption performance of an engine and easily providing a desired characteristic. SOLUTION: This thermostat 20 is disposed in a coolant passage for connecting water cooling engine and a radiator. Melting bodies W1 and W2 melting depending on the coolant temperature are stored in a wax case 21, and a valve element 21a having opening amount varying with volume change of the melting bodies controls the coolant temperature by varying flow amount of the coolant. The melting body W1 starts melting at a temperature A capable of accelerating evaporation of fuel supplied to the engine. The melting body W2 is wax composed of a single component, and starts melting at a temperature B higher than the temperature A, at which the engine transfers to a high load operation. The cases R1 and R2 for storing the melting bodies W1 and W2, respectively, are disposed so as to both contact the coolant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a melt (wax) thermostat used for temperature control of a water-cooled engine or the like.

[0002]

2. Description of the Related Art Conventionally, as this type of thermostat, for example, the one described in Japanese Patent Application Laid-Open No. 63-219975 is known.

That is, as shown in FIG. 8, a thermostat 60 of this type normally cools between a water jacket (not shown) provided inside a water-cooled engine 11 and a radiator 12 as a heat exchanger. In a cooling water channel provided to circulate water, it is used as a device for automatically controlling the temperature of the cooling water.

FIG. 9 shows the internal structure of the thermostat 60. As shown in FIG.
Is provided with a wax case 61 formed of a hard material into a bottomed cylindrical shape and having a guide 22 made of hard rubber, resin, or the like fitted therein. The guide 22 inside the wax case 61
A rod case 23 formed in a bag shape from an elastic material such as rubber is provided on the lower surface of the rubber case. A wax W is filled between the wax case 61 and the rod case 23.

On the other hand, a rod 25 is inserted into the rod case 23 so that one end thereof protrudes outward from the case 23 via the guide 22. The upper end of the rod 25 is in contact with a bracket 26 fixed in the cooling water passage, so that upward movement is restricted. The bracket 26 itself is formed in a substantially rectangular plate shape when viewed from the plane, and has a structure that does not hinder the flow of cooling water. Has become. Further, for example, a disc-shaped valve body 21a is fixed to the wax case 61, and an annular seal member 26 is provided on the upper surface of the valve body 21a.
b is attached. Then, with the valve element 21a being seated on the valve seat 26a via the seal member 26b, the entire water channel of the cooling water channel is closed.

On the other hand, a bracket 26c is provided below the valve seat 26a in a manner shown in FIG. 9 so that the bracket 26c and the valve body 21a fixed to the wax case 61 are connected to each other. A spring 27 is provided between them. The wax case 61 is attached to the bracket 26c so that the valve body 21a is pressed against the valve seat 26a by the spring 27. The wax case 61 is provided with the valve body 21a and the valve seat 26.
With respect to the bracket a or the bracket 26c, the bracket 26c can be moved downward.

The thermostat 6 having such a structure
0, if the temperature of the cooling water in which the wax case 61 is immersed is lower than the melting point of the wax W,
The state shown in FIG. 9, that is, the valve body 21a is
a is maintained. In this state,
The cooling channel is closed.

On the other hand, when the temperature of the cooling water becomes higher than the melting point of the wax W, the volume of the wax W expands with the phase transition. That is, the rod 25 is pushed out of the rod case 23. However, as described above, since the upper end of the rod 25 is in contact with the bracket 26 and its movement is restricted, the wax case 61 itself resists the urging force of the spring 27 and The body 21a moves in a direction away from the valve seat 26a. At this time, the cooling water heated by the operation of the engine 11 passes through this gap.
2 will be supplied.

As described above, by providing the thermostat 60 in the cooling water passage, the flow rate of the cooling water supplied to the radiator 12 is adjusted according to the change of the cooling water temperature. Then, the cooling water exchanged by the radiator 12 is supplied to the engine 11 again,
The temperature of the engine 11 is adjusted.

[0010]

By the way, in the conventional thermostat 60, the change of the valve opening amount with respect to the change of the cooling water temperature of the valve, that is, the inclination, is naturally determined by the characteristics of the wax W. In addition, the temperature at which the valve should be fully opened is automatically determined from the viewpoint of preventing the engine 11 from overheating. For this reason,
For example, when the inclination is set to be small through the characteristics of the wax, the temperature of the cooling water for opening the valve is set to a low temperature. That is, the valve is opened in a state where the temperature of the cooling water has not increased so much, and the warm-up performance of the engine is reduced. This means that the time during which the engine is operated in a state where the engine resistance is large is prolonged, and the fuel economy performance is reduced.

On the other hand, when the inclination is set to be large through the characteristics of the wax, the temperature of the cooling water for opening the valve can be set to a relatively high temperature. Performance degradation can be prevented.
However, in this case, since the change in the valve opening amount of the valve with respect to the change in the cooling water temperature becomes large, the change amount of the cooling water temperature accompanying the change also becomes large, resulting in so-called hunting in which the cooling water temperature repeatedly rises and falls. Become like Incidentally, in recent years, this cooling water temperature is, for example, the drive of a cooling fan,
Since it is used as a control parameter for various control objects, when hunting occurs in the cooling water temperature in this way, the comfort state is reduced, for example, the operation state of each control object changes frequently.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to easily achieve desired characteristics while suppressing the hunting of the cooling water temperature and improving the fuel efficiency of the engine. To provide a thermostat that can be obtained from

[0013]

The means for achieving the above object and the effects thereof will be described below. The invention according to claim 1 is a thermostat in which the first and second melts are individually stored, wherein the melts are:
Melting is started at a first temperature, and after the start of melting, a first volume change rate with a first rate of change of volume with a change in temperature.
And melting is started at a second temperature higher than the first temperature, and after the start of melting, the volume is changed with the temperature change at a second volume change rate higher than the first volume change rate. The gist of the present invention is to provide a changing second melt.

In the above configuration, when the temperature of the thermostat itself becomes higher than the second temperature, the valve opening amount changes with the temperature change with the second volume change rate higher than the first volume change rate. Become like That is, the change (gradient) of the valve opening amount of the valve with respect to the temperature at this time is as follows:
The temperature is higher than when the temperature is lower than the second temperature.

As described above, according to the first aspect of the present invention, when the temperature of the thermostat itself is lower than the second temperature, the inclination can be made relatively small. On the other hand, when the temperature is higher than the second temperature, the inclination can be increased, and the valve opening amount of the valve can be quickly increased. Moreover, the first temperature at which the valve is opened can be set higher by an amount corresponding to increasing the inclination. In other words, desired characteristics can be easily obtained while suitably suppressing the hunting of the cooling water temperature and improving the fuel efficiency of the engine.

According to a second aspect of the present invention, in the thermostat according to the first aspect, the first temperature at which the melting of the first melt is started is a temperature at which vaporization of fuel supplied to the engine can be promoted. The gist is that the second temperature at which the melting of the second melt is started is the transition temperature to the high-load operation of the engine.

According to the above configuration, the valve can be prevented from being opened until the temperature of the cooling water reaches a temperature at which the vaporization of the fuel supplied to the engine is promoted. Then, after the valve is opened, the gradient of the valve opening amount of the valve can be reduced during normal load operation of the engine, and the valve opening amount of the valve can be increased immediately during high load operation of the engine. As a result, overheating of the engine can be prevented. In this manner, the inclination of the valve opening amount of the valve can be switched according to the operating state of the engine.

The third aspect of the present invention is the first or second aspect.
The subject matter of the thermostat, wherein the second melt comprises a single-component wax. Usually, since the melt used for the thermostat is composed of a plurality of components, the inclination of the valve opening amount with respect to the temperature of the thermostat itself is such that the plurality of components are sequentially melted according to the change in the same temperature. This results in a predetermined inclination.

In this respect, according to the above configuration, since the wax composed of a single component is applied as the second melt, the wax is melted at once when the temperature reaches a predetermined temperature. And the valve can be fully opened more quickly.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of a thermostat according to the present invention will be described below with reference to FIGS. The cooling channel to which the thermostat of the present embodiment is applied is shown in FIG.
It is assumed that the configuration is the same as that of the conventional cooling water channel shown in FIG. In FIG. 1, the same elements as those of the conventional thermostat illustrated in FIG. 9 are denoted by the same reference numerals, and redundant description of those common elements will be omitted.

As shown in FIG. 1, a thermostat 20 according to the present embodiment has a wax case 21 which vertically partitions a bottom surface of the wax case 21 and a lower end of the rod case 23. For example, a wall-shaped partition 28 made of an elastic member such as a thin-film rubber is provided. That is, the partition 28 is configured such that the inside of the wax case 21 forms two upper and lower cases, and both cases come into contact with the cooling water.

Then, among those cases,
That is, the melt W1 is accommodated in the case R1 located on the rod case 23 side, and the melt R2 consisting of a single component is filled in the case R2 located below, that is, on the bottom side of the wax case 21. . Accordingly, the valve body 21a has a structure in which the valve opening amount is controlled in accordance with a change in the volume of each of the melts W1 and W2.

As the melt W2, a melt having a smaller melting temperature range than that of a conventional melt is selectively applied. That is, FIG.
As shown in FIG. 5, among the melts having various melting temperature ranges (lines L1 to L3), the melting temperature range of the conventional melt (line L1 to L3)
The melt (line L) whose melting temperature width is smaller compared to 1)
3) is applied. The temperatures A and B, which are the melting points of the melts W1 and W2, satisfy the requirements described below.

The temperature A, which is the melting point of the melt W1, is a temperature (for example, 90 degrees) at which the vaporization of the fuel supplied to the engine 11 is promoted. The temperature B, which is the melting point of the melt W2, is the temperature (for example, 100 degrees) at which the engine 11 shifts to the high load operation state. Further, the accommodation amount of the melt W1 is set so small that the inclination of the valve opening amount of the valve body 21a with respect to the cooling water temperature can suppress occurrence of hunting in the cooling water temperature.

The operation of the thermostat 20 configured as described above in accordance with a change in the cooling water temperature will be described below with reference to FIG. FIG. 3 shows the relationship between the cooling water temperature in the thermostat 20 and the valve opening amount of the valve body 21a.

As shown in FIG. 3, when the cooling water temperature is lower than the temperature A, the melts W1 and W2 do not melt. That is, the cooling water passage is closed, and the temperature of the cooling water quickly rises to a temperature at which the vaporization of the fuel supplied to the engine 11 can be promoted, so that the warm-up performance of the engine 11 is improved.

When the cooling water temperature rises to the temperature A, the melt W1 starts a phase transition and expands in volume, so that the valve 21a opens. Then, as long as the cooling water temperature does not become equal to or higher than the temperature B which is the melting point of the melt W2 due to the high load operation of the engine 11, the valve opening amount of the valve body 21a is increased by the volume expansion of the melt W1. Adjusted. In addition, the valve body 21a with respect to the change of the cooling water
, The change in the flow rate of the cooling water with respect to the change in the cooling water temperature is relatively small.

Further, when the engine 11 is operated at a high load and the cooling water temperature rises to the temperature B, the melting of the melt W2 is started. Since the melt W2 is composed of a single component, it melts quickly when the cooling water temperature reaches the temperature B. For this reason, at this time, the flow rate of the cooling water quickly increases, and the cooling effect of the cooling water by the radiator 12 is also quickly increased.

As described above, according to the thermostat of the first embodiment, the following effects can be obtained. (1) A melt W1 and a melt W2 having a higher melting point than the melt W1 are applied.
In particular, a single-component melt is used as the melt W2. For this reason, when the cooling water temperature is low, the inclination of the valve opening amount of the valve body 21a with respect to the cooling water temperature is reduced,
The change in the flow rate of the cooling water with respect to the change in the same temperature can be reduced. On the other hand, when the temperature of the cooling water increases, the slope can be quickly increased, and the flow rate of the cooling water can be rapidly increased. .

(2) Further, as shown in FIG. 3, when the temperature of the cooling water is increased, the inclination is increased so that, for example, a thermostat (line L4) composed of one kind of melt is used. In comparison, while maintaining the inclination ΔX when the cooling water temperature is low,
The temperature A at which a is opened can be set high, and the warm-up performance of the engine 11 can be improved. Therefore, the time during which the engine 11 is operated in a state where the engine resistance is large can be shortened, and the fuel efficiency can be improved.

(3) As the melt W1, a melt whose melting point temperature A is a temperature at which vaporization of fuel supplied to the engine 11 is promoted is used. The cooling water temperature can be quickly raised to a temperature at which the vaporization of the fuel supplied to the fuel cell can be promoted.

(4) As the melt W2, the melt whose melting point, temperature B, is the transition temperature to the high load operation state of the engine 11 is used. , The valve opening amount of the valve body 21a can be quickly increased, and the cooling effect of the cooling water by the radiator 12 can be promptly increased.

(5) Further, the wax case 21 is formed by the partition 28 so as to form two cases R1 and R2, and the cases R1 and R2 are both in contact with the cooling water. Also, the temperature characteristics of the above-mentioned melts W1, W2 with respect to the cooling water temperature can be easily set. In other words, it is possible to easily obtain desired characteristics as a thermostat while suitably suppressing the hunting of the cooling water temperature and improving the fuel efficiency of the engine.

[Second Embodiment] Hereinafter, a second embodiment of the thermostat according to the present invention will be described with reference to FIGS.
This will be described with reference to FIG. In FIG. 5, the same elements as those in the first embodiment illustrated in FIG. 1 are denoted by the same reference numerals, and a duplicate description of those common elements will be omitted.

First, with reference to FIG. 4, the configuration of a cooling water channel to which the thermostat of the present embodiment is applied will be described.
As shown in FIG. 4, this cooling water passage is
And a passage 51 for supplying cooling water to the radiator 32 from the engine 31, and cooling water cooled by the radiator 32 to the engine 31.
A cooling water supplied from the passages 52 and 53; a bypass passage 53 for returning cooling water branched from the passage 51 and not passing through the radiator 32 to the engine 31; Either one of them is selected, or both cooling waters are mixed, and the cooling water is returned to the engine 31 by a passage 54. Further, the engine 31 is provided with a water pump 33 for forcibly recirculating the cooling water in the cooling passage to the engine 31 through the passage 54. The thermostat 40 of the present embodiment is provided at the intersection of the passage 52 and the bypass passage 53.

Next, the structure and arrangement of the thermostat 40 will be described in detail with reference to FIG. As shown in FIG. 5, a rod 41 projects from the wax case 21 of the thermostat 40 in the direction in which the valve element 21a opens. And, for example, a valve body 41a formed in a disc shape and having a hole formed in the center thereof is disposed so that the rod 41 is inserted into the hole, and the valve body 41a has a distal end from the base end of the rod 41. It is arranged so that it can slide near the part. Further, a spring 42 is provided between the valve body 41a and the wax case 21. That is, the valve body 41
a is urged toward the tip of the rod 41 and disposed.

The thermostat 40 is disposed so that the communication between the passage 52 and the passage 54 is closed by the valve 21a. As described above, the valve 21a is opened when the temperature of the cooling water reaches the temperature A, which is the melting point of the melt W1, and the temperature becomes the temperature B, which is the melting point of the melt W2. After that, the opening is quickly opened fully.

The thermostat 40 is disposed at the intersection of the bypass passage 53 and the passage 54 so that the communicating portion 53a of each of the passages 53, 54 can be closed by the valve body 41a. I have. That is, the valve body 41a is arranged such that when the cooling water temperature is lower than the temperature A, the communication portion 53a is fully opened, and when the temperature reaches the temperature B, the communication portion 53a is closed. Thus, these two valve bodies 21a, 41a
The valve opening amounts change in opposite directions.

The operation of the thermostat 40 having the above-described structure according to a change in the temperature of the cooling water will be described with reference to FIGS. FIG. 6A shows the relationship between the cooling water temperature and the valve opening amount of the valve body 21a.
(B) shows the relationship between the cooling water temperature and the valve opening amount of the valve body 41a. FIG. 7A shows the cooling water flow when the cooling water temperature is lower than the temperature A. FIG. 7B shows the cooling water temperature when the cooling water temperature is higher than the same temperature A but lower than the temperature B. FIG. 7C shows the flow of the cooling water when the temperature of the cooling water is equal to or higher than the same temperature B.

First, when the cooling water temperature is lower than the temperature A which is the melting point of the melt W1, the two melts W1, W2
Does not melt. For this reason, as shown in FIG. 6A, at this time, the valve element 21a is not opened (valve opening amount = 0). On the other hand, as shown in FIG. The body 41a is fully opened. That is, FIG.
At this time, only the cooling water that does not pass through the radiator 32 is returned to the engine 31 through the bypass passage 53 at this time. Therefore, the temperature of the cooling water quickly rises to a temperature at which the vaporization of the fuel supplied to the engine 11 can be promoted, and the warm-up performance of the engine 11 improves.

When the cooling water temperature rises to the temperature A, melting of the melt W1 is started, and the volume of the melt W1 expands. For this reason, as shown in FIG. 6A, the valve opening amount of the valve body 21a gradually increases as the cooling water temperature increases, while as shown in FIG. Accordingly, the valve opening amount of the valve body 41a gradually decreases. That is, as shown in FIG. 7B, at this time, the cooling water after passing through the radiator 32 and the cooling water not passing through the radiator 32 are respectively metered and mixed, and are returned to the engine 31 through the passage 54. Will be done. At this time, both valve bodies 2
Since the valve opening amounts of 1a and 41a are controlled in accordance with the change in the volume of the melt W1, the occurrence of hunting in the cooling water temperature is suppressed.

Further, when the engine 31 is operated under a high load and the temperature of the cooling water rises to the temperature B, melting of the melt W2 composed of a single component is started and the volume of the melt W2 is expanded. Become. For this reason, as shown in FIG. 6 (a), at this time, the valve body 21a is quickly fully opened, while as shown in FIG. 6 (b), the valve body 41a is opened.
Is fully closed. That is, as shown in FIG.
At this time, only the cooling water having passed through the radiator 32 and cooled is returned to the engine 31 through the passage 54, and the cooling efficiency is quickly increased.

As described above, according to the thermostat of the second embodiment, the following effects can be obtained. (1) A melt W1 and a melt W2 having a higher melting point than the melt W1 are applied.
In particular, a single-component melt is used as the melt W2. Therefore, when the temperature of the cooling water is low, the inclination of the valve opening amounts of the two valve bodies 21a and 41a with respect to the temperature can be reduced, and the change of the flow rate of the cooling water with respect to the change of the temperature can be reduced. When the temperature of the cooling water increases, the inclination is increased to rapidly increase the amount of the cooling water that has passed through the radiator 32 and is cooled and returned to the engine 31, and the engine of the cooling water that does not pass through the radiator 32. The amount of reflux to 31 can be reduced quickly.

(2) As shown in FIG. 6 (a), when the temperature of the cooling water is increased, the inclination is increased so that, for example, a thermostat (line) made of one kind of melt is used. L5), the inclination ΔX of the valve opening amount of the valve body 21a when the cooling water temperature is low.
And the temperature (temperature A) at which the valve element 21a is opened can be set high while maintaining the same. Moreover, FIG.
As shown in (b), the temperature (temperature A) at which the valve body 41a starts to close while maintaining the inclination ΔY of the valve opening amount of the valve body 41a when the cooling water temperature is low is kept equal. You can set it higher. Therefore, the time during which the engine 31 is operated in a state where the engine resistance is large can be shortened, and the fuel economy performance can be improved.

(3) As the melt W1, the melt A whose melting point is a temperature at which the vaporization of the fuel supplied to the engine 11 is promoted is used. The temperature of the cooling water can be quickly raised to a temperature at which the vaporization of the fuel supplied to the fuel cell can be promoted.

(4) As the melt W2, the melt whose melting point, temperature B, is the transition temperature to the high load operation state of the engine 11 is used. , Immediately,
The valve opening amount of the valve body 21a is increased, and the valve body 41a
Can be reduced. That is, the cooling effect of the cooling water by the radiator 12 can be promptly increased.

(5) Further, the wax case 21 is formed by the partition 28 so that the inside of the wax case 21 forms two cases R1 and R2, and the cases R1 and R2 are both in contact with the cooling water. Also, the temperature characteristics of the above-mentioned melts W1, W2 with respect to the cooling water temperature can be easily set. In other words, it is possible to easily obtain desired characteristics as a thermostat while suitably suppressing the hunting of the cooling water temperature and improving the fuel efficiency of the engine.

The above embodiments may be modified and implemented as follows. In the above embodiments, the melt W2 is made of a single component, but the melt W2
Any kind of melt may be used as long as the amount of volume change with respect to a change in cooling water temperature is larger than that of the melt W1. Even with such a configuration, it is possible to obtain the same effects as in the above embodiments.

The embodiments of the present invention have been described above. However, it should be added that the embodiments of the present invention include the following various embodiments. (1) A valve provided in a path of cooling water circulating between devices having a temperature gradient, and a valve whose valve opening amount changes according to a change in volume of a melt that melts according to the temperature of the cooling water flows through the path. In the thermostat for controlling the temperature of the cooling water by changing the amount, (a) as the melt, the melting is started at a first temperature, and after the melting is started, the volume changes with the temperature change at a first volume change rate. A first melt that changes, and melting is started at a second temperature higher than the first temperature, and after the start of melting, the temperature is changed to a second volume change rate higher than the first volume change rate. A second melt whose volume changes with the change; and (b) the first and second melts are housed in separate cases.
And (c) each of the cases is arranged so as to be in contact with the cooling water.

In the above configuration, when the temperature of the cooling water becomes higher than the second temperature, the second temperature higher than the first rate of change in volume is used.
With the volume change rate, the valve opening amount changes with the temperature change. That is, the change (gradient) of the valve opening amount of the valve with respect to the cooling water temperature at this time is larger than when the cooling water temperature is lower than the second temperature.

As described above, according to the configuration described in (1), when the cooling water temperature is lower than the second temperature, the inclination can be made relatively small, and the change in the flow rate of the cooling water with respect to the change in the cooling water temperature. Can be made relatively small. On the other hand, when the cooling water temperature becomes higher than the second temperature, the inclination can be increased, and the valve opening amount of the valve can be quickly increased. Moreover, the first temperature at which the valve is opened can be set higher by an amount corresponding to increasing the inclination. Further, since the respective cases accommodating the first melt and the second melt, respectively, are arranged so as to be in contact with the cooling water, setting of the temperature characteristics with respect to the cooling water temperature of the both melts. Also becomes easier. In other words, it is possible to easily obtain desired characteristics as a thermostat while suitably suppressing the hunting of the cooling water temperature and improving the fuel efficiency of the engine.

(2) The equipment having the temperature gradient is a water-cooled engine and a radiator for exchanging heat of cooling water heated by the engine, and a first temperature at which the first melt starts to be melted. Is a temperature at which vaporization of fuel supplied to the engine can be promoted, and a second temperature at which the melting of the second melt is started is a transition temperature to a high-load operation of the engine. The thermostat according to (1).

According to the above configuration, the valve can be prevented from being opened until the temperature of the cooling water reaches a temperature at which the vaporization of the fuel supplied to the engine is promoted. Then, after the valve is opened, the inclination of the valve opening amount with respect to the cooling water temperature during the normal load operation of the engine can be reduced, and the valve opening amount of the valve can be quickly increased during the high load operation of the engine. To prevent overheating of the engine. in this way,
The inclination of the valve opening amount of the valve with respect to the cooling water temperature can be switched according to the operating state of the engine.

(3) The thermostat according to the above (1) or (2), wherein the second melt comprises a single-component wax. Usually, since the melt used for the thermostat is composed of a plurality of components, the inclination of the valve opening amount with respect to the cooling water temperature is such that these components are sequentially melted in accordance with the temperature change of the cooling water. At the predetermined inclination.

In this respect, according to the above configuration, since the wax composed of a single component is applied as the second melt, the wax is melted at once when the cooling water temperature reaches a predetermined temperature. And the valve can be fully opened more quickly.

(4) A first path for circulating cooling water between devices having a temperature gradient and an intersection of the first path and a second path for short-circuiting between the devices are provided. The temperature of the cooling water is controlled by changing the flow rates of the respective paths by two valves whose valve opening amounts change in opposite directions according to the volume change of the melt that melts according to the temperature of the cooling water. In the thermostat, (a) as the melt, a first melt whose melting is started at a first temperature and whose volume changes with a temperature change at a first volume change rate after the melting is started; The melting is started at a second temperature higher than the temperature of the second melt, and after the start of the melting, a second melt whose volume changes with a temperature change at a second volume change rate higher than the first volume change rate; And (b) their first The beauty second melt is accommodated in the other cases, and (c) those that each case arranged therein in a manner that both contact with the cooling water, and wherein the thermostat.

In the above configuration, when the cooling water temperature becomes higher than the second temperature, the second volume higher than the first rate of change in volume is used.
With the volume change rate, the opening amounts of the two valves change with the temperature change. That is, the inclination of the opening amounts of these two valves with respect to the cooling water temperature at this time is larger than when the cooling water temperature is lower than the second temperature.

As described above, according to the configuration described in (4), when the cooling water temperature is lower than the second temperature, the inclination can be made relatively small, and the cooling water is cooled in each of the first path and the second path. The change in the flow rate of the cooling water with respect to the change in the water temperature can be made relatively small. On the other hand, when the cooling water temperature becomes higher than the second temperature, the inclination can be increased, and the flow rate of the cooling water can be increased quickly. In addition, the above 2
The first temperature at which the operation of the two valves is started can be set high. Further, since the respective cases accommodating the first melt and the second melt, respectively, are arranged so as to be in contact with the cooling water, setting of the temperature characteristics with respect to the cooling water temperature of the both melts. Also becomes easier. In other words, it is possible to easily obtain desired characteristics as a thermostat while suitably suppressing the hunting of the cooling water temperature and improving the fuel efficiency of the engine.

(5) The device having the temperature gradient is a water-cooled engine and a radiator for exchanging heat of cooling water heated by the engine, and a first temperature at which the first melt starts to be melted. Is a temperature at which vaporization of fuel supplied to the engine can be promoted, and a second temperature at which melting of the second melt is started is a transition temperature to a high-load operation of the engine, When the temperature of the cooling water is lower than the first temperature, the valve completely closes one of the first paths and fully opens the second path, so that the cooling water only on the engine side is opened. Circulating, and when the temperature of the cooling water is equal to or higher than the first temperature and lower than the second temperature, both the first and second paths are half-open to allow circulation only on the engine side. Between the engine and the radiator When the temperature of the cooling water is equal to or higher than the second temperature, the second path is fully closed and the first path is fully opened, and the engine and the radiator The thermostat according to the above (4), wherein the cooling water is circulated between the thermostats.

According to the above configuration, the first path can be closed until the cooling water temperature rises to a temperature at which vaporization of fuel supplied to the engine is promoted, and the cooling water temperature rises quickly. Can be done. On the other hand, during normal load operation of the engine after the valve is opened, the inclination of the valve opening amount with respect to the coolant temperature can be reduced, and hunting of the coolant temperature can be suppressed. On the other hand, during high-load operation of the engine, the first path can be closed immediately and the second path can be fully opened, so that overheating of the engine can be prevented. Thus, the inclination of the valve opening amount of each valve with respect to the cooling water temperature can be switched according to the operating state of the engine.

(6) The thermostat according to the above (4) or (5), wherein the second melt comprises a single-component wax. According to the above configuration, since a wax composed of a single component is applied as the second melt, the cooling water can be melted at once when the cooling water temperature reaches a predetermined temperature, and the first water can be melted more quickly. Can be closed, and the second path can be fully opened.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the internal structure of a first embodiment of a thermostat according to the present invention.

FIG. 2 is a graph showing the relationship between the temperature of cooling water and the rate of change in volume of a melt.

FIG. 3 is a graph showing a relationship between a temperature of cooling water and a valve opening amount of a valve body.

FIG. 4 is a schematic view showing a configuration of a cooling water passage to be provided in a second embodiment of the thermostat according to the present invention.

FIG. 5 is a schematic diagram showing an internal structure and an arrangement mode of the thermostat according to the second embodiment.

FIG. 6 is a graph showing a relationship between cooling water temperature and valve opening amounts of two valve bodies.

FIG. 7 is a schematic diagram showing a flow of cooling water in a cooling water passage.

FIG. 8 is a schematic diagram showing a configuration of a cooling water channel to be provided in a conventional thermostat.

FIG. 9 is a sectional view showing the internal structure of a conventional thermostat.

[Explanation of symbols]

W1, W2: melt, R1, R2: case, 11: engine, 12: radiator, 20: thermostat, 21
... wax case, 21a ... valve element, 22 ... guide, 23
... Rod case, 25 ... Rod, 26 ... Bracket, 2
6a: Valve seat, 26b: Seal member, 26c: Bracket, 27: Spring, 28: Partition, 31: Engine, 32
... radiator, 33 ... water pump, 40 ... thermostat, 41 ... rod, 41a ... valve element, 42 ... spring, 5
1, 52: passage, 53: bypass passage, 53a: communicating portion, 54: passage.

Claims (3)

[Claims] 1. A thermostat in which first and second melts are separately stored, wherein the melt is started at a first temperature and has a first volume change rate after the start of melting. A first melt whose volume changes with the change, and a second volume whose melting is started at a second temperature higher than the first temperature and higher than the first volume change rate after the melting is started. A second melt whose volume changes with a temperature change at a rate of change. 2. The method according to claim 1, wherein the first melt starts melting.
Is the temperature at which the vaporization of the fuel supplied to the engine can be promoted, and the second temperature at which the melting of the second melt is started is the transition temperature to the high-load operation of the engine. The thermostat according to claim 1. 3. The thermostat according to claim 1, wherein said second melt comprises a single-component wax.