JP2012067850A - Cooling device for internal combustion engine - Google Patents

Abstract

A cooling device for an internal combustion engine that employs a bypass valveless thermostat and improves the working efficiency when the thermostat is assembled to a housing.
In a cooling device for an internal combustion engine, a bypass passage through which cooling water bypassing a radiator from the internal combustion engine flows is formed in a housing. The thermostat 20 drives the valve unit 26 according to the temperature of the cooling water to adjust the circulation amount of the cooling water between the radiator 12 and the internal combustion engine 10, and is displaced when the valve unit 26 is driven. A temperature sensing unit 27 is inserted and an introduction pipe 30 for introducing the cooling water of the bypass passage 13 into the vicinity of the temperature sensing unit 27 is configured. The introduction port 13a of the bypass passage 13 is formed in a manner facing the opening end 31 of the introduction pipe 30, and a gap d1 is formed between the opening end 31 of the introduction pipe 30 and the formation surface of the introduction port 13a. Is done.
[Selection] Figure 1

Description

  The present invention relates to a cooling device for an internal combustion engine that cools the internal combustion engine with cooling water.

  In a cooling device for an internal combustion engine, in order to operate the engine in a temperature environment in which an optimum combustion state can be realized, the internal combustion engine is cooled by cooling water, and the heat of the cooling water thus raised is supplied to the radiator. The temperature of the cooling water is kept at a substantially constant temperature by discharging it to the outside. Also, such a cooling device is usually provided with a thermostat that switches the flow path of the cooling water by opening and closing according to the temperature of the cooling water. For example, when the temperature of the cooling water is still low, such as before the warm-up is completed, the thermostat is closed, so that the cooling water does not flow to the radiator, and the cooling water is cooled via a bypass passage that bypasses the radiator. Water begins to circulate. In the cooling device, the temperature control function of the thermostat can promote the warm-up of the internal combustion engine while avoiding the situation where the internal combustion engine is cooled more than necessary and heat loss increases, so-called overcooling.

  As a typical example of such a cooling device, for example, as described in Patent Document 1, a device provided with a bypass valve thermostat can be cited. As shown in FIG. 7, when the temperature of the cooling water flowing into the housing 140 from the bypass passage 113 and coming into contact with the temperature sensing part 127 rises, the thermostat 120 increases the amount of protrusion of the drive rod 123 to increase the valve. Since the part 126 is displaced downward together with the temperature sensing part 127 in the figure, the thermostat 120 is changed from the valve closed state to the valve opened state. As a result, the cooling water flows from the radiator passage 111 into the pump passage 115, and the cooling water is circulated through the radiator (not shown).

  Further, when the temperature of the cooling water further rises, the valve portion 151 of the bypass valve 150 provided at the lower portion of the temperature sensing portion 127 is seated on the valve seat 152 formed at the opening end portion of the bypass passage 113 and the bypass passage. 113 comes to be closed. Since the bypass valve 150 is closed as described above, the flow rate of the cooling water flowing through the radiator passage 111 is increased. Therefore, the maximum cooling capacity can be increased in the cooling device employing such a bypass valve thermostat.

  By the way, in recent years, while the cooling performance of the radiator has been improved, various attempts have been made to reduce the heat loss of the internal combustion engine. Often not. In other words, in recent cooling devices, when the engine temperature changes with the fluctuation of the engine load, rather than the improvement of the cooling capacity, the radiator flow rate is precisely adjusted with high responsiveness to the change of the engine temperature. Therefore, it is important to avoid the tendency of the internal combustion engine to be overcooled and to reduce its heat loss. In this regard, the bypass valve type thermostat is structurally in contact with the temperature sensing part 127 because the coolant flowing in from the bypass passage 113 must bypass the bypass valve 150 once to contact the temperature sensing part 127. There is a limit to increasing the amount of cooling water to be generated, which becomes a hindrance in increasing the response to engine temperature changes.

  Therefore, instead of the above-described cooling device including the bypass valve type thermostat, a so-called bypass valveless type, in which the bypass valve 150 shown in FIG. 7 is omitted as in the cooling device described in Patent Document 2. A cooling device provided with a thermostat has been proposed.

Hereinafter, an example of a cooling device provided with such a bypass valveless thermostat will be described with reference to FIG.
As shown in FIG. 8, the cooling device is mainly composed of a housing 40 in which various passages through which cooling water flows are formed, and a thermostat 20 that is assembled to the housing 40 in a manner incorporated therein.

  The housing 40 has a radiator passage 11 into which cooling water that has passed through the radiator 12 flows from the internal combustion engine 10, a bypass passage 13 into which cooling water that has bypassed the radiator 12 flows from the internal combustion engine 10, and a suction port of the pump 16. A pump passage 15 for introducing cooling water is formed.

  On the other hand, the thermostat 20 has a valve portion 26 that adjusts the amount of cooling water flowing from the radiator passage 11 to the pump passage 15 based on the opening degree, and a temperature-sensitive drive that opens and closes the valve portion 26 according to the temperature of the cooling water. And a substantially cylindrical introduction pipe 30 into which the temperature sensing unit 27 of the temperature sensing drive unit 300 is inserted.

  In the temperature-sensitive drive unit 300, a thermal expansion material 28 such as paraffin wax is enclosed in a case 27a formed in a bottomed cylindrical shape with a material having high thermal conductivity such as a copper alloy. 1 is provided with a temperature sensing portion 27 having a drive rod 23 that is supported in a manner that one end thereof is immersed and the other end is fixed to the housing 40. The valve portion 26 is fixed to the case 27a of the temperature sensing portion 27 in a manner that closes the opening at the top portion thereof, while a guide rod 27b extending in the direction along the central axis of the case 27a is provided at the bottom portion. It is integrally formed.

  On the other hand, the introduction pipe 30 is communicated with the bypass passage 13 through an introduction port 13 a formed in the housing 40. In addition, the introduction pipe 30 is fixed to the housing 40 in such a manner that the opening end 31 surrounds the entire peripheral edge of the introduction port 13a. Therefore, all the cooling water in the bypass passage 13 is introduced into the introduction pipe 30 through the introduction port 13a. Furthermore, a guide portion having a plurality of flow holes 35 a and a support hole 35 b into which the guide rod 27 b of the temperature sensing portion 27 is inserted and supported is located in the introduction pipe 30 in the vicinity of the opening end portion 31. 35 is formed. In addition, a flange 32 is integrally formed on the outer peripheral surface of the introduction pipe 30, and the flange 32 is fixed to the housing 40 via a support member 24 and the like. A spring 29 that biases the valve portion 26 toward the valve seat 25 fixed to the housing 40 is disposed between the flange 32 and the valve portion 26.

  In the cooling device having such a configuration, the cooling water whose temperature has been increased by cooling the internal combustion engine 10 is introduced into the introduction pipe 30 through the bypass passage 13, the introduction port 13 a, and the flow hole 35 a, and the temperature sensing unit. 27 cases 27a are contacted. Thus, the thermal expansion material 28 enclosed in the inside expands or contracts in accordance with the temperature of the cooling water contacting the case 27a, and tries to change the protruding amount of the drive rod 23 along with the expansion / contraction. A force acts on the drive rod 23.

  That is, when the thermal expansion material 28 expands due to the heat of the cooling water, a force that increases the amount of protrusion acts on the drive rod 23 from the thermal expansion material 28. On the other hand, when the temperature of the cooling water is lowered under such a condition that the thermal expansion material 28 is expanded by the heat of the cooling water, the amount of protrusion of the driving rod 23 via the spring 29 is reduced. Force acts. That is, the protruding amount of the drive rod 23 changes so that the force generated with the expansion and contraction of the thermal expansion material 28 and the urging force of the spring 29 are in an equilibrium state.

  When the temperature of the cooling water contacting the case 27a of the temperature sensing unit 27 becomes equal to or higher than the valve opening temperature of the thermostat 20, that is, the temperature at which the thermostat 20 starts to shift from the valve closing state to the valve opening state, the expansion of the thermal expansion material 28 is performed. The force generated with the contraction exceeds the urging force of the spring 29. As a result, the temperature sensing part 27 and the valve part 26 are displaced to the opening end 31 side (lower side in FIG. 8) of the introduction pipe 30, the valve part 26 is separated from the valve seat 25, and the thermostat 20 is opened. Become. Thus, when the thermostat 20 shifts from the closed state to the open state, the cooling water whose temperature has been increased by the heat of the internal combustion engine 10 also flows into the radiator 12 side.

  Further, when the temperature of the cooling water is in a temperature range equal to or higher than the valve opening temperature of the thermostat 20, the gap between the valve portion 26 and the valve seat 25, that is, the opening degree of the thermostat 20 increases as the temperature of the cooling water increases. growing. Accordingly, the amount of cooling water circulating through the radiator 12 increases, and the amount of heat radiation in the radiator 12 increases, so that the cooling water temperature can be quickly lowered to increase the cooling capacity of the cooling device. Become.

  In the cooling device employing such a bypass valveless thermostat, a configuration is adopted in which the introduction pipe 30 is fixed to the housing 40 in such a manner that the opening end 31 of the introduction pipe 30 surrounds the entire peripheral edge of the introduction port 13a. Therefore, the cooling water that has flowed in from the bypass passage 13 can be brought into contact with the temperature sensing unit 27 without detouring. Therefore, it is possible to increase the amount of cooling water that contacts the temperature sensing unit 27 while suppressing pressure loss due to a large change in the flow line of the cooling water. Further, when the engine load changes and the engine temperature changes, the cooling water whose temperature has changed accordingly quickly comes into contact with the temperature sensing unit 27 through the bypass passage 13, so that the change in engine temperature can be prevented. Therefore, the amount of cooling water passing through the radiator 12 can be adjusted with high responsiveness.

JP 2003-193839 A International Publication No. 2007-108273

  By the way, like the cooling device described in Patent Document 2 described above, a configuration is adopted in which the introduction pipe 30 is fixed to the housing 40 in such a manner that the opening end 31 of the introduction pipe 30 surrounds the entire peripheral edge of the introduction port 13a. If this is done, it is possible to increase the amount of cooling water in contact with the temperature sensing portion 27 by introducing all the cooling water in the bypass passage 13 into the introduction pipe 30, which is desirable in increasing the temperature responsiveness of the thermostat 20. I can say that.

  However, if there is a shape error in the thermostat or the housing, such as the inlet pipe or the opening where the opening end of the pipe is fixed, or if there is an assembly error when the thermostat is assembled in the housing, it will be caused by these errors. Thus, the introduction port forming surface of the housing interferes with the opening end of the introduction pipe. For this reason, when the thermostat is assembled to the housing, it is necessary to repeat fine adjustment of the assembled state so that such interference does not occur, which has been an obstacle to improving the efficiency of the work.

  The present invention has been made in view of such circumstances, and an object thereof is a cooling device for an internal combustion engine that employs a bypass valveless thermostat, and is intended to improve work efficiency when the thermostat is assembled to a housing. is there.

In the following, means for achieving the above object and its effects are described.
The invention according to claim 1 is assembled in a housing having a bypass passage into which cooling water that bypasses the radiator from the internal combustion engine flows, and cools between the radiator and the internal combustion engine by driving a valve portion according to the temperature of the cooling water. An introduction pipe for introducing the cooling water of the bypass passage into the vicinity of the temperature sensing part by inserting a temperature sensing part for adjusting the circulation amount of water and the temperature sensing part of the temperature sensing type driving part which is displaced when the valve part is driven. The internal combustion engine is provided with a bypass valveless-type thermostat including an inlet for introducing cooling water to the opening end of the introduction pipe in a manner facing the opening end. The gist of the present invention is that the thermostat is assembled to the housing in a manner having a gap between the opening end of the introduction pipe and the formation surface of the introduction port. That.

  According to the above configuration, even when there is a shape error in the thermostat or the housing, or when there is an assembly error when the thermostat is assembled to the housing, the shape error or the assembly error is detected at the opening end of the introduction pipe. Can be absorbed by the gap between the inlet and the peripheral edge of the inlet, and due to these errors, the opening end of the inlet tube and the inlet inlet peripheral surface of the housing interfere with each other. Can be avoided. As a result, it is possible to improve the working efficiency when the thermostat is assembled to the housing.

  Furthermore, the cooling water flowing out from the inlet of the bypass passage flows into the inlet pipe, and a part of the coolant leaks from the gap between the opening end and the peripheral edge of the inlet. Therefore, the radiator bypasses the radiator from the internal combustion engine and flows into the bypass passage, and the amount of cooling water flowing through the bypass passage toward the thermostat increases by the amount of the leak. As a result, for example, even when the engine temperature changes greatly due to a sudden change in engine load, the flow rate of the cooling water passing through the radiator with high temperature response so as to follow the change in the engine temperature. Can be adjusted. As a result, even if the amount of cooling water in contact with the temperature sensing portion is reduced by providing the gap, it is possible to suppress a decrease in temperature responsiveness of the thermostat caused by it.

  According to a second aspect of the present invention, in the cooling device for an internal combustion engine according to the first aspect, the amount of cooling water flowing out from the introduction port of the bypass passage flows into the introduction pipe as Va, and leaks from the gap. The gist is that the size of the gap is set so that the magnitude relationship of Va> Vb is established, where Vb is the amount to be performed.

  According to the above configuration, the amount of cooling water introduced to the vicinity of the temperature-sensitive driving unit through the introduction pipe can be ensured, and the feeling of the temperature-sensitive driving unit due to the leakage of cooling water from the gap. It becomes possible to suppress a decrease in temperature characteristics.

  According to a third aspect of the present invention, in the cooling device for an internal combustion engine according to the first or second aspect, the housing has a protrusion that protrudes into the opening end of the introduction pipe around the introduction port. The gist is that it is formed.

  According to the above configuration, when the cooling water of the bypass passage is introduced into the inside from the opening end of the introduction pipe through the introduction port, a part of the cooling water bypasses the tip of the protrusion and Leakage occurs from the gap between the opening end and the peripheral edge of the inlet. Since the cooling water flows in such a manner as to bypass the tip portion of the protrusion, the pressure loss when the cooling water flows through the bypass portion increases. By forming such a detour portion of the cooling water, the amount of leakage of the cooling water is limited (limited). As a result, even if the size of the gap between the opening end portion of the introduction pipe and the formation surface of the introduction port facing this differs due to various errors as described above, the cooling is accordingly accompanied. It is possible to suppress a large change in the amount of water leakage.

In particular, as described in claim 4, if such a protrusion is formed on the housing in such a manner as to surround the entire circumference of the introduction port, the above-described effects can be made more remarkable.
According to a fifth aspect of the present invention, in the cooling device for an internal combustion engine according to any one of the second to fourth aspects, the size of the gap is set in a range of 1.5 to 2.5 mm. Is the gist.

  Various specifications of the cooling device for an internal combustion engine vary depending on the specifications of the internal combustion engine, such as the amount of exhaust, but as for the gap between the opening end of the introduction pipe and the formation surface of the introduction opening, By setting in a range of “1.5 to 2.5 mm”, preferably “2 mm”, it is possible to suppress a decrease in temperature sensitive characteristics of the temperature sensitive driving unit.

The schematic diagram which shows the cross-sectional structure when this is a valve closing state about the whole structure of the cooling device of the internal combustion engine concerning the 1st Embodiment of this invention, and the thermostat employ | adopted for the cooling device. Sectional drawing in the AA of FIG. Sectional drawing which shows sectional structure when the thermostat is in a valve opening state. The graph which shows the relationship between a temperature rise amount and exit temperature. Sectional drawing which shows a cross-section when this is in a valve closing state about the thermostat employ | adopted as the cooling device of the internal combustion engine concerning the 2nd Embodiment of this invention. Sectional drawing which shows the cross-sectional structure about the modification of the thermostat employ | adopted as the embodiment. Sectional drawing which shows the cross-sectional structure about the bypass valve type thermostat employ | adopted as the cooling device of the conventional internal combustion engine. The schematic diagram which shows the cross-section of the cooling device of the conventional internal combustion engine, and the bypass valveless type thermostat employ | adopted for this.

(First embodiment)
Hereinafter, a first embodiment of a cooling apparatus for an internal combustion engine according to the present invention will be described with reference to FIGS. In addition, in the cooling device of the present embodiment, the same reference numerals as in FIG. 8 are given to the configuration having the same function as the cooling device including the conventional bypass valveless thermostat illustrated in FIG. The overlapping explanation will be omitted as appropriate.

  First, the configuration of a cooling device for an internal combustion engine will be described with reference to FIGS. As shown in FIG. 1, a thermostat 20 including a temperature sensing unit 27 is built in a housing 40 in which various passages through which cooling water flows are formed. As shown in FIG. 2 which is a cross-sectional view taken along the line AA of FIG. 1, the cooling water of the introduction pipe 30 can be directly contacted with the bottom of the temperature sensing portion 27, as shown in FIG. Thus, even when the temperature sensing unit 27 is displaced downward in the figure, the outer circumferential surface thereof passes through a gap (circulation unit 33) formed between the outer circumferential surface and the inner circumferential surface of the introduction pipe 30. Cooling water can be contacted. In this way, cooling water is introduced through the introduction pipe 30 in the vicinity of the temperature sensing unit 27. Then, when the cooling water comes into contact with the temperature sensing unit 27, heat exchange is performed between the cooling water and the temperature sensing unit 27.

  Further, the heat sensing unit 27 changes the amount of expansion of the thermal expansion material 28 enclosed therein by such heat exchange, and the amount of protrusion of the drive rod 23 changes accordingly. Move up and down. As a result, the valve part 26 fixed to the case 27a of the temperature sensing part 27 and the valve seat 25 come close to each other and the opening of the thermostat 20 changes according to the temperature of the cooling water.

  Further, as shown in FIG. 1, in the cooling device for the internal combustion engine 10 of the present embodiment, the opening area at the opening end 31 of the introduction pipe 30 and the opening area of the introduction port 13a are set to be approximately the same. The thermostat 20 is assembled to the housing 40 in such a manner that a gap d1 is provided between the opening end 31 of the introduction pipe 30 and the formation surface of the introduction port 13a opposed thereto. Of the cooling water flowing out from the inlet 13a of the bypass passage 13, when Va is the amount flowing into the introduction pipe 30 and Vb is the amount leaking from the gap d1 without flowing into the introduction pipe 30, the magnitude of Va> Vb is satisfied. The size of the gap d1 is set so that the relationship is established. In addition, while ensuring the quantity of the cooling water introduce | transduced into the vicinity of the temperature-sensitive drive part 300 through the introductory pipe 30, the temperature-sensitive characteristic of the temperature-sensitive drive part 300 resulting from a leak of cooling water from the said gap | interval d1. In order to suppress the decrease, the gap d1 is desirably set in the range of “1.5 to 2.5 mm”, preferably “2 mm”.

  4 shows the difference between the temperature of the cooling water flowing into the inlet 10a (see FIG. 1) and the temperature of the cooling water flowing out from the outlet 10b (see FIG. 1) in the cooling system (water jacket) of the internal combustion engine 10, that is, A graph showing the relationship between the temperature rise of cooling water due to heat during engine combustion (hereinafter referred to as “temperature rise Δθ”) and the temperature of cooling water flowing out of the cooling system (hereinafter referred to as “outlet temperature θo”) It is. In this graph, the solid line shows the relationship between the temperature rise Δθ and the outlet temperature θo in the present embodiment. Further, the two-dot chain line is obtained when the gap d1 between the opening end portion 31 of the introduction tube 30 and the formation surface of the introduction port 13a facing this is increased so as to increase the size. The same relationship is shown. Furthermore, the alternate long and short dash line indicates the same relationship when the gap d1 is not formed in this embodiment.

  As shown in FIG. 4, the temperature of the cooling water introduced into the pump passage 15 increases as the temperature increase amount Δθ increases, that is, as the amount of heat received by the cooling water from the internal combustion engine 10 increases. Here, in the configuration in which the size of the gap d1 is excessively increased, as shown by a two-dot chain line in FIG. 4, the outlet temperature θo rapidly increases when the temperature increase amount Δθ increases. There is a tendency. This is because when the amount flowing into the introduction pipe 30 from the introduction port 13a is Va and the amount leaking from the gap d1 without flowing into the introduction pipe 30 is Vb, the relationship of Va ≦ Vb is established, and so on. This is because the amount of cooling water introduced into the vicinity of the temperature sensing unit 27 via the introduction pipe 30 is reduced, and the temperature sensing characteristic of the temperature sensing unit 27 is deteriorated. That is, if the temperature sensing characteristic of the temperature sensing unit 27 is reduced in this way, the valve unit 26 cannot be opened to a sufficient degree of opening in a manner adapted to the increase in engine temperature, and the cooling water passing through the radiator passage 11 is not possible. Since the amount of heat is reduced and the heat cannot be sufficiently dissipated, the outlet temperature θo, in other words, the engine temperature is excessively increased.

  On the other hand, in the configuration in which the gap d1 is not formed, the outlet temperature θo does not increase excessively even when the temperature increase amount Δθ increases, and this embodiment shown by a solid line The outlet temperature θo also changes in a lower temperature range than that of the cooling device. That is, the flow rate of the cooling water in the radiator passage 11 as described above does not decrease and the engine temperature does not rise excessively. However, in this configuration, the work efficiency when the thermostat 20 is assembled to the housing 40 due to factors such as the presence of shape errors in the thermostat 20 and the housing 40 is as described above.

  That is, as a characteristic of the cooling device, the function of opening the valve portion 26 with high responsiveness and suppressing an excessive increase in the engine temperature is avoided even when the engine temperature rises while avoiding such a decrease in work efficiency. It would be desirable to have it. In this respect, in the cooling device according to the present embodiment, the gap d1 is formed, and an appropriate amount of cooling water is leaked from the gap d1, so that the internal combustion engine 10 passes through the bypass passage 13 toward the thermostat 20 side. The amount of circulating cooling water increases by this amount of leakage. As a result, for example, even when the engine temperature changes greatly due to a sudden change in engine load, the cooling water passing through the radiator 12 with high temperature responsiveness so as to follow the change in the engine temperature. The flow rate can be adjusted. Thus, even if the amount of cooling water that contacts the temperature sensing unit 27 is reduced by providing the gap d1, it is possible to suppress a decrease in temperature responsiveness of the thermostat 20 due to the amount of cooling water.

In the first embodiment described above, the following effects can be obtained.
(1) Even if there is a shape error in the thermostat 20 or the housing 40, or there is an assembly error when the thermostat 20 is assembled in the housing 40, the shape error or the assembly error is caused by the opening of the introduction tube 30. It can be absorbed by the gap between the end 31 and the peripheral edge of the inlet 13a, and due to these errors, the opening end 31 of the inlet tube 30, the peripheral edge of the inlet 13a of the housing 40, etc. It can be avoided that the formation surface of the inlet 13a at 40 interferes. As a result, the working efficiency when the thermostat 20 is assembled to the housing 40 can be improved.

  Further, the cooling water flowing out from the introduction port 13 a of the bypass passage 13 flows into the introduction pipe 30, while a part thereof does not flow into the introduction pipe 30 and is between the opening end portion 31 and the peripheral portion of the introduction port 13 a. From the gap d1. Accordingly, the amount of cooling water flowing from the internal combustion engine 10 to the thermostat 20 side through the bypass passage 13 increases by this amount of leakage. As a result, for example, even when the engine temperature changes greatly due to a sudden change in engine load, the cooling water passing through the radiator 12 with high temperature responsiveness so as to follow the change in the engine temperature. The flow rate can be adjusted. Thus, even if the amount of cooling water that contacts the temperature sensing unit 27 is reduced by providing the gap d1, it is possible to suppress a decrease in temperature responsiveness of the thermostat 20 due to the amount of cooling water.

  (2) When the amount of cooling water flowing out from the inlet 13a of the bypass passage 13 flows into the introduction pipe 30 is Va, and the amount of leakage from the gap d1 without flowing into the introduction pipe 30 is Vb, Va> Since the gap d1 is set so that the magnitude relationship of Vb is established, the amount of cooling water introduced to the vicinity of the temperature-sensitive drive unit 300 including the thermostat 20 through the introduction pipe 30 can be secured, and the gap d1 Therefore, it is possible to suppress a decrease in temperature sensitive characteristics of the temperature sensitive driving unit 300 due to leakage of cooling water.

(Second Embodiment)
Next, a second embodiment of the internal combustion engine cooling device according to the present invention will be described with reference to FIG. In the above-described first embodiment, the introduction port 13a of the bypass passage 13 is configured to open on the same plane as the surrounding housing 40. On the other hand, in this embodiment, the protrusion 14 which protrudes to the inside of the opening end part 31 of the inlet pipe 30 is formed in the peripheral part of the inlet 13a in the housing 40, and the inlet 13a is introduced. It has a mode of opening inside the open end 31 of the tube 30. This embodiment is different from the first embodiment in that such a protrusion 14 is formed on the housing 40. Therefore, in the following, the cooling device according to the present embodiment will be described focusing on the differences from the first embodiment.

  FIG. 5 is a cross-sectional view showing a cross-sectional structure of the thermostat 20 and the housing 40, which is the internal combustion engine cooling apparatus according to the present embodiment. As shown in FIG. 5, the housing 40 is formed with a cylindrical projection 14 surrounding the introduction port 13a over the entire circumference. And the thermostat 20 is assembled | attached to the housing 40 in the aspect which has the clearance gap d3 between the opening end part 31 of the inlet tube 30, and the formation surface of the inlet 13a facing this. In the first embodiment described above, the opening area at the opening end 31 of the introduction tube 30 and the opening area of the introduction port 13a are set to be approximately the same. However, in this embodiment, the introduction tube 30 is used. The opening area of the introduction port 13a is set to be smaller than the opening area of the opening end portion 31.

  According to such a configuration, the cooling water in the bypass passage 13 flows out from the introduction port 13 a defined by the protrusion 14 and is introduced into the introduction pipe 30. A part of the cooling water introduced into the introduction pipe 30 leaks from the introduction pipe 30 to the outside through the gap d3 so as to bypass the protrusion 14. Here, in the cooling water introduced from the inlet 13a of the bypass passage 13 into the introduction pipe 30, when Va1 is an amount contacting the temperature sensing portion 27 and Vb1 is an amount leaking from the gap d3, Va1> A magnitude relationship of Vb1 is established. In other words, the size of the gap d3 is set so that this relationship is established.

According to the second embodiment described above, the following effects can be obtained in addition to the effects equivalent to the effects (1) and (2) described in the first embodiment.
(3) A part of the cooling water introduced from the bypass passage 13 into the introduction pipe 30 through the introduction port 13a bypasses the tip end portion of the protrusion 14, and is introduced into the opening end 31 of the introduction pipe 30. Leakage occurs from the gap d3 between the periphery of the mouth 13a. Since the cooling water flows in such a manner as to bypass the tip portion of the protrusion 14, the pressure loss when the cooling water flows through the bypass portion increases. By forming such a detour portion of the cooling water, the amount of leakage of the cooling water is limited (limited). As a result, the size of the gap d3 between the opening end portion 31 of the introduction pipe 30 and the formation surface of the introduction port 13a opposite to the opening end 31 is determined by the shape error of the thermostat 20 and the housing 40 and when the thermostat 20 is assembled to the housing 40. Even if it is different due to various errors such as an assembly error, it is possible to suppress a significant change in the leakage amount of the cooling water.

(4) Since the protrusion 14 is formed in the housing 40 in such a manner as to surround the entire circumference of the introduction port 13a, the effect of the above (3) can be made more remarkable.
In addition, each said embodiment can also be implemented with the following forms which changed this suitably.

  In the second embodiment, the opening area of the introduction port 13a is set smaller than the opening area of the opening end 31 of the introduction pipe 30. According to such a configuration, for example, as in the cooling device described in the first embodiment, compared with the case where the opening area at the opening end 31 and the opening area of the introduction port 13a are set to be approximately the same, Since the amount of cooling water flowing out from the introduction port 13a is reduced, there is a concern that the temperature responsiveness of the thermostat 20 is lowered. Therefore, a form in which the shape of the opening end 31 of the introduction pipe 30 is changed to set the opening area of the opening end 31 large may be adopted. For example, as shown in FIG. 6, if the diameter of the introduction tube 30 is increased from the substantially central portion to the opening end portion 31 in the axial direction, the opening area of the introduction port 13a can be set larger.

In the second embodiment, the protrusion 14 has a cylindrical shape. However, the protrusion 14 is not limited to a cylindrical shape, and may have another shape.
In the second embodiment, the protrusion 14 is formed so as to surround the entire inlet port 13a. However, the protrusion 14 is not limited to this, and at least the inlet port 13a is formed. What is necessary is just to be formed in a peripheral part and to protrude in the inside of the inlet tube 30, for example, you may make it form this only in a part among the perimeters of the inlet 13a. According to such a form, the effect according to the effect of the said 1st Embodiment and the effect according to the effect of (3) of the said 2nd Embodiment can be acquired.

  In the first embodiment, of the cooling water flowing out from the inlet 13 a of the bypass passage 13, Va is the amount that flows into the introduction pipe 30, and the amount that leaks from the gap d <b> 1 without flowing into the introduction pipe 30. When Vb is set, the gap d1 is set so that the magnitude relationship of Va> Vb is established. In the second embodiment, of the cooling water introduced from the introduction port 13a of the bypass passage 13 into the introduction pipe 30, the amount of contact with the temperature sensing portion 27 is Va1, and the amount of leakage from the gap d3 is When Vb1 is set, the size of the gap d3 is set so that the magnitude relationship of Va1> Vb1 is established. Even if the gap between the opening end of the introduction pipe and the formation surface of the introduction opening does not satisfy the flow rate relationship of the cooling water exemplified in the first and second embodiments, the first The effect according to the effect (1) of the embodiment and the effect of the second embodiment can be obtained at least.

  In the first embodiment, the size of the gap d1 between the opening end of the introduction tube and the formation surface of the introduction port is in the range of “1.5 to 2.5 mm”, specifically 2 mm. Although it is set, the size can be set to a value outside this range.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 10a ... Inlet, 10b ... Outlet, 11, 111 ... Radiator passage, 12 ... Radiator, 13, 113 ... Bypass passage, 13a ... Inlet, 14 ... Projection, 15, 115 ... Pump passage, 16 ... Pump, 20, 120 ... Thermostat, 23, 123 ... Drive rod, 24 ... Support member, 25, 152 ... Valve seat, 26, 126, 151 ... Valve part, 27, 127 ... Temperature sensing part, 27a ... Case, 27b ... Guide rod, 28 ... thermal expansion material, 29 ... spring, 30 ... introducing pipe, 31 ... open end, 32 ... flange, 33 ... circulation part, 40,140 ... housing, 150 ... bypass valve, 300 ... temperature-sensitive drive Part, d1, d3... Gap.

Claims (5)

A temperature sensing device that is assembled in a housing having a bypass passage through which cooling water that bypasses the radiator from the internal combustion engine flows, and that controls the circulation amount of the cooling water between the radiator and the internal combustion engine by driving the valve portion according to the temperature of the cooling water. A bypass valveless thermostat including a temperature-type drive unit and a temperature-sensing unit of the temperature-sensitive type drive unit that is displaced when the valve unit is driven, and an introduction pipe that introduces cooling water in the bypass passage to the vicinity of the temperature-sensing unit. An internal combustion engine cooling device, wherein the bypass passage is provided with an introduction port for introducing cooling water into an opening end portion of the introduction pipe facing the opening end portion.
The cooling device for an internal combustion engine, wherein the thermostat is assembled to the housing in a manner having a gap between an opening end portion of the introduction pipe and a formation surface of the introduction port. Of the cooling water flowing out from the inlet of the bypass passage, when the amount flowing into the introduction pipe is Va and the amount leaking from the gap is Vb, the gap of the gap is established so that Va> Vb is established. The cooling device for an internal combustion engine according to claim 1, wherein the size is set. The internal combustion engine cooling device according to claim 1 or 2,
The cooling apparatus for an internal combustion engine, wherein the housing is formed with a protrusion protruding inside the opening end of the introduction pipe around the introduction port. The cooling device for an internal combustion engine according to claim 3, wherein the protrusion is formed on the housing so as to surround the entire circumference of the introduction port. The cooling device for an internal combustion engine according to any one of claims 2 to 4, wherein a size of the gap is set in a range of 1.5 to 2.5 mm.

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