JP2019183747A - thermostat - Google Patents

Abstract

To provide a thermostat which inhibits variations in responsiveness.SOLUTION: A thermostat includes: a housing having a first opening into which a coolant flows from an engine via a radiator, a second opening into which the coolant flows from the engine without going through the radiator, and a third opening which discharges the coolant to the engine; a temperature sensitive part which is displaced according to a temperature of the coolant and housed in the housing; a valve which opens or closes the first opening by displacement of the temperature sensitive part; a coil spring which biases the valve so as to close the first opening; and a shield wall part which is provided at the valve and encloses at least a part of the temperature sensitive part.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a thermostat.

  A thermostat employed in an engine cooling device is known (see, for example, Patent Document 1). The thermostat has a first opening through which cooling water flows from the engine via the radiator, a second opening through which cooling water flows from the engine without passing through the radiator, and a third opening through which the cooling water is discharged to the engine. A housing, a temperature sensing part that is displaced according to the temperature of the cooling water and housed in the housing, a valve that opens and closes the first opening due to the displacement of the temperature sensing part, and a valve that urges the valve to close the first opening A coil spring.

Japanese Patent Laid-Open No. 7-189691

  Since the valve is pressed to close the first opening by the end of the coil spring, in the initial valve opening state where the valve starts to open the first opening, the valve is separated from the position pressed by the end of the coil spring. The valve starts tilting away from the first opening first from the position. For this reason, in the initial valve opening state, the valve opening start position differs depending on the position of the end of the coil spring with respect to the valve. Due to the difference in the valve opening start position, in the initial valve opening state, the mode of mixing of the cooling water introduced into the housing from each of the first and second openings is also different. Variations in the temperature of the cooling water affecting the part also occur. As a result, the valve opening mode may vary, and the thermostat response may vary.

  Therefore, an object is to provide a thermostat in which variation in responsiveness is suppressed.

  The above-described problems include a first opening through which cooling water flows from the engine via a radiator, a second opening through which cooling water flows from the engine without passing through the radiator, and a third opening through which cooling water is discharged to the engine. And a housing that is displaced according to the temperature of the cooling water and that is housed in the housing, a valve that opens and closes the first opening due to the displacement of the temperature sensing portion, and the first opening. This can be solved by a thermostat including a coil spring that biases the valve so as to be closed, and a shielding wall portion that is provided on the valve and surrounds at least a part of the temperature sensing portion.

  A thermostat in which variation in responsiveness is suppressed can be provided.

FIG. 1A is a schematic cross-sectional view of the thermostat of the present embodiment, and FIG. 1B is a schematic view of the thermostat of the present embodiment as viewed from below. FIG. 2 is a schematic cross-sectional view of a thermostat of a comparative example. FIG. 3A is an explanatory diagram of the flow of cooling water in the initial valve opening state of the thermostat of the comparative example when the end portion of the coil spring is at a position of 180 °, and FIG. It is explanatory drawing of the flow of the cooling water in the valve opening initial state of the thermostat of the comparative example in the case of being in the position. FIG. 4A is an explanatory diagram of the flow of cooling water in the initial state of valve opening of the thermostat of this embodiment when the end of the coil spring is at a position of 180 °, and FIG. It is explanatory drawing of the flow of the cooling water in the valve opening initial state of the thermostat of a present Example in the case of a position. FIG. 5 is a graph showing the average temperature of the temperature sensing part according to the position of the end of the coil spring in this example and the comparative example. FIG. 6A is a perspective view of a shielding wall portion that is a first modified example, and FIG. 6B is a perspective view of a shielding wall portion that is a second modified example.

  FIG. 1A is a schematic cross-sectional view of the thermostat 4 of the present embodiment. The thermostat 4 is employed in an engine cooling device, and is specifically arranged on a path through which engine cooling water circulates. The thermostat 4 includes a housing 40, a valve 45 housed in the housing 40, a temperature sensing portion 47, a coil spring 48, and the like. Openings 41, 42, and 43 are formed in the housing 40. A radiator passage 11, a warm-up passage 12, and an engine passage 13 are connected to the openings 41, 42, and 43, respectively. Cooling water discharged from an engine (not shown) via the radiator flows through the radiator passage 11. Cooling water discharged from the engine without passing through the radiator flows through the warm-up passage 12. Note that the cooling water introduced into the housing 40 via the warm-up passage 12 may be cooling water that is discharged from the engine and passes through a heater for heating in the interior of the vehicle in which the engine is mounted. Cooling water is discharged to the engine passage 13 from the thermostat 4 to the engine. Accordingly, the opening 41 is an example of a first opening through which cooling water flows from the engine via the radiator. The opening 42 is an example of a second opening through which cooling water flows from the engine without passing through the radiator. The opening 43 is an example of a third opening that discharges cooling water to the engine. The cooling water circulates through a predetermined path by a water pump arranged on the cooling water path.

  The function of the thermostat 4 will be briefly described. When the temperature of the cooling water introduced into the thermostat 4 through the warm-up passage 12 is lower than a predetermined threshold value, the thermostat 4 is maintained in a valve-closed state, and the cooling introduced into the thermostat 4 from the warm-up passage 12 Water is again supplied to the engine via the engine passage 13. In this way, when the cooling water is at a relatively low temperature, the cooling water is circulated again to the engine without passing through the radiator, thereby promoting warm-up of the engine. When the temperature of the cooling water introduced into the thermostat 4 via the warm-up passage 12 is higher than a predetermined threshold value, the thermostat 4 is opened, and the temperature is relatively low via the radiator passage 11 via the radiator. The cooling water is introduced into the thermostat 4 together with the relatively high temperature cooling water supplied from the warm-up passage 12 and is discharged from the engine passage 13. Thereby, at least the cooling water that has passed through the radiator is radiated by the radiator, the temperature of the cooling water is lowered, and the engine is cooled.

  The valve 45 is provided so that the opening 41 can be opened and closed. Specifically, the valve 45 closes the opening 41 by sitting on a valve seat 44 provided on the opening 41 side. The temperature sensing unit 47 includes a thermal expansion body (for example, thermowax) that thermally expands and contracts according to the temperature of the cooling water flowing around the temperature sensing unit 47. The valve 45 is disposed at the end of the temperature sensing unit 47 on the opening 41 side, and the valve 45 is separated from the valve seat 44 and opens the opening 41 by thermal expansion of the thermal expansion body of the temperature sensing unit 47. Further, when the temperature sensing portion 47 is thermally contracted, the valve 45 is seated on the valve seat 44 and closes the opening 41.

  The coil spring 48 is disposed around the temperature sensing portion 47 and urges the valve 45 to be seated on the valve seat 44. The holding plate 49 is fixed in the housing 40, holds the end of the temperature sensing portion 47 opposite to the side to which the valve 45 is connected, and holds the coil spring 48 between the valve 45 and the holding plate 49. Yes. Further, a gap is partially secured between the holding plate 49 and the inner peripheral surface of the housing 40, and the cooling water flows through this gap. FIG. 1A shows an end portion 48e of the coil spring 48 that contacts the valve 45. The end 48e contacts the valve 45 and presses the valve 45 toward the valve seat 44 side.

  The bulb 45 is provided with a shielding wall portion 46 that surrounds a part of the temperature sensing portion 47, specifically, an end portion of the temperature sensing portion 47 on the bulb 45 side. The shielding wall 46 is cylindrical. The shielding wall 46 is located inside the coil spring 48. The shielding wall 46 may be formed integrally with the valve 45, or may be formed after being formed as a separate body.

  FIG. 1B is a schematic view of the thermostat 4 of this embodiment as viewed from below. FIG. 1B shows the central axis C of the temperature-sensing unit 47 and the positions of 0 °, 90 °, 180 °, and 270 °, which are the counterclockwise angles of the central axis C. 0 ° is a position in the vicinity of the opening 42, 180 ° is a position in the vicinity of the inner wall surface 42s of the housing 40 facing the opening 42 via the central axis C, and 270 ° is a position in the vicinity of the opening 41. The end 48e of the coil spring 48 is located at 180 °. In FIG. 1A, the radiator passage 11 is shown as extending upward from below, but actually, it extends from the front of the paper of FIG. 1A to the back of the paper and is connected to the lower side of the thermostat 4.

  Next, a comparative example different from the present embodiment will be described. FIG. 2 is a schematic cross-sectional view of a thermostat 4x of a comparative example. Unlike the thermostat 4 of the present embodiment, the thermostat 4x of the comparative example is not provided with the shielding wall portion 46. FIG. 3A is an explanatory diagram of the flow of cooling water in the initial valve opening state of the thermostat 4x of the comparative example when the end portion 48e of the coil spring 48 is at a position of 180 °. In the comparative example 4x, the end portion 48e of the coil spring 48 is at a position of 180 ° as in the thermostat 4 of the present embodiment. Therefore, in the initial valve opening state where the valve 45 starts to open, the 180 ° position of the valve 45 is pressed against the valve seat 44 by the end portion 48e of the coil spring 48, and the valve 45 is opposite to the 180 ° position. The 0 ° position begins to move away from the valve seat 44 first. Thus, at the initial stage of opening the valve 45, the 0 ° position of the valve 45 starts to open first and opens in an oblique state. Therefore, as shown in FIG. 3A, the cooling water from the radiator passage 11 flows into the housing 40 of the thermostat 4 from a position of 0 °. Here, the cooling water from the radiator passage 11 and the cooling water from the warm-up passage 12 merge around the opening 42, and a part of the cooling water from the radiator passage 11 passes through the temperature sensing portion 47 from the opening 42 side. Through the inner wall surface 42s of the housing 40 facing the opening 42. A part of the cooling water that collided with the inner wall surface 42s flows to the engine passage 13 side as it is, but the other swirls along the valve 45 and flows again to the opening 42 side, that is, the 0 ° side, It flows to the engine passage 13 together with the cooling water from 12. As described above, a part of the cooling water from the radiator passage 11 flows from the opening 42 side to the temperature sensing part 47, collides with the inner wall surface 42 s of the housing 40, and may flow toward the temperature sensing part 47 again. is there.

  Here, the cooling water from the warm-up passage 12 is a relatively high-temperature cooling water discharged from the engine as described above, but the cooling water from the radiator passage 11 is a relatively low-temperature cooling water passing through the radiator. It is. Accordingly, when the relatively low-temperature cooling water repeatedly flows around the temperature sensing portion 47 in the initial valve opening state, the thermal expansion body of the temperature sensing portion 47 is thermally contracted, and the valve 45 is returned to the valve seat 44 again. There is a possibility of sitting and closing the valve. In the closed state, the relatively low-temperature cooling water from the radiator passage 11 does not flow around the temperature sensing portion 47, but only the relatively high-temperature cooling water from the warm-up passage 12 flows around the temperature sensing portion 47. For this reason, the thermal expansion body of the temperature sensing unit 47 may thermally expand again, the 0 ° position of the valve 45 may be separated from the valve seat 44, and the valve 45 may be opened again. Thus, in the configuration of the comparative example, so-called hunting, in which the opening and closing of the valve 45 is repeated within a predetermined period, may occur. Due to the occurrence of such hunting, the temperature of the cooling water also fluctuates. For example, the controllability of a device whose operation is controlled based on the temperature of the cooling water may become unstable.

  FIG. 3B is an explanatory diagram of the flow of cooling water in the initial valve opening state of the thermostat 4x of the comparative example when the end portion 48e of the coil spring 48 is at the 0 ° position. In this case, in the initial valve opening state, the valve 45 starts to be separated from the valve seat 44 at a position of 180 ° opposite to the 0 ° position. For this reason, most of the cooling water from the radiator passage 11 flows to the engine passage 13 through the space between the inner wall surface 42 s and the temperature sensing portion 47. Therefore, compared with the case where the end portion 48e of the coil spring 48 shown in FIG. 3A is at a position of 180 °, the relatively low temperature cooling water from the radiator passage 11 is suppressed from flowing around the temperature sensing portion 47. Therefore, the occurrence of the hunting described above is suppressed. However, the temperature of the cooling water flowing around the temperature sensing portion 47 differs depending on whether the end portion 48e of the coil spring 48 is at the 0 ° position or the 180 ° position. In the configuration of the comparative example, Depending on the position of the end portion 48e of the coil spring 48, there is a possibility that the response of opening and closing of the thermostat 4x may vary.

  FIG. 4A is an explanatory diagram of the flow of cooling water in the initial state of valve opening of the thermostat 4 of the present embodiment when the end portion 48e of the coil spring 48 is at a position of 180 °. In the present embodiment, as described above, the shielding wall portion 46 surrounding a part of the temperature sensing portion 47 is provided. For this reason, even if the cooling water from the radiator passage 11 collides with the inner wall surface 42 s of the housing 40, the shielding wall portion 46 is prevented from flowing around the temperature sensing portion 47 and flows toward the engine passage 13 side. Thus, compared with the comparative example shown in FIG. 3A, in this embodiment, the cooling water from the radiator passage 11 is suppressed from affecting the temperature sensing portion 47. For this reason, generation | occurrence | production of the hunting mentioned above can also be suppressed.

  FIG. 4B is an explanatory diagram of the flow of cooling water in the initial valve opening state of the thermostat 4 of the present embodiment when the end portion 48e of the coil spring 48 is at a position of 0 °. Also in this case, in the initial valve opening state, the valve 45 starts to be separated from the valve seat 44 at a position of 180 °, but the cooling water from the radiator passage 11 may flow around the temperature sensing portion 47 by the shielding wall portion 46. It is blocked and flows to the engine passage 13 side. For this reason, in this embodiment, regardless of the position of the end portion 48e of the coil spring 48, variations in the temperature of the cooling water flowing around the temperature sensing portion 47 are suppressed, and variations in the open / close response of the thermostat 4 are suppressed. ing.

  FIG. 5 is a graph showing the average temperature of the temperature sensing part 47 according to the position of the end part 48e of the coil spring 48 in this example and the comparative example. In FIG. 5, the flow rate of the cooling water from the radiator passage 11 is the same, and the flow rate of the cooling water from the warm-up passage 12 is also the same. It is the graph which measured average temperature. In the comparative example, the difference in average temperature of the temperature sensing portion 47 is large depending on the position of the end portion 48e of the coil spring 48, whereas in this embodiment, the temperature sensitivity is independent of the position of the end portion 48e of the coil spring 48. This shows that the difference in the average temperature of the portion 47 is small.

  Next, the shielding wall part 46 is demonstrated. The length of the shielding wall 46 in the axial direction is set such that the flow rate of the cooling water flowing from the warm-up passage 12 to the vicinity of the temperature sensing part 47 can be secured when the valve 45 is in the closed state. If the length of the shielding wall portion 46 in the axial direction is too long, there is a possibility that the thermal expansion and contraction of the temperature sensing portion 47 corresponding to the temperature of the cooling water from the warm-up passage 12 may be hindered. This is because there is a possibility that the pressure loss of the cooling water flowing through the pipe increases. If the axial length of the shielding wall portion 46 is too short, the cooling water from the radiator passage 11 cannot be prevented from flowing around the temperature sensing portion 47, and hunting as in the comparative example described above can be prevented. There is a possibility that variations in the generation and open / close response will occur. Therefore, the axial length of the shielding wall portion 46 is sufficient to ensure the responsiveness of the temperature sensing portion 47 due to the temperature of the cooling water from the warm-up passage 12, to suppress the pressure loss of the cooling water, and to generate hunting. It is desirable to set from the viewpoint of suppressing the variation of the response of the suppression and opening and closing.

  Further, it is desirable that the size of the shielding wall portion 46 in the radial direction is small from the viewpoint of suppressing the pressure loss of the cooling water and preventing the cooling water from the radiator passage 11 from flowing around the temperature sensing portion 47. . However, if the diameter of the shielding wall 46 is too small, the shielding wall 46 may come into contact with the temperature sensing part 47 when the valve 45 is opened or closed. For this reason, it is desirable to appropriately set the diameter of the shielding wall portion 46 from the above viewpoint.

  Next, a modified example of the shielding wall will be described. FIG. 6A is a perspective view of a shielding wall portion 46a which is a first modification. The shielding wall portion 46 a is provided with four ribs 462 projecting radially outward on the outer peripheral portion of the cylindrical body portion 461 at substantially equal angular intervals. The rib 462 extends along the axial direction of the body portion 461. As shown in FIG. 4A, the radiator passage that collides with the inner wall surface 42 s by providing the shielding wall portion 46 a on the valve 45 so that at least two of the four ribs 462 face the inner wall surface 42 s of the housing 40. The cooling water from 11 can be guided to the engine passage 13 side. Moreover, as shown to FIG. 4B, it can suppress that the cooling water from the radiator channel | path 11 flows into the temperature sensing part 47 side.

  FIG. 6B is a perspective view of a blocking wall portion 46b that is a second modification. In the blocking wall portion 46b, a guide groove 462b extending in the axial direction of the body portion 461b is formed on one of the four outer surfaces of the substantially rectangular tubular body portion 461b. The guide groove 462b is formed in a tapered shape whose width gradually decreases from one side to the other side in the axial direction of the body portion 461b. Also by providing the shielding wall portion 46b on the valve 45 so that the body portion 461b faces the inner wall surface 42s of the housing 40, as shown in FIG. 4A, the cooling from the radiator passage 11 that has collided with the inner wall surface 42s. Water can be guided to the engine passage 13 side. Moreover, as shown to FIG. 4B, it can suppress that the cooling water from the radiator channel | path 11 flows into the temperature sensing part 47 side.

  The shielding wall portion is not limited to the above-described cylindrical shape or rectangular tube shape, and may be, for example, an elliptical cylindrical shape, a hexagonal cylindrical shape, or another polygonal cylindrical shape. Also good. Further, the diameter of the tube need not be constant in the axial direction. Moreover, in the said Example and modification, although the temperature sensing part 47 is surrounded over the whole circumferential direction, you may surround only one part. For example, the space between the inner wall surface 42 s and the temperature sensing part 47 may be enclosed, but the wall part between the opening 42 and the temperature sensing part 47 may not be enclosed. In this case, the wall portion may have a shape curved around the temperature sensing portion 47 as viewed from the axial direction of the temperature sensing portion 47, or a U-shape so as to surround a part of the temperature sensing portion 47. Also good.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited thereto, and various modifications of these embodiments are within the scope of the present invention. It is apparent from the above description that various other embodiments are possible within the scope.

4 Thermostat 40 Housing 41 Opening (first opening)
42 Opening (second opening)
43 opening (third opening)
45 Valve 46 Shielding wall part 47 Temperature sensing part 48 Coil spring 48e End part

Claims (1)

A first opening through which cooling water flows from the engine via the radiator; a second opening through which cooling water flows from the engine without passing through the radiator; and a third opening through which the cooling water is discharged to the engine. A housing;
A temperature sensing part that is displaced according to the temperature of the cooling water and is housed in the housing;
A valve that opens and closes the first opening by displacement of the temperature sensing portion;
A coil spring that urges the valve to close the first opening;
A thermostat comprising: a shielding wall portion provided on the valve and surrounding at least a part of the temperature sensing portion.

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