JP7126475B2 - thermo actuator - Google Patents

Description

The present invention relates to a thermoactuator having a heating element capable of heating a thermal expansion body enclosed in a case.

A thermoactuator is a component into which a piston advances when the ambient temperature exceeds a predetermined temperature, and is provided, for example, in a thermostat that constitutes a part of a vehicle engine cooling device. As a conventional technology related to thermostats, there is a technology disclosed in Patent Document 1.

FIG. 7 is a diagram in which FIG. 4 of Patent Literature 1 is horizontally reversed, partially corrected, and the reference numerals are reassigned. The thermostat 100 includes a thermoactuator 101 that opens and closes a valve, a first holding portion 102 that holds a portion of the thermoactuator 101 on the temperature sensing portion 101a side, and a support portion that supports a piston 104 of the thermoactuator 101. and a second holding portion 105 holding the portion on the 101b side. A cooling water flow path 103 is provided in the second holding portion 105 .

When the engine warms up, the temperature of the cooling water flowing through the flow path 103 rises, and the wax 101c (thermal expansion body) enclosed in the temperature sensing portion 101a expands. When the wax 101c expands, the piston 104 advances from the support portion 101b to open the valve. Cooling water flows to the radiator and is cooled by a cooling fan. The cooled cooling water cools the engine.

Further, the thermostat 100 is provided with a heater 106 (heating body) capable of forcibly heating the temperature sensing portion 101a. Therefore, even if the temperature of the cooling water is low, the thermoactuator 101 can be operated by heating the temperature sensing portion 101a with the heater 106. FIG.

JP 2006-274898 A

A biasing member 107 is attached to the support portion 101 b of the thermoactuator 101 . Thermoactuator 101 is biased toward heater 106 . Therefore, the temperature sensing portion 101a is in close contact with the heater 106, and the heat transfer efficiency from the heater 106 to the wax 101c is enhanced. The responsiveness of the thermoactuator 101 is improved.

Part of the heat generated by the heater 106 escapes to the cooling water flowing through the flow path 103 via the first holding portion 102 . Therefore, it is necessary to consider the amount of heat that escapes to the cooling water when determining the amount of heat required to heat the wax 101c. In this case, the power consumption of the heater 106 also increases. Therefore, it is conceivable that the heater 106 is incorporated in the temperature sensing portion 101a and the wax 101c is directly heated by the heater 106. FIG. However, simply incorporating the heater 106 limits the improvement in responsiveness, and improvement is desirable.

An object of the present invention is to provide a technique for improving the responsiveness of a heater to heat in a thermoactuator incorporating a heater.

According to claim 1, a cylindrical case, a thermal expansion body that is enclosed in the case and expands and contracts according to the ambient temperature, a piston part of which is housed in the case, and a piston built in the case and a heating body capable of forcibly heating the thermal expansion body,
In a thermo-actuator in which the piston advances and retreats with respect to the case according to expansion and contraction of the thermal expansion body,
The heating body has a cylindrical extension extending in the advancing direction of the piston, and the extension surrounds a portion of the thermal expansion body ,
The extension length of the extension portion is set to a length that can surround at least the rear end portion of the piston when the piston is in the most retracted state,
The outer peripheral surface of the rear end portion of the piston is tapered toward the rear of the piston,
The inner surface of the extending portion includes an enlarged diameter surface that increases in diameter toward the front of the piston, and an inner peripheral surface that is located on the front side of the piston from the enlarged diameter surface and has a constant diameter. There is provided a thermo-actuator characterized by having:

Preferably , the extending portion has a penetrating portion penetrating the piston in a radial direction.

Preferably , a heat insulating portion is provided between the inner peripheral surface of the case and the outer peripheral surface of the heating element.

In claim 1, the heating body capable of heating the thermal expansion body has a tubular extending portion extending in the advancing direction of the piston. This extension encloses a portion of the thermal expansion body. Therefore, the heating body can locally melt the portion of the thermal expansion body enclosed in the case, which is surrounded by the extending portion. Furthermore, the extension also serves to provide heat insulation between the thermal expansion body surrounded by the extension and the fluid flowing around the case. Therefore, the heat applied to the thermally expansible body surrounded by the extending portion is less likely to escape to the outside. As a result, the responsiveness of the thermoactuator to heat generated by the heating element is improved.

As described above, the extension has a tubular shape. Therefore, by adjusting the length of the extension (dimension in the longitudinal direction of the cylinder), the amount of the thermal expansion body heated by the extension can be changed, and the lift amount of the piston of the thermoactuator can be adjusted. .

In addition , the extension length of the extension portion is set to an extension length capable of surrounding at least the rear end portion of the piston when the piston is in the most retracted state. That is, the rear end of the piston is positioned inside the cylindrical extension when the piston is in the most retracted state. Therefore, the extension can heat not only the area behind the rear end of the piston, but also the annular area on the outer periphery of the rear end. The responsiveness of the thermoactuator is further improved.

In claim 2 , the extending portion has a penetrating portion penetrating in the radial direction of the extending portion. A thermally expansible body surrounded by extensions is more sensitive to the temperature of the fluid. Furthermore, the inside and the outside of the extending portion can be communicated with each other through the through portion. Therefore, the thermal expansion body can flow through the through portion. When the thermal expansion body expands due to the heat of the fluid, the expanded thermal expansion body passes through the penetrating portion and enters the extending portion to push out the piston. With regard to the thermoactuator, both the responsiveness to the heat of the heating element and the responsiveness to the heat of the fluid can be achieved.

In claim 3 , a heat insulating portion is provided between the inner peripheral surface of the case and the outer peripheral surface of the heating element. Therefore, it is possible to suppress the heat generated from the heating element from radiating to the outside through the case. Power consumption of the heater can be reduced.

1 is a perspective view of an exhaust heat recovery device having a heating element according to Example 1. FIG. FIG. 2 is a cross-sectional view of the thermoactuator shown in FIG. 1; FIG. 3(a) is a diagram illustrating a heating element of the thermoactuator shown in FIG. FIG. 3(b) is a perspective view of the heating element shown in FIG. 3(a). FIG. 4A is a diagram illustrating a thermoactuator having a heating element according to Example 2. FIG. FIG. 4(b) is a perspective view of the heating element shown in FIG. 4(a). FIG. 4C is a perspective view of a heating element according to modification 1 of embodiment 2. FIG. FIG. 10 is an operation diagram of Example 2; FIG. 6A is a perspective view of a heating element according to modification 2 of embodiment 2. FIG. 6(b) and 6(c) are cross-sectional views of the thermoactuator having the heating element shown in FIG. 6(a). It is a figure explaining the conventional technical basic composition.

An embodiment of the present invention will be described below with reference to the accompanying drawings. In the drawing, Fr indicates the advancing direction of the piston of the thermoactuator, and Rr indicates the retreating direction of the piston.

<Example 1>
FIG. 1 shows an exhaust heat recovery device 11 having a thermoactuator 10 according to an embodiment. The exhaust heat recovery device 11 includes an introduction portion 12, a heat exchanger 13 that communicates with the introduction portion 12 to exchange heat with exhaust gas and cooling water, and is connected to the introduction portion 12 to bypass the heat exchanger 13. a valve chamber 15 to which the bypass pipe 14 is connected; a connecting pipe 16 connecting the heat exchanger 13 and the valve chamber 15; and a discharge portion 17 through which the exhaust gas that has passed through the bypass pipe 14 or the heat exchanger 13 is discharged.

The heat exchanger 13 is connected to an introduction pipe 21 for introducing cooling water and a first pipe 22 for discharging the cooling water that has passed through the heat exchanger 13 . The thermoactuator 10 is connected to a first pipe 22 and a second pipe 23 for discharging cooling water that has passed through the thermoactuator 10 .

A valve (not shown) for opening and closing the end of the bypass pipe 14 is provided in the valve chamber 15 . When the valve is closed, the exhaust gas introduced from the introduction portion 12 passes through the inside of the heat exchanger 13, and heat is exchanged between the exhaust gas and the cooling water. After that, the exhaust gas passes through the valve chamber 15 and is discharged from the discharge portion 17 . When the temperature of the cooling water exceeds a predetermined temperature due to heat exchange, the thermoactuator 10 operates to open the valve. When the valve is open, the exhaust gas passes through the bypass pipe 14 and is discharged from the discharge portion 17 .

As described above, the thermoactuator 10 operates according to the temperature of the cooling water flowing inside the heat exchanger 13, and can be operated by forcibly heating it with a heater, which will be described later.

Please refer to FIG. The thermoactuator 10 includes a cylindrical temperature sensing portion 30 for sensing the ambient temperature, a cylindrical first case half 40 housing the temperature sensing portion 30, and a rod driven by the temperature sensing portion 30. 51 , a biasing member 52 biasing the rod 51 in the backward direction, and a second case half 50 housing the rod 51 and the biasing member 52 .

The temperature sensing part 30 includes a tubular temperature sensing case 60 (case), a wax 31 (thermal expansion body) enclosed in a tubular part 61 of the temperature sensing case 60, and a heater built in the temperature sensing case 60. 70 (heating body), a piston 32 that can move forward and backward with respect to the temperature sensitive case 60, a sleeve 33 that wraps a portion including the rear end portion 32a of the piston 32, and a support hole 34a for the piston 32 that moves forward and backward. and a lid 34 closing the opening 62 of the temperature-sensitive case 60.

The first case half 40 accommodates a bottom portion 42 provided with an insertion hole 42a through which two power supply cords 41, 41 for supplying power to the heater 70 can be inserted, and a cylindrical portion 61 of the temperature sensitive case 60. It consists of a first tubular portion 43 and a first flange portion 44 with which the flange portion 63 of the temperature sensitive case 60 is in contact.

A sealing member 35 is provided at an end portion 64 a of the outer peripheral surface 64 of the temperature sensitive case 60 . A seal member 36 is provided on the contact surface 63 a of the flange portion 63 of the temperature sensitive case 60 .

The first tubular portion 43 is connected to the first pipe 22 and the second pipe 23 . The first cylindrical portion 43 is provided with a first insertion port 25 into which the first pipe 22 is inserted and a second insertion port 26 into which the second pipe 23 is inserted. .

The second case half 50 includes a second flange portion 53 sandwiching the flange portion 63 of the temperature-sensitive case 60 together with the first flange portion 44, and a second flange portion 53 housing the biasing member 52 and the rod 51. and a second bottom portion 55 provided with a hole 55a through which the rod 51 passes. A bearing portion 81 that supports the rod 51 is provided inside the second bottom portion 55 .

The bearing portion 81 includes a bushing 82 and a fixing portion 83 that fixes the bushing 82 to the second bottom portion 54 of the second case half 50 . The front end 51a of the rod 51 is provided with a hook member 84 for opening and closing the valve. A rear end 51 b of the rod 51 is provided with a stopper 85 that regulates the amount of movement of the rod 51 .

One end 52 a of the biasing member 52 abuts on the stopper 85 . The other end 52b of the biasing member 52 abuts on the fixed portion 83. As shown in FIG. A flexible boot 56 is attached to the outside of the second bottom portion 55 to cover the portion of the rod 51 protruding from the second case half 50 .

The first case half 40 and the second case half 50 are integrated with a fastening structure. Specifically, the first case half 40 and the second case half 50 are fastened with two sets of bolts 45 and nuts 46 . Any method such as welding or crimping may be used to fasten the first case half 40 and the second case half 50 together.

Please refer to FIGS. 3(a) and 3(b). The heater 70 has a columnar body portion 71 and an extension portion 90 extending forward (in the advancing direction of the piston 32) from the peripheral edge portion 72a of the front end surface 72 of the body portion 71. As shown in FIG.

The extending portion 90 has a tubular shape and surrounds part of the wax 31 . The center of the extending portion 90 coincides with the center line CL1 of the piston 32 in the advancing/retreating direction. The diameter of the body portion 71 and the outer diameter of the extension portion 90 are equal. The two power supply cords 41 , 41 extend from the rear end surface 73 of the body portion 71 .

A first annular seal member 65 and a second annular seal member 66 are provided between the temperature sensitive case 60 and the heater 70 .

A boundary 70 a between the body portion 71 and the extension portion 90 is provided with a first annular groove 74 for holding the first seal member 65 .

The first annular groove 74 is composed of two first protrusions 75, 75 that are provided in a convex shape with respect to the outer peripheral surface 70b of the heater 70. As shown in FIG. The two first protrusions 75, 75 are spaced apart from each other in the front-rear direction (advancing and retreating direction of the piston). The first convex portion 75 on the front side is located forward of the front end surface 72 of the main body portion 71 .

A rear end 71 a of the body portion 71 is provided with a second annular groove 76 for holding the second seal member 66 .

The second annular groove 76 is composed of two second protrusions 77 , 77 that protrude from the outer peripheral surface 70 b of the heater 70 . The two second protrusions 77, 77 are spaced apart from each other in the front-rear direction. The second convex portion 77 on the rear side has a surface on the same plane as the rear end surface 73 of the main body portion 71 .

The sealing members 65 and 66 are in close contact with the inner peripheral surface 60 a of the temperature-sensitive case 60 when the heater 70 is fitted to the temperature-sensitive case 60 . Between the inner peripheral surface 60a of the temperature sensitive case 60 and the outer peripheral surface 70b of the heater 70, a gap C (insulating portion) is provided.

An inner surface 91 of the extending portion 90 has an enlarged diameter surface 92 that increases in diameter toward the front of the piston 32 and an inner peripheral surface 93 with a constant diameter.

A region of the temperature-sensitive case 60 in front of the front end face 72 of the heater 70 is filled with wax 31 . Wax 31 is filled in a region between the region surrounded by the cylindrical extension 90 and the inner peripheral surface 60 a of the temperature sensitive case 60 and the outer peripheral surface 94 of the extension 90 .

The rear end portion 32a of the piston 32 is positioned inside the cylindrical extension portion 90 when the piston 32 is in the most retracted state. That is, the extension length of the extension portion 90 is set to a length that can surround the rear end portion 32a of the piston 32, and the rear end portion 32a of the piston 32 extends along the inner circumference of the extension portion 90. Surrounded by surface 93 .

<Example 2>
FIG. 4(a) shows part of a thermoactuator 10A having a heater 70A according to the second embodiment shown in FIG. 4(b). Configurations common to the thermoactuator 10 of the first embodiment are denoted by the same reference numerals as in the first embodiment, and descriptions thereof are omitted.

The extension length of the extension portion 90A of the heater 70A according to the second embodiment is longer than that of the extension portion 90 (see FIG. 3B) of the heater 70 according to the first embodiment. A front end 90Aa of the extension 90A is located at the same position as the contact surface 63a of the flange 63 of the temperature-sensitive case 60. As shown in FIG.

Further, the extending portion 90A has a plurality of slits 95 (through portions) extending rearward from the front end 90Aa. The plurality of slits 95 are formed at regular intervals in the circumferential direction.

FIG. 4C shows a heater 70B according to modification 1 of embodiment 2. FIG. The extending portion 90B of the heater 70B has a plurality of through holes 96 (through portions) intermittently formed in the circumferential direction. The through holes 96 are circumferentially spaced at regular intervals and adjacent to each other in the front-rear direction (forward and backward direction).

Next, the effects of the embodiment will be described.

FIG. 5 shows part of the thermoactuator 10A of the second embodiment. A heater 70A capable of heating the wax 31 has a body portion 71 and an extension portion 90A extending forward of the piston 32 from a front end surface 72 (see FIG. 3) of the body portion 71. As shown in FIG. The extending portion 90A has a tubular shape and surrounds a portion of the wax 31. As shown in FIG. Therefore, the heater 70A can locally melt the portion of the wax 31 enclosed in the temperature-sensitive case 60 that is surrounded by the extending portion 90A. Further, the extension 90A also serves to insulate between the wax 31 surrounded by the extension 90A and the fluid flowing around the temperature sensitive case 60. As shown in FIG. Therefore, the heat applied to the wax 31 surrounded by the extending portion 90A is less likely to escape to the outside. As a result, the responsiveness of the thermoactuator 10A to the heat generated by the heater 70A is improved.

As described above, the extending portion 90A has a tubular shape. Therefore, the amount of wax 31 heated by the extension portion 90A can be changed by adjusting the length of extension (dimension in the longitudinal direction of the cylinder), and the amount of lift of the piston 32 of the thermoactuator 10A can be adjusted. becomes.

In addition, the extending portion 90A is set to have an extending length capable of surrounding at least the rear end portion 32a of the piston 32 when the piston 32 is in the most retracted state. Therefore, the extending portion 90 can heat not only the region A1 on the rear side of the rear end portion 32a of the piston 32, but also the annular region A2 on the outer circumference of the rear end portion 32a. The responsiveness of the thermoactuator 10A is further improved. It should be noted that the effect of the second embodiment described above is exhibited also in the first embodiment.

Please refer to FIGS. 4(b) and 5. FIG. In addition, the extending portion 90A of Example 2 has a plurality of slits 95 extending rearward from the front end 90Aa. The depth D of the slit 95 is set to be equal to the penetration depth I of the piston 32 with respect to the extension 90A (including the thickness of the sleeve 33 that wraps the piston 32) when the piston 32 is in the most retracted state. there is Therefore, as indicated by arrow (1), the heat of the cooling water flowing outside the temperature-sensitive case 60 is easily transmitted to the wax 31 within the area surrounded by the extension 90A. The wax 31 can easily sense the temperature of the cooling water.

Further, the area surrounded by the extending portion 90A and the outside can communicate with each other through the slit 95. As shown in FIG. Therefore, the wax 31 can pass through the slit 95 and flow. When the wax 31 expands due to the heat of the cooling water, the expanded wax 31 passes through the slit 95 and enters the extending portion 90A to push the piston 31 out. Even when the wax 31 is surrounded by the extending portion 90, the thermoactuator 10A can achieve both the responsiveness to the heat of the heater 70A and the responsiveness to the heat of the cooling water.

Refer to FIG. 4(c). A heater 70B having a through hole 96 has a similar effect. The through hole 96 is desirably provided so as to surround the piston 32 (see FIG. 5) that enters the extension 90B.

Please refer to FIG. In addition, a gap C is provided between the inner peripheral surface 60a of the temperature sensitive case 60 and the outer peripheral surface 70b of the heater 70A. This gap C serves as a heat insulating layer, and can suppress the heat generated by the body portion 71 from being radiated to the outside through the temperature-sensitive case 60, so that the heat can be transmitted from the heater 70A to the wax 31 without waste. Furthermore, power consumption of the heater 70A can also be reduced. A heat insulating material may be provided in the gap C.

It should be noted that the surface of the heater 70A has a structure that is electrically cut off from the power supply circuit. Therefore, by mixing metal powder into the wax 31, the thermal conductivity of the wax 31 is enhanced, and the responsiveness of the thermoactuator 10A to both the heater 70A and cooling water can be enhanced. The heater 70A becomes capable of self-temperature control by increasing the internal resistance as the temperature rises. Therefore, thermal decomposition of the wax 31 can be prevented.

Modification 2 of Embodiment 2 will be described. Please refer to FIG. The extending portion 90C of the heater 70C has a first notch portion 97 and a second notch portion 98 wider in the circumferential direction than the slit 95 (see FIG. 4B).

Please refer to FIGS. 6(b) and 6(c). The first cutout portion 97 and the second cutout portion 98 are circumferentially shifted from each other by 180 degrees. An orthogonal line C2 perpendicular to the center line C1 passes through the first notch 97 and the second notch 98, and also passes through the first insertion port 25C and the second insertion hole 26C. is doing.

It should be noted that the present invention is not limited to the Examples as long as the action and effect of the present invention are exhibited. For example, when the thermoactuator is used in a sleeve-type thermostat, it is preferable that the sleeve has a small rubber block volume and a (tapered) shape that follows the shape of the piston in terms of wax amount and operability.

The thermoactuator of the present invention is suitable for an exhaust heat recovery device.

DESCRIPTION OF SYMBOLS 10... Thermo-actuator 25C... 1st insertion port 26C... 2nd insertion port 30... Temperature sensing part 31... Wax (thermal expansion body)
Reference Signs List 32 Piston 32a Rear end portion 60 Thermosensitive case 65 Inner peripheral surface 66 First sealing member 67 Second sealing member 70 Heater (heating body) 70b Outer peripheral surface 71 Body portion 74 First annular groove 75 First convex portion 76 Second annular groove 77 Second convex portions 90, 90A, 90B, 90C Extension portion 95 Slit 96 Through hole 97 First Notch portion 98 . . . Second notch portion

Claims (3)

A cylindrical case, a thermal expansion body that is enclosed in the case and expands and contracts according to the ambient temperature, a piston that is partly housed in the case, and a thermal expansion body that is built in the case and forces the thermal expansion body. and a heating element that can be heated physically,
In a thermo-actuator in which the piston advances and retreats with respect to the case according to expansion and contraction of the thermal expansion body,
The heating body has a cylindrical extension extending in the advancing direction of the piston, and the extension surrounds a portion of the thermal expansion body,
The extension length of the extension portion is set to a length that can surround at least the rear end portion of the piston when the piston is in the most retracted state,
The outer peripheral surface of the rear end portion of the piston is tapered toward the rear of the piston,
The inner surface of the extending portion includes an enlarged diameter surface that increases in diameter toward the front of the piston, and an inner peripheral surface that is located on the front side of the piston from the enlarged diameter surface and has a constant diameter. A thermo-actuator comprising: 2. The thermoactuator according to claim 1 , wherein the extending portion has a penetrating portion penetrating in a radial direction of the extending portion. 3. The thermoactuator according to claim 1 , wherein a heat insulating portion is provided between the inner peripheral surface of the case and the outer peripheral surface of the heater.

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