Wax thermo-element and method for manufacturing wax thermo-element

Abstract

This invention addresses the problem of providing a small and inexpensive wax thermo-element that can be installed even in a narrow space, and method for manufacturing said wax thermo-element.　The solution to this problem is a wax thermo-element 1 including a housing 2 in which a wax W is sealed, a piston rod 3 that can protrude and retract with respect to the housing 2, and a ring-form rubber packing 4 that is fitted to the piston rod 3 to seal the wax W, wherein: the housing 2 is constituted of a bottomed cylindrical cup 20 in which wax W is sealed, and a disk-form cover 21 that is connected to the cup 20 to resist internal pressure and that supports the packing 4; a recessed groove 24 is formed in the outer peripheral side surface of the cover 21; and the cup 20 and the cover 21 are connected by a side surface caulking 2a that presses the cylindrical side surface of the cup 20 into the recessed groove 24 and caulks the cup therein.

Description

Wax thermoelement and method for manufacturing wax thermoelement

[0001] The present invention relates to a wax thermoelement, and more particularly to a packing-type wax thermoelement in which a cover is joined to a cup by side crimping as a packing-type seal, and a method for manufacturing the same.

[0002] In cooling systems for electric vehicles such as battery electric vehicles (BEVs) and hybrid electric vehicles (HEVs), various devices such as motors, inverters, and batteries are cooled by coolers via a cooling medium. However, cooling systems for such electric vehicles have more cooling points than cooling systems for conventional internal combustion engine (ICE) vehicles, and the cooling circuits are becoming smaller and more complex.

[0003] In addition, electric vehicle cooling systems use motorized valves to switch between cooling circuits to precisely control the temperature of various devices. Control systems have been developed, including multi-port control valves that control multiple circuits with a single valve, and systems that use multiple one-way valves for each circuit. However, it is predicted that wax thermostats will also be used for switching in electric vehicle cooling systems in the future. In this case, wax thermoelements (thermopellets) will also need to be made smaller and less expensive so that they can be installed in tight spaces.

[0004] In the conventional sleeve-type wax thermoelement (wax seal structure) shown in Figure 7, the wax must be covered by a cup (housing) and a sleeve (sealing member). Therefore, when miniaturizing a wax thermoelement, the sleeve must be made smaller and thinner to match the cup and cover that form the housing. However, issues with the sleeve's fixing structure, manufacturing method, and strength make it difficult to reduce the size below a certain level.

[0005] That is, as shown in Figure 7(b), in a conventional sleeve-type thermoelement, the piston rod, which moves relative to the cup and protrudes and retracts, is covered with a rubber sleeve to isolate it from the wax, reducing the risk of wax leakage. However, in a conventional sleeve-type thermoelement, the contact area between the piston and the rubber sleeve is large, resulting in high sliding resistance and a high biasing force when the return spring pushes it back. Furthermore, when the piston is pushed back by an external force (the biasing force of the return spring), the high sliding resistance generated in the sleeve applies a force that pushes down on the sleeve (causing it to fall off). Therefore, the sleeve must be firmly secured between the cup and cover, sandwiching it from above and below. This requires a fixing structure to secure the sleeve, which increases the cover diameter and the pressure-receiving area. This increases the internal pressure within the wax thermoelement and widens the pressure-receiving area, requiring a high bonding strength between the cover and cup.

[0006] Therefore, it was necessary to deform the top of the cup from top to bottom in the axial direction of the cup, which allows the cover and cup to be clamped with great force and held in place with high bonding strength, and then join them by caulking the top surface so that the deformed part of the cup fits over the cover.This required forming a flange to receive the wax thermo-element when caulking, which created the problem of not being able to reduce the size in the radial direction.

[0007] To solve this problem, it has been considered to join the cup and cover by deforming the side of the cup in a lateral direction perpendicular to the axial direction of the cup, rather than deforming it from above downward and then fitting the deformed part of the cup onto the cover to join them by crimping it on the top surface. However, this type of side crimping does not provide the same bonding strength as the above-mentioned top crimping, so there is a risk that the crimped position of the cover will shift if the pressure inside the wax thermo-element housing becomes high.

[0008] Therefore, by changing the wax seal form of the wax thermoelement from a sleeve type with a large pressure-receiving area of ​​the cover (pressure-receiving diameter D3 in Figure 7(b)) to a packing type (shaft seal) with a small pressure-receiving area of ​​the cover (pressure-receiving diameter D2 in Figure 1(b): D2 < D3), it is possible to reduce the pressure received by the cover of the wax thermoelement, reduce the contact area between the piston rod and the rubber material to reduce sliding resistance, and reduce the internal pressure inside the cup (housing) by reducing the biasing force of the spring that returns the piston rod, resulting in a design that can handle the connection strength of the side crimping, and thus solve the problems with the sleeve fixing structure and strength.

[0009] For example, Patent Documents 1 and 2 each disclose a packing-type wax thermo-element in which wax is sealed with a ring-shaped packing made of rubber material.

[0010] However, the conventional packing-type wax thermoelements described in Patent Documents 1 and 2 do not have a packing-type wax seal for the purpose of reducing the size in the radial direction, but have a structure in which a flange is formed on the cup and the cover is placed on the cup flange, and then the cup and cover are joined by plastic deformation from above the cup with a metal blade. In other words, the conventional packing-type wax thermoelements have a flange formed on the wax thermoelement, and therefore cannot be reduced in size in the radial direction.

[0011] Furthermore, wax thermoelements are required to have a constant lift amount at a given temperature when they are manufactured. However, in conventional wax thermoelements, the internal volume of the wax-filled portion varies due to dimensional variations in the sleeve and other components. Therefore, in order to maintain a constant lift amount in wax thermoelements, an indentation process is required after assembly to deform the sides and bottom of the cup to adjust the internal volume of the wax-filled portion, which increases the manufacturing process.

[0012] Patent No. 4293506 JP 2021-131142 A

[0013] The present invention has been devised to solve the above problems, and its object is to provide a small, inexpensive wax thermoelement that can be installed in a small space, and a method for manufacturing the same.

[0014] The wax thermoelement of the first invention is a wax thermoelement comprising a housing filled with wax, a piston rod that can be freely protruded and retracted into the housing, and a gasket made of a ring-shaped rubber material that is fitted onto the piston rod to seal the wax, wherein the housing has a cylindrical cup with a bottom that is filled with the wax, and a disk-shaped cover that is connected to the cup to resist internal pressure and support the gasket, and a groove is formed on the outer side surface of the cover, and the cup and cover are connected by a side crimp in which the cylindrical side surface of the cup is pressed into the groove and crimped.

[0015] The wax thermoelement of the second invention is characterized in that, in the first invention, the cylindrical inner diameter of the cup is approximately the same except for the side crimped portion, and in a cross section along the axis, it is a straight line parallel to the axis, and the cover is positioned relative to the cup according to the internal volume of the wax-enclosed portion of the cup and is joined by the side crimped portion.

[0016] The wax thermoelement of the third invention is characterized in that, in the first invention, the cylindrical inner diameter of the cup is approximately the same as the disk-shaped outer diameter of the cover, excluding the packing portion, and the cover is positioned relative to the cup according to the internal volume of the wax-enclosed portion of the cup and is joined with the side crimps.

[0017] The manufacturing method of a wax thermoelement according to the fourth invention is a manufacturing method of a wax thermoelement that manufactures a wax thermoelement having a housing filled with wax, a piston rod that can be freely protruded and retracted into the housing, and a gasket made of a ring-shaped rubber material that is fitted onto the piston rod and seals the wax, characterized in that the housing is composed of a cylindrical cup with a bottom in which the wax is sealed, and a disk-shaped cover that is connected to the cup to resist internal pressure and support the gasket, and a groove is formed on the outer side of the disk-shaped cover, and after the cover is inserted into the cup, the cylindrical side of the cup is pressed into the groove and plastically deformed, thereby crimping and joining the cover to the cup with a side crimp.

[0018] The manufacturing method of a wax thermoelement according to the fifth invention is characterized in that, in the fourth invention, the processing of forcing the side of the cup into the groove to cause plastic deformation is carried out by crimping, in which a metal blade is pressed against the cup to cause plastic deformation, or by bulging, in which the cup is pressed with the pressure of an elastic body or fluid to cause plastic deformation.

[0019] The method for manufacturing a wax thermoelement according to the sixth invention is characterized in that, in the fourth or fifth invention, the process of forcing the side of the cup into the groove to plastically deform it takes into account the inner diameter of the cup and the volume of the packing, and after adjusting the position of the cover so that the lift amount of the piston rod at a predetermined temperature is a constant value according to the internal volume of the wax-enclosed portion of the cup, crimping is performed.

[0020] According to the first to sixth inventions, by changing the seal configuration from a sleeve type with a large pressure-receiving area of ​​the cover to a packing type (shaft seal) with a small pressure-receiving area of ​​the cover, the pressure received by the cover is reduced, and by reducing the contact area between the piston rod and the rubber material, sliding resistance is reduced. By reducing the biasing force of the spring that returns the piston rod, the internal pressure in the cup (housing) is reduced. Furthermore, because the cup and cover are crimped on the sides rather than the top, there is no need to provide a flange as with a crimped top, and the cup can be made smaller in the radial direction. This allows a wax thermoelement to be installed in a narrow space, and a flow path can be secured to reduce pressure loss.

[0021] In particular, according to the second, third and sixth inventions, the indentation process for adjusting the internal volume of the wax-enclosed portion after assembly is not required, thereby reducing the number of manufacturing steps and reducing manufacturing costs.

[0022] FIG. 1 shows a wax thermoelement according to an embodiment of the present invention, where (a) is a front view perpendicular to the axis, and (b) is a vertical cross-sectional view along the axial direction. FIG. 2 is a perspective view showing the cover of the same thermoelement alone. FIG. 3 is a process explanatory diagram showing the cover position adjustment step in the manufacturing method of a thermoelement according to this embodiment, where (a) shows a case where the inner diameter of the cup 20 is smaller than specified and the weight of the packing 4 is heavier than specified, and (b) shows a case where the inner diameter of the cup 20 is larger than specified and the weight of the packing 4 is lighter than specified. FIG. 4 is a process explanatory diagram showing the side crimping step by crimping the metal blade in the manufacturing method of the same thermoelement, where (a) shows the state before processing and (b) shows the state after processing. FIG. 5 is a process explanatory diagram showing the side crimping step by bulge processing in the manufacturing method of a thermoelement according to this embodiment, where (a) shows the state before processing and (b) shows the state after processing. FIG. 6(a) is a vertical cross-sectional view along the axial direction of a wax thermoelement 1′ according to Modification 1, and FIG. 6(b) is a vertical cross-sectional view along the axial direction of a wax thermoelement 1″ according to Modification 2. FIG. 7 is a diagram showing a conventional sleeve-type wax thermoelement, where (a) is a front view seen in a direction perpendicular to the axis, and (b) is a vertical cross-sectional view along the axial direction.

[0023] A wax thermoelement according to an embodiment of the present invention will be described in detail below with reference to the drawings.

[0024] <Configuration of wax thermoelement> The configuration of a wax thermoelement 1 according to an embodiment of the present invention will be described using Figures 1 and 2. Figure 1 shows a wax thermoelement 1 according to an embodiment of the present invention, where (a) is a front view seen in a direction perpendicular to the axis, (b) is a vertical cross-sectional view along the axial direction, and Figure 2 is a perspective view showing the cover 21 of the thermoelement 1 alone.

[0025] As shown in FIG. 1, a wax thermoelement 1 (hereinafter simply referred to as thermoelement 1) according to an embodiment of the present invention is a packing-type wax thermoelement comprising a housing 2 in which wax W such as paraffin wax is enclosed, a piston rod 3 that can be freely protruded and retracted into the housing 2, and a packing 4 that is fitted onto the piston rod 3 to seal in the wax W.

[0026] This thermo-element 1 is designed so that as the ambient temperature rises, the wax W inside the housing 2 expands, causing the piston rod 3 to protrude. Of course, the wax enclosed in the housing 2 is not limited to paraffin wax, and any substance that has predetermined thermal expansion characteristics with a relatively large volume change, such as microwax, can be applied to the present invention.

[0027] (Housing) The housing 2 is a container that encloses the wax W and functions as a housing for the entire thermo-element 1. The housing 2 is a metal container that has a predetermined strength that can withstand the expansion pressure of the wax W at high temperatures, and the housing 2 in this embodiment is made of stainless steel (SUS430).

[0028] The housing 2 is composed of a cylindrical cup 20 with a bottom filled with wax W, a disk-shaped cover 21 coupled to the cup 20 to resist internal pressure, and the cup 20 and the cover 21 are coupled by caulking.

[0029] (Cup) As shown in Figure 1(a), the cup 20 according to this embodiment has a cylindrical outer diameter set to D1, and has approximately the same diameter from top to bottom except for the side crimp 2a portion, which will be described in detail later. In other words, as shown in Figure 1(a), the cup 20 has a straight cylindrical shape in which the outer diameter of the cup upper part 22, which is the portion above the side crimp 2a, and the outer diameter of the cup lower part 23, which is the portion below the side crimp 2a, both have D1, i.e., a linear shape parallel to the axis of the cup 20. The outer diameter D1 of the cup 20 according to this embodiment is set to 7 mm.

[0030] 1(b), the inner diameter D2 of the cup 20 according to this embodiment is also substantially the same diameter as the outer diameter of the disk-shaped cover 21, which is straight from top to bottom except for the side crimped portion 2a. Therefore, before being crimped and joined, the cover 21 is slidable relative to the cup 20, and as will be described later, the position of the cover 21 relative to the cup 20 can be easily adjusted according to the internal volume of the wax-enclosed portion of the cup 20, and then joined by side crimping.

[0031] Here, "approximately the same diameter corresponding to the outer diameter of the straight, disc-shaped cover 21 from top to bottom, excluding the side crimped portion 2a," refers to a wax thermoelement 1' according to Modification 1 shown in Figure 6(a) that has a uniform inner diameter and a tapered outer surface that gradually thickens, or a wax thermoelement 1' according to Modification 1 that has a stepped outer diameter (not shown). Even in such cases, the cover 21 is slidable relative to the cup 20, allowing for easy positioning of the cover 21 relative to the cup 20 in accordance with the internal volume of the wax-enclosed portion of the cup 20. Figure 6(a) is a vertical cross-sectional view of the wax thermoelement 1' according to Modification 1, taken along the axial direction. Note that the same reference numerals in the figure as those in the wax thermoelement 1 according to the embodiment of the present invention refer to the same components, and therefore will not be described here.

[0032] Furthermore, as shown in Figure 6(b), the inner diameter D2 of the cup 20 may be substantially the same as the outer diameter of the recessed groove 24, which corresponds to the outer diameter of the disk-shaped cover 21 (described later), except for the two packing portions 2b. Even in this case, if there is play between the two packing portions 2b, 2b, it is easy to fine-tune the internal volume of the wax-enclosed portion by adjusting the position of the side crimps 2a within that range. Figure 6(b) is a vertical cross-sectional view taken along the axial direction of a wax thermoelement 1" according to Modification 2.

[0033] The packing portion 2b refers to the packings 4, 4' described below, and the portions related to the sealing function of the packings 4, 4', such as the backup ring 5 that prevents the packings 4, 4' from entering the gap between the cover 21 and the piston rod 3, and the upper end ring 6 that prevents the intrusion of external liquid.

[0034] 2 and 1(b), the cover 21 is a doughnut-shaped disc-shaped member having a through-hole 21a for inserting the piston rod 3, and a recessed groove 24 is formed on the outer circumferential side surface of the cover 21. In other words, an upper flange 25 and a lower flange 26 are formed corresponding to the inner circumferential diameter of the cup 20, and there is a portion on the side surface between them whose diameter is smaller than the upper flange 25 and the lower flange 26, and this portion forms the recessed groove 24.

[0035] As will be described in detail later, as shown in Figure 1(b), the cup 20 and cover 21 are joined by pressing the cylindrical side of the cup 20 into this groove 24 and using side crimps 2a, with the cover 21 being positioned relative to the cup 20 in accordance with the internal volume of the wax-enclosed portion of the cup 20.

[0036] (Piston rod) The piston rod 3 is made of a stainless steel (SUS304) rod having a predetermined diameter (diameter φ=2.8 mm in the illustrated form), and has the function of protruding from the housing 2 due to the expansion pressure caused by the temperature rise of the wax W sealed inside the housing 2.

[0037] (Packing) The packing 4 is made of a ring-shaped (donut-shaped) rubber material such as fluorinated vinylidene (FKM) rubber, and is fitted in a compressed state to the piston rod 3 under the cover 21 on the wax W side, thereby sealing the wax W. A backup ring 5 made of fluororesin (PTFE: polytetrafluoroethylene) is interposed between the packing 4 and the cover 21. The backup ring 5 prevents the packing 4 from entering the gap between the cover 21 and the piston rod 3 due to the internal pressure of the thermo-element 1.

[0038] The upper end of the cup 20 is fitted with a ring-shaped (doughnut-shaped) packing 4' made of rubber and having the same structure as the packing 4, and a stainless steel upper end ring 6, through which the piston rod 3 passes, is fitted and rolled up to seal. This upper end ring 6 has the function of preventing external liquid flowing outside the thermo-element 1 from entering the thermo-element 1.

[0039] <Method of Manufacturing Thermoelement> Next, a method of manufacturing a wax thermoelement according to an embodiment of the present invention will be described using Figures 3 to 5. The method will be described assuming the case of manufacturing the aforementioned packing-type wax thermoelement 1. Note that the method of manufacturing a wax thermoelement according to an embodiment of the present invention (hereinafter also simply referred to as a thermoelement manufacturing method) differs from conventional methods of manufacturing packing-type wax thermoelements in that it does not include an indentation step and that the method of joining the cup 20 and cover 21 is different from conventional methods. Therefore, these points will be mainly described, and other detailed descriptions will be omitted.

[0040] (Cover Position Adjusting Process) First, in the manufacturing method of a thermoelement according to this embodiment, as shown in Fig. 3, a cover position adjusting process is carried out in which wax W is filled into the cup 20 and the position (height in the illustrated state) of the cover 21 is adjusted with the packings 4, 4', backup ring 5, and cover 21 attached to the piston rod 3. Fig. 3 is a process explanatory diagram showing the cover position adjusting process of the manufacturing method of a thermoelement according to this embodiment, where (a) shows a case where the inner diameter of the cup 20 is smaller than specified and the weight of the packing 4 is heavier than specified, and (b) shows a case where the inner diameter of the cup 20 is larger than specified and the weight of the packing 4 is lighter than specified.

[0041] In the cover position adjustment process, the inner diameter D2 of the cup (see Figure 1 (b)) and the volume of the gasket 4 are taken into consideration, and the position is adjusted so that the lift amount of the piston rod 3 becomes a constant value according to the internal volume of the wax-enclosed portion of the cup 20, and the cover 21 is fixed at a predetermined position that will be the processing position for the next process.

[0042] Here, taking into consideration the inner diameter D2 of the cup 20 and the volume of the packing 4 means that, as shown in Figure 3(a), the volume is estimated by measuring the weight of the packing 4, which has a uniform density.Therefore, if the actual measured value of the inner diameter D2 of the cup 20 is smaller than the normal value D2 (D2', D2' < D2), or / and the weight of the packing 4 is heavier than the normal weight, the internal volume of the wax-enclosed portion will be smaller than the normal value.In such cases, in order to set the internal volume of the wax-enclosed portion to the specified value, the installation position (height) of the cover 21 is set to H1', ​​which is higher than the specified height H1 (H1 < H1').

[0043] Conversely, as shown in FIG. 3(b), if the actual measurement value of the inner diameter D2 of the cup 20 is D2" and D2" is larger than the normal value D2, or / and the weight of the packing 4 is lighter than the normal weight, the internal volume of the wax-enclosing portion will be larger than the normal value. In such cases, in order to set the internal volume of the wax-enclosing portion to the specified value, the installation position (height) of the cover 21 is set to H1" which is lower than the specified height H1 (H1>H1").

[0044] By performing this process and then simply crimping the cup 20 and cover 21 together in the next process, the conventional indent process is no longer necessary, reducing the number of manufacturing steps and the manufacturing cost of the thermoelement 1. In other words, in conventional wax thermoelements, in order to correct variations in the internal volume of the wax-enclosed portion, an indent process is performed after assembly to adjust the internal volume of the wax-enclosed portion by pressing a side recess or the like into the side surface (or sometimes the bottom surface) of the cup. However, by simply performing this cover position adjustment process, it is no longer necessary to perform a processing step that involves errors, such as actually forming a recess, thereby improving production efficiency and reducing the number of manufacturing steps.

[0045] (Side Crimping Step) Next, in the manufacturing method of a thermo-element according to this embodiment, a side crimping step is carried out in which, with the cover positioned in the previous step, the cylindrical side of the cup 20 is pressed into the recessed groove 24 of the cover 21 and plastically deformed to crimp and join the cover 21 to the cup 20. In other words, in the manufacturing method of a thermo-element according to this embodiment, the method of joining the cup 20 and the cover 21 is side crimping rather than the conventional top crimping, as described in the background art. There are at least two specific processing methods for side crimping: crimping using a metal blade and bulge machining.

[0046] <Crimping with a Metal Blade> First, the crimping method using a metal blade will be described with reference to Fig. 4. Fig. 4 is a process explanatory diagram showing the side crimping step by crimping a metal blade in the manufacturing method of a thermo-element according to this embodiment, where (a) shows the state before crimping and (b) shows the state after crimping.

[0047] As shown in Figure 4, in the side crimping process using metal blades, a pair of left and right metal blades C1, C1 corresponding to the shape of the side crimp 2a described above are clamped from both sides and pressed against the side of the cup 20, forcing the side of the cup 20 into the recessed groove 24 of the cover 21 and causing plastic deformation, and the cover 21 is crimped and joined to the cup 20.

[0048] At this time, unlike the top surface crimp with a flange described in the background art, the side crimp 2a plastically deforms the cup 20 from the side, so if the deformation is caused by a force that is greater than expected (excessive deformation), the cover 21 may be deformed, and the piston rod 3 guided by the through hole 21a may malfunction.

[0049] Therefore, in the side crimping process by crimping the metal blade, the cup 20 is deformed, but the range of motion of the metal blade C1 (amount of deformation = amount of crushing) where the cover 21 does not deform is strictly controlled, and the range of motion of the metal blade C1 is limited to a range where the cover 21 does not deform.

[0050] <Bulge Forming> Next, the bulge forming method will be described with reference to Fig. 5. Fig. 5 is a process explanatory diagram showing the side crimping step by bulge forming in the manufacturing method of the thermo-element according to this embodiment, where (a) shows the state before processing and (b) shows the state after processing.

[0051] As shown in Figure 5, in the side crimping process using bulge processing, the thermoelement 1, whose position of the cover 21 has been adjusted and fixed in the cover position adjustment process described above, is set in the bulge processing device 10, and the pressure of the elastic body is used to press the side of the cup 20 into the recessed groove 24 of the cover 21, causing plastic deformation, and the cover 21 is crimped and joined to the cup 20.

[0052] As shown in FIG. 5 , this bulge processing device 10 includes a pair of slidable pressing jigs J1, J1 and a support W1 that receives the pressure of these annular pressing jigs J1, J1. An annular elastic body E1 is interposed between the support W1 and the pressing jig J1. The pressing jig J1 is slid to compress the elastic body E1, and the pressure of the elastic body E1 is directed toward the open side where the support W1 is not present. This sandwiches the thermo-element 1 between the elastic bodies E1 from both sides, and the pressure of the elastic body E1 presses the side of the cup 20 into the recessed groove 24 of the cover 21, causing plastic deformation, and crimping the cover 21 to join the cup 20. The elastic body E1 is not limited to an elastic body, but can also be a fluid such as water or a viscous material. This is because a fluid can transmit pressure in a direction opposite to the direction of pressure, similar to the elastic body E1.

[0053] At this time, similar to the crimping process using a metal blade, the side crimping 2a (see Figure 4) differs from the top crimping with a flange described in the background art in that it plastically deforms the cup 20 from the side. Therefore, if deformation is caused with a force greater than expected (excessive deformation), the cover 21 may be deformed, and the piston rod 3 guided by the through hole 21a may malfunction.

[0054] Therefore, in the side crimping process using bulge processing, the pressure that deforms the cup 20 but does not deform the cover 21 is strictly controlled, and the pressure acting on the elastic body E1 is limited to a range that does not deform the cover 21.

[0055] There is also concern about insufficient strength due to poor crimping (too little deformation) caused by dimensional variations in components during mass production and dimensional fluctuations in the processing machines and jigs, but in the side crimping process using bulge processing, as mentioned above, poor crimping (too little deformation) can be eliminated by strictly controlling the pressure that deforms the cup 20 but does not deform the cover 21.

[0056] According to the thermo-element 1 and its manufacturing method of the present embodiment described above, by changing to a packing type (shaft seal) with a smaller pressure-receiving area, the pressure received by the cover 21 is reduced, and by reducing the contact area between the piston rod 3 and the rubber material compared to the sleeve type, sliding resistance is reduced. Furthermore, by reducing the biasing force of the spring that returns the piston rod 3, the internal pressure within the housing 2 is reduced. Furthermore, since the cup 20 and the cover 21 are joined with the side crimps 2a, there is no need to provide a flange that serves as a support, as opposed to a top crimp, and the outer diameter D1 and inner diameter D2 of the cup 20 can be made into a straight cylindrical outer surface with the same diameter, allowing the cup 20 to be made smaller in the radial direction.

[0057] As shown in Figure 7(a), in the case of a sleeve-type wax thermoelement with a crimped upper surface, the outer diameter of the flange portion of the cup was 11.8 mm, and the outer diameter of the general portion of the cup was 9 mm.

[0058] In contrast, in the thermoelement 1, as shown in Figure 1(a), the outer diameter D1 of the cup 20 is a straight cylinder, and the outer diameters of the cup upper part 22 and the cup lower part 23 are both D1 = 7 mm, which is a reduction of 4.8 mm in the radial direction. This allows the thermoelement 1 to be mounted in a narrow space, and also ensures a flow path to reduce pressure loss.

[0059] 1(b) and 6(a), in the thermoelement 1 and the thermoelement 1' according to the first modification, the inner diameter D2 of the cup 20 is substantially the same diameter as the outer diameter of the disk-shaped cover 21, which is straight from top to bottom except for the side crimped portion 2a. Therefore, before being crimped and joined, the cover 21 is slidable relative to the cup 20, and the position of the cover 21 relative to the cup 20 can be easily adjusted according to the internal volume of the wax-enclosed portion of the cup 20, and then joined by side crimping.

[0060] Furthermore, as shown in FIG. 6(b), the thermo-element 1" according to the second modified example has, with the exception of the two packing portions 2b, a diameter that is substantially the same as the outer diameter of the recessed groove 24 that corresponds to the outer diameter of the disk-shaped cover 21. For this reason, it is easy to fine-tune the internal volume of the wax-enclosed portion by adjusting the position of the side crimp 2a within the range of play between the two packing portions 2b, 2b.

[0061] Furthermore, according to the thermoelement 1 and its manufacturing method, as described above, by simply performing the cover position adjustment process, the indentation process for adjusting the internal volume of the wax-enclosed portion after assembly is no longer necessary, thereby reducing the number of manufacturing steps and reducing manufacturing costs.

[0062] The wax thermoelement 1 and its manufacturing method according to the embodiment of the present invention have been described in detail above. However, the above-described and illustrated embodiments are merely specific examples of the present invention. Therefore, the technical scope of the present invention should not be interpreted as being limited by these embodiments. In particular, the materials and dimensions of each component are merely examples, and it goes without saying that they can be appropriately changed to other materials having equivalent strength.

[0063] It should be noted that the lift amount does not refer to the amount of rise of the piston rod, but rather to the amount (length) of protrusion of the piston rod from the housing, and it goes without saying that the concept is applicable even if the thermoelement 1 is installed upside down or laid sideways compared to the illustrated form.

[0064] 1, 1', 1": Thermoelement (packing-type wax thermoelement) 2: Housing (casing) 2a: Side crimp 2b: Packing part 20: Cup 21: Cover 21a: Through hole 22: Upper part of cup 23: Lower part of cup 24: Groove 25: Upper flange 26: Lower flange 3: Piston rod 4, 4': Packing 5: Backup ring 6: Upper end ring W: Wax C1: Metal blade 10: Bulge processing device J1: Pressing jig W1: Receiving stand E1: Elastic body (fluid)

Claims

1. A wax thermoelement comprising a housing filled with wax, a piston rod that can project and retract with respect to the housing, and a packing made of a ring-shaped rubber material fitted to the piston rod to seal the wax, wherein the housing has a bottomed cylindrical cup filled with the wax, and a disc-shaped cover that is coupled to the cup to resist internal pressure and support the packing, a concave groove is formed on an outer peripheral side surface of the cover, and the cup and the cover are joined by a side caulking in which a cylindrical side surface of the cup is pushed into the concave groove and caulked. A wax thermoelement characterized by the above.

2. The inner peripheral diameter of the cylindrical shape of the cup is substantially the same diameter except for the side caulking portion, and is in a straight line parallel to the axis in a cross section along the axis. The cover is positionally adjusted with respect to the cup according to the internal volume of the wax filling portion of the cup and is joined by the side caulking. The wax thermoelement according to claim 1, characterized by the above.

3. The inner peripheral diameter of the cylindrical shape of the cup is substantially the same diameter corresponding to the outer peripheral diameter of the disc shape of the cover except for the packing portion. The cover is positionally adjusted with respect to the cup according to the internal volume of the wax filling portion of the cup and is joined by the side caulking. The wax thermoelement according to claim 1, characterized by the above.

4. A method for manufacturing a wax thermoelement, the wax thermoelement comprising a housing filled with wax, a piston rod that can project and retract with respect to the housing, and a packing made of a ring-shaped rubber material fitted to the piston rod to seal the wax, wherein the housing is composed of a bottomed cylindrical cup filled with the wax, and a disc-shaped cover that is coupled to the cup to resist internal pressure and support the packing, a concave groove is formed on an outer peripheral side surface of the disc-shaped cover, after inserting the cover into the cup, the cylindrical side surface of the cup is pushed into the concave groove and plastically deformed, and the cover is caulked and joined to the cup by side caulking. A method for manufacturing a wax thermoelement characterized by the above.

5. The process of pushing the side surface of the cup into the concave groove for plastic deformation is carried out by caulking, which presses a metal blade against the cup for plastic deformation, or by bulging, which presses the cup with the pressure of an elastic body or a fluid for plastic deformation. The method for manufacturing a wax thermoelement according to claim 4, characterized in that it is carried out in this way.

6. The process of pushing the side surface of the cup into the concave groove for plastic deformation is carried out by caulking after adjusting the position of the cover so that the lift amount at a predetermined temperature of the piston rod becomes a constant value in accordance with the internal volume of the wax filling portion of the cup, taking into account the inner diameter of the cup and the volume of the packing. The method for manufacturing a wax thermoelement according to claim 4 or 5, characterized in that it is carried out in this way.

Images