Thermo-actuator

Abstract

To provide a thermo-actuator capable of keeping an open state of a driven member even when an ambient temperature drops after operation malfunction release of the driven member such as a louver.SOLUTION: A thermo-actuator comprises: a thermoelement 2 having a piston rod 3 that protrudes as an ambient temperature rises; a first rod 5 that is freely extractable and retractable relative to a case (first case 4), and moves in and out in conjunction with the piston rod 3; a main spring (first spring 6) that urges the first rod in a retraction direction; and an auxiliary spring (second spring 9) that is locked in a compressed state by a locking mechanism (retaining ring 10). The locking mechanism is configured so that when a predetermined or larger axial force acts on the first rod due to a reaction force exerted by the thermoelement to push out the piston rod caused by a malfunction of a driven member (louver) that is driven in conjunction with the first rod, locking is released, and the protruding first rod, urged by the auxiliary spring (second spring), does not retract.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a thermoactuator, and more particularly to a thermoactuator equipped with an auxiliary spring that maintains the protruding length of the rod even when the temperature around the thermoelement drops in order to avoid overheating when abnormal axial force is generated. [Background technology]

[0002] Conventionally, it is known that an actuator that operates according to engine coolant temperature or oil temperature opens and closes (drives) a driven member such as a louver (shielding plate) that is driven in conjunction with the protruding and retracting movement of a rod to adjust the amount of outside air sent to a heat exchanger or engine. However, due to environmental changes or driving on rough roads, foreign matter may get caught in the driven member such as a louver, causing the driven member to stick or become difficult to move, resulting in a malfunction. If the driven member such as a louver is closed at that time, the air supply to the engine is cut off, the oil temperature rises, and in the worst case, a problem occurs in which this can lead to overheating. For this reason, it is necessary to open the driven member by some means and maintain the open state even when the surrounding temperature drops.

[0003] Although conventional thermoactuator structures can generate a force to release malfunctions such as sticking caused by foreign objects by pushing out the piston rod of the thermoelement, there is a problem that it is difficult to make the user aware of the occurrence of an abnormality because the thermoactuator operates normally after that. In addition, once a thermoactuator has been released from sticking, it may become deformed internally due to abnormal stress, and the specified lift (rod protrusion length) may not be obtained. If a thermoactuator subjected to abnormal stress continues to operate normally, the specified lift may not be obtained, which may lead to the problem of the engine overheating.

[0004] For example, Patent Document 1 discloses a thermoactuator having a locking function in which a guide body 11 supporting a retainer 15 is provided with a cylindrical portion 11a rising from a base end, a tapered portion 11c whose outer diameter increases towards the tip of the cylindrical portion, and an engagement groove 11d for a locking member that is recessed in the axial direction subsequent to the tapered portion, and which can smoothly lock the retainer 15 when the retainer 15 is in a lifted state (see claim 1 in the claims of Patent Document 1, paragraphs

[0025] to

[0036] of the specification, Figures 1 to 5 of the drawings, etc.).

[0005] However, the thermoactuator with a locking function described in Patent Document 1 is structured to open and lock when a certain high lift is reached when an abnormally high temperature occurs, and is not designed to deal with the occurrence of abnormal loads such as the bite of a foreign object, etc. For this reason, if a certain lift is not reached when an expected abnormal load occurs, the thermoactuator may not be able to open and may return to normal operation. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2017-223332 A Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, the present invention has been devised to solve the above problems, and its object is to provide a thermoactuator equipped with an auxiliary spring that applies force to maintain the protruding length of the rod, which can maintain the open state of a driven member such as a louver even when the ambient temperature drops after a malfunction of the driven member is removed. [Means for solving the problem]

[0008] The thermoactuator according to the first invention is a thermoactuator that is a temperature-sensitive control device, comprising a thermoelement having a piston rod that protrudes as the surrounding temperature rises, a case attached to the thermoelement, a first rod that is attached to the case so as to be able to protrude and retract freely and that protrudes and retracts in conjunction with the piston rod, a main spring that urges the first rod in the retracting direction, and further comprises an auxiliary spring that is locked in a compressed state by a locking mechanism, wherein the locking mechanism is configured to be released when a predetermined or greater axial force acts on the first rod due to a reaction force from the thermoelement pushing out the piston rod due to a malfunction of a driven member that is driven in conjunction with the first rod, and the first rod that has been urged by the released auxiliary spring is retracted and does not retract.

[0009] The thermoactuator according to a second aspect of the present invention is characterized in that, in the first aspect, the locking mechanism is a mechanism in which the lock is released when a load equal to or greater than a predetermined value is applied to the locking member, causing it to deform or break.

[0010] The thermoactuator according to a third invention is characterized in that, in the second invention, the locking member is hooked onto a tapered section whose diameter gradually increases, a slit is formed in the locking member, and when a predetermined or greater axial force is applied to the first rod, the locking member moves along the tapered section, widening the slit, and the locking member falls off, thereby releasing the lock.

[0011] The thermoactuator according to the fourth invention is characterized in that, in the second invention, the locking member is hooked onto a locking portion, and when an axial force greater than a predetermined value is applied to the first rod, the locking member comes off the locking portion and falls off, thereby releasing the lock.

[0012] The thermoactuator according to the fifth invention is characterized in that, in the first invention, the locking mechanism locks the auxiliary spring by directly hooking it onto a locking portion, and when a predetermined or greater axial force is applied to the first rod, the auxiliary spring disengages from the locking portion, thereby releasing the lock.

[0013] The thermoactuator according to a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, further comprises a second rod interposed between the piston rod and the first rod and adapted to move forward and backward in conjunction with the piston rod, and when no axial force of a predetermined level or more is acting on the first rod, there is a gap between the first rod and the second rod, and the motion of the second rod is transmitted to the first rod via the auxiliary spring, and when an axial force of a predetermined level or more is acting on the first rod, the locking mechanism is released, the gap disappears, and the first rod and the second rod come into contact with each other, thereby transmitting the motion of the second rod to the first rod.

[0014] The thermoactuator of the seventh invention is characterized in that, in the sixth invention, when an axial force of a predetermined value or more is applied to the first rod, the locking mechanism is released and the protruding length of the first rod is maintained by the biasing force of the auxiliary spring, and then the protruding motion of the piston rod caused by an increase in ambient temperature is transmitted to the first rod via the second rod, causing the first rod to protrude further. Effect of the Invention

[0015] According to the first to seventh inventions, the locking mechanism is provided with an auxiliary spring, and is released when a predetermined axial force or more acts on the first rod due to a reaction force of the thermoelement pushing out the piston rod caused by a malfunction of the driven member driven in conjunction with the first rod, and the first rod, which is pushed out by the piston rod under the force of the released auxiliary spring and once protruded, does not recede and does not retract even if the temperature around the thermoelement drops, so that the driven member can be kept open even if the temperature around the thermoelement drops after the malfunction of the driven member is released, and overheating, which is the worst case scenario, can be prevented. Also, according to the first to seventh inventions, the driven member such as a louver is always open after a malfunction occurs in the driven member, i.e., the driven member is open even at low temperatures, so that the user can be made aware of an abnormality.

[0016] In particular, according to the second and third inventions, the locking is released when the locking member deforms or breaks, so that the locking mechanism can be achieved with a simple and inexpensive configuration, and the driven member can be reliably held in the open state by being biased by the auxiliary spring.

[0017] In particular, according to the fourth invention, the lock is released when the locking member disengages from the locking portion and falls off, which makes it possible to simplify and reduce the cost of the locking mechanism and reliably maintain the driven member in the open state by being biased by the auxiliary spring.

[0018] In particular, according to the fifth invention, the locking mechanism is locked by directly hooking the auxiliary spring onto the locking portion, and when a predetermined axial force or more is applied to the first rod, the auxiliary spring disengages from the locking portion, thereby releasing the lock. This eliminates the need for a locking member, allows the locking mechanism to have a simple and inexpensive configuration, and eliminates the risk of the locking member getting caught along the way, so that the auxiliary spring can reliably bias the driven member to hold it in the open state.

[0019] In particular, according to the sixth invention, when an axial force equal to or greater than a predetermined value is not acting on the first rod, the movement of the second rod is transmitted to the first rod via the auxiliary spring, and when an axial force equal to or greater than a predetermined value acts on the first rod, the first rod and the second rod abut, thereby transmitting the movement of the second rod to the first rod.Therefore, it is possible to effectively achieve both sensing an axial force equal to or greater than a predetermined value on the first rod and maintaining the driven member in an open state, and reliably transmitting the movement of the piston rod, which protrudes as the ambient temperature rises, to the first rod.

[0020] In particular, according to the seventh invention, when the temperature becomes high, the thermoelement (pellet) is activated and the driven member can be opened. Even in a state in which some adhesion force remains even after the adhesion is released and a certain protrusion length cannot be obtained with the load of the auxiliary spring, the thermoelement (pellet) is activated to open the driven member, thereby preventing engine overheating. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a cross-sectional view showing the configuration of a thermoactuator according to an embodiment of the present invention. [Diagram 2] Fig. 2(a) is an enlarged view of part A in Fig. 1 under normal conditions, Fig. 2(b) is an enlarged view of part A in Fig. 1 under abnormal load conditions, Fig. 2(c) is a plan view showing the retaining ring under normal conditions, and Fig. 2(d) is a plan view showing the retaining ring under abnormal axial force conditions. [Diagram 3] Fig. 3(a) is a view corresponding to the enlarged view of part A in Fig. 1 showing a retaining ring according to another embodiment in normal operation, Fig. 3(b) is a view corresponding to the enlarged view of part A in Fig. 1 showing a retaining ring according to another embodiment in abnormal axial force generation, Fig. 3(c) is a plan view showing a retaining ring according to another embodiment in normal operation, and Fig. 3(d) is a plan view showing a retaining ring according to another embodiment in abnormal axial force generation. [Figure 4] FIG. 4(a) is a view corresponding to an enlarged view of part A in FIG. 1, showing a locking mechanism according to another embodiment, and FIG. 4(b) is a view corresponding to an enlarged view of part A in FIG. 1, showing a locking mechanism according to another embodiment when abnormal axial force is generated. [Diagram 5] FIG. 5 is a diagram showing normal operation of the thermoactuator of the above, where (a) shows the state before the temperature rises, and (b) shows the state after the temperature rises. [Figure 6] FIG. 6 is a diagram showing the operation of the thermoactuator after a malfunction occurs, where (a) shows the operation when the malfunction occurs, (b) shows the operation when the malfunction is resolved, and (c) shows the operation when the louver is open. [Figure 7] Figure 7 is a diagram showing the operation of the thermoactuator when it is fully open, where (a) shows the open lock state in which the first rod is held in a specified lift state by the auxiliary spring similar to that in Figure 6(c) and the louver is held in the open state, and (b) shows the fully open state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A thermoactuator according to an embodiment of the present invention will now be described in detail with reference to the drawings.

[0023] <Thermoactuator configuration> The configuration of a thermoactuator 1 according to an embodiment of the present invention will be described with reference to Figures 1 to 3. Figure 1 is a cross-sectional view showing the configuration of a thermoactuator 1 according to an embodiment of the present invention.

[0024] 1, a thermoactuator 1 according to an embodiment of the present invention is a temperature-sensing control device that includes a thermoelement 2 and functions both as a temperature sensor and as an actuator that performs a control operation (driving operation). The thermoactuator 1 according to this embodiment will be described by taking as an example a thermoactuator that senses the oil temperature of an engine to open and close a louver (shielding plate), which is a driven member, to adjust the amount of air blown.

[0025] (Thermoelement) This thermoelement 2 comprises a housing 20, which is a container made of metal such as brass in which wax such as paraffin wax is enclosed, and a stainless steel piston rod 3 which can be freely protruded and retracted into the housing 20, and the piston rod 3 protrudes due to the expansion of the wax in the housing 20 as the temperature around the thermoelement 2 rises. Of course, the wax enclosed in the housing 20 is not limited to paraffin wax, and any material having predetermined thermal expansion characteristics with a relatively large volume change, such as micro wax, can be applied to the present invention.

[0026] Moreover, the thermoactuator 1 in this embodiment includes a first case 4 in which the thermoelement 2 is mounted, a first rod 5 mounted so as to be able to freely protrude and retract relative to the first case 4, and a first spring 6 which is a main spring that biases the first rod 5 in the retracting direction.

[0027] A second case 8 is connected to the first rod 5, and a second spring 9, which is an auxiliary spring that biases the second case 8 and the first rod 5 in the protruding direction, is interposed in the second case 8. The second spring 9 is hooked and locked to the second rod 11 by a retaining ring 10, which is a locking member, in a compressed state.

[0028] This second rod 11 is inserted between the piston rod 3 and the second case 8, and when the piston rod 3 protrudes due to the expansion of the wax, it is pushed out by this piston rod 3, pushing out the second case 8 and the first rod 5 connected to this second case 8 in a domino effect. However, as shown in Fig. 1, under normal circumstances, the piston rod 3 and the second rod 11 are in contact with each other, and the second case 8, which is integrated with the first rod 5, and the second rod 11 are separated from each other.

[0029] An O-ring 12 made of acrylic rubber (ACM) is interposed between the thermo-element 2 and the first case 4 to seal the portion where it fits with the engine. The first case 4, together with the thermo-element 2, is attached by crimping to a support plate 13, which is a support member, and the entire thermoactuator 1 is fixed and supported.

[0030] (Case 1) The first case 4 is made of stainless steel (SUS430) and is a cylindrical case having an open end 4a at one end and a tapered portion 4b at the other end where the diameter is tapered. The open end 4a of this first case 4 is attached to the thermo-element 2 and the support plate 13. A bearing 41 made of polyphenylene sulfide (PPS resin) is attached to the tapered portion 4b of the first case 4, and a first rod 5 described below is configured to be able to protrude and retract through this bearing 41. An O-ring 42 made of EPDM (ethylene propylene diene monomer), a synthetic rubber, is attached and sealed to the outside of the bearing 41 of the tapered portion 4b (the protruding direction side of the first rod 5) to prevent external liquid and dust from entering the thermoactuator 1.

[0031] (First rod) The first rod 5 is made of a bar material of stainless steel (SUS430), and a push rod 51 connected to the louver is fitted to the tip of the first rod 5.

[0032] (Main spring) The first spring 6, which is the main spring, is a coil spring made of stainless steel wire (SUS304), with one end abutting against the inner wall of the first case 4 on the reduced diameter portion 4b side and the other end hooked onto the second case 8 connected to the first rod 5. As a result, as described above, the first spring 6 biases the first rod 5 in the sinking direction, that is, in the direction of drawing the first rod 5 into the first case 4 when the temperature drops. The biasing force of the first spring 6, which is the main spring, is set to 48 to 55 N.

[0033] (Case 2) The second case 8 is made of the same stainless steel material (SUS430) as the first rod 5, and is an integral member connected to the first rod 5. The second case 8 is a cylindrical member with one end closed, and has a recess 81 formed in the center for inserting the second rod 11, with the outside of the recess 81 providing a space for inserting the second spring 9. In addition, a brim-shaped latch portion 82 folded back outward is formed at the open end of the second case 8, and the above-mentioned first spring 6 is latched on to it.

[0034] (auxiliary spring) The second spring 9, which is an auxiliary spring, is a coil spring made of stainless steel wire (SUS304) like the first spring 6, and in a compressed state, one end of the spring abuts against the inner wall of the closed end of the second case 8, and the other end of the spring abuts against a retaining ring 10 hooked onto the second rod 11. The retaining ring 10 will be described later. The biasing force of the second spring 9, which is an auxiliary spring, is set to 55 to 93 N, which is greater than the biasing force of the first spring 6, in order to counter the biasing force of the first spring 6 and hold the louvers in the open state.

[0035] (Second rod) The second rod 11 has an end 111 on the side that is inserted into the recess 81, which expands in diameter in a mushroom shape, and is hooked by a stainless steel wire ring 14 to prevent the second rod 11 from coming off the recess 81. In addition, a tapered portion 112 is formed on the other end of the second rod 11 on the piston rod 3 side, the diameter of which gradually expands as it approaches the piston rod 3 side, and a retaining ring 10 is hooked on this tapered portion 112.

[0036] <Latching mechanism> Next, the retaining ring 10, which is a locking mechanism (locking member) according to an embodiment of the present invention, will be described with reference to Fig. 2. Fig. 2(a) is an enlarged view of part A in Fig. 1 under normal conditions, and Fig. 2(b) is an enlarged view of part A in Fig. 1 under abnormal load conditions. Fig. 2(c) is a plan view showing the retaining ring 10 under normal conditions, and Fig. 2(d) is a plan view showing the retaining ring 10 under abnormal load conditions.

[0037] As shown in Fig. 2, the retaining ring 10, which is a retaining mechanism (retaining member) according to the embodiment of the present invention, is C-shaped with a slit 10a formed therein. On the other hand, when a malfunction occurs such that the louver, which opens and closes in conjunction with the protruding and retracting movement of the first rod 5 via the push rod 51, becomes stuck or difficult to move due to the ingestion of foreign matter or the like, the thermo-element 2 pushes out the piston rod 3, and a reaction force of a predetermined or greater axial force (100 N or greater as described below) acts on the first rod 5 via the push rod 51 connected to the louver. Then, as described above, since the second case 8 and the second rod 11 are separated from each other, the abnormal axial force acting on the first rod 5 acts on the retaining ring 10 via the second spring 9 compressed so that the steel wires come into contact with each other.

[0038] When an abnormal axial force acts on the retaining ring 10, the retaining ring 10 is hooked to the tapered portion 112 of the second rod 11, so that the retaining ring 10 moves in the direction of the arrow in FIG. 2(b) of the tapered portion 112. Then, the slit 10a deforms and widens, and the retaining ring 10 falls off the tapered portion 112 of the second rod 11, and the locking mechanism is released. The load at which the slit 10a of the retaining ring 10 starts to widen is set to 100 N, as described later. Of course, it goes without saying that the locking member according to the present invention may be designed to be released by breaking rather than by deformation.

[0039] Next, a retaining ring 10' which is a retaining mechanism (retaining member) according to another embodiment of the present invention will be described with reference to Fig. 3. Fig. 3(a) is a view corresponding to the enlarged view of part A in Fig. 1 showing the retaining ring 10' according to another embodiment under normal conditions, and Fig. 3(b) is a view corresponding to the enlarged view of part A in Fig. 1 showing the retaining ring 10' when abnormal axial force is generated. Fig. 3(c) is a plan view showing the retaining ring 10' under normal conditions, and Fig. 3(d) is a plan view showing the retaining ring 10' when abnormal axial force is generated.

[0040] A retaining ring 10' according to another embodiment differs from the previously described retaining ring 10 in that the thickness of the retaining ring 10' is thinner than the thickness of the previously described retaining ring 10, and that the retaining ring 10', which is a locking member, is not hooked to the tapered portion 112 but is hooked to the first locking portion 113 (locking portion) of the second rod 11. Therefore, these points will be described, and the same components as those described above will be denoted by the same reference numerals and descriptions thereof will be omitted.

[0041] The thickness of the retaining ring 10' is thinner than the thickness of the retaining ring 10, and the retaining ring 10' is hooked to a first locking portion 113 formed on the lower end of the second rod 11 on the thermo-element 2 side. Therefore, when an abnormal axial force acts on the retaining ring 10', the retaining ring 10' does not shift along the tapered portion 112 and move, but the ring-shaped retaining ring 10' falls outward while hooked on the first locking portion 113 and deforms into a truncated cone shape, as shown by the arrow in Fig. 3(b), and as a result, the retaining ring 10' falls off the first locking portion 113 of the second rod 11, and the locking mechanism is released.

[0042] As described above, the locking mechanism has been described as an example in which the lock is released by deformation or breakage of the locking member, namely, the retaining ring 10 or the retaining ring 10', when an axial force equal to or greater than a predetermined value is applied to the first rod 5. However, the locking mechanism of the present invention is not limited to a mechanism in which the lock is released by deformation or breakage of the locking member, so long as the lock is released when an axial force equal to or greater than a predetermined value is applied to the first rod 5.

[0043] Next, a locking mechanism according to another embodiment in which the lock is not released by deformation or breakage of the locking member will be described with reference to FIG. 4. FIG. 4(a) is a view corresponding to the enlarged view of part A in FIG. 1 showing the locking mechanism according to another embodiment, and FIG. 4(b) is a view corresponding to the enlarged view of part A in FIG. 1 showing the locking mechanism according to another embodiment when an abnormal axial force is generated. The locking mechanism according to this embodiment differs from the above-mentioned locking mechanism (the retaining ring 10 and the retaining ring 10' which are the locking members) in that there is no locking member itself, and the second spring 9' according to the modified auxiliary spring is directly hooked to the second locking portion 114 of the second rod 12. Therefore, this point will be described, and the same components are given the same symbols and the description will be omitted.

[0044] The locking mechanism of this embodiment shown in Figure 4 is a modified second spring 9' in which the diameter of the spring steel wire at the lower end of the second spring 9 on the thermo-element 2 side is reduced, and a second locking portion 114 is formed at the lower end of the second rod 12 on the thermo-element 2 side, and the spring steel wire of the second spring 9' is directly hooked to this second locking portion 114.

[0045] For this reason, when abnormal axial force acting on first rod 5 is transmitted to second spring 9', the lower end of second spring 9', whose spring steel wire has a reduced diameter, is pressed and spreads past second locking portion 114, as shown by the arrow direction in Fig. 4(b), and falls off second locking portion 114 of second rod 11, releasing the lock of the locking mechanism. This eliminates the need for a locking member, allowing the locking mechanism to have a simple and inexpensive configuration, and there is no risk of the locking member getting caught midway, so the louvers can be reliably biased by second spring 9', which is an auxiliary spring, to hold them in the open state.

[0046] <Thermoactuator operation> Next, the operation of the thermoactuator 1 will be described with reference to Figures 5 and 6. Figure 5 is a diagram showing normal operation of the thermoactuator 1, where (a) shows the state before the temperature rises and (b) shows the state after the temperature rises. Also, Figure 6 is a diagram showing operation of the thermoactuator 1 after a malfunction occurs, where (a) shows the operation when the malfunction occurs, (b) shows the operation when the malfunction is removed, and (c) shows the operation when the louver is open.

[0047] 5(a) and 5(b), in normal operation of the thermoactuator 1, the piston rod 3 protrudes due to the expansion of wax in the housing 20 as the temperature around the thermoelement 2 rises. Then, the piston rod 3 pushes out the second rod 11.

[0048] At this time, as described above, the second case 8 and the second rod 11, which are integrated with the first rod 5, are separated by the separation distance D1. However, as described above, the second spring 9 is housed in the second case 8 in a compressed state. Therefore, the protruding force (lift force) of the piston rod 3 is transmitted to the second rod 11, and then transmitted to the second spring 9 via the retaining ring 10 hooked to the tapered portion 112, and then transmitted from the closed end of the second case 8 to the first rod 5 integrated therewith, lifting it up by the lift distance L1 (the increase in the protruding length of the first rod 5), and operating in the direction of opening the louver. In the illustrated embodiment, it is assumed that the lift distance L1 = 8.0 mm and the separation distance D1 = 1.0 mm.

[0049] When the temperature drops, the wax in the housing 20 shrinks as the temperature around the thermo-element 2 drops, and the piston rod 3 retracts into the housing 20. Then, the first rod 5 and second case 8 are lifted down toward the piston rod 3 by the biasing force of the first spring 6, which is the main spring, and the second rod 11 is also lifted down in a domino effect via the second spring 9.

[0050] In this way, during normal operation when no malfunction occurs, the thermoelement 2 detects the change in oil temperature and repeats the operations shown in Figures 5(a) and 5(b) to open and close the louver connected to the push rod 51. As mentioned above, the biasing force of the first spring 6, which is the main spring, is set at 48-55N < the biasing force of the second spring 9, which is the auxiliary spring, is set at 55-93N, so the second spring does not bend.

[0051] On the other hand, if the louver becomes stuck due to a foreign object being caught in it, causing a malfunction, the push rod 51 and the first rod 5 connected to the louver are also locked. In this state, when the temperature rises, the wax of the thermoelement 2 expands, causing the piston rod 3 to protrude. However, if the louver is stuck, the first rod 5 also protrudes and cannot be lifted up, and an abnormal axial force is transmitted to the first rod 5 and the thermoelement 2 in reaction to the lift force (ejection force) of the piston rod 3 generated by the piston rod 3. If the abnormal axial force transmitted to the thermoelement 2 becomes higher than the biasing force of the second spring 9 (= 55 to 93 N) and exceeds 100 N, the housing 20 may be deformed, making it impossible to continue using the device.

[0052] Therefore, as described above, when an abnormal axial force exceeding 100N acts on the retaining ring 10, the slit 10a is set to deform and begin to widen. In other words, as shown in FIG. 6(a), when a malfunction such as the sticking of the louver occurs, the separation distance between the second case 8 and the second rod 11 is shortened, the second spring 9 is shortened, and the steel wires of the second spring 9 come into contact with each other, so that the slit 10a of the retaining ring 10 begins to deform and widen (see also FIG. 2). As shown in FIG. 6(b), the retaining ring 10 falls off the tapered portion 112 of the second rod 11, and the locking mechanism is released. As shown in FIG. 6(c), the second spring 9 biases the first rod 5, preventing it from retreating and sinking, and maintaining the open state of the louver even when the temperature around the thermo-element 2 drops. Of course, the first rod 5 may be biased indirectly by the biasing force of the second spring 9, and the second spring 9 does not have to directly press the first rod 5. In addition, the release of the locking mechanism of the present invention can be achieved by appropriately selecting the spring constant of the second spring 9 and the strength of the retaining ring 10 so that the retaining ring 10 falls off when an abnormal axial force acts on it, regardless of whether the steel wires of the second spring 9 are in contact with each other or not.

[0053] In this way, with the thermoactuator 1 of this embodiment, when an axial force greater than a predetermined value is applied to the first rod 5, the retaining ring 10, which is a locking member, is released from its locking state, and even after a foreign object or the like has become caught and the temperature around the thermoelement 2 has dropped, the force of the second spring 9 can be used to maintain the louvers in a minimum open state by maintaining a predetermined protruding length of the first rod 5, thereby preventing overheating.

[0054] As described above, the locking member may be a retaining ring 10', and when an abnormal axial force acts on the retaining ring 10', as shown by the arrow direction in Figure 3(b), the ring-shaped retaining ring 10' falls outward while still hooked on the first locking portion 113, and deforms into a truncated cone shape, thereby expanding, and the retaining ring 10' falls off the first locking portion 113 of the second rod 11, thereby releasing the lock of the locking mechanism.

[0055] Furthermore, as described above, when the abnormal axial force acting on the first rod 5 is transmitted to the second spring 9', the lower end of the second spring 9', whose diameter of the spring steel wire has been reduced, is pressed and expands, climbing over the second locking portion 114, as shown by the arrow direction in Figure 4(b), and falls off from the second locking portion 114 of the second rod 11, thereby releasing the lock of the locking mechanism.

[0056] On the other hand, according to the thermoactuator 1, in normal operation as shown in Fig. 5, the motion of the second rod 11 is transmitted to the first rod 5 via the second spring 9, and when a malfunction of the louver occurs, the first rod 5 and the second rod 11 come into contact with each other, thereby transmitting the motion of the second rod 11 to the first rod 5. This makes it possible to effectively balance between sensing an axial force of a predetermined level or more on the first rod 5 to hold the louver in the open state, and reliably transmitting the motion of the piston rod 3, which protrudes in response to an increase in the surrounding temperature, to the first rod 5.

[0057] In addition, as shown in FIG. 6(c), the louvers are kept constantly open after the occurrence of abnormal axial force, i.e., the louvers remain open even at low temperatures, making the user aware of the abnormality and providing an incentive to take the vehicle to a repair shop or the like while the engine is running.

[0058] Figure 7 is a diagram showing the operation of the thermoactuator 1 when it is fully open, where (a) shows the open lock state in which the second spring 9, the same as in Figure 6(c), holds the first rod 5 in a specified lifted state and holds the louver in an open state, and (b) shows the fully open state.

[0059] As shown in Fig. 7(a), the second spring 9 holds the first rod 5 in a lift state with a predetermined protruding length, and the louvers are held in an open-locked state in which they are open, and when the oil temperature rises, as shown in Fig. 7(b), the protruding motion of the piston rod 3 is transmitted to the first rod 5 via the second rod 11, causing the first rod 5 to protrude further from the open-locked state of Fig. 7(a) and the louvers to enter a fully open state. This is because, even in a state in which some sticking force remains after the thermoelement 2 has been released from a malfunction such as sticking, and a certain lift cannot be obtained with the biasing force of the second spring 9, the thermoelement 2 (pellet) operates to open the louvers, preventing engine overheating.

[0060] The thermoactuator 1 according to the embodiment of the present invention has been described in detail above, but the above-mentioned and illustrated embodiments are merely examples of the present invention. Therefore, the technical scope of the present invention should not be interpreted as being limited by these. In particular, the materials of each member are merely examples, and it goes without saying that they can be appropriately changed to other materials having equivalent strength. [Explanation of symbols]

[0061] 1: Thermoactuator 2: Thermoelement 20: Housing 3: Piston rod 4: Case 1 4a: Open end 4b: Reduced diameter part 41: Bearing 42: O-ring 5: First rod 51: Push rod 6: 1st spring (main spring) 8: Second case (first rod) 81: Recess 82: Hook stopper 9,9': Second spring (auxiliary spring) 10, 10': retaining ring (retaining member, retaining mechanism) 10a, 10a': Break 11: 2nd Rod 111: End 112: Tapered section 113: First locking portion (locking portion) 114: Second locking portion (locking portion) 12: O-ring 13: Support plate 14: Wiring

Claims

1. A thermoactuator that is a temperature-sensitive control device, The thermoelement has a piston rod that projects in response to an increase in the surrounding temperature, a case attached to the thermoelement, a first rod that is attached to the case so as to be able to project and retract freely and that projects and retracts in conjunction with the piston rod, and a main spring that urges the first rod in the retracting direction, and an auxiliary spring that is locked in a compressed state by a locking mechanism, The locking mechanism is configured such that when a predetermined axial force or more is applied to the first rod due to a reaction force of the thermoelement pushing out the piston rod caused by a malfunction of a driven member driven in conjunction with the first rod, the locking mechanism is released, and the first rod, which has been urged by the released auxiliary spring and protrudes, is retracted and does not retract. A thermo actuator characterized by:

2. The locking mechanism is a mechanism in which the locking member is deformed or broken when a load equal to or greater than a predetermined value is applied, thereby releasing the locking. The thermoactuator according to claim 1 .

3. The locking member is hooked to a tapered portion whose diameter gradually increases, and a slit is formed in the locking member. When a predetermined axial force or more is applied to the first rod, the locking member moves along the tapered portion, widening the slit, and the locking member falls off, thereby releasing the lock. The thermoactuator according to claim 2 .

4. The locking member is hooked to a locking portion, and when a predetermined axial force or more is applied to the first rod, the locking member comes off the locking portion and falls off, thereby releasing the lock. The thermoactuator according to claim 2 .

5. The locking mechanism is engaged by directly hooking the auxiliary spring to a locking portion, and when a predetermined axial force or more is applied to the first rod, the auxiliary spring is disengaged from the locking portion, thereby releasing the lock. The thermoactuator according to claim 1 .

6. A second rod is interposed between the piston rod and the first rod and moves in a protruding and retracting manner in conjunction with the piston rod. When no axial force of a predetermined magnitude or more is applied to the first rod, a gap is formed between the first rod and the second rod, and the motion of the second rod is transmitted to the first rod via the auxiliary spring, When a predetermined axial force or more is applied to the first rod, the locking mechanism is released, the gap disappears, and the first rod and the second rod come into contact with each other, so that the motion of the second rod is transmitted to the first rod.

6. The thermoactuator according to claim 1, wherein

7. When a predetermined axial force or more is applied to the first rod, the locking mechanism is released and the protruding length of the first rod is maintained by the biasing force of the auxiliary spring, and then, the protruding motion of the piston rod caused by an increase in the surrounding temperature is transmitted to the first rod via the second rod, causing the first rod to protrude further. The thermoactuator according to claim 6 .

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