JP4801389B2 - Drive device - Google Patents

Description

  The present invention relates to a drive device that utilizes a pressure change of a working fluid, particularly a large pressure change accompanying a phase transition.

  2. Description of the Related Art Conventionally, as a driving device that utilizes pressure changes accompanying a phase transition of a working fluid, for example, an inner space (working space) of an elastic single-layer bellows is filled with a working fluid, and a heater is disposed in the working space. There was a thing (patent document 1).

  In this apparatus, the temperature of the working fluid that is liquid at room temperature is raised to the boiling point or more by vaporizing it by energizing the heater (energizing on) to generate heat. As a result, the pressure in the working space increases, the volume increases, and the bellows expands. Bellows generally have a very large radial spring constant compared to an axial spring constant. Therefore, when the volume of the working space increases, the bellows mainly extends in the axial direction.

  On the other hand, in the bellows in a state where the working fluid is vaporized, when energization to the heater is stopped (energization off), the bellows and the working fluid are naturally cooled, and when the temperature falls below the boiling point, the working fluid is liquefied. As a result, the pressure in the internal space decreases, the volume decreases, and the bellows contracts.

As described above, the bellows can be extended and contracted by turning on / off the power to the heater.
JP 2003-35303 A JP 2000-219134 A JP 2001-163278 A JP 2001-315636 A Japanese Patent Laid-Open No. 2002-267921 JP 2002-336265 A

In the above-described driving device, the bellows may have a larger outer shape for other purposes to obtain a large driving force. In such a case, the working space becomes large and the amount of working fluid accommodated therein increases. For this reason, in order to drive and run the bellows, the amount of heat required to vaporize the working fluid becomes extremely large. For example, when the bellows diameter and length are n times, the amount of heat required to vaporize all the working fluid is n ³ times.

  Furthermore, since the time required for vaporization and liquefaction increases as the amount of working fluid increases, the response time from turning on / off the heater to the expansion and contraction of the bellows increases, and the operating speed of the drive device decreases. There was a problem.

  On the other hand, there is a drive device that expands and contracts the bellows by vaporizing only the working fluid around the heater without vaporizing all the working fluid in the bellows. In this device, even if the outer shape of the bellows becomes large, the bellows can be expanded and contracted without increasing the amount of heat required to vaporize the working fluid. However, when the outer shape of the bellows is increased, the ratio of the working fluid sealed in the working space that is vaporized by the heat generated by the heater is significantly reduced, so that the pressure increase amount and the volume increase amount in the working space are relatively small. That is, the extension amount of the bellows becomes relatively small. For this reason, there has been a problem that the driving amount of the driving device is reduced as the outer shape of the bellows is increased.

In order to solve the above-described problem, in the driving device of the present invention, a telescopic hollow outer structure, and an expansion / contraction accommodated in the outer structure and forming an operating space between the outer structure and the outer structure. A possible hollow inner structure, a working fluid enclosed in a working space between the outer structure and the inner structure, an inner surface of the outer structure and an outer surface of the inner structure in the working space A heating element provided in a layered manner on at least one of the above, a shape holding ring fitted into the outer surface of the outer structure and the inner surface of the inner structure outside the working space, and the layered heating element By heating the working fluid by generating heat, the working fluid is transferred from a liquid phase to a gas phase to increase the pressure in the working space, thereby extending the outer structure and the inner structure. It is said.

The layered heating element is preferably provided on each of the inner surface of the outer structure and the outer surface of the inner structure in the working space.

The diameter of the shape retaining ring fitted on the outer surface of the outer structure is set so that the working fluid contacts the outer surface of the outer structure when the working fluid is in a liquid phase lower than its boiling point. It is preferable to set the diameter of the shape-retaining ring fitted to the inner surface of the inner structure so that the working fluid is in a liquid phase lower than its boiling point.

The outer structure and the inner structure may have a bellows shape in which a plurality of peaks and valleys are formed at a constant interval.

In this case, the shape retaining ring can be fitted into the outside of the valley portion of the outer structure and the inside of the mountain portion of the inner structure. Moreover, the said outer structure and the said inner structure can make the pitch of the said peak part and a trough part the same.

  The outer structure and the inner structure are preferably made of an elastic material. Examples of the elastic material include elastic rubber such as silicon rubber, metal such as phosphor bronze and nickel, and engineering plastic such as Teflon (registered trademark).

  The heating element can be formed by sticking, coating, vapor deposition, or dipping on at least one of the inner and outer surfaces of the outer structure and the inner and outer surfaces of the inner structure.

  According to the present invention, even when the outer shape of the structure is increased, it is not necessary to increase the amount of heat required for vaporizing the working fluid, and the response time from turning on / off the heater to the expansion and contraction of the structure is increased. Thus, it is possible to provide a driving device that can prevent the reduction of the driving amount or the traveling amount.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the drive device according to the present embodiment includes an outer structure 11, an inner structure 12, a working fluid 21, heating elements (heaters) 31 and 32, and a power source 41. In this driving device, the heat generating elements 31 and 32 supplied with power (applied voltage) (energized) from the power source 41 generate heat, so that the liquid phase portion of the working fluid 21 sandwiched between the heat generating elements 31 and 32 is heated. It is then transferred to the gas phase. As a result, the pressure in the working space increases, and the outer structure 11 and the inner structure 12 expand.

The outer structure 11 and the inner structure 12 have a bellows-like cylindrical shape in which a plurality of peak portions 11a and 12a and valley portions 11b and 12b are formed at regular intervals. The outer structure 11 and the inner structure 12 have the same cylindrical axial length, and the pitch between the peaks 11a of the outer structure 11 is the same as the pitch between the peaks 12a of the inner structure 12. Furthermore, the pitch between the valleys 11b of the outer structure 11 is also the same as the pitch between the valleys 12b of the inner structure 12. The inner structure 12 has a maximum outer diameter larger than the minimum inner diameter of the outer structure 11 and smaller than the maximum outer diameter of the outer structure 11. These structural bodies 11 and 12 are made of an elastic material (for example, elastic rubber such as silicone rubber having a hardness of about 50 (Shore A), metal such as phosphor bronze or nickel, engineering plastic such as Teflon (registered trademark)). Become. In the outer structure 11, the ridge 11 a of the outer structure 11 and the ridge 12 a of the inner structure 12, and the valley 11 b of the outer structure 11 and the valley 12 b of the inner structure 12 correspond to each other. By arranging the inner structure 12, a double structure is used. Both ends in the axial direction of the outer structure 11 and the inner structure 12 are closed by metal ring plate-like sealing plates 15 and 16, respectively. Thereby, the working space 18 sealed between the outer structure 11 and the inner structure 12 is formed. A working fluid 21 is filled and sealed in the working space 18.

  In addition, the outer structure 11 and the inner structure 12 can be formed in a cylindrical shape having a spiral groove instead of the bellows shape. When the spiral groove is formed so as to correspond to the outer structure 11 and the inner structure 12, the inner structure 12 can be easily screwed into the outer structure 11. That is, the inner structure 12 can be arranged inside the outer structure 11 without deforming the outer structure 11 or the inner structure 12. For this reason, the outer structure body 11 and the inner structure body 12 can be comprised with materials, such as a metal which shows high elasticity compared with rubber | gum. Further, instead of the sealing plates 15 and 16, the outer structure 11 and the inner structure 12 may be coupled to each other to close the working space 18.

  As shown in FIGS. 1 and 2, layered (film-like, planar) heating elements 31 and 32 are provided on the inner surface of the outer structure 11 and the outer surface of the inner structure 12, respectively. These heating elements 31 and 32 are formed by, for example, coating or dipping a liquid in which a conductive substance is dissolved, vapor deposition of a conductive substance, and attaching a conductive thin film (for example, a resistance metal foil or a conductive carbon-containing rubber). can do. By making the heating elements 31 and 32 layered (planar), the contact area with the working fluid 21 can be increased as compared with a linear heating element, so that heat conduction to the working fluid 21 can be promoted. it can. Further, by forming the heating elements 31 and 32 in layers, the volume of the working space 18 can be made smaller and the required amount of the working fluid 21 can be suppressed compared to the case where a linear heating element is used. Furthermore, by using a layered structure, the possibility of disconnection that can occur in a linear heating element is extremely reduced, and a highly reliable drive device can be realized. Further, when a hard heating element is disposed in the working space 18, the outer structure 11 and the inner structure 12 are brought into contact with and collide with the outer structure 11 and the inner structure 12. However, by forming the heating elements 31 and 32 in layers, the outer structure 11 and the inner structure 12 can be expanded and contracted smoothly and sufficiently.

  The heating elements 31 and 32 are preferably made of a material having a small temperature coefficient of electric resistance and strong corrosion resistance. For example, when constantan is used, the temperature coefficient of electric resistance is extremely small, and therefore the operating environment of the driving device changes. Even if there is, stable operation can be performed. By making the heating elements 31 and 32 layered (planar), the contact area with the working fluid 21 can be increased as compared with a linear heating element, so that heat conduction to the working fluid 21 can be promoted. it can. The heating elements 31 and 32 may be formed in layers on at least one of the inner and outer surfaces of the outer structure 11 and the inner and outer surfaces of the inner structure 12.

  Conductive wires 411 and 412 are connected to the heating elements 31 and 32, and the conductive wires 411 and 412 are connected to an external power supply 41. The power source 41 is connected to the controller 42 and energizes the heating elements 31 and 32 under the control of the controller 42. The conducting wires 411 and 412 may be connected to the metal sealing plates 15 and 16 that are electrically connected to the heating elements 31 and 32 without being connected to the heating elements 31 and 32.

  Independent outer shape retaining rings 35 are fitted on the outer sides of the valleys 11b of the outer structure 11, and independent inner shape retaining rings 36 are fitted on the inner sides of the peak portions 12a of the inner structure 12, respectively. It is. These shape retaining rings 35 and 36 are made of a rigid material and can be made of, for example, stainless steel. The diameters of the shape retaining rings 35 and 36 are such that when the working fluid 21 is in a liquid phase lower than its boiling point, the outer structure 11 is outside the valleys 11b and the inner structure 12 is inside the peaks 12a. It is just about contacting. These rings 35 and 36 are particularly necessary when the outer structure 11 and the inner structure 12 are made of a material having high elasticity such as rubber as shown in this embodiment. That is, when the working fluid 21 in the working space 18 is heated by these rings 35 and 36 to change the phase from a liquid to a gas and the volume is increased, the outer structure 11 and the inner structure 12 are radially moved. It is possible to suppress stretching and facilitate stretching in the axial direction.

  The working fluid 21 is desirably a liquid that is liquid at room temperature in an environment where the driving device is used and has a boiling point slightly higher than room temperature (a material that is about 5 to 20 ° C. higher than room temperature). When the drive device is used in the human body, a boiling point of 50 ° C. or higher is preferable. For example, PF-5060 (trade name) (boiling point 56 ° C.) manufactured by Sumitomo 3M Limited can be used. Thus, the working fluid 21 can be heated and vaporized with a small amount of electric power by using a substance having a boiling point slightly higher than room temperature. In addition, when used in the human body, safety can be improved compared to a substance having a higher boiling point.

  Furthermore, it is preferable that the working fluid 21 has a small specific heat and latent heat of vaporization. By making the specific heat small, a rapid temperature rise is possible, so that a phase transition with a high response speed can be realized. In addition, when the latent heat of vaporization or heat of vaporization is small, the working fluid 21 can be vaporized with a small amount of heat, so that a phase transition with a high response speed can be realized. These effects work similarly when the working fluid 21 is cooled or liquefied.

  Moreover, it is preferable that the working fluid 21 is inert with respect to the material which comprises the outer structure 11, the inner structure 12, and the heat generating bodies 31 and 32, for example, a fluorine-type liquid can be used. The above-mentioned PF-5060 is a preferable material for the working fluid 21 because it is compatible with this point.

The working fluid 21 is supplied to the working space 18 by a working fluid supplier (working fluid supply means) 24 connected to a conducting tube 23 that passes through the sealing plate 16 and communicates from the outside into the working space 18. The conducting pipe 23 is provided with a valve 25. The valve 25 is opened when the working fluid 21 is supplied to connect the working space 18 and the working fluid supplier 24, and is closed when the supply of the working fluid 21 is completed to prevent backflow from the working space 18 to the outside. . Here, if at least a portion of the sealing plate 16 that penetrates the conducting pipe 23 is made of a material having a cap piercing mechanism, even if the conducting pipe 23 is taken in and out, the viscosity of the material itself constituting the cap piercing mechanism is reduced. The airtightness of the working space 18 can be maintained by elasticity. This eliminates the need for a special configuration for maintaining airtightness when supplying the working fluid 21 and facilitates replenishment of the working fluid 21. The working fluid supplier 24 may be electric or manual, and for example, a syringe can be used. Further, the conducting tube 23 may be disposed so as to penetrate the sealing plate 15.

  A temperature sensor 451 and a pressure sensor 461 are disposed in the working space 18, and the temperature and pressure in the working space 18 can be detected at all times. For the temperature sensor 451, for example, a platinum resistance thermometer can be used. Information detected by the temperature sensor is sent to a temperature measuring device 45 connected by a conducting wire 452. The pressure sensor 461 can use, for example, a piezoresistive semiconductor. Information detected by the pressure sensor 461 is sent to a pressure measuring device 46 connected by a conducting wire 462. The temperature measuring device 45 and the pressure measuring device 46 are connected to the controller 42. The controller 42 supplies power to the heating elements 31 and 32 based on the temperature detection result and the pressure detection result in the working space 18 sent from the temperature measuring device 45 and the pressure measuring device 46. The operation of the power supply 41 can be controlled so as to stop the application.

  The drive device according to the present embodiment can be assembled, for example, in the following order. First, the inner structure 12 is press-fitted into the outer structure 11 so that each mountain portion 11a and each mountain portion 12a correspond to each valley portion 11b and each valley portion 12b. Subsequently, the shape retaining ring 35 is disposed outside each valley 11b, and the shape retaining ring 36 is disposed inside each peak 12a. Next, the axial direction both ends of the bellows-like outer structure 11 and the inner structure 12 are sealed with the sealing plate 15 and the seal so that the working space 18 formed between the outer structure 11 and the inner structure 12 is sealed. The plate 16 is bonded and fixed. Finally, the conducting tube 23 is passed through the sealing plate 16, and the working fluid 21 is filled with the working fluid 21 by the working fluid supplier 24.

  In the drive device according to the present embodiment configured as described above, the heating fluids 31 and 32 to which power is supplied from the power source 41 generate heat, whereby the working fluid 21 is heated and the liquid phase portion is changed to the gas phase. As a result, the pressure in the working space 18 rises, and the outer structure 11 and the inner structure 12 expand accordingly. Since the expansion in the radial direction of the bellows-shaped outer structure 11 and the inner structure 12 is restricted by the shape retaining ring 35 and the shape retaining ring 36, respectively, the outer structure 11 and the inner structure 12 expand in the axial direction. . Further, by utilizing this axial extension, the outer structure 11 and the inner structure 12 can be made to travel together in the extension direction. For example, from a simple discussion, it will now be described that an increase in pressure in the working space 18 causes the outer structure 11 and the inner structure 12 to stretch. FIG. 3 is an enlarged view of a part of the cross section of the working space 18 between the outer structure 11 and the inner structure 12. The distance between the outer structure 11 and the inner structure 12 is d, and the bellows pitch of the outer structure 11 and the inner structure 12 (the distance between adjacent mountain parts 11a (mountain parts 12a) Consider a case where the matching valley portions 11b (interval between valley portions 12b) are ha as shown in FIG. 3A and hb as shown in FIG. 3B (ha <hb). At this time, the area of the region A (hatched portion in FIG. 3) is represented as ha × d in FIG. 3A and hb × d in FIG. 3B. Since the volume of the working space 18 is obtained by integrating the area of the region A in FIG. 3 over the entire length and the circumferential direction of the outer structure 11 and the inner structure 12, the volume of the working space 18 is as shown in FIG. The case becomes larger than the case of FIG. Here, ha <hb, which means that FIG. 3B shows that the outer structure 11 and the inner structure 12 are extended compared to FIG. 3A. That is, when the outer structure 11 and the inner structure 12 extend, the volume of the working space 18 increases. From this, it is understood that when the working fluid 21 is heated and the liquid phase portion is transferred to the gas phase and the pressure in the working space 18 is increased, the outer structure 11 and the inner structure 12 are expanded accordingly. it can.

  The double-layer bellows structure comprising the outer structure 11 and the inner structure 12 can greatly reduce the mass of the working fluid 21 in the working space 18 compared to a single-layer bellows. The working fluid 21 can be vaporized. Therefore, the vaporization or liquefaction response of the working fluid 21 can be improved, and the extension amount of the outer structure 11 and the inner structure 12 can be increased. This means increasing the operating frequency and amplitude of the drive. Furthermore, since the required working space 18 can be made extremely small compared to the outer structure 11 and the outer structure 12, the outer structure 11 and the inner structure 12 have been increased in size in order to increase the driving amount. Even so, the mass of the working fluid 21 required only needs to be increased slightly. Therefore, a large driving amount can be obtained without significantly increasing the amount of heat (electric power) required for the phase transition of the working fluid 21.

  In the present embodiment, the following temperature setting is performed in order to set the expansion amount and the expansion response speed of the outer structure 11 and the inner structure 12 within a desired range. First, when the working fluid 21 is all liquid at normal temperature (initial state), the axial lengths of the outer structure 11 and the inner structure 12 and the range in which the outer structure 11 and the inner structure 12 do not start plastic deformation. The maximum extension amount is the difference between the axial length and the maximum extension amount. A temperature that extends by a numerical value obtained by multiplying the maximum extension amount by a predetermined constant less than 1 (for example, 0.6) with respect to the length of the initial state is set as the maximum value Tceiling of the temperature T. . On the other hand, a temperature lower than the boiling point of the working fluid 21 by a predetermined temperature (for example, 3 ° C.) is set as the set minimum temperature Tfloor of the temperature T.

  When the working fluid 21 in the initial state is heated by causing the heating elements 31 and 32 to generate heat, vaporization of the working fluid 21 starts from a portion near the heating members 31 and 32 where the temperature rises quickly, and the pressure in the working space 18 rises. The outer structure 11 and the inner structure 12 begin to expand. When the heating is further performed, the working fluid 21 far from the heating elements 31 and 32 starts to vaporize, and the extension of the outer structure 11 and the inner structure 12 further proceeds. When the temperature sensor 451 detects that the temperature has reached Tceiling, the supply of power by the power supply 41 is stopped under the control of the controller 42. Then, the temperature of the working fluid 21 starts to decrease due to natural cooling due to outside air or other influences, and the working fluid 21 that has been lowered to the boiling point is liquefied. Due to the liquefaction of the working fluid 21, the extended outer structure 11 and inner structure 12 begin to contract. When the temperature sensor 451 detects that the temperature of the working fluid 21 has decreased to the set minimum temperature Tfloor, when the power supply 41 starts to supply power, the temperature of the working fluid 21 rises and the temperature of the working fluid 21 reaches the boiling point. When it reaches, the outer structure 11 and the inner structure 12 extend again. By repeating such heating (power supply) → heating stop (power supply stop) → natural cooling → heating → heating stop → natural cooling → heating →..., The outer structure 11 and the inner structure 12 are caused to expand and contract. be able to.

  The operation of the drive device according to the present embodiment will be described in detail with reference to FIG. The operation control flow of the driving device is roughly divided into two depending on whether the working fluid 21 is being heated or naturally cooled. In FIG. 4, steps S110 to S115 indicate operation control during heating, and steps S120 to S125 indicate operation control during natural cooling.

First, operation control for heating the working fluid 21 will be described.
When the operation control is started (step S100), first, the temperature T and the pressure P in the working space 18 are measured by the temperature measuring device 45 and the pressure measuring device 46, and the results are taken into the controller 42 (step S111). ). The measurement of the temperature T and the pressure P and the delivery to the controller 42 are preferably performed continuously, but can also be performed at intervals (for example, 1 millisecond) stored in the controller 42 in advance. The controller 42 determines whether or not the temperature T and the pressure P are higher than the limit temperature Tlimit and the limit pressure Plimit as threshold values (a dangerous value if the temperature T increases further), respectively, and if they are higher (YES in step S112). Then, after the supply of power to the heating elements 31, 32 is stopped (step S130), the operation control is ended (step S131).

  On the other hand, when the temperature T and the pressure P are respectively equal to or lower than the limit temperature Tlimit and the limit pressure Plimit (NO in step S112), the relationship between the temperature T and the pressure P measured next is checked (step S113). Here, if the actuator is operating normally, the pressure P also increases as the temperature T increases, for example, and the two have a predetermined relationship that is not independent of each other. Therefore, by comparing the relationship between the normal temperature T and the pressure P measured in advance and stored in the controller 42 with the relationship between the actually measured temperature T and the pressure P, the measured temperature T and the pressure P are compared. It is possible to determine whether or not the relationship with is normal. Therefore, when the relationship between the measured temperature T and the pressure P deviates greatly beyond a predetermined threshold with respect to the normal relationship stored in the controller 42, it is determined to be abnormal (step S113). YES), after stopping the supply of power to the heating elements 31, 32 (step S130), the operation control is ended (step S131). As a cause of the abnormality, for example, there is a case where the pressure does not increase even when the working fluid is heated because a hole is formed in the bellows.

  On the other hand, when it is determined that the relationship between the measured temperature T and pressure P is normal without exceeding a predetermined threshold with respect to the normal relationship stored in the controller 42 ( It is determined whether or not the operator has performed an end operation (NO in step S113) (step S114). The termination operation can be performed by an input unit (for example, a keyboard or a mouse) 48 connected to the controller 42. If the operator has performed an end operation (YES in step S114), the supply of power to the heating elements 31, 32 is stopped (step S130), and then the process ends (step S131).

  If the operator has not performed the end operation (NO in step S114), it is determined whether or not the temperature T is higher than Tceiling (step S115). If the temperature T is equal to or lower than Tceiling (NO in step S115), power is supplied to the heating elements 31 and 32 (step S110), and the temperature T and the pressure P are measured again by the temperature measuring device 45 and the pressure measuring device 46. (Step S111). On the other hand, when the temperature T is higher than Tceiling (YES in step S115), control for naturally cooling the working fluid 21 (steps S120 to S125) is performed. The electric power supplied to the heating elements 31 and 32 can be, for example, a DC voltage of 30 J / sec. However, the electric power can be supplied with any waveform (for example, rectangular wave, sine wave, pulse). Etc.).

The operation control for naturally cooling the working fluid 21 will be described below.
First, supply of electric power to the heating element is stopped (step S120), the temperature T and pressure P in the working space 18 are measured by the temperature measuring device 45 and the pressure measuring device 46, and the results are taken into the controller 42 ( Step S121). The controller 42 determines whether the temperature T and the pressure P are higher than the limit temperature Tlimit and the limit pressure Plimit, respectively. If they are higher (YES in step S122), the operation control is terminated (step S131).

  On the other hand, when the temperature T and the pressure P are respectively equal to or lower than the limit temperature Tlimit and the limit pressure Plimit (NO in step S122), the relationship between the temperature T and the pressure P measured next is checked (step S123). If the relationship between the measured temperature T and pressure P deviates greatly from the normal relationship stored in the controller 42 beyond a predetermined threshold value, it is determined to be abnormal (YES in step S123). ), And ends the operation control (step S131).

  On the other hand, when it is determined that the relationship between the measured temperature T and pressure P is normal without exceeding a predetermined threshold with respect to the normal relationship stored in the controller 42 ( It is determined whether or not the operator has performed an end operation (NO in step S123) (step S124). The termination operation can be performed by the input unit 48 connected to the controller 42. If the operator has performed a termination operation (YES in step S124), the control is terminated (step S131).

  If the operator has not performed the end operation (NO in step S124), it is determined whether or not the temperature T is higher than the set minimum temperature Tfloor (step S125). When the temperature T is equal to or higher than the set minimum temperature Tfloor (NO in step S125), the power supply to the heating elements 31 and 32 is stopped (step S120), and the temperature T and the pressure measuring device 46 again determine the temperature T. The pressure P is measured (step S121). On the other hand, when the temperature T is lower than the set minimum temperature Tfloor (YES in step S125), control for heating the working fluid 21 (steps S110 to S115) is performed.

  In the drive device of the present embodiment, the operation control of heating or natural cooling is repeated until any one of the above-described end conditions (steps S112, S113, S114, S122, S123, S124) is satisfied. The outer structure 11 and the inner structure 12 expand and contract due to the phase transition.

  The limit temperature Tlimit, limit pressure Plimit, Tceiling, and set minimum temperature Tfloor are preferably determined in advance and stored in the controller 42, but may be changed during operation. Further, in both cases of supplying power to the heating elements 31 and 32 (step S110) and stopping the supply of power (step S120), the supply / stop state until the next operation is performed. Retained.

  Next, control related to the setting of the amount of supplied power for setting the expansion amount of the outer structure 11 and the inner structure 12 to a desired amount will be described with reference to FIG. This control is performed at any time during the operation of the drive device.

  When the control is started (step S200), the temperature T and the pressure P are first measured by the temperature measuring device 45 and the pressure measuring device 46, respectively (step S201), and the result is taken into the controller 42. Here, when the temperature T and the pressure P are higher than the limit temperature Tlimit and the limit pressure Plimit, respectively (YES in step S202), supply of power to the heating elements 31 and 32 is stopped (step S210), and then operation control is performed. Is finished (step S211).

  When the temperature T and the pressure P are respectively equal to or lower than the limit temperature Tlimit and the limit pressure Plimit (NO in step S202), the relationship between the temperature T and the pressure P measured next is checked (step S203). If the relationship between the temperature T and the pressure P is abnormal (YES in step S203), the supply of power to the heating elements 31, 32 is stopped (step S210), and the process ends (step S211).

  On the other hand, when it is determined that the relationship between the measured temperature T and pressure P is normal (NO in step S203), it is determined whether the operator has performed an end operation (step S204). . If the operator has performed an end operation (YES in step S204), the supply of power to the heating elements 31 and 32 is stopped (step S210), and the process ends (step S211).

  If the operator has not finished the operation (NO in step S204), the preset temperature Tset stored in advance in the controller 42 is referred to (step S205). The set temperature Tset is a value set as a temperature necessary for heating the working fluid 21 in order to extend the outer structure 11 and the inner structure 12 by a desired amount.

  Next, the controller 42 compares the set temperature Tset with the measured temperature T, and determines the power amount w so that the temperature T in the working space 18 becomes the set temperature Tset (step S206). The amount w of electric power is supplied to the heating elements 31 and 32 (step S207). Feedback control (proportional control, proportional-integral control, proportional-integral-derivative control, etc.) is preferably used for determining the electric energy w in steps S205 to S207. When the amount of power w is 0 or less, the amount of power w is set to 0, no power is supplied to the heating elements 31 and 32, and the working fluid is naturally cooled.

  After the power is supplied, the temperature T and the pressure P are again measured by the temperature measuring device 45 and the pressure measuring device 46 (step S201). Thereafter, the control is continued until one of the already described termination conditions (steps S202, S203, S204) is satisfied. By repeating such control, the working fluid 21 reaches the set temperature Tset, and the outer structure 11 and the inner structure 12 are extended by a desired amount, and the set force can be exhibited.

  In step S205, the set pressure Pset stored in the controller 42 in advance can be referred to instead of the set temperature Tset or together with the set temperature Tset. The set pressure Pset is a value set as a pressure necessary to expand the outer structure 11 and the inner structure 12 by a desired amount, similarly to the set temperature Tset. In this case, the controller 42 compares the set pressure Pset with the measured pressure P, and determines the power amount w so that the pressure P in the working space 18 becomes the set pressure Pset (step S206). The power of w is supplied to the heating elements 31 and 32 (step S207) in the same manner as the control by the set temperature Tset described above.

  In addition, the set temperature Tset and the set pressure Pset are preferably determined in advance before operating the driving device, but may be changed during the operation. Further, when power supply / stop to the heating elements 31 and 32 is performed (step S207), the supply / stop state is maintained until these operations are performed next time.

  Although the present invention has been described with reference to the above embodiment, the present invention is not limited to the above embodiment, and can be improved or modified within the scope of the purpose of the improvement or the idea of the present invention.

It is the partial longitudinal cross-sectional view which showed the structure of the drive device which concerns on embodiment of this invention, and showed the internal structure of the outer side structure and the inner side structure. It is sectional drawing along the II-II line in FIG. (A) is a conceptual diagram which shows the state which the outer structure and inner structure which concern on embodiment of this invention contracted, (b) is a conceptual diagram which shows the state which the outer structure and inner structure extended | stretched. . It is a flowchart which shows the flow of operation control of the drive device which concerns on embodiment of this invention. It is a flowchart which shows the flow of operation control of the drive device which concerns on embodiment of this invention.

Explanation of symbols

11 outer structure 11a peak 11b valley 12 inner structure 12a peak 12b valley 15 sealing plate 16 sealing plate 18 working space 21 working fluid 31 heating element (heater)
32 Heating element (heater)
35 Shape Retaining Ring 36 Shape Retaining Ring 41 Power Supply 42 Controller 45 Temperature Measuring Device 46 Pressure Measuring Device 131 Heating Element 132 Heating Element Plimit Limit Pressure Pset Set Pressure Tfloor Set Minimum Temperature Tceiling Set Maximum Temperature Tlimit Limit Temperature Tset Set Temperature

Claims (7)

A stretchable hollow outer structure;
A retractable hollow inner structure housed inside the outer structure and forming an operating space with the outer structure;
A working fluid enclosed in a working space between the outer structure and the inner structure;
A heating element provided in a layered manner on at least one of the inner surface of the outer structure and the outer surface of the inner structure in the working space;
A shape retaining ring fitted into the outer surface of the outer structure and the inner surface of the inner structure outside the working space,
By heating the working fluid by generating heat from the layered heating element, the working fluid is transferred from the liquid phase to the gas phase to increase the pressure in the working space, and the outer structure and the inner structure A driving device characterized in that the device is extended. The driving device according to claim 1, wherein the layered heating element is provided on each of an inner surface of the outer structure and an outer surface of the inner structure in the working space. The diameter of the shape retaining ring fitted on the outer surface of the outer structure is set so that the working fluid contacts the outer surface of the outer structure when the working fluid is in a liquid phase lower than its boiling point. 3. The drive device according to claim 1, wherein a diameter of the shape retaining ring fitted into the inner surface of the inner surface of the inner structure is set so as to abut on the inner surface of the inner structure when the working fluid is in a liquid phase lower than its boiling point. . 4. The driving device according to claim 1, wherein the outer structure body and the inner structure body have a bellows shape in which a plurality of peaks and valleys are formed at a constant interval. 5. The driving device according to claim 4, wherein the shape retaining ring is fitted into an outer side of the valley portion of the outer structure body and an inner side of the mountain portion of the inner structure body. The drive device according to claim 4 or 5, wherein the outer structure and the inner structure have the same pitch between the crests and the troughs. The driving device according to claim 1, wherein the outer structure and the inner structure are made of an elastic material .

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