Air actuator

Abstract

Air actuators contract and extend through intake and exhaustion of air, but since the air is exhausted only by internal pressure, air exhaustion takes longer than air intake, and high-speed contraction and extension operation cannot be performed.　The present invention addresses this problem by providing an air actuator including: a cylindrical frame in which a stopper is provided on an inner wall on one end side and the other end side is closed by a closing lid; a bag-shaped elastic body having a bag opening which is fixed to an end portion on the one end side of the cylindrical frame; an end pin which is disposed in the cylindrical frame, has a surface on the bag-shaped elastic body side and a surface on the closing lid side, is provided with a through-hole penetrating through the surface on the bag-shaped elastic body side and the surface on the closing lid side, and a gauge valve on the surface side on the bag-shaped elastic body side of the through-hole, the end pin being movable inside the cylindrical frame; an air passage which is provided in a side surface of the cylindrical frame and which is closed when the end pin abuts the stopper; and an air intake / exhaust pipe which is provided in the closing lid and which provides communication between the inside and the outside of the cylindrical frame. The air actuator can perform exhaust at once, and has excellent high-speed response.

Description

Air actuator 【0001】 The present invention relates to an air actuator that can be used for artificial muscles and the like. 【0002】 The driving of an air actuator used in a pneumatic rubber artificial muscle or the like increases the exerted force (output) by increasing the pressure inside the air actuator, and decreases the exerted force by decreasing the pressure. Generally, when decreasing the pressure, air is discharged through an air supply and exhaust pipe to a tank that controls the pressure of the air inside the air actuator (artificial muscle). However, the force to push out the air at this time depends on the pressure difference between the pressure inside the air actuator and the pressure inside the tank (control amount), and it cannot be easily increased (improved decompression speed). If the limit of the decompression speed is determined, the responsiveness of the device when the air actuators are arranged antagonistically cannot be increased, and there is a problem that the control performance is limited. 【0003】 In response to such problems, Patent Document 1 proposes a method that, by combining with an electric motor, performs fast feedback control with high responsiveness and enables position and force control that is difficult with only an air actuator (pneumatic artificial muscle) with poor responsiveness. 【0004】 Japanese Unexamined Patent Application Publication No. 2023 - 034376 【0005】 With the method of Patent Document 1, precise position and force control may be possible. However, since an electric motor is required, there is a problem that the overall weight increases because members such as the electric motor and the connecting mechanism between the electric motor and the air actuator are required. 【0006】 The present invention was conceived in view of the above problems, and provides an air actuator that is highly responsive and lightweight by using only air flow control for the air actuator. 【0007】More specifically, the air actuator according to the present invention comprises: a cylindrical frame (14) having a stopper (14g) on ​​the inner wall of one end and the other end closed with a closing lid (14c); a bag-shaped elastic body (10) having a bag opening (10a) fixed to the end of the cylindrical frame (14); an end pin (16) disposed inside the cylindrical frame (14), having a surface (16b) on the bag-shaped elastic body side and a surface (16a) on the closing lid side, a through hole (16h) penetrating the surface (16b) on the bag-shaped elastic body side and the closing lid side (16a); a gauge valve (18) provided on the surface (16b) of the through hole (16h), and an end pin (16) movable inside the cylindrical frame (14); The cylindrical frame is characterized by having an air passage (14h) provided on the side surface (14s) of the cylindrical frame, which is closed when the end pin (16) comes into contact with the stopper (14g), and an air supply and exhaust pipe (22) provided on the closing lid (14c) that connects the inside and outside of the cylindrical frame (14). 【0008】 The air actuator according to the present invention has an end pin that is movable within a cylindrical frame and has a gauge valve on the side of a bag-shaped elastic body, and a drive space D formed between the end pin and a closing lid that can adjust the air pressure. The cylindrical frame is provided with an air passage with a larger cross-sectional area than an air supply / exhaust pipe that communicates with the outside air when the end pin moves toward the side of the bag-shaped elastic body. As a result, when the pressure is reduced, the bag-shaped elastic body communicates with the atmosphere through the air passage, and the air inside the bag-shaped elastic body can be rapidly exhausted. This can be described as a rapid exhaust mechanism that switches the flow path between pressurized and depressurized states. 【0009】 Furthermore, since this rapid exhaust mechanism operates using the pressure difference between the drive space D created between the closing lid and the end pin and the bag-shaped elastic body, no special power source such as a motor is required for switching the intake and exhaust flow paths, contributing to the overall weight reduction of the system. 【0010】These are conceptual diagrams (a) and assembly diagrams (b) of a cross-section of the air actuator according to the present invention. Conceptual diagram (a) shows the state before air is introduced into the air actuator, and conceptual diagram (b) shows the state when air has started to flow in. Conceptual diagram (a) shows the state when air is introduced into the bag-shaped elastic body, and conceptual diagram (b) shows the state when more air is introduced and the bag-shaped elastic body expands. Conceptual diagram (a) shows the state when the inflow of air is stopped, and conceptual diagram (b) shows the state when air is removed from the drive space D and the end pin retracts, opening the air passage and rapidly releasing the air inside the bag-shaped elastic body. This is a diagram showing an example in which an O-ring is placed on the side of the end pin to improve the airtightness of the drive space D. Conceptual diagram (a) shows the state before air is introduced, and conceptual diagram (b) shows the state when air is introduced and the end pin is in contact with the end cap. Conceptual diagrams (a) and assembly diagrams (b) of a cross-section when a bellows is used to form the drive space instead of the sealed section D. Conceptual diagram (a) shows the state in which air begins to enter the bellows, and conceptual diagram (b) shows the state in which the end pin hits the end cap and the bellows expands. Conceptual diagram (a) shows the state in which the pressure inside the bellows exceeds a certain pressure, air enters the bag-shaped elastic body and the bag-shaped elastic body expands, and the injection of air is stopped, and conceptual diagram (b) shows the state in which the bag-shaped elastic body contracts and the air inside the bag-shaped elastic body is rapidly discharged from the air passage. Conceptual diagram showing the state in which the end pin hits the end cap, the pressure inside the bellows exceeds the back pressure of the gauge valve and air is supplied to the bag-shaped elastic body. This is a graph showing the relationship between time and pressure in an embodiment of the air actuator according to the present invention. This is a graph showing the relationship between time and amount of movement in an embodiment of the air actuator according to the present invention. 【0011】 The air actuator according to the present invention will be described below with reference to the drawings. The following description illustrates one embodiment of the present invention and one example, and the present invention is not limited to the following description. The following description may be modified without departing from the spirit of the present invention. Furthermore, all references cited herein are incorporated herein by reference. 【0012】Furthermore, in the following explanation, the side on the drawing where the bag-shaped elastic body 10 is located (right side) will be referred to as the operating side, and the side where the closing lid 14c is located (left side) will be referred to as the driving side. Also, the direction from left to right in the drawing will be referred to as the operating side direction, and the direction from right to left will be referred to as the driving side direction. The operating side may also be referred to as the one-end side, and the driving side as the other-end side. Of course, the one-end side and the operating side may be referred to as the bag-shaped elastic body side, and the other-end side and the driving side as the closing lid side, or the operating side direction may be referred to as the one-end side direction, and the driving side direction as the other-end side direction. 【0013】 <First Embodiment> <Configuration> Figure 1 shows the configuration of the air actuator according to the present invention. Figure 1(a) is a conceptual cross-sectional view of the air actuator 1, and Figure 1(b) is an assembly view thereof. The air actuator 1 consists of a bag-shaped elastic body 10, a cylindrical frame 14, an end pin 16, a gauge valve 18, and a closing lid 14c. The air actuator 1 may also include a cylindrical braided body 30 that expands radially and simultaneously contracts longitudinally on the outer surface side of the bag-shaped elastic body 10, and an end member 32. The cylindrical braided body 30 is connected to the end cap 12 and the end member 32. The circular braided body 30 may also be fixed to the end of the cylindrical frame 14 on the bag-shaped elastic body 10 side. 【0014】 The bag-shaped elastic body 10 is the muscle portion of the air actuator 1. A rubber tube with a length of 10L and a diameter of 10φ is preferably used. One end of the bag-shaped elastic body 10 (the operating end) is a closed end. The other end of the bag-shaped elastic body 10 (the driving end) is the bag opening 10a. The bag opening 10a is an air inlet through which air enters the bag-shaped elastic body 10. The bag opening 10a of the bag-shaped elastic body 10 is fixed so as to close the one end which is the open end of the cylindrical frame 14. 【0015】 The method of fixing the bag-shaped elastic body 10 to the cylindrical frame 14 is not particularly limited, and it may be fixed directly to the cylindrical frame 14. However, the bag opening 10a may be fixed in advance to an end cap 12 that can be fitted into the inner wall 14i of the cylindrical frame 14, and the end cap 12 may be fitted into the cylindrical frame 14 to fix it in place. 【0016】The braided cord 30 is made by braiding fibers into a tubular shape. The fibers themselves do not stretch, but when the braided cord 30 is pulled in the length direction, it stretches in the length direction while decreasing its inner diameter. Conversely, when it is expanded in the diameter direction, it shrinks in the length direction while increasing its inner diameter. 【0017】 The end member 32 is for securing the end of the braided body 30. The braided body 30 only needs to have one end secured. In other words, even without using a special member like the end member 32, one end of the braided body 30 can be sealed and secured to form a bag shape. 【0018】 The end cap 12 is a cylindrical member, and its inner wall is airtightly connected to the outer wall of the bag-shaped elastic body 10. Here, "airtightly connected" means that no air leaks at the point of connection. The same meaning is used for "airtightly connected" in the following explanation. 【0019】 The side 12a of the end cap 12 opposite to the bag-shaped elastic body 10 (the drive side (other end side) side 12a) should be finished flat so as to be free of burrs or other debris. This is to prevent air leakage when it comes into contact with the end pin 16, which will be described later. 【0020】 The cylindrical frame 14 has a cylindrical shape with a circular cross-section. A stopper 14g, which is convex toward the inside of the cylinder, is provided on the inner wall 14i at one end of the cylindrical frame 14. An air passage 14h is provided on the other end of the cylindrical frame 14, which connects the inside and outside of the cylindrical frame 14. The shape of the air passage 14h is not particularly limited, but it should have a cross-sectional area large enough to allow the air accumulated in the bag-shaped elastic body 10 to be released all at once, as will be described later. It should have a cross-sectional area at least larger than the cross-sectional area of ​​the air supply and exhaust pipe 22, which will be described later. 【0021】 The end cap 12 is fixed to one end of the cylindrical frame 14. The fixing method is not particularly limited, but it is preferable that it be fixed airtightly between the inside of the cylindrical frame 14 and the bag-shaped elastic body 10. For example, a preferred method is to cut a female thread on the inside of one end of the cylindrical frame 14, cut a male thread on the side surface 16s of the end cap 12, and screw the end cap 12 onto the cylindrical frame 14 with a shielding tape (not shown) in between. 【0022】 As shown in the embodiment described later (the second embodiment), a radially convex return 14tg may be provided on the inner wall 14i of one end of the cylindrical frame 14 to prevent the end cap 12 from protruding from the inside of the cylindrical frame 14 toward the one end. 【0023】 The end pin 16 is a cylindrical member positioned inside the cylindrical frame 14 and having a surface 16b at one end and a surface 16a at the other end. The end pin 16 is configured to move within the cylindrical frame 14 from a position separated from the end cap 12 to a position where it presses against (contacts) the stopper 14g, with the side surface 16s of the end pin 16 facing the inner wall 14i of the cylindrical frame 14. 【0024】 The position where the end pin 16 is separated from the end cap 12 is such that the side surface 16s of the end pin 16 does not cover the air passage 14h of the cylindrical frame 14. On the other hand, the side surface 16s of the end pin 16 has a thickness 16L such that it covers the air passage 14h when the end pin 16 comes into contact with the stopper 14g. 【0025】 The end pin 16 has a through hole 16h formed therein, extending from one end surface 16b to the other end surface 16a. 【0026】 A gauge valve 18 is airtightly joined to the surface 16b of one end of the through hole 16h of the end pin 16. When the air pressure from the other end surface 16a to the one end surface 16b of the end pin 16 exceeds a certain value 18Th, the valve opens and allows air to pass through. On the other hand, no air flows from the one end surface 16b to the other end surface 16a. The certain value 18Th is the threshold at which the gauge valve 18 opens. 【0027】The closing lid 14c is a lid that airtightly seals the other end of the cylindrical frame 14. However, the closing lid 14c is provided with an air supply and exhaust pipe 22 that connects the inside and outside of the cylindrical frame 14. The space enclosed by the closing lid 14c, the other end surface 16a of the end pin 16, and the inner wall 14i of the cylindrical frame 14 is the drive space D. Air can enter and exit the drive space D through the air supply and exhaust pipe 22. Note that the closing lid 14c may be a separate component from the cylindrical frame 14 and joined to the cylindrical frame 14 by adhesive, or it may be integrally molded at the same time as the cylindrical frame 14 is manufactured. 【0028】 An air supply device (not shown) is connected to the air intake / exhaust pipe 22. Compressed air from this air supply device flows into the drive space D. The compressed air also increases the air pressure DP in the drive space D after the end pin 16 contacts the stopper 14g. On the other hand, if the air supply device leaks, the air in the drive space D flows out through the air intake / exhaust pipe 22, and the air pressure DP in the drive space D decreases to atmospheric pressure. 【0029】 <Operation Description> Next, the operation of the air actuator 1 will be described. Figure 2(a) shows the state before air is injected from the air supply and exhaust pipe 22, that is, before the air actuator 1 is in operation, and Figure 2(b) shows the state when the air actuator 1 has started to operate. Referring to Figure 2(a), before air pressure is applied to the end pin 16, the end pin 16 is retracted to the other end of the cylindrical frame 14, and the air passage 14h of the cylindrical frame 14 is in communication with the outside air inside the bag-shaped elastic body 10. 【0030】 Referring to Figure 2(b), when air is introduced through the air intake / exhaust pipe 22, the air actuator 1 operates. When air pressure is applied from the other end of the end pin 16 toward the one end, the end pin 16 moves toward the one end inside the cylindrical frame 14. The end pin 16 comes into contact with the stopper 14g and stops moving. At that time, the side surface 16s of the end pin 16 blocks the air passage 14h of the cylindrical frame 14. As a result, the inside of the bag-shaped elastic body 10 becomes airtight. 【0031】Refer to Figure 3. Figure 3(a) shows the state after more air has flowed into the drive space D from Figure 2(b). The air pressure DP in the drive space D increases. When the air pressure DP exceeds a certain value 18Th, the gauge valve 18 opens, and air also enters the bag-shaped elastic body 10. 【0032】 Figure 3(b) shows the state in which air is contained within the bag-shaped elastic body 10. The bag-shaped elastic body 10 expands with the air from the gauge valve 18. However, the braided body 30 and the end member 32 restrict its extension toward one end. As a result, the bag-shaped elastic body 10 expands radially. This radial expansion reduces the length 10L of the bag-shaped elastic body 10. This reduced length FL becomes the amount of movement of the air actuator. 【0033】 Refer to Figure 4. Figure 4(a) shows the state when the air inflow into the drive space D has stopped. When the air inflow into the drive space D stops, the air inflow from the gauge valve 18 into the bag-shaped elastic body 10 stops. Then, due to the contraction force of the bag-shaped elastic body 10, a pressure fv is applied to the end pin 16 in the direction of the other end. However, the pressure in the drive space D and the pressure in the bag-shaped elastic body 10 are in equilibrium, and the operation of the air actuator 1 stops in the state shown in Figure 4(a). 【0034】 Next, refer to Figure 4(b). Figure 4(b) shows the state in which air is discharged from the air intake / exhaust pipe 22. When air is discharged from the drive space D, the air pressure DP in the drive space D decreases, and the pressure pushing the end pin 16 decreases. The pressure fv pushing the end pin 16 from the bag-shaped elastic body 10 becomes higher than the force pushing the end pin 16 from the drive space D, so the end pin 16 moves to one end. Then, when the end pin 16 moves away from the position that blocks the air passage 14h, the air passage 14h and the inside of the bag-shaped elastic body 10 become connected, and the air inside the bag-shaped elastic body 10 is suddenly released to the outside. 【0035】Generally, compressed air can be supplied to the bag-shaped elastic body 10 through the drive space D in a short time. However, when removing the supplied air, the cross-sectional area of ​​the air supply / exhaust pipe 22 becomes the rate-limiting condition, making it difficult to shorten the exhaust time. The air actuator 1 according to the present invention makes it possible to shorten the exhaust time to an extremely short time when removing air from the bag-shaped elastic body 10 by opening an air passage (total cross-sectional area of ​​the air passage 14h) that is larger than the air passage (cross-sectional area of ​​the air supply / exhaust pipe 22) used for supplying air. 【0036】 Figure 5 shows a modified example of the first embodiment. Figure 5(a) shows the state before air is injected into the drive space D (the air actuator 1 is not operating), and Figure 5(b) shows the state when the air actuator 1 is operating. In this embodiment, a return 14tg is provided at one end of the cylindrical frame 14 in order to fix the end cap 12 to which the bag-shaped elastic body 10 is fixed inside the cylindrical frame 14. That is, the surface 12b at one end of the end cap 12 abuts against the return 14tg, so that the end cap 12 does not protrude from inside the cylindrical frame 14 toward the one end. 【0037】 Furthermore, an O-ring groove 16d is provided on the side surface 16s of the end pin 16, and an O-ring 40 is provided. The O-ring 40 further improves the airtightness of the drive space D, and increases the operating efficiency of the air actuator 1. Here, operating efficiency can be evaluated by the amount of air injected from the air supply and exhaust pipe 22, the operating speed of the air actuator 1, and the holding time when the operation is stopped (see Figure 4(a)). Note that methods other than O-rings are acceptable as long as airtightness is ensured between the side surface 16s of the end pin 16 and the inner wall 14i of the cylindrical frame 14. For example, a high-viscosity oil may be placed between the end pin 16 and the cylindrical frame 14. These means of improving the airtightness of the drive space D are called "shields". 【0038】 Referring to Figure 5(b), the end pin 16 stops moving when it comes into contact with the end face 12a of one end of the end cap 12. Therefore, the end cap 12 can be considered a stopper 14g. 【0039】Furthermore, when the end pin 16 comes into contact with the stopper 14g and becomes unable to move, it is preferable that the O-ring 40 is configured so that it does not come into contact with the air passage 14h. This is because if the O-ring 40 comes into contact with the air passage 14h, the movement of the end pin 16 will be hindered by the snagging. Therefore, referring to Figure 5(b), it is preferable that the O-ring 40 and the air passage 14h be configured such that when the end pin 16 comes into contact with the stopper 14g, the O-ring 40 is on one end side of the air passage 14h. 【0040】 <Second Embodiment> <Configuration> Figure 6 shows the configuration of the air actuator 2 according to this embodiment. Figure 6(a) is a conceptual cross-sectional view of the air actuator 2, and Figure 6(b) is an assembly view thereof. The air actuator 2 differs from the air actuator 1 of Embodiment 1 in that a bellows 26 is used in the drive space D, and a ventilation pipe 16hp is installed through the through hole 16h of the end pin 16. 【0041】 By using the vent pipe 16hp, the gauge valve 18 can be positioned further inside the bag-shaped elastic body 10. In particular, when the length 10L of the bag-shaped elastic body 10 is long, positioning the gauge valve 18 closer to the center of the bag-shaped elastic body 10 allows for more uniform pressure rise between one end (end pin 16 side) and the other end (end member 32 side), making it easier to improve the response speed of the air actuator. 【0042】 In the air actuator 2, the drive space D is composed of a bellows 26. By using the bellows 26, the airtightness of the space composed of the end pin 16, the closing lid 14c, and the inner wall 14i of the cylindrical frame 14 can be reduced. In other words, the cylindrical frame 14 itself can be lightened, making the air actuator 2 as a whole lighter. 【0043】 The bellows 26 is airtightly joined to the air supply and exhaust pipe 22 at its other end 26a (opposite the bag-shaped elastic body 10). An air supply and exhaust source (not shown) is connected to the air supply and exhaust pipe 22. The bellows 26 is fixed inside the cylindrical frame 14 so as not to hinder the expansion and contraction of the bellows 26. 【0044】In FIG. 6, the cylindrical frame 14 has a closing lid 14c to which an air supply and exhaust pipe 22 is airtightly joined at the other end side 14a (the side opposite to the side where the bag-shaped elastic body 10 is disposed), and the other end side 26a of the bellows 26 (the side opposite to the side where the bag-shaped elastic body 10 is disposed) is shown in a state of being airtightly fixed to the air supply and exhaust pipe 22. Also, one end side 26b of the bellows 26 is airtightly fixed to the ventilation pipe 16hp of the end pin 16. 【0045】 The inner diameter cross-sectional area of the air supply and exhaust pipe 22 is smaller than the cross-sectional area of the air passage 14h of the cylindrical frame 14. This is for increasing the exhaust speed during exhaust, as will be described later. 【0046】 <Operation Explanation> Next, the operation of the air actuator 2 will be described. FIG. 7(a) shows the state before air is supplied to the air actuator 2, and FIG. 7(b) shows the state where air supply has started. Referring to FIG. 7(a), the bellows 26 is in a contracted state, and the end cap 12 and the end pin 16 are separated. In this state, when air Air is supplied from an air supply source (for example, a compressor), the air is injected into the bellows 26. 【0047】 The air also flows into the ventilation pipe 16hp, but since the air is not allowed to pass through the gauge valve 18 until the ventilation pipe 16hp reaches a certain value 18Th, air accumulates in the bellows 26. As the air accumulates, the bellows 26 expands in the direction of one end side, pushing the end pin 16 toward the end cap 12 side. As a result, the end pin 16 moves toward the end cap 12 and abuts against the end cap 12 (FIG. 7(b)). At this time, the side surface 16s of the end pin 16 closes the air passage 14h. As a result, the bag-shaped elastic body 10 becomes airtight. 【0048】 Referring to FIG. 8(a), when the end pin 16 hits against the end cap 12, the end pin 16 cannot move further inside the cylindrical frame 14. Therefore, the pressure inside the bellows 26 increases. When the pressure inside the bellows 26 exceeds a certain value 18Th, the gauge valve 18 opens, and the bag-shaped elastic body 10 is filled with air. The filled air expands the bag-shaped elastic body 10. 【0049】A braided cord 30 is positioned on the outside of the bag-shaped elastic body 10, with one end restrained by an end member 32, preventing the bag-shaped elastic body 10 from stretching in the direction of one end. As a result, as the bag-shaped elastic body 10 expands, it expands radially, generating a force F that causes the entire air actuator 2 to contract. In other words, the air actuator 2 becomes operational. The operation of this part is the same as in the first embodiment, except that the drive space D is replaced by a bellows 26. 【0050】 Referring to Figure 9, the pressure-receiving area A1 of the bellows 26 is the cross-sectional area of ​​the bulging belly of the bellows 26 (indicated by arrow A1), and the pressure-receiving area A2 on the bag-shaped elastic body 10 side is the inner diameter of the bag-shaped elastic body 10 (indicated by arrow A2). By setting the relationship A1 > A2, the bag-shaped elastic body 10 can be expanded until the pressure inside the bellows 26 and the pressure inside the bag-shaped elastic body 10 become equal. Furthermore, when supplying air Air from the air supply / exhaust pipe 22 into the bellows 26, a pressure pump or the like can be used to rapidly supply air at high pressure. 【0051】 Returning to Figure 8, and also referring to Figures 3 and 4, referring to Figure 8(a), when the supply of air to the air intake / exhaust pipe 22 is stopped, the inflow of air into the bag-shaped elastic body 10 stops. However, the gauge valve 18 prevents the movement of air from inside the bag-shaped elastic body 10 to the bellows 26, and since the pressure inside the bellows 26 and the pressure inside the bag-shaped elastic body 10 are balanced, the end pin 16 remains pressed against the end cap 12. 【0052】 Next, when air is drawn out of the air intake / exhaust pipe 22, or when one end 22a of the air intake / exhaust pipe 22 is opened, the air inside the bellows 26 escapes, and the bellows 26 contracts. The pressure inside the bellows 26 becomes lower than the pressure inside the bag-shaped elastic body 10, and the end pin 16 moves in a direction away from the bag-shaped elastic body 10. 【0053】When a gap forms between the end pin 16 and the end cap 12, the air inside the bag-shaped elastic body 10 is rapidly discharged through the air passage 14h provided on the side surface 14s of the cylindrical frame 14, further pushing the end pin 16 toward the air supply / exhaust pipe 22. As a result, the bag-shaped elastic body 10 rapidly contracts, the air actuator 2 extends in length, and the longitudinal force F disappears. 【0054】 The discharge time in this case can be shortened if the cross-sectional area of ​​the air passage 14h of the cylindrical frame 14 is larger than the cross-sectional area of ​​the air supply and exhaust pipe 22. 【0055】 Air actuators of Normal, Type 1, and Type 2 were fabricated using the specifications in Table 1, and operational experiments were conducted. The Normal type does not have an air passage 14h on the side of the cylindrical frame 14. Air injected into the bag-shaped elastic body 10 is discharged to the outside only through the air supply pipe 22 into which the air is supplied. Type 1 is a bellows type and is shown in the second embodiment. Type 1 is a cylinder type and is shown in Figure 5 of the first embodiment. In other words, an O-ring 40 is fixed to the side of the end pin 16. 【0056】 【0057】 The experiment was conducted using the following procedure: (1) Compressed air generated by a compressor was depressurized using an electro-pneumatic regulator and pre-filled into a 0.3L tank. (2) A 3-port valve was connected between the 0.3L tank and the air accumulator, and the 3-port valve was driven in a 2-second cycle of 1 second ON and 1 second OFF. During the OFF period, the air supply pipe 22 was open to the atmosphere. This OFF period is referred to as "leaking the air supply pipe 22". (3) The air accumulator tube was filled with 100 kPa for 1 second and released for 1 second. Displacement and pressure data were obtained for each type of air accumulator. 【0058】 The results are shown in Figures 10 and 11. In Figure 10, the horizontal axis represents time (s) and the vertical axis represents the pressure (kPa) inside the bag-shaped elastic body 10. In Figure 11, the horizontal axis represents time (s) and the vertical axis represents the amount of movement, which is the reduction length FL (m). The reduction length is defined as "Displacement". 【0059】Referring to Figure 10, Normal is represented by a solid line, Type 1 (bellows type) by a dotted line, and Type 2 (cylinder type) by a dashed line. The Normal type, which lacks a gauge valve, showed superior pressure rise within the bag-shaped elastic body 10. However, when the air supply pipe 22 was leaked, the pressure within the bag-shaped elastic body 10 in both the Type 1 and Type 2 samples became almost zero within 0.1 seconds. On the other hand, the Normal type took longer to decrease in pressure, and especially after falling below 10 kPa, the rate of pressure decrease slowed down, and it took approximately 0.7 seconds from the time of leaking for the pressure to reach zero. 【0060】 Referring to Figure 11, the Normal is represented by a solid line, Type 1 (bellows type) by a dotted line, and Type 2 (cylinder type) by a dashed line, just as in Figure 10. Figure 11 can be said to represent the operating response of the air actuator. The reduction amount FL for all samples was 0.0 m (6 cm). First, the rise time was almost the same for all samples: Normal, Type 1, and Type 2. On the other hand, when leaked, the extension speed of Type 1 and Type 2 was approximately 0.1 seconds. This indicates that the air actuator was operating instantaneously. In contrast, it took 0.5 seconds for the Normal to extend after leaking. 【0061】 Table 1 shows the ratio of the cross-sectional area of ​​the air passage 14h to the cross-sectional area of ​​the air supply pipe 22. Based on the results of the above experiment, it can be said that a ratio of 20 to 32 times the cross-sectional area of ​​the air passage 14h to the cross-sectional area of ​​the air supply pipe 22 is within a range in which operation is suitably possible. 【0062】 As described above, in the air actuator according to the present invention, the cross-sectional area of ​​the main ventilation path during air discharge is larger than the cross-sectional area of ​​the ventilation path during air injection into the bag-shaped elastic body 10. Therefore, the air stored in the bag-shaped elastic body 10 is discharged at high speed, and contraction can be performed at high speed. Furthermore, since the above mechanism switches the main ventilation path during air discharge from the cross-sectional area of ​​the ventilation path during air injection using only the supply and exhaust of air from the air supply and exhaust pipe 22, an electrical drive such as a motor is unnecessary, thus contributing to the weight reduction of the air actuator. 【0063】The air actuator according to the present invention is small and not bulky, making it suitable for use in environments such as small robots and wearable devices. 【0064】 1, 2 Air Actuator 10 Bag-shaped elastic body 10L Length (of the bag-shaped elastic body) 10φ Diameter (of the bag-shaped elastic body) 10a Air inlet (bag opening) 12 End cap 12a Face of the other end of the end cap 12b Face of one end of the end cap 14 Cylindrical frame 14s Side of the cylindrical frame 14h Air passage 14a Other end 14c Closure lid 14g Stopper 14i Inner wall (of the cylindrical frame) 14tg Return 16 End pin 16a Face of the other end (of the end pin) 16b Face of one end (of the end pin) 16d O-ring groove 16s Side of the end pin 16h Through hole 16hp Vent tubing 16L Thickness (of the end pin 16) 18 Gauge valve 18Th Constant value (threshold pressure to open the gauge valve) 26 Bellows 22 Air supply / exhaust pipe 30 Braided body 32 End member 40 O-ring D Drive space DP Air pressure FL Reduced length fv Pressure

Claims

1. An air actuator comprising: a cylindrical frame having a stopper on the inner wall of one end and the other end closed with a closure lid; a bag-shaped elastic body having a bag opening fixed to the end of the cylindrical frame at one end; an end pin disposed inside the cylindrical frame, having a surface on the bag-shaped elastic body side and a surface on the closure lid side, a through hole penetrating the surface on the bag-shaped elastic body side and the surface on the closure lid side, and a gauge valve provided on the surface of the through hole on the surface on the bag-shaped elastic body side, and movable inside the cylindrical frame; an air passage provided on the side of the cylindrical frame, which is closed when the end pin comes into contact with the stopper; and an air supply and exhaust pipe provided on the closure lid, which connects the inside and outside of the cylindrical frame.

2. The air actuator according to claim 1, wherein the cross-sectional area of ​​the air passage is greater than the cross-sectional area of ​​the air supply and exhaust pipe.

3. The air actuator according to claim 1 or 2, having a shield that airtightly holds the side surface of the end pin and the inner wall of the cylindrical frame.

4. The air actuator according to claim 2, wherein the shield is positioned on the closing lid side of the air passage when the end pin contacts the stopper.

5. The air actuator according to claim 1 or 2, wherein a bellows is positioned between the end pin and the closing lid, the air intake / exhaust pipe is in communication with the bellows, and the closing lid side of the through hole is in communication with the bellows.

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