Artificial muscle actuator device

Abstract

To provide an artificial muscle actuator device excellent in responsiveness and capable of continuous driving.SOLUTION: An artificial muscle actuator includes: an elastic cylindrical part forming a combustion chamber; a cover member closing both ends of the elastic cylindrical part and forming the combustion chamber with the elastic cylindrical part; an elastic cylindrical part facing the combustion chamber and an elastic cylindrical part closing both ends of the elastic cylindrical part; an ignition device for igniting a mixture of fuel and air in the combustion chamber; a restraining member for restraining the elastic cylindrical part such that the elastic cylindrical part deforms in an axial direction by expansion of combustion gas in the combustion chamber; and a vent for constantly communicating the combustion chamber with an external space. An artificial muscle actuator device includes: the artificial muscle actuator; a mixture supply device for supplying the mixture to the combustion chamber; and an ignition control device for controlling ignition of the ignition device. The ignition control device performs ignition in a state where the mixture is supplied from the mixture supply device into the combustion chamber.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a device for driving an artificial muscle actuator.

Background Art

[0002] Conventionally, for the purpose of driving a body-worn walking assistance device or an assist device, for example, an artificial muscle actuator that operates by air pressure as disclosed in Patent Document 1 has been used. An actuator driven by air pressure has problems of low responsiveness while being lightweight, high-output, excellent in flexibility, and having high affinity with humans. For driving such an actuator, supply of compressed air is required. However, since air itself has compressibility, it is one of the factors causing response delay. Due to such response delay, generation of displacement and force is delayed, causing difficulty in performing instantaneous operations. As a method for solving such response delay of an air pressure-driven actuator, for example, as disclosed in Patent Document 2, a method has been proposed in which a mixture of fuel and air is supplied instead of compressed air, and the mixture is burned by igniting the mixture, and the actuator is driven by the expansion of the combustion gas.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, although the driving method disclosed in Patent Document 2 improves the responsiveness of a conventional air pressure-driven actuator by generating a large instantaneous force by combustion, problems remain in continuous driving. Therefore, an object of the present invention is to provide an artificial muscle actuator device that is excellent in responsiveness and enables continuous driving.

Means for Solving the Problems

[0005] As a configuration of the artificial muscle actuator device for solving the above problems, an elastic cylinder portion forming a combustion chamber, a lid member closing both ends of the elastic cylinder portion and forming a combustion chamber together with the elastic cylinder portion, an elastic cylinder portion facing the combustion chamber and an elastic cylinder portion closing both ends of the elastic cylinder portion, an ignition device for igniting an air-fuel mixture in the combustion chamber, a restraint member for restraining the elastic cylinder portion so that the elastic cylinder portion is deformed in the axial direction by the expansion of the combustion gas in the combustion chamber, a ventilation port for constantly communicating the combustion chamber with the external space, an artificial muscle actuator having, a mixture supply device for supplying a mixture to the combustion chamber, and an ignition control device for controlling the ignition of the ignition device, and the ignition control device is configured to ignite in a state where the mixture is being supplied from the mixture supply device into the combustion chamber. According to this configuration, the artificial muscle actuator can be made to enable continuous driving with excellent responsiveness. Further, as another configuration of the artificial muscle actuator device, a plurality of the artificial muscle actuators are provided, the mixture supply device is capable of supplying a mixture to the plurality of artificial muscle actuators, and the ignition control device is configured to be capable of selectively igniting the ignition devices of the plurality of artificial muscle actuators. According to this configuration, while enabling continuous driving with excellent responsiveness, the output of the artificial muscle actuator can be changed.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0007] FIG. 1 is a conceptual diagram showing an embodiment of the artificial muscle actuator device 100. In FIG. 1, the dashed line indicates the artificial muscle actuator 1 in the state before activation, and the solid line indicates the artificial muscle actuator 1 in the state after activation. In the present embodiment, the direction along the central axis O of the elastic cylinder portion 3 is referred to as the axial direction, the direction along a straight line orthogonal to the central axis O is referred to as the radial direction, and the direction around the central axis O is referred to as the circumferential direction.

[0008] As shown in FIG. 1, the artificial muscle actuator device 100 according to the present embodiment includes an artificial muscle actuator 1, a mixture supply device 20, and an ignition control device 40. As shown in FIG. 1, the artificial muscle actuator 1 according to the embodiment includes an elastic cylinder portion 3 that forms a combustion chamber 2, an ignition device 4 that ignites a mixture of fuel and air in the combustion chamber 2, and a restraint member 5 that restrains the elastic cylinder portion 3 so as to deform in the axial direction by the expansion of the combustion gas in the combustion chamber 2.

[0009] The elastic cylinder portion 3 may have a cylindrical shape centered on the central axis O, or may have a cylindrical shape other than the cylindrical shape (for example, an elliptical cylindrical shape, a rectangular cylindrical shape, etc.). The inner peripheral surface of the elastic cylinder portion 3 forms the combustion chamber 2. The elastic cylinder portion 3 is made of rubber or an elastomer.

[0010] In the present embodiment, the artificial muscle actuator 1 has two lid members 6 that are respectively fixed to both axial ends 3a of the elastic cylinder portion 3. One lid member 6 is fixed to one end 3a of the elastic cylinder portion 3, and the other lid member 6 is fixed to the other end 3a of the elastic cylinder portion 3 by fixing means (not shown). Therefore, the radial deformation of both ends 3a of the elastic cylinder portion 3 is restricted by the fixing of the lid members 6. Each lid member 6 forms the combustion chamber 2.

[0011] In addition, when the inner peripheral surface of the elastic cylinder portion 3 described above forms the combustion chamber 2, or when each lid member 6 forms the combustion chamber 2, it means that the inner peripheral surface of the elastic cylinder portion 3 or the lid member 6; 6 directly forms the space of the combustion chamber 2, or indirectly forms it so as to surround the space of the combustion chamber 2 formed of other materials.

[0012] In the present embodiment, an ignition device 4 is provided on one of the lid members 6. The ignition device 4 can be configured by, for example, a spark plug. The ignition device 4 is provided in the combustion chamber 2. The ignition device 4 is electrically connected to, for example, an ignition control device 40.

[0013] The ignition control device 40 controls the generation of sparks of the ignition device 4. The ignition control device 40 can be configured by using, for example, a computer, and can control the sparks generated by the ignition device 4 by outputting a signal to the ignition device 4 based on a program. The control of the ignition device 4 by the ignition control device 40 may generate sparks at a constant ignition frequency or make the ignition frequency variable in the middle, and can be set as appropriate.

[0014] Further, the artificial muscle actuator 1 is configured to have two ventilation ports 10; 12 that communicate the inside of the combustion chamber 2 and the external space, which is the space outside the artificial muscle actuator 1. In the present embodiment, as shown in FIG. 1, the ventilation ports 10; 12 are provided on each of one lid member 6 and the other lid member 6. The ventilation port 10 of the lid member 6 having the ignition device 4 is used for supplying the air-fuel mixture (hereinafter referred to as the air supply ventilation port 10), and the ventilation port 12 of the other lid member 6 is provided for exhausting the combustion gas (hereinafter referred to as the exhaust ventilation port 12).

[0015] An air-fuel mixture supply device 20 for supplying the air-fuel mixture to the combustion chamber 2 is connected to the air supply ventilation port 10. The air-fuel mixture supply device 20 is configured to be able to supply, for example, an air-fuel mixture obtained by mixing fuel and air to the combustion chamber 2 through the air supply ventilation port 10.

[0016] Note that the configuration for making the combustion chamber 2 contain an air-fuel mixture is not particularly limited. The air-fuel mixture supply device 20 may be configured to introduce the air-fuel mixture into the combustion chamber 2, or may be configured to separately introduce fuel and air into the combustion chamber 2. When configured to separately introduce fuel and air into the combustion chamber 2, the fuel may be introduced in a liquid state or in a gaseous state.

[0017] The saturated vapor pressure of the fuel is preferably 1 MPa or less. According to such a configuration, it is easy to suppress the size and weight of the container for storing the fuel.

[0018] Also, the fuel preferably contains dimethyl ether. According to such a configuration, excellent environmental compatibility can be ensured. Also, the saturated vapor pressure of dimethyl ether is 0.62 MPa, which can also satisfy the above condition of 1 MPa or less.

[0019] In this embodiment, the air supply vent 10 has been described as having one, but it may be one or more. Also, although the air supply vent 10 has been described as being provided in the lid member 6 provided with the ignition device 4, it is not limited thereto. The air supply vent 10 may be provided, for example, in the elastic cylinder portion 3 or in the other lid member 6. Also, when providing one or more air supply vents 10, it is not limited to providing all of them in the same member. For example, they may be provided dispersedly in the elastic cylinder portion 3 or the two lid members 6.

[0020] The exhaust vent 12 is configured such that the inside of the combustion chamber 2 is always in communication with the external space. In this embodiment, the exhaust vent 12 has been described as having one, but it may be one or more. Also, although the exhaust vent 12 has been described as being provided in the other lid member 6 where the ignition device 4 is not provided, it is not limited thereto. The exhaust vent 12 may be provided, for example, in the elastic cylinder portion 3 or in the lid member 6 provided with the ignition device 4. When providing one or more exhaust vents 12, it is not limited to providing all of them on the same member. For example, they may be provided dispersedly on the elastic cylinder part 3 or the two lid members 6.

[0021] Also, the one or more exhaust vents 12 are not limited to a configuration that constantly communicates the combustion chamber 2 with the external space, and may be configured to open when the pressure in the combustion chamber 2 becomes a predetermined value or more to communicate the combustion chamber 2 with the external space. According to such a configuration, after operating the artificial muscle actuator 1 with combustion gas, the combustion gas can be passively discharged to the external space through one or more vents by its pressure, so that a configuration and control for actively discharging the combustion gas from the combustion chamber 2 can be made unnecessary.

[0022] The restraint member 5 restrains the elastic cylinder part 3 so that the elastic cylinder part 3 contracts and deforms in the axial direction due to the expansion of the combustion gas in the combustion chamber 2. For example, the restraint member 5 can utilize a braided cylinder body formed in a cylindrical shape by braiding fibers. The restraint member 5 is provided radially outward so as to cover the entire outer peripheral surface of the elastic cylinder part 3. That is, the artificial muscle actuator 1 according to the present embodiment is configured as a so-called McKibben type.

[0023] According to such a configuration, due to the restraint of the restraint member 5, as the intermediate part in the axial direction of the elastic cylinder part 3 expands and deforms radially outward (refer to the white arrow in FIG. 1), the elastic cylinder part 3 can be contracted and deformed in the axial direction (refer to the thick arrow in FIG. 1).

[0024] Note that the artificial muscle actuator 1 is not limited to the McKibben type, and may be, for example, an axially fiber-reinforced type. That is, the artificial muscle actuator 1 may be one in which a plurality of fibers extend in the axial direction and are arranged in the circumferential direction and embedded in the elastic cylinder part 3.

[0025] Even with such a configuration, due to the restraint of the restraint member 5, as the axial middle portion of the elastic cylinder portion 3 expands and deforms radially outward, the elastic cylinder portion 3 can be axially contracted and deformed. That is, the restraint member 5 can restrain the elastic cylinder portion 3 so that it axially contracts and deforms due to the expansion of the combustion gas in the combustion chamber 2.

[0026] According to the artificial muscle actuator 1 according to this embodiment, since the elastic cylinder portion 3 can be axially deformed (contracted) by the expansion of the combustion gas to operate the artificial muscle actuator 1, excellent responsiveness can be obtained.

[0027] Thereby, that is, it is possible to shorten the time from the input for starting operation (ignition by the ignition device 4) to the start of operation. Further, since the exhaust vent 12 of the artificial muscle actuator 1 is always open to the external space, the expanded combustion gas can be immediately discharged to the external space.

[0028] Also, when continuously operating the artificial muscle actuator 1, the air-fuel mixture may be continuously supplied from the air-fuel mixture supply device 20 to the combustion chamber 2. Then, while the supply of the air-fuel mixture from the air-fuel mixture supply device 20 to the combustion chamber 2 is continued, the ignition control device 40 outputs an ignition signal to the ignition device 4 at a predetermined cycle, whereby the artificial muscle actuator 1 can be continuously expanded and contracted.

[0029] Furthermore, according to the artificial muscle actuator device 100 according to this embodiment, a plurality of artificial muscle actuators 1 can be operated with a simple configuration.

Example

[0030] An experiment was conducted to fabricate the artificial muscle actuator device shown in Fig. 1 and continuously drive it. In the experiment, the air supply side of the artificial muscle actuator was fixed, the exhaust side was left free, and the air-fuel mixture was continuously flowed without blocking the exhaust vent 12. The air-fuel mixture used dimethyl ether as the fuel, and an air-fuel mixture with a predetermined air-fuel ratio was allowed to flow into the combustion chamber. The flow rate of the air-fuel mixture at this time was set to 13.0 L / min. Also, as experimental conditions, the ignition frequencies were set to 1, 5, and 10 Hz. The results of the experiment are shown in Fig. 2. As shown in Fig. 2, it was confirmed that the artificial muscle actuator can be continuously driven and the driving frequency can be varied according to the ignition frequency.

[0031] As shown in Fig. 3, when driving a plurality of artificial muscle actuators 1, a supply path for individually supplying fuel from the air-fuel mixture supply device 20 to each artificial muscle actuator 1 may be provided, and the ignition control device 40 and the ignition device 4 provided in each artificial muscle actuator 1 may be electrically connected individually.

[0032] At this time, the air-fuel mixture supply device 20 can be used as it is when driving one artificial muscle actuator 1. Also, the ignition control device 40 may be configured to be able to output ignition signals independently to the individually connected ignition devices 4.

[0033] For example, when driving a plurality of conventional artificial muscle actuators 1 that use compressed air, a valve for supplying compressed air to each artificial muscle actuator and a valve for discharging the compressed air supplied to the artificial muscle actuator are required. On the other hand, as in the present invention, by constantly communicating the combustion chamber 2 with the external space, while constantly supplying the air-fuel mixture to all of the plurality of artificial muscle actuators 1, only the ignition of each ignition device 4 needs to be controlled, so that the artificial muscle actuator device can have a simple configuration.

[0034] As described above, while maintaining the state in which the artificial muscle actuator device 100 is configured and the air-fuel mixture is continuously supplied from the air-fuel mixture supply device to the combustion chamber 2, the ignition control device controls ignition at a constant cycle, thereby improving the responsiveness of expansion and contraction and continuously operating the artificial muscle actuator 1 according to the ignition timing.

Explanation of Signs

[0035] 1 Artificial muscle actuator, 2 Combustion chamber, 3 Elastic cylinder part, 3a End part, 4 Ignition device, 5 Restraining member, 6 Lid member, 10 (For air supply) Vent hole, 12 (For exhaust) Vent hole, 20 Air-fuel mixture supply device, 40 Ignition control device, 100 Artificial muscle actuator device, O Central axis.

Claims

1. An elastic cylindrical portion forming a combustion chamber, a lid member closing both ends of the elastic cylindrical portion and forming a combustion chamber together with the elastic cylindrical portion, The elastic cylindrical portion facing the combustion chamber and the elastic cylindrical portion closing both ends of the elastic cylindrical portion, An ignition device for igniting an air-fuel mixture in the combustion chamber, A restraint member for restraining the elastic cylindrical portion so that the elastic cylindrical portion is deformed in the axial direction by the expansion of combustion gas in the combustion chamber, An artificial muscle actuator having a vent hole for constantly communicating the combustion chamber with the external space, An air-fuel mixture supply device for supplying an air-fuel mixture to the combustion chamber, An ignition control device for controlling ignition of the ignition device, The ignition control device is an artificial muscle actuator device that ignites in a state where an air-fuel mixture is being supplied from the air-fuel mixture supply device into the combustion chamber.

2. A plurality of the artificial muscle actuators are provided, The air-fuel mixture supply device is capable of supplying an air-fuel mixture to the plurality of artificial muscle actuators, The artificial muscle actuator device according to claim 1, wherein the ignition control device is capable of selectively igniting the ignition devices of the plurality of artificial muscle actuators.

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