JPH0754122B2 - Pneumatic actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a pneumatic actuator that expands and deforms by the introduction of a pressurized fluid to generate a contracting force in the axial direction,
In particular, the present invention relates to a pneumatic actuator having a compact and simple structure for detecting a pressure in an inner cavity of a tubular body and having a built-in pressure detecting means.

(Prior art and its problems) A pneumatic actuator, which expands in the radial direction and contracts in the longitudinal direction by introducing a pressurized fluid, is lighter in weight and moves less than a device using an electric motor or a hydraulic cylinder. It has many excellent features that conventional actuators do not have, such as smooth and reliable positioning. As such an actuator, for example, the one shown in FIG. 4 is known from Japanese Patent Publication No. 52-40378. In the figure, 1 is a tubular body, 2 is a braided reinforcing structure on the outer periphery thereof, 3 is a closing member at both ends, and 4 is a caulking cap.

For the tubular body 1, rubber or a rubber-like elastic material is useful in terms of air impermeability and flexibility, but a uniform material, for example, various plastic materials may be substituted.

The braided reinforcing structure 2 has a braided structure that reaches a so-called static angle (54 ° 44 ′) when the tubular body 1 is filled with the internal pressure and has a maximum expansion diameter. Group polyamide fibers (Kevlar: trade name) and twisted or untwisted bundles of filaments such as ultrafine metal wires are suitable.

At least one side of the closing member 3 has a connection hole 8 communicating with the internal cavity 7 of the tubular body 1 through a hole 6 formed in the lengthwise direction of the nipple 5, and a fitting 9 is attached thereto. Although not shown, an operating pressure source, for example, an air compressor, is connected to the fitting 9 by a pipe line including a flow control valve, and a control pressure is applied to the inside cavity 7 of the tubular body 1 so that the braided reinforcing structure 2 can be manufactured. Expansion of the braid angle, that is, expansion of the tubular body 1 due to pantograph movement, and contraction in the axial direction resulting therefrom, that is, closure member 3.
This results in a reduction in the distance between the connecting pin holes 10.

However, in such a conventional pneumatic actuator, since the pressure detecting means for detecting the pressure inside the actuator is provided in the conduit between the operating pressure source and the actuator, the pressure detecting means and the conduit are not connected to each other. In addition to the problem of leakage of the pressurized fluid between the two, there is a problem that the installation location is limited by the volume occupied by the pressure detecting means itself.

Further, since the pressure inside the internal cavity of the actuator cannot be directly detected, it is not possible to accurately know the pressure of the pressurized fluid that contributes to the diametrical deformation of the actuator due to the influence of conduit loss and other losses. It was

(Object of the Invention) The present invention solves all such problems of the prior art without impairing the advantages of the pneumatic actuator. The present invention provides a pneumatic actuator capable of always accurately measuring the internal cavity pressure without any restriction.

(Structure and Operation of the Invention) In order to achieve this object, in the pneumatic actuator of the present invention, a tubular body made of rubber or a rubber-like elastic material having a braided structure of organic or inorganic high-strength fibers reinforced on the outer periphery is used. Both end openings are sealed and joined by respective closing members, and one of the closing members is provided with a pressure detecting means for detecting the magnitude of the positive pressure of the internal cavity of the tubular body, and the other closing member. In which a connection hole communicating with the inner cavity of the tubular body is provided, and when the pressurized fluid is introduced through the connection hole to cause diametrical expansion and contraction force in the axial direction, the one closing member is tubular. It comprises a nipple inserted into the body and a closing member main body screwed to the rear end portion of the nipple, and the pressure detecting means includes an axial through hole provided in the nipple and a closing member side thereof. axis It is composed of a support body that closes the linear through hole, a pressure sensor attached to the support body, and an atmosphere opening passage that is formed in the closure member body and introduces atmospheric pressure to the back surface of the support body.

Further, in another pneumatic actuator of the present invention, in particular, the one closing member is composed of a nipple to be inserted into the tubular body and an external protruding portion integrated with the nipple, and the pressure detecting means is provided. , A through hole that extends in the axial direction of the nipple and opens to the internal cavity and that opens to the atmosphere at the external protruding portion, a support that closes the opening of the nipple to the internal cavity, and is attached to this support It is composed of a pressure sensor.

As described above, in the pneumatic actuator of the present invention, since the pressure detecting means is built in the one closing member, the internal cavity internal pressure of the tubular body can be directly measured with high accuracy. A separate and independent pressure detecting means for measurement is not required, and the degree of freedom in arranging the actuator can be greatly increased.

Further, since the pressure detecting means here can be configured by a hole that opens to the internal cavity of the tubular body and opens to the atmosphere, a support that closes the hole, and a pressure sensor attached to the support, The possibility of leakage of pressurized fluid has been sufficiently removed, and the structure has been made extremely simple.
It can be sufficiently lightweight and small.
Therefore, the cost of the entire actuator including the pressure detecting means can be reduced, the actuator can be operated with little influence of the weight of the pressure detecting means, and the outer contour dimension of the closing member can be reduced. It can be similar to that of technology.

In addition, according to this pneumatic actuator, since the pressure inside the internal cavity can be directly measured by the pressure detecting means, the pressure in the internal cavity can be directly measured. The leak of the pressurized fluid can be detected easily and quickly.

(Example) Hereinafter, the pneumatic actuator of the present invention will be described in detail with reference to the drawings. For the sake of simplification, the components denoted by the same reference numerals as those in FIG. 3 have the same or equivalent functions.

FIG. 1 shows a preferred embodiment of the present invention. 1 is a tubular body, 2
Is a braided reinforcing structure on the outer periphery thereof, 3a is a closing member on the pressurized fluid introduction side for sealing and adhering one end of the tubular body 1, and 3b is a closing member for sealing and adhering the other end of the tubular body 1. Attaching the tubular body 1 and the braided reinforcing structure 2 to the respective closing members 3a, 3b,
Further, the caulking cap 4 is used to fix airtightly. The materials of the tubular body, the braided reinforcing structure and the like are the same as those conventionally known.

The inlet side closing member 3a for the pressurized fluid is fitted with the pressurized fluid supplied from an operation pressure source (not shown) to the fitting 9 and the communication hole 6.
Through the inner cavity 7 of the tubular body 1.

The closing member 3b which faces the closing member 3a and seals and joins the other end of the tubular body 1 is described in detail in FIG. The closure member 3b comprises a nipple 5 and a closure member body 33 screwed onto the nipple. The nipple 5 has a recess 15 that communicates with the internal cavity 7 through a communication hole 6a at the end of the tubular body 1 that is separated from the internal cavity 7.
And the spacer 16 is disposed in this recess. On the other hand, the closing member main body 33 is provided with a back pressure chamber 20 having a pressure sensor accommodating concave portion 21 at the end facing the concave portion 15 of the nipple 5, which is separated from the connecting pin hole 10 (see FIG. 1). Pressure chamber has a hole 22
Through the atmosphere.

Here, the pressure detector is located adjacent to the spacer 16 and cooperates with the spacer 16 to close the through hole of the nipple 5, and the support 17 is fixed to the support 17 by, for example, sticking. Piezoelectric ceramic element 18 and piezoelectric ceramic element 18
And a connecting wire 19 for taking out a detection signal generated in the internal cavity 7 together with the spacer 16 in an airtight manner.

Therefore, when a pressurized fluid is introduced into the pneumatic actuator constructed as described above, the pressure difference between the back pressure chamber 20 communicating with the atmosphere through the hole 22 and the inside cavity 7 of the tubular body 1 is reduced. 18 will detect immediately.

FIG. 3 shows another embodiment. In the embodiment shown in FIGS. 1 and 2, the closing member 3b has a one-piece structure in which the closing member main body 33 and the nipple 5 are screwed together, but in this embodiment, the internal cavity 7 of the closing member 3b is formed. While closing the end surface of the nipple on the side of the support body of the piezoelectric ceramic element 18,
The end portion 5a of the nipple 5 is provided with a recess 25 that forms the back pressure chamber 20. This recess communicates with the atmosphere through the hole 22. Here, the closing of the nipple end surface 5a is performed by air-tightly fixing the thin plate 17a using, for example, an adhesive. Sheet 17a
A piezoelectric ceramic element 18 is adhered to the surface of the back pressure chamber 20 side, and a detection signal corresponding to the pressure difference between the back pressure chamber 20 and the internal cavity 7 cannot be output via the connection line 19. Of course.

Therefore, in the pneumatic actuator of this embodiment, it is not necessary to separately form the nipple 5 and the closing member main body 33, which facilitates the processing of the closing member 3b, and
It can be cheaper than the actuator shown in the figure.

As the pressure sensor, not only the piezoelectric ceramic element as in the present embodiment but also a semiconductor pressure sensor, a strain gauge type pressure sensor, etc. can be used.

(Effects of the Invention) As described in detail above, in the pneumatic actuator of the present invention, one end of the tubular member made of rubber or a rubber-like elastic material is attached to one of the closing members which seals and joins the both ends of the tubular member. Since the pressure detecting means for detecting the pressure is built in, it is not necessary to separately provide the pressure detecting means in the conduit for guiding the pressurized fluid for driving to the actuator, which not only simplifies the piping but also includes the pressure detecting means. By making the entire pneumatic actuator compact, the degree of freedom in arranging the actuators can be greatly increased. Further, there is no problem of leakage of the pressurized fluid between the pressure detecting means and the pipe line, and moreover, since the pressure inside the internal cavity of the tubular body can be directly and accurately detected, the pressure control of the pressurized fluid can be performed. It has many advantages such as being more accurate and being able to easily detect leaks from the tubular body of pressurized fluid due to abnormalities of the tubular body, especially fatigue or damage.

In addition, since the pressure detecting means here has a simple structure, the cost of the entire actuator can be made low, and since it is lightweight and small, the pressure detecting means can be respectively The influence of the weight of the actuator on the operation of the actuator can be made extremely small, and the outer contour dimension of the closing member incorporating the pressure detecting means is made to be similar to that of the prior art, and the actuator including the pressure detecting means The installation space can be reduced more effectively.

[Brief description of drawings]

FIG. 1 is a front view showing a part of a pneumatic actuator according to the present invention as a cross section, and FIG. 2 is a cross sectional view showing a part of a closing member used for the pneumatic actuator shown in FIG. FIG. 3 is a sectional view showing a part of another closing member suitable for the pneumatic actuator shown in FIG. 1, and FIG. 4 is a front view showing a part of a conventional pneumatic actuator in section. is there. 1 ... Tubular body, 2 ... Braided reinforcing structure 3,3a, 3b ... Closing member, 4 ... Caulking cap 5 ... Nipple, 6,6a ... Communication hole 7 ... Internal cavity, 8 ... Connection Hole 9 ... Fitting, 10 ... Connection pin hole 15,25 ... Recess, 16 ... Spacer 17 ... Support, 17a ... Thin plate 18 ... Piezoceramic element, 19 ... Connection wire 20 ... Back pressure Chamber, 21 ... Pressure sensor housing recess 22 ... Hole, 33 ... Closing member body

Claims (2)

[Claims] 1. A tubular body made of rubber or a rubber-like elastic material whose outer periphery is reinforced with a braided structure of organic or inorganic high-tensile fibers, is sealed and joined at its both end openings with respective closing members,
The pressure detecting means for detecting the pressure of the internal cavity of the tubular body is provided in either one of the closing members, and the other closing member is provided with a connection hole communicating with the internal cavity of the tubular body, and the connection hole is passed through the connection hole. A pneumatic actuator that expands radially by introducing a pressurized fluid to generate a contracting force in an axial direction, wherein the one closing member is provided at a nipple to be inserted into a tubular body and at a rear end portion of the nipple. A closing member body screwed to the pressure detecting means, an axial through hole provided in the nipple, a support body for closing the through hole on the closing member side, and a pressure sensor attached to the support body. A pneumatic actuator formed on the main body of the closing member and having an atmosphere opening passage for introducing atmospheric pressure to the back surface of the support. 2. A tubular body made of rubber or a rubber-like elastic material whose outer periphery is reinforced with a braided structure of organic or inorganic high-strength fibers, is sealed and joined at its both ends with respective closing members.
The pressure detecting means for detecting the pressure of the internal cavity of the tubular body is provided in either one of the closing members, and the other closing member is provided with a connection hole communicating with the internal cavity of the tubular body, and the connection hole is passed through the connection hole. A pneumatic actuator that expands and expands by the introduction of a pressurized fluid to generate a contracting force in the axial direction, wherein the one closing member is a nipple that is inserted into the tubular body, and an external body that is integral with the nipple. The pressure detecting means is formed of a projecting portion and extends in the axial direction of the nipple to open to the internal cavity, and a through hole opening to the atmosphere at the external projecting portion and an opening of the nipple to the internal cavity. A pneumatic actuator composed of a support that closes and a pressure sensor attached to the support.