JPS61157806A - Pneumatic actuator - Google Patents

Abstract

PURPOSE:To easily detect output diaplacement of an actuator by disposing output detection rods extended from both end closing elements in the interior of a pneumatic actuator, and providing electrical or optical means for detecting relative displacement of both detection rods on the respective detection rods. CONSTITUTION:Output detection members are extended from both end closing members 3 in the interior of a pneumatic actuator. One output detection member comprises an inserting member 14 supported by a support member comprises an inserting member 14 supported by a support member 12, and light transmitting portions and light intercepting portions are periodically arranged on the inserting member 14. On the other hand, the other output detection member comprises an accomodating portion 16. The inserting member 14 is inserted in the accomodating portion 16, and a light emitting element 18 and a photo detecting element 22 are fixed to both sides of the inserting member 14, with the inserting member sandwiched therebetween. In this arrangement, the output displacement of the actuator can be detected by connecting the count number of light passing through the inserting member.

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a pneumatic actuator that expands and deforms in diameter by introducing pressurized fluid and generates a contraction force in the axial direction, specifically, a pneumatic actuator when contracting. The present invention relates to a pneumatic actuator capable of detecting relative displacement between closing members at both ends of the actuator.

(Prior Art and Between @) Air bag type pneumatic actuators, which expand radially and contract longitudinally by introducing pressurized fluid, are extremely efficient compared to devices using electric motors or hydraulic cylinders. It has many excellent features not found in conventional actuators, such as being light in weight, smooth in motion, and easy to control. As such an actuator, for example, one shown in FIG. 5 is known from Japanese Patent Publication No. 5G-40878. In FIG. 5, 1 is a tubular body, 2 is a braided reinforcement structure on its outer periphery, 8 is a closing member at both ends, and 4 is a caulked cap.

For the tubular body 1, rubber or a rubber-like elastic material is useful in terms of air impermeability and flexibility, but equivalent materials such as various plastic materials may be used instead.

The braided reinforcing structure 2 has a braided structure that reaches a so-called rest angle (54°44') when the tubular body 1 expands to its maximum diameter due to internal pressure light, and is made of organic or inorganic high-tensile fibers, such as organic or inorganic high-tensile fibers. Aromatic polyamide ffl! 1 (Kevlar: trade name), twisted or untwisted filament such as ultra-fine metal wire, etc. are suitable.

One of the closing members 8 is bored on at least one side with a connecting hole 8 which communicates with the internal cavity 7 of the tubular body l via a hole 6 formed in the lengthwise direction of the nipple 5, in which a fitting 9 is mounted. Although not shown in the fitting 9, there is an operating pressure source,
For example, by connecting an air compressor by a conduit containing a flow control valve and applying a controlled pressure within the internal cavity 7 of the snow-like body 1, the braid angle of the braided reinforcing structure 2 is enlarged, i.e. by a pantograph movement, the tubular body 1 and the resulting contraction in the axial direction, ie, the distance between the connecting via holes of the closure member 8 is reduced.

However, in such a pneumatic actuator that adjusts the pressure of the applied pressurized fluid to generate displacement in the axial direction, the tubular body or braided reinforcement structure of rubber or rubber-like elastic material has a large diameter and a braided reinforcement structure. Since a so-called hysteresis error occurs, there is a problem in that the contraction length in the axial direction differs when the pressurized fluid is introduced into the internal cavity of the tubular body and when it is discharged. Therefore, in order to accurately know the degree of contraction, the pressure of the pressurized fluid must be adjusted in consideration of the hysteresis characteristics of the tubular body and the assembled structure, which makes workability difficult.

(Object of the Invention) An object of the present invention is to provide a pneumatic actuator that solves the above-mentioned problems without impairing the excellent features of the airbag type pneumatic actuator.

(Structure of the Invention) In order to achieve this object, the pneumatic actuator of the present invention has an outer periphery reinforced with a braided reinforcement structure using organic or inorganic high tensile strength fibers as a tensile reinforcement element, and has openings at both ends at least on one side. A tubular body of rubber or rubber-like elastic material sealingly joined with a closure member having a connecting hole, an insertion member provided in one closure member and extending into the internal cavity of the tubular body, and an insertion member provided in the other closure member. An accommodating portion that is provided and has a detection means for accommodating the insertion member so as to be inserted therethrough and detecting displacement of the insertion member, and an output means for outputting a relative displacement between the two closing members based on a detection signal from the detection means. It's getting better.

(Operation of the Invention) Therefore, in the pneumatic actuator of the present invention having the above-described structure, when pressurized fluid is supplied into the internal cavity of the tubular body, the actuator expands in diameter and contracts in the axial direction. The closing members sealing the end openings of the tubular body are therefore close to each other. For this reason, the insertion member attached to one closure member will penetrate further into the receptacle attached to the other closure member. By the way, the accommodating portion is provided with a detection means for detecting the amount of penetration of the insertion member, that is, the amount of relative displacement between both open chain members, and outputs a detection signal proportional to the amount of relative displacement. This output signal is guided to an output means to output the amount of relative displacement between both closing members. Therefore, it is no longer necessary to take into account hysteresis errors of the tubular body and the braided reinforcement structure, which are problematic due to the supply and discharge of pressurized fluid to and from the tubular body.

(Example) The present invention will be described in detail below with reference to the drawings. For the sake of brevity, the same reference numerals are used to denote the same functions as those in the IE5 diagram.

FIG. 1(a) is a partial cross-sectional view of the pneumatic actuator of the present invention, in which a tubular body 1 made of rubber or rubber-like elastic material is reinforced by a braided reinforcement structure 2 of high-tensile fibers. The outer periphery is reinforced, and the openings at both ends are closed by a closing member 8.
The sealing and bonding is carried out as before. Furthermore, the tubular body 1 and the braided reinforcing structure 2 are more securely joined to the nipple 5 of the closure member 3 by means of a cooperating swage cap 4. A fitting 9 is attached to a connecting hole 8 provided in the closing member 3 in the internal cavity 7 of the tubular body 1 to supply and discharge pressurized fluid.

A support member 1z is fixed to the inner cavity side end surface of one of the closing members 3, in this embodiment, the closing member 8 on the side of the fitting 9, using a conventionally known method such as screwing or gluing. An insertion member 14 is attached to this support member 12 using a known method such as screwing or gluing. As shown in FIG. An accommodating part 16 for accommodating the insertion member 14 so as to be freely inserted therein is fixed to the other closing member 3 that is spaced apart from the member 3.The accommodating part 16 has a mechanism for detecting displacement of the insertion member 14 in the axial direction. The detection means, as shown in fbl in FIG. It includes a detection element 20 facing the insertion member 14 and a light receiving element 20 that receives light from the light source 18a that has passed through the insertion member 14 and the detection element 20. In addition, the housing section 16
has a guide 24 which ensures that the insertion member 14 moves relative to the detection means in a substantially constant geometrical relationship at all times.

Pressurized fluid is introduced into the internal cavity 7 of the pneumatic actuator thus configured through the fitting 9. As a result the actuator, i.e. the tubular body 1
has an expanded diameter of f, the relative distance between the self-closing members 8 is reduced, and the insertion member 14 enters into the accommodation portion. At this time, the light receiving element 22 detects a change in the amount of ye according to the position of each slit of the insertion member and the detection element. The state of change in this detection signal is shown in FIG. 1(c). The detection signal from the light receiving element 22 is sent to the output means 2 via the lead wire 26.
8 will be communicated. The output means 28 counts the number of pitches corresponding to the pitch of the slits of the insertion member, and calculates and counts the value between the maximum 'e 'i LMAX and the minimum light amount LMiN by interpolation. Output and display the relative displacement between the closing members. Note that the output means 28
It is desirable that the actuator has a reset function that sets the display to zero when a constant pressure fluid is applied to the actuator and the actuator is set.

Contrary to the above case, when the pressurized fluid is discharged from inside the internal cavity 7, both open chain members move in a direction away from each other, so that the insertion member is moved relative to the detection means at fal in FIG. Move to the left -1. On the other hand, the output means 28 performs the reduction based on the signal from the detection means and outputs and displays the result, so that the relative displacement between the two closing members can always be accurately known.

Note that the pitch of the slits of the insertion member and the detection element is selected in relation to the displacement accuracy required of the actuator.

FIG. 2 shows another embodiment of the invention. Note that this embodiment differs only in the configurations of the detection section and the housing section 16 from the embodiment shown in FIG. 1, and for the sake of brevity, description of other parts will be omitted.

In this embodiment, the insertion member 14 attached to the support member 12 is made of a magnetic material such as iron. on the other hand,
A coil 32 serving as a detection means is provided inside the accommodating portion 16 that slidably supports the support member 12 by the support wall 80 so as to face the insertion member 14 and be spaced apart therefrom. Note that the support wall 8
0 functions as a guide for the support member 12 similarly to the guide z4 in the first embodiment. The coil 82 is shown in Figure II2 (
As shown in b), the primary coil P and the secondary coil S, S,
Together with the insertion member 14, it constitutes a so-called differential variable pressure converter, and in response to the displacement of the insertion member 14, (cl.
It outputs detection signals as shown by straight lines ab and bc as shown in FIG. In (cl) of FIG. 2, a region where the displacement and the induced electromotive force are proportional, that is, a linear range (LR) is used.In the differential transformer, the point where the insertion member 14 is located at the center of the coil 82 is the boundary. and the phase is 180°
Therefore, the output means of the pneumatic actuator of this embodiment has an inverter that inverts the polarity of the output signal between the holes, and the point a′ is apparently the bow power “
By applying a bias voltage so that the voltage becomes zero, it is possible to output and display the detection signal in the same manner as in the embodiment shown in FIG.

FIG. 8 shows yet another embodiment. In this example, a coil 32 is used as a detection means as in the embodiment shown in FIG. In order to prevent the hydraulic oil 34 from flowing into the internal cavity 7 of the tubular body 7, the support wall 80 is provided with a sealing means 30a to seal the support member 12 and the support wall. With this configuration, an oriice is formed between the coil B2 and the insertion member 14, and the detection means functions as a damper.
Vibrations caused by the compressibility of the air and the elasticity of the actuator, which could be a problem in the two '44 examples described above, are absorbed, allowing for smoother operation.

Note that the opening area of the oriice is determined based on the dimensions, material, and applied pressure of the actuator, but in that case, a spacer may be provided between the coil 82 and the wall surface of the housing section 16. Alternatively, the diameter of the insertion member 14 may be changed as appropriate.

Therefore, such a pneumatic actuator uses a set of at least two actuators, each of which has one end connected to a fixed part and the other end connected directly or indirectly to a driven member, and pressurized fluid is supplied to each actuator. It is suitable for a device that imparts movement to a driven member by supplying and discharging.

An example of such a drive device is shown in FIG. 10 in the diagram
a.

10b each represents a pneumatic actuator according to the present invention, and 9a and 9b each represent a fitting of each actuator. Reference numeral 86 indicates a fixed portion, 88 indicates a wire 88 as a connecting member, and a boo U 42 as a driven member is pivotally supported on a support column 40 fixed to the fixed portion 86.
Wind K.

The pulley 42 is rotated as shown by arrow A by supplying pressurized fluid at a predetermined pressure and discharging the pressurized fluid to each actuator of the drive device that has been set in advance to the operating state. . At this time, the amount of contraction and expansion of each actuator can be directly detected by the detection means. On the other hand, the wire 88 is elongated due to a tensile load based on the difference in the contraction force of both actuators, and if the magnitude of this elongation is known, the rotation angle of the pulley can be determined more accurately.

By the way, it is known that the contractile force F of the actuator when a pressurized fluid having a current pressure P acts on the pneumatic actuator is given by the following equation.

D: Diameter of the elastic contractile body θo: Braid angle ε of the li braided reinforcement structure: Contraction rate Since the pressure P and the contraction rate ε are now known, the wire 88
The tensile load acting on can be calculated immediately.

Therefore, by adding a function to the output means to compensate for the elongation occurring in the wire 88 based on the contraction rate obtained by processing the pressure acting on each actuator and the detection signal from the detection means, the movement of the driven member can be more accurately determined. You can know.

Alternatively, the output means may be configured to directly detect the force acting on the wire 38 and display the elongation of the wire.

It should be noted that the present invention is not limited to these embodiments, and can be modified in various ways. The servo system has excellent responsiveness and a comparison circuit that compares the detection signal and input signal of the input signal and sends a control signal to the control means so that the difference between the input signal and output signal is within an allowable range. You can also.

(Effects of the Invention) As detailed above, in the pneumatic actuator of the present invention, the detection detects the relative displacement between the two closing members that seal and join the openings at both ends of the tubular body into the internal cavity of the tubular body. By arranging the means, the axial length of the actuator can be accurately known without considering the hysteresis characteristics in the tubular body or the braided reinforcement structure of rubber or rubber-like elastic material, making the actuator easy to position. be able to. Furthermore, since a damper function can be added, there is no need to consider various problems caused by the compressibility of air, making it suitable as an actuator for use in precision equipment assembly work. Furthermore, since the detection means is disposed within the internal cavity, less compressed air is required to drive the actuator, which has the advantage of reducing running costs.

[Brief explanation of the drawing]

fal in figure m1 is a partially sectional front view showing one embodiment of the pneumatic actuator of the present invention, and fbl in FIG. Figure 1 (cl is the first
A schematic M diagram showing the output of the detection means shown at fbl in the figure; FIG. 2(a) is a partially sectional front view showing another embodiment of the pneumatic actuator of the invention; (bl and let are diagrams showing the configuration of the detection means and its output shown in (al) of FIG. 2, FIG. 3 is a partial cross-sectional view of another embodiment of the pneumatic actuator of the present invention, 1@45 is a route diagram showing a drive device using the pneumatic actuator of the present invention, and Figure 5 is a partially sectional front view showing a conventional pneumatic actuator. 1... Tubular Body 2... Braided reinforcement structure 3
... Closing member 4 ... Caulking cap 5.
... Nipple 6 ... Hole 7 ... Internal cavity
8... Connection hole 9... Fitting 10... Pneumatic actuator 12...
Support member 14... Insertion member 16... Accommodation part 18... Output''/l, element 18a...
Light source 18b...Condensing lens 20...Detection element 22...Receiver ytJ element 24...Guide 26...Lead wire 28...Output means 30...Support wall 80a...Sealing means 8
2... Coil 84... Hydraulic oil 86...
Fixed part 88...Wire 40...Support column 42...Pulley

Claims (1)

[Claims] 1. Rubber or rubber whose outer periphery is reinforced with a braided reinforcing structure using organic or inorganic high tensile strength fibers as tensile reinforcement elements, and whose openings at both ends are sealed and bonded with a closing member having a connection hole on at least one side. A tubular body made of a shaped elastic material, an insertion member provided on one closing member and extending into the internal cavity of the tubular body, and an insertion member provided on the other closure member that accommodates the insertion member so as to be freely inserted and allows displacement of the insertion member. and an output means that outputs the relative displacement between both closing members based on the detection signal from the detection means, and expands and deforms in diameter in the axial direction by supplying and discharging pressurized fluid. A pneumatic actuator characterized by generating contraction force.