JP2002125357A - Power supply apparatus and system employing the apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply apparatus which consumes little air, has high reliability, and has high conversion efficiency, and to provide a system employing the apparatus. SOLUTION: This power supply apparatus comprises a pneumatic actuator unit 11, composed of a cylinder 13 and a piston 14 and a power generating unit 12, which converts the linear motion of the piston 14 into a relative motion between a coil 38 and a magnetic circuit 44. The coil 38 is attached to the tip of the piston 14 via a bobbin 41 and the magnetic circuit 44 comprises a yoke 37, a pole piece 39 and a magnet 40. The piston 14 is moved straight reciprocated in a straight line by supplying of compressed air.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device, and more particularly, to a power supply device suitable for various instruments and controllers installed at a site of a petrochemical plant or the like and a system using the same.

[0002]

2. Description of the Related Art Generally, in a petrochemical plant or the like, in order to prevent the possibility of ignition of combustible gas or the like,
An electric instrument meeting explosion-proof standards or a pneumatic instrument having no electric circuit part is used.

[0003] In recent years, low-cost, high-precision, high-performance electric instruments are remarkably popularized compared with pneumatic instruments, but pneumatic instruments are still often used. The reason is,
Electric meters require the cost of laying power cables for their introduction, which makes it very troublesome to handle during maintenance and change the installation location, whereas pneumatic meters require valves to drive valves. Compressed air piping is always nearby, and in the case of replacement, the air source for instrumentation laid on the site can be used as it is, the cost for laying is small, and there is no danger of ignition due to the structure. This is because there is no need to perform maintenance work or change the installation location.

However, pneumatic instruments are inferior to electric instruments in terms of price, accuracy, and function. Therefore, a pneumatic instrument can be used without having to lay a power cable by incorporating a power supply device. There is a long-awaited need for electric instruments.

For example, JP-A-2-50299 discloses an air turbine and a generator connected to the output shaft of the air turbine. The air turbine is driven by high-pressure air and generated by the generator. An explosion-proof electronic weigher that supplies electric power to a load converter is disclosed. Japanese Patent Application Laid-Open No. 62-185531 discloses a power supply device in which a generator is driven by an air motor and power generated by the generator is supplied to a control device. As described above, all of the conventional power supply devices convert the energy of the compressed air supplied from the air source at the site into rotational force to drive the generator to generate electric power.

[0006]

Since instruments in a petrochemical plant or the like may operate continuously for several years to several tens of years once they are introduced, first, as a power supply device, first, the air consumption is reduced. Is required to be small. That is, if the air consumption is large, not only the running cost is increased, but also an additional compressor is required, which is more expensive than laying the power cable.
Second, high reliability is required. In other words, frequent maintenance not only increases the cost than laying the power cable, but also causes a plant shutdown if a failure occurs.

[0007] Considering the above-mentioned conventional power supply device from such a viewpoint, the above requirement is not satisfied for the following reasons, and the product has not yet been commercialized. That is, a rotary drive type pneumatic actuator is roughly classified into a positive displacement type (air motor) that obtains a rotational force by pressure energy,
It can be divided into a speed type (air turbine) in which the rotational force is obtained by the speed of air and pressure energy. In the power supply device disclosed in the above patent publication, the configuration of the air motor or the air turbine is not clear, but it is considered that the following configuration can be applied. As a positive displacement air motor, a vane type pneumatic motor shown in FIG. 18 is generally used. Since this pneumatic motor performs energy conversion in a state where the high-pressure side and the low-pressure side are sealed, there is an advantage that the conversion efficiency (power generation / air consumption) is high. However, in the case of the vane type pneumatic motor, the number of parts increases because it is necessary to press the vane 103 against the inner wall of the cylinder 104 using the spring 102 in order to reliably seal the expansion chamber 101 in which the volume changes. In addition, there is a problem that wear of the sliding portion between the tip of the vane and the wall of the pump chamber is inevitable, and the reliability is low. Note that the term “sealing” is used here, but actually does not necessarily achieve complete sealing, and some air leakage exists. The term "sealing" in the present specification means that the moment when the pressure is balanced through the gap is sufficiently late as compared with the driving cycle of the actuator.

In the case of an air turbine, a turbine wheel 111 is mounted on a rotating shaft 110 as shown in FIG. 19, and compressed air is blown from a nozzle 112 to a blade 113 to rotate the turbine wheel 111. There is an advantage that there is no press-contact part only in the moving part, and the number of parts and wear are small and reliability is high as compared with the vane type. However, since energy conversion is performed in a state where the high-pressure side and the low-pressure side are not sealed, there is a problem that the conversion efficiency is low and the air consumption is high (several tens NL / min) as compared with the positive displacement type.

It is an object of the present invention to provide a power supply device which consumes less air and has high reliability and high conversion efficiency, and a system using the same.

[0010]

According to a first aspect of the present invention, there is provided a power supply device comprising a cylinder and a piston, and a pneumatic actuator for linearly reciprocating the piston by supplying compressed air. And a power generating unit for converting the linear reciprocating motion of the piston into a relative reciprocating motion of a coil and a magnetic circuit to generate power.

A power supply device according to a second aspect of the present invention is the power supply device according to the first aspect.
In the invention, a hydrostatic air bearing is provided between the cylinder and the piston.

According to a third aspect of the present invention, there is provided a power supply device comprising:
In the invention, a dynamic pressure air bearing is provided between the cylinder and the piston.

[0013] The system according to a fourth aspect of the present invention is the system according to the first aspect,
A power supply device according to the second or third aspect of the invention, and a device to be supplied to which power is supplied from the power supply device.

In the first aspect, energy conversion is performed in a state where the high-pressure side and the low-pressure side are sealed, so that energy conversion efficiency is high and air consumption is small. Further, since the cylinder inner chamber, whose volume changes, is obtained by sliding contact between the cylinder and the piston, the number of parts and wear are small. In the second invention, since the static pressure air bearing is used, the piston does not directly contact the cylinder, and friction and wear hardly occur. In the third aspect, since the dynamic pressure air bearing is used, the piston does not directly contact the cylinder, and friction and wear hardly occur. In the fourth invention, the power supply device supplies power to the device to be supplied. As the device to be supplied, an electric instrument meeting explosion-proof standards or a pneumatic instrument having no electric circuit part is used.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is a sectional view showing an embodiment of a system in which the present invention is applied to a field type pressure gauge, FIG. 2 is a sectional view of the power supply device, FIG. 3 is a diagram showing a power supply circuit, and FIG. FIG. In FIG. 1, reference numeral 1 denotes a pipe for feeding a pressure fluid such as LPG, and 2 denotes a pressure gauge (supply-side device) for measuring the pressure of the pressure fluid.

The pressure gauge 2 is a conventionally well-known one, and includes a pressure-resistant explosion-proof container 3, a pressure sensor 4, an electronic control circuit 5, a liquid crystal display 6, and the like. Through the pressure sensor 4 to detect the pressure, and amplify and calculate the detection signal by the electronic control circuit 5 so that the signal is displayed on the liquid crystal display device 6.
The data is transmitted to an external control device. Further, the pressure gauge 2 includes a power supply device 8 for supplying electric power to the pressure sensor 4 and a power supply circuit 9 thereof, and these constitute a system.

In FIG. 2, the power supply unit 8 includes a pneumatic actuator unit 11 and a power generation unit 12. The pneumatic actuator section 11 includes a cylinder 13
And an oilless bearing 15 in the cylinder 13.
The piston 14 is slidably inserted through (15a to 15d) and is fixed to the outer wall of the container 3 in a state that meets explosion-proof standards as shown in FIG.

The cylinder 13 comprises a cylindrical cylinder body 13A having both ends open, a cover 13B fixed to one end face 13a of the cylinder body 13A by a plurality of bolts 16, and the power generation section 13b at the other end face 13b. Part 12
Is installed. The cylinder body 13A has a large-diameter hole 17 and a small-diameter hole 18 having different inner diameters. The large-diameter hole 17 is closed by the cover 13B, and an air supply port 19 communicating with the large-diameter hole 17 on the peripheral surface. An exhaust port 20 communicating with the hole 18 is formed. The air supply port 19 is connected to a compressed air pipe 21 (FIG. 1) via a pipe 22, and is always supplied with compressed air having a pressure Ps (for example, = 200 [KPa]). The exhaust port 20 is open to the atmosphere.

In the inner circumference of the large diameter hole 17 and the small diameter hole 18,
Two oilless bearings 15a and 15 with different lengths
b, 15c and 15d are fitted and fixed respectively. The two oil-less bearings 15a and 15b are separated from each other and incorporated into the large-diameter hole 17, so that the large-diameter hole 17 and the air supply port 19 communicate with each other through a gap 24 formed between the opposed end faces. The gap 24 is set sufficiently smaller than the hole diameter of the air supply port 19. Similarly, the two oil-less bearings 15c and 15d are separated from each other and incorporated into the small-diameter hole 18, so that the small-diameter hole 18 and the exhaust port 20 communicate with each other through a gap 25 formed between the opposed end faces. This gap 25 is
Is set to be sufficiently larger than the hole diameter. As the oilless bearing 15, an oil-impregnated sintered metal, a cylindrical bearing whose inner peripheral surface is coated with a material having a small friction coefficient such as a fluororesin, or the like is used.

The piston 14 has two large diameter holes 17 formed therein.
It comprises a piston body 14A that partitions into two chambers (expansion chambers) 27A and 27B, and a rod 14B that penetrates the small-diameter hole 18, and has a center hole 28 and two small holes 29 and 30. The center hole 28 is opened at the center of the back surface of the piston body 14A, and has a back end formed of a non-through hole extending to a middle portion in the longitudinal direction of the rod 14B. The two small holes 29 and 30 communicate with each other on the back end side. are doing. The small holes 29, 30 are radial holes orthogonal to the axis of the rod 14B, and are formed at intervals slightly shorter than the length of the oilless bearing 15c. Piston body 14A and rod 14
An annular groove 31 is formed in the connecting portion of B.

The power generation unit 12 includes the cylinder body 13
A cylindrical yoke holder 34 fixed to the other end surface 13b of A by a plurality of bolts 33;
, A cylindrical yoke 37 fitted in an opening opposite to the cylinder 13 side and fixed with a plurality of screws 36, a coil 38, a pole piece 39, a magnet 40, etc. incorporated in the yoke 37. It is composed of

The coil 38 is formed by winding a conducting wire having a total length of 1 around the distal end of the bobbin 41, and is electrically connected to the power supply circuit 9 via a cable 42. The bobbin 41 is fixed to a distal end surface of the rod 14B by a mounting screw 43.

The pole piece 39 and the magnet 40
The magnetic circuit 44 is formed together with the yoke 37, is formed in a disk shape having an outer diameter smaller than the inner diameter of the bobbin 41, is laminated, and is fixed to the inner center of the yoke 37. The inner circumference of the yoke 37 and the pole piece 39,
A gap 45 is formed between the outer periphery of the magnet 40 and the coil 38 and the bobbin 41 so that the coil 38 and the bobbin 41 can be inserted in a non-contact manner, and a magnetic field having a magnetic flux density B is formed in the gap 45. The magnet 40 is magnetized such that one end face is an S pole and the other end face is an N pole. The magnet 4
The magnetic flux of 0 is shown by a broken line in the figure.

In the power supply device 8 having such a structure, when the piston 14 is linearly reciprocated by the compressed air, the coil 38 also advances and retreats with respect to the magnetic circuit 44. _O (alternating current) occurs. The electromotive force e _O is converted into a direct current by a power supply circuit 9 and supplied to the electronic control circuit 5 and an external control device.

FIG. 3 shows an example of the power supply circuit 9. In the figure, the reference numeral 50 denotes a matching transformer,
51 is a rectifying bridge, 52 is a three-terminal regulator, 53
Is a capacitor, input terminals A and B of the matching transformer 50 are connected to the power generation unit 12 via the cable 42 (FIG. 2), and output terminals C and D are connected to the electronic control circuit 5.
Or an external control device is connected. When an AC is input to the input terminals A and B, a DC output can be obtained from the output terminals C and D.

FIG. 4 shows a configuration diagram of the electric circuit. In the figure, L and R are the impedance and resistance inside the power generation unit 12. In the figure, an input terminal A, since B load, shown as resistor R _l.

Next, the operation of the pneumatic actuator section 11 will be described in more detail with reference to FIG. FIG. 5A shows a state in which the piston 14 has moved leftward to the maximum stroke.
In this state, the piston 14 is in close proximity to the inner surface of the cover 13B, and minimizes the volume (V) of the first chamber 27a and maximizes the volume (V1) of the second chamber 27b.
Further, the air supply port 19 communicates with one of the small holes 29, and the other small hole 30 is closed by the oilless bearing 15c. In this state, the compressed air is supplied to the air supply port 1.
9, the oilless bearings 15a and 15
b enters the second chamber 27b through the gap 24, and enters the first chamber 27a through the small hole 29 and the center hole 28 (the mass flow rate of the compressed air at this time is G).

The compressed air at the supply pressure Ps is supplied to the first chamber 27a.
To the pressure Pc inside the first chamber 27a and the second pressure
And the pressure P′c inside the chamber 27b becomes the supply pressure Ps,
The pressure receiving area Ac of the piston body 14A on the cover 13B side is:
Because it is larger than the pressure receiving area As on the rod 14B side (Ac> A
s), a greater force is applied to the cover-side pressure receiving surface. Therefore, the size of the piston 14 is Ps (Ac−As) −Pa
Moves to the right under the rightward force of Aa (FIG. 5)
(B)). Here, Aa is the area of the end of the piston exposed to the atmosphere, and Pa is the atmospheric pressure. Piston 14
When the small hole 29 moves from the large-diameter hole 17 side to the small-diameter hole 18 side of the cylinder 13 due to the movement (displacement X) of the cylinder 13 and is closed by the oilless bearing 15c, the compressed air flows into the first chamber 27a. Supply is cut off. However, the piston 14 continues to move due to inertia, and when the small hole 30 coincides with the gap 25 between the oilless bearings 15c and 15d as shown in FIG. 5C, the compressed air in the first chamber 27a is released from the central hole 28.
The gas is discharged into the atmosphere through the small holes 30, the gaps 25, and the exhaust ports 20 (flow rate G). Therefore, the pressure Pc of the first chamber 27a gradually decreases to the atmospheric pressure Pa.

On the other hand, the second chamber 27 b
The volume gradually decreases as it moves to the right. Also pis
By closing the gap 24 by the ton body 14A, air
The supply port 19 is shut off. For this reason, the second chamber 27b
The internal pressure P'c gradually increases (P'c> Pc).
The piston 14 is moved leftward and returned by the pressure P'c.
(FIG. 5 (c)). Piston 14 has constant stroke to the left
When moved, the small holes 29 and 30 are
5c are closed together (FIG. 5D). further
When the piston 14 moves, the small hole 29 becomes the second chamber 27b.
Communicate with For this reason, the pressure supplied to the air supply port 19
The compressed air passes through the small hole 29-the central hole 28 and the first chamber 27.
a of the first chamber 27a.
Until the pressure Pc becomes higher than the pressure P'c of the second chamber 27b.
In FIG. 5 (a), it continues to move due to inertia.
Return to normal. Compressed air is always supplied to the air supply port 19
The piston 14 moves linearly as described above.
The coil 38 is connected to the magnetic circuit
It is reciprocated repeatedly with respect to 44. Therefore, departure
The electric part 12 is proportional to the displacement speed dx / dt of the piston 14.
And the proportional constant is C _eElectromotive force e_OCause
Load i to load R_l(Power supply circuit 9 and control equipment)
You. At this time, current i flows through coil 38 in a magnetic field.
, The electromagnetic force C proportional to the current i_i・ I occurs
And acts in a direction to hinder the movement of the piston 14 (C_i
Is a proportional constant). Therefore, self-excitation of the piston 14
Vibration is caused by this electromagnetic force C_i・ Operation including the effect of i
ing.

In such a power supply device 8, since the linear reciprocating pneumatic actuator 11 is provided, the high pressure side chamber (the first chamber 27a) and the low pressure side chamber (the second chamber 27a) are provided.
The energy conversion can be performed in a state where the chamber 27b) is closed. Therefore, energy conversion efficiency is high and air consumption can be reduced. Here, "sealing" means that the moment when the pressure equilibrates through the gap is sufficiently slow compared to the driving cycle of the actuator, although there is some air leakage from the sliding part instead of complete sealing. It shall be.

Since the first and second chambers 27a and 27b can be sealed by sliding contact between the piston 14 and the oilless bearing 15, it is necessary to press them with another member such as a spring. And a highly reliable pneumatic actuator having a reduced number of parts and abrasion of a sliding portion with the cylinder 13 or the piston 14 as compared with the conventional vane type pneumatic motor in which the vane is pressed against the inner wall of the cylinder shown in FIG. You can do it.

FIG. 6 is a sectional view showing a second embodiment of the pneumatic actuator, FIG. 7 is a sectional view taken along the line VII--VII of FIG. 6, and FIGS. 8 (a) to 8 (d) show the operation of the pneumatic actuator. FIG. In the drawings, the same components as those shown in FIGS. 2 and 3 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

In this embodiment, the piston 14 is supported using a static pressure air bearing. Cylinder 13
Is a cylinder body 13A composed of a cylinder body open at both ends, a cover 13B fixed to each end face of the cylinder body 13A,
13C. The cylinder body 13A has a center hole 62 with a constant inner diameter, and one air supply port 19 and two exhaust ports 20A and 20B are provided on the peripheral surface.
Is formed in communication with The air supply port 19 is formed in the center of the cylinder body 13A, and the first and second exhaust ports 2 are provided.
0 A and 20 B are formed on both sides of the air supply port 19.

In the center hole 62, four oilless bearings 15a to 15d are fixed to be spaced apart from each other.
a to 63c are formed. Oilless bearing 1
The gap 63a between 5a and 15b is
A, a gap 63b between the oilless bearings 15b and 15c communicates with the air supply port 19, and a gap 63c between the oilless bearings 15c and 15d communicates with the second exhaust port 20B. ing. Gap 63a, 63c
Has a width substantially equal to the hole diameter of the first and second exhaust ports 20A and 20B, and the gap 63b has a width sufficiently larger than the hole diameter of the air supply port 19.

Further, two annular grooves 64A and 64B are formed on the inner peripheral surface of the cylinder body 13A so as to be located on both sides of the gap 63b. These annular grooves 6
4A and 64B communicate with the hole 65 formed in the axial direction in the thickness of the cylinder body 13A through the communication holes 66 and 67. The hole 65 is provided on the other end surface 13b of the cylinder body 13A.
And is connected to the air supply port 19. The communication holes 66 and 67 are formed in the radial direction of the cylinder main body 13A, and the inner ends communicate with the annular grooves 64A and 64B, respectively, and the outer ends communicate with the holes 65A and 64B.
Is in communication with

The oilless bearings 15b and 15c
In the vicinity of the opposite side end, eight communication holes 68 and 69 communicating with the annular grooves 64A and 64B are formed at substantially equal intervals in the circumferential direction. These communication holes 68, 6
9 has a large diameter on the annular grooves 64A and 64B side and a small diameter on the piston 14 side.

One of the covers 13B and 13C is formed in a disk shape and hermetically closes an opening at one end of the cylinder body 13A. The other cover 13C
Is formed in a ring shape, and has a center hole 70 through which the rod 14B of the piston 14 passes through the oilless bearing 15e. An annular groove 71 is formed at the center of the inner peripheral surface of the cover 13C. Annular groove 7
Reference numeral 1 communicates with the hole 65 formed in the cylinder body 13A through a communication hole 72. Eight communication holes 73 communicating with the annular groove 71 are formed in the circumferential surface of the oilless bearing 15e at equal intervals in the circumferential direction.

The piston 14 is mounted on the cylinder body 1
3A is composed of a piston body 14A that partitions the inside into first and second chambers 27a and 27b, and a rod 14B that penetrates the center hole 70 of the cover 13C. The part 12 is attached. A first switching passage 75 that switches communication between the air supply port 19 and the first chamber 27a and communication between the first chamber 27a and the second exhaust port 20B inside the piston body 14A.
Communication between the air supply port 19 and the second chamber 27b;
A second switching passage 76 for switching the communication between the exhaust port 20A and the second chamber 27b is formed. First switching passage 7
5 has one end on the back side of the piston body 14A (the cover 13B
Side) An opening is formed on the pressure receiving surface, and the other end is opened on the peripheral surface. Second
One end of the switching passage 76 is open to the pressure receiving surface on the power generation unit side, and the other end is open to the peripheral surface.

Next, the operation of the pneumatic actuator will be described with reference to FIG. When the piston 14 has moved to the leftmost position shown in FIG. 8A, the air supply port 19 and the first chamber 27a communicate with each other through the first switching passage 75, and the first exhaust port 20A and the second exhaust port 20A communicate with each other. The chambers 27b communicate with each other via a second switching passage 76. Further, the second chamber 27b communicates with the second exhaust port 20B and is open to the atmosphere. In this state, the compressed air is supplied from the air supply port 19 through the first switching passage 75 to the first chamber 27a.
The internal pressure of the chamber 27a becomes higher than the internal pressure (atmospheric pressure) of the second chamber 27b, and the piston 14 is moved rightward (FIG. 2B). After a constant stroke, the first and second exhaust ports 20A and 20B are closed by the piston body 14A, and the first switching passage 75 is
c, and the second switching passage 76 is closed by the oilless bearing 15b (FIG. 9B).
Therefore, the supply of the compressed air to the first chamber 27a is cut off. However, since the piston 14 still moves due to inertia, the first chamber 27a communicates with the first exhaust port 20A via the first switching passage 75, and the second switching passage 7
6 communicates with the air supply port 19 via the gap 63b. Therefore, the internal pressure of the first chamber 27a gradually decreases,
The internal pressure of the chamber 27b gradually increases. When the piston 14 moves to the right by the maximum stroke (FIG. 9C), the first chamber 27a is opened to the atmosphere to communicate with the first and second exhaust ports 20A and 20B. On the other hand, since the internal pressure of the second chamber 27b is increased by the supply of the supply air Ps, the second chamber 27b moves and returns the piston 14 to the left ((d) in the same drawing). While the piston 14 is moving to the left, the first switching passage 75 connects the first chamber 27a to the air supply port 19.
The second switching passage 76 blocks communication between the air supply port 19 and the second chamber 27b, and the second chamber 27b communicates with the second exhaust port 20B. Therefore, the compressed air is supplied to the first chamber 27a through the first switching passage 75, but the inertia is maintained until the pressure in the first chamber 27a becomes higher than the pressure in the second chamber 27b. It keeps moving and returns to the initial position shown in FIG. The piston 14 repeats such a linear reciprocating motion repeatedly and continuously.

In this case, in the present embodiment, FIG.
As shown in FIG. 7, a part of the compressed air supplied to the air supply port 19 is transferred to the gap between the oilless bearings 15a to 15d and the piston body 14A through the holes 65, the communication holes 66, 67, and the annular grooves 68, 69. At the time, oilless bearing 15 is supplied through hole 65-communication hole 72-annular groove 71 at the time.
The piston 14 can be axially supported in a non-contact state with the oilless bearings 15a to 15e because the air is supplied to the gap between the rod 14B and the rod 14B. Bearing 15a
To 15e can be eliminated. Therefore,
The reliability can be further improved as compared with the above embodiment.

FIG. 9 is a sectional view showing a third embodiment of the pneumatic actuator section. In this embodiment, the other end (power generation unit side) of the cylinder body 13A is connected to the exhaust port 2.
This embodiment is different from the embodiment shown in FIG. 2 in that the number of oilless bearings 15 is set to 0 and the number of oilless bearings 15 is reduced by two, and other structures are substantially the same.

In such a structure, the cylinder 13
Can be shortened, and a small pneumatic actuator can be obtained.

FIG. 10 is a sectional view showing a fourth embodiment of the pneumatic actuator. In this embodiment, an air supply port 19 and an exhaust port 81 for an air bearing are provided in a cylinder body 13A, a center hole 70 of a cover 13C is used as a drive exhaust port 20, and a piston body 14A and a rod are used instead of an oilless bearing. Labyrinth seal 8 on the outer periphery of 14B
2 to form a dynamic air bearing. Further, the hole diameter of the cylinder body 13A is made the same over the entire length, and a hole 83 having one end opened on the back surface of the cylinder body 14A and the other end opened on the peripheral surface is provided inside the piston 14, and the first and the second holes are formed by this hole 83. 2 rooms 27a, 27b
Is communicated.

In such a structure, since a dynamic pressure air bearing is used, an oilless bearing is not required, and the number of parts can be reduced. Further, the piston 14 can be supported in a non-contact state with respect to the cylinder 13, and such wear can be eliminated.

FIG. 11 is a sectional view showing a second embodiment of the power generation unit. In this embodiment, a fixed coil 90 is provided on the inner periphery of the yoke 37, an electromotive force is generated in the fixed coil 90 with the movement of the coil 38, and the electromotive force is supplied to the power supply circuit 9 by the cable 42. Other structures are the same as those of the power generation unit 12 shown in FIG.

FIG. 12 is a sectional view showing a third embodiment of the power generation unit. In this embodiment, the yoke 37 is formed in a cylindrical body having both ends open, and two fixed coils 90
A, 90B are disposed axially apart from each other, and the piston 1
Four pole pieces 39 and a magnet 40 that form a magnetic circuit together with the yoke 37 are disposed at the tip of the pole 4. The pole pieces 39 are fixed to both magnetic pole surfaces of the magnet 40, respectively. That is, in this embodiment, the coils 90A and 90B are fixed, and the pole pieces 39 are fixed.
The magnet 40 is reciprocated to generate an electromotive force in the fixed coils 90A and 90B.

FIG. 13 is a sectional view showing a fourth embodiment of the power generation unit. In this embodiment, the yoke 37, the pole piece 39 and the magnet 4 constituting the magnetic circuit 44 are used.
0 and the piston 1
4 and the bobbin 41 of the coil 38 is
(FIG. 1), the magnetic circuit 44 is reciprocated by the piston 14 to generate an electromotive force in the coil 38.

Since there is no precedent for the power supply device according to the present invention, guidelines for designing products are unknown. Therefore, the following operation analysis was performed to obtain design guidelines. In the operation analysis, the power supply device shown in FIG. 2 was manufactured, and a nonlinear model was obtained using each variable.
This non-linear model is represented by the basic formula shown in FIG. Φ is an angle between the reciprocating direction of the piston 14 and the horizontal plane (Φ = 0 when the piston 14 is horizontal). The proportional constants C _e and C _i are theoretically equal to Bl (B is the magnetic flux density, l is the length of a conductor such as a coil).

In order to verify whether or not this nonlinear model is appropriate, a calculation result based on the basic formula (using the second-order Runge-Kutta method) was compared with a measurement result obtained by using a prototype product.

FIG. 15 shows a comparison between the measurement result and a non-linear simulation. In the figure, the solid line is the result of actual measurement, and the broken line is the result of numerical calculation using the equation of the nonlinear model shown in FIG. As shown in FIG.
The numerical calculation results agreed well with the actually measured values, and it was found that the above modeling was properly performed.

By calculating the nonlinear model numerically, the response of the pneumatic actuator can be obtained.
The relationship between the vibration state such as the frequency and amplitude and various parameters such as the mass of the piston and the supply pressure is unclear. Therefore, for the purpose of facilitating the handling of the nonlinear model, linearization is performed by giving an appropriate equilibrium point.

Equilibration

(Equation 1) Take like.

The pressure is the pressure at which the acceleration becomes zero according to the equation of motion, and the displacement is the equilibrium value at the position where the switching of the charging / discharging process occurs. When the change with respect to the equilibrium value is represented by Δ, the basic expression for linearization is as follows.

<Motion equation>

(Equation 2)

<Law of conservation of mass>

(Equation 3)

<State equation>

(Equation 4)

<Energy equation (adiabatic change)>

(Equation 5)

<Flow rate formula>

(Equation 6)

<Induced electromotive force>

(Equation 7)

<Kirchhoff's Voltage Law>

(Equation 8)

<Motion equation>

(Equation 9)

FIG. 16 shows a Laplace transform of these basic equations, which is shown as a block diagram.

FIG. 17 shows details of the relay element in FIG.

The waveform is such that one cycle T =
A periodic waveform of 2π / ω is obtained. Γ in FIG.
Is a coefficient indicating where the time until the first switching occurs is located in one cycle. For example, if the first switching occurs in a half cycle, γ = 0.5.

The transfer coefficient Zp (s) of the linear part is

(Equation 10) Becomes Here, an _{R '= R l + rC'} = C e C i.

When a transfer function Z _i (s) from the output of the relay element (external connection pressure) to the current flowing through the circuit is obtained,

[Equation 11] Becomes

[Analysis Using Fourier Series Expansion] As can be seen from the block diagram, the power generation unit is represented as a first-order lag type, but the time constant L / R ′ = L (R ₁ + r) in the present apparatus.
Is found to be very small, 0.53 [ms]. This is due to the fact that the inductance in the device is very small compared to the circuit impedance. Since this time constant is sufficiently fast with respect to the response speed of the pneumatic actuator, this is ignored and replaced by C '/ R' which is the gain of the primary delay element of the power generation unit.

Thus, the transfer function up to the linear part piston displacement and the transfer function up to the generated current are:

(Equation 12)

(Equation 13) Is simplified.

Using the obtained transfer function, a vibration state (frequency, amplitude, generated voltage amplitude) is obtained by an analysis method using Fourier series expansion. When the relay element output waveform shown in FIG. 16 is expanded into a Fourier series,

[Equation 14] Becomes

The piston displacement is determined by the gain Z _p0 (ω) and the phase θ.
By using _p (ω),

(Equation 15) Becomes

The condition for generating the self-excited vibration is expressed by the following equation from the condition that the displacement is equal at each switching time and is zero in this case.

(Equation 16)

As can be seen from FIG. 16, the first time and the second time
The condition that the direction of the movement is reversed at the time of the second switching is also a condition for generating the self-excited vibration. Since the condition of this switching direction uses the piston speed,

[Equation 17]

By ignoring the harmonic components of the Fourier series of equation (15) and using only the fundamental harmonic component and substituting it for the condition for generating self-excited oscillation, the frequency and amplitude are expressed by the following equations. You.

Analysis results using Fourier series expansion (frequency, amplitude)

(Equation 18)

[Equation 19]

On the other hand, the gain Z _i0 of the transfer function (13) to the current is:

(Equation 20) Becomes

The frequency of equation (18) is substituted into equation (20), and the amplitude of the external connection pressure to be input (from equation (14))

(Equation 21) Multiplied by the current amplitude

(Equation 22) Is obtained.

According to Ohm's law (i = e _R / R _l ), this is multiplied by an external load resistance R _l to obtain a voltage amplitude which becomes measured data in an experiment.

(Equation 23) Is obtained by the following equation. Voltage amplitude at load resistance

(Equation 24)

Based on the above-described model analysis results of the actuator in consideration of the power generation, when designing a pneumatic actuator as a part of a power supply device, a linear approximation expression of the following three main characteristics is given.

(Equation 25)

(Equation 26)

[Equation 27] Is used as a guideline for designing the actuator so that the supplied air consumption is required to be a minimum with respect to the required power generation.

Table 1 shows the symbols used in the above formula. A subscript may be added to each used symbol to indicate a particular variable.

[Table 1]

In the above embodiment, an example in which the present invention is applied to a pressure gauge is shown. However, the present invention is not limited to this, and it is needless to say that the present invention can be applied to an on-site type differential pressure / pressure transmitter. is there.

[0081]

As described above, the power supply device and the system using the same according to the present invention comprise a cylinder and a piston, and a pneumatic actuator for linearly reciprocating the piston by supplying compressed air; Since it consists of a power generation unit that generates power by converting the linear reciprocating motion of the piston into a relative reciprocating motion of the coil and the magnetic circuit, energy conversion can be performed with the high-pressure side and the low-pressure side sealed, thereby reducing air consumption. High energy conversion efficiency can be obtained with the quantity. Further, the structure is simple, the number of parts and wear are small, and high reliability can be obtained.

Further, in the present invention, since the static pressure air bearing is provided between the cylinder and the piston, the piston can be reciprocated linearly without contact with the cylinder. Therefore, high reliability can be obtained without wear.

Further, in the present invention, since the dynamic pressure air bearing is provided between the cylinder and the piston, the piston can be reciprocated linearly without contact with the cylinder. Therefore, high reliability can be obtained without wear.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a system in which the present invention is applied to a field type pressure gauge.

FIG. 2 is a sectional view of the power supply device.

FIG. 3 is a diagram illustrating a power supply circuit.

FIG. 4 is an electric circuit diagram of a power generation unit.

FIGS. 5A to 5D are diagrams illustrating the operation of a pneumatic actuator unit.

FIG. 6 is a sectional view showing a second embodiment of the pneumatic actuator section.

7 is a sectional view taken along line VII-VII of FIG. 6;

FIGS. 8A to 8D are diagrams illustrating the operation of a pneumatic actuator unit.

FIG. 9 is a cross-sectional view illustrating a third embodiment of a pneumatic actuator.

FIG. 10 is a sectional view showing a fourth embodiment of a pneumatic actuator.

FIG. 11 is a sectional view illustrating a second embodiment of the power generation unit.

FIG. 12 is a sectional view showing a third embodiment of the power generation unit.

FIG. 13 is a sectional view showing a fourth embodiment of the power generation unit.

FIG. 14 is a chart showing a nonlinear model.

FIG. 15 is a diagram showing measured values and numerical calculation results.

FIG. 16 is a block diagram obtained by linearizing a nonlinear model.

FIG. 17 is a diagram showing details of a relay block.

FIG. 18 is a sectional view of a vane type pneumatic motor.

FIG. 19 is a sectional view of an air turbine.

[Explanation of symbols]

2: pressure gauge, 8: power supply unit, 11: pneumatic actuator unit, 12: power generation unit, 13: cylinder, 14: piston, 37: yoke, 38: coil, 39: pole piece, 40: magnet, 44: magnetic circuit.

Claims (4)

[Claims] 1. A pneumatic actuator section having a cylinder and a piston for linearly reciprocating the piston by supplying compressed air, and converting the linear reciprocating motion of the piston into a relative reciprocating motion of a coil and a magnetic circuit to generate electric power. A power supply device, comprising: 2. The power supply device according to claim 1, wherein a static pressure air bearing is provided between the cylinder and the piston. 3. The power supply device according to claim 1, wherein a dynamic pressure air bearing is provided between the cylinder and the piston. 4. A system comprising: the power supply device according to claim 1, 2, or 3, and a device to be supplied to which power is supplied from the power supply device.