JP3142721B2 - Explosion-proof pressure sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-resistant explosion-proof pressure sensor, and more particularly to an improvement in a wiring device.
The explosion-proof structure means that when a fire occurs inside the case 1, for example, when electric components inside the case 1 burn, the flame does not leak out of the case 1 and therefore there is an ignitable gas around the case 1. It does not catch fire. The dimensions of the connection between the case, the cover, the pressure receiving portion or the cable gland are defined by the shape or size of the pressure sensor.

[0002]

2. Description of the Related Art FIG. 3 is a front view showing a structure of a conventional explosion-proof pressure sensor with a part thereof removed, and FIG. 4 is a longitudinal sectional view of a cable gland. In FIG. 3, 1 is a cylindrical case,
13 is a cable gland, 22 is a pressure receiving part. As shown in FIG. 4, the cable gland 13 includes a base 13a and a clamp 13b. The base portion 13a has a screw portion 14 for connecting to the case 1 at one end, and a female screw 30 at the other end. The screw portion 31 of the clamp portion 13b is screwed into the female screw 30. Base part 13
A pressure-resistant rubber packing 18 for controlling a seal between the a and the clamp portion 13b is provided. The cable gland 13 having such a configuration is disposed along the line intersecting the axis of the case 1 with respect to the case 1 with respect to the position of the terminal plate (not shown). The circumference is connected on the dividing line. In the circumference of the case 1, a cylindrical portion 32 is integrally formed on a line extending radially from the center. A female screw 20 is provided at an outer end of the cylindrical portion 32. The pressure receiving portion 22 has a pressure detector 24 at one end, and has a screw portion 25 on the outer periphery of the pressure receiving portion 22 to be screwed with the female screw 20 of the cylindrical portion 32. A terminal plate 10 is provided in the case 1, and a terminal block 6 is provided on the terminal plate 10. The cable 16 is inserted into the cable gland 13 from outside the case 1, guided by the cable gland 13, and guided into the case 1. In this state, each line 16a, 16b, 1 of the cable 16 is
The terminal strips 28 attached to the tips of 6c and 16d are fixed to the terminal block 6.

[0003]

Since the conventional explosion-proof pressure sensor is configured as described above, when miniaturizing the sensor, first, the radius of the cylindrical shape of the main case 1 is shortened. There is a need. Therefore, cable gland 1
3, the cable 16 introduced into the case 1 must be bent at a steep angle in the case 1, and in such a state where the cable 16 is forcibly bent, each line 16a, 1
Since the ends of the terminals 6b, 16c, and 16d, that is, the positions of the terminal strips 28, are sequentially shifted, there is a problem that wiring work is extremely difficult. Further, since the cable gland 13 protrudes long on the circumference of the case 1 in the direction of its secant line, there is a problem that it is necessary to secure a sufficient mounting place for the pressure sensor. Further, since the pressure receiving portion 22 is provided so as to protrude outward from the case 1 on a line crossing the circumference from the center of the case 1, a large mounting space is required. Further, as the size of the case 1 is reduced, there is a problem that an excessive force is applied to the cable 16 when the terminal strip 28 of the cable 16 is attached to the terminal block 6, and the reliability of the wiring work may be lost. ing.

According to the first aspect of the present invention, as the pressure-resistant explosion-proof pressure sensor is downsized, even if the connection space is reduced, the wiring work can be performed reliably without applying excessive force to the cable. The purpose is to do.

According to a second aspect of the present invention, as in the first aspect, the wiring work can be reliably performed without applying an excessive force to the cable even if the connection space is reduced due to the miniaturization of the pressure-resistant explosion-proof type pressure sensor. It is another object of the present invention to make it possible to further reduce the size of the cable gland part.

According to a third aspect of the present invention, the pressure receiving portion mounting portion of the pressure-resistant explosion-proof pressure sensor is reduced in size, the sealing performance of the pressure receiving portion mounting portion is ensured, and the mounting of the pressure receiving portion can be further strengthened. The purpose is to do.

[0007]

According to a first aspect of the present invention, there is provided a cylindrical case, an electric circuit portion accommodated in the case, and a terminal plate disposed so as to intersect the axis of the case. And a terminal block fixed to one end side of the case and electrically connected to the electric circuit section, a cover removably attached to one end of the case and covering the terminal block, And a tubular cable gland extending outwardly of the case along the axis of the case and guiding the cable from outside the case to the terminal block, and a circle of the case from the axis of the case. A pressure receiving portion screwed to the case and housed inside the case on a line extending in the circumferential direction.

According to a second aspect of the present invention, in the first aspect, the size of the cable gland is reduced, and the screw portion (14) is screwed into a screw cylinder extending into the case of the cable gland, and the base portion of the cable gland is formed. A mechanism for pressing a pressure-resistant packing having the same configuration as that of (13a) by a screw of a clamp portion is provided.

According to a third aspect of the present invention, in accordance with the first aspect, the mounting portion of the pressure receiving portion is reduced in size, and the pressure receiving portion is screwed to a screw cylinder extending inside the case, so that the space between the pressure receiving portion and the screw cylinder is provided. To O
A ring is provided, the case is engaged with the pressure receiving part in a direction intersecting with the axis of the pressure receiving part, and a set screw is applied so as to engage with the concave part provided in the pressure receiving part. It is what governed.

[0010]

According to the first aspect of the present invention, the cable is drawn into the case from the other end along the axis of the case, and is connected to the terminal block at one end of the case.

According to a second aspect of the present invention, similarly to the first aspect, the cable is drawn into the case from the other end along the axis of the case, and is connected to the terminal block at one end of the case. The screw portion is screwed into a screw tube extending into the case of the cable gland, and a pressure-resistant packing having the same configuration as the base portion of the cable gland is pressed by the screw portion of the clamp portion.

According to a third aspect of the present invention, similarly to the first aspect, the cable is drawn into the case from the other end along the axis of the case, and is connected to the terminal block at one end of the case. The pressure receiving portion is screwed into a screw cylinder extending inside the case. A seal between the pressure receiving portion and the screw cylinder is secured by an O-ring. Further, locking of the pressure receiving portion to the case is performed by a set screw engaged with a concave portion provided in the pressure receiving portion.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a pressure-resistant explosion-proof pressure sensor according to the present invention will be described below with reference to the drawings. Reference numeral 1 denotes a cylindrical case molded by metal, for example, aluminum die-casting. The case 1 has an opening 2 at one end and a wall 3 at the other end of the case 1. Reference numeral 4 denotes an electric circuit portion accommodated in the cylindrical case 1, and the electric circuit portion 4 is constituted by a printed circuit board constituting an electric circuit. The electric circuit portion 4, that is, the printed circuit board is disposed along the axis of the case 1. Reference numeral 5 denotes a terminal plate which is arranged on the opening side by devising the arrangement position inside the case 1, and the surface of the terminal plate 5 is orthogonal to the axis of the case 1. Reference numeral 6 denotes a terminal block attached to one surface of the terminal plate 5, that is, the surface of the case 1 on the side of the opening 2, and is electrically connected to the electric circuit unit 4. Reference numeral 7 denotes a cover that covers the opening 2 of the case 1. A screw 8 is provided on the outer periphery of the cover 7, and the screw 8 is screwed with a female screw 9 provided on the inner periphery of the opening 2 of the case 1. It has been like that. Reference numeral 10 denotes a seal member that manages a seal between the case 1 and the cover 7. In addition, 10 may be located outside the threaded portions 8 and 9 by an O-ring or the like. The other end of the case 1 is provided with a screw hole 12 formed by a guide wall 11 that penetrates the wall 3 and extends along the axis of the case 1. Reference numeral 13 denotes a cable gland, which is formed in a tubular shape by a hollow member. One end of the cable gland 13 is formed with a screw portion 14 to be screwed with the screw hole 12, and the other end is provided with a clamp 15. Cable gland 13
Is for guiding the cable 16 from outside the case 1 to the inside thereof. A recess 17 is formed at an end of the screw hole 12 in the case 1, and a rubber pressure-resistant packing 18 that manages a seal between the case 1 and the cable gland 13 is provided in the recess 17. Reference numeral 19 denotes a set screw for screwing the cable gland 13 into contact with the case 1 to prevent loosening of the cable gland 13 with respect to the case 1. A screw hole 20 is provided on the outer peripheral wall of the case 1, and the screw hole 20 is formed in the case 1 along a radial line extending from the axis of the case 1 to the circumference of the case 1. Formed by Reference numeral 22 denotes a pressure receiving portion. The pressure receiving portion has a pressure receiving tube 23 and a pressure detecting element 24 attached to one end of the pressure receiving tube 23.
On the outer periphery of 3, a screw portion 25 screwed with the screw hole 20 is provided. An O-ring 26 is mounted between the guide wall 21 and the pressure receiving cylinder 23. The O-ring 26 secures a seal between the pressure receiving portion 22 and the screw cylinder 20. The screw part 25 of the pressure receiving part 22 is screwed to the screw cylinder 20 extending inside the case 1. The set screw 27 is screwed into the case 1, and its tip is a set screw for preventing loosening whose abutment comes into contact with the concave portion of the pressure receiving portion 22. 28 is each line 16a, 16 of the cable 16
Terminal strips 29 fixed to one ends of b, 16c and 16d, and 29 are fastening screws for fastening the terminal strip 28 to the terminal block.

In the above configuration, the cable gland 13
Is connected to the case 1 in a state where one end of the cable gland 13 enters the case 1 in advance with a screw cylinder 12 extending into the case 1. Each line 1 of the cable 16
6a, 16b, 16c, and 16d have terminal pieces 2
8 is attached. Cable 16 is cable gland 1
3, is drawn into the case 1 along the axis of the case 1, and further drawn out to one end of the case 1. Each line 16a, 16b, 16 of the cable 16
c and 16 d are bent along the surface of the terminal plate 5 and are expanded around the cable gland 13. Therefore, the end portions of the respective terminal pieces 28 are aligned at substantially the same position, that is, at substantially the same height. In this state, each terminal strip 28 is fastened to the terminal block 6 by a fastening screw 29.

[0015]

As described above, according to the first aspect of the present invention, the tubular cable gland for guiding the cable from the outside of the case to the terminal block is provided at the other end of the case, and the axial line of the case is provided. And the pressure receiving portion is screwed to the case and housed inside the case on a line extending in the circumferential direction of the case from the axis of the case. When attaching the cable to the terminal block with the cable pulled into the case, the direction in which the cable is pulled out to the terminal block matches the pushing direction of the cable, so the cable can be easily pulled out, and the ends of the cable are dimensionally aligned. Therefore, it is very easy to attach the cable to the terminal block, and there is an effect that no excessive force is applied to the cable.

According to a second aspect of the present invention, in the first aspect, a screw portion is provided on an outer periphery of one end of the cable gland, and the screw portion is attached to a screw cylinder constituting a base portion structure of the cable gland extending into the case. Since the screw gland is screwed, the size of the cable gland protruding from the case is extremely shortened, so that there is an effect that the size can be easily reduced.

According to the third aspect of the present invention, in the first aspect, the pressure receiving portion is screwed into a screw cylinder extending inside the case,
An O-ring is provided between the pressure receiving portion and the screw cylinder, and the case is engaged with the pressure receiving portion in a direction intersecting with the axis of the pressure receiving portion, and a set screw for preventing the pressure receiving portion from being loosened from the case. Since the size of the pressure receiving part protruding from the case is extremely shortened, the size can be easily reduced, and the sealing performance between the pressure receiving part and the case part can be improved to ensure dustproof and drip-proof properties. There is an effect that can be.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a pressure-resistant explosion-proof pressure sensor according to the present invention.

FIG. 2 is a front view showing the pressure-resistant explosion-proof pressure sensor in FIG. 1 with its cover removed.

FIG. 3 is a front sectional view of a conventional pressure-resistant explosion-proof pressure sensor.

FIG. 4 is a longitudinal sectional view of the cable gland in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Case 4 Electric circuit part 5 Terminal board 6 Terminal block 7 Cover 12 Screw cylinder 13 Cable gland 13a Base part 13b Clamp part 14 Screw part 16 Cable 18 Pressure-resistant packing 20 Screw hole 21 Guide wall 22 Pressure receiving part 22a Depression 24 Pressure detecting element 25 Screw part 26 O-ring 27 Set screw

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuhide Yoshikawa 1-12-2 Kawana, Fujisawa-shi, Kanagawa Prefecture Inside the Fujisawa Plant of Yamatake Honeywell Co., Ltd. (72) Inventor Shunji Ichida 1-1-12 Kawana, Fujisawa-shi, Kanagawa No.2 Yamatake Honeywell Co., Ltd. Fujisawa Plant (56) References JP-A-7-311108 (JP, A) JP-A-6-129928 (JP, A) Real opening Hei 1-124537 (JP, U) Real opening Hei 5-73551 (JP, U) JP-A 2-89320 (JP, U) JP-A 60-141531 (JP, U) Tokuyo Sho 64-500538 (JP, A) (58) Fields surveyed (Int) .Cl. ⁷ , DB name) G01L 19/14 G01D 11/24

Claims (3)

(57) [Claims] 1. A case (1) having a cylindrical shape, an electric circuit portion (4) housed in the case (1), and an axis intersecting with the case (1). A terminal plate (5), and a terminal block (6) that is fixed at one end of the case (1) and is electrically connected to the electric circuit portion (4) in the terminal plate (5). A cover (7) detachably attached to one end of the case (1) and covering the terminal block (6); and a cover (7) provided on the other end side of the case (1). A tubular cable gland (13) extending along the line to the outside of the case (1) and guiding the cable (16) from outside the case (1) into the case (1); ) Is screwed into the case (1) on a line extending in the circumferential direction of the case (1) from the axis of the case (1). And a pressure receiving portion (22) housed inside the case (1). 2. The cable gland clamp portion (1).
3b) is provided with a screw portion (14) on the outer periphery of one end, and screw this screw portion to a screw cylinder (12) extending into the case (1), which is equivalent to the base portion (13a) of the cable gland. The pressure-resistant explosion-proof pressure sensor according to claim 1, wherein the pressure-resistant packing (18) is pressed by the screw portion (14). 3. The pressure receiving section (22) is provided in the case (1).
Screwed into the screw cylinder (20) extending inside, and
An O-ring (26) is provided between 2) and the screw cylinder (20), and the case (1) intersects the pressure receiving portion (22) with the axis of the pressure receiving portion (22). 2. A pressure-resistant explosion-proof type according to claim 1, wherein the pressure receiving portion is provided with a recess, and a set screw engaging with the case is provided so as to engage with the recess. Pressure sensor.