JP2008281100A - Fluid pressure type driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid pressure type driving device usable for driving a valve having a further larger diameter, and capable of providing the same output torque as a conventional device even if the device is miniaturized, by providing further larger output torque than output torque of a conventional Scotch yoke type driving device. <P>SOLUTION: This fluid pressure type driving device has a body 30 having cylinders 2 and 3, a valve stem 9, pistons 4 and 6 having piston rods 5 and 7, and a Scotch yoke 20. A through-hole 8 is formed in the respective piston rods 5 and 7. The Scotch yoke 20 has a pair of Scotch yoke levers 20a and 20b. The respective Scotch yoke levers penetrate through the through-hole 8. The respective pistons 4 and 6 mutually reciprocate in the opposite direction. In this reciprocating motion, the respective Scotch yoke levers respectively contact with the through-hole 8. The scotch yoke 20 rotates together with the stem 9 by couple of force of driving force of the pistons 4 and 6 by contact of these two. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hydraulic drive device for a valve that rotates like a ball valve.

Conventionally, a rack and pinion type drive device and a scotch yoke type drive device are generally known as fluid pressure drive devices. The rack and pinion type driving device is used for a small-diameter valve because of its small output torque. On the other hand, the scotch yoke type driving device has a larger output torque than the rack and pinion type driving device, and is therefore used for a large-diameter valve (see, for example, Patent Document 1).
JP-A-8-277958

  FIG. 5 shows the Scotch yoke type driving device described in Patent Document 1. In FIG. 5, reference numeral 100 is a main body, reference numeral 102 is a reciprocating shaft, reference numeral 103 is a stem (rotating shaft), reference numeral 104 is a scotch yoke lever, and reference numerals 105 and 106 are pins. The scotch yoke lever 104 is provided on the stem 103 and includes pressing portions 104a and 104b extending in the radial direction. The reciprocating shaft 102 is disposed at right angles to the axial direction of the stem 103 and has pins 105 and 106 extending in the axial direction.

  In this drive device, fluid pressure is appropriately applied to the cylinder 107 and the cylinder 108 so that the reciprocating shaft 102 reciprocates in the left-right direction in the figure, and a pin 105 or 106 provided on the reciprocating shaft 102 is provided. The pressing portion 104 a or 104 b of the scotch yoke lever 104 is pushed by the reciprocating motion of the reciprocating shaft 102, and the scotch yoke lever 104 is rotated together with the rotating shaft 103. The adjusting screws 109 and 110 provided outside the cylinders 107 and 108 are for adjusting the stroke of the reciprocating shaft 102, and by this adjustment, the rotation angle of the scotch yoke lever 104 is set to 90 degrees. The drive device rotates a valve such as a ball valve 90 degrees from fully open to fully closed and from fully closed to fully open.

  However, the structure of the above-described conventional Scotch yoke type drive device has a large output torque because the rotation shaft is rotated by only one Scotch yoke lever extending from the rotation shaft (stem) in the radial direction of the rotation shaft. There is a limit.

  The present invention has been made in view of the above-described problems of the prior art, and can obtain an output torque larger than the output torque of the conventional Scotch yoke type drive device, and thus a larger large-diameter valve. It is an object of the present invention to provide a fluid pressure drive device that can be used for driving a motor and can obtain a large output torque similar to that of a conventional drive device even if the device is downsized.

  The present invention relates to a fluid pressure driving device that operates a valve using fluid pressure as a power source, a main body having a pair of cylinders, a valve stem rotatably provided in the main body, and a slide in each cylinder. A piston having a piston rod provided movably, and a scotch yoke movably provided integrally with the valve stem, each having a through hole formed in the piston rod of each piston; The scotch yoke has a pair of symmetrical scotch yoke levers, and each scotch yoke lever passes through a through hole of a piston rod of each piston, and can slide in each cylinder. The pistons respectively provided in the reciprocating direction reciprocate in opposite directions due to the action of the fluid pressure. During the movement, each of the Scotch yoke levers comes into contact with the through hole of the piston rod, and due to the couple of the driving force of the piston transmitted to each Scotch yoke lever due to these two contacts, the Scotch yoke is Provided is a fluid pressure driving device characterized by rotating together with the stem.

  In addition, the through hole is configured by a flat upper surface, a flat lower surface, and a pair of left and right curved side surfaces protruding into the through hole, and each Scotch yoke lever contacts the curved side surface of the through hole. is doing. In addition, the shape of the curved side surface of the through hole is a curved shape corresponding to the rotational trajectory of the scotch yoke. Further, it is preferable that the curved side surface is formed such that the apex portion in contact with the scotch yoke lever is as outward as possible in a direction orthogonal to the axial direction of the piston rod. The valve stem is fitted with a pair of slide beds spaced in the axial direction of the valve stem via bearings, and the outer peripheral surface of the slide bed is in contact with the inner surface of the piston rod. It is supposed to be. Further, the length of the piston rod in the axial direction is set such that the tip of the piston rod exceeds the center of the stem when the piston is positioned most outward in the cylinder.

  According to the present invention, the output torque of the conventional scotch yoke type driving device can be obtained to obtain a larger output torque, so that it can be used for driving a larger large-diameter valve, and the device can be downsized. A large output torque similar to that of a conventional drive device can be obtained.

Hereinafter, the best mode for carrying out a fluid pressure driving apparatus according to the present invention will be described with reference to the drawings. FIG. 1 shows a cross-sectional view of a fluid pressure drive device according to the present invention, and FIG. 2 shows a longitudinal cross-sectional view thereof. As shown in FIGS. 1 and 2, the fluid pressure driving device 1 is used to operate a valve (not shown) such as a ball valve. The fluid pressure drive device 1 has a pair of cylinders 2 and 3 on both sides of the main body 30. A piston 4 is slidably provided in a cylinder 2 located on the right side in FIG. 1, and a piston rod 5 is attached to the piston 4. Similarly, a piston 6 is slidably provided in the cylinder 3 located on the left side in FIG. 1, and a piston rod 7 is attached to the piston 6. As illustrated, the piston 4 and the piston 6 are slidably provided in each cylinder in a state of facing each other. In FIG. 1, the left cylinder 3 portion is partially omitted.

FIG. 3 shows a perspective view of the pistons 4 and 6. As shown in the figure, pistons 4 and 6 have piston rods 5 and 7 attached to their bottoms. The piston rods 5 and 7 are long in the axial direction of the piston rods 5 and 7 on the tip side. Each through hole 8 is formed. The through hole 8 includes a flat upper surface 8 a, a flat lower surface 8 b, and a pair of left and right curved side surfaces 8 c and 8 d protruding into the through hole 9. The curved side surfaces 8c and 8d have a curved shape corresponding to the rotational trajectory of the scotch yoke 20 described later.

Also, the axial length of the piston rods 5 and 7 is such that the distance between the base ends and the distal ends of the piston rods 5 and 7 when the pistons 4 and 6 are located most outward in the cylinders 2 and 3 is as follows. It is set to be longer than the distance between the base ends of the piston rods 5 and 7 and the center of a stem 9 described later. In other words, the lengths of the piston rods 5 and 7 in the axial direction are such that when the pistons 4 and 6 are located at the outermost positions in the cylinders 2 and 3, the tip ends of the piston rods 5 and 7 The length exceeds the center.

As shown in FIGS. 1 and 2, a valve stem 9 extending in the vertical direction of the apparatus 1 is rotatably provided at the center of the main body 30 of the apparatus 1. It is inserted through a stem hole 31 that fits into the valve body that does not. A stopper 32 for determining the opening / closing position of the valve is provided on the outer periphery of the stem 9 located above the stem hole 31. A pair of rectangular slide beds 10 and 11 that are spaced apart from each other in the vertical direction (axial direction) are fitted via a bearing 21 at a substantially central position of the stem 9. The outer peripheral surfaces of the slide beds 10 and 11 are in contact with the inner surfaces of the piston rods 5 and 7. The outer surfaces of the piston rods 5 and 7 are in contact with the inner peripheral surfaces of the cylinders 2 and 3. Accordingly, the piston rods 5 and 7 can be slid in a state where the inner surfaces thereof are in contact with the outer peripheral surfaces of the slide beds 10 and 11 and the outer surfaces thereof are in contact with the inner peripheral surfaces of the cylinders 2 and 3. It has become. Each component in contact with the outer peripheral surface of the stem 9 is provided with a thrust bearing, shim, spacer, and the like.

The stem 9 is provided between the slide bed 10 and the slide bed 11 so that the scotch yoke 20 can rotate integrally with the stem 9. As shown in FIGS. 1, 2, and 4, the scotch yoke 20 has a pair of scotch yoke levers 20a and 20b that are symmetrical about the center. The scotch yoke lever 20 a passes through the through hole 8 of the piston rod 5, and the scotch yoke lever 20 b passes through the through hole 8 of the piston rod 7, and the scotch yoke 20 is integrated with the stem 9. It is provided so that it can be rotated.

In the driving device 1 of the present invention, when a fluid pressure is appropriately applied in the cylinder 2 and the cylinder 3 and the piston 4 moves outward (rightward in FIG. 1) in the cylinder 2, the piston 6 is externally moved in the cylinder 3. When the piston 4 moves inward (leftward in FIG. 1) in the cylinder 2, the piston 6 moves inward (rightward in FIG. 1) in the cylinder 3. The pistons 4 and 6 reciprocate so as to move.

That is, the piston 4 and the piston 6 reciprocate in opposite directions. When the piston 4 moves outward (rightward in FIG. 1) in the cylinder 2 and the piston 6 moves outward (leftward in FIG. 1) in the cylinder 3, the scotch yoke lever 20a moves to the piston rod 5 The scotch yoke lever 20b contacts the curved side surface 8d of the through hole 8 of the piston rod 7, and the scotch yoke 20 rotates together with the stem 9 in the clockwise direction. Move. On the other hand, when the piston 4 moves inward (leftward in FIG. 1) in the cylinder 2 and the piston 6 moves inward (rightward in FIG. 1) in the cylinder 3, the Scotch yoke lever 20 a moves to the piston rod 5. The scotch yoke lever 20b contacts the curved side surface 8c of the through hole 8 of the piston rod 7, and the two contacts cause the scotch yoke 20 together with the stem 9 to rotate counterclockwise. Rotate. That is, the scotch yoke 20 includes the driving force of the piston 4 transmitted to the scotch yoke lever 20a by the contact between the scotch yoke lever 20a and the through hole 8 of the piston rod 5, and the through hole 8 of the scotch yoke lever 20b and the piston rod 7. The stem 9 is integrated with the scotch yoke 20 by the rotation of the scotch yoke 20 by the couple of the driving force of the piston 6 transmitted to the scotch yoke lever 20b by the contact with the scotch yoke lever 20b. The valve is driven to rotate, and a valve (not shown) is opened and closed.

In the conventional scotch yoke type drive device, as shown in FIG. 5, the rotation shaft is rotated by only one scotch yoke lever. However, in the drive device according to the present invention, the scotch yoke 20 is centered on the central portion thereof. A pair of scotch yoke levers 20a and 20b that are symmetrical to each other, and the scotch yoke 20 is rotated by a couple of force generated by the two driving forces of the pistons 4 and 6 transmitted to the scotch yoke levers 20a and 20b. Therefore, a very large torque can be obtained as compared with the conventional Scotch yoke type driving device.

Also, the shape of the curved side surfaces 8c and 8d shown in the figure is such that the apex part in contact with the scotch yoke lever is the central part of the thickness of the piston rods 5 and 7. If it is formed so as to be as outward as possible in the direction orthogonal to the axial directions of 5 and 7, even greater torque can be obtained. Furthermore, the illustrated scotch yoke lever extends in the axial direction with the same diameter, but the diameter increases toward the tip direction, that is, the scotch yoke lever has a tapered shape. In this case, a larger torque can be obtained.

Further, in the conventional fluid pressure type driving device, the stem is rotated 90 degrees in order to change the valve from the fully closed position to the fully opened position. Therefore, the open position and the closed position of the Scotch yoke lever are symmetrical with respect to the intermediate position. If the position is θ = 45 °, the output torque Ta at both ends is
Ta = Fe / cos ² 45 ° · η = 2Feη.
F is the force generated by the rotational force of the handle (or acting on the piston by the fluid pressure), e is the eccentric distance between the rod and the stem operating with the piston, and η is the efficiency.

On the other hand, in the driving device of the present invention, the scotch yoke levers 20a and 20b can be obtained by setting the center position in the width direction of the scotch yoke levers 20a and 20b to θ = 45 ° with respect to the intermediate position at the open position and the closed position. The open and closed positions are symmetrical with respect to the intermediate position, and each position can be θ = 45 ° + the width of the scotch yoke lever / 2.

Here, for example, when the width / 2 of the scotch yoke lever is 5 °, the open position and the closed position of the scotch yoke levers 20a and 20b are symmetrical with respect to the intermediate position, and each position is θ = 50 °. The output torque Tb in this case is
Tb = Fe / cos ² 50 ° · η = 2.42Feη, and the high output torque can be increased by 21% with respect to the conventional output torque Ta.

In the identification paragraph “0021”, the output torque with a scotch yoke lever width / 2 of 5 ° is described, but now the scotch yoke width / 2 is 7 ° with the width of the scotch yoke lever as the center. When it is 3 °, the output torque Tc is
Tc = Fe / cos ² 52 ° · η = 2.64Feη, and higher output can be obtained. In the case of a ball valve, since the required torque is larger in the case of opening from the closed state than in the case of opening from the closed state, it is more effective if it matches the characteristics of the valve. This is the same effect as the shape of the scotch yoke lever described in the identification paragraph “0018” is made thicker.

Further, if the apex portions of the curved side surfaces 8c and 8d of the piston rod in contact with the scotch yoke lever are moved outward from the center of the rod by f as shown in FIG. 1, and F is set to F1,
Td = F1e / cos ² 52 ° · η = F1 / F · Tb, and high output torque increased by F1 / F from the output torque Tb can be obtained.

Further, in the driving device of the present invention, when the piston rods 5 and 7 have an axial length when the pistons 4 and 6 are located at the outermost positions in the cylinders 2 and 3, the tip ends of the piston rods 5 and 7 are Since the length exceeds the center of the stem 9, the piston rods 5 and 7 receive a force on the stem 9 side by the rotation of the scotch yoke levers 20a and 20b, but the pistons 4 and 6 can operate without any trouble. .

The slide beds 10 and 11 are attached to the stem 9 via bearings 21 and receive the same load from the pair of pistons 4 and 6, so the stem 9 receives only a couple of loads and operates smoothly. It can be performed. The piston rods 5 and 7 can be slid in a state where the inner surfaces thereof are in contact with the outer peripheral surfaces of the slide beds 10 and 11 and the outer surfaces thereof are in contact with the inner peripheral surfaces of the cylinders 2 and 3. Therefore, smooth operation can be performed.

FIG. 1 is a cross-sectional view showing an embodiment of a fluid pressure driving device according to the present invention. FIG. 2 is a longitudinal sectional view showing the above embodiment. FIG. 3 is a perspective view showing an example of a piston applicable to the above embodiment. FIG. 4 is a perspective view showing an example of a scotch yoke applicable to the above embodiment. FIG. 5 is a cross-sectional view showing an example of a conventional Scotch yoke type driving device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fluid pressure drive device 2 Cylinder 3 Cylinder 4 Piston 5 Piston rod 6 Piston 7 Piston rod 8 Through-hole 8a Upper surface 8b Lower surface 8c Curved side surface 8d Curved side surface 9 Stem 10 Slide bed 11 Slide bed 20 Scotch yoke 20a Scotch yoke lever 20b Scotch yoke Lever 30 Body 31 Stem hole 32 Stopper

Claims (6)

In a fluid pressure drive device that operates a valve using fluid pressure as a power source,
A main body having a pair of cylinders;
A valve stem rotatably provided in the main body,
A piston having a piston rod, slidably provided in each cylinder;
A scotch yoke provided movably integrally with the valve stem;
A through hole is formed in each piston rod of each piston,
The scotch yoke has a pair of symmetrical scotch yoke levers, and each scotch yoke lever passes through a through hole of a piston rod of each piston,
The pistons slidably provided in the cylinders reciprocate in opposite directions due to the action of the fluid pressure. During the reciprocation, the scotch yoke levers are moved to the pistons. The fluid pressure is characterized in that the scotch yoke rotates together with the stem by a couple of driving forces of the piston transmitted to the respective scotch yoke levers due to contact with the through holes of the rod, respectively. Drive device. The through hole is composed of a flat upper surface, a flat lower surface, and a pair of left and right curved side surfaces protruding into the through hole, and each of the Scotch yoke levers contacts the curved side surface of the through hole. The fluid pressure drive device according to claim 1. The fluid pressure drive device according to claim 2, wherein the shape of the curved side surface of the through hole is a curved shape corresponding to the rotational trajectory of the scotch yoke. The shape of the curved side surface is formed such that the apex portion in contact with the scotch yoke lever is as outward as possible in a direction orthogonal to the axial direction of the piston rod. 4. The fluid pressure drive device according to 3. A pair of slide beds spaced apart in the axial direction of the valve stem are fitted to the valve stem via bearings, and the outer peripheral surface of the slide bed is in contact with the inner surface of the piston rod. 5. The method according to claim 1, wherein:
The fluid pressure drive device according to any one of the above. The length of the piston rod in the axial direction is set such that the front end of the piston rod exceeds the center of the stem when the piston is positioned most outward in the cylinder. The fluid pressure drive device according to any one of claims 1 to 5.

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