JPH0518481Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The present invention relates to the improvement of a rotary actuator operated by hydraulic or pneumatic pressure, etc. By adopting a particularly special structure, the piston rod is omitted, and the rotary actuator is compact. ,
The present invention relates to a rotary actuator that is lightweight, low cost, has increased torque, etc., and is capable of responding to increased loads.

[Prior art]

The conventional general rotary actuator is
As shown in the figure, a pressure source 1 such as a pump, a tank 2
A 4-port switching valve 4 is interposed between the rotary actuator 3 and the rotary actuator 3, and in the state shown in the figure, working fluid such as pressure oil and compressed air discharged from the pressure source 1 passes through the flow rate adjustment valve 5 and enters the cylinder chamber 6. A portion flows into the cylinder chamber 8 through the pipe 7, and enters the cylinder 9,
Pistons 11 and 12 fitted in 10 are indicated by arrows
The fluid discharged from the cylinder chambers 13 and 14 by the sliding of the pistons 11 and 12 is configured to be discharged from the four-port switching valve 4 into the tank 2 through the flow rate control valve 15. ing.

When moving the piston in the opposite direction, the 4-port switching valve 4 is switched in the direction of arrow Y. By switching the fluid path in this way, the pistons 11, 1
2 and a piston rod 16 that connects both pistons.
move back and forth as a unit.

On the other hand, a clevis pin 18 implanted in a trunnion 17 fitted and fixed to the piston rod 16 is inserted into a yoke groove 22 of a yoke 21 fixed to a drive shaft 20 rotatably inserted into the cylinder body 19. , 12 reciprocate from side to side, the clevis pin 18 slides inside the yoke groove 22 while pushing the side wall of the yoke groove 22, causing the yoke 21 to swing, and the butterfly valve and ball valve connected to the drive shaft 20 , and other driven bodies rotate. A mechanism that uses such a yoke to convert reciprocating motion into rotational motion is called a Scotch yoke mechanism.

Since such a conventional rotary actuator requires a piston rod 16 for connecting pistons 11 and 12 as shown in the figure, it has various drawbacks as described below.

(1) Since the piston rod 16 passes through the yoke chamber 23 in which the yoke 21 is provided, the cylinder body 1
9 requires a gland packing 24, which causes a large mechanical loss, the torque obtained is small compared to the size of the equipment body and the hydraulic/pneumatic pressure used, and the packing life becomes a problem, and the number of parts is large, resulting in high cost. It is.

(2) Since the cylinder chamber 6 and the yoke chamber 23 have to be arranged separately and side by side, the size becomes large in the longitudinal direction, especially in the case of a double-sided piston type as shown in the first figure.

(3) In order to apply large torque to the drive shaft 20, it is necessary to increase the distance between the axes of the drive shaft 20 and the clevis pin 18, but since the clevis pin 18 must be provided on the axis of the piston rod 16, the drive The shaft 20 has to be largely eccentric from the axis of the piston rod. Therefore, the actuator becomes larger in the lateral direction as well. Also, for the same reason, the piston stroke increases,
In the case of a single-acting type, a large diameter and long spring is required to reduce the spring constant of the coil spring used for return.

(4) When using a coil spring for the return, in order to make the piston slide, it is necessary to apply a pressing force to overcome the force of the coil spring in addition to the rotating load of the valve, etc. In the case of rotary actuators, this problem was solved by increasing the diameter of the piston and cylinder, which resulted in the rotary actuator having a large diameter.

Furthermore, even when using hydraulic and pneumatic pressure for return, in order to increase the driving torque, it is necessary to increase the diameter of the piston and cylinder in the same way as described above.

(5) In order to reduce weight, it is necessary to reduce the wall pressure of the piston, but since the width of the piston cannot be reduced below a certain level, recesses 25 are provided in the side walls of the pin struts 11 and 12. However, this increases the volume inside the cylinder chambers 6, 14, and when pneumatic pressure is used, the consumption of working fluid increases, which is uneconomical.

As an example of a rotary actuator that can solve these problems, for example,
A rotary actuator described in Japanese Patent No. 58-24605 is known. This was filed by the present applicant, and is a rotary actuator in which the linear motion of a piston that reciprocates in sliding contact with the inner wall of a cylinder is converted into the rotational motion of a drive shaft provided with a yoke using a Scotch yoke mechanism. 2
A trunnion pin fixed to the intermediate rib and a drive shaft are respectively opposite to the axis of the cylinder. While eccentric to the side,
A drive shaft is passed through the hollow part of the piston and attached to the cylinder, and a trunnion pin is engaged with a yoke groove of a yoke fixed to the drive shaft, so that the drive shaft is rotated by the reciprocating movement of the piston.
It is a rotary actuator that does not require a piston rod, and it can be made smaller and lighter, and it can obtain a large driving torque compared to its size, improving mechanical efficiency. It is excellent in that it can be

Therefore, such a rotary actuator is
It has come to be used for various valve operations.

By the way, such a rotary actuator is
It is operated by pneumatic pressure, etc., but if pneumatic pressure is used for both reciprocating motion, two control valves are required, and the pneumatic circuit and the electric circuit to control it become complicated and expensive, so it is not normally used. During forward or backward movement, a return spring is attached instead of the pneumatic drive.

[Problem that the invention attempts to solve]

However, when such a return spring is used, the force of this spring always acts in a direction opposite to the air pressure, and a rotary actuator with a large driving force is required. This ultimately leads to an increase in the size of the rotary actuator, thereby negating the advantage of the rotary actuator, which does not require a piston rod, and whose greatest advantage is its small size.

In particular, when the rotary actuator that does not require a piston rod is used to drive a butterfly valve, when the butterfly valve is closed, and when the valve is opened from a fully closed state,
Because the extremely large load is applied, it becomes necessary to change the capacity of the rotary actuator according to the capacity of the butterfly valve being driven, and this may be ineffective to some extent because the rotary actuator uses high-precision parts. This is unavoidable and uneconomical.

[Means for solving problems]

The purpose of this invention is to solve the problems inherent in the conventional rotary actuator as described above, and it uses a sub-piston and sub-cylinder that are much cheaper than the main body of the rotary actuator. Installed in series with the rotary actuator,
The cylinder of the sub-piston can be separated from the cylinder of the rotary actuator so that the valve driving force can be increased without increasing the price and the sub-piston as mentioned above can be changed to a larger one according to the valve capacity. It is made into a separate body that can be separated.

In order to increase the valve driving force, it is possible to connect multiple sub-pistons in series as described above, but in this case, the length of the actuator becomes longer by an integral multiple of the stroke of the sub-piston, and the rotary actuator The advantage of downsizing is lost. In this regard, the piston diameter has an effect on the driving force as the square of its diameter, so if you make it possible to replace sub-pistons with different diameters as described above, you can increase the driving force without increasing the volume of the actuator too much. Therefore, the advantages of the rotary actuator that does not require a piston rod can be fully utilized.

Furthermore, if the sub-piston as described above is connected to the piston of the rotary actuator as one unit, if the sub-cylinder on the sub-piston side and the main cylinder on the rotary actuator side are even slightly misaligned, both pistons will be damaged. Since it will no longer be able to slide, the machining accuracy will have to be increased more than necessary.
In the present invention, the sub-piston is separated from the piston on the rotary actuator side.

〔Example〕

Next, embodiments embodying the present invention will be described in detail with reference to the accompanying drawings starting from FIG. 2 to provide an understanding of the present invention.

Here, Fig. 2 is a plan view of a rotary actuator equipped with a return coil spring, which is an embodiment of the present invention, and Fig. 3 is a sectional view of the same side (with the main piston stroked to the far right ), FIG. 4 is an end view taken along the line A--A in FIG. 3, and FIG. 5 is a perspective view of the main piston that can be used in the same embodiment.

In these figures, 26 is a cylindrical main cylinder, and its right opening is a sub cylinder 2, which will be described later.
6b via a sealing member 72, and the left opening is closed by a spring case 26a, forming a cylinder chamber 28 inside. Inside the cylinder chamber 28,
A seal member 3 is attached to the inner wall 29 of the main cylinder 26.
A main piston 31 that is slidable in the axial direction of the main cylinder 26 is fitted into the main cylinder 26 while being in contact with the main piston 31 via the main cylinder 26 .

Therefore, the cylinder chamber 28 contains the main piston 31
The right cylinder chamber 28a and the left cylinder chamber 28
It is sealed in a sealed manner.

Inside the casing wall of the main cylinder 26, a pressure source 1 shown in FIG.
Fluid introduction holes 100 and 101 are provided to introduce or lead out working fluid such as compressed air discharged from the cylinder chambers 28a and 28b.

32 and 33 are the fluid introduction holes 100, 10.
1, the working fluid is transferred to the right cylinder chamber 28a.
and a fluid introduction hole which is an example of a nozzle hole for introducing or leading out the left cylinder chamber 28b.

As shown in FIGS. 3 and 5, the main piston 31 has two disc-shaped sliding contact parts 34 and 35 that slide while contacting the inner wall of the cylinder 26, and the intermediate rib 3.
6 and 37, and there is a hollow part W in the middle.
It has a hollow structure and is coaxially attached to the main cylinder 26.

A clevis pin 40 is fitted and fixed in a through hole 39 formed in a bifurcated clevis 38 formed integrally with the rib 37. The mounting position of the clevis pin 40 is at the center of the main piston 31 in the direction of the axis J, and is offset by _L1 from the axis J of the main piston 31.

In addition, a rotatable drive shaft 41 is mounted in the hollow part of the main piston 31 in the axial center of the main cylinder 26 at an eccentric position opposite to the clevis pin 40 by a distance L ₂ from the axis J of the main cylinder 26. It passes through W and is inserted into the main cylinder 26.

Reference numerals 42 and 43 shown in FIG. 4 are bearings that support the drive shaft 41, and the clevis pin 40 is slidably slidable in the groove direction at the tip of a yoke 45 fixed to the drive shaft 41 with a key 44. A yoke groove 46 for engagement is formed.

The yoke groove 46 is formed at an angle α with respect to the center line k of the yoke 45 (however, in FIG. 3, the case where α=0 is shown by a solid line).

Lubricating grease or the like is injected into the main piston 31 in advance. Also, the tip 4 of the drive shaft 41
7 is machined into a square shaft shape in order to attach a manual handle, an indicator and other control devices, and the other end 48
A shaft hole 49 is provided in the shaft hole 49 for connection to a shaft of a driven body such as a butterfly valve. 50 and 51
are an oil seal and a retaining ring. Inside the left and right sliding contact parts 34 and 35 of the main piston 31,
Recessed portions 53, 5 for reducing the weight of the piston
3 is formed.

The sub-cylinder 26b, which is coaxial with the main cylinder 26 and has a cylindrical shape, is separably fixed to the right side opening of the main cylinder 26 by bolts or the like. A fluid introduction hole 102 connected to the fluid introduction hole 100 of the main cylinder 26 is arranged in the casing wall of the sub-cylinder 26b in the cylinder axis direction. The lid member 27 functions to partition the cylinder chamber 54 in the sub-cylinder 26b and the cylinder chamber 28 of the main cylinder 26, and has a rod insertion hole 55 coaxial with the shaft center J bored in the center thereof. A piston rod 5 is fixed to a sub-piston 57 which is slidable along the inner cylindrical portion 56 of the sub-cylinder 26b within the rod insertion hole 55.
8 is slidably inserted, and its tip 59 is separate from the main piston 31 so that it comes into contact with the side surface of the sliding contact portion 35 of the main piston 31 when the sub-piston 57 is pushed in the direction of the main piston 31. separated into the body.

Therefore, the cylinder chamber 54 contains the sub-piston 5.
7 into a left cylinder chamber 54a and a right cylinder chamber 54b.

As mentioned above, since the sub cylinder 26b is freely replaceable with respect to the main cylinder 26, it is possible to cope with an increase in the load on the valve only by replacing the relatively inexpensive sub cylinder 26b and sub piston 57. .

The right side opening of the sub-cylinder 26b is closed by a screw case 59, and a sliding cylinder 63 is inserted into the screw case 59 so as to be slidable in the direction of the axis J. A key groove 60 in the axis J direction is carved on the outer periphery, and this key groove 6
The guide screw 61 screwed into the screw case 59 at
Since the columnar head 62 is inserted, rotation around the axis J is prevented.

Further, a female thread 64 is carved on the inner circumference of the sliding cylinder 63, and a threaded rod 6 is screwed into this female thread 64.
5 protrudes rightward from the screw case 59, and a handle 67 is fixed to this tip 66. In this case, the sub-piston 57 and the main piston 31 are mechanically moved by the screw case 59, the guide screw 61, the sliding cylinder 63, the screw rod 65, etc., and the drive shaft 41 is stopped at a predetermined rotational position. A mechanism 103 is configured.

During normal operation, the left end 68 of the threaded rod 6 is recessed into the sliding cylinder 63, and the left end 69 of the sliding cylinder 63 contacts the right side of the sub-piston 57.

A screw case 59, which is an example of a lid member of the sub-cylinder 26b, is provided with a fluid introduction hole 70, which is an example of a nozzle hole that communicates with the fluid introduction hole 32 and the right cylinder chamber 54b of the sub-cylinder 26b.

Note that 71 and 73 are seal members, respectively.

A return coil spring 74 is compressed in the spring case 26a in the direction of the axis J, and the disk 75, which is urged in the direction of the main piston 31 by the coil spring 74, has an axis A stopper shaft 76 coaxial with J is fixed, and the right end 76a of this stopper shaft 76 is connected to the left sliding contact portion 3 of the main piston 31.
It is always in contact with the left side surface 34a of 4, being biased by the coil spring 74.

The adjuster bolt 77 screwed onto the left end of the spring case 26a serves as a hit when the stopper shaft 76 moves to the left by the main piston 31. The forward opening position of the valve is determined by the tightening position of the stop bolt 77.

Next, the operation of the above embodiment according to the present invention will be further explained. In the state shown in the third diagram, the piston 31
has moved to the rightmost side, and therefore the yoke 45
A driven body such as a butterfly valve connected to this via the drive shaft 41 is in a state where it has rotated clockwise to the maximum extent. For example, in the case of a butterfly valve, this state indicates a completely closed state of the valve, and a position where the drive shaft 41 is rotated approximately 90 degrees counterclockwise from this state is a fully open position.

Next, compressed air or the like is supplied from the pressure source 1 shown in FIG. 1 to the right cylinder chamber 28a of the main cylinder 26 through the fluid introduction hole 100 and the fluid introduction hole 32, and the fluid introduction hole connected and communicating therewith. 102,
When compressed air and the like are supplied to the right cylinder chamber 54b of the sub-cylinder 26b through the fluid introduction hole 70 and freely discharged from the fluid introduction hole 33 and the fluid introduction hole 101, the main piston 31 absorbs the compressed air and the like from the cylinder chamber 28a. The coil spring 74 is pushed by the piston rod 58 of the sub-piston 57, which is urged leftward by the pressure increase in the cylinder chamber 54b.
Move to the left against the

Then, the yoke 45 and the drive shaft 41 integrally connected thereto are rotated counterclockwise by being pushed by the clevis pin 40 installed in the main piston 31. The theoretical torque output T acting on the drive shaft 41 at this time is T = Eccentricity (L ₁ + L ₂ ) x Piston propulsive force F x
C F = working fluid pressure P x pressure receiving area S (where C is a coefficient determined by the rotation angle θ), and the pressure receiving area S is the sliding contact area 3 of the piston 31.
It is given by the effective cross-sectional area of 4.35.

In the present invention, the main piston 31 is piston rodless and is also pressed leftward by the sub-piston 57, so the pressure receiving area S
The repulsive force of the coil spring 74 and the load of the driven body such as the valve are superimposed, and even if a large load acts on the whole, the driven body can be driven without difficulty. be able to.

Furthermore, if the supply of compressed air, etc. to the fluid introduction holes 100, 102 and the fluid introduction holes 32, 70 is stopped and these are opened to the atmosphere, the main piston 31 will move to the right due to the repulsive force of the coil spring 74. do.

By supplying and discharging compressed air or the like to and from the cylinder chambers 28a and 54b in this manner, the main piston 31 can be reciprocated and the drive shaft can be given reciprocating rotational motion.

The positioning of the main piston 31 at the leftmost position is determined by the amount by which the adjustment bolt 77 moves in and out. In the case of a butterfly valve, this positioning determines the valve angle at the fully open position.

Furthermore, if the supply of compressed air, etc. to the cylinder chambers 28a, 54b is cut off due to a power outage or the like while the valves are in operation, the main piston 31 is biased to the right by the repulsive force and load of the coil spring 74. This may cause the valve to be fully closed (initial state), which may lead to a serious accident. in this case,
When the handle 67 connected to the screw rod 65 constituting the stop mechanism 103 is rotated by input, the sliding cylinder 63 moves to the left by the carrying action of the screw rod 65, causing the sub-piston 57 to move to the left. This allows the piston rod 58 to push the main piston 31 to the left and forcibly return it to the fully open position (an example of a predetermined position).

[Effect of idea]

As described above, the present invention provides a rotary actuator that converts the linear motion of the main piston that reciprocates while sliding against the inner wall of the main cylinder into the rotational motion of a drive shaft to which a yoke is attached by means of a scutching mechanism. is composed of two sliding contact parts and an intermediate rib that integrally connects the two sliding contact parts with a hollow part in between, and a drive shaft connected to the load side is connected to the hollow part of the main piston. A clevis pin is attached rotatably through the intermediate rib at a position eccentric from the axis of the main cylinder, and a clevis pin is attached at a position on the intermediate rib eccentric from the axis of the main cylinder with respect to the drive shaft, and The clevis pin is slidably engaged in the yoke groove of the yoke fixed to the shaft in the direction of the groove, and the main piston is elastically returned to its initial state on one side in the axial direction of the main cylinder. A coil spring is disposed, and a sub-cylinder separate from the main cylinder is attached to the other side so as to be separable from the main cylinder, and the sub-cylinder is in contact with the main piston to rotate the main piston along its axis. A stop for stopping the drive shaft at a predetermined rotational position by providing a sub-piston that is urged by working fluid from a pressure source in the core direction, and mechanically moving the sub-piston and the main piston in the sub-cylinder. A mechanism is provided in the casing walls of the main cylinder and the sub-cylinder, and the fluid introduction holes for the working fluid are arranged in the cylinder axial direction so as to communicate with each other, and the sub-cylinder and the cover member of the sub-cylinder are further provided with: Since this is a rotary actuator characterized by having a nozzle hole that is connected to the fluid introduction hole at one end and opened to the cylinder chamber at the other end, it is much more efficient than the rotary actuator itself. By installing a low-cost sub-piston in series with the rotary actuator, we were able to increase the valve driving force without increasing the price. In addition, the cylinder of the sub-piston can be separated from the cylinder of the rotary actuator so that the sub-piston can be changed to a larger one according to the valve capacity. Therefore, it has become possible to respond to driven objects such as butterfly valves in which the required driving force changes depending on the size without increasing the cost or the space required.

In addition, when multiple sub-cylinders are connected in series to increase the valve driving force, in this invention, the fluid introduction holes for the working fluid from the pressure source are arranged in the casing wall of the cylinder so that they communicate with each other. As a result, it is no longer necessary to increase external piping procedures according to the number of sub-cylinders added each time the number of connections is increased, and it is easy to increase the valve driving force simply by connecting sub-cylinders. I am now able to aim for this. In addition, the lid member has a nozzle hole connected to the fluid introduction hole, so even if you remove the sub-cylinder and use it as a normal single-cylinder actuator, you can easily complete the piping by simply removing the sub-cylinder. .

Furthermore, if the above-mentioned sub-piston is connected to the piston of the rotary actuator, if the sub-piston's sub-cylinder and the main cylinder on the rotary actuator side are even slightly misaligned, both pistons will not be able to slide. Therefore, it is necessary to increase the machining accuracy more than necessary, but in this invention, the sub-piston is separated from the piston on the rotary actuator side, so there is no need to align the two cylinders with each other. Both pistons can slide extremely lightly.

Furthermore, in the rotary actuator having the above configuration, if the supply of working fluid such as compressed air to the cylinder is cut off due to a power outage or the like while the valve, which is an example of the sliding object, is being operated, the coil spring The main piston is urged toward the initial position by the repulsive force and load, and the valve becomes, for example, fully closed (initial state), which may lead to a serious accident. In this case, for example, when the stop mechanism is operated manually, the drive shaft is rotated via the sub-piston and the main piston, thereby forcibly returning the valve to the fully open position (an example of a predetermined position). This can greatly contribute to improving ease of handling and safety.

[Brief explanation of the drawing]

Fig. 1 is a hydraulic circuit diagram including a sectional view of a conventional rotary actuator, Fig. 2 is a plan view of a rotary actuator that is an embodiment of the present invention, and Fig. 3 is a sectional view of the same side. (The main piston is shown in its most rightward stroke.) Figure 4 shows the 3rd
5 is a perspective view of a main piston that can be used in the same embodiment. Explanation of symbols, 26...Main cylinder, 26b
...Sub cylinder, 27...Lid material, 34, 35...
...Sliding contact portion, 54...Cylinder chamber, 59...Screw case, 61...Screw guide, 103...Stop mechanism, 29...Inner wall, 30...Seal member, 31...
...Main piston, 36, 37...Intermediate rib, 4
0... Clevis pin, 41... Drive shaft, 45...
Yoke, 46... Yoke groove, 57... Sub-piston, 58... Piston rod, 63... Sliding cylinder, 65... Threaded rod, 67... Handle, 7
4...Coil spring, 75...Disc, 76...
...Stotsupa shaft, 100, 101, 102...
...Fluid introduction hole, 32,70...Fluid introduction hole (nozzle hole), J...Cylinder (and piston) axis,
W...Hollow part.

Claims (1)

[Scope of utility model registration request] In a rotary actuator that converts the linear motion of a main piston that reciprocates in sliding contact with the inner wall of the main cylinder into the rotational motion of a drive shaft to which a yoke is attached by a Scotch yoke mechanism, the main piston is connected to two sliding parts and , an intermediate rib that integrally connects both sliding contact parts with an intermediate part in between, and a drive shaft connected to the load side that passes through the hollow part of the main piston to connect the shaft center of the main cylinder. A clevis pin is rotatably mounted on the intermediate rib that is eccentric from the drive shaft across the axis of the main cylinder, and a yoke groove of the yoke fixed to the drive shaft. The clevis pin is slidably engaged in the direction of the groove, and a return coil spring is disposed on one side in the axial direction of the main cylinder to elastically return the main piston to its initial state, On the other side, a sub-cylinder separate from the main cylinder is attached so as to be separable from the main cylinder, and the sub-cylinder is in contact with the main piston so that the main piston is moved in the axial direction from the pressure source. A sub-piston that is energized by a working fluid is provided, and a stop mechanism that mechanically moves the sub-piston and the main piston to stop the drive shaft at a predetermined rotational position is provided in the sub-cylinder, and the main cylinder and a fluid introduction hole for the working fluid is arranged in the casing wall of the sub-cylinder in the cylinder axis direction so as to communicate with each other, and further, one end of each of the sub-cylinder and the lid member of the sub-cylinder is connected to the fluid introduction hole. connected to
A rotary actuator characterized in that the other end is formed with a nozzle hole that opens into a cylinder chamber.