JPH0369003B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to actuators used to convert fluid pressure into mechanical motion. Furthermore, the invention relates to such an actuator which produces a rotational movement by means of an annular piston.

(Conventional technology) Rotary actuators are used to open and close doors and windows.
Used in raising and lowering aircraft wing flaps, rotary switches or operating valves and other devices. Such actuators are generally fluid-driven, and the fluid, typically hydraulic or pneumatic, is used to effect the rotational movement.

One mechanism used to obtain this rotational motion uses one or more annular pistons. For example, U.S. Pat.
No. 163186 discloses a pair of opposed annular pistons,
A vibration engine for use in generating motion is disclosed. A similar device that uses a dual annular piston for vibration is disclosed in U.S. Pat. No. 3,446,120, issued November 14, 1966.

Means other than annular piston devices have been used in the past to create this rotational motion. A linear piston mechanism was used in which a linearly moving piston moved a rack gear across the gear shaft, imparting rotational motion to the gear shaft. However, annular piston devices produce greater torque and are more compact and lightweight.

The actuator can be single-acting or double-acting. Single-acting actuators provide movement in only one direction. For example, in a single-acting piston mechanism, the piston is moved by pressurized fluid into the chamber. Once the pressure is released, the piston is returned to its initial position, for example by a spring.

Double-acting actuators produce rotational motion in both clockwise and counterclockwise directions. This is shown, for example, in U.S. Pat. No. 3,446,120,
A piston moving within the opposing piston chamber is caused to move in a direction opposite to the oscillating pressure on the opposing chamber.

Prior art rotary actuators have a number of drawbacks. The first drawback is that it is difficult to form a sufficient double seal between the piston head and the annular chamber. Because of the dimensional tolerances of the annular chamber that occur during manufacturing, it has been decided to design a piston head that forms a sufficient double seal against the walls of the annular chamber without creating friction between the piston head and the walls of the annular chamber. Difficulties arose. Depending on the supplied room pressure,
The ultimate goal is to produce maximum torque from the rotary actuator. It is easy to see that excess friction between the piston head and the wall of the annular chamber will greatly reduce the resultant torque.

Another disadvantage caused by the annular piston arrangement is that the annular piston arm is subject to some bending when the direction of the force exerted on the piston arm by the fluid pressure against the piston head is linear and tangential to the axis of the piston arm. It happened. Slight bending of the piston arm increases friction between the piston head and the walls of the annular chamber, reducing actuator performance.

1 was utilized to attempt to counteract this increased friction resulting from the deformation of the chamber wall and piston arm.
One method is to have the piston head floating relative to the piston arm. This means that
For example, Sneen U.S. Pat.
No. 3,446,120 (see FIG. 11) and US Pat. No. 2,649,077 to Mehm (see FIG. 2). Although this method helps reduce friction, there is still significant friction in this device due to the friction of the piston head against the piston arm. In other words, when the piston head is under sufficient pressure, the piston head is forced toward the piston arm under such great pressure. Therefore, a large amount of friction exists between the piston head and the piston arm, and the piston head tends to move laterally relative to the piston arm. Therefore, the fact that the piston head is designed to be floating in prior art devices means that the friction between the piston head and the piston arm tends to hold the piston head with great force relative to room temperature, so that the piston head and the walls of the chamber as well as deteriorating actuator performance.

Another method used to reduce sidewall friction has been the provision of sliding pads of wear-resistant material on the outer side of the piston arm that contacts the chamber wall. May 1969
See U.S. Pat. No. 3,444,788 to Sneen, issued on the 20th. This method also does not solve the problem of piston head/piston arm friction.

Another drawback inherent in prior art devices is their complex design and component parts that are expensive to manufacture and maintain.

SUMMARY OF THE INVENTION The present invention utilizes a single annular chamber integrally formed in the housing and a piston head that operates within the single annular chamber to improve performance. The problem to be solved is to overcome the drawbacks of the prior art with an actuator having a friction reducing means between it and the arm.

SUMMARY OF THE INVENTION A novel design for the actuator forms a single annular chamber integrally formed within a cylindrical cavity in the housing. A single piston head mounted on a single arm is moved in both directions by applying pressure to the large cavity in which the piston arm resides within the annular chamber, and the pressure acting on the underside of the piston head forces the piston into the annular chamber. It is possible to form a conventional pressurizing means for pressurizing the annular chamber forward of the piston head in order to drive and apply a force to the piston arm outside the annular chamber, where it is very simple and inexpensive. Most of the embodiments are made to create the vibrational or rotational motion required for the actuator used.

Furthermore, friction reducing means are provided between the piston head and the piston arm, allowing free movement of the piston head with respect to the piston arm, so that the piston head can float in the annular chamber, where the piston head can absorb the load. absorbing any bending of the piston arm under
Allows for any variation in the dimensions of the annular chamber.

The invention provides that the piston head is movable axially relative to the piston arm between a first and second position or within a limited range, and that the friction reducing device is arranged during lateral movement of the piston head. To provide a rotary actuator having a feature of contacting an annular interior wall in both positions to reduce friction.

(Example) An actuator according to an example of the present invention has an outer housing 10. As shown in FIG. In the preferred embodiment, the housing 10 is circular in profile for greater compactness. The housing 10 is made of steel. The inside of the housing 10 has a hollow cylindrical shape and includes a first chamber 12 and a second chamber 14 .
The second chamber 14 is annular in profile, and in the preferred embodiment is in the shape of a toroidal arc segment. In order to obtain a high degree of precision and thus reduce dimensional tolerances of the second chamber 14, the toroidal segments are preferably machined rather than cast.

The housing 10 has a small hole at one end through which a drive shaft is inserted. housing 10
The other end is open. A diaphragm 18 having a central hole that fits the end of the drive shaft 16 fits into the housing 10 so as to surround the first chamber 12 .

Housing 10 is generally a cylindrical body with one end closed and the other end open. A second annular chamber 14 is formed at the bottom edge of the closed end of this cylinder. The remaining volume of the cylinder is opened to form an empty space. This large empty space is the diaphragm 18
After being installed, the first chamber 12 forms a significant advantage for the structure of the actuator.

For example, this configuration may be preferred between the piston arm 40 and the drive shaft 16 rather than the spline connection commonly utilized between the piston and the drive shaft in other actuators.
allows them to be integrated.

Thrust bearings 20 and 22 are fitted around drive shaft 16 and into housing 10 and diaphragm 18 holes. Two sets of packing and retainer rings 24 and 26 seal the thrust bearing 20 between the housing 10 and the drive shaft 16, and two sets of packing and retainer rings 28 and 30 seal the thrust bearing 22, the diaphragm 18, and the drive shaft. 16 to form a similar function as described above. Another packing and retainer ring set 32 provides a seal between the outer circumferential surface of diaphragm 18 and housing 10. Metal split ring 34 is inserted into a suitably sized opening formed by corresponding grooves in housing 10 and diaphragm 18 to hold diaphragm 18 in place relative to housing 10. Connection hole 3
6 is formed on the outer surface of the housing 10 to guide the split ring 34 into a predetermined position. A locking screw 38 holds the diaphragm 18 in place relative to the housing 10 against rotation.

In FIG. 1, piston arm 40 is integrally formed with drive shaft 6 so as to be a unitary structure. Naturally, conventional coupling means can be used. First chamber 12 is also of sufficient size to accommodate piston arm 40 and a portion of drive shaft 16 therein.

A rubber stopper 42 is attached to the heel portion of the piston arm 40. The shoulder portion 44 is the housing 1
0, and a rubber stopper 42 is provided on the shoulder.
contact and stop the movement of the piston arm 40.

The piston arm 40 is or is formed as an arcuate segment of a toroid with a circular arc of the same radius as the radius of the second chamber.

The cross-sectional diameter of the piston arm 40 is the same as that of the second chamber 14.
, the piston arm 40 is free to move freely into the second chamber 14 . In order for the piston arm 40 to be able to move completely into the second chamber 14, the center point of the arc radius of the piston arm 40 must be the same as the center point of the arc radius of the second chamber 14. is clear. Furthermore, to improve compactness, the distal end 46 of the piston arm 40 is at or near the entrance to the second chamber 14 when the piston arm 40 is fully retracted and the rubber stop 42 is in a position where it impinges on the shoulder 44. It is in.

Supply ports 48 and 50 provide fluid pressure between the first chamber 12 and the second chamber.
It forms means that can be introduced into each of the chambers 14. Threaded holes 52, 53, 54, 55 are formed on the exterior of casing 10 to facilitate attachment of the actuator to other surfaces.

The piston head 58 is mounted to the piston arm 40 by means which permit the piston head to float laterally, or in the preferred embodiment, radially relative to the piston arm 40.
These attachment means include a corner notch 60 formed in the piston arm 40, which corner notch 60 defines a shoulder 62 parallel to a surface 64 of the piston arm 40. 1 between the surface 64 and the shoulder 62
Two holes are formed. The hole is located at the center point of surface 64. A bolt 66 with an enlarged head 68 extends through the hole and is fastened to the shoulder 62 by a nut 70. The length of bolt 66 is such that it extends a significant distance beyond face 64 of piston arm 40. bolt 66
The enlarged head 68 of forms a shoulder 72 parallel to the plane 64.

Piston head 58, preferably constructed of an aluminum-nickel-bronze alloy, is cup-shaped with an internal cavity 74 of sufficient size to receive enlarged head 68 of bolt 66.
A portion of the interior surface of the cavity 74 is threaded to receive a threaded insert 76 that retains the piston head 58 over the enlarged head 68 of the bolt 66. The hole between the shoulder 62 and the surface 64 of the piston arm 40 allows the bolt 6 to
Preferably, the bolt 66 has an inner diameter equal to the outer diameter of the bolt 66 so that it does not move laterally or radially relative to its hole. On the other hand, the inner diameter of the hole 78 in the threaded insert 76 is significantly larger than the outer diameter of the bolt 66. Similarly, the inner diameter of cavity 74 is significantly larger than the outer diameter of head 68. Therefore, the piston head 5
8 can move laterally or radially relative to the bolt 66 and thus relative to the piston arm 40. Furthermore, it is clear that some free space must be created between the piston head 58 and the piston arm 40 to accommodate this lateral or radial movement. This free space allows the internal cavity 74 and the piston head 58 to be connected to the bolt 6 which extends away from the face 64 of the piston arm 40.
This can be obtained by making it considerably deeper than the length of 6. A locking pin 65 is inserted into the associated holes in piston head 58 and insert 76 to prevent insert 76 from rotating after insertion. A screwdriver hole 67 is additionally formed in the insert 76 to facilitate insertion and removal.

Despite these provisions being made to allow radial or lateral movement of the piston head 58 relative to the piston arm 40, the second chamber 14
When exposed to high pressure, a large force is exerted on the piston head 58 such that it pushes the piston head 58 toward the surface 64 of the piston arm 40. The resultant friction between the piston head 58 and the insert 76 toward the face 64 of the piston arm 40 substantially eliminates free lateral movement of the piston head 58. This completely negates the advantageous results expected by allowing the piston 58 to float in the first case. To prevent this phenomenon, a low friction thrust washer 80 is placed between the shoulder 72 of the enlarged head 68 and the threaded insert 76, and another low friction thrust washer 82 is placed between the face 64 of the piston arm 40 and the threaded insert 76. It is placed between.

That is, as described above, the insert 7 of the piston 58
6 and the shoulder 72 of the enlarged head 68 (when the chamber 12 is under pressure), a low friction thrust washer 80 is attached to the shoulder 72 so that the combined frictional force between the shoulder 72 (when the chamber 12 is under pressure) does not interfere with free lateral movement. It is arranged between the insert body 76 and the insert body 76 . Therefore, the piston 58 can be moved between a first position (see FIG. 1: washers 80 create low friction for lateral movement) and a second position (washers 80 create low friction for lateral movement).
2) creates low friction for lateral movement) relative to the arm 40 in the axial direction of the bolt 66.

The thrust washer has a coating of a polytetrafluoroethylene-lead blend with a very low coefficient of friction. Therefore, even under a sufficient load, the piston head 58 is in a floating state with respect to the piston arm 40. Thus, while the piston arm 40 moves over its arc within the second chamber 14, the piston arm 40 can bend during pressure fluctuations, or the piston head 58 can bend against the wall of the second chamber 14. Piston head 58 to accommodate contour variations.
Piston arm 40 more easily and with lower friction
Since the piston head 5 is in a floating state relative to
8 adjusts its position in search of a path of least resistance so that friction between the piston head and the wall of the second chamber is minimized, producing maximum performance of the actuator.

FIG. 1 shows one of several embodiments of a piston head 58 profile. Here, the external contour of the piston head 58 is formed in such a way that the piston head 58 touches the wall of the second chamber 14 at only one point on its periphery. At the point of contact, a sealing ring 84 is fitted into a suitably dimensioned groove formed in the piston head 58.

Another method of attaching piston head 58 to piston arm 40 is shown in FIGS. 5 and 6. Here the piston arms 58' and 58'' do not have an internal cavity; rather, the piston head has a centrally located hole into which the bolt 66 is inserted. Another modification is made in the face 64 of the piston arm 40. The ends of piston arm 40 are reduced in size to create a shoulder 100 and neck 102. Piston heads 58' and 58'' have small cavities into which neck 102 fits. To form the piston heads 58' and 58'' to move relative to the piston arm in this arrangement, the surfaces 64 and shoulders 6
A hole 104 is formed between the holes 104 and 2 with dimensions significantly larger than the dimensions of the bolts 66. A spacer 106 extends between the nut 70 and the underside of the piston heads 58' and 58'' to enable pretensioning of the bolt 66. This pretensioning of the bolt 66 increases fatigue life and also This allows for precise play between the heads 58' and 58'' and the piston arm 40. In this embodiment, thrust washers 80 and 82
are located between the piston heads 58' and 58'' and the face 64 and between the shoulder 62 and the nut 70. A seal and retainer 108 must be used since the piston head bore is under pressure. is understood.

Figures 5 and 6 also show other possible embodiments of the piston head profile. Turning first to FIG. 5, the toroidal segment shape of the piston head 58' increases the sealing contact between the piston head 58' and the wall of the second chamber 14; this configuration is subject to very high pressures. It is most effective for the part where it is used.
Although the piston head 58' in this state may cause a large amount of friction between the piston head and the wall of the second chamber 14, the toroidal shape of the second chamber 14 is precisely machined and the movement of the piston arm 40 is prevented. This creates a low-friction floating condition for the piston head 58' in the piston head 58' to reduce increased friction problems.

In FIG. 6, another example piston head 58'' is shown, in which the piston outer surface is made to have the same radius as the inner surface 110 of the outer wall of the second chamber 14.

Although specific embodiments of the inventive concept have been described in the drawings, many variations can be made by those skilled in the art without departing from the inventive concept as set forth in the claims. be. The scope of protection of the invention is therefore not limited to a few specific embodiments.

(Effects) As is clear from the above, the invention can provide a rotary actuator with a simple structure and improved performance characteristics.

[Brief explanation of drawings]

FIG. 1 is a top view of the actuator of the present invention,
FIG. 2 is a cross-sectional view taken along the line -- in FIG. 2, showing the large chamber in the cylindrical housing containing the annular chamber and the single piston and piston arm operating within the annular chamber, and also showing the piston head and piston arm; Friction reducing means are shown between the piston arms;
FIG. 2 is a side view of the actuator of the present invention, a sectional view taken along the line - of FIG. 1, showing the relationship between the central drive shaft, the annular piston, and the annular chamber;
The general structure of the actuator is also shown,
3 is a bottom view of the actuator, FIG. 4 is a top view of the actuator, and FIG. 5 is an isolation of an alternative embodiment of the piston head of the actuator and an alternative embodiment of the manner in which the piston head is attached to the piston arm. FIG. 6 is an isolated view of an alternative embodiment of the piston head. 10... Housing, 12... First chamber, 14...
...Second chamber (annular chamber), 16...Drive shaft, 18...
Diaphragm, 40...Piston arm, 58...
...Piston head.

Claims (1)

Claims: 1. A housing having a first closed end and an open second end, and an annular arc segment of a toroid within the housing as the housing faces the closed first end. a cylindrical hollow space except for a chamber, the annular chamber opening into the hollow space in the housing, a hole formed in the center of the closed first end of the housing, and a rotatable hole in the housing; a drive shaft removably mounted and extending out of the housing through a hole in the closed first end; an annular piston arm secured to the drive shaft; an end of the piston arm pivoting within the annular chamber; a piston head fixed to the piston arm so as to be in airtight contact with the annular chamber during rotation of the piston arm;
a cap device closing the end; a supply port for introducing fluid pressure into the annular chamber and into the hollow space in the housing; the piston head moving in either direction within the annular chamber;
a fixing device for attaching said piston head to said piston arm; and a first position when said piston head moves laterally relative to said piston arm and said piston head provides fluid pressure to said hollow space. and a second position upon supplying fluid pressure into the annular chamber, the locking device also moves in the axial direction of the locking device, and so as to reduce friction when the piston head moves relative to the piston arm. and a friction reduction device arranged to engage in both the first and second positions. 2. The rotary actuator of claim 1, wherein a friction reducing device is disposed between said piston head and said piston arm and between said piston arm and said locking device.