GB2312248A

GB2312248A - Rotary actuator

Info

Publication number: GB2312248A
Application number: GB9607934A
Authority: GB
Inventors: Terry Thomas Cook
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-04-17
Filing date: 1996-04-17
Publication date: 1997-10-22
Also published as: GB9607934D0

Abstract

A rotary actuator uses a double acting piston assembly (20, Fig 1) moving in a toroidal pressure chamber to provide angular motion. A torque is developed by coupling an internal flange plate 13 to the piston. The flange plate is then used to drive a shaft 15 through a ratchet type of clutch 14. The actuator operates in various modes from fluid pressure signals. These modes may be oscillatory, continuous angular motion or step input positional. The design also allows reverse mode operation to give pressure signals out from shaft angular motion. Two actuators may be coupled to a common shaft to provide greater torque than from one actuator. A system may include two actuators connected so that torque is transformed to pressure at one location and the pressure is transformed to torque at another location.

Description

ROTARY ACTUATOR This invention relates to a hydraulic or pneumatic activated device capable of transforming pressure signals into angular motion.

There are many devices known to those skilled in the manufacture of rotary actuators or motors which work on well known principles such as gear motors or swash plate motors. In general, fluid under pressure is introduced via an inlet port to some form of rotational component. After the pressurized fluid has caused rotation, an exhaust port allows venting of the spent fluid to take place and eventual return to some form of reservoir for subsequent re-use.

According to the present invention there is provided an annulus with thickness which contains a hollow toroidal shaped chamber which in turn contains a shaped movable piston coupled to a circular flange plate. The flange plate is concentric with the toroidal chamber and is inserted into the chamber via the internal diameter of the annulus. Seals are provided concentrically on each face of the flange plate to maintain the pressure integrity of the chamber. The centre of the flange plate is fitted with a clutch mechanism which can impart torque to a shaft mounted on bearings. The chamber has a fixed bulkhead in one position across the cross section of the chamber effectively creating changeable volumes on each side of the piston. Thus if the piston travels through the chamber, one volume increases directly as the other decreases.

In one operational mode fluid pressure may be introduced in an oscillatory manner on either side of the piston, However, the pressure oscillations will result in the shaft torque acting in one direction only, as dictated by the clutch mechanism.

Another possible operational mode is to drive the shaft direct and without the clutch.

In this mode the shaft can be made to oscillate clockwise and anticlockwise in sympathy with the pressure signals.

A third mode obtains if a pressure differential should be introduced for a short period on one side of the double acting piston and then held constant on both sides of the piston. The device then becomes a rotary positional transducer working between fine limits.

The flexibility in operation of the device allows many applications in positional control, vibratory systems and rotary drives. If the application area should be as a prime mover in transport systems it is also possible to couple more than one device to an output shaft to increase the torque output.

It is also possible to couple two devices via hydraulic pressure lines whereby rotary movement on the drive shaft of one device will produce corresponding motion on the shaft of the other device. If used in this manner the piston sizes or the toroidal chamber diameters between the devices may be altered to trade-off power for rotation angle or vice-versa.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Fig. 1 Shows a front elevation of the device which is also a sectional view of fig.2 on B-B.

Fig.2 Represents a cross sectional elevation of fig. 1 on A-A Fig.3 Gives a three dimensional view of the flange plate and piston assembly.

Refering to the drawing Fig.2 it may be seen that the enclosure 10 forms a location for all other components which are retained by a circlip 18 and a pressure washer 17. A front plate 11 is in contact with the annulus components 12 and also provides a location for one of a pair of bearings 16. A drive means takes the form of a flange plate 13 which has a piston 20 located on its periphery and a clutch 14 at its centre.

The clutch has a ratchet type action and will only drive the shaft 15 in one rotary direction. If the flange plate is fixed permanently to the output shaft the device then becomes a positional device or an oscillatory output device.

It may be seen that sealing means are provided about the toroidal chamber and are fitted in groved sections within the annulus components 12. The smaller diameter seals 21 are in sliding contact with the flange plate whilst the larger diameter seal 22 is stationary Fig. 1 shows a cross section on B-B of fig.2.

The means for allowing hydraulic pressure into the toroidal piston chamber are shown as two tapped input/output ports 19 situated on either side of the bulkhead 23. Thus if pressure is increasing on one side of the piston 20 motion is allowed and the flange plate is driven by an engagement dog 24 on its periphery, as shown in fig.3.

With reference to fig. 2 it may be seen that the circular containment wall of the enclosure 10 could be extended to allow more annulus sections 12 and corresponding drive sections to be fitted. In this enhanced embodiment the retention means of circlip and pressure washer would still be required and the drive shaft 15 would be correspondingly longer.

Claims

CLAIIWS

1. A rotary actuator which operates by means of a shaped piston which is profiled to travel within a toroidal shaped pressure chamber.

2. A rotary actuator, as claimed in claim 1, which has a drive means which uses a circular flange plate, free to rotate between the walls of a two piece fabricated annulus, on which is located a drive dog coupled to a shaped piston running in a toroidal pressure chamber.

3. A rotary actuator, as claimed in claim 1 or claim 2, which has the means to provide positional, oscillatory or rotary displacements to an output shaft.

4. A rotary actuator, as claimed in claims 1,2 or 3 which has the ability to operate in the reverse mode whereby shaft input motion is translated to corresponding hydraulic or pneumatic output signals.

5. A rotary actuator, as claimed in claims 1 to 4, which may be coupled to a common shaft with other similar actuators to produce a greater shaft torque.

6. A rotary actuator, as claimed in any preceeding claim, that may be used back-to back in a system with a similar actuator to transform torque to a pressure signal and then transform the resulting pressure signal to torque in another location.

7. A rotary actuator, substantially as described in the preceeding claims and in the figures 1 to 3 inclusive, which may be used with a similar actuator in a system to translate shaft torque to a greater or lesser magnitude.