GB2030652A - Rotary Positive-displacement Fluid-machines - Google Patents

Abstract

An oscillating compressed-air motor includes a shaft 1 carrying a pair of radial vanes on which the air acts to partially rotate the shaft. The vanes are located in a cylinder 2 which is furnished with fixed partitions 5. At the end of each shaft movement an air-operated brake stops the shaft. The brake includes an inflatable rubber sleeve 4 acting on the inner surface of a cup-shaped member 3 secured to the shaft. The motor may drive a windscreen wiper. <IMAGE>

Description

SPECIFICATION Reciprocating Rotary Motor This invention relates to reciprocating rotary motors operated by pressure fluid, preferably air.

In particular the invention may find application in driving windscreen wipers.

Prior motors have been proposed in which two vanes are mounted symmetrically on a shaft and air acts on the vanes to drive the shaft. After a predetermined angular movement of the shaft movement is stopped and reversed, as desired.

It is an object of the invention to provide a rotary motor in which motion is positively arrested and held at the desired position and loss of operating fluid is reduced.

According to the invention a reciprocating rotary motor comprises a cylinder, a shaft extending through the cylinder and having radial vanes, the cylinder being closed at its ends, a brake member secured to the shaft and providing a brake surface, a flexible fixed brake element engageable with the brake surface, under the influence of drive fluid to brake the shaft, radial partitions forming chambers in which the vanes are angularly movable, a distributor valve for controlling the flow of drive fluid to the chambers and to the brake element, and stops for controlling the distributor valve and operating the brake element.

Further features of the invention appear from the following description of an embodiment of the invention given by way of example only and with reference to the drawings, in which: Fig. I is a longitudinal section through an air motor, Fig. II is an external elevation of the motor of Fig. I, Fig. III is a cross-section through an upper part of the motor of Fig. I, Fig. IV is a cross-section through a lower part of the motor of Fig. I, Fig. V shows sections through three possible forms of brake ring for the motor of the previous figures, and Fig. VI is a diagrammatic cross-section of a distributor valve.

Referring to the drawings, air under pressure for operating the motor is fed to one or other of two connectors 13, depending on the direction of rotation, and the air will in practice be directed alternately to the connectors. The air passes from the relevant connector 13 to an inlet port of a distributor valve 8 and through the valve to a conduit 1 7 formed in a radial partition 5. The conduit 17 leads the air into a chamber formed in a cylinder 2 of the motor and a conduit 1 9 formed in a shaft 1 leads air from said chamber into the other operative chamber in the cylinder 2.

The air in said chambers pushes on vanes carried by the shaft 1 and turns the shaft about a predetermined angle, air in the chambers on the opposite sides of the vanes being discharged through corresponding conduits to those at 1 7 formed in the partition 5 and through the valve 8.

The cylinder 2 has upper and lower closure members 6 secured by screws 12 and two radial partitions 5 divide the interior of the cylinder into two substantially semi-cylindrical chambers in which the vanes move.

At the upper end of the shaft 1 is fixed a cupshaped member 3 which rotates with the shaft 1 and acts as a brake surface over its inner cylindrical portion. Within the brake surface is mounted a fixed rubber element 4 forming an air chamber communicating with a conduit 18 which is connected to the valve 8. As the shaft 1 turns the member 3 also turns relative to the element 4 until the valve 8 is moved to introduce air along the conduit 1 8 by engagement of a stop 9 with the valve 8. This also interrupts the supply of air to the conduit 17. The air acting on the element 4 causes it to expand and to engage the brake surface on the member 3 to thereby positively brake the movement of the shaft 1.

Two steps are provided for acting in each direction of rotation and the positions of the stops can be adjusted by means of screws 10 to adjust the angular movement of the shaft.

The vanes are sealed against the cylinder by Teflon strips 1 6 pressed by resilient strips 1 5.

Brackets 7 serve to locate the motor and are connected by screws 11 to the partitions 5.

Where the shaft 1 passes through the closure member 6 there are bushings 14 and the ends of the shaft are of square cross-section for fitting to the item to be driven. The resilient element 4 can take various forms, as illustrated in Fig. V.

It will be appreciated that the motor provides positive braking at the end of each desired movement and, due to the lack of pressure in the chambers containing moving parts, loss of operating air due to inadequate sealing is eliminated when the shaft is stationary.

This invention is an improvement of the device disclosed in Yugoslavian patent application P3019/74.

Claims

1. A reciprocating rotary motor comprising a cylinder, a shaft extending through the cylinder and having radial vanes, the cylinder being closed at its ends, a brake member secured to the shaft and providing a brake surface, a flexible fixed brake element engageable with the brake surface under the influence of drive fluid to brake the shaft, radial partitions forming chambers in which the vanes are angularly moveable, a distributor valve for controlling the flow of drive fluid to the chambers and to the brake element, and stops for controlling the distributor valve and operating the brake element.

2. A motor according to claim 1 comprising brackets connected to the partitions.

3. A reciprocating rotary motor substantially as described with reference to the drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Reciprocating Rotary Motor This invention relates to reciprocating rotary motors operated by pressure fluid, preferably air. In particular the invention may find application in driving windscreen wipers. Prior motors have been proposed in which two vanes are mounted symmetrically on a shaft and air acts on the vanes to drive the shaft. After a predetermined angular movement of the shaft movement is stopped and reversed, as desired. It is an object of the invention to provide a rotary motor in which motion is positively arrested and held at the desired position and loss of operating fluid is reduced. According to the invention a reciprocating rotary motor comprises a cylinder, a shaft extending through the cylinder and having radial vanes, the cylinder being closed at its ends, a brake member secured to the shaft and providing a brake surface, a flexible fixed brake element engageable with the brake surface, under the influence of drive fluid to brake the shaft, radial partitions forming chambers in which the vanes are angularly movable, a distributor valve for controlling the flow of drive fluid to the chambers and to the brake element, and stops for controlling the distributor valve and operating the brake element. Further features of the invention appear from the following description of an embodiment of the invention given by way of example only and with reference to the drawings, in which: Fig. I is a longitudinal section through an air motor, Fig. II is an external elevation of the motor of Fig. I, Fig. III is a cross-section through an upper part of the motor of Fig. I, Fig. IV is a cross-section through a lower part of the motor of Fig. I, Fig. V shows sections through three possible forms of brake ring for the motor of the previous figures, and Fig. VI is a diagrammatic cross-section of a distributor valve. Referring to the drawings, air under pressure for operating the motor is fed to one or other of two connectors 13, depending on the direction of rotation, and the air will in practice be directed alternately to the connectors. The air passes from the relevant connector 13 to an inlet port of a distributor valve 8 and through the valve to a conduit 1 7 formed in a radial partition 5. The conduit 17 leads the air into a chamber formed in a cylinder 2 of the motor and a conduit 1 9 formed in a shaft 1 leads air from said chamber into the other operative chamber in the cylinder 2. The air in said chambers pushes on vanes carried by the shaft 1 and turns the shaft about a predetermined angle, air in the chambers on the opposite sides of the vanes being discharged through corresponding conduits to those at 1 7 formed in the partition 5 and through the valve 8. The cylinder 2 has upper and lower closure members 6 secured by screws 12 and two radial partitions 5 divide the interior of the cylinder into two substantially semi-cylindrical chambers in which the vanes move. At the upper end of the shaft 1 is fixed a cupshaped member 3 which rotates with the shaft 1 and acts as a brake surface over its inner cylindrical portion. Within the brake surface is mounted a fixed rubber element 4 forming an air chamber communicating with a conduit 18 which is connected to the valve 8. As the shaft 1 turns the member 3 also turns relative to the element 4 until the valve 8 is moved to introduce air along the conduit 1 8 by engagement of a stop 9 with the valve 8. This also interrupts the supply of air to the conduit 17. The air acting on the element 4 causes it to expand and to engage the brake surface on the member 3 to thereby positively brake the movement of the shaft 1. Two steps are provided for acting in each direction of rotation and the positions of the stops can be adjusted by means of screws 10 to adjust the angular movement of the shaft. The vanes are sealed against the cylinder by Teflon strips 1 6 pressed by resilient strips 1 5. Brackets 7 serve to locate the motor and are connected by screws 11 to the partitions 5. Where the shaft 1 passes through the closure member 6 there are bushings 14 and the ends of the shaft are of square cross-section for fitting to the item to be driven. The resilient element 4 can take various forms, as illustrated in Fig. V. It will be appreciated that the motor provides positive braking at the end of each desired movement and, due to the lack of pressure in the chambers containing moving parts, loss of operating air due to inadequate sealing is eliminated when the shaft is stationary. This invention is an improvement of the device disclosed in Yugoslavian patent application P3019/74. Claims

1. A reciprocating rotary motor comprising a cylinder, a shaft extending through the cylinder and having radial vanes, the cylinder being closed at its ends, a brake member secured to the shaft and providing a brake surface, a flexible fixed brake element engageable with the brake surface under the influence of drive fluid to brake the shaft, radial partitions forming chambers in which the vanes are angularly moveable, a distributor valve for controlling the flow of drive fluid to the chambers and to the brake element, and stops for controlling the distributor valve and operating the brake element.

2. A motor according to claim 1 comprising brackets connected to the partitions.

3. A reciprocating rotary motor substantially as described with reference to the drawings.