US3399747A

US3399747A - Hydrodynamic fluid brake

Info

Publication number: US3399747A
Application number: US552234A
Authority: US
Inventors: William G Westwell; Roger H Slee
Original assignee: Perkins Engines Ltd
Current assignee: Perkins Ltd
Priority date: 1965-05-26
Filing date: 1966-05-23
Publication date: 1968-09-03
Anticipated expiration: 1985-09-03
Also published as: GB1138622A; DE1600024A1

Description

P 3, 1963 w. G. WESTWELL ETAL 3,399,747

HYDRODYNAMIC FLUID BRAKE 2 Sheets-Sheet 1 Filed May 23, 1966 I nvenlors W/ZZ/AM 6. WFSTWHL R0651? H. 6155 d New & 921M Attorneys P 1968 w. G. WESTWELL ETAL 3,399,747

HYDRODYNAM I C FLUID BRAKE 2 Sheets-Sheet 2 Filed May 23, 1966 I nvenlora m m wm m QWM W5 s United States Patent 3,399,747 HYDRODYNAMIC FLUID BRAKE William G. Westwell, Peterborough, and Roger H. Slee, Surrey, England, assignors to Perkins Engines Limited, London, England Filed May 23, 1966, Ser. No. 552,234 Claims priority, application Great Britain, May 26, 1965, 22,283/ 65 2 Claims. (Cl. 18890) ABSTRACT OF THE DISCLOSURE A hydrodynamic fluid brake including a casing housing a rotor and stator. A plurality of shutter members are located between the rotor and stator. When the casing is empty of hydraulic fluid, the shutters may be closed to interrupt the flow of air between the rotor and stator. For braking, the shutters are opened and hydraulic fluid is introduced into the casing. The interaction of the fluid between the rotor and stator provides a braking effect.

This invention relates to fluid machines of the type having a rotor and a stator and which, when the machine has fluid therein, can provide a braking effect by interaction of the fluid between the rotor and stator.

One example of a fluid machine of this type is a hydrodynamic fluid brake in which the braking action is obtained by filling the casing of a rotor and stator with hydraulic fluid which circulates in a vortex between blading or pockets on the rotor and stator. However, it is a disadvantage that when the hydraulic fluid is removed from the casing, air contained in the casing gives rise to appreciable windage losses.

It is an object of the present invention to provide means for reducing the windage losses of fluid machines of this type.

In accordance with the present invention, a plurality of shutter members are located between the rotor and stator. When the casing is empty of hydraulic fluid, the shutters may be closed to interrupt the flow of air between the rotor and stator. For braking, the shutters are opened and hydraulic fluid is introduced into the casing. The interaction of the fluid between the rotor and stator provides a braking effect.

Preferably, the shutters are mounted on a stationary part of the machine having control means for Opening and closing the shutters.

The control means may include spring means for effecting movement of the shutter members to the closed position, and a hydraulic control system for effecting movement of the shutter members to the open position.

The shutter members may be pivotally mounted at one end on the machine, and may overlap and together form a variable aperture device or iris.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a fragmentary exploded perspective of the rotor and stator of one embodiment of a fluid machine according to the present invention;

FIGS. 2A and 2B are front views of the stator corresponding to FIG. 1 to a reduced scale and showing the shutter members respectively in their closed and open positions; and

FIG. 3 is a view corresponding to FIG. 1 of a rotor and showing another embodiment of the invention.

Referring to FIG. 1, reference numeral designates a rotor having a plurality of rotor pockets 11B disposed on a pitch circle. Rot-or 10 is rotatably contained in one part 12B of a split casing of which the other part is indicated at 12A and forms the stator of the machine. The

3,399,747 Patented Sept. 3, 1968 casing part 12B has an annular land 13 from which project a plurality of studs 14 which engage in a correspond ing plurality of holes 14A in a corresponding land 13A on the part 12A for fastening the casing parts together. The stator has a plurality of pockets 11A which are axially opposite the rotor pockets 11B when the

parts

12A, 12B are assembled. By virtue of the lands 13, 13A there exists a small axial space between the rotor pockets 11B and stator pockets 11A.

Located in the space between pockets 11A- and 11B provided by lands 13, 13A is means for interrupting flow of fluid between the rotor pockets 11B and the stator pockets 11A. In the illustrated embodiment, this means consists of a plurality of shutter members 16 pivotally mounted on the casing part 12B on a pitch circle beyond the outer diameter of the rotor 10. The shutter members 16 are thin metal blades of generally arcuate shape and overlap so as to form a variable aperture device or iris. Each member 16 has an axial pin 17. In order to pivot the shutter members 16, a rotatably adjustable ring 18 is provided which has slots 19 in which the pins 17 are located. Each slot 19 is generally radially directed so that, when the ring 18 is adjusted, the shutter members 16 are induced to pivot on the stationary casing 12A. The shutter members 16 are movable between an open position allowing hydraulic fluid flow between the rotor and stator, and a closed position in which the members 16 interrupt air flow between the rotor and stator. FIGS. 2A and 2B show the shutter members 16 respectively in their closed and open positions.

Control of rotation of ring 18 is provided by a gear segment 20 attached to the ring 18, an axially slideable rack 21 housed in the machine and meshing with the segment 20, and control means, which may be hydraulic, pneumatic, or mechanical for example, controlling axial movement of the rack 21.

Rack 21 is loaded by a compression spring 21A on an extension rod 213 of the rack 21 and has a control rod 21C. Extension rod 213 is connected by a coupling 21D to a hydraulic fluid control valve 22 through which fluid may flow to fill the machine. When the rack 21 is moved in one direction, the direction of the arrow in FIG. 1, the supply of hydraulic fluid to the machine is increased, whereas movement of the rack 21 in the opposite direction causes less hydraulic fluid to be supplied to the machine, or the supply to be cut off.

Movement of the rack 21 in the direction of the arrow in FIG. 1 also effects movement of the shutter members 16 to their closed position, and movement of the rack 21 in the opposite direction by spring 21A elfects opening of the shutter member 16.

When the machine contains no hydraulic fluid, and the shutter members 16 are in the position in which they interrupt flow of air between the rotor and stator, little or no windage effect is experienced.

In the embodiment shown in FIG. 3, there is a split casing part 46, generally similar to the casing part 12B of FIG. 1, housing a rotor 47 and having an annular land 48 with studs 49. Four shutter members are grouped in

opposed pairs

50A, 50B. The shutter members 50A have a common pivotal connection 51A with the casing part 46, and the shutter members 50B have a common pivotal connection 51B with the casing part 46 which is diametrically opposed to pivotal connections 51A. The

shutter members

50A, 50B of each pair extend circumferentially in opposite directions and the adjacent free ends of the

members

50A and 50B overlap. Each free end of the shutter member has a circumferentially directed slot 52.

The

shutter members

50A, 50B can be pivoted on the pivot 51A, 51B respectively between an open position and a closed position in which they interrupt flow of air and hence the windage effect between the rotor and. stator I 3 when the machine contains no hydraulic fluid. The means for effecting such movement consists of a pair of hydraulic rams 53 in the casing wall for closing the members and acting on

arms

54A, 55A of a lever device having a pair of bellcrank levers with a common pivot point coincident with the pivot 51B, the

other arms

54, 55 of the levers overlaying a pair of shutter members 503. At the free end of each of the

arms

54, 55 there is an axial pin 56'projec'ting into the slots 52 of the overlapping

shutter members

50A, 50B. A compression spring 57 for effecting closing of the shutters acts on the

arms

54A, 55A and urges the lever device to move the members 50A, 503 to a position in which the air transmission effect or windage effect is interrupted whenever the pressure in the rams 53 is removed. I I

Rams 53 are controlled by a control valve 58 which also controls, through a hydraulic ram 58A and a valve in a casing 22A, the amount of hydraulic fluid supplied to the machine. The control valve 58 may be operated by known control means, for example hydraulic or pneumatic through a pipe 59 or by mechanical control means.

When there has to be interaction of the hydraulic fluid between the rotor and stator so as to cause a braking effect on the rotor, the control valve 58 is first operated so as to actuate the

rams

53 and 58A in a direction such that the

shutter members

50A, 50B are held open by the lever device, and fluid is fed into the machine via the valve in the casing 22A.

If it is desired to remove the braking effect, the control valve 58 is actuated so that the hydraulic fluid supply is cut off and the hydraulic pressure in the rams 53 falls, and the spring 57 then acts on the

arms

54A, 55A so that the pins 56 move radially inwards, causing the shutter members 50 to close and interrupt air flow between rotor and stator.

It is not necessary that there be four shutter members, as any even number of such members may be used.

By pivoting the shutter members on a stationary fixture, a quick, reliable operation is obtained.

In the embodiments described, the control systems are so arranged that the shutter members cannot be moved to their closed position while there is hydraulic fluid in the vortex path, and hydraulic fluid cannot be admitted while the shutters are closed.

Modifications may be made, for example the rotor and stator could be provided with blades,'instead of pockets.

We claim:

1. A fluid machine comprising a casing, a rotor and a stat-or received in the casing, reaction elements in the 0pposed faces of the rotor and stator cooperable when in fluid communication with each other to generate fluid forces resisting rotation of the rotor relative to the stator, a plurality of shutter members mounted between the rotor and stator for selective movement between a closed position to interrupt the fluid flow between'the rotor and stator and an open position permitting fluid flow between the rotor and stator, said shutter members comprising arcuate blades pivotally mounted at one end of the casing, control means for actuating said shutter members, said control means including a rotatable adjusting ring connected with said shutter members operable upon rotation in opposite directions to open and close the shutter members, a movable control valve for controlling fluid flow to the casing, gear means interconnecting the control valve and adjusting ring operable to rotate the adjusting ring in opposite directions in response to movement of the control valve in opposite directions, said gear means including a rack slideably mounted on the casing, and movable in opposite directions by said control valve, and a toothed segment mounted on the adjusting ring in engagement with said rack.

2. A fluid machine as claimed in claim 1 further including a pin on each shutter member spaced from the pivotal axis of the shutter member, and a plurality of radial slots in the adjusting ring each receiving one of said pins, the engagement of said pins and slots transmitting rotation of the adjusting ring to the shutter members to cause pivotal movement of the shutter members between open and closed positions.

References Cited UNITED STATES PATENTS 1,595,657 8/1926 Halloran 2512l2 XR 2,649,272 8/1953 Barbato 251--212 3,023,581 3/1962 Langlois et a1.

FOREIGN PATENTS 960,671 6/1964 Great Britain.

MILTON BUCHLER, Primary Examiner. G. E. A. HALVOSA, Assistant Examiner. I