US 3754576 A
A fluid amplifier having a fluid flow inlet, a pair of fluid flow outlets, a control fluid flow inlet and a pivotable triangular flap member located in the branching point of the fluid flow outlets, said member being located downstream of the control fluid inlet and adapted to open either of said fluid flow outlets. The flap member is free from direct actuation by the control fluid but is actuated by the fluid flow guided into either outlet and is pivotably journalled about an axis located within the triangular contour, whereby the flap member is automatically switched over to a position with the selected active outlet opened and the other passive outlet completely closed.
Claims available in
Description (OCR text may contain errors)
United States Patent 1191 Zetterstriim et a1.
1451 Aug. 28, 1973 FLAP-EQUIPPED POWER FLUID AMPLIFIER I  inventors: Karl Axel Zetterstriim,
Trollhattan; Tage Lennart Wetterstad, Ljungby; Per-010v Abrahamsson, Opalgatan, all of Sweden I  'Assignee: Volvo Flygamotor AB, Trollhattanj Sweden  Filed: May 21, 1971  Appl. No.: 145,781
 Foreign Application Priority Data I Sweden 16401/70 Dec. 3, I970 521 vs. c1. 137/829, 235/201 ME 51 1-1. 01. F15c3/00 7 581 Field Search 137/815 5 1' References emu UNITED STATES PATENTS 3,053,276 9/1962 Woodward l37/81.5 3,605,780 9/1971 Kranzm. 137/815 3,276,463 10/1966 Bowles 137/81.S
3/1971 Verhelst et a1. 137/815 3,621,859 11/1971 Scott 137/81.5 3,623,496 11/1971 Kawabata.... 137/815 3,638,671 2/1972 Harvey et a1. 137/815 3,640,133 2/1972 Adams 137/816 3,640,256 2/1972 Mangion 137/81.5 X
Primary Examiner-Samuel Scott Attorney-Summers & Young  ABSTRACT A fluid amplifier having a fluid flow inlet, a pair of fluid flow outlets, a control fluid flow inlet and a pivotable triangular flap member located in the branching point of the fluid flow outlets, said member being located downstream of the control fluid inlet and adapted to open either of said fluid flow outlets. The flap member is free from direct actuation by the control fluid but is actuated by the fluid flow guided into either outlet and is pivotably journalled about an axis located within the triangular contour, whereby the flap member is automatically switched over to a position with the selected active outlet opened and the other passive outlet completely closed.
3 Claims, 14 Drawing Figures ELAR-EQUIPPEDEBOWER FLUID AMPLIFIER The present inventiontrclates to afluid amplifierhaving a fluid flow inlet, apair of fluid flow outlets' at'least one control fluid inlet and at least oneflapmemberlocated in the'branching .point of 'the-fluid tflow outlets,
said member being pivotable and having a triangular contour in plan view and adaptedto openeitherof said fluid flow outlets.
The .fluid amplifiers originally developed, 'i.e., those den unintended adjustments of the flap member. Furthermore, the adjustment ofthe flap "member can be controlled with small control-fluid pulses so that the fluid amplifier has a high rate'of'amplification. The direction of the flow also can be changed very quickly,
- and thefluid amplifier can bear very high loads and progressively or suddenly over to the passive outlet.
For this reason, such a common fluid .amplifier without movable part has not been able to provide any substantial output and has thus not been usable as an output stage in a fluid amplifier system.
To eliminating Such major drawback of said fluid amplifiers, attempts have been made to arrange valve means such as flaps in such fluid amplifiers. An example of this is the disclosure of the U.S. Pat. specification No. 3,053,276. The structure according to said patent specification involves a certain improvement of the fluid amplifier and removes to a certain extent the drawback of instability as mentioned, but it has also turned out to have serious disadvantages. The structure stated in said U.S. Pat. specification No. is such that the control fluid flow directly acts upon the valve flap arranged at the outlets of the fluid amplifier, and therefor a significant control fluid pressure must .be sacrificed to provide a switch-over. Also, the structure according to said Pat. specification cannot bear any greater load since, the greater the pressure of the active outlet, the more the flap will be pressed against the adjacent wall, and this finally will make it completely impossible tqm vs t lap The present invention nowaimes. at theelimination 'thq abo e-stated drawbacksv and 1 disadvantages and. to provide a fluid-amplifier of the kind stated, in which effects of hitherto inconceivable magnitude can be obtainfid withoutany detrimental effects at allconcerning the reliability of the switch-over" function.
The feature; substantially distinguishing the present invention is .thatthe flap-member; is free from direct actuation bythe. controlfluid but is1instead actuated bytheintroduetion of-the fluid-flow into either of I theoutletsso that the-flap member then automatically will be switched over to aposition; with the selectedactiveoutlet opened and the, other passive outletzcompletely closed, said; flap member" being; pivotably joumalled about. aaaxislocated. within the; triangular contour.
As, will be; Qvid'cnt-fromthe following; in the inventiontheflap. member-accordingto thestatedxUS patent specification has, in effect, been turned. around and been. -pro,vided;with a contrary shape. ,andthereby the particularly advantageous effect hasbeen: obtained. that the main jet Qanbecaused to move the flap member instead of the control fluid; flow as. in the. last-mentioned art structure;
The invention; also. has aplurality of other important advantages. Firstly, it of courseprovidescomplete reliability with. complete elimination ofprogressi-veorsud:-
gives small pressure losses. Therefore, the fluid amplifier according to the present invention also is very well suited for connection with a fluid amplifier system, contrary to a mechanical valve. Finally,the device of course can be used forgaseous fluids as well as liquids.
By way of example, the invention will be further described below with reference to the accompanying drawings, in which FIG. 1a and lb is a plan view in section and a longitudinal side elevational section of a principally basic embodiment of the invention;
FIGS. 2, Lia-3c and FIGS. 4a-4c are various possible applications of said basic inventive principle;
FIGS. 5-9 illustrate a further embodiment of the present invention, wherein FIG. 5 is a sectional plan view, FIG. 6 a longitudinal side elevational section, FIG. 7 an end sectional view, FIG. 8 an exploded perspective view and FIG. 9 a flow diagram of said further embodiment.
In FIGS. la and lb thus is illustrated a common bidirectional fluid amplifier having afluid flow inlet 1' and two fluid flow outlets, one denominated a for active and the other p for passive. The fluid flow entering from the inlet thus passes out through theoutlet a in the condition illustrated in FIG. la. Furthermore there are illustrated two control fluid inlets s and s,, i"espec tively, from which a controlling fluid pulse can be directed towards the fluid flow jet in thefluid amplifier and cause the same to be switched over from one of the outlets to the-other, the outlets then .of course interchanging their denominations a and p.
According to the present invention, in the branching point between the two fluid flow outlets, is arranged a flap member I, which has triangular shape in plan view and in the present particular embodiment has the shape of a sector of a circle, such as is illustrated in FIG. la. Saidflap member I is pivotally joumalled about a'pivot 2, which is located adjacent the peak of the circle sector or the center of the circular are surface. Said circular are surface of the flap member is located downstream of the pivot 2 and is spaced with smallest possible clearance from the end surface 3 of the partition wall between the two fluid flow outlets at their branching. Said end surface suitably has a contour shapefollowing as close as possible the circular arcuate surface of the flap member. Said flap member 1 is freely pivotably joumalled on the pivot 2. v
The operation of the flap member 1 is as follows: in the condition illustrated in FIG. la, the flap member gives-a free passage to the fluid flow jet going from the.
inlet to the active outlet. When a control fluid pulse is applied to the fluid amplifier through the control fluid amplifier will be-the active one while the previous'ac tive outlet now becomes the passive. In said passive outlet then resides a low pressure, while in the other portions of the fluid amplifier a substantially greater pressure is maintained. Since the flap member l'has a cylindrical surface at its down stream side, the pressure of the passive outlet p cannot act upon the flap member in either direction. The flap member will be maintained in its position against the wall by the pressure differential resulting from the fact that the passage at the flap member I in the active outlet by its shape and location will operate as a diffuser.
In expanding upon this basic idea, develop a number of modified embodiments giving extremely important and surprising advantages in a number of various applications. Some of said applications are illustrated in the drawings, FIGS. 2-4. In FIG. 2, there is illustrated an embodiment of the invention which is particularly well suited for application in hydraulic devices, thus having liquids as the flowing medium as well as the controlling fluid. In this case, the flap member 1 has triangular shape, with however a contour at the base which is of opposite cylindrical configuration from the shape according to the first-mentioned embodiment; thus, the triangular flap member base is concave. Furthermore, the pivot 2 is not mounted adjacent the flap member peak but closer to or substantially at the center of gravity of the flap member. Said embodiment of the flap member peripheral contour and particularly the base line contour now makes it provide to provide a feedback conduit r at the end surface of the partition wall between the fluid flow outlets eetwe fl eebshale their branching. Said feed-back or return conduit r has proved'to provide a particularly advantageous effect whenapplying the invention to fluids. Since liquids are substantially incompressible, fluid leaving the active fluid flow outlet can be returned in a very advantageous manner in an opposite direction through the passive fluid flow outlet so as to then be guided by the concave surface of the flap member 1 into the return flow conduit r. When designing the flap member, attention must be paid to the pressure distribution over the concave base surface of the. flap member.
A further improvement of the idea being the basis for the embodiment according to FIG. 3 leads to the embodiment of the FIGS. 3a-3c. Said latter embodiment provides several different functions. The feature substantially distinguishing said embodiment is that there are two flap members la and lb, respectively, arranged side-by-side in the same manner as the single flap mem ber l in the preceding embodiment. With said design as illustrated in the drawings, with a permanent control fluid flow which is kept equal in both control fluid inlets s and s respectively, the flow jet can be brought to flow from the inlet straight through the fluid amplifier between the two flap members la, lb, and out through the return conduit, which in this particular case can be considered as an outlet and therefore is denominatedu. The two fluid outlets are then connected to either side of a piston in a cylinder as illustrated in the drawings, the piston in this position of the fluid amplifier and its flap member then being free. When changing the mutual size of the control fluid flows through the control fluid inlets s and s respectively, such that s, s as illustrated in FIG. 3b, a proportional control will be achieved, such that the piston 5 will move slowly, dependent upon the fact that a portion of the fluid flow is guided out through one fluid flow outlet while the remainder of the flow will be carried between the flap members directly to the outlet u. Fluid expelled from t'he 'opposite side'of the piston will return through the passive fluid flow outlet and pass the actual flap member, in this case flap member la, and be guided to the outlet 14. When the relative size or ratio between the control fluid flows changes to the point that the control fluid flow in the inlet s completely ceases and control fluid is introduced only into the control fluid inlet s the condition illustrated in FIG. 30 will be obtained, wherein a bi-directional control similar to a memory will be obtained, he, the piston is actuated by full pressure.
It is to be pointed out that this last-described embodiment of course can be modified in its turn and furthermore be inverted or adapted in many other ways which are obvious to those skilled in the art without leaving the scope of the basic inventive thought. Furthermore it is to be pointed out that, in the present embodiment,
both flap members are made as an intermediate step between the flap member shapes in the two preceding embodiments, i.e.,the flap means are mutually equal and shaped as a sector of a circle and pivotably journalled adjacent their peak, being however provided with a base surface which is concavely, circularly arcuate or cylinder-shaped.
It has turned out to be possible to expand still further upon the basic inventive concept. FIGS. 4a-c illustrate each a practical embodiment of the basic inventive concept wherein the speed in the switching over and a low energy loss is of essential importance. FIG. 4a illustrates the fluid amplifier according to the invention utilized for providing a guiding reaction force at each of the fluid flow outlets. If an oscillation is desired in the present case, this can be provided by the inertia of the flap member I or by having a feed-back of fluid through a capacity.
FIG. 4b illustrates how a piston force can be made useful, the comers or edges 4 in the down stream direction of the flap member 1 being made resilient, e.g. in the form of rubber ribs. FIG. 4c illustrates how the fluid amplifier can be utilized for directly providing a rotational movement or a rotational momentum.
Common conditions for the designing of fluid ampliflers according to the present invention firstly are that the lighter the flap member 11, the faster operation. If the pivot of the flap member 1 coincides with the center of gravity of said member, the flap member will not be subjected to any gravitational forces. To allow switching over or adjustment, the fluid flow jet or the main jet must not be completely blocked but instead some minimum flow must continually be provided. When, for example, a piston such as 5 has reached its end position, full pressure will be provided the whole way from the piston to the source, also in the control fluid conduits. The capability of switching over by means of a control fluid flow and the capability of having a fluid amplifier function cannot be provided unless a check valve, a by-pass valve, or the like opens and admits a small flow. This, however, also can be obtained by making the corners or down stream located edges 4 of the flap member 1 resilient as mentioned, so that a predeten'nined flow always is allowed to leak from the active to the passive fluid flow utlet at maximum pressure. However, the flap member should be designed so that the leakage from the active to the passive fluid outlet will be low.
When very high pressures are utilized, there can still be a minor but detrimental load sensitivity of the above-described embodiments. To eliminate this 'sensi-.
tivity, a further improved embodiment can be utilized such as illustrated in FIGS. 5-9 of the drawings.
Similar to the preceding embodiments, in the branching between the fluid flow outlets is mounted a flap member I, but at its base side opposite to the pivot 2, which base side suitably is circularly arcuate, there is provided a connecting conduit 6, extending substantially parallel to said base side. At each end, said conduit 6 opens in a port or aperture at right angles to the plane of the flap member 1. Similarly, the two outlets a and p are connected to outlet conduits opening at right angles to the plane of the flap member. Between said outlet conduits a return condiut u to the power fluid source is also provided.
Because of the connecting conduit 6 in the flap member, a by-pass of a fluid flow returning through the respective outlet to said return conduit is permitted as is the case also in several of the preceding embodiments. In the present embodiment however, there is obtained a complete balancing of the forces acting upon the flap member 1, and therefore the same become very insensitive to loads. Another advantage is that, when making the fluid amplifier in a sandwich structure such as illustrated in FIG. 8, it is possible to have the connecting conduit 6 open to both sides of the triangular flap member, the conduits leading from either side of said flap member then being connected to each other to provide a common connection exteriorly of the fluid amplifier to only one side thereof.
1. A fluid amplifier having in combination:
a pair of fluid flow outlets;
at least one control fluid inlet;
at least one pivotable flap member which is of generally triangular contour in plain view and located downstream of the control fluid inlet so as to be non-responsive directly to fluid entering said control fluid inlet, said member being pivotably journalled about an axis located within its triangular contour and selectively operable between two distinctively different positions in each of which said fluid flow inlet communicates for fluid flow with a respective one only of said fluid flow outlets, said flap being actuated from a first to a second of its two positions only in response to the momentary diversion of the direct flow path between said fluid flow inlet and the then-active fluid flow outlet in response to an input to said control fluid inlet which momentary diversion causes said fluid to impinge upon sai flap and quickly actuates said flap to its second position,
and a partition wall between said fluid flow outlets defining therein a return conduit, said triangular flap member having a downstream base side formed with a concave configuration towards the center of gravity of said flap member for allowing the by-pass of a return fluid flow through the passive outlet back through the return conduit. 2. A fluid amplifier according to claim 1, characterized in that two flap members are arranged side-by-side substantially in register with each edge of the return conduit in the partition wall.
3. A fluid amplifier having in combination: a fluid flow inlet; a pair of fluid flow outlets; at least one control fluid inlet; at least one pivotable flap member which is of generally triangular contour in plain view and located downstream of the control fluid inlet so as to be non-responsive directly to fluid entering said control fluid inlet, said member being pivotably journalled about an axis located within its triangular contour and selectively operable between two distinctively different positions in each of which said fluid flow inlet communicates for fluid flow with a respective one only of said fluid flow outlets, said flap being actuated from a first to a second of its two positions only in response to the momentary diversion of the direct flow path between said fluid flow inlet and the then-active fluid flow outlet in response to an input to said control fluid inlet which momentary diversion causes said fluid to impinge upon said flap and quickly actuates said flap to its second position,
said flap member having the shape of a sector of a,
circle with the partition wall between the fluid flow outlets closely following said sector periphery,
said flap member adjacent its circularly arcuate base side opposite the pivot axis being provided with a connecting conduit extending substantially parallel to said base side and at each end opening to at least one port at right angles to the plane of the flap member and adapted to be connected with, at one hand, a respective one of said outlets and, on the other hand, with a return conduit arranged between said pair of outlets and adapted to allow a by pass of a fluid flow returning through said respective outlet to said return conduit,
said pair of outlets as well as said return conduit being arranged to open into the fluid amplifier chamber at right angles to the plane of the flap member in register with the ports belonging to the connecting conduit.