Patent GB-786956-A (GB)
Title: Improvements in or relating to fluid control devices
IPC: F16F9/50
Filed: 1954-04-05
Abstract: 786,956. Dashpots and hydraulic shock absorbers. DJORDJEVITCH. Y. April 5, 1954, No. 9971/54. Class 108(3) [Also in Group XXIX] A fluid control device comprises a unit formed of at least two individual movable elements 1, 1<SP>1</SP> (Fig. 28) juxtaposed to form a valve-member, and having rectilinear edges A, B, resiliently maintained in mutual contact, one of the faces unit having a bevelled shape 3 to enable the fluid to have a wedge-like action to move the elements 1, 1<SP>1</SP> apart to create a fluid passage. As shown. rings 2 are provided to resiliently maintain the elements 1, 1<SP>1</SP> in contact. The rings 2 (Fig. 28) may comprise split rings, or clips, or may be of tape, or of round, square, or rectangular section wire. They may comprise two concentric split bands (Figs. 7 and 8, not shown). The elements of the control member may comprise two (as shown) or more sectors 1, 1<SP>1</SP> or may be of segmental construction. The control member may be of oval or square cross section. In operation, friction may occur between the ring 2 and the elements 1, 1<SP>1</SP> the latter being knurled for this purpose. When circular and formed of three segments (Figs. 13 to 16, not shown) an aperture with associated bevelled portions may be formed at the two lines of junction between adjacent segments. The diameter of a constantly open orifice 1a may be reduced to zero. The orifice 1a may be of polygonal or oval cross section and may be provided in another part of the control member (Fig. 9, not shown). One pair of bevelled portions 3, 3<SP>1</SP> may be dispensed with. Some or all of the counterbored portions 5, 5, 5a, 5a, may be dispensed with or may be replaced by a single counterbore of part-spherical shape. The expansion of the rings 2 may be limited by the provision of a further ring 2<SP>1</SP>. The bevelled portions 3, 3' may define a pyramidal or conical shape. The rings 2 may be so constructed that their tension varies with change in temperature. The elements 1, 1<SP>1</SP> may vary in size in response to temperature change. The axial length of the bevelled portion may be greater than that of the remainder of the control member (Fig. 40). As applied to a shock absorber (Fig. 40) the control member 1, 1<SP>1</SP> 2, is disposed in a cage 10. spring loaded within a housing in a piston 14. The piston may be carried by a piston rod or as shown, may be a doubleacting piston (one-half, only, shown), operated by an arm 24. A piston type dashpot 44. 45 and coil spring 46 are disposed between the piston 14 and the arm 24, but may be in the form of one or more pairs of opposed resilient dished discs (Fig. 41, not shown) each having a small orifice. On upward movement of the piston (as viewed in Fig. 40) liquid pressure developed in the cylinder 12 tends to expand the elements 1, 1<SP>1</SP>, against the resilience of the ring 2. On downward movement of the piston, the whole member 1, 1<SP>1</SP>, 2, and cage 10 lifts against a spring 18 to permit return flow of liquid. Flow between opposite ends of the piston is also provided by a passage 25 (or two such passages) having a restricted orifice 25a at one or both ends or intermediate the ends. This passage may alternatively be disposed in the wall of the cylinder 15 (Fig. 52, not shown). A rod may extend axially from one end of the passage 25 to a point at a predetermined distance from the orifice 25a. The rod expands with increase in temperature to approach the mouth of the orifice 25a and thus progressively increase the resistance to flow. The end of the rod may carry a tapered metering rod which actually enters the orifice 25a. The elements 1, 1<SP>1</SP> may have axially-extending projections (Fig. 4, 6, not shown) to decrease the bearing area of the elements and so permit it to slide freely relative to the cage 10 and piston 14. There may be a seal ring filling the annular space between the outer periphery of the ring 2 and the corresponding inner peripheral surface of the cage (Fig. 43, not shown). Alternatively a sealing washer may be disposed between a rigid washer mounted on the upper faces of the members 1, 1<SP>1</SP>, 2, and the flange 10a of the cage 10. Ports may be formed in the flange 10a (Fig. 47, not shown). The cage 10 may be formed with axially and radially directed grooves in its peripheral surface and upper end face respectively. In an embodiment (Fig. 44, not shown) the member 1, 1<SP>1</SP>, 2 is disposed directly in the piston cavity without a surrounding cage 10, and the ring 2 is replaced by radially disposed coiled springs respectively abutting between recesses in the piston and elements 1, 1<SP>1</SP>. The spring 18 (which in this case bears directly on the member 1, 1<SP>1</SP>, 2) is a dished-shaped spring washer. In the piston 14 shown in Fig. 37 the control member comprises elements 1a, 1<SP>1</SP>a pivotally mounted at 31, 31<SP>1</SP> and loaded by coiled springs 32, 32<SP>1</SP>. In a modification (Fig. 36, not shown) the elements 1a, 1a<SP>1</SP>, instead of being pivoted at 31, 31<SP>1</SP> are secured by a clamping ring. Under compression of the piston 14 in its cylinder, the elements la, 1a<SP>1</SP> spring apart. A spring loaded one-way valve disposed in a passage (not shown) leading between the interior 16 of the piston and the upper end face of the piston, controls flow in the opposite direction. A complete shock absorber is described (Fig. 32, not shown), a pair of valves similar to that shown in Fig. 28 are provided to control flow in each direction through a piston carried by a piston rod. A chamber at the end of the cylinder opposite to the end through which the piston rod works, is closed by a valve assembly comprising a control member 1, 1<SP>1</SP>, 2, within a spring-loaded cage 10. On inward telescopic movement, liquid displaced by the piston rod lifts the cage 10 and member 1, 1<SP>1</SP> 2 bodily. On rebound, liquid has to force its way back through between the elements 1, 1<SP>1</SP>. In Fig. 48, a piston 62 carrying a stem 64, is slidable in the cage 10. Pressure acting on the piston 62 causes the stem 64 to bear on the bevelled portions of the elements 1, 1<SP>1</SP> and thus assists in the spreading of these elements. In Fig. 53 is a piston 14 with a valve assembly which is auxiliary to the control member 1, 1<SP>1</SP>, 2. A valve 70 lifts against a spring 79 to permit flow from the inside 16 of the piston to the upper cylinder chamber 15. In the valve 70 is mounted a stem 73 having a tapered end which co-operates with an orifice 72 in the face of the piston. A spring 78 acts between a collar 73a on the stem 73 and the base of a recess 77 in the valve 70..On upward piston movement, liquid initially flows through orifices 75, 81, before increased pressure lifts the stem 73. Liquid then flows through the orifice 72 into the recess 77, back into the stem through ports 76, and out again through triangular, oval, or square ports, 82 which are progressively opened to the chamber 16. In a modification, the whole cross section of the bore of the stem 73 is open to the chamber 16 and there are no ports 82. In a further modification (Fig, 52, not shown) the tapered end-portion of the stem 73 is replaced by an end face which is urged by the spring 78 into valve-seating engagement with the orifice 72. In this construction, the valve 70 is dispensed with, the recess 77 being formed directly in the piston. In a modification (Fig. 51, not shown) of the last construction, the recess 77 is formed to one side of, instead of coincident with, the axis of the piston 14. In a simpler construction of auxiliary valve (Fig. 49, not shown), the valve assembly 70 and valve stem 73 are replaced by a single spring-loaded flap valve, which may, or may not, be formed with an orifice. The invention is also applicable to the pistons of pumps (Figs. 38, 39. not shown), resulting in an output flow which may be laminated or atomized.