US2936152A - Structure forming and adjustable orifice - Google Patents

STRUCTURE FORMING AN ADJUSTABLE ORIFICE 3 Sheets-

Sheet

1 Filed Aug. 27, 1957 .Flig E INVENTOR. WENDELL E. RENICK BYCE W AGENT.

Fig. 2 is a view in section of the valve described in Fig. 1, the view being taken on

line

22 thereof and showing particularly the mechanism thereof which forms an adjustable orifice in the valve and the adjusting mechanism by which this adjustable orifice is adjusted in two directions and is held in the position to which it is adjusted;

In Fig. 1 of the drawings, there is shown a hydraulic circuit or system which includes an adjustable .volume constant

flow control valve

10 in which there is incorporated an adjustable orifice forming means which includes the features of the invention. The hydraulic circuit includes a reservoir or tank 11 for hydraulic fluid, a

pump

12 which receives fluid from the tank 11 through a

conduit

13 and discharges fluid under pressure into a

conduit

14.

Conduit

14 is connected to tank 11 through a

relief valve

15. The tank, pump, etc. thus far described constitute a source of fluid under pressure by which a hydraulic ram or

motor

16 is operated.

The

high pressure conduit

14 is connected to the inlet port of a manually operated directional

flow control valve

17. Valves similar to the

valve

17 are well known in the art and, therefore, this valve is not shown in detail.

valve

17 illustrated includes a manual control handle or

lever

18. When the

lever

18 is in the position shown, the

conduit

14 is blocked at the

valve

17 and the entire output of fluid from the

pump

12 is by-passed through the

relief valve

15 to tank 11. When the

lever

13 is shifted in one direction from the position illustrated, the

conduit

14 is connected to a conduit 19 leading to

valve

10 and fluid will flow through this latter valve to a

conduit

20 connected to the top of the ram or

motor

16. Conduits 19 and 21) are interconnected by a by-

pass conduit

21 which includes a

check valve

22 that prevents fluid from flowing from the conduit 19 to conduit 20 but which permits sub-. stantially free flow in the opposite direction, that is, from the

conduit

20 to the conduit 19. The purpose of this by-

pass

21, 22 in the reverse direction is fully set forth hereinafter.

Hydraulic fluid under pressure which is directed to the top of the cylinder of the ram or

motor

16 forces the

piston

23 thereof downwardly and displaces hydraulic fluid from the bottom of the cylinder. The displaced fluid flows through a

conduit

24 to the

valve

17 and through a

conduit

25 to the tank 11.

When the

lever

18 is shifted in the opposite direction from the position illustrated,

conduit

14 is connected to

conduit

24 and conduit 19 is connected to tank. Under these conditions, hydraulic fluid from the source of pressure flowing in

conduit

14 flows through

conduit

24 to the bottom of the ram or

motor

16 and forces the

piston

23 thereof upwardly displacing fluid from above the piston and through the

conduit

20, the by-

pass conduit

21 and

check valve

22 to the

valve

17 from Which it is directed through the

conduit

25 to tank 11. The

conduit

21 and

check valve

22 may be, and preferably are, contained within the

body

26.

From the foregoing, it will be seen that hydraulic fluid flowing to the top of the ram or

motor

16 must flow through the adjustable volume constant

flow control valve

10 but that when the direction of flow is reversed, the hydraulic fluid flowing from the top of the ram or

motor

16 can by-pass the

valve

10 at low pressure by passing through the

conduit

21 and check Valve 22.

The adjustable volume constant

flow control valve

10 is included in the hydraulic circuit or system for causing hydraulic fluid to be admitted to the top of the ram or motor at a constant volume at any of its volumetric adjustments regardless of fluctuations either in the high pressure supply conduit 19 leading thereto or in the

conduit

20 leading therefrom and to the top of the ram or

motor

16.

The adjustable volume constant

flow control valve

10 includes a

body

26 in the form of a rectangular block having a base or

bottom surface

27 adapted to be mount- The- '26 which surrounds the liner sleeve.

The

body

26 is provided with two through

bores

23 and 29 the axes of which extend at right angles to each other and are spaced apart. The axis of

bore

28 is parallel with the bottom or

base surface

27 of the body and it contains elements which cooperate to form the pressure compensating means of the

valve

16. These elements include a

cylindrical element

30 having spaced

circumferential grooves

31, 32 and 33 formed therein which is inserted into one of the open ends of

bore

23 and is retained therein by a snap ring 34. The

cylinder

30 is sealed to the

bore

28 by an O-ring contained Within the

groove

31 which is adjacent the snap ring 34.

Cylinder

30 also includes a central axially extending cylinder or bore 35 which is connected to the

grooves

32 and 33 by passages or

ports

36 and 37, respectively.

A compound piston element 38 is also contained within the

bore

28 and this element includes a

piston head

39 and a small diameter

hollow piston portion

40 which extends into and reciprocates in the cylinder or bore 35. This small diameter

hollow piston portion

40 includes a circumferential groove 41 and a pair of

lands

42 and 43. The

land

42 cooperates with the ports or

passages

36 to form a valve for controlling the flow of fluid through the ports or

passages

36 in accordance with the axial position of the sharp peripheral edge of the land 4%) which is adjacent the groove =41.

Land

43 functions merely as a guide or bearing for the compound piston element 37 and it never closes the ports or passages 37. The hollow interior of the

piston portion

40 is connected through a lateral drilling with the groove 41 in order that fluid may flow from this groove 41 through the

piston portion

40 and to the chamber formed by its free end and the upper closed end of the cylinder or bore 35.

The

piston head

39 is of such diameter as to sealingly slide in the

bore

28 in the

valve body

26 and the entire piston 38 is urged upwardly to the position shown in Fig. l of the drawings by a spring 44 which abuts the

piston head

39 and a

plug

45.

Plug

45 is inserted into the other open end of

bore

28 and is sealed thereto by an O-ring. A

snap ring

46 retains the

plug

45 in the

bore

28. The

plug

45 forms an

abutment

47 which limits the downward movement of the piston 38 in the

bore

28. The chamber formed in the

bore

28 between the upper face of the

piston head

39 and the adjacent end of the

cylindrical element

30 is connected with the groove 37 by a

passage

48 formed in the cylindrical element and extending from one of the ports or passages 37 to the bottom of the

element

30.

The through

bore

29 contains mechanism which cooperates to form an adjustable or variable orifice by which the rate of flow of fluid to the

exhaust port

20 of the constant volume flow control valve assembly is controlled. The elements which cooperate to form this orifice include a liner, sleeve or

thimble

49 which is contained within the

bore

29 and has a close sealing fit therewith. This

liner sleeve

49 is provided with two

circumferential grooves

50 and 51 which are separated by a

land

52 and its upper end is further sealed to the

bore

29 by an O-ring. As seen in the drawings, this O-ring is contained within a groove formed in the

liner sleeve

49. Another O-ring lies in a groove formed in the body This latter O-ring is retained in its groove by the sub-plate, not shown, and seals the

body

26 to the sub-plate.

Groove

51 in

liner sleeve

49 is connected at all times to the interior of the

sleeve

49 by passage means in the form of a pair of bores or holes 53 formed through the walls of the

sleeve

49 and

groove

50 is connected to the interior of the liner sleeve by a

rectangular slot

54 which is formed through the wall of the sleeve by a milling operation whereby the peripheral surfaces of the

slot

54 where it joins the interior or bore of the liner sleeve will be provided with sharp edges.

The interior or bore of the

liner sleeve

49 is cylindrical and it receives a

valve element

55 which is adjustable therein both axially or longitudinally and rotationally. This

element

55 is a shaft having two

cylindrical portions

56 and 57 of different diameters separated by a

shoulder

58. The

larger diameter portion

56 of

shaft

55 fits closely but movably in the interior of the

liner sleeve

49 to form a substantially fluid tight fit therewith and it is provided with a circumferential groove adjacent the

shoulder

58 in which there is an O-ring for preventing the loss of fluid along the

shaft

55 toward the

shoulder

58. As seen in the drawings, the lower end of the

portion

56 of

shaft

55 is provided with a

circumferentially extending groove

59 which is open to the bores or holes 53 in the

liner sleeve

49 at all times and this

groove

59 joins or is intersected by a notch or

slot

60 milled in the shaft and extending at right angles to the axis thereof. The depth of notch or

slot

60 is such that the bottom of the slot lies substantially on the longitudinal axis of the

shaft

55 and the notch or slot is of greater width i.e., it has a greater axial dimension than

groove

59. As clearly seen in the drawings, the lowermost side wall of notch or

slot

60 lies in the same plane as the lowermost side wall of

groove

59 and because the axial dimension of the notch or

slot

60 is greater than the Width of

groove

59 the

uppermost side wall

61 of the

slot

60 lies in a plane above the plane of the uppermost side wall of

groove

59 to provide a solid

semicircular shaft portion

62 having sharp edges Where it joins the walls of the notch or

slot

60 and which, upon rotary adjustment of the

shaft

55, serves to adjust the length of the adjustable orifice of the

control valve

10 formed by it and the

rectangular slot

54 in the manner hereinafter described in detail.

As previously mentioned, the valve element or

shaft

55 is adjustable both axially or longitudinally and rotationally in the

liner sleeve

49 and the means for adjusting the shaft in these manners includes a bushing or

sleeve

63 which receives the small diameter or stem

portion

57 of the

shaft

55 and which abuts the

shoulder

58 of the latter. This bushing or

sleeve

63 is externally threaded to be received by internal threads formed in the

body

26 at one end of the through

bore

29 and its uppermost end provides a

cylindrical surface

64 upon which there is rotational mounted an adjusting means in the form of a

hexagonal index plate

65.

Index plate

65 may be locked to the cylindrical portion of the bushing or

sleeve

63 by a

set screw

66. As clearly seen in Fig. 4 of the drawings, the

index plate

65 is provided with six equally spaced bores or holes 67 through any one of which a

pin

68 may be inserted. The

pin

68 is received in a bore in the

body

26 and its uppermost end projects above and beyond the top surface of the

plate

65 to provide a stop means for a

dial

69 which forms a cup shaped cover for the adjusting mechanism just described. While I have shown the

index plate

65 as including six of the bores or holes 67, it is to be understood that more or less of these holes or bores may be provided if desired.

The cup shaped dial or cover 69 is employed to adjust the

shaft

55 to different rotational positions and it includes a

wing

70 opposite a

pointer

71 which cooperates with

indicia

72 on a

plate

73 which is secured to the

body

26 by

screws

74. The

dial

69 is mounted upon the

stem portion

57 of

shaft

55 and is held thereto against rotation by a roll pin which extends through the shaft and is received in a slot in the dial. The

circular lip

75 of the dial is flat and it can be clamped against the

body

26 by a

knurled nut

76 which is threaded on the end U of

shaft

55. The uppermost end of

pin

68 extends into,

an

arcuate slot

77 formed in the bottom of the

dial

69 and the ends of this

slot

77 form abutments which engage the

pin

68 to determine the limits of rotation of the

dial

69.

As is evident from the foregoing description, the adjustable or variable orifice of the adjustable volume constant

flow control valve

10 is formed by the milled

rectangular slot

54 in the liner or

sleeve

49 and the milled

slot

60 in the

shaft

55 and the relative positions to which these elements are adjusted determines the eficctive size or open area of the orifice. These elements are shown diagrammatically in Fig. 8 of the drawings, and, with reference to this drawing, it will be seen that when the

upper side wall

61 of the

slot

60 is adjusted axially or longitudinally (upwardly or downwardly as seen in Fig. 8) that the effective width of the

slot

54 will be changed. It will also be apparent that when the

shaft

55 is rotated (moved to the right or left as seen in Fig. 8) that one or the other ends of the notch or

slot

60 and the

semi-cylindrical shaft portion

62 will fupgtion to adjust the effective length of the

slot

54.

In the apparatus herein described, the width of the adjustable orifice is, of course, adjusted by shifting the

shaft

55 to different axial positions, and in the apparatus illustrated the effective open width of the orifice may be adjusted to any one of different widths as predetermined by the rotation of the bushing or

sleeve

63 and the number of

holes

67 in the

plate

65.

In adjusting the relative positions of the elements to predetermine the range adjustments, the bushing or

sleeve

63 is rotated to that position wherein it forces the

shaft

55 downwardly just to the point wherein the adjustable orifice is closed and no fluid can flow through it. The

set screw

66 is then loosened and the

index plate

65 is rotated to such position that the

pin

68 can be inserted through the

hole

67 therein marked 0. The

pin

68 is then inserted through this hole into the bore in the

body

26 and the

set screw

66 is tightened to interlock the

index plate

65 and the bushing or

sleeve

63. Once the valve has been zeroed in the manner described, if it is desired to adjust the orifice to the first range the

pin

68 is Withdrawn from the

index plate

65 and

body

26 and the index plate is rotated until the

hole

67 therein marked 1 aligns with the pin bore in the body and the

pin

68 is replaced. The orifice may be adjusted to any other of the ranges indicated by the

holes

67 marked 2 through in the same manner.

It is understood, of course, that since the

dial

69 forms a cover for the range adjusting mechanism described that it must be removed from the

shaft

55 in order to gain access to the range adjusting mechanism.

After the range adjusting mechanism described has been adjusted to or set in the desired range in the manner described, the

dial

69 and

nut

76 are placed upon the

shaft

55 and

nut

76 is tightened to draw the

shoulder

58 against the bushing or

sleeve

63. In order to adjust the volume in that range to which the orifice has been set, the shaft is rotated to the desired position as indicated by the

pointer

71 and

indicia

72 and the nut is tightened. Tightening of the

nut

76 draws the

shoulder

58 of

shaft

55 against the end of the bushing or sleeve 63' and it clamps the

dial

69 against the

body

26 to lock the

shaft

55 in its adjusted position.

able volume constant

flow control valve

10 is from the high pressure conduit 19 to the

circumferential groove

32 and from this

groove

32 through the passage or

ports

36 to the circumferential groove 41 in small

diameter piston portion

46 of piston 38. From groove 41, the fluid flows through the ports or passages 37 to groove 33 which is connected to a

passage

78 leading to the bores or holes 53 in

liner sleeve

49. From the bores or holes 53, the fluid passes into the

slot

60 in

shaft

55 and upwardly in this slot to the adjustable or variable orifice formed by the

slot

54 and

groove

60. From this orifice, the fluid flows through a

passage

79 to the outlet or

exhaust conduit

20 of the hydraulic system.

As previously indicated, when the adjustable volume constant

flow control valve

10 is operating, itwill maintain a constant volumetric flow at its exhaust port or

conduit

26 regardless of pressure fluctuation therein or in its input port or conduit 19. It is the pressure compensator mechanism which is responsible for this action and it is the variable orifice that predetermines what the volumetric flow through the valve shall be.

In the operation of the pressure compensator mechanism, the compound piston element 38 is urged to the position shown in Fig. I of the drawings by the spring 44 to open the valve formed by the

ports

36 and the sharp bottom edge of the

land

42 of the

piston portion

40. The fluid flowing through this valve enters the groove 41 and flows to the adjustable or variable orifice. The pressure of this fluid is applied from the groove 41 to the top of the small

diameter piston portion

42 and from the groove 41 through the

ports

37 and 48 to the upper piston area of the

head

39. (For the purposes of this explanation, the total area just described will be assumed to be one square inch.) Assuming that the adjustable orifice is closed and that the spring 44 exerts an upward force of thirty-five pounds upon the compound piston 38, as the pressure builds up in the groove 41 it acts on the total piston area described to compress the spring and close the valve formed by the

ports

36 and the lower sharp edge of the

top land

42. It will thus be seen that the force of the pressure in the groove '41 will always be equal to the force of the spring 44- plus any force which may assist the spring. In other words, since the piston 38 is pressure balanced and urged in one direction by the spring 44 with a force of thirty-five pounds, the two forces will always be equal. Having assumed that the area of each end of the

piston

39 is one square inch, it will be seen that the pressure acting on the spool in opposition to spring 44 will equal thirty-five pounds per square inch.

When the adjustable orifice is opened, fluid will begin to flow through it from the groove 41 and the pressure in said groove will be maintained due to the action of in this action, the spring 44 will move the piston 38 upwardly to open the valve at 36 sutficiently to maintain a pressure in the groove 41 equal to the force of the spring. It is well known that when fluid is forced through an orifice that there is created a pressure drop or difference in pressures between the fluid on the inlet side of the orifice and the pressure of the fluid on the outlet side of the orifice. In the present instance, the higher of these pressures is on the inlet side of the orifice and is reflected to the groove 41. The lower of these pressures is on the outlet side of the orifice and is reflected through a

passages

80 to the

bore

28 and the bottom of the

piston head

39. This lower pressure is applied to the

piston head

39 to aid the spring 44 in urging the

piston

39 to open the valve at 36.

From the foregoing description, it will be seen that the construction of the adjustable volume constant

flow control valve

10 is simplified because its

body

26 need only be provided with the uniform diameter bore 29 to receive the

sleeve

49 of the adjustable orifice forming means and that this bore need not be provided with the customary annular grooves for conducting fluid through the

body

26 to and from the

passages

53 and 54 in the sleeve since this is the function of the

grooves

58 and 51. It will also be seen that because of this simplified construction that the orifice forming means or slot 54 included in the

sleeve

49 may be readily changed or renewed simply by replacing the

sleeve

49.

Important features of this invention reside in the method of making the elements of the orifice forming assembly as Well as the assembly itself and in this method the

sleeve

49 is formed by providing a cylindrical sleeve, then grinding or turning the

grooves

50 and 51 therein and finally by milling the

slot

54 therein. The steps of forming the

shaft element

55 of the orifice forming means include turning or grinding its outside or circumferential surface to form a two diameter element including the

cylindrical portions

56 and 57 and turning the

groove

51 therein after which the notch or

slot

60 is milled therein.

It will be seen that when the

sleeve

49 and

shaft

55 are assembled to form the adjustable orifice that the notch or

slot

60 will function to balance the

shaft

55 axially hydraulically within the sleeve, that it forms a passage for conducting fluid between the

passages

53 and 54 in the sleeve and that its sharp edges where it joins the

cylindrical surface

62 together with the

surface

62 cooperates with the sharp edges of the

slot

54 at the interior or bore of the sleeve to form a rectangular orifice the area of which may be adjusted by moving the shaft either axially or longitudinally, or by rotating the shaft within the sleeve.