US2278310A

US2278310A - Hydraulic tripping mechanism

Info

Publication number: US2278310A
Application number: US393200A
Authority: US
Inventors: Gottlieb Manious
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1941-05-13
Filing date: 1941-05-13
Publication date: 1942-03-31
Anticipated expiration: 1959-03-31

Description

March 31, 1942. O T EB 2,278,310

HYDRAULIC TRIPPING MECHANISM Filed May 13, 1941 WITNESSES:

INVENTOR WJKWM 2 Mnmggs GOTTLIEB. 5. WWW

. ATTORNEY Patented Mar. 31, 1942 HYDRAULIC TRIPPIN G MECHANISM Manious Gottlieb, Philadelphia, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania,

Application May 13, 1941, Serial No. 393,200

6 Claims.

The invention relates to hydraulic mechanism for moving a suitable element and it has for an object to provide apparatus of this character wherein the mechanism shall include a piston arrangement responsive to decline in fluid pressure to effect movement of the element and responsive to increase in fluid pressure after operation due to pressure decline to reset the mechamsm.

A further object of the invention is to provide an element, such as a trip lever, which is moved by means of a rod having associated therewith outer and inner pistons biased by means of springs to move in one direction against the force of fluid pressure, the arrangement being such that, upon decline in fluid pressure to a predetermined extent, the pistons move to effect movement ofthe element, and such that, with restoration or increase in fluid pressure to a predetermined extent, the pistons are returned to normal position.

A further object of the invention is to provide a device which is responsive to decline in oil pressure to a predetermined extent to operate a trip lever for bringing a suitable machine to a stop, the mechanism being so constructed and arranged that, when the oil pressure thereafter builds up to a predetermined extent it is reset;

the mechanism including a piston arrangement subject to oil pressure and springs which exert the necessary force, in the event of sufiicient drop in oil pressure, to cause movement of the mechanism to effect tripping of the lever or its equivalent.

These and other objects are effected by the invention as will be apparent from the following description and claims taken in accordance with the accompanying drawing, forming a part of this application, in which:

The figure is a longitudinal sectional view of ably the conventional lever moved in response to decline in oil pressure to bring about stoppage of a suitable machine, such as, an elastic-fluid turbine.

The mechanism, at l, includes a cylinder 3 head I5 and the bore extending from the radial abutment face toward the first head l4.

An outer annular piston 20 fits the bore l6, it has an annular conical valve seat 2| disposed adjacent to its inner periphery, and it has a radial flange 22 disposed in the bore H, the flange having a radial face 23 for cooperation with the radial abutment face I8, as will be hereinafter pointed out.

An inner piston 24 has a peripheral edge 25 providing a valve member for cooperation with the annular valve seat 2|.

Preferably, the first cylinder head I 4 has a sleeve 26 extending inwardly therefrom into the cylinder, the sleeve having a bore 21 providing a guide for the rod I2 and having its external surface 28 providing a guide-way for the inner piston 24, the latter preferably having a hub or tubular extension 29 in telescopic relation with respect to the sleeve or tubular member 26.

The rod |2 has its inner end 3| disposed a substantial distance within the cylinder from the inner or abutment end 32 of the sleeve or tubular member 26 and the inner piston is connected to the inner end 3| of the rod. As shown, the inner piston has a sleeve or hub portion 33 extending from the side thereof opposite to the hub or sleeve 29 and it has an inwardly-extending radial flange 34 providing a bore 35 for reception of the inner end portion 3| of the rod. The rod has a shoulder 36 engaging one side of the flange and the other side of the latter is engaged by a nut 31 carried by the rod. Thus, the inner piston is positively connected to the rod so that the two move together.

A first or outer helical spring 38 has one end engaging the spring shoulder 39 formed on the outer piston 20 and its other end engaging the spring seat 40. Within the spring 38, there is arranged a second or inner helical spring 4| having one end engaging the inner piston 24 and its other end engaging the seat 40. The spring seat 40 is disposed adjacent to the second cylinder head I5 and it is adjustable axially of the cylinder by means of the stem 42 having threaded engagement with respect to the cylinder head I5 From the structure so far described, it will be seen that the outer and

inner pistons

20 and 24 normally divide the interior space of the cylinder into a fluid pressure chamber 43 and into a spring space 44. The cylinder is provided with a fluid pressure passage 45 for communication with any suitable source of oil pressure, and it has one end 46 in open communication with the interior of the space or chamber 43. Thus, it will be seen that fluid pressure supplied to the chamber 43 is applied to the piston areas of the outer and inner pistons 20 and 2d and facing toward the first piston head it, the .forces of fluid pressure so applied to the pistons being opposed by the forces acting in the other direction and due to the springs 38 and 4H.

The outer and inner springs 38 and 4| have different scales, the inner spring having the larger scale. For example, the scales may be such that, for the piston areas and from the po-- sition of the pistons shown on the drawing, the inner piston 24 will start to move toward the cylinder head M when the fluid pressure in the space 43 is at 3 pounds per square inch while the piston 20 will start to move in the same direction when the pressure is at 2 /2 pounds per square inch. On the other hand, assuming that the pistons have moved inwardly toward the cylinder head I 3 with reduction in forces of the springs, then movement of the inner piston 24 toward the cylinder head 15 will start when the pressure reaches 1 pound per square inch and the outer piston 20 will start to move in the same direction when the pressure reaches 1 /2 pounds per square inch.

Assuming that the outer and inner pistons are in the position shown and that the oil pressure starts to decline, when the pressure has declined to 3 pounds per square inch, the inner piston starts to move toward the first cylinder head [4, but, as the outer piston 26 cannot move to the left until the pressure declines further to 2 pounds per square inch, relative movement of the inner piston toward the cylinder head Ill and with respect tothe outer piston takes place, with the result that, due to separation of the peripheral edge or valve member '25 from the conical valve seat 2|, sudden drop in pressure in the chamber 43 and escape of oil therefrom occur and render the two springs effective to move both pistons 2H and 24 and the rod I?! in the direction of the cylinder head 54, the rod moving toward the lever or element is and the last portion of its motion in that direction being utilized to impart tripping movement to the latter.

Assuming that the pistons 2i? and 2d have moved to their extreme positions toward the cylinder head M, this movement being limited by the abutment end 32 of the sleeve is engaging with the shoulder (iii and the conical valve seat 2| of the outer annular piston 26 engaging the peripheral edge 25, and that the fluid pressure starts to build up in the chamber #13, when the pressure reaches 1 pound per square inch, the inner piston 24 starts to move toward the right or toward the cylinder head 55; however, as the outer piston 2i] cannot be moved by the pressure until a higher value, for example, 1 pounds per square inch is reached, both pistons move together, as the pressure increases, until the parts are in the initial position shown.

As hereinbefore pointed out, the shoulder 38 and the end 32 of the sleeve 26 limitmovement of the pistons toward the left or toward the cylinder head M, the peripheral edge 25 and the valve seat 3| cooperating to limit such movement of the outer piston 29 in that direction. Movement of the pistons toward the right or toward the cylinder head is limited by means of the flange face 23 engaging the radial abutment face [8, the valve seat 2! cooperating with the peripheral edge 25 of the inner piston 24 to limit movement of the inner piston in that direction.

Because it is desirable to use springs of standard sizes or scales, and as the same adjustment is made for both springs, I prefer to provide the outer piston with a differential feature so that, as the outer piston reaches the position at which the flange face 23 engages the abutment face IS, the pressure in the chamber 43 is effective to apply increased force to the outer piston, the larger piston area of the latter then being effective, and so that, when the pressure declines to a value such that the outer piston may move away from the abutment face I8, just as soon as separation starts, the effective area of the outer piston 21'! is reduced to its lower value, with the result that, without further decline in pressure, the force of pressure acting on the piston is lessened to the extent of decrease in piston area. Thus, as the outer piston 20 engages the abutment face 18, the force of fluid. pressure acting on the outer piston is suddenly increased as the larger area thereof becomes effective, and, when movement of the outer piston away from the abutment face l8 starts, the force of fiuid pressure is suddenly decreased because the smaller piston area then becomes effective. In other words, there is provided a force differential acting on the outer piston and tending to hold the latter seated through a margin of pressure change depending upon the piston area change; and this makes it unnecessary to complicate the springs by having the latter or scales correspond exactly to desired pressure conditions or by the provision of means for effecting relative adjustment thereof.

While the invention has been shown in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof, and it is desired, therefore, that only such limitations shall be placed thereupon as are specifically set forth in appended claims.

What is claimed is:

1. The combination with an element to be moved, of mechanism including a rod having a range of axial movement and 50 disposed in relation to said element that movement of the rod in one direction is utilized to impart movement to the element; said mechanism comprising a cylinder coaxial with said rod; said cylinder having a head provided with an opening through which said rod extends; an annular outer piston fitting the cylinder, having an annular piston. area facing the head, and provided with an annular valve seat disposed adjacent to its inner periphery and facing the head; an inner piston having its piston area facing the head and having a peripheral edge providing a valve member for cooperation with said annular seat and being movable from the latter toward the head when the inner piston moves relatively to the outer piston toward the head; means providing for attachment of the inner piston to said rod; a first spring for resisting movement of the outer piston toward the second head; a second spring for resisting movement of the inner piston toward the second head; the scal of the second spring being greater than that of the first spring; a first cylinder abutment for limiting movement of the outer piston away from said head; a second cylinder abutment for limiting movement of the inner piston toward the head; said outer piston valve seat and said inner piston valve member cooperating to limit movement of the inner piston away from the head when the outer piston engages the first abutment and to limit movement of the outer piston toward the head when the inner piston engages the second cylinder abutment; the piston areas of the inner and outer pistons cooperating with the cylinder and its head to define a pressure chamber; said cylinder having a drain opening which is open to the spring space thereof in all positions of the pistons; and means including a passage for conducting to the pressure chamber fluid whose pressure may vary.

2. The combination as claimed in claim. 1 with a seat engaging the first and second springs and adjustable axially of the cylinder.

3. The combination with an element to be moved, of mechanism including a rod having a range of axial movement and so disposed in relation to said element that movement of the rod in one direction is utilized to impart movement to the element; said mechanism comprising a cylinder coaxial with said rod; said cylinder having a head provided with an opening through which said rod extends; an annular outer piston fitting the cylinder, having an annular piston area facing the first head, and provided with an annular valve seat disposed adjacent to its inner periphery and facing toward the head; an inner piston having its piston area facing the head and having a peripheral edge providing a valve member for cooperation with said annular seat and being movable away from the latter toward the head when the inner piston moves relatively to the outer piston toward the head; means providing for attachment of the inner piston to said rod; a first helical spring having one end engaging the outer piston and serving to resist movement of the latter toward the second head; a second helical spring disposed within the first spring and having one end engaging the inner piston to resist movement of thelatter toward the second head; the scale of the second spring being greater than that of the first spring; a seat engaging the ends of the first and second springs remote from the outer and inner pistons; means for adjusting the seat axially of the cylinder; a first cylinder abutment for limiting movement of the outer piston away from the head; a, second cylinder abutment for limiting movement of the inner piston toward the head; said outer piston annular valve seat and said inner piston valve member cooperating to limit movement of the inner piston away from the head when the outer piston engages the first abutment and to limit movement of the outer piston toward the head when the inner piston engages the second cylinder abutment; the piston areas of the inner and outer pistons cooperating with the cylinder and its head to define a pressure chamber; said cylinder having a drain opening which is open to the spring space thereof in all positions of the pistons; and means including a passage for conducting to the pressure chamber fluid whose pressure may vary.

4. The combination with an element to be moved, of mechanism including a rod having a range of axial movement and so disposed in relation to said element that movement of the rod in one direction is utilized to impart movement to the element; said mechanism comprising a cylinder coaxial with said rod; said cylinder having a head provided with an opening through which said rod extends; said cylinder having bores of larger and smaller diameter joined by a radial abutment face; said bore of smaller diameter extending from the radial abutment face away from said head and said bore of larger diameter extending from the abutment face toward the head; an outer annular piston fitting the bore of smaller diameter, having an annular piston area facing the head, provided with an annular valve seat at its inner periphery and facing said head, and having a flange disposed in the bore of larger diameter and the flange being provided with a radial face for engagement with said abutment face; an inner piston having its piston area facing the head and having a peripheral edge providing a valve member for cooperation with said annular valve seat and being movable away from the latter toward the head when the inner piston moves relatively to the outer piston toward the head; means providing for attachment of the inner piston to said rod; a first spring for resisting movement of the outer piston away from the head; a second spring for resisting movement of the inner piston away from the head; the scale of the second spring being greater than that of the first spring; means for limiting movements of the outer annular piston away from the head and of the inner piston toward the head and comprising said radial faces of said abutment and of said flange and an abutment carried by the cylinder for contact by the inner piston; said outer piston annular valve seat and said inner piston valve member cooperating to limit movement of the inner piston away from the head when the radial face of the flange of the outer piston engages the radial abutment face of the cylinder and to limit movement of the outer piston toward the head when the inner piston engages its abutment carried by the cylinder; the piston areas of the inner and outer pistons cooperating with the cylinder and its head to define a pressure chamber; said cylinder having a drain opening which is open to the spring space thereof in all positions of the pis tons; and means including a passage for conducting to the pressure chamber fluid whose pressure may vary.

5. The combination as claimed in claim 4 with common means for adjusting the first and second springs to vary the forces exerted therebyon the outer and inner pistons. I

6, The combination with an element to b moved, of mechanism including a rod having a range of axial movement and so disposed in relation to said element that the outer portion of movement of the rod in one direction is utilized to impart movement to the element; said mechanism comprising a cylinder coaxial with said rod; said cylinder having first and second heads with the first head located nearer to the element than the second head and the first head having an opening through which said rod extends; said cylinder having bores of larger and smaller diameter joined by a radial abutment face; said bore of smaller diameter extending from the abutment face toward the second head and said bore of larger diameter extending from the abutment face toward the first head; an outer annular piston fitting the bore of smaller diameter, having an annular piston area facing the first head, provided with an annular valve seat at its inner periphery and facing said first head, and having a flange disposed in the bore of larger diameter and provided with a radial face for engagement with said abutment face; an inner piston having its piston area facing the first head and having a peripheral edge providing a valve member for cooperation with said annular valve seat and being movable away from the latter toward the first head when the inner piston moves relatively to the outer piston toward the first head; means providing for attachment of the inner piston to said rod; a spring seat in the cylinder and located adjacent to said second head; a first helical spring interposed between the outer annular piston and the spring seat; a second helical spring interposed between the inner piston and the spring seat; means carried by the second head for adjusting the spring seat axially of the cylinder; the scale of the second spring being larger than that of the first spring; means for limiting movements of the outer annular piston toward the second head and the inner piston toward the first head and comprising said radial first head to define a pressure chamber; said cylinder having a drain opening which is open to the spring space thereof in all positions of the pistons; and means including a passage for conducting fluid whose pressure may vary to the pressure chamber.

MANIOUS GOTTLIEB.