US 2966929 A
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Description (OCR text may contain errors)
Jan. 3, 1961 2,966,929
D. 5. BROWN STOP MEANS FOR LIMITING THE COMPRESSION AND EXPANSION OF A BELLOWS MEMBER Filed Sept. 10, 1958 DANIEL 5. BROWN INVENTOR.
BYMWM i t h United States Patent STOP MEANS FOR LIMITING THE COMPRESSION AND EXPANSION OF A BELLOWS MEMBER Daniel S. Brown, Norwood, Mass., assignor to Worthington Corporation, Harrison, N.J., a corporation of Delaware Filed Sept. 10, 1958, Ser. No. 760,115
3 Claims. (Cl. 137-781) This invention relates to a detachable sealed bellows member and more particularly to stop means for precluding the over expansion and over compression of the bellows members.
The stop means contemplated by this invention is particularly applicable to sealed bellows which are operable in a transmitter to compensate for ambient changes.
Some transmitter applications require the repositioning of the transmitter range. As a consequence, certain of the elements of the controller must be replaced. One such element is the above described sealed bellows member which is removably connected in the transmitter and operable therein to compensate for changes in ambient conditions.
It is evident then that such bellows members are either separately shipped to the user or separately stored by him, for connection in the transmitter in the event that a range change is necessitated.
Accordingly, this invention contemplates the preclusion of damage to the bellows during the separate storage or shipment thereof which damage may cause a significant upset in the transmitter action.
It is an object of this invention to provide a bellows member with means for precluding damage to the sensitive portions thereof during the shipment, storage or assembly of the bellows member.
It is another object of this invention to provide a bellows member with means for limiting the compression and expansion thereof which is simple in construction and effective in the contemplated function.
With these and other objects in view, as may appear from the accompanying specification, the invention consists of various features of construction and combination of parts, which will be first described in connection with the accompanying drawings, showing by way of example, the novel stop means associated with a bellows member operative in a transmitter, and the features forming the invention will be specifically pointed out in the claims.
In the drawings:
Figure l is a side elevation partly in section of a transmitter including a bellows member embodying the present invention.
Figure 2 is a vertical section of the bellows member embodying the present invention.
Figure 3 is an exploded view of the bellows member.
Figure 4 is a side view of the upper body member of the bellows.
Figure 5 is a bottom view of the upper body member.
Figure 6 is a top view of the lower body member of the bellows.
Referring now more particularly to the drawings, a transmitter generally designated 1 is shown and includes a frame 2 which provides a base for mounting the subassemblies of the transmitter 1 thereon.
A measuring element 3 is mounted on the frame and adapted to sense changes in a process in the usual manner and transmit these process variations to a beam 4 pivotably mounted to the frame 2 and in pressure varying relation with a nozzle 5 by means such as flexure bearings 6.
The usual pressure variations of the fluid flowing through the nozzle 5, resulting from beam movement to and from the nozzle outlet, signals means (not shown) through a pilot (not shown) to return the process to'the desired condition.
The usual feedback means 7 is associated with the beam and pneumatically connected to an output line of the pilot (not shown) whereby the increased output pressure produces a restoring force on the beam opposing that of the measuring element 3.
In order to eliminate the effects that changes in ambient conditions have on the transmitter, bellows member 8 is removably mounted thereon in operative association with the beam 4.
The bellows member 8 comprises plural body members 9 and 10 movably joined in superposed axial rela' tionship by a flexible means 11 which is connected to upper body member 9 at its lower outer periphery 12 and to the lower body member 10 at its inner outer periphery 13. Means such as threads 14 and threaded hole 15 are provided for body members 9 and 10 for mounting same in operable position on frame 2 and beam 4. In order to retain the ideal sensing action regardless of changes in ambient conditions, a gas such as nitrogen is introduced into the sealed bellows member through spout 16 which communicates with the inner portions thereof through drilled hole 17.
It is evident that ambient changes will signal the bellows member 8 to actuate the beam 4 to retain the predetermined sensing action of the transmitter.
As was indicated hereinbefore, bellows sensitivity is often damaged by vibrations, jarring blows and wide changes in ambient conditions.
Stop post 18 mounted in frame 2 in the usual manner operates to limit the movement of beam 4 and functions to preclude damage to the sensitive elements of the instrument.
However, bellows member 14 and other sensitive elements of the transmitter may be replaced as was discussed above during a readjustment of the range span thereof.
Accordingly, coacting stop means 19 and 20 are incorporated in the bellows member 8 to provide means for precluding damage to the bellows during the separate shipment or storage thereof.
Stop means 19 comprises a drilled hole '21 in the upper body member 9 and means coacting with the hole 21 taking the form of a threaded extension is provided for the lower body member 10 whereby over expansion of the bellows is absolutely eliminated. The stop means 19 in body member 9 comprises the hole 21 through the lower portion of body member 9 and includes a threaded hole 22 opening into hole 21 which is in axial alignment with the threaded extension 23 and adapted to threadably receive the foregoing extension means 23.
Arrangement and disposition of stop means 19 in the form of a hole 21 and a threadable extension threadably received by the hole 21 provides oppositely disposed end faces '24 and 25 on the adjacent ends of the upper and lower body members 9 and 10 which function as stop means to limit the movement of the bellows member in compression.
The cocking tendency of the bellows that results during an abnormal compression is substantially eliminated with the provision of wide end faces to limit the over compression of the bellows.
In assembly the flexible member is mounted in position. The extension 23 is threaded through means 22 until it disengages and is accordingly operable to limit the expansion of the bellows. At the same time the end faces 24 and 25 are positioned to limit the compression of the bellows an abutment thereof. The flexible member is then sealably connected to the upper and lower body members as was hereinabove described and the gas is introduced into the bellows through spout 16 and sealed therein by the usual method.
As many embodiments may be made in the above invention and as many changes may be made in the embodiment above described, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative only and not in a limiting sense.
What is claimed is:
1. A sealed bellows means comprising plural body members, flexible means movably joining said body members in superposed axial relationship, a first bore in one of said body members, a second bore in the last mentioned body member and communicating with said first bore, threaded means for the second bore, an extension von the other body member and having threaded means thereon whereby said extension is passed through said second bore and movably received by the first bore to limit the expansion of the bellows means, and oppositely disposed faces on each of the adjacent ends of said body members and adapted to limit the compression of said bellows member.
2. Stop means for limiting the expansion and compression of a sealed bellows member having plural body members, flexible means for movably joining said body members in superposed axial relationship, said stop means comprising a first bore in one of said body members, a second bore in the last mentioned body member and communicating with said first bore, threaded means for the second bore, an extension on the other body member and having threaded means thereon whereby said extension is passed through said second bore and movably received by the first bore to limit the expansion of the bellows means, and oppositely disposed faces of substantially same dimension on each of the adjacent ends of said body members and adapted to limit the compression of said bellows member.
3. A sealed bellows for detachable connection to a control instrument, said bellows comprising plural body members, each of said body members including an outer portion and a necked-down inner portion having the same dimensions and of lesser dimension than the outer portions of the body members, a flexible member connected to the outer portions of each of the body members to movably join said body members in superposed parallel axial relation whereby the two faces formed by the inner portions of the body members coact to limit the over-compression of said bellows, a first bore in the necked-down portion of one of said body members, a second bore in the last-mentioned body member and the centerline thereof being normal to the centerline of the first bore, threaded means for the second bore, an extension on the other body member having threaded means thereon whereby said extention is passed through said second bore and movably received by the first bore to limit the over-expansion of said bellows.
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