CA2054988A1 - Indicating device - Google Patents
Indicating deviceInfo
- Publication number
- CA2054988A1 CA2054988A1 CA002054988A CA2054988A CA2054988A1 CA 2054988 A1 CA2054988 A1 CA 2054988A1 CA 002054988 A CA002054988 A CA 002054988A CA 2054988 A CA2054988 A CA 2054988A CA 2054988 A1 CA2054988 A1 CA 2054988A1
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- Prior art keywords
- cylinder
- piston
- switch
- slave
- indicating device
- Prior art date
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Abstract
ABSTRACT OF THE DISCLOSURE An indicating device for repeatedly indicating variation in the load on a part such as a polish rod of a pump is disclosed. The indicating device includes an indicator for providing an indication when current flows through the indicator, a switch for moving between an opened and a closed position and for permitting current to flow through the indicator when the switch is in one of the open and closed positions, and reciprocating moving means for reciprocatingly moving in response to reciprocating movement of the part and for moving the switch to the one of the open and closed positions once during each cycle of the reciprocating movement of the reciprocating moving means. The indicator thus provides the indication once during each cycle of the reciprocating movement of the part and thus repeatedly indicates reciprocating movement of the part.
Description
~IE~D O~ THE INV~TIO~
The present invention relates to devices useful for indicating variations in load on reciprocatingly moving parts.
More particularly, the present invention relates to indicating devices for indica~ing variations in polish rod loads.
BACR~ROUND AND ~UNMaRY OF THB INV~TIO~
Several types of devices which are adapted to provide indications of the performance of reciprocatingly moving parts are known in the prior art. For example, U.S. Patent No.
4,509,901 to McTamaney et al. discloses an apparatus for detecting probl~ms in sucker-rod well pumps, which includes a first transducer -which is located between an upper end of a sucker-rod string and a lower end of a cable section. U.S.
Patent No. 3,343,409 to Gibbs discloses a method of determining sucker rod performance in which a strain-gauge load cell is connected to a polished rod to measure the polished rod load.
Also, U.S. ~atent No. 4,363,60~ to Mills discloses an apparatus which generates an electrical signal which is proportional to the tension in a bridle which supports a string of a sucker rod. The apparatus includes a load cell between two arms which are attached to two bridle cables and which place the load cell in compression, so that the load cell generates an electrical signal proportional to the Porce needed to spring the cables apart from each other. The apparatuses of the above-mentioned patents each have the disadvantage, however, that they involve relatively complex electrical measurement and/or computation, and thus tend to be relatively complex and expensive to manufacture.
Other devices are known in the prior art which provide continuous indications of a weight on a drill bit. ~or example, U.S. Patent NOr 2,703,908 to Sel~os et al. discloses a weight-on-bit indicating apparatus which includes a weight responsive device attached to a line o~ a well drilling rig. The weight responsive device generates a pressure signal to three diaphragms which are pressure-balanced such that the weight on a bit o~ the well drilling rig registers on a gauge. ~lso, U.S. Patent No~
The present invention relates to devices useful for indicating variations in load on reciprocatingly moving parts.
More particularly, the present invention relates to indicating devices for indica~ing variations in polish rod loads.
BACR~ROUND AND ~UNMaRY OF THB INV~TIO~
Several types of devices which are adapted to provide indications of the performance of reciprocatingly moving parts are known in the prior art. For example, U.S. Patent No.
4,509,901 to McTamaney et al. discloses an apparatus for detecting probl~ms in sucker-rod well pumps, which includes a first transducer -which is located between an upper end of a sucker-rod string and a lower end of a cable section. U.S.
Patent No. 3,343,409 to Gibbs discloses a method of determining sucker rod performance in which a strain-gauge load cell is connected to a polished rod to measure the polished rod load.
Also, U.S. ~atent No. 4,363,60~ to Mills discloses an apparatus which generates an electrical signal which is proportional to the tension in a bridle which supports a string of a sucker rod. The apparatus includes a load cell between two arms which are attached to two bridle cables and which place the load cell in compression, so that the load cell generates an electrical signal proportional to the Porce needed to spring the cables apart from each other. The apparatuses of the above-mentioned patents each have the disadvantage, however, that they involve relatively complex electrical measurement and/or computation, and thus tend to be relatively complex and expensive to manufacture.
Other devices are known in the prior art which provide continuous indications of a weight on a drill bit. ~or example, U.S. Patent NOr 2,703,908 to Sel~os et al. discloses a weight-on-bit indicating apparatus which includes a weight responsive device attached to a line o~ a well drilling rig. The weight responsive device generates a pressure signal to three diaphragms which are pressure-balanced such that the weight on a bit o~ the well drilling rig registers on a gauge. ~lso, U.S. Patent No~
2,696,111 to Conner discloses a drill string weight indicating apparatus which includes a roller to which force is applied hy a drill string, a diaphragm which is connected $o the roller and .~ , ,.
~2--which closes a chamber, and a pressure gauge connected to the chamber to indicate the load on the drill string based on the pressure in the chamber. These devices have the disadvantage, however, that they are designed for use with a drill string which moves slowly past the devices in one direction only. Thus these devices are of little use in providing an indication of the variation in load on a reciprocatingly moving part.
One device is known in the prior art which provides an indication of the pressure in an apparatus, wherein the apparatus includes a reciprocatinyly moving part. U.S. Patent No.
4,417,236 to Hunq discloses an overload detecting device for a hydraulic jack which includes a pressure sensitive switch member having a piston-like member in a housing. The piston-like member communicates with a duct o the hydraulic jack and is biased in one direction by a spring. If the pressure in the duct rises above a predetermined valuel the pressure overcomes the bias of the spring, and the piston-like member contacts a spring plate to set off an alarm. One of the disadvantages of this device, however, is that the device only actuates the alarm when the pressure in the hydraulic jack rises above a certain level.
Thus, this device is of little use in providing a repeated indication of reciprocating movement of a part such as a polish rod~
In view of the above, it is an object of the present invention to provide an improved device for indicating variations in load on a reciprocatingly moving part such as a polish rod.
A further object of the present invention is to provide an indicating device which is relatively simple and inexpensive to manufacture.
It is a ~urther object of the present invention to provide a simple, reliable device which will provide an indication of load variation once during each cycle of the reciprocably moving part.
It is a further object of the present invention to provide an indicating device which re~uires relatively minimal technical sophistication to monitor.
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Yet another object of the present invention is to provide an indicating device which is subjected to the full load on a reciprocating moving par~ to more accurately monitor the moving part.
5It is a further object of the present invention to provide an indicating device which provides continuous monitoring of a reciprocably moving part.
It i~ a further object of the present invention to provide an indicating device which is of rugged construction and thus 10resistant to damaye.
It is a further object of the present invention to provide an indicating device which is simple to repair when necessary.
A further object of the present invention is to provide an indicating device which is adjusta~le to compensate for wear on 15the device and ~or variations in a reciprocating movement of a part.
The above objects as well as other objects not specifically enumerated are accomplished by an indicating device for indicating variations in a load on a reciprocatingly moving part 20in accordance with the present invention. The indicating device of the present invenkion includes reciprocating moving means for reciprocatingly moving in response to the variations in the load, indicating means for providing an indication, and switch means for switching between an open state and a closed state and for 25causing current to flow through the indicating means when the switch means is in one of the open and closed states, wherein the reciprocating moving means causes ~he switch means to switch to the one of the open and closed states once during each cycle of the reciprocatiny movement of the reciprocating moving means.
30The objects of the present invention are also accomplished by a polish rod load indicating device which includes a master piStOll and cylinder enclosing a fluid therebetween, wherein the master piston and cylinder are connectable to the polish rod such that one of the master piston and cylinder moves cyclically with 35respect to the other of the master piston and cylinder, a slave piston arld cylinder enclosing a fluid therebetween which is in communisation with the fluid enclos~d by the master piston and ,. ~
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', ' .' ~,, -4- ~ ~ ~ ~9 cylindPr, wherein the cyclical movement of the one of the master piston and cylinder produces a cyclically varying pressure in the fluids and wherein the cyclically varying pressure in the fluids causes one of the slave piston and cylinder to move cyclically S relative to the other of ~he slave piston and cylinder, an indicator/ and a switch, wherein the indicator produces a polish rod load indication signal in respons~ to operation of the switch, and wherein the cyclically moving one of the slave piston and cylinder operates the switch to cause the indicator to produce the polish rod load indication signal once during each cycle of the cyclical movement of the cyclically moving one of the slave piston and cylinder.
: The ob~ects of the present invention are further accomplished by a polish rod load indicating device for indicating variation in a polish rod load, which includes a toroidally-shaped master piston, a toroidally-shaped master cylinder cooperating with the master piston to enclose a fluid, the master piston and cylinder ~eing connected to a portion of the pump, a slave piston and cylinder enclosing a fluid which is : 20 in fluid communication with the fluid enclosed by the master piston and cylinder, wherein the slave piston includes a flange portion~ is movable between extended and retracted positions within the slave cylinder, and is spring biased towards the retracted position, a switch, wherein the switch is movable between an open position and a closed position and ls spring biased towards the open position, and an indicator, the indicator producing an indication when current flows therethrough, wherein the master piston is cyclically moveable in response to cyclical movement of the polish rod to produce a cyclically varying : 30 pressure in the fluids, and wherein the cyclically varying pressure causes the slave piston to move cyclically between the extended and retracted positions such that the flange portion of the slave piston moves the switch to the closed position when the slave piston is in the retracted position, closing of the switch causing current to flow through ~he in~icator so that the indicator provides the indication once during each cycle of the ~.
cyclical movement of the ma~ter piston to indicate variation in the polish rod load.
BRIEF DE~CRIPTIOlN OF TIIB CIRI~WING~
The preferred embodim~nts of the present invention will be described in greater detail with reference to the accompanying drawings, wherein like members bPar like reference numerals and wherein:
Fig~ 1 is a partially cutaway side view of the indicating device of the present invention; and Fig~ 2 is a diagram of an electrical circuit of the indicating device o~ Fig. 1.
DE~I!AXLE:l~ DE~: ~Ill?TIO~a OF ~13 PREFE~ R13D E:~BOD~ T
With r~ference to Figs. 1 and 2, an indicating device 10 in accordance with the present invention includes a master piston and cylinder arrangement 12, a slave piston and cylinder arrangement 14, and an indicating circuit arrangement 16 which includes an indicating circuit 17, as is explained further hereinbelow.
As is seen in Fi~. 1, the mastex piston and cylinder arrangement 12 includes a master pi5ton 20 and a master cylinder 2Z. The master piston 20 and the master cylinder 22 are shaped as right cylindrical toroids, and are especially adapted to extend around a polish rod 1 of a conventional pump between a polish rod clamp 2 and a bridle 3 o~ the pump, since the master piston 20 has a hole 24 therethrough and the master cylinder 22 has a hole 33 therethrough through which the polish rod 1 extends. The polish rod 1, as can be seen in Fig. 1, is tightly clamped by the polish rod clamp 2, and the polish rod clamp 2 : rests on the ma~ter piston 200 The bridle 3 is pulled upwardly by portions of the pump which are not shown, and the master cylinder 22 rests on the bridle 3. Accordingly, as the bridle 3 is pulled upwardly, it also pulls the master cylinder 22, the master piston 20, the polish rod clamp 2, and the polish rod 1 upwardly, so that the master pi5ton and cylinder bPar the entire load on the polish rod 1.
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The master piston 20 includes a pair of 0-rings 26,2~3 which extend along outer and inner surfaces 30,32 of the master piston 20, respectively, and whose function will be described hereinbelow. The master cylinder 22 is larger than the master piston 20, and includes a right cylindrical, toroidally-shaped chamber 34 which extends downwardly therein from an upper surface 36 of th~ master cylinder 22. The chamber 34 i5 formed such that it is slightly larger than the master piston 20, so that the master piston 20 is slidably received in the chamber 34 with the 0-rings ~6,28 providing sealing contact between the master piston 22 and outer and inner walls 40,42, respectively, of the chamber 34.
Accordingly, the master piston 20 and the master cylinder 22 together enclose a fluid-tight space 44 which i5 formQd from a lower portion of the chamber 34 and which is normally filled with a fluid. In addition, the master cylinder 22 includes a passageway 46 which communicates the space 44 with a threaded opening 48 in an outer surface 50 of the master cylinder 22.
As is seen in Fig. 1, the slave piston and cylinder arrangement 14 includes a slave cylinder 60 and a slave piston 62. The slave cylinder 60 is ~ormed as an elongated, hollow cylinder which is open at both ends, and includes a threaded extension 64 extending from a first end ~5 thereof. The threaded extension 64 is threadably engaged with the threaded opening 48 in the master cylinder 22, and a passageway 66 is formed through the threaded extension 6~ such that it communicates the passageway 46 with a space 70 in a chamber 68 in the slave cylinder 60. The slave cylinder 60 also includes an 0-ring 72 which is fitted on the first end 65 o~ the slave cylinder 60 to prevent fluid leakage between the master cylinder 22 and the slave cylinder 60.
The chamber 68 of the slave cylinder 60 includes a first chamber portion 74 which has a smaller diameter, and a second chamber portion 76 which has a larger diameter. As can be seen from Fig. 1, a wall 78 is forme~ in a transition portion of the chamber 68 between the first and second chamber portions 74,76, and the space 70 in the chamber 68 is formed by a portion of the . .
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first, smaller diameter chamber portion 74. The second, larger diameter chamber portion 76 includes an internally threaded portion 80 whi~h opens through a second end 82 of the slave cylinder 60 which is opposite the first end 65, and an elongated, hollow cylindrical plug 84 having external threads 86 thereon is threaded into the internally threaded portion 80 of the slave cylinder 60~ The function and purpose of the plug 84 will be explained hereinbelow.
The slave piston 62 is an elongated member which fits slidably within the slave cylinder 60, and it includes a piston member 90 and an elongated rod 92. ~he piston member 90 includes a first portion 94 which has a diam~ter which is slightly smaller than the diameter of the first chamber portion 74 of the slave cylinder 60l and a second portion 96 which has a diameter which is slightly smaller than the diameter of the second chamber portion 76 of the slave cylinder 60, but which is larger than the diameter of the ~irst chamber portion 740 The piston member 90 also includes sealing means therearound to prevent leakage from the slave piston and cylinder arrangement. For illustration purposes, the sealing means is shown as a pair of 0-rings 98,100 which are fitted around an outer surface 102 of the piston member 90, but other sealing means such as a cup-type packing could just as easily be used. Accordingly, the first portion 94 of the piston member 90 fits slidably and fluid-tightly within the first chamber portion 74 of-the slave cylinder 60 such that the piston member 90 and the slave cylinder 60 form the fluid-tight space 70, and the second portion 96 of the piston member 90 ~its slidably within the second chamber portion 76 of the slave cylinder 60. Enclosed in the space 70 is a fluid which is in fluid communication wikh the ~luid enclos~d by the master piston 20 and the mast~r cylinder 22.
The piston member 90 also includes a threaded hole 104 which extends through the secsnd portion 96 of the piston member 90, and the elongated rod 92 is attached to the piston member 90 by thr~aded engagement of a fir~t threaded end 106 of the elongated rod 92 with the threaded hole 104. As is shown in Fig. 1, the elongated rod 92 extends away from the pi~ton member 90 through `:
a hole in the plug 84 to a location outside the slave cylinder 60, and includes a second threaded end 108 onto which a threaded adjustmen~ member 110 having a ~lange portion 112 is threaded.
Also, a spring 114 is arranged in compression inside the second chamber portion 76 of the slave cylinder 60 between the plug 84 and the second portion 96 of the piston member 90, such that the slave piston 62 is spring biased toward the left in Fig. 1.
As is seen from Fig. 1, the indicating circuit arrangement 16 o~ the present invention includes a pair of mounts 120,122 which are welded ~o the outside of the slave cylinder 60, and which support a frame member 124 and ther~.by a circuit box 126.
On one end of the frame member 124 is mounted a switch box 128 which includes a set of first terminal~ 130, a second terminal 132, and a switch member 134 which is pivotally mounted to the switch box 128 and which is spring biased away from the second terminal 132. The switch member 134 and the second terminal 132 together form a contact switch. A wire 136 is connected to two of the first terminals 130, which wire runs into the circuit box 126. Cn the outside of the circuit bo~ 126 is mounted an LED
indicator 138.
As is ~een in Fig. 2, the second terminal 132, the switch member 134, and ~he ~ED indicator 138 all form part of an indicating circuit 17 of the present invention. ~s shown, the indicating circuit 17 is a simple circuit powered by two batteries 1~0 arranged in serie~, and includes a resistance 142 and the LED indicator 138 arranged in series. As is shown in Fig. ~, no current can flow through the indicating circuit 17 when the contact switch formed by the second terminal 132 and the switch member 134 is open. However, current will flow through the indicating circuit 17 and thus the LED indicator 138 will light when the sontact swi.tch is closed, i.e., when the switch member 134 contacts the second terminal 132 as shown in Fig~ 1.
With reference to Figs. 1 and 2, the operation o~ the indicating device 10 will now be explained. In use, the master piston 20 and the master cylinder 22 are held between the polish rod ~lamp 2 and the bridle 3 of a convsntional well pumpO The bridle 3 moves reciprocably in an up and down manner to pull up 2~
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the polish rod clamp 2, and thereby the polish rod 1, and then lower it repeatedly, and a cyclically varying force is thus applied to the master piston and cylinder arrangement which causes the master piston 20 to move reciprocally or cyclically with respect to the master cylinder 22. For example, with a pump stroke of approximately 6~ inches, a force of about 20,000 lbs.
is applied to the master piston and cylinder arranyement during an upstroke of the pump, while a force of only about 12,000 lbs.
is applied to the master piston and cylinder durin~ a downstroke of the pump.
Since the slave piston ~2 and the slave cylinder 60 enclose in the space 70 a fluid which is in fluid communication with the fluid enclosed by the master piston 20 and the master cylinder 22, a cyclically varying pressure is produced in both of the fluids as the master piston 20 moves reciprocally or cyclically relative to the master cylinder 22. Thus, the cycl.ically varying pressure in the fluids a~ts to cause the slave piston 62 to move reciprocally or cyclic~lly against the force of the spring 114, due to the force exerted on the piston member 90 by the fluids.
20 Th8 slave piston 62 therefore moves repeatedly between a retract d position wherein the second portion 96 o~ the piston member 90 is at its leftmost position in the chamber 68 as shown in Fig. 1 due to the force of the spring 114 acting between the plug 84 and the second portion 96, and an extended position wherein khe second portion 96 of the piston member 90 is at its rightmost position in the chamber 68 due to the force of the fluids enclosed by the master and slave piston and cylinder arrangements.
As the slave piston 62 moves cyclically or recipro~ably, the threaded adjustment member 110 moves rigidly with the slave pisto~ 62, and thus the flange portion 112 of the threaded adjustment memb~r 110 moves cyclically left-to-right and right-to-left in Fig. 1. The flange portion 112 of the threaded adjustment member llQ thus repeatedly moves the switch member 134 from a spring biased open position to a closed position seen in Fig. 1 where the switch member 134 contacts the second terminal 132, and then releases the switch member 134 to allow it to ., ~
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return to its spring biased open position. Thus, each time the ~lave piston 62 is brought into its retracted position, the contact switch of indicating circuit 17 is closed, and current flows through the indicating circuit 17 to light the LED
indicator 138.
As can be appreciated from Fig. 1, turning of the plug 84 relative to the slave cylinder 60 will result in ax.ial movement of the plug 84 relative to the slave cylinder 60~ due to the coaction of internally threaded portion 80 and external threads 86. Accordingly, the force of the spring 114 on the piston member 90 at aIIy given position of the piston member 90 can be varied by turning the plug 84, and thus the exact left-to-right location of the extended position of the slave piston 62 can be precisely set as follows. The plug 84 is first tightened until the spring 11~ is compressed and the second portion 96 of the piston member 90 abuts the wall 78. The threaded adjustment member 110 is then tightened until the flange portion 112 just closes the switch, iOe., until the switch member 134 just contacts the second terminal 132. The plug 84 is then backed out so that the spring 114 is less co-mpressed, but so that the spring 114 is still compressed enough to keep the switch closed. Load is then applied to the polish rod 1, and the plug 84 is adjusted until the ~orce sf spring 114 is just high enough to retain the second portion 96 against the wall 78 at the minimum lvad and thereby cause the switch to be closed. Consequently, at this setting of the plug and the spring force the variations in the load will cause the switch to be repeatedly turned on and off.
Thus, the extended position of the slav~ piston 62 is set during this final adjustment of the plug 84.
The ability to thus adjust the extended position of th~
slave plston 62 allows a user to set up the indicating device such that the flange portion 112 of the threaded adjustment member 110 just closes the contact switch when the slave piston 62 i8 in the retracted positionO The indicating device can therefore be set up such that the ~ED indicator 138 lights just once during each cycle of a reciproca~ingly moving part such as a polish rod of a pump~ and the indicating device is therefore .
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ll--able to prvduce an indication of the variation in the polish rod load. Adjustment of the point at which the contact switch is closed can also be accomp~ished by turning of the threaded adjustment washer 110 on the rod 92, which varies the distance between the piston member 90 and the flange portion 112.
The adjustment features of the present invention allow a single indicating device to be used with any of a wide range o~
wells, both deep and shallow, since the indicating device can be adjusted to indicate a wide variation of loads. The indicating device can also use the adjustment features to compensate for changes in elasticity of the spring 114, and small losses of fluid in the master and slave piston and cylinder arrangements.
Accordingly, the adjustment features allow the indicating device o~ the present invention to be used ~or long periods of time without repair or replacement.
The indication of load variation in a reciprocatingly moving part such as a polish rod of a pump, which is provided by the indicating device of the present invention, is a simple and reliable indication which can readily be monitored by an operator who may not have a high level of technological expertise. For example, when the indicating device of the present invention is being used with ~ pump which i~ experiencing a desired load variation, an operator will see a simple cyclical on/off pattern o~ flashing from the LED indicator of the indicating device. As long as the on/off pattern of flashing continue~, and continues at the same frequency, the operator is given a good indication that the load is varying as desired. If the on/off pattern stops, i.e., if thP indicator stays on or stays off, or if the frequency of flashing of the LED indicator changes, the operator knows that the pump has completely stopped operating, that the connection between the polish rod and the bridle has somehow failed, that a rod break has occurred and that the polish rod is no longer supporting a heavy weight, or that some other abnormal condition of the pump has occurred. With a little experience with the indicating device, an operator can quickly recognize the condition which a particular flashing pattern indicates. Thus, ' .
~~2-the indicating device of the present invention is extremely simple to monitor.
Additionally, since the indicating device is simple and rugged in construction, it is subject to only infrequent break downs, and, when it does ~reak down, it is relatively simple to repair, since it contains no complex electronics~
It is to be appreciated that the advantages of the present invention can be obtained through the use of any of a number of fluids in the master and slave pistons and cylinders. For example, hydraulic fluid, oil, air, or other fluids may be used.
Also, although the master and slave pistons and cylinders are shown in the drawings as being made of metalr they could also be advantageously made of any number of materials, such as plastic, ceramic, or combinations thereof. It is also to be understood that the indicating circuit arrangement may be mounted separately from th~ slave cylinder if desired, and that the slave piston and cylinder may be separate from the main piston and cylinder with, ~or example, a hose keeping the main and slave piston and cylinders in fluid communication.
Indicating circuit arrangements which are different from the one disclosed may be used, and advantages of the present invention obtained therefromO For example, a circuit which includes a transistor may be used in the present inventiQn, such that closing of the contact switch causes the transistor to cut the flow of curr0nt to the LED indicator, and therefore such that the LED indicator normally provides a lighted indication, and is not lit only when the contact switch is closed. Also, the contact switch of the present invention may be replaced with another switch such as a magnetic switch, and the LED indicator may be replaced with another indicator such as a buzzer, a bell, or a whistle, and advantages obtained therefrom. The indicating circuit could also be completely replaced by a mechanical noisemaker which is activated once during each cycle of the slave piston. Also, the indicating circuit could be modified to allow graphic recording of the load variation on the polish rod, or to cause ~hut down of the power supply to the pump whan the load variation becomes irregular.
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At least some of the advantages of ~he present invention are also achievable if the slav~ piston and cy]inder arrangement is arranged in fluid communication with the master piston and cylinder arrangement through a passageway through the master piston~ Additionally, the slave piston may be held fixed to the master piston and cylinder arrangement, and the slave cylinder may be arranged movably, and some advantages obtained therefrom.
The principles, a preferred embodiment and the mode of operation of the present invention have been described in the foregoing specifica~ion. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiment disclosed. The embodiment is therefore to be regarded as illustrative rather than restrictive. Variations and changes may be made by others without deparrting from the spirit of the present invention. Accordingly, it is expr ssly intended that all such variations and changes which fall within the spirit and scope of the present invention as defined in the claims be embraced thereby.
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~2--which closes a chamber, and a pressure gauge connected to the chamber to indicate the load on the drill string based on the pressure in the chamber. These devices have the disadvantage, however, that they are designed for use with a drill string which moves slowly past the devices in one direction only. Thus these devices are of little use in providing an indication of the variation in load on a reciprocatingly moving part.
One device is known in the prior art which provides an indication of the pressure in an apparatus, wherein the apparatus includes a reciprocatinyly moving part. U.S. Patent No.
4,417,236 to Hunq discloses an overload detecting device for a hydraulic jack which includes a pressure sensitive switch member having a piston-like member in a housing. The piston-like member communicates with a duct o the hydraulic jack and is biased in one direction by a spring. If the pressure in the duct rises above a predetermined valuel the pressure overcomes the bias of the spring, and the piston-like member contacts a spring plate to set off an alarm. One of the disadvantages of this device, however, is that the device only actuates the alarm when the pressure in the hydraulic jack rises above a certain level.
Thus, this device is of little use in providing a repeated indication of reciprocating movement of a part such as a polish rod~
In view of the above, it is an object of the present invention to provide an improved device for indicating variations in load on a reciprocatingly moving part such as a polish rod.
A further object of the present invention is to provide an indicating device which is relatively simple and inexpensive to manufacture.
It is a ~urther object of the present invention to provide a simple, reliable device which will provide an indication of load variation once during each cycle of the reciprocably moving part.
It is a further object of the present invention to provide an indicating device which re~uires relatively minimal technical sophistication to monitor.
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Yet another object of the present invention is to provide an indicating device which is subjected to the full load on a reciprocating moving par~ to more accurately monitor the moving part.
5It is a further object of the present invention to provide an indicating device which provides continuous monitoring of a reciprocably moving part.
It i~ a further object of the present invention to provide an indicating device which is of rugged construction and thus 10resistant to damaye.
It is a further object of the present invention to provide an indicating device which is simple to repair when necessary.
A further object of the present invention is to provide an indicating device which is adjusta~le to compensate for wear on 15the device and ~or variations in a reciprocating movement of a part.
The above objects as well as other objects not specifically enumerated are accomplished by an indicating device for indicating variations in a load on a reciprocatingly moving part 20in accordance with the present invention. The indicating device of the present invenkion includes reciprocating moving means for reciprocatingly moving in response to the variations in the load, indicating means for providing an indication, and switch means for switching between an open state and a closed state and for 25causing current to flow through the indicating means when the switch means is in one of the open and closed states, wherein the reciprocating moving means causes ~he switch means to switch to the one of the open and closed states once during each cycle of the reciprocatiny movement of the reciprocating moving means.
30The objects of the present invention are also accomplished by a polish rod load indicating device which includes a master piStOll and cylinder enclosing a fluid therebetween, wherein the master piston and cylinder are connectable to the polish rod such that one of the master piston and cylinder moves cyclically with 35respect to the other of the master piston and cylinder, a slave piston arld cylinder enclosing a fluid therebetween which is in communisation with the fluid enclos~d by the master piston and ,. ~
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', ' .' ~,, -4- ~ ~ ~ ~9 cylindPr, wherein the cyclical movement of the one of the master piston and cylinder produces a cyclically varying pressure in the fluids and wherein the cyclically varying pressure in the fluids causes one of the slave piston and cylinder to move cyclically S relative to the other of ~he slave piston and cylinder, an indicator/ and a switch, wherein the indicator produces a polish rod load indication signal in respons~ to operation of the switch, and wherein the cyclically moving one of the slave piston and cylinder operates the switch to cause the indicator to produce the polish rod load indication signal once during each cycle of the cyclical movement of the cyclically moving one of the slave piston and cylinder.
: The ob~ects of the present invention are further accomplished by a polish rod load indicating device for indicating variation in a polish rod load, which includes a toroidally-shaped master piston, a toroidally-shaped master cylinder cooperating with the master piston to enclose a fluid, the master piston and cylinder ~eing connected to a portion of the pump, a slave piston and cylinder enclosing a fluid which is : 20 in fluid communication with the fluid enclosed by the master piston and cylinder, wherein the slave piston includes a flange portion~ is movable between extended and retracted positions within the slave cylinder, and is spring biased towards the retracted position, a switch, wherein the switch is movable between an open position and a closed position and ls spring biased towards the open position, and an indicator, the indicator producing an indication when current flows therethrough, wherein the master piston is cyclically moveable in response to cyclical movement of the polish rod to produce a cyclically varying : 30 pressure in the fluids, and wherein the cyclically varying pressure causes the slave piston to move cyclically between the extended and retracted positions such that the flange portion of the slave piston moves the switch to the closed position when the slave piston is in the retracted position, closing of the switch causing current to flow through ~he in~icator so that the indicator provides the indication once during each cycle of the ~.
cyclical movement of the ma~ter piston to indicate variation in the polish rod load.
BRIEF DE~CRIPTIOlN OF TIIB CIRI~WING~
The preferred embodim~nts of the present invention will be described in greater detail with reference to the accompanying drawings, wherein like members bPar like reference numerals and wherein:
Fig~ 1 is a partially cutaway side view of the indicating device of the present invention; and Fig~ 2 is a diagram of an electrical circuit of the indicating device o~ Fig. 1.
DE~I!AXLE:l~ DE~: ~Ill?TIO~a OF ~13 PREFE~ R13D E:~BOD~ T
With r~ference to Figs. 1 and 2, an indicating device 10 in accordance with the present invention includes a master piston and cylinder arrangement 12, a slave piston and cylinder arrangement 14, and an indicating circuit arrangement 16 which includes an indicating circuit 17, as is explained further hereinbelow.
As is seen in Fi~. 1, the mastex piston and cylinder arrangement 12 includes a master pi5ton 20 and a master cylinder 2Z. The master piston 20 and the master cylinder 22 are shaped as right cylindrical toroids, and are especially adapted to extend around a polish rod 1 of a conventional pump between a polish rod clamp 2 and a bridle 3 o~ the pump, since the master piston 20 has a hole 24 therethrough and the master cylinder 22 has a hole 33 therethrough through which the polish rod 1 extends. The polish rod 1, as can be seen in Fig. 1, is tightly clamped by the polish rod clamp 2, and the polish rod clamp 2 : rests on the ma~ter piston 200 The bridle 3 is pulled upwardly by portions of the pump which are not shown, and the master cylinder 22 rests on the bridle 3. Accordingly, as the bridle 3 is pulled upwardly, it also pulls the master cylinder 22, the master piston 20, the polish rod clamp 2, and the polish rod 1 upwardly, so that the master pi5ton and cylinder bPar the entire load on the polish rod 1.
i : . .. .
, 9~
The master piston 20 includes a pair of 0-rings 26,2~3 which extend along outer and inner surfaces 30,32 of the master piston 20, respectively, and whose function will be described hereinbelow. The master cylinder 22 is larger than the master piston 20, and includes a right cylindrical, toroidally-shaped chamber 34 which extends downwardly therein from an upper surface 36 of th~ master cylinder 22. The chamber 34 i5 formed such that it is slightly larger than the master piston 20, so that the master piston 20 is slidably received in the chamber 34 with the 0-rings ~6,28 providing sealing contact between the master piston 22 and outer and inner walls 40,42, respectively, of the chamber 34.
Accordingly, the master piston 20 and the master cylinder 22 together enclose a fluid-tight space 44 which i5 formQd from a lower portion of the chamber 34 and which is normally filled with a fluid. In addition, the master cylinder 22 includes a passageway 46 which communicates the space 44 with a threaded opening 48 in an outer surface 50 of the master cylinder 22.
As is seen in Fig. 1, the slave piston and cylinder arrangement 14 includes a slave cylinder 60 and a slave piston 62. The slave cylinder 60 is ~ormed as an elongated, hollow cylinder which is open at both ends, and includes a threaded extension 64 extending from a first end ~5 thereof. The threaded extension 64 is threadably engaged with the threaded opening 48 in the master cylinder 22, and a passageway 66 is formed through the threaded extension 6~ such that it communicates the passageway 46 with a space 70 in a chamber 68 in the slave cylinder 60. The slave cylinder 60 also includes an 0-ring 72 which is fitted on the first end 65 o~ the slave cylinder 60 to prevent fluid leakage between the master cylinder 22 and the slave cylinder 60.
The chamber 68 of the slave cylinder 60 includes a first chamber portion 74 which has a smaller diameter, and a second chamber portion 76 which has a larger diameter. As can be seen from Fig. 1, a wall 78 is forme~ in a transition portion of the chamber 68 between the first and second chamber portions 74,76, and the space 70 in the chamber 68 is formed by a portion of the . .
~ .
:
~::
-7- .
first, smaller diameter chamber portion 74. The second, larger diameter chamber portion 76 includes an internally threaded portion 80 whi~h opens through a second end 82 of the slave cylinder 60 which is opposite the first end 65, and an elongated, hollow cylindrical plug 84 having external threads 86 thereon is threaded into the internally threaded portion 80 of the slave cylinder 60~ The function and purpose of the plug 84 will be explained hereinbelow.
The slave piston 62 is an elongated member which fits slidably within the slave cylinder 60, and it includes a piston member 90 and an elongated rod 92. ~he piston member 90 includes a first portion 94 which has a diam~ter which is slightly smaller than the diameter of the first chamber portion 74 of the slave cylinder 60l and a second portion 96 which has a diameter which is slightly smaller than the diameter of the second chamber portion 76 of the slave cylinder 60, but which is larger than the diameter of the ~irst chamber portion 740 The piston member 90 also includes sealing means therearound to prevent leakage from the slave piston and cylinder arrangement. For illustration purposes, the sealing means is shown as a pair of 0-rings 98,100 which are fitted around an outer surface 102 of the piston member 90, but other sealing means such as a cup-type packing could just as easily be used. Accordingly, the first portion 94 of the piston member 90 fits slidably and fluid-tightly within the first chamber portion 74 of-the slave cylinder 60 such that the piston member 90 and the slave cylinder 60 form the fluid-tight space 70, and the second portion 96 of the piston member 90 ~its slidably within the second chamber portion 76 of the slave cylinder 60. Enclosed in the space 70 is a fluid which is in fluid communication wikh the ~luid enclos~d by the master piston 20 and the mast~r cylinder 22.
The piston member 90 also includes a threaded hole 104 which extends through the secsnd portion 96 of the piston member 90, and the elongated rod 92 is attached to the piston member 90 by thr~aded engagement of a fir~t threaded end 106 of the elongated rod 92 with the threaded hole 104. As is shown in Fig. 1, the elongated rod 92 extends away from the pi~ton member 90 through `:
a hole in the plug 84 to a location outside the slave cylinder 60, and includes a second threaded end 108 onto which a threaded adjustmen~ member 110 having a ~lange portion 112 is threaded.
Also, a spring 114 is arranged in compression inside the second chamber portion 76 of the slave cylinder 60 between the plug 84 and the second portion 96 of the piston member 90, such that the slave piston 62 is spring biased toward the left in Fig. 1.
As is seen from Fig. 1, the indicating circuit arrangement 16 o~ the present invention includes a pair of mounts 120,122 which are welded ~o the outside of the slave cylinder 60, and which support a frame member 124 and ther~.by a circuit box 126.
On one end of the frame member 124 is mounted a switch box 128 which includes a set of first terminal~ 130, a second terminal 132, and a switch member 134 which is pivotally mounted to the switch box 128 and which is spring biased away from the second terminal 132. The switch member 134 and the second terminal 132 together form a contact switch. A wire 136 is connected to two of the first terminals 130, which wire runs into the circuit box 126. Cn the outside of the circuit bo~ 126 is mounted an LED
indicator 138.
As is ~een in Fig. 2, the second terminal 132, the switch member 134, and ~he ~ED indicator 138 all form part of an indicating circuit 17 of the present invention. ~s shown, the indicating circuit 17 is a simple circuit powered by two batteries 1~0 arranged in serie~, and includes a resistance 142 and the LED indicator 138 arranged in series. As is shown in Fig. ~, no current can flow through the indicating circuit 17 when the contact switch formed by the second terminal 132 and the switch member 134 is open. However, current will flow through the indicating circuit 17 and thus the LED indicator 138 will light when the sontact swi.tch is closed, i.e., when the switch member 134 contacts the second terminal 132 as shown in Fig~ 1.
With reference to Figs. 1 and 2, the operation o~ the indicating device 10 will now be explained. In use, the master piston 20 and the master cylinder 22 are held between the polish rod ~lamp 2 and the bridle 3 of a convsntional well pumpO The bridle 3 moves reciprocably in an up and down manner to pull up 2~
9 - ~
the polish rod clamp 2, and thereby the polish rod 1, and then lower it repeatedly, and a cyclically varying force is thus applied to the master piston and cylinder arrangement which causes the master piston 20 to move reciprocally or cyclically with respect to the master cylinder 22. For example, with a pump stroke of approximately 6~ inches, a force of about 20,000 lbs.
is applied to the master piston and cylinder arranyement during an upstroke of the pump, while a force of only about 12,000 lbs.
is applied to the master piston and cylinder durin~ a downstroke of the pump.
Since the slave piston ~2 and the slave cylinder 60 enclose in the space 70 a fluid which is in fluid communication with the fluid enclosed by the master piston 20 and the master cylinder 22, a cyclically varying pressure is produced in both of the fluids as the master piston 20 moves reciprocally or cyclically relative to the master cylinder 22. Thus, the cycl.ically varying pressure in the fluids a~ts to cause the slave piston 62 to move reciprocally or cyclic~lly against the force of the spring 114, due to the force exerted on the piston member 90 by the fluids.
20 Th8 slave piston 62 therefore moves repeatedly between a retract d position wherein the second portion 96 o~ the piston member 90 is at its leftmost position in the chamber 68 as shown in Fig. 1 due to the force of the spring 114 acting between the plug 84 and the second portion 96, and an extended position wherein khe second portion 96 of the piston member 90 is at its rightmost position in the chamber 68 due to the force of the fluids enclosed by the master and slave piston and cylinder arrangements.
As the slave piston 62 moves cyclically or recipro~ably, the threaded adjustment member 110 moves rigidly with the slave pisto~ 62, and thus the flange portion 112 of the threaded adjustment memb~r 110 moves cyclically left-to-right and right-to-left in Fig. 1. The flange portion 112 of the threaded adjustment member llQ thus repeatedly moves the switch member 134 from a spring biased open position to a closed position seen in Fig. 1 where the switch member 134 contacts the second terminal 132, and then releases the switch member 134 to allow it to ., ~
-, r~ ~
return to its spring biased open position. Thus, each time the ~lave piston 62 is brought into its retracted position, the contact switch of indicating circuit 17 is closed, and current flows through the indicating circuit 17 to light the LED
indicator 138.
As can be appreciated from Fig. 1, turning of the plug 84 relative to the slave cylinder 60 will result in ax.ial movement of the plug 84 relative to the slave cylinder 60~ due to the coaction of internally threaded portion 80 and external threads 86. Accordingly, the force of the spring 114 on the piston member 90 at aIIy given position of the piston member 90 can be varied by turning the plug 84, and thus the exact left-to-right location of the extended position of the slave piston 62 can be precisely set as follows. The plug 84 is first tightened until the spring 11~ is compressed and the second portion 96 of the piston member 90 abuts the wall 78. The threaded adjustment member 110 is then tightened until the flange portion 112 just closes the switch, iOe., until the switch member 134 just contacts the second terminal 132. The plug 84 is then backed out so that the spring 114 is less co-mpressed, but so that the spring 114 is still compressed enough to keep the switch closed. Load is then applied to the polish rod 1, and the plug 84 is adjusted until the ~orce sf spring 114 is just high enough to retain the second portion 96 against the wall 78 at the minimum lvad and thereby cause the switch to be closed. Consequently, at this setting of the plug and the spring force the variations in the load will cause the switch to be repeatedly turned on and off.
Thus, the extended position of the slav~ piston 62 is set during this final adjustment of the plug 84.
The ability to thus adjust the extended position of th~
slave plston 62 allows a user to set up the indicating device such that the flange portion 112 of the threaded adjustment member 110 just closes the contact switch when the slave piston 62 i8 in the retracted positionO The indicating device can therefore be set up such that the ~ED indicator 138 lights just once during each cycle of a reciproca~ingly moving part such as a polish rod of a pump~ and the indicating device is therefore .
~` :
ll--able to prvduce an indication of the variation in the polish rod load. Adjustment of the point at which the contact switch is closed can also be accomp~ished by turning of the threaded adjustment washer 110 on the rod 92, which varies the distance between the piston member 90 and the flange portion 112.
The adjustment features of the present invention allow a single indicating device to be used with any of a wide range o~
wells, both deep and shallow, since the indicating device can be adjusted to indicate a wide variation of loads. The indicating device can also use the adjustment features to compensate for changes in elasticity of the spring 114, and small losses of fluid in the master and slave piston and cylinder arrangements.
Accordingly, the adjustment features allow the indicating device o~ the present invention to be used ~or long periods of time without repair or replacement.
The indication of load variation in a reciprocatingly moving part such as a polish rod of a pump, which is provided by the indicating device of the present invention, is a simple and reliable indication which can readily be monitored by an operator who may not have a high level of technological expertise. For example, when the indicating device of the present invention is being used with ~ pump which i~ experiencing a desired load variation, an operator will see a simple cyclical on/off pattern o~ flashing from the LED indicator of the indicating device. As long as the on/off pattern of flashing continue~, and continues at the same frequency, the operator is given a good indication that the load is varying as desired. If the on/off pattern stops, i.e., if thP indicator stays on or stays off, or if the frequency of flashing of the LED indicator changes, the operator knows that the pump has completely stopped operating, that the connection between the polish rod and the bridle has somehow failed, that a rod break has occurred and that the polish rod is no longer supporting a heavy weight, or that some other abnormal condition of the pump has occurred. With a little experience with the indicating device, an operator can quickly recognize the condition which a particular flashing pattern indicates. Thus, ' .
~~2-the indicating device of the present invention is extremely simple to monitor.
Additionally, since the indicating device is simple and rugged in construction, it is subject to only infrequent break downs, and, when it does ~reak down, it is relatively simple to repair, since it contains no complex electronics~
It is to be appreciated that the advantages of the present invention can be obtained through the use of any of a number of fluids in the master and slave pistons and cylinders. For example, hydraulic fluid, oil, air, or other fluids may be used.
Also, although the master and slave pistons and cylinders are shown in the drawings as being made of metalr they could also be advantageously made of any number of materials, such as plastic, ceramic, or combinations thereof. It is also to be understood that the indicating circuit arrangement may be mounted separately from th~ slave cylinder if desired, and that the slave piston and cylinder may be separate from the main piston and cylinder with, ~or example, a hose keeping the main and slave piston and cylinders in fluid communication.
Indicating circuit arrangements which are different from the one disclosed may be used, and advantages of the present invention obtained therefromO For example, a circuit which includes a transistor may be used in the present inventiQn, such that closing of the contact switch causes the transistor to cut the flow of curr0nt to the LED indicator, and therefore such that the LED indicator normally provides a lighted indication, and is not lit only when the contact switch is closed. Also, the contact switch of the present invention may be replaced with another switch such as a magnetic switch, and the LED indicator may be replaced with another indicator such as a buzzer, a bell, or a whistle, and advantages obtained therefrom. The indicating circuit could also be completely replaced by a mechanical noisemaker which is activated once during each cycle of the slave piston. Also, the indicating circuit could be modified to allow graphic recording of the load variation on the polish rod, or to cause ~hut down of the power supply to the pump whan the load variation becomes irregular.
.
.
, , : : ~.~ :; :
- ~
~ ~t ~
At least some of the advantages of ~he present invention are also achievable if the slav~ piston and cy]inder arrangement is arranged in fluid communication with the master piston and cylinder arrangement through a passageway through the master piston~ Additionally, the slave piston may be held fixed to the master piston and cylinder arrangement, and the slave cylinder may be arranged movably, and some advantages obtained therefrom.
The principles, a preferred embodiment and the mode of operation of the present invention have been described in the foregoing specifica~ion. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiment disclosed. The embodiment is therefore to be regarded as illustrative rather than restrictive. Variations and changes may be made by others without deparrting from the spirit of the present invention. Accordingly, it is expr ssly intended that all such variations and changes which fall within the spirit and scope of the present invention as defined in the claims be embraced thereby.
. : .
Claims (22)
1. An indicating device for indicating variations in a load on a reciprocably moving part, comprising:
reciprocating moving means for reciprocatingly moving in response to the variations in the load;
indicating means for providing an indication; and switch means for switching between an open state and a closed state, and for causing said indicating means to provide said indication when said switch means is in one of said open and closed states, said reciprocating moving means causing said switch means to switch to said one of said open and closed states once during each cycle of said reciprocating movement of said reciprocating moving means.
reciprocating moving means for reciprocatingly moving in response to the variations in the load;
indicating means for providing an indication; and switch means for switching between an open state and a closed state, and for causing said indicating means to provide said indication when said switch means is in one of said open and closed states, said reciprocating moving means causing said switch means to switch to said one of said open and closed states once during each cycle of said reciprocating movement of said reciprocating moving means.
2. An indicating device as claimed in claim 1, wherein said reciprocating moving means includes a master piston and cylinder enclosing a fluid therebetween, and a slave piston and cylinder also enclosing a fluid therebetween which is in fluid communication with said fluid enclosed by said master piston and cylinder, a portion of one of said slave piston and cylinder causing said switch means to switch to said one of said open and closed states once during each cycle of said reciprocating movement.
3. An indicating device as claimed in claim 2, wherein said master piston and cylinder are connectable to the part such that said master piston and cylinder move reciprocally with respect to each other to produce a cyclically varying pressure in said fluids enclosed by said master piston and cylinder and said slave piston and cylinder, said cyclically varying pressure causing said slave piston and cylinder to move reciprocally relative to each other such that said portion of said one of said slave piston and cylinder contacts and moves said switch means to said one of said open and closed states once during each cycle of said relative reciprocating movement of said slave piston and cylinder.
4. An indicating device as claimed in claim 2, wherein said slave piston is movable between a retracted position and a extended position, and is spring biased towards said retracted position.
5. An indicating device as claimed in claim 2, wherein said slave piston is movable between a retracted position and an extended position, and wherein said slave piston moves said switch means to said closed position when said slave piston is in said retracted position, to cause said indicating means to produce said indication of reciprocating movement.
6. An indicating device as claimed in claim 1, wherein said indicating means and said switch means are located in a circuit, said switch means causing current to flow through said circuit and activate said indicating means so that said indicating means produces said indication of reciprocating movement when said switch means is in said closed state.
7. An indicating device as claimed in claim 1, wherein said indicating means is an LED.
8. An indicating device as claimed in claim 2, wherein said portion is a flange portion on said slave piston, wherein said switch means includes a contact switch which includes a switch member which is spring biased towards an open position, and wherein said flange portion contacts said switch member and closes it against said spring bias once during each cycle of reciprocating movement of said slave piston.
9. An indicating device as claimed in claim 2, wherein said master piston and cylinder are both toroidally-shaped and are placed around the part.
10. An indicating device as claimed in claim 1, wherein said reciprocating moving means includes a toroidally-shaped piston and cylinder arrangement.
11. An indicating device as claimed in claim 1, further including adjustment means for adjusting said indicating device to allow said indicating device to provide indication over a wide range of loads.
12. An indicating device as claimed in claim 11, wherein said reciprocating moving means includes a slave piston and cylinder moving reciprocably with respect to each other, and said adjustment means includes a plug threaded into said slave cylinder and a spring extending between said plug and said slave piston, movement of said plug within said slave cylinder adjusting a stroke of said slave piston.
13. A polish rod load indicating device, comprising:
a master piston and cylinder enclosing a fluid therebetween, said master piston and cylinder being connectable to the polish rod such that one of said master piston and cylinder moves cyclically with respect to the other of said master piston and cylinder;
a slave piston and cylinder enclosing a fluid therebetween which is in communication with said fluid enclosed by said master piston and cylinder, said cyclical movement of said one of said master piston and cylinder producing a cyclically varying pressure in said fluids, said cyclically varying pressure causing one of said slave piston and cylinder to move cyclically relative to the other of said slave piston and cylinder;
an indicator; and a switch, said indicator producing a polish rod load indication signal in response to operation of said switch, said cyclically moving one of said slave piston and cylinder operating said switch to cause said indicator to produce said polish rod load indication signal once during each cycle of said cyclical movement of said cyclically moving one of said slave piston and cylinder.
a master piston and cylinder enclosing a fluid therebetween, said master piston and cylinder being connectable to the polish rod such that one of said master piston and cylinder moves cyclically with respect to the other of said master piston and cylinder;
a slave piston and cylinder enclosing a fluid therebetween which is in communication with said fluid enclosed by said master piston and cylinder, said cyclical movement of said one of said master piston and cylinder producing a cyclically varying pressure in said fluids, said cyclically varying pressure causing one of said slave piston and cylinder to move cyclically relative to the other of said slave piston and cylinder;
an indicator; and a switch, said indicator producing a polish rod load indication signal in response to operation of said switch, said cyclically moving one of said slave piston and cylinder operating said switch to cause said indicator to produce said polish rod load indication signal once during each cycle of said cyclical movement of said cyclically moving one of said slave piston and cylinder.
14. A polish rod load indicating device as claimed in claim 13, wherein said slave cylinder is held fixed to said other of said master piston and cylinder, and said slave piston is movable relative to said slave cylinder such that said slave piston is said cyclically movable one of said slave piston and cylinder.
15. A polish rod load indicating device as claimed in claim 14, wherein said slave piston is movable between a retracted position and a extended position, and is spring biased towards said retracted position.
16. A polish rod load indicating device as claimed in claim 14, wherein said slave piston is movable between a retracted position and an extended position, and wherein said slave piston abuts said switch and thereby closes it when said slave piston is in said retracted position, to cause said indicator to produce said polish rod load indication signal.
17. A polish rod load indicating device as claimed in claim 13, wherein said indicator and said switch are located in a circuit, closing of said switch causing current to flow through said circuit and activate said indicator to produce said polish rod load indication signal.
18. A polish rod load indicating device as claimed in claim 13, wherein said indicator is an LED.
19. A polish rod load indicating device as claimed in claim 13, further comprising:
a flange portion on said cyclically moving one of said slave piston and cylinder, wherein said switch is a contact switch which includes a switch member which is spring biased towards an open position, and wherein said flange portion contacts said switch member and closes it against said spring bias once during each cycle of said cyclical movement.
a flange portion on said cyclically moving one of said slave piston and cylinder, wherein said switch is a contact switch which includes a switch member which is spring biased towards an open position, and wherein said flange portion contacts said switch member and closes it against said spring bias once during each cycle of said cyclical movement.
20. A polish rod load indicating device as claimed in claim 13, wherein said master piston and cylinder are both toroidally-shaped and are placed around the polish rod.
21. A polish rod load indicating device as claimed in claim 13, further comprising:
a plug threaded into said slave cylinder; and a spring extending between said slave piston and said plug, movement of said plug within said slave cylinder adjusting a stroke of said slave piston.
a plug threaded into said slave cylinder; and a spring extending between said slave piston and said plug, movement of said plug within said slave cylinder adjusting a stroke of said slave piston.
22. A polish rod load indicating device for indicating variation in a polish rod load, comprising:
a toroidally-shaped master piston;
a toroidally-shaped master cylinder cooperating with said master piston to enclose a fluid, said master piston and cylinder being connected to the polish rod;
a slave piston and cylinder enclosing a fluid which is in fluid communication with said fluid enclosed by said master piston and cylinder, said slave piston including a flange portion and being movable between extended and retracted positions within said slave cylinder, said slave piston being spring biased towards said retracted position;
a switch, said switch being movable between an open position and a closed position and being spring biased towards said open position; and an indicator, said indicator producing an indication when current flows therethrough, wherein said master piston is cyclically moveable in response to cyclical movement of the polish rod to produce a cyclically varying pressure in said fluids, said cyclically varying pressure causing said slave piston to move cyclically between said extended and retracted positions such that said flange portion of said slave piston moves said switch to said closed position when said slave piston is in said retracted position, closing of said switch causing current to flow through said indicator so that said indicator provides said indication once during each cycle of said cyclical movement of said master piston to indicate variation in the polish rod load.
a toroidally-shaped master piston;
a toroidally-shaped master cylinder cooperating with said master piston to enclose a fluid, said master piston and cylinder being connected to the polish rod;
a slave piston and cylinder enclosing a fluid which is in fluid communication with said fluid enclosed by said master piston and cylinder, said slave piston including a flange portion and being movable between extended and retracted positions within said slave cylinder, said slave piston being spring biased towards said retracted position;
a switch, said switch being movable between an open position and a closed position and being spring biased towards said open position; and an indicator, said indicator producing an indication when current flows therethrough, wherein said master piston is cyclically moveable in response to cyclical movement of the polish rod to produce a cyclically varying pressure in said fluids, said cyclically varying pressure causing said slave piston to move cyclically between said extended and retracted positions such that said flange portion of said slave piston moves said switch to said closed position when said slave piston is in said retracted position, closing of said switch causing current to flow through said indicator so that said indicator provides said indication once during each cycle of said cyclical movement of said master piston to indicate variation in the polish rod load.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US61895490A | 1990-11-28 | 1990-11-28 | |
| US618,954 | 1990-11-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2054988A1 true CA2054988A1 (en) | 1992-05-29 |
Family
ID=24479826
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002054988A Abandoned CA2054988A1 (en) | 1990-11-28 | 1991-11-07 | Indicating device |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2054988A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014040264A1 (en) * | 2012-09-14 | 2014-03-20 | 中国石油天然气股份有限公司 | Method and system for measuring dynamic liquid level of oil well |
-
1991
- 1991-11-07 CA CA002054988A patent/CA2054988A1/en not_active Abandoned
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014040264A1 (en) * | 2012-09-14 | 2014-03-20 | 中国石油天然气股份有限公司 | Method and system for measuring dynamic liquid level of oil well |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued | ||
| FZDE | Discontinued |
Effective date: 19960507 |