CA1180916A - Position-sensing cylinder - Google Patents
Position-sensing cylinderInfo
- Publication number
- CA1180916A CA1180916A CA000408261A CA408261A CA1180916A CA 1180916 A CA1180916 A CA 1180916A CA 000408261 A CA000408261 A CA 000408261A CA 408261 A CA408261 A CA 408261A CA 1180916 A CA1180916 A CA 1180916A
- Authority
- CA
- Canada
- Prior art keywords
- support
- potentiometer
- wiper
- bore
- housing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
- F15B15/20—Other details, e.g. assembly with regulating devices
- F15B15/28—Means for indicating the position, e.g. end of stroke
- F15B15/2815—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT
- F15B15/2853—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT using potentiometers
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Actuator (AREA)
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
- Vehicle Body Suspensions (AREA)
- Looms (AREA)
- Characterised By The Charging Evacuation (AREA)
- Devices For Conveying Motion By Means Of Endless Flexible Members (AREA)
- Reciprocating Pumps (AREA)
- Fluid-Pressure Circuits (AREA)
- Valve Device For Special Equipments (AREA)
- Forklifts And Lifting Vehicles (AREA)
- Body Structure For Vehicles (AREA)
Abstract
POSITION-SENSING CYLINDER
Abstract of the Disclosure A position-sensing cylinder includes a hollow housing within which reciprocates a piston fixed to a hollow rod. A
hollow fitting is threadably attached to one end of the housing. A hollow metallic insert is press fitted into the hollow fitting. An elongated potentiometer support is received by and welded to the insert and is reciprocally received by the hollow rod. The support includes curved edges which slidably engage the wiper wall of the hollow rod and includes a planar support surface upon which are mounted resistive and conductive potentiometer strips. A hollow wiper carrier is mounted for movement with the piston and rod so that support reciprocates within the carrier and so that conductive wipers are maintained in contact with the potentiometer strips. The wiper carrier cooperates with the rod and the support to substantially prevent fluid flow in the vicinity of the wipers.
Abstract of the Disclosure A position-sensing cylinder includes a hollow housing within which reciprocates a piston fixed to a hollow rod. A
hollow fitting is threadably attached to one end of the housing. A hollow metallic insert is press fitted into the hollow fitting. An elongated potentiometer support is received by and welded to the insert and is reciprocally received by the hollow rod. The support includes curved edges which slidably engage the wiper wall of the hollow rod and includes a planar support surface upon which are mounted resistive and conductive potentiometer strips. A hollow wiper carrier is mounted for movement with the piston and rod so that support reciprocates within the carrier and so that conductive wipers are maintained in contact with the potentiometer strips. The wiper carrier cooperates with the rod and the support to substantially prevent fluid flow in the vicinity of the wipers.
Description
POSITION-SENSING CYLINDER
Background of the Invention This invention relates to a hydraulic cylinder with a poten-tiometric position-sensing transducer.
In hydraulic controls technology, it is often desirable to obtain feedback signals representing the operating position of a hydraulic cylinder. U. S. Patent No. 3,726,191 discloses one solution to this problem. The '191 cylinder has a resistance and conductor ele~ent support reciprocally received in a piston rod bore. A conductive wiper assembly is carried for movement with the piston and rod. However, the transducer construction of the '191 patent requires a relatively large transducer cross section which displaces a large volume of hydraulic fluid as the cylinder rod moves with respect to the transducer assembly. The bore required in the cylinder rod to accommodate such a transducer of large cross section and to provide an e,cape path for displaced hydraulic fluid is so large as to prevent its use in many hydrau-lic cylinders where compact size is required. Furthermore, the wiper contacts of the '191 patent are suspended in the fluid escape path, allowing flow forces to vibrate or bend the contact leaf, resulting in operating noise and loss of signal, respec-tively. Finally, the element support is supported only at one end by a plastic sealing element which is subject to mechanical stress and failures.
Summary of the Invention An advantage of the present invention is that it provides a position-sensing cylinder with good immunity to electrical noise caused by hydraulic flow-induced vibxation.
Another advantage of the present invention is that it pro-vides a position-sensing cylinder with a potentiometer element support with good rigidity and low cross-sectional area.
Another advantage of the present invention is that it pro-vides a potentiometer support element which is mechanically supported along the length of its engagement with the cylinder rod bore.
A further advantage of the present invention is that it provides a position-sensing cylinder with an improved fluid pressure seal which is spaced apart from the potentiometer support - and thus, not subject to mechanical stress caused by the support -- 40 of the potentiometer support.
These and other advantages are achieved by the present invention which provides a position-sensincJ c~linder with a T-shaped potentiometer support with one end welded or fixed to a hollow metallic terrninal which is press fitted into a fitting which is threadably attached to one end of the cylinder housing.
A ceramic plug seals the interior of the terminal, but pro~ides no support for and is separate from the support. Further support for the potentiometer support is provided by the sliding engage-ment between it and the wall of the rod bore within which the potentiometer support reciprocates. A wiper carrier cooperates with the bore wall and the potentiometer support to prevent fluid flow in the ~icinity of the flexible wiper contacts.
Brief Description of the Drawings FigO 1 is a cross-sectional view of the hydraulic cylinder for the present invention.
Fig. 2 is a partial sectional view of a portion of appli-cant's invention.
Fig. 3 is a view taken in the direction of arrows 3-3 of Fig. 2.
Fig. 4 is a view taken in the direction of arrows 4-4 of Fig. 2.
Fig. 5 is a top view of the terminal piece and the transducer support of the invention.
Figs. 6a through 6d are unscaled sectional views taken in the direction of arrows A-A, B-B, C-C and D-D, respectively, of Fig. 5.
Fig. 7 is an end view of the wiper carrier of the invention.
Detailed Description A fluid actuator or hydraulic cylinder 10 includes a housing 12 having a hollow cylindrical barrel portion 14 within which reciprocates a piston 16 connected to a rod 18. A rod-receiving cap 20 is threadably connected to an end of the housing 12. A
blind stepped bore 22 extends into the piston 16 and the rod 18.
As best seen in Fig. 2, the bore 22 has a large diameter portion 24 with a snap ring groove 26 therein and an annular ridge 28 at one end, a smaller diameter portion 30 and an annular shoulder 32 extending therebetween.
The housing 12 includes a threaded axial bore 34 for thread-ably receiving a steel outer transducer fitting 36. Fitting 36 includes a raised annular flange 38 for butting against a corres-~llB~
1 ponding houslng shoulder 40. An O-ring 42 maintains a fluid~
tight seal be-tween the fitting 36 and the housing 12. Fitting 36 also includes a stepped axial bore 44 extending therethrough.
A steel terminal piece 46 is press fitted into the fitting bore 44. Terminal 46 includes an annular groove 48 which receives a back-up ring 50 and an O-ring 52 for maintaining a fluid seal between the fitting 36 and the terminal 46. A portion of ceramic material 54 is formed in the hollow interior of the terminal 46 to form a hermakic seal -therein. The terminal 46 is formed as a separate piece from the ~itting 36 so that when the ceramic material 54 is heated within the terminal 46, the fitting 36 is not degraded by the high temperatures to which it would otherwise be e~posed if the fitting 36 and the terminal 46 were a single piece.
A steel support element 60 extends into the bore 22 from an end 62 received by and welded to the terminal 46. Thus, the end 62 of the support 60 is rigidly supported with respect to the housing 12 by metallic pieces 36 and 46, whereas other position-sensing cylinders, such as described in U. S. Patent No. 3,726,191, have supported the transducer support element by press fitting the support into a plastic insulating sleeve, which is, in turn,received by a metallic threaded fitting. In this arrangement, the transducer support is less rigidly supported at its supported end and the plastic insulating material is subject to stress failures, such as cracking, which then degrades its sealing properties. Furthermore, in the instant invention, the ceramic seal 54 is subject to very little mechanical stress caused by suppoxting the support 60. Instead, the ceramic seal 54 need only withstand the hydraulic pressures for which it is designed to withstand, with the result that the instant invention has increased integrity with respect to fluid pressure sealing.
The support 60 has a substantially T-shaped cross-sec~ion (as best seen in Figs. 3 and 4) formed by a cross piece 64 away from which perpendicularly extends a stiEfening ridge 66. The side of cross piece 64, which is opposite the ridge 66, forms a - planar support surface 68~ A circular edged notch 70 is formed in the end 62 of support 60, as best seen in ~igs. 2 and 4.
The cross piece 64 and the ridge 66 divide the bore 22 into three fluid chambers 65, 67 and 69, of which chambers 65 and 67 are visible in Fig. 2. As best seen in Figs. 2 a~ld 3, the curved 1 outer peripheral surfaces 59, 61 and 63 of the support 60 slidably engage the wall of the bore 22. This engagement adds rigidity to the support 60 and helps to prevent deformation of the support 60 and reduces vibration to which the support 60 would be subjec~ if S it were cantilevered or supported merely at one end.
As best seen ln Figs. 5 and 6a-d, a resistance or potenti-ometer assembly 72 is placed on the planar support surface 68 of the cross piece 64. The assembly includes an electrically insu]-ating base 74 fixed to the support surface 68 and which may be formed of material such as "Kapton", a trademark material avail-able from DuPont~
The assembly 72 also includes a conductive plas-tic potenti-ometer element 76, of which the largest or elongated central portion thereof is laid directly upon the insulating base 74.
The ends 78 and 80 of the potentiometer element are overlaid onto portions of copper or metallic electrical conductive ground and power strips 82 and 84, respectively. The potentiometer element 76 terminates at edges 79 and 81, respectively. Conductive ground strip 82 terminates at edge 83, under the end 78 of the potentiometer element 76, as shown in dashed line in Fig. 5. A
conductor 86 is soldered to the other end of ground strip 82.
Conductive power strip 84 terminates at an edge 85 under end 80 of the potentiometer element 76, as also shown in dashed line in Fig. 5. The overlaps between the conductive strips 82/ 84 and the potentiometer element ends 78, 80 need only be sufficient to provide good electrical continuity therebetween. The other end of power strip 84 is joined via a solder joint to a conductor 88.
A metallic or electrical conductive commutator strip 90 is also positioned on the insulating base 74. Commutator strip 90 extends from an edge indicated by reference numeral 92 to an end 94 to which is soldered to a conductor 96. An overlay strip 98 of conductive plastic material is positioned on top of the commutator strip 90 and extends from edge 99 to an edge also indica~ed by reference numeral 92. The major portion of the power strip 84 is separated -from the commutator strip 90 by the middle or potenti-ometer strip 76 to reduce the possibility of metallic particles forming undesirable short circuit connections between the power strip 84 and the commutator strip 90. Also note that the trans-ducer element 72 is not received in a recess or channel in the support 60, but rather is positioned on top of the planar support surface 68. The absence of a recess or channel reduces the likelihood of metallic particles forming undesirable short circuit connections between the support 60 and the outer edges of the power strip 84 and the commutator strip 90. For clarity, the thicknesses of the various strips in Figs. 6a-d are exaggerated.
The conductors 86, 88 and 96 extend from their solder joints, through the notch 70, the terminal member 46 and the ceramic seal 54 to respective connector terminals 100, 102 and 104, two of which are visible in Fig. 2. A conventional ~emale plug-t~pe connector may be coupled to the connector terminals 100, 102 and 104 so that electrical signals may be extracted therefrom.
A wiper carrier 110 is received by bore portion 24 of the bore 22, as best seen in Fig. 2. The wiper carrier 110 has a generally cy]indrical body 112 of an insulating material such as glass-reinforced nylon with an annular rabbet 114 in one end thereof. The rabbet 114 registers with the ridge 28 only when the carrier 110 is properly mounted in the bore portion 24, otherwise, the annular ridge 28 will prevent the carrier 110 from being inserted far enough into bore portion 24 to allow insertion of snap ring 126 into snap ring groove 26. A wiper support flange 116 extends inwardly from a portion of the body 112. A
two-pronged conductive wiper 118 is embedded in and supported by the flange 116 so that prongs 120 and 122 resiliently and slid-ably engage the surfaces of plastic conductive strip 98 above commutator strip 90 and the potentiometer element portion 76, respectively. The wiper 118 is exposed to the fluid in chamber65. As best seen in Fig. 7, the prongs 120 and 122 have multiple fingers. A rectangular recess 124 is formed in the inner surface 125 of the carrier flange 116 so that the inner surface 125 closely registers with the surface 68 of the support element 60 and with the transducer element 72. The carrier 110 is coupled for movement with the rod 18 and piston 16 between snap ring 126 and a resilient wave washer 128.
When the piston 16 and rod 18 move back and forth with respect to the housing 12 and the support 60, fluid flows into and out of chamber 65, around the end 129 of the support 60 and via chambers 67 and 69. However, the close sliding fit between the inner surface 1~5 and surface 68 and element 72 substantially prevents fluid flow into or out of chamber 65 via the wiper c~rrier 110, thus reducing flow-induced turbulence in the vicinit~
. .
of the wiper 118. Thls reduced turbulence prevents turbulence~
induced vibrat.ions in the wiper 118 which could otherwise intro duce noise into the signals picked up by the wiper 118.
Mode of Operation In operation, a voltage potential is applied across terminals 102 and 100 to apply a corresponding voltage potential across the resistance element 760 As the piston 16 and rod 18 move back and forth within the housing 12, the wiper 118 moves with the piston 16 and rod 18 and with respect to the support 60 and the trans-ducer element 72. Thus, the voltage or potential to which the wiper 118 is subjected varies from ground potential to approxi-mately the voltage at the power strip 84, depending upon the longitudinal position of the wiper 118 relative to the resistance element 76. The voltage on wiper 118 is communicated to the exterior of the cylinder housing 12 via con~utator strips 98 and 90, conductor 96 and connector terminal 104, from where it can be monitored to indicate the position of the cylinder 10.
Background of the Invention This invention relates to a hydraulic cylinder with a poten-tiometric position-sensing transducer.
In hydraulic controls technology, it is often desirable to obtain feedback signals representing the operating position of a hydraulic cylinder. U. S. Patent No. 3,726,191 discloses one solution to this problem. The '191 cylinder has a resistance and conductor ele~ent support reciprocally received in a piston rod bore. A conductive wiper assembly is carried for movement with the piston and rod. However, the transducer construction of the '191 patent requires a relatively large transducer cross section which displaces a large volume of hydraulic fluid as the cylinder rod moves with respect to the transducer assembly. The bore required in the cylinder rod to accommodate such a transducer of large cross section and to provide an e,cape path for displaced hydraulic fluid is so large as to prevent its use in many hydrau-lic cylinders where compact size is required. Furthermore, the wiper contacts of the '191 patent are suspended in the fluid escape path, allowing flow forces to vibrate or bend the contact leaf, resulting in operating noise and loss of signal, respec-tively. Finally, the element support is supported only at one end by a plastic sealing element which is subject to mechanical stress and failures.
Summary of the Invention An advantage of the present invention is that it provides a position-sensing cylinder with good immunity to electrical noise caused by hydraulic flow-induced vibxation.
Another advantage of the present invention is that it pro-vides a position-sensing cylinder with a potentiometer element support with good rigidity and low cross-sectional area.
Another advantage of the present invention is that it pro-vides a potentiometer support element which is mechanically supported along the length of its engagement with the cylinder rod bore.
A further advantage of the present invention is that it provides a position-sensing cylinder with an improved fluid pressure seal which is spaced apart from the potentiometer support - and thus, not subject to mechanical stress caused by the support -- 40 of the potentiometer support.
These and other advantages are achieved by the present invention which provides a position-sensincJ c~linder with a T-shaped potentiometer support with one end welded or fixed to a hollow metallic terrninal which is press fitted into a fitting which is threadably attached to one end of the cylinder housing.
A ceramic plug seals the interior of the terminal, but pro~ides no support for and is separate from the support. Further support for the potentiometer support is provided by the sliding engage-ment between it and the wall of the rod bore within which the potentiometer support reciprocates. A wiper carrier cooperates with the bore wall and the potentiometer support to prevent fluid flow in the ~icinity of the flexible wiper contacts.
Brief Description of the Drawings FigO 1 is a cross-sectional view of the hydraulic cylinder for the present invention.
Fig. 2 is a partial sectional view of a portion of appli-cant's invention.
Fig. 3 is a view taken in the direction of arrows 3-3 of Fig. 2.
Fig. 4 is a view taken in the direction of arrows 4-4 of Fig. 2.
Fig. 5 is a top view of the terminal piece and the transducer support of the invention.
Figs. 6a through 6d are unscaled sectional views taken in the direction of arrows A-A, B-B, C-C and D-D, respectively, of Fig. 5.
Fig. 7 is an end view of the wiper carrier of the invention.
Detailed Description A fluid actuator or hydraulic cylinder 10 includes a housing 12 having a hollow cylindrical barrel portion 14 within which reciprocates a piston 16 connected to a rod 18. A rod-receiving cap 20 is threadably connected to an end of the housing 12. A
blind stepped bore 22 extends into the piston 16 and the rod 18.
As best seen in Fig. 2, the bore 22 has a large diameter portion 24 with a snap ring groove 26 therein and an annular ridge 28 at one end, a smaller diameter portion 30 and an annular shoulder 32 extending therebetween.
The housing 12 includes a threaded axial bore 34 for thread-ably receiving a steel outer transducer fitting 36. Fitting 36 includes a raised annular flange 38 for butting against a corres-~llB~
1 ponding houslng shoulder 40. An O-ring 42 maintains a fluid~
tight seal be-tween the fitting 36 and the housing 12. Fitting 36 also includes a stepped axial bore 44 extending therethrough.
A steel terminal piece 46 is press fitted into the fitting bore 44. Terminal 46 includes an annular groove 48 which receives a back-up ring 50 and an O-ring 52 for maintaining a fluid seal between the fitting 36 and the terminal 46. A portion of ceramic material 54 is formed in the hollow interior of the terminal 46 to form a hermakic seal -therein. The terminal 46 is formed as a separate piece from the ~itting 36 so that when the ceramic material 54 is heated within the terminal 46, the fitting 36 is not degraded by the high temperatures to which it would otherwise be e~posed if the fitting 36 and the terminal 46 were a single piece.
A steel support element 60 extends into the bore 22 from an end 62 received by and welded to the terminal 46. Thus, the end 62 of the support 60 is rigidly supported with respect to the housing 12 by metallic pieces 36 and 46, whereas other position-sensing cylinders, such as described in U. S. Patent No. 3,726,191, have supported the transducer support element by press fitting the support into a plastic insulating sleeve, which is, in turn,received by a metallic threaded fitting. In this arrangement, the transducer support is less rigidly supported at its supported end and the plastic insulating material is subject to stress failures, such as cracking, which then degrades its sealing properties. Furthermore, in the instant invention, the ceramic seal 54 is subject to very little mechanical stress caused by suppoxting the support 60. Instead, the ceramic seal 54 need only withstand the hydraulic pressures for which it is designed to withstand, with the result that the instant invention has increased integrity with respect to fluid pressure sealing.
The support 60 has a substantially T-shaped cross-sec~ion (as best seen in Figs. 3 and 4) formed by a cross piece 64 away from which perpendicularly extends a stiEfening ridge 66. The side of cross piece 64, which is opposite the ridge 66, forms a - planar support surface 68~ A circular edged notch 70 is formed in the end 62 of support 60, as best seen in ~igs. 2 and 4.
The cross piece 64 and the ridge 66 divide the bore 22 into three fluid chambers 65, 67 and 69, of which chambers 65 and 67 are visible in Fig. 2. As best seen in Figs. 2 a~ld 3, the curved 1 outer peripheral surfaces 59, 61 and 63 of the support 60 slidably engage the wall of the bore 22. This engagement adds rigidity to the support 60 and helps to prevent deformation of the support 60 and reduces vibration to which the support 60 would be subjec~ if S it were cantilevered or supported merely at one end.
As best seen ln Figs. 5 and 6a-d, a resistance or potenti-ometer assembly 72 is placed on the planar support surface 68 of the cross piece 64. The assembly includes an electrically insu]-ating base 74 fixed to the support surface 68 and which may be formed of material such as "Kapton", a trademark material avail-able from DuPont~
The assembly 72 also includes a conductive plas-tic potenti-ometer element 76, of which the largest or elongated central portion thereof is laid directly upon the insulating base 74.
The ends 78 and 80 of the potentiometer element are overlaid onto portions of copper or metallic electrical conductive ground and power strips 82 and 84, respectively. The potentiometer element 76 terminates at edges 79 and 81, respectively. Conductive ground strip 82 terminates at edge 83, under the end 78 of the potentiometer element 76, as shown in dashed line in Fig. 5. A
conductor 86 is soldered to the other end of ground strip 82.
Conductive power strip 84 terminates at an edge 85 under end 80 of the potentiometer element 76, as also shown in dashed line in Fig. 5. The overlaps between the conductive strips 82/ 84 and the potentiometer element ends 78, 80 need only be sufficient to provide good electrical continuity therebetween. The other end of power strip 84 is joined via a solder joint to a conductor 88.
A metallic or electrical conductive commutator strip 90 is also positioned on the insulating base 74. Commutator strip 90 extends from an edge indicated by reference numeral 92 to an end 94 to which is soldered to a conductor 96. An overlay strip 98 of conductive plastic material is positioned on top of the commutator strip 90 and extends from edge 99 to an edge also indica~ed by reference numeral 92. The major portion of the power strip 84 is separated -from the commutator strip 90 by the middle or potenti-ometer strip 76 to reduce the possibility of metallic particles forming undesirable short circuit connections between the power strip 84 and the commutator strip 90. Also note that the trans-ducer element 72 is not received in a recess or channel in the support 60, but rather is positioned on top of the planar support surface 68. The absence of a recess or channel reduces the likelihood of metallic particles forming undesirable short circuit connections between the support 60 and the outer edges of the power strip 84 and the commutator strip 90. For clarity, the thicknesses of the various strips in Figs. 6a-d are exaggerated.
The conductors 86, 88 and 96 extend from their solder joints, through the notch 70, the terminal member 46 and the ceramic seal 54 to respective connector terminals 100, 102 and 104, two of which are visible in Fig. 2. A conventional ~emale plug-t~pe connector may be coupled to the connector terminals 100, 102 and 104 so that electrical signals may be extracted therefrom.
A wiper carrier 110 is received by bore portion 24 of the bore 22, as best seen in Fig. 2. The wiper carrier 110 has a generally cy]indrical body 112 of an insulating material such as glass-reinforced nylon with an annular rabbet 114 in one end thereof. The rabbet 114 registers with the ridge 28 only when the carrier 110 is properly mounted in the bore portion 24, otherwise, the annular ridge 28 will prevent the carrier 110 from being inserted far enough into bore portion 24 to allow insertion of snap ring 126 into snap ring groove 26. A wiper support flange 116 extends inwardly from a portion of the body 112. A
two-pronged conductive wiper 118 is embedded in and supported by the flange 116 so that prongs 120 and 122 resiliently and slid-ably engage the surfaces of plastic conductive strip 98 above commutator strip 90 and the potentiometer element portion 76, respectively. The wiper 118 is exposed to the fluid in chamber65. As best seen in Fig. 7, the prongs 120 and 122 have multiple fingers. A rectangular recess 124 is formed in the inner surface 125 of the carrier flange 116 so that the inner surface 125 closely registers with the surface 68 of the support element 60 and with the transducer element 72. The carrier 110 is coupled for movement with the rod 18 and piston 16 between snap ring 126 and a resilient wave washer 128.
When the piston 16 and rod 18 move back and forth with respect to the housing 12 and the support 60, fluid flows into and out of chamber 65, around the end 129 of the support 60 and via chambers 67 and 69. However, the close sliding fit between the inner surface 1~5 and surface 68 and element 72 substantially prevents fluid flow into or out of chamber 65 via the wiper c~rrier 110, thus reducing flow-induced turbulence in the vicinit~
. .
of the wiper 118. Thls reduced turbulence prevents turbulence~
induced vibrat.ions in the wiper 118 which could otherwise intro duce noise into the signals picked up by the wiper 118.
Mode of Operation In operation, a voltage potential is applied across terminals 102 and 100 to apply a corresponding voltage potential across the resistance element 760 As the piston 16 and rod 18 move back and forth within the housing 12, the wiper 118 moves with the piston 16 and rod 18 and with respect to the support 60 and the trans-ducer element 72. Thus, the voltage or potential to which the wiper 118 is subjected varies from ground potential to approxi-mately the voltage at the power strip 84, depending upon the longitudinal position of the wiper 118 relative to the resistance element 76. The voltage on wiper 118 is communicated to the exterior of the cylinder housing 12 via con~utator strips 98 and 90, conductor 96 and connector terminal 104, from where it can be monitored to indicate the position of the cylinder 10.
Claims (13)
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A position-sensing hydraulic cylinder comprising:
a hollow cylindrical housing;
a piston and rod assembly reciprocal in the housing;
a walled bore extending longitudinally into the piston and rod assembly;
a support fixed with respect to the housing and received by the bore, the wall of the bore slidably engaging the support to maintain alignment of the support within the bore;
a potentiometer assembly including an elongated potentiometer element carried on a surface of the support and wiper means slidably and resiliently engaging the potentiometer element for maintaining electrical continuity therewith; and a wiper carrier fixed for movement with the piston and rod assembly for moving the wiper means relative to the potentiometer element, the potentiometer assembly generating signals represent-ing relative positions of the wiper means and the potentiometer element.
a hollow cylindrical housing;
a piston and rod assembly reciprocal in the housing;
a walled bore extending longitudinally into the piston and rod assembly;
a support fixed with respect to the housing and received by the bore, the wall of the bore slidably engaging the support to maintain alignment of the support within the bore;
a potentiometer assembly including an elongated potentiometer element carried on a surface of the support and wiper means slidably and resiliently engaging the potentiometer element for maintaining electrical continuity therewith; and a wiper carrier fixed for movement with the piston and rod assembly for moving the wiper means relative to the potentiometer element, the potentiometer assembly generating signals represent-ing relative positions of the wiper means and the potentiometer element.
2. The invention of claim 1, wherein the support comprises:
a cross piece having one side defining the planar support surface; and a stiffening ridge fixed to the cross piece and extending perpendicularly away therefrom, the cross piece and ridge together forming the support with a generally T-shaped cross sectional shape, the cross piece and stiffening ridge having curved per-ipheral edges slidably engaging the wall of the rod bore.
a cross piece having one side defining the planar support surface; and a stiffening ridge fixed to the cross piece and extending perpendicularly away therefrom, the cross piece and ridge together forming the support with a generally T-shaped cross sectional shape, the cross piece and stiffening ridge having curved per-ipheral edges slidably engaging the wall of the rod bore.
3. The invention of claim 1, further comprising:
a hollow fitting sealingly and removably attachable to an end of the housing;
a hollow sleeve sealingly coupled to and received by the hollow fitting and including means for rigidly supporting an end of the support; and a sealing plug formed within the hollow sleeve and spaced apart from the support for preventing fluid flow through the sleeve.
a hollow fitting sealingly and removably attachable to an end of the housing;
a hollow sleeve sealingly coupled to and received by the hollow fitting and including means for rigidly supporting an end of the support; and a sealing plug formed within the hollow sleeve and spaced apart from the support for preventing fluid flow through the sleeve.
4. The invention of claim 3, further comprising:
conductor means sealingly embedded in and extending through the sealing plug for communicating to the exterior of the cylinder the signals generated by the potentiometer assembly.
conductor means sealingly embedded in and extending through the sealing plug for communicating to the exterior of the cylinder the signals generated by the potentiometer assembly.
5. A position-sensing hydraulic cylinder comprising:
a hollow cylindrical housing;
a piston and rod assembly reciprocal in the housing;
a walled bore extending longitudinally into the piston and rod assembly;
a support fixed with respect to the housing and reciprocally received by the bore, the support including a planar support surface on one side thereof;
a potentiometer assembly including a potentiometer element disposed on the planar support surface, and an electrically conductive wiper means slidably and resiliently engaging the potentiometer element for maintaining electrical continuity therewith; and a wiper carrier coupled for movement with the piston and rod assembly for moving the wiper means relative to the potentiometer assembly, the wiper carrier having means cooperating with the support and the wall of the rod bore for substantially preventing fluid flow in the vicinity of the wiper means, the potentiometer assembly generating signals representing relative positions of the wiper means and the potentiometer element.
a hollow cylindrical housing;
a piston and rod assembly reciprocal in the housing;
a walled bore extending longitudinally into the piston and rod assembly;
a support fixed with respect to the housing and reciprocally received by the bore, the support including a planar support surface on one side thereof;
a potentiometer assembly including a potentiometer element disposed on the planar support surface, and an electrically conductive wiper means slidably and resiliently engaging the potentiometer element for maintaining electrical continuity therewith; and a wiper carrier coupled for movement with the piston and rod assembly for moving the wiper means relative to the potentiometer assembly, the wiper carrier having means cooperating with the support and the wall of the rod bore for substantially preventing fluid flow in the vicinity of the wiper means, the potentiometer assembly generating signals representing relative positions of the wiper means and the potentiometer element.
6. The invention of claim 5, wherein the support comprises:
a cross piece having one side defining the planar support surface; and a stiffening ridge fixed to the cross piece and extending perpendicularly away therefrom, the cross piece and ridge together forming the support with a generally T-shaped cross sectional shape.
a cross piece having one side defining the planar support surface; and a stiffening ridge fixed to the cross piece and extending perpendicularly away therefrom, the cross piece and ridge together forming the support with a generally T-shaped cross sectional shape.
7. The invention of claim 6, wherein:
the cross piece and ridge divide the rod bore into first, second and third chambers, the cross piece separating the first chamber from the second and third chambers, the ridge separating the second and third chambers from each other, the second and third chambers being open at both ends thereof to permit fluid flow therethrough upon relative movement between the piston and the housing, the wiper means being exposed to fluid in the first chamber, and the wiper carrier cooperating with the wall of the bore and with the cross piece to close one end of the first chamber thereby substantially preventing fluid flow in the vic-inity of the wiper means.
the cross piece and ridge divide the rod bore into first, second and third chambers, the cross piece separating the first chamber from the second and third chambers, the ridge separating the second and third chambers from each other, the second and third chambers being open at both ends thereof to permit fluid flow therethrough upon relative movement between the piston and the housing, the wiper means being exposed to fluid in the first chamber, and the wiper carrier cooperating with the wall of the bore and with the cross piece to close one end of the first chamber thereby substantially preventing fluid flow in the vic-inity of the wiper means.
8. The invention of claim 6, wherein:
the cross piece and ridge have curved outer peripheral surfaces slidably engaging the wall of the rod bore, engagement between the rod bore wall and the peripheral support surfaces resisting deformation of the support.
the cross piece and ridge have curved outer peripheral surfaces slidably engaging the wall of the rod bore, engagement between the rod bore wall and the peripheral support surfaces resisting deformation of the support.
9. The invention of claim 5, wherein:
the wiper carrier comprises a cylindrical body having a rabbet in one end of the outer peripheral surface thereof; and the rod bore being a stepped bore with large and small diameter portions interconnected by an annular shoulder, the large diameter portion receiving the wiper carrier and having a raised annular ridge at one end thereof for registering with the rabbet in the wiper carrier, the annular shoulder providing an abutment for limiting relative movement between the wiper carrier and the rod.
the wiper carrier comprises a cylindrical body having a rabbet in one end of the outer peripheral surface thereof; and the rod bore being a stepped bore with large and small diameter portions interconnected by an annular shoulder, the large diameter portion receiving the wiper carrier and having a raised annular ridge at one end thereof for registering with the rabbet in the wiper carrier, the annular shoulder providing an abutment for limiting relative movement between the wiper carrier and the rod.
10. The invention of claim 5, further comprising:
a hollow fitting sealingly and removably attached to an end of the housing;
a hollow sleeve sealingly coupled to and received by the hollow fitting and including means rigidly supporting an end of the support; and a sealing plug formed within the hollow sleeve and spaced apart from the support for preventing fluid communication there-through.
a hollow fitting sealingly and removably attached to an end of the housing;
a hollow sleeve sealingly coupled to and received by the hollow fitting and including means rigidly supporting an end of the support; and a sealing plug formed within the hollow sleeve and spaced apart from the support for preventing fluid communication there-through.
11. A position-sensing hydraulic cylinder comprising:
a hollow cylindrical housing;
a piston and rod assembly reciprocal in the housing;
a walled bore extending longitudinally into the piston and rod assembly;
a support rigidly fixed with respect to the housing and reciprocally received by the bore, the support including a cross piece having one side defining a planar support surface and a stiffening ridge extending perpendicularly away from another side of the cross piece, the support having a generally T-shaped cross section;
a potentiometer assembly having a potentiometer element disposed on the planar support surface, and wiper means slidably and resiliently engaging the potentiometer element for maintaining electrical continuity therewith; and a wiper carrier fixed for movement with the piston and rod assembly for carrying the wiper means, the wiper carrier including means cooperating with the support for substantially preventing fluid flow in the vicinity of the wiper means.
a hollow cylindrical housing;
a piston and rod assembly reciprocal in the housing;
a walled bore extending longitudinally into the piston and rod assembly;
a support rigidly fixed with respect to the housing and reciprocally received by the bore, the support including a cross piece having one side defining a planar support surface and a stiffening ridge extending perpendicularly away from another side of the cross piece, the support having a generally T-shaped cross section;
a potentiometer assembly having a potentiometer element disposed on the planar support surface, and wiper means slidably and resiliently engaging the potentiometer element for maintaining electrical continuity therewith; and a wiper carrier fixed for movement with the piston and rod assembly for carrying the wiper means, the wiper carrier including means cooperating with the support for substantially preventing fluid flow in the vicinity of the wiper means.
12. A position-sensing cylinder comprising:
a hollow cylindrical housing;
a piston and rod assembly reciprocal in the housing;
a walled bore extending longitudinally into the piston and rod assembly;
a hollow fitting sealingly and removably attachable to an end of the housing;
a support reciprocally and slidably received by the bore;
a hollow sleeve sealingly coupled to and received by the hollow fitting and including means for rigidly supporting an end of the support;
a sealing plug formed within the sleeve at a position spaced apart from the support for preventing fluid communication through the hollow sleeve;
a potentiometer assembly including a potentiometer element disposed on a surface of the support and electrically conductive wiper means slidably and resiliently engaging the potentiometer element and for maintaining electrical continuity therewith; and a wiper carrier fixed for movement with the piston and rod assembly for moving the wiper means relative to the potentiometer element, the potentiometer assembly generating signals represent-ing relative positions of the wiper means and the potentiometer element.
a hollow cylindrical housing;
a piston and rod assembly reciprocal in the housing;
a walled bore extending longitudinally into the piston and rod assembly;
a hollow fitting sealingly and removably attachable to an end of the housing;
a support reciprocally and slidably received by the bore;
a hollow sleeve sealingly coupled to and received by the hollow fitting and including means for rigidly supporting an end of the support;
a sealing plug formed within the sleeve at a position spaced apart from the support for preventing fluid communication through the hollow sleeve;
a potentiometer assembly including a potentiometer element disposed on a surface of the support and electrically conductive wiper means slidably and resiliently engaging the potentiometer element and for maintaining electrical continuity therewith; and a wiper carrier fixed for movement with the piston and rod assembly for moving the wiper means relative to the potentiometer element, the potentiometer assembly generating signals represent-ing relative positions of the wiper means and the potentiometer element.
13. A position-sensing hydraulic cylinder comprising:
a hollow cylindrical housing;
a piston and rod assembly reciprocal in the housing;
a walled bore extending longitudinally into the piston and rod assembly;
a support fixed with respect to the housing and received by the bore;
a hollow sleeve mounted in the housing and having means for rigidly supporting an end of the support;
a sealing plug formed within the sleeve at a position spaced apart from the support for preventing fluid communication through the sleeve;
a potentiometer assembly including an elongated potentiometer element carried on a surface of the support and wiper means slidably and resiliently engaging the potentiometer element for maintaining electrical continuity therewith; and a wiper carrier fixed for movement with the piston and rod assembly for moving the wiper means relative to the potentiometer element, the potentiometer assembly generating signals represent-ing relative positions of the wiper means and the potentiometer element.
a hollow cylindrical housing;
a piston and rod assembly reciprocal in the housing;
a walled bore extending longitudinally into the piston and rod assembly;
a support fixed with respect to the housing and received by the bore;
a hollow sleeve mounted in the housing and having means for rigidly supporting an end of the support;
a sealing plug formed within the sleeve at a position spaced apart from the support for preventing fluid communication through the sleeve;
a potentiometer assembly including an elongated potentiometer element carried on a surface of the support and wiper means slidably and resiliently engaging the potentiometer element for maintaining electrical continuity therewith; and a wiper carrier fixed for movement with the piston and rod assembly for moving the wiper means relative to the potentiometer element, the potentiometer assembly generating signals represent-ing relative positions of the wiper means and the potentiometer element.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US30033181A | 1981-09-08 | 1981-09-08 | |
| US300,331 | 1981-09-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1180916A true CA1180916A (en) | 1985-01-15 |
Family
ID=23158660
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000408261A Expired CA1180916A (en) | 1981-09-08 | 1982-07-28 | Position-sensing cylinder |
Country Status (11)
| Country | Link |
|---|---|
| EP (1) | EP0074266B1 (en) |
| JP (1) | JPS5854208A (en) |
| AT (1) | ATE18286T1 (en) |
| AU (1) | AU549902B2 (en) |
| BR (1) | BR8205185A (en) |
| CA (1) | CA1180916A (en) |
| DE (2) | DE3269407D1 (en) |
| DK (1) | DK400982A (en) |
| ES (1) | ES515508A0 (en) |
| MX (1) | MX154307A (en) |
| ZA (1) | ZA826527B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE436072B (en) * | 1983-03-22 | 1984-11-05 | Hara Ab | POTENTIOMETER DEVICE FOR DETERMINATION OF PHYSICAL HYDRAULIC PISTONS AND SIMILAR |
| DE3744254A1 (en) * | 1987-12-24 | 1989-07-13 | Integral Hydraulik Co | Linear potentiometer which is operated under oil |
| US6725761B1 (en) | 2002-09-30 | 2004-04-27 | Prince Manufacturing Corporation | Spooling device assembly for hydraulic cylinder and method of assembling same |
| US8100045B2 (en) | 2008-10-21 | 2012-01-24 | Clark Equipment Company | Hydraulic cylinder rod position sensor |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3175094A (en) * | 1962-05-24 | 1965-03-23 | Guerin Engineering Inc | Electrohydraulic actuator |
| FR1382342A (en) * | 1963-11-09 | 1964-12-18 | Mitchell Hydraulics Ltd | Improvements to mechanical control devices actuated by pressurized fluid |
| US3412391A (en) * | 1964-10-31 | 1968-11-19 | Gullick Ltd | Pressure-fluid-operated devices and means for indicating the condition thereof |
| US3726191A (en) * | 1971-02-08 | 1973-04-10 | Bunker Ramo | Electrically controlled hydraulic system and transducer therefor |
-
1982
- 1982-07-28 CA CA000408261A patent/CA1180916A/en not_active Expired
- 1982-08-20 AU AU87458/82A patent/AU549902B2/en not_active Ceased
- 1982-08-31 JP JP57151655A patent/JPS5854208A/en active Granted
- 1982-09-03 BR BR8205185A patent/BR8205185A/en unknown
- 1982-09-06 DE DE8282304667T patent/DE3269407D1/en not_active Expired
- 1982-09-06 EP EP82304667A patent/EP0074266B1/en not_active Expired
- 1982-09-06 DE DE198282304667T patent/DE74266T1/en active Pending
- 1982-09-06 ES ES515508A patent/ES515508A0/en active Granted
- 1982-09-06 AT AT82304667T patent/ATE18286T1/en active
- 1982-09-07 ZA ZA826527A patent/ZA826527B/en unknown
- 1982-09-07 MX MX194300A patent/MX154307A/en unknown
- 1982-09-08 DK DK400982A patent/DK400982A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| MX154307A (en) | 1987-06-30 |
| EP0074266A1 (en) | 1983-03-16 |
| DE74266T1 (en) | 1983-08-04 |
| BR8205185A (en) | 1983-08-16 |
| JPS5854208A (en) | 1983-03-31 |
| ES8402054A1 (en) | 1984-01-01 |
| DK400982A (en) | 1983-03-09 |
| ZA826527B (en) | 1984-04-25 |
| AU8745882A (en) | 1983-03-17 |
| ES515508A0 (en) | 1984-01-01 |
| JPH0233883B2 (en) | 1990-07-31 |
| DE3269407D1 (en) | 1986-04-03 |
| EP0074266B1 (en) | 1986-02-26 |
| ATE18286T1 (en) | 1986-03-15 |
| AU549902B2 (en) | 1986-02-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEC | Expiry (correction) | ||
| MKEX | Expiry |