EP0074266A1 - Hydraulic cylinder with position sensor - Google Patents
Hydraulic cylinder with position sensor Download PDFInfo
- Publication number
- EP0074266A1 EP0074266A1 EP82304667A EP82304667A EP0074266A1 EP 0074266 A1 EP0074266 A1 EP 0074266A1 EP 82304667 A EP82304667 A EP 82304667A EP 82304667 A EP82304667 A EP 82304667A EP 0074266 A1 EP0074266 A1 EP 0074266A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- bar
- wiper
- bore
- hydraulic cylinder
- chamber
- 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.)
- Granted
Links
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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
Definitions
- This invention relates to a hydraulic cylinder with a position sensor comprising a bar fixed to the closed end of the cylinder and extending into a bore in the piston rod, a potentionmeter element on a support surface of the bar, and a wiper, carrier attached to the piston rod, with a wiper which moves along the potentiometer element as the piston rod moves in the cylinder.
- the wiper contacts are suspended in the fluid escape path, allowing flow forces to vibrate or bend the contact leaf, resulting in operating noise or loss of signal.
- the support bar is supported only at one by a plastics sealing element which is subject to mechanical stress and failures.
- the object of the present invention is to overcome these problems and the invention is characterised in that the support bar has a cross-section such as to slidably engage the wall of the bore, thereby to align the support bar relative to the wiper carrier.
- the invention in another respact is characterised in that the wiper arm is so shaped in conjunction with the bar as to prevent fluid flow in the vicinity of the wiper when the piston rod moves relative to the cylinder.
- 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 vibration. Another advantage of the preferred embodiment is that it provides a potentiometer element support rod with good rigidity and low cross-sectional area, and which is mechanically supported along the length of its engagement with the cylinder rod bore.
- a further advantage of the preferred construction is that it provides a position-sensing cylinder with an improved fluid pressure seal which is spaced apart from the support rod and thus, not subject to mechanical stress caused by the support of the support rod.
- the support rod is a T-section support'rod with one end welded or fixed to a hollow metallic sleeve which is press fitted into a fitting which is screwed into the closed end of the cylinder.
- a ceramic plug seals the interior of the sleeve but provides no support for and is separate from the support rod.
- Further support for the potentionmeter support rod is provided- by the sliding engagement between its edges and the wall of the rod bore within which the support rod reciprocates.
- a wiper carrier co-operates with the bore wall and the potentiometer support to prevent fluid flow in the vicinity of the flexible wiper contacts.
- a 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 screwed into the rod 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 at its closed end for receiving a steel outer transducer fitting 36.
- the fitting 36 has an annular flange 38 for butting against a corresponding housing shoulder 40.
- An O-ring 42 maintains a fluid- tight seal between the fitting 36 and the housing 12.
- the fitting 36 also includes a stepped axial bore 44 extending therethrough.
- a steel terminal sleeve 46 is press fitted into the fitting bore 44.
- the sleeve 46 has an annular groove 48 which receives a back-up ring 50 and an 0-ring 52 for maintaining a fluid seal between the fitting 36 and the terminal 46.
- a plug of ceramic material 54 is formed in the hollow interior of the sleeve 46 to form a hermatic seal.
- the sleeve 46 is formed as a separate piece from the fitting 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 exposed if the fitting 36 and the terminal 46 were a single piece.
- a steel support bar 60 extends into the bore 22 from an end 62 received by and welded to the sleeve 46.
- 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 that described in US. Patent No 3,726,191, have supported the transducer support element by press fitting the support into a plastics insulating sleeve, which is, in turn,received by a metallic threaded fitting.
- the transducer support is less rigidly supported at its supported end and the plastics insulating material is subject to stress failures, such as cracking, which then degrades its sealing properties.
- the ceramicseal 54 is subject to very little mechanical stress caused by supporting the support 60. Instead, the ceramic seal 54 need only withstand the hydraulic pressures which it is designed to withstand, with the result that the embodiment of the invention has increased integrity with respect to.-fluid pressure sealing.
- the support bar 60 has a substantially T-shaped cross-section (as best seen in Figs, 3 and 4) formed by a cross piece 64 and from which perpendicularly extends a stiffening web 66 perpendicular thereto.
- the face of the cross piece 64 which is opposite the web 66 forms a planar support surface 68.
- a circular edged notch 70 is formed in the end 62 of the support "60, as best seen in Figs. 2 and 4.
- the cross piece 64 and the web 66 divide the bore 22 into three fluid chambers 65, 67 and 69, of which chambers 65 and 67 are visible in Fig 2.
- curved outer edges 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 subject if it were cantilevered, ie, supported merely at one end.
- a resistance or potentiometer assembly 72 is placed on the planar support surface 68 of the cross piece 64.
- the assembly includes an electrically insulating base 74 fixed to the support surface 68 and which may be formed of material such as "Kapton", ( a Trade Mark of DuPont ) .
- the assembly 72 also includes a conductive plastics potentiometer element 76, of which the largest elongated central portion thereof is laid directly upon the insulating base 74.
- the ends 78 and 80 of the potentiometer element are overlaid on to 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..
- the • Conductive ground strip 82 terminates at edge 83, under the end 78 of the potentiometer element 76, as shown in dashed line Fig.5.
- a conductor 86 is soldered to the other end of the ground strip 82.
- the 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 the power strip 84 is joined via a solder joint to a conductor 88.
- a metallic or electrical conductive commutator strip 90 extends from an edge indicated by reference numberal 92 to an end 94 to which is soldered to a conductor 96.
- An overlay strip 98 of conductive plastics material is positioned on top of the commutator strip 90 and extends from edge 99 to an edge also indicated by reference numberal 92.
- the major portion of the power strip 84 is separated from the commutator strip 90 by the middle or potentiometer strip 76 to reduce the possibility of metallic particles froming undesirable short circuit connections between the power strip 84 and the commutator strip 90.
- the transducer 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.
- 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 cup 46 and the ceramic seal 54 to respective connector terminals 100,102 and 104, two of which are visible in Fig. 2.
- a conventional female plug-type connector may be coupled to the connector terminals 100,102 and 104.
- 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 cylicndrical body 112 of an insulating material such as glass-reinforced nylon with an annular rebate l14 in one end thereof.
- the rebate 114 registers with the ridge 28 only when the carrier 110 is properly mounted in the bore port;-on 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 web 116 extends inwardly from a portion of the body 112.
- a two- pronged conductive wiper 118 is embedded in and supported by the web 116 so that prongs 120 and 122 resiliently and slidably engage the surfaces of the plastics conductive strip 98 above commutator strip 90 and the potentiometer element portion 76, respectively.
- the wiper 118 is exposed to the fluid in the chamber 65.
- the prongs 120 and 122 have multiple fingers.
- a rectangular recess 124 is formed in the inner surface 125 of the carrier web 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 the snap ring 126 and a resilient wave washer 128.
- a voltage is applied across terminals 102 and 100 to apply a. corresponding voltage across the resistance element 76.
- the wiper 118 moves with the piston 16 and rod 18 and with respect to the support 60 and the transducer element 72.
- the voltage which the wiper 118 taps off varies from ground potential to approximately the voltage at the power strip 84, depending upon the longitudinal position of the wiper l18 relative to the resistance element 76.
- the voltage on the wiper 118 is communicated to the exterior of the cylinder housing 12 via the commutator strips 98 and 90, conductor 96 and connector terminal 104, from where it can be monitored to indicate the position of cylinder 10.
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)
- Characterised By The Charging Evacuation (AREA)
- Looms (AREA)
- Devices For Conveying Motion By Means Of Endless Flexible Members (AREA)
- Fluid-Pressure Circuits (AREA)
- Reciprocating Pumps (AREA)
- Valve Device For Special Equipments (AREA)
- Body Structure For Vehicles (AREA)
- Forklifts And Lifting Vehicles (AREA)
Abstract
Description
- This invention relates to a hydraulic cylinder with a position sensor comprising a bar fixed to the closed end of the cylinder and extending into a bore in the piston rod, a potentionmeter element on a support surface of the bar, and a wiper, carrier attached to the piston rod, with a wiper which moves along the potentiometer element as the piston rod moves in the cylinder.
- In hydraulic controls technology, it is often desirable to obtain feedback signals representing the operating position of a hydraulic cylinder. US. Patent No.3,726,191 discloses"one solution to this problem. A resistance and conductor element support bar-are reciprocably received in a piston rod bore. A conductive wiper assembly is carried for movement with the piston and rod. However, the known transducer construction 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 escape path for displaced hydraulic fluid is so large as to prevent its use in many hydraulic cylinders where compact size is required. Furthermore, the wiper contacts are suspended in the fluid escape path, allowing flow forces to vibrate or bend the contact leaf, resulting in operating noise or loss of signal. Finally, the support bar is supported only at one by a plastics sealing element which is subject to mechanical stress and failures.
- The object of the present invention is to overcome these problems and the invention is characterised in that the support bar has a cross-section such as to slidably engage the wall of the bore, thereby to align the support bar relative to the wiper carrier.
- The invention in another respact is characterised in that the wiper arm is so shaped in conjunction with the bar as to prevent fluid flow in the vicinity of the wiper when the piston rod moves relative to the cylinder.
- 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 vibration. Another advantage of the preferred embodiment is that it provides a potentiometer element support rod with good rigidity and low cross-sectional area, and which is mechanically supported along the length of its engagement with the cylinder rod bore.
- A further advantage of the preferred construction is that it provides a position-sensing cylinder with an improved fluid pressure seal which is spaced apart from the support rod and thus, not subject to mechanical stress caused by the support of the support rod.
- Thus in the preferred embodiment, the support rod is a T-section support'rod with one end welded or fixed to a hollow metallic sleeve which is press fitted into a fitting which is screwed into the closed end of the cylinder. A ceramic plug seals the interior of the sleeve but provides no support for and is separate from the support rod. Further support for the potentionmeter support rod is provided- by the sliding engagement between its edges and the wall of the rod bore within which the support rod reciprocates. A wiper carrier co-operates with the bore wall and the potentiometer support to prevent fluid flow in the vicinity of the flexible wiper contacts. The invention will be described in more detail, by way of example, with reference to the accompanying drawings, in which:-,
- Fig 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 the cylinder with the potentiometer assembly fitted,
- Fig 3 is a view taken on line 3 - 3 of Fig 2,
- Fig 4 is a view taken on line 4 -4 of Fig 2,
- Fig 5 is a top view of the terminal piece and the transducer support of the potentiometer assembly,
- Figs 6a to 6d are unscaled sectional views taken on lines A-A, B-B, C-C and D-D respectively of Fig 5, and
- Fig 7 is an end view of the wiper carrier of the assembly.
- A
hydraulic cylinder 10 includes ahousing 12 having a hollowcylindrical barrel portion 14 within which reciprocates apiston 16 connected to arod 18. A rod-receivingcap 20 is screwed into the rod end of thehousing 12. A blind stepped bore 22 extends into thepiston 16 and therod 18. As best seen in Fig 2, thebore 22 has alarge diameter portion 24 with asnap ring groove 26 therein and anannular ridge 28 at one end, asmaller diameter portion 30 and anannular shoulder 32 extending therebetween. - The
housing 12 includes a threadedaxial bore 34 at its closed end for receiving a steel outer transducer fitting 36. Thefitting 36 has anannular flange 38 for butting against acorresponding housing shoulder 40. An O-ring 42 maintains a fluid- tight seal between the fitting 36 and thehousing 12. thefitting 36 also includes a steppedaxial bore 44 extending therethrough. - A
steel terminal sleeve 46 is press fitted into thefitting bore 44. Thesleeve 46 has anannular groove 48 which receives a back-upring 50 and an 0-ring 52 for maintaining a fluid seal between thefitting 36 and theterminal 46. A plug ofceramic material 54 is formed in the hollow interior of thesleeve 46 to form a hermatic seal. Thesleeve 46 is formed as a separate piece from thefitting 36 so that, when theceramic material 54 is heated within theterminal 46, thefitting 36 is not degraded by the high temperatures to which it would otherwise be exposed if thefitting 36 and theterminal 46 were a single piece. - A
steel support bar 60 extends into thebore 22 from anend 62 received by and welded to thesleeve 46. Thus, theend 62 of thesupport 60 is rigidly supported with respect to thehousing 12 bymetallic pieces support 60. Instead, theceramic seal 54 need only withstand the hydraulic pressures which it is designed to withstand, with the result that the embodiment of the invention has increased integrity with respect to.-fluid pressure sealing. - The
support bar 60 has a substantially T-shaped cross-section (as best seen in Figs, 3 and 4) formed by across piece 64 and from which perpendicularly extends astiffening web 66 perpendicular thereto. The face of thecross piece 64 which is opposite theweb 66 forms aplanar support surface 68. A circularedged notch 70 is formed in theend 62 of the support "60, as best seen in Figs. 2 and 4. - The
cross piece 64 and theweb 66 divide thebore 22 into threefluid chambers chambers outer edges support 60 slidably engage the wall of thebore 22. This engagement adds rigidity to thesupport 60 and helps to prevent deformation of thesupport 60 and reduces vibration to which thesupport 60 would be subject if it were cantilevered, ie, supported merely at one end. - As best seen in Figs 5 and 6a-d, a resistance or
potentiometer assembly 72 is placed on theplanar support surface 68 of thecross piece 64. The assembly includes an electrically insulatingbase 74 fixed to thesupport surface 68 and which may be formed of material such as "Kapton", ( a Trade Mark of DuPont ) . - The
assembly 72 also includes a conductiveplastics potentiometer element 76, of which the largest elongated central portion thereof is laid directly upon theinsulating base 74. Theends power strips potentiometer element 76 terminates atedges Conductive ground strip 82 terminates atedge 83, under theend 78 of thepotentiometer element 76, as shown in dashed line Fig.5. Aconductor 86 is soldered to the other end of theground strip 82. Theconductive power strip 84 terminates at anedge 85 underend 80 of thepotentiometer element 76, as also shown in dashed line in Fig. 5. The overlaps between theconductive strips power strip 84 is joined via a solder joint to aconductor 88. A metallic or electricalconductive commutator strip 90 extends from an edge indicated by reference numberal 92 to anend 94 to which is soldered to aconductor 96. Anoverlay strip 98 of conductive plastics material is positioned on top of thecommutator strip 90 and extends fromedge 99 to an edge also indicated by reference numberal 92. The major portion of thepower strip 84 is separated from thecommutator strip 90 by the middle orpotentiometer strip 76 to reduce the possibility of metallic particles froming undesirable short circuit connections between thepower strip 84 and thecommutator strip 90. Also note that thetransducer element 72 is not received in a recess or channel in thesupport 60, but rather is positioned on top of theplanar support surface 68. The absence of a recess or channel reduces the likelihood of metallic particles forming undesirable short circuit connections between thesupport 60 and the outer edges of thepower strip 84 and thecommutator strip 90. For clarity, the thicknesses of the various strips in Figs. 6a-d are exaggerated. Theconductors notch 70, theterminal cup 46 and theceramic seal 54 to respective connector terminals 100,102 and 104, two of which are visible in Fig. 2. A conventional female plug-type connector may be coupled to the connector terminals 100,102 and 104. - A
wiper carrier 110 is received bybore portion 24 of thebore 22, as best seen in Fig, 2. Thewiper carrier 110 has a generallycylicndrical body 112 of an insulating material such as glass-reinforced nylon with an annular rebate l14 in one end thereof. Therebate 114 registers with theridge 28 only when thecarrier 110 is properly mounted in the bore port;-on 24, otherwise, theannular ridge 28 will prevent thecarrier 110 from being inserted far enough intobore portion 24 to allow insertion ofsnap ring 126 intosnap ring groove 26. Awiper support web 116 extends inwardly from a portion of thebody 112. A two- prongedconductive wiper 118 is embedded in and supported by theweb 116 so thatprongs 120 and 122 resiliently and slidably engage the surfaces of the plasticsconductive strip 98 abovecommutator strip 90 and thepotentiometer element portion 76, respectively. Thewiper 118 is exposed to the fluid in thechamber 65. As best seen in Fig. 7, theprongs 120 and 122 have multiple fingers. Arectangular recess 124 is formed in theinner surface 125 of thecarrier web 116 so that theinner surface 125 closely registers with thesurface 68 of thesupport element 60 and with thetransducer element 72. Thecarrier 110 is coupled for movement with therod 18 andpiston 16 between thesnap ring 126 and aresilient wave washer 128. - When the
piston 16 androd 18 move back and forth with respect to he housing 12 and thesupport 60, fluid flows into and out of thechamber 65, around theend 129 of thesupport 60 and viachambers inner surface 125 andsurface 68 andelement 72 substantially prevents fluid flow into or out of thechamber 65 via thewiper carrier 110, thus reducing flow-induced turbulence in the vicinity of thewiper 118. This reduced turbulence prevents turbulence induced vibrations in thewiper 118 which could otherwise introduce noise into the signals picked up by thewiper 118. - In operation, a voltage is applied across
terminals resistance element 76. As thepiston 16 androd 18 move back and forth within thehousing 12, thewiper 118 moves with thepiston 16 androd 18 and with respect to thesupport 60 and thetransducer element 72. Thus, the voltage which thewiper 118 taps off varies from ground potential to approximately the voltage at thepower strip 84, depending upon the longitudinal position of the wiper l18 relative to theresistance element 76. The voltage on thewiper 118 is communicated to the exterior of thecylinder housing 12 via the commutator strips 98 and 90,conductor 96 andconnector terminal 104, from where it can be monitored to indicate the position ofcylinder 10.
Claims (11)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT82304667T ATE18286T1 (en) | 1981-09-08 | 1982-09-06 | HYDRAULIC CYLINDER WITH POSITION SENSOR. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US30033181A | 1981-09-08 | 1981-09-08 | |
US300331 | 1981-09-08 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0074266A1 true EP0074266A1 (en) | 1983-03-16 |
EP0074266B1 EP0074266B1 (en) | 1986-02-26 |
Family
ID=23158660
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP82304667A Expired EP0074266B1 (en) | 1981-09-08 | 1982-09-06 | Hydraulic cylinder with position sensor |
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) | ES8402054A1 (en) |
MX (1) | MX154307A (en) |
ZA (1) | ZA826527B (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1984003763A1 (en) * | 1983-03-22 | 1984-09-27 | Hara Ab | Potentiometer device for determining the position of hydraulic pistons and the like |
US8100045B2 (en) | 2008-10-21 | 2012-01-24 | Clark Equipment Company | Hydraulic cylinder rod position sensor |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
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 |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR1382342A (en) * | 1963-11-09 | 1964-12-18 | Mitchell Hydraulics Ltd | Improvements to mechanical control devices actuated by pressurized fluid |
US3175094A (en) * | 1962-05-24 | 1965-03-23 | Guerin Engineering Inc | Electrohydraulic actuator |
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 EP EP82304667A patent/EP0074266B1/en not_active Expired
- 1982-09-06 ES ES515508A patent/ES8402054A1/en not_active Expired
- 1982-09-06 DE DE8282304667T patent/DE3269407D1/en not_active Expired
- 1982-09-06 DE DE198282304667T patent/DE74266T1/en active Pending
- 1982-09-06 AT AT82304667T patent/ATE18286T1/en active
- 1982-09-07 MX MX194300A patent/MX154307A/en unknown
- 1982-09-07 ZA ZA826527A patent/ZA826527B/en unknown
- 1982-09-08 DK DK400982A patent/DK400982A/en not_active Application Discontinuation
Patent Citations (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 |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1984003763A1 (en) * | 1983-03-22 | 1984-09-27 | Hara Ab | Potentiometer device for determining the position of hydraulic pistons and the like |
EP0128881A2 (en) * | 1983-03-22 | 1984-12-19 | Hara Production Aktiebolag | Potentiometer device for determining the position of hydraulic pistons and the like |
EP0128881A3 (en) * | 1983-03-22 | 1987-06-03 | Hara Production Aktiebolag | Potentiometer device for determining the position of hydraulic pistons and the like |
US8100045B2 (en) | 2008-10-21 | 2012-01-24 | Clark Equipment Company | Hydraulic cylinder rod position sensor |
Also Published As
Publication number | Publication date |
---|---|
ES515508A0 (en) | 1984-01-01 |
DE74266T1 (en) | 1983-08-04 |
EP0074266B1 (en) | 1986-02-26 |
MX154307A (en) | 1987-06-30 |
DE3269407D1 (en) | 1986-04-03 |
DK400982A (en) | 1983-03-09 |
ZA826527B (en) | 1984-04-25 |
ES8402054A1 (en) | 1984-01-01 |
BR8205185A (en) | 1983-08-16 |
JPS5854208A (en) | 1983-03-31 |
AU8745882A (en) | 1983-03-17 |
CA1180916A (en) | 1985-01-15 |
ATE18286T1 (en) | 1986-03-15 |
JPH0233883B2 (en) | 1990-07-31 |
AU549902B2 (en) | 1986-02-20 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Designated state(s): AT BE CH DE FR GB IT LI NL SE |
|
ITCL | It: translation for ep claims filed |
Representative=s name: LENZI & C. |
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