(12) United States Patent
`Samuelson et al.
`
`USOO645.0048B1
`US 6,450,048 B1
`(10) Patent No.:
`Sep. 17, 2002
`(45) Date of Patent:
`
`(54) HYDRAULIC CYLINDER MONITORING
`APPARATUS
`
`(76) Inventors: Don S. Samuelson, 304 W. Myrtle St.,
`Laurens, IA (US) 50554; James D.
`Homan, 307 Court St., Ida Grove, IA
`(US) 51445; Stephen B. Jones, 2035
`Keystone Ave., Ida Grove, IA (US)
`51445
`
`(*) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(21) Appl. No.: 09/503,131
`
`Feb. 11, 2000
`(22) Filed:
`(51) Int. Cl." ................................................ G01D 21/00
`(52) U.S. Cl. ......................................... 73/866.5; 73/168
`(58) Field of Search ................................ 73/168, 866.5;
`324/207.21, 207.24, 699; 338/39, 118, 154,
`160, 184, 194, 197, 199; 92/5; 91/1
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`3,355,690 A * 11/1967 Sorensen et al.
`4,700,610 A * 10/1987 Bauer et al.
`5,150,049 A * 9/1992 Schuetz ................. 324/207.24
`5,491,633 A * 2/1996 Henry et al. ........... 324/207.24
`6,029,693 A * 2/2000 Nakanishi et al.
`OTHER PUBLICATIONS
`Copy-2 pages from a publication entitled Machine
`Design-Best-Riding Sport Utes-Second page showing a
`Stroke Smart cylinder-by Balluff Inc.; Jan. 2000.
`
`Copy-16-page brochure entitled Compact HydraulicCyl
`inders by Custom Actuator Products, Inc. of Golden Valley,
`MN, No Date.
`* cited by examiner
`Primary Examiner Robert Raevis
`(74) Attorney, Agent, or Firm-Henderson & Sturm LLP
`(57)
`ABSTRACT
`A hydraulic cylinder monitoring apparatus of a type having
`a tube with a first end and a Second end and a removable first
`cap member for Selectively closing the first end of the tube,
`the first cap member having a first opening therein. A Second
`cap member is welded to the other end of said tube, the
`Second cap having a Second opening therein. A piston is
`Sealingly disposed within the tube for movement between a
`first and a Second position between the first and Second ends
`of the tube. A rod is operatively attached to the piston and
`extends from the piston and through the first opening in the
`first cap member whereby the piston and rod can move
`together between the first and Second positions. A first
`hydraulic fluid port extends into the tube adjacent Said one
`end of the tube. A second hydraulic fluid port extends into
`the tube adjacent the Second end of the tube. A Supplemental
`cap is removably attached to the Second cap member, the
`Supplemental cap having a passageway therein. A
`transducer, including an elongated portion is removably
`fixed with respect to the Supplemental cap, and a follower
`member is removably fixed with respect to said piston
`whereby when the piston moves, the follower member
`moves along the elongated portion of the transducer. Elec
`trical wires are attached to and lead from the elongated
`portion of the transducer, the wires extending through the
`passageway in Said Supplemental cap whereby the position
`of the piston can be monitored with respect to the Supple
`mental cap by using the transducer to Sense the position of
`the follower member.
`
`8 Claims, 3 Drawing Sheets
`
`
`
`
`
`
`
`
`
`
`
`Z2
`2333.3%z a 2777777.277/ZZZ
`
`277. Z
`SN 24
`s
`SNER(4,477/7ZZZZ
`St RSG S -
`I
`LN ZZZZY
`
`
`
`
`
`NY
`
`1.
`
`
`
`
`
`5
`
`227.7272/7212YaYaN
`
`CATERPILLAR EXHIBIT 1004
`
`Page 1 of 9
`
`

`

`U.S. Patent
`
`Sep. 17, 2002
`
`Sheet 1 of 3
`
`US 6,450,048 B1
`
`
`
`
`
`
`
`glitz
`Y W.
`Yu/"gri 22
`
`M
`
`it:
`
`s
`
`Page 2 of 9
`
`

`

`U.S. Patent
`U.S. Patent
`
`Sep. 17, 2002
`Sep. 17, 2002
`
`Sheet 2 of 3
`Sheet 2 of 3
`
`US 6,450,048 B1
`US 6,450,048 B1
`
`
`
`
`
`,yA
`
`eWeLLL(ZZZILTACEERE=ae
` aeBeSNCPopLeCPLPLLLMAMLAANLLDAhahaLMLL
`
` CLLA
`NetyemSRYwe
`
`
`
`
`
`
`
`Page 3 of 9
`
`iAnN
`
`
`
`Page 3 of 9
`
`
`
`
`

`

`U.S. Patent
`U.S. Patent
`
`Sep. 17, 2002
`Sep. 17, 2002
`
`Sheet 3 of 3
`Sheet 3 of 3
`
`US 6,450,048 B1
`US 6,450,048 B1
`
`
`
`
`
`Page 4 of 9
`
`Page 4 of 9
`
`

`

`1
`HYDRAULC CYLINDER MONITORING
`APPARATUS
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`Not Applicable
`STATEMENT REGARDING FEDERALLY
`SPONSORED RESEARCH OR DEVELOPMENT
`Not Applicable
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`The present invention relates generally to hydraulic
`cylinders, and more particularly to a hydraulic cylinder
`monitoring apparatus for a welded construction-type
`hydraulic cylinder.
`2. Description of the Related Art
`In general, hydraulic cylinders with operating pressures
`less than 5000 psi can be grouped into three (3) basic
`categories: (1) Low Cost Tie-Rod Construction; (2) Welded
`Construction; and (3) Industrial (Mill Type) Tie-Rod or
`Threaded Construction. The industrial type cylinders were
`the first group to actively employ linear transducers due to
`the nature of their applications. Linear transducers are used
`to monitor the position and/or movement of a piston or
`piston rod in a hydraulic cylinder. Since these applications
`commonly included in-plant equipment, machine tools and
`highly specialized uses, design of the equipment could be
`adjusted to accommodate the additional design requirements
`driven by adding linear transducers and their impact upon
`form, fit and function of the equipment. hi other words, the
`equipment could be designed to meet the constraints asso
`ciated with incorporating a linear transducer into a cylinder.
`AS programmable Logic Controller (PLC) usage became
`more cost effective, original equipment manufacturer's
`(OEMs) producing mobile equipment have employed them
`to improve operator interface requirements (user friendly) as
`well as automate functions repeatedly used by the equip
`ment. Many functions involved the use of cylinders as linear
`actuators. The position and movement of these actuators had
`to be monitored and communicated back to the PLC if
`closed-loop feedback control was to be utilized. Cylinders
`were capable of providing this feedback via the output of
`linear transducers. Placing the transducers inside cylinders
`inside of tie-rod or threaded construction hydraulic cylinders
`have provided the most direct method of incorporating them
`as well as protecting them from damage and environmental
`degradation.
`AS the majority of cylinders used in mobile equipment are
`of the welded construction type, the challenge has been to
`find a way of installing a linear transducer into a welded
`cylinder tube and provide access for Serviceability and
`troubleshooting. Incorporating cylinders with transducers
`into mobile equipment creates additional challenges. The
`cylinder needs to be designed for the equipment rather than
`modifying the equipment design to accept the cylinder.
`Moreover, the ability to retrofit/upgrade existing equipment
`without extensive Structural change requires direct inter
`changeability between “smart” and “dumb' cylinders which
`adds further design constraints. Consequently, before the
`present invention, there existed a need to Solve the afore
`mentioned problems.
`BRIEF SUMMARY OF THE INVENTION
`The present invention relates to a hydraulic cylinder
`monitoring apparatus of a type having a tube with a first end
`
`15
`
`25
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`US 6,450,048 B1
`
`2
`and a Second end and a removable first cap member for
`Selectively closing the first end of the tube, the first cap
`member having a first opening therein. A Second cap mem
`ber is welded to the other end of said tube, the second cap
`having a Second opening therein. A piston is Sealingly
`disposed within the tube for movement between a first and
`a Second position between the first and Second ends of the
`tube. A rod is operatively attached to the piston and extends
`from the piston and through the first opening in the first cap
`member whereby the piston and rod can move together
`between the first and Second positions.
`A first hydraulic fluid port extends into the tube adjacent
`said one end of the tube. A second hydraulic fluid port
`extends into the tube adjacent the Second end of the tube. A
`Supplemental cap is removably attached to the Second cap
`member, the Supplemental cap having a passageway therein.
`A transducer, including an elongated portion is removably
`fixed with respect to the Supplemental cap, and a follower
`member is removably fixed with respect to Said piston
`whereby when the piston moves, the follower member
`moves along the elongated portion of the transducer.
`Electrical wires are attached to and lead from the elon
`gated portion of the transducer, the wires extending through
`the passageway in Said Supplemental cap whereby the posi
`tion of the piston can be monitored with respect to the
`Supplemental cap by using the transducer to Sense the
`position of the follower member.
`An object of the present invention is to provide a welded
`construction type hydraulic cylinder with an apparatus for
`monitoring the position of the piston and/or piston rod of the
`hydraulic cylinder.
`Another object of the invention is to provide a diagnostic
`device for helping to determine if an electrical problem is in
`a transducer of a monitoring System or in the wiring leading
`thereto.
`Other objects, advantages, and novel features of the
`present invention will become apparent from the following
`detailed description of the invention when considered in
`conjunction with the accompanying drawings.
`BRIEF DESCRIPTION OF THE SEVERAL
`VIEWS OF THE DRAWINGS
`FIG. 1 is a perspective view of a preferred embodiment of
`the present invention showing a portion thereof broken
`aWay,
`FIG. 2 is a partial perspective view of the piston and
`piston rod portion of the present invention with the trans
`ducer and wiring associated therewith shown;
`FIG. 3 is a schematic view of the transducer,
`FIG. 4 is also a schematic view of the transducer in the
`hydraulic cylinder of the present invention;
`FIG. 5 is a cross sectional view of the hydraulic cylinder
`of the present invention having the monitoring apparatus
`disposed therein;
`FIG. 6 is an enlarged view of the circled portion shown in
`FIG. 5;
`FIG. 7 is an exploded partial perspective view of the end
`of the hydraulic cylinder which has a cap welded thereto and
`looking at this portion from one angle thereof, and
`FIG.8 shows the structure of FIG. 7 from a different angle
`in an exploded partial perspective View.
`DETAILED DESCRIPTION OF THE
`INVENTION
`Referring now to the drawings, wherein like reference
`numerals designate identical or corresponding parts
`
`Page 5 of 9
`
`

`

`3
`throughout the several views, FIG. 1 shows a hydraulic
`cylinder apparatus (10) constructed in accordance with the
`present invention. Referring to FIG. 5, as well as to FIG. 1,
`a cylindrical tube (11) has a piston (12) and a hollow piston
`rod (13) attached thereto inside of the cylindrical tube (11).
`A first cap member (14) is threadably engaged with threads
`on one end of the cylindrical tube (11). This first cap member
`has an opening So that the rod (13) can extend therethrough
`and be movable with respect to the cap (14) and cylindrical
`tube (11). A second cap (16) is welded at weld (17) to the
`cylindrical tube (11).
`A first port (18) is on one end of the cylindrical tube (11)
`and a second tube port (19) is on the other side of piston (12)
`in the second cap member (16). The ports (18) and (19) are
`of the type on most hydraulic cylinders wherein pressure in
`one port and exhaust in the other will allow movement of the
`piston (12) in one direction and reversing the pressure and
`exhaust in these ports will cause the piston (12) and rod (13)
`to move in an opposite direction as is well known to those
`in this art.
`A transducer (21) is shown schematically in FIG.3 and is
`shown in more detail in FIG. 2 and is used to provide an
`electrical sensing of where the piston (12) and/or rod (13)
`are positioned with respect to a Supplemental cap (22).
`Resistance wand member (23) has a follower (24) with a
`brush member (25) as best shown in FIG. 6. A flange (27) is
`positioned within a recess (28) in the Supplemental cap
`member (22). This flange member (27) has a wave spring
`(29) on one side thereof and is held in place by a Snap ring
`(31) disposed in a recess (32) in the opening (28) in cap
`member (22). The resistive wand portion (23) extends into
`an elongated opening (33) within the rod (13), the rod (13)
`being attached to the piston (12) by threads (34) on the rod
`and threads (35) on the inside of the piston (12).
`Afollower (24) is attached inside of a recess (30) in piston
`(12) and a snap ring (36) holds the follower (24) in place in
`a groove (37) in the opening (35) of piston (12). Attached to
`the elongated resistance wand portion (23) is a wire (41)
`having a first resistor (42) attached thereto at the place near
`where the wire (41) extends through the flange (27) as can
`be seen in FIG. 3. The wire (41) also extends on the other
`side of the resistive wand portion (23) through the flange
`(22) to a second resistor (43). A conductive strip (44)
`asSociated with the elongated resistive want portion and
`extends through a flange (27) at wire (45). The follower (24)
`has the brush (25) thereon which is shown by the arrows in
`FIG. 3 to make contact with both the elongated resistive
`wand portion (23) and the conductive strip (44) as the
`follower (24) moves with the piston (12) along the resistive
`wand portion (23).
`The wires (41), (41a) and (45) extend through a bore (46)
`in Supplemental cap (22) and this bore (46) intersects with
`another bore (47) which extends completely through portion
`(20) of supplemental cap member (22). An access port (48)
`is disposed on one end of the bore (47) and a bore having an
`oil tight fitting (49) therein is attached in the other end of the
`bore (47) for holding the wires (41), (41a) and (42) as they
`extend out of the Supplemental cap (22).
`The access port (48) is useful to help guide the wires (41),
`(41a) and (45) in the installation and maintenance of the
`device (10). After the wires are in place, a cap closes the
`access port (48) to seal it from moisture or the like.
`Referring to FIGS. 7 and 8, it is noted that the supple
`mental cap (22) is attached to the Second cap member (16)
`by bolts (51) which extend through openings (52) in supple
`mental cap member (22) and extend into threaded openings
`
`15
`
`25
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`US 6,450,048 B1
`
`4
`(53) in the second cap member (16). Other ways of attaching
`Supplemental cap (22) to the Second cap member (16) can be
`used to make the Supplemental cap removable and still be
`within the intended scope of the present invention. FIG. 8
`shows where the cylindrical tube (11) is welded to the
`Second cap member (16) and this is an important part of the
`invention since this type of cylinder is very different from a
`tie-rod or threaded construction-type cylinder, the threaded
`construction-type cylinder having transducers as shown in
`the prior art which have a cap on each end which is threaded
`to a cylindrical tube without the utilization of a weld to
`connect the cap to the cylinder.
`FIG. 4 also shows a connector (49) which is of an oil-tight
`configuration which allows the oil to be in the bore (47), but
`which cannot exit the bore (47) because of the plugs in the
`access port (48) and because of this oil-tight connector (49).
`In operation, the hydraulic cylinder (10) of the present
`invention would be connected at ends (53) and (54) to two
`objects that needed to be selectively controlled by being
`Separated and then moved back together while the relative
`spacing is monitored by the transducer Structure (23 and 24)
`of the present invention. So looking, for example, to FIG. 5,
`it is noted that a controller, not shown, is Sensing the position
`of the piston (12) with respect to the cap (22) through the
`wires (41) and (41a) which have fixed resistors on these
`reference Supply and/or ground return wires (41) and (41a).
`Similarly, the output wire (45) is connected to such control
`ler (not shown).
`When pressurized hydraulic oil is directed into port (19)
`and the oil on the right side of the cylinder shown in FIG.
`5 is allowed to exit through port (18), the cylinder (12)
`moves to the right and the follower (24) will move with it.
`This will change the resistance as shown in FIG. 3 wherein
`the follower (24) moves along the elongated resistance wand
`portion (23). The transducer (23) and (24) shown in the
`present invention is a linear resistance type transducer but
`other types of transducers, Such as a magneto-restrictive
`type, can be used instead of the linear resistance type
`transducer (23) and (24) shown in the drawings.
`Consequently, the position of the piston (12) and/or rod (13)
`can readily be monitored as the piston (12) and rod (13)
`move from one position to another within the cylinder (11).
`It should of course be understood that the follower (24)
`could be in the rod (13) instead of in the piston (12), i.e., the
`component to which the follower (24) is connected is not
`important.
`Because the fixed resistors (42) and (43) are disposed
`within the Steel confines of the Supplemental cap (22) and its
`flange (20), there is very little chance that they can be
`damaged during the use of the device (10) of the present
`invention. The purpose of the fixed resistors (42) and (43)
`are as a diagnostic tool use-d in conjunction with the
`controller (not shown) so that, if there is a problem with the
`transducer circuit, it can be quickly determined whether it is
`within the wires (41), (41a) or (45) or whether the problem
`lies within the transducer (23) and (24) itself.
`Accordingly, it will be appreciated that the hydraulic
`cylinder control apparatus (10) of the present invention
`allows the transducer to be attached at the welded end of the
`hydraulic cylinder (10) while allowing quick and easy
`accessibility for installation and/or Servicing at a later time.
`It would not be feasible, without using the present invention,
`to Weld a cap to a cylinder tube, especially on the end where
`a transducer is positioned, without Subjecting the transducer
`inside to more heat than it can withstand. It will therefore be
`appreciated that the preferred embodiment shown herein
`
`Page 6 of 9
`
`

`

`US 6,450,048 B1
`
`15
`
`S
`does indeed accomplish the aforementioned objects.
`Obviously, many modifications and variations of the present
`invention are possible in light of the above teachings. It is
`therefore to be understood that, within the scope of the
`appended claims, the invention may be practiced otherwise
`than as Specifically described.
`We claim:
`1. Hydraulic cylinder monitoring apparatus comprising:
`a tube having a first end and a Second end;
`a removable first cap member for Selectively closing the
`first end of the tube and having a first opening therein;
`a Second cap member welded to the other end of Said tube,
`Said Seconds cap having a Second opening therein;
`a piston Sealingly disposed within Said tube for movement
`between a first and a Second position between the first
`and Second ends of the tube;
`a rod operatively attached to Said piston and extending
`from Said piston and through the first opening in the
`first cap member whereby the piston and rod can move
`together between Said first and Second positions,
`a first hydraulic fluid port extending into Said tube adja
`cent Said one end of Said tube,
`a Second hydraulic fluid port extending into Said tube
`adjacent Said Second end of the tube;
`a Supplemental cap removably attached to Said Second cap
`member, Said Supplemental cap having a passageway
`therein;
`a transducer including an elongated portion removably
`fixed with respect to Said Supplemental cap and a
`follower member removably fixed with respect to said
`piston whereby when said piston moves, said follower
`member moves along Said elongated portion of Said
`transducer; and
`electrical wires attached to and leading from Said elon
`gated portion of the transducer, Said wires extending
`through Said passageway in Said Supplemental cap
`whereby the position of Said piston can be monitored
`with respect to the Supplemental cap by using Said
`40
`transducer to Sense the position of the follower mem
`ber.
`
`25
`
`35
`
`6
`2. The apparatus of claim 1 further comprising:
`a first electrical resistor for diagnostic purposes attached
`to one of Said electrical wires at a position within Said
`passageway in Said Supplemental cap; and
`a Second electrical resistor for diagnostic purposes
`attached to another one of Said electrical wires at a
`position within Said passageway, whereby the first and
`Second resistors can be used to Sense whether the
`electrical conductivity from the first and Second resis
`tors within Said Supplemental cap and another portion
`of the wires outside of Said passageway is within
`acceptable limits, whereby having Said first and Second
`resistors within Said passageway provides a protective
`environment and permits a user to quickly determine if
`a problem is in the wires leading to Said transducer or
`in the transducer itself.
`3. The apparatus of claim 1 wherein Said Supplemental
`cap includes a receSS and a flange and Said elongated portion
`is Selectively locked into Said receSS for holding the elon
`gated portion fixed with respect to Said Supplemental cap.
`4. The apparatus of claim 1 wherein Said passageway in
`Said Supplemental cap includes a longitudinal bore and a
`bore transverse to and connected to Said longitudinal bore
`for permitting Said wires to extend from Said transducer,
`through Said longitudinal and transverse bore to the outside
`of Said Supplemental cap.
`5. The apparatus of claim 4 wherein said transverse bore
`extends completely through Said Supplemental cap, whereby
`Said wires can be threaded out of one end of the transverse
`bore and be guided to that position from the other end of said
`transverse bore.
`6. The apparatus of claim 1 wherein Said first cap member
`is threadedly engaged with threads on the first end of the
`tube.
`7. The apparatus of claim 1 wherein Said Supplemental
`cap is attached to Said Second cap member with threaded
`fasteners.
`8. The apparatus of claim 7 wherein said threaded fas
`teners are bolts extending through holes in Said Supplemen
`tal cap and into threaded holes in Said Second cap member.
`
`k
`
`k
`
`k
`
`k
`
`k
`
`Page 7 of 9
`
`

`

`UNITED STATES PATENT AND TRADEMARK OFFICE
`CERTIFICATE OF CORRECTION
`
`PATENT NO. : 6,450,048 B1
`DATED
`: September 17, 2002
`INVENTOR(S) : Don S. Samuelson et al.
`
`Page 1 of 1
`
`It is certified that error appears in the above-identified patent and that said Letters Patent is
`hereby corrected as shown below:
`
`Title page,
`Item 73, ASSignee, -- Godbersen & Smith Construction Company,
`d/b/a Gomaco Corporation
`Ida Grove, Iowa --
`
`Signed and Sealed this
`
`Eighth Day of June, 2004
`
`WDJ
`
`JON W. DUDAS
`Acting Director of the United States Patent and Trademark Office
`
`Page 8 of 9
`
`

`

`UNITED STATES PATENT AND TRADEMARK OFFICE
`CERTIFICATE OF CORRECTION
`
`PATENT NO. : 6,450,048 B1
`DATED
`: September 17, 2002
`INVENTOR(S) : Don S. Samuelson et al.
`
`Page 1 of 1
`
`It is certified that error appears in the above-identified patent and that said Letters Patent is
`hereby corrected as shown below:
`
`Title page,
`Item 73, ASSignee, insert the following:
`
`--73 ASSignee: Godbersen & Smith Construction Company,
`d/b/a Gomaco Corporation
`Ida Grove, Iowa --
`
`Signed and Sealed this
`
`Fifteenth Day of June, 2004
`
`WDJ
`
`JON W. DUDAS
`Acting Director of the United States Patent and Trademark Office
`
`Page 9 of 9
`
`