US3368789A - Electromagnetic valve - Google Patents

Electromagnetic valve Download PDF

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Publication number
US3368789A
US3368789A US423618A US42361864A US3368789A US 3368789 A US3368789 A US 3368789A US 423618 A US423618 A US 423618A US 42361864 A US42361864 A US 42361864A US 3368789 A US3368789 A US 3368789A
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US
United States
Prior art keywords
pole
armature
shaped
magnet
valve
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 - Lifetime
Application number
US423618A
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English (en)
Inventor
Martin Helmut
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Concordia Maschinen und Elektrizitats GmbH
Original Assignee
Concordia Maschinen und Elektrizitats GmbH
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Concordia Maschinen und Elektrizitats GmbH filed Critical Concordia Maschinen und Elektrizitats GmbH
Application granted granted Critical
Publication of US3368789A publication Critical patent/US3368789A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K31/00—Actuating devices; Operating means; Releasing devices
    • F16K31/02—Actuating devices; Operating means; Releasing devices electric; magnetic
    • F16K31/06—Actuating devices; Operating means; Releasing devices electric; magnetic using a magnet, e.g. diaphragm valves, cutting off by means of a liquid
    • F16K31/0644—One-way valve
    • F16K31/0655—Lift valves
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/06—Electromagnets; Actuators including electromagnets
    • H01F7/08—Electromagnets; Actuators including electromagnets with armatures
    • H01F7/16—Rectilinearly-movable armatures
    • H01F7/1607—Armatures entering the winding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/06—Electromagnets; Actuators including electromagnets
    • H01F7/08—Electromagnets; Actuators including electromagnets with armatures
    • H01F7/16—Rectilinearly-movable armatures
    • H01F7/1638—Armatures not entering the winding

Definitions

  • the present invention relates to an electromagnetically operated valve which is provided with a fixed pot-shaped magnetic element, the central and outer wall parts of which form magnetic poles, and with a movable armature of an inverted T-shaped cross section, the central arm of which projects into the pot-shaped element.
  • the present invention further provides that the opposite pole surfaces of the magnet are made of a conical shape. This has the advantage that, when the armature is pulled up, the width of the air gaps is reduced and the armature will thereby also be accurately centered Within the fixed element of the magnet.
  • the central arm of the T-shaped armature may also be made of a short length and the'central magnetic pole of the fixed magnetic element may be downwardly extended.
  • the armature merely in the form of a flat disk and to make the fixed magnet of a double U-shaped cross section. In such a case, it is, however, necessary to provide additional centering means for insuring that the movement of the armature will occur centrally to the fixed element of the magnet.
  • Another feature of the invention which is contained in a very preferred embodiment thereof consists in providing the core of the fixed magnetic element with a central conical recess into which the central arm of the arm of the armature projects which forms a frustum.
  • the rim of the fixed magnetic element may project inwardly and form a magnetic shunt ring, and the conical pole surface which is provided on this rim or ring may be made of a considerably greater width than the associated opposite pole surface which is provided on the armature disk from which the frustum projects.
  • the outer wall of the fixed pot-shaped element of the magnet may be formed by the magnet housing.
  • a magnet may be very easily assembled by placing the inwardly projecting rim of the fixed element of the magnet directly upon the valve body, by holding the different parts of the fixed element together by means of a compressed elastic ring, and by then securing the magnet housing to the valve body, for example, by screws.
  • the outer wall of the fixed pot-shaped element of the magnet may be provided in the form of a tubular casing, the lower end of which is inserted into a cylindrical recess in the upper end of the valve body so as to be accurately centered, while the upper part of this casing is enclosed by a housing of noncorrosive material.
  • the housing may also be provided with an inner flange or projection for holding the different parts of the fixed element of the magnet together.
  • FIGURE 1 shows one half of a valve according to the invention which is provided within a housing which is not fully noncorrosive; while FIGURE 2 shows one half of a valve according to the invention which is mounted within a housing which consists of a noncorrosive and nonmagnetic material.
  • the electromagnetic valve according to the invention as illustrated in FIGURE 1 comprises a valve body 1 which is preferably made of aluminum and has a valve inlet 2 and a valve outlet 3 which, when the valve is open, communicate with each other through the opening of the valve seat 4.
  • This valve seat 4 is surrounded by an inlet chamber 5 which may, for example, be cut into the valve body 1 from the upper side.
  • the valve body 1 carries the lower magnetic shunt ring 6, the lower conical surface of which engages upon the corresponding upper conical surface of the valve body and is thus properly centered relative thereto.
  • An outer annular groove 7 around the upper conical surface of the valve body contains a sealing ring 8.
  • the fixed element of the magnet consists of the lower magnetic shunt ring 6, the magnet housing 9, the upper magnetic shunt ring 10, and the magnet core 11 and has a pot-shaped form with an inwardly projecting rim.
  • This fixed element of the magnet is energized by an annular coil 13 which rests on a brass ring 12 and may, if properly insulated, be mounted directly on the magnet core 11.
  • the upper shunt ring 10 carries an insulating disk 14 which is separated from the upper wall or cover of the magnet housing by a ring 15 of elastic material.
  • the elastic ring 15 will be compressed, whereby the fixed parts of the magnet will be firmly held together and the magnet housing will be tightly closed toward the outside.
  • the insulating disk 14 supports a coil terminal 17 from which the electric connecting cable leads to the outside through an airtight cable inlet, not shown.
  • the valve according to the invention is preferably operated with direct current.
  • the armature 18 of the magnet has substantially an inverted T-shape and serves as the support of the valve ring 19 which consists of a well-sealing elastic material.
  • Armature 18 consists of the central bar 20 of the inverted T which has the shape of a frustum, of an armature disk 21 which forms the cross bar of the inverted T and has a conical outer edge, and of a bolt 22 with a fiat head 23 which secures the valve ring 19 to the armature.
  • the pole surface on the shunt ring 6 has a considerably greater width than the opposite pole surface on the armature disk 21.
  • the bolt head 23 may also be provided with at least one slidable guide number 24 for maintaining the armature in the proper position in the event that the pull of the magnet is too eccentric.
  • the magnet core 11 is provided with a conical recess of a shape in accordance with that of the frustum 20, and the bottom of this conical recess has a cylindrical blind hole 25 into which one end of a brass bushing 26 is pressed.
  • the outer part of bushing 26 serves as a guide for the armature 18, and at the inside this bushing contains a return spring 27 which acts at one end upon the bottom of a blind hole in the frustum 2t) and at the other end upon the magnet core 11 so that, when the magnet is not energized, the armature 18 together with its valve ring 19 will be pressed firmly upon the valve seat 4 and the latter will thus always be closed tightly.
  • the magnetic circuit which is formed by the fixed magnet parts 11, 10, 9, and 6 and the armature parts 21 and 20 is interrupted by air gaps between the parts 20 and 11 and the parts 6 and 21.
  • the particular design and construction of the parts of the magnetic circuit as provided in accordance with the invention is intended for the purpose of reducing the width of the two air gaps when the armature is pulled up and of thus considerably increasing the power of the magnetic valve.
  • the new magnetic valve will therefore operate properly even though the flow of the fluid to be controlled has a relatively high pressure.
  • the electromagnetic valve according to the modification of the invention as illustrated in FIGURE 2 differs from the valve according to FIGURE 1 primarily by the fact that in place of a magnet housing 9, as shown in FIGURE 1, it is provided with a magnetic tubular casing 28 which is enclosed by a housing 29 of a noncorrosive material, for example, aluminum.
  • a noncorrosive material for example, aluminum.
  • the magnet housing 9 according to FIGURE 1 could also be made of noncorrosive magnetic steel, such a structure would be much more expensive than that as illustrated in FIG- URE 2.
  • the lower magnetic shunt ring 60 according to FIG- URE 2 is mounted together with the lower end of the inner casing 28 in a cylindrical recess 30 in the upper end of the valve body 1a.
  • Housing 29 is closed at its upper end by a cover 31 which may likewise consist of aluminum.
  • the different parts of this structure are held together in the proper relation to each other by an inner flange 32 on the housing 29 and are secured to each other by means of screws, not shown.
  • the fixed parts 11, 1t ⁇ , 28, and 6a of the magnet according to FIGURE 2 may also be integrally connected to each other and be made in the form of a single pressed piece of magnetizable material, and the coil which is separately made may then he slipped over the magnet core 11.
  • An electromagnetic valve comprising a fixed substantially pot-shaped magnetizable element, a field coil for energizing said element, and a movable armature of a substantially T-shaped cross section having a diskshaped member and a central member projecting from said disk-shaped member and movable into the open side of said pot-shaped element when said fixed element is energized, the outer surfaces of said central and diskshaped members together forming pole surfaces of one magnetic pole, and the central part and the rim of said fixed element together forming pole surfaces of the other magnetic pole, each of said pole surfaces being conicallyshaped and disposed in an opposed, substantially parallel relationship with a pole surface of the opposite pole, said comically-shaped opposed pole surfaces defining therebetween at least two air gaps, whereby the size of said air gaps will be reduced when said fixed element is energized and said armature is attracted thereby.
  • said fixed magnetizable element has a central mag net core projecting from its bottom, said magnet core having a conical recess, said central member of said armature having a frustum shape and normally projecting centrally into said conical recess but spaced from the surface thereof by one of said air gaps.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Magnetically Actuated Valves (AREA)
US423618A 1963-11-09 1964-11-03 Electromagnetic valve Expired - Lifetime US3368789A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEC0031359 1963-11-09

Publications (1)

Publication Number Publication Date
US3368789A true US3368789A (en) 1968-02-13

Family

ID=7019793

Family Applications (1)

Application Number Title Priority Date Filing Date
US423618A Expired - Lifetime US3368789A (en) 1963-11-09 1964-11-03 Electromagnetic valve

Country Status (4)

Country Link
US (1) US3368789A (de)
CH (1) CH418073A (de)
DE (1) DE1464526A1 (de)
NL (1) NL6412414A (de)

Cited By (33)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3424429A (en) * 1965-10-23 1969-01-28 Sterer Eng & Mfg Co Solenoid operated valve
US3506085A (en) * 1967-08-28 1970-04-14 Mobil Oil Corp Pneumatic acoustic source employing electromagnetic controlled valve
US3982554A (en) * 1974-04-25 1976-09-28 Tekyo Keiki Company Limited Electromagnetic flapper valve
US4238110A (en) * 1979-07-23 1980-12-09 Colt Industries Operating Corp. Electromagnetic fuel metering valve assembly
EP0024909A1 (de) * 1979-08-23 1981-03-11 Ledex, Inc. Solenoide
US4647008A (en) * 1984-08-21 1987-03-03 Toyota Jidosha Kabushiki Kaisha Solenoid valve for hydraulic control
US4946103A (en) * 1987-12-02 1990-08-07 Ganser-Hydromag Electronically controlled fuel injector
US5064166A (en) * 1990-09-20 1991-11-12 Ford Motor Company Solenoid valve with high flow capacity and low energy consumption
US20060027269A1 (en) * 2004-08-06 2006-02-09 Neff Robert H Rapid response solenoid for electromagnetic operated valve
US20060181144A1 (en) * 2005-02-16 2006-08-17 Bendix Commercial Vehicle Systems, Llc Solenoid armature with integrated spherical soft seal
US20090200502A1 (en) * 2008-02-08 2009-08-13 Schaeffler Kg Electromagnetic actuator for a hydraulic directional control valve
US20100219361A1 (en) * 2006-05-16 2010-09-02 Mondragon Componentes, S. Coop Rotary gas tap with an integral electromagnetic valve
WO2016073966A1 (en) * 2014-11-07 2016-05-12 Dawn Equipment Company Agricultural system
US20160356393A1 (en) * 2015-06-05 2016-12-08 Xiamen Koge Micro Tech Co., Ltd. Solenoid valve and solenoid valve device
US9615497B2 (en) 2014-02-21 2017-04-11 Dawn Equipment Company Modular autonomous farm vehicle
US9668398B2 (en) 2014-02-05 2017-06-06 Dawn Equipment Company Agricultural system for field preparation
US9788472B2 (en) 2010-09-15 2017-10-17 Dawn Equipment Company Row unit for agricultural implement
US9848522B2 (en) 2014-11-07 2017-12-26 Dawn Equipment Company Agricultural system
US9861022B2 (en) 2013-02-01 2018-01-09 Dawn Equipment Company Agricultural apparatus with hybrid single-disk, double-disk coulter arrangement
US10251324B2 (en) 2011-07-01 2019-04-09 Charles H. Martin Agricultural field preparation device
US10444774B2 (en) 2014-11-07 2019-10-15 Dawn Equipment Company Agricultural system
US10477760B2 (en) 2015-12-28 2019-11-19 Underground Agriculture, LLC Agricultural organic device for weed control
US10506755B2 (en) 2010-09-15 2019-12-17 Dawn Equipment Company Agricultural systems
US10548260B2 (en) 2017-05-04 2020-02-04 Dawn Equipment Company System for automatically setting the set point of a planter automatic down pressure control system with a seed furrow sidewall compaction measurement device
US10582653B2 (en) 2014-11-07 2020-03-10 Dawn Equipment Company Agricultural planting system with automatic depth control
US10645865B2 (en) 2017-05-04 2020-05-12 Dawn Equipment Company Agricultural row unit with automatic control system for furrow closing device
US10721855B2 (en) 2014-02-05 2020-07-28 Dawn Equipment Company Agricultural system for field preparation
US10980174B2 (en) 2015-12-28 2021-04-20 Underground Agriculture, LLC Agricultural mowing device
US11006563B2 (en) 2017-05-04 2021-05-18 Dawn Equipment Company Seed firming device for improving seed to soil contact in a planter furrow with feature designed to prevent the buildup of soil on the outer surfaces by discharging pressurized fluid
US11083134B2 (en) 2015-12-28 2021-08-10 Underground Agriculture, LLC Agricultural inter-row mowing device
US11197411B2 (en) 2014-11-07 2021-12-14 Dawn Equipment Company Agricultural planting system with automatic depth control
US12171152B2 (en) 2010-09-15 2024-12-24 Deere & Company System and method for adaptively controlling depth of ground-engaging planting row unit using forward sensor that measures residue ahead of row unit
US12389816B2 (en) 2013-02-04 2025-08-19 Deere & Company Agricultural systems

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DD114660A1 (de) * 1974-04-08 1975-08-12
DE2933545A1 (de) * 1979-08-18 1981-03-26 Festo Kg, 73734 Esslingen Magnetventil
DE3070590D1 (en) * 1980-11-06 1985-06-05 Jacobs Mfg Co Improved solenoid
DE3505169C2 (de) * 1985-02-15 1995-04-06 Mannesmann Ag Betätigungsmagnet
JP2015152156A (ja) * 2014-02-19 2015-08-24 株式会社テージーケー 電磁弁

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1767725A (en) * 1928-02-23 1930-06-24 Magnetic Organ Action Company Electromagnet
US2121657A (en) * 1936-02-01 1938-06-21 James B Fisher Electromagnetic control means
US2543455A (en) * 1946-01-03 1951-02-27 Skinner Chuck Company Valve
US2735047A (en) * 1956-02-14 Antivibration solenoid structure
US2838068A (en) * 1951-02-10 1958-06-10 Gen Controls Co Electromagnetic valve
US3168242A (en) * 1962-11-05 1965-02-02 Eldima A G Electromagnetically operated temperature regulating system

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2735047A (en) * 1956-02-14 Antivibration solenoid structure
US1767725A (en) * 1928-02-23 1930-06-24 Magnetic Organ Action Company Electromagnet
US2121657A (en) * 1936-02-01 1938-06-21 James B Fisher Electromagnetic control means
US2543455A (en) * 1946-01-03 1951-02-27 Skinner Chuck Company Valve
US2838068A (en) * 1951-02-10 1958-06-10 Gen Controls Co Electromagnetic valve
US3168242A (en) * 1962-11-05 1965-02-02 Eldima A G Electromagnetically operated temperature regulating system

Cited By (51)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3424429A (en) * 1965-10-23 1969-01-28 Sterer Eng & Mfg Co Solenoid operated valve
US3506085A (en) * 1967-08-28 1970-04-14 Mobil Oil Corp Pneumatic acoustic source employing electromagnetic controlled valve
US3982554A (en) * 1974-04-25 1976-09-28 Tekyo Keiki Company Limited Electromagnetic flapper valve
US4238110A (en) * 1979-07-23 1980-12-09 Colt Industries Operating Corp. Electromagnetic fuel metering valve assembly
EP0024909A1 (de) * 1979-08-23 1981-03-11 Ledex, Inc. Solenoide
US4647008A (en) * 1984-08-21 1987-03-03 Toyota Jidosha Kabushiki Kaisha Solenoid valve for hydraulic control
US4946103A (en) * 1987-12-02 1990-08-07 Ganser-Hydromag Electronically controlled fuel injector
US5064166A (en) * 1990-09-20 1991-11-12 Ford Motor Company Solenoid valve with high flow capacity and low energy consumption
US20060027269A1 (en) * 2004-08-06 2006-02-09 Neff Robert H Rapid response solenoid for electromagnetic operated valve
US20060181144A1 (en) * 2005-02-16 2006-08-17 Bendix Commercial Vehicle Systems, Llc Solenoid armature with integrated spherical soft seal
US7367636B2 (en) * 2005-02-16 2008-05-06 Bendix Commercial Vehicle Systems, Llc Solenoid armature with integrated spherical soft seal
US8550428B2 (en) * 2006-05-16 2013-10-08 Mondragon Componentes, S. Coop Rotary gas tap with an integral electromagnetic valve
US20100219361A1 (en) * 2006-05-16 2010-09-02 Mondragon Componentes, S. Coop Rotary gas tap with an integral electromagnetic valve
US8136790B2 (en) * 2008-02-08 2012-03-20 Schaeffler Technologies Gmbh & Co. Kg Electromagnetic actuator for a hydraulic directional control valve
US20090200502A1 (en) * 2008-02-08 2009-08-13 Schaeffler Kg Electromagnetic actuator for a hydraulic directional control valve
US9788472B2 (en) 2010-09-15 2017-10-17 Dawn Equipment Company Row unit for agricultural implement
US11122726B2 (en) 2010-09-15 2021-09-21 Dawn Equipment Company Agricultural systems
US12150399B2 (en) 2010-09-15 2024-11-26 Deere & Company Row unit for agricultural implement
US10506755B2 (en) 2010-09-15 2019-12-17 Dawn Equipment Company Agricultural systems
US11470754B2 (en) 2010-09-15 2022-10-18 Dawn Equipment Company Agricultural systems
US10477752B2 (en) 2010-09-15 2019-11-19 Dawn Equipment Company Row unit for agricultural implement
US12171152B2 (en) 2010-09-15 2024-12-24 Deere & Company System and method for adaptively controlling depth of ground-engaging planting row unit using forward sensor that measures residue ahead of row unit
US10238024B2 (en) 2010-09-15 2019-03-26 Dawn Equipment Company Row unit for agricultural implement
US10806064B2 (en) 2011-07-01 2020-10-20 Charles H. Martin Agricultural field preparation device
US11375653B2 (en) 2011-07-01 2022-07-05 Charles H. Martin Agricultural field preparation device
US10251324B2 (en) 2011-07-01 2019-04-09 Charles H. Martin Agricultural field preparation device
US12058944B2 (en) 2011-07-01 2024-08-13 Charles H. Martin Agricultural field preparation device
US9861022B2 (en) 2013-02-01 2018-01-09 Dawn Equipment Company Agricultural apparatus with hybrid single-disk, double-disk coulter arrangement
US12389816B2 (en) 2013-02-04 2025-08-19 Deere & Company Agricultural systems
US10721855B2 (en) 2014-02-05 2020-07-28 Dawn Equipment Company Agricultural system for field preparation
US9668398B2 (en) 2014-02-05 2017-06-06 Dawn Equipment Company Agricultural system for field preparation
US10433472B2 (en) 2014-02-05 2019-10-08 Dawn Equipment Company Agricultural system for field preparation
US10485153B2 (en) 2014-02-21 2019-11-26 Dawn Equipment Company Modular autonomous farm vehicle
US9615497B2 (en) 2014-02-21 2017-04-11 Dawn Equipment Company Modular autonomous farm vehicle
US10444774B2 (en) 2014-11-07 2019-10-15 Dawn Equipment Company Agricultural system
WO2016073966A1 (en) * 2014-11-07 2016-05-12 Dawn Equipment Company Agricultural system
US10582653B2 (en) 2014-11-07 2020-03-10 Dawn Equipment Company Agricultural planting system with automatic depth control
US10251333B2 (en) 2014-11-07 2019-04-09 Dawn Equipment Company Agricultural system
US9848522B2 (en) 2014-11-07 2017-12-26 Dawn Equipment Company Agricultural system
US9723778B2 (en) 2014-11-07 2017-08-08 Dawn Equipment Company Agricultural system
US11197411B2 (en) 2014-11-07 2021-12-14 Dawn Equipment Company Agricultural planting system with automatic depth control
US20160356393A1 (en) * 2015-06-05 2016-12-08 Xiamen Koge Micro Tech Co., Ltd. Solenoid valve and solenoid valve device
US10100945B2 (en) * 2015-06-05 2018-10-16 Xiamen Koge Micro Tech Co., Ltd. Solenoid valve and solenoid valve device
US11083134B2 (en) 2015-12-28 2021-08-10 Underground Agriculture, LLC Agricultural inter-row mowing device
US10477760B2 (en) 2015-12-28 2019-11-19 Underground Agriculture, LLC Agricultural organic device for weed control
US10980174B2 (en) 2015-12-28 2021-04-20 Underground Agriculture, LLC Agricultural mowing device
US11006563B2 (en) 2017-05-04 2021-05-18 Dawn Equipment Company Seed firming device for improving seed to soil contact in a planter furrow with feature designed to prevent the buildup of soil on the outer surfaces by discharging pressurized fluid
US12089518B2 (en) 2017-05-04 2024-09-17 Dawn Equipment Company, Inc. Seed firming device for improving seed to soil contact in a planter furrow with feature designed to prevent the buildup of soil on the outer surfaces by discharging pressurized fluid
US10645865B2 (en) 2017-05-04 2020-05-12 Dawn Equipment Company Agricultural row unit with automatic control system for furrow closing device
US12290020B2 (en) 2017-05-04 2025-05-06 Deere & Company System for automatically setting the set point of a planter automatic down pressure control system with a seed furrow sidewall compaction measurement device
US10548260B2 (en) 2017-05-04 2020-02-04 Dawn Equipment Company System for automatically setting the set point of a planter automatic down pressure control system with a seed furrow sidewall compaction measurement device

Also Published As

Publication number Publication date
NL6412414A (de) 1965-05-10
CH418073A (de) 1966-07-31
DE1464526A1 (de) 1969-04-24

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