US3831925A - Spiral spring units for pressing brushes - Google Patents

Spiral spring units for pressing brushes Download PDF

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Publication number
US3831925A
US3831925A US00294804A US29480472A US3831925A US 3831925 A US3831925 A US 3831925A US 00294804 A US00294804 A US 00294804A US 29480472 A US29480472 A US 29480472A US 3831925 A US3831925 A US 3831925A
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United States
Prior art keywords
spiral spring
spring
spiral
brush
springs
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Expired - Lifetime
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US00294804A
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English (en)
Inventor
T Nakamura
S Kawai
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Hitachi Ltd
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Hitachi Ltd
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Publication date
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    • 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
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F1/00—Springs
    • F16F1/02—Springs made of steel or other material having low internal friction; Wound, torsion, leaf, cup, ring or the like springs, the material of the spring not being relevant
    • F16F1/04—Wound springs
    • F16F1/10—Spiral springs with turns lying substantially in plane surfaces

Definitions

  • ABSTRACT A spiral spring unit for pressing brushes, which consists of a plurality of spiral spring elements bonded together at the opposite ends thereof and which is capable of pressing the brush always with a constant pressure.
  • the brush pressing spiral spring unit of the present invention can be used at the current collecting portions of any and all rotary electric machines, but herein it will be described as used at the current collecting portion of an electric motor for vehicles, to facilitate best understanding of the invention.
  • a brush and a brush holder At the current collecting portion of a vehicle motor or the like are generally provided conductor wires, a brush and a brush holder, by which current is conducted between a stationary portion and a rotating portion.
  • this type of motor is usually arranged at a place, such as below the floor of a vehicle, where the space is not substantially large, the motor is required to be small in size per. se. and accordingly not a large space is available around the current collecting portion of the motor.
  • the brush and the brush holder are also required to be small in size as a matterof course.
  • the most ideal collector of this type is the one which is small in size and free of maintenance, or in other words, the one which is operable for an extended period of time without the necessity for changing the brush used therein.
  • a brush holder including a spiral spring is presently being employed as the most desirable brush holding means, which satisfies substantially all of the requirements set forth above.
  • the brush holder having a spiral spring has many advantages, such as that since the spring does not have a rotating or sliding portion, there is no fear of the relative rotation or sliding of the brush holder being impaired by the brush powder or dusts in air attaching to the contacting portion; that it is relatively small in size and can be used with a brush having a large height; and that it can absorb the vibrations of the brush because the spring is small in inertia per. se.
  • the brush holder having a spiral spring has been widely used as the most effective one, at least to the present time.
  • FIG. 5 there is shown a spiral spring 10 having a relatively large number of turns.
  • the spring is subjected to a displacement as indicated by the chain line when set in a brush pressing position.
  • Each turn of the coiled portion of the spring is also subjected to a slight displacement in this case but such displacement is not shown.
  • the brush portion of a rotary electric machine rises in temperature during operation of said machine. Therefore, an increase of stress in a brush holding spring tends to result in a lowering of the spring pressure due to the creeping phenomenon and the intertum interference of the coiled portion of the spring causes an abnormal vibration of the spring, all of which provide causes of unsatisfactory commutation.
  • a motor for vehicles is normally used in a wide range of speed from zero to 500 r.p.m. but a spiral spring consisting of a single spring plate has its resonance point in the neighbourhood of 1,000 6,000 C.P.m., so that such a spring during operation tends to become defective in both the pressure characteristic and vibration characteristic, due to occurrence of resonance of the turns of the spring.
  • the present invention has been achieved under the circumstances described above. It is, therefore, the object of the invention to provide a spring unit of the type described, which is small in size, capable of pressing a brush with a minimum pressure change and with a minimum stress, and has a large resonance suppressing and damping effect.
  • a spring unit of a small size, a low stress and a small pressure change which is composed of a first spiral spring having one end secured to a stationary body for pressing a brush at the other end thereof and a second spiral spring coiled into a configuration substantially concentric with and disposed within the spiral space of said first spiral spring, one end of said second spiral spring being secured to the same stationary body to which the first spiral spring is secured, and the other end thereof being bonded to the other end portion of said first spiral spring.
  • a spring unit of the character described in which said first and second spiral springs have different spring constants thereby to enhance the resonance suppressing and damping effect of the spring unit, and further said second spiral spring is smaller in width than said first spiral spring and arranged in close contact with the side of said first spiral spring closer to the axis thereof thereby to facilitate the fabrication of the spring unit.
  • FIG. 1 is a perspective view of a brush holder comprising the spring unit of the present invention
  • FIG. 2 is a side elevational view of the spring unit only of the brush holder shown in FIG. 1;
  • FIGS. 3 and 4 are side elevational views respectively showing other embodiments of the spring unit of the invention.
  • FIG. 5 is a side elevational view of a conventional spring unit.
  • FIG. 1 there is shown in perspective a brush holder 3 comprising a brush 1 and a spring unit 2.
  • the brush holder 3 has at one end thereof a brush receiving box 4 in which the brush 1 is slidably received.
  • the brush holder 3 also has a fixed pin 5 which has the inner end 6 of the spring unit 2 secured thereto and thus supports the entire spring unit 2.
  • the outer end 7 of the spring unit 2 is placed on the top of the brush 1, and the brush is normally urged into pressure contact with a collector ring (not shown) as indicated by the arrow, under the biasing force of the spring unit.
  • the brush holder 3 comprising the spring unit 2 and the brush 1 is fixed to a predetermined stationary portion (not shown) through an insulation rod
  • the spring unit 2 as shown in FIG. 2, is composed of a first spiral spring 2a secured to the fixed pin 5 of the brush holder at one or inner end and having a brush pressing portion at the other or outer end thereof, and a second spiral spring 2b disposed within the spiral space of said first spiral spring.
  • the second spiral spring 2b similar to the first spiral spring 2a, is secured to the fixed pin 5 at the inner end thereof, and the outer end thereof is bonded integrally with the outer end of the first spiral spring 2a.
  • the spring unit 2 may be fabricated in the form shown in FIG. 3.
  • the thickness t of a first spiral spring 2c is differentiated from the thickness T of a second spiral spring 2d.
  • Differentiating the thicknesses means to differentiate the natural vibrations of the springs and has the effect of suppressing the vibration of the spring unit as a whole, though will be described in greater detail later, and thus makes it possible to use the spring unit with machines and equipments which are subjected to intense vibrations. Besides differentiating the thicknesses, many other methods may of course be considered to differentiate the natural vibrations of both springs, such as differentiating the materials or widths of the springs.
  • FIG. 4 is shown a spring unit in which the first and second spiral springs of different thicknesses mentioned above are bonded together over substantially the entire lengths thereof and especially the second spiral spring 2d having a relatively small thickness is bonded to that side of the first spiral spring 2c having a relatively large thickness which is closer to the axis of the springs.
  • This spring unit will not be described here as they will be described in detail later.
  • a stress 0' occurring in a spiral spring is in inverse proportion to the square of the plate thickness and the angle of torsion 0: thereof is in inverse proportion to the cube of the plate thickness, for the same output. Therefore, by forming the spiral spring unit by laminating the first and second spiral springs of smaller thicknesses (than the conventional one) as described herein, it becomes possible, for the same output, to reduce the effective length of the spring unit and hence to reduce the number of turns and to make the angle of torsion large, or in other words, to minimize a change in pressure of the spring occurring incident to wear of the brush and'to reduce the stress.
  • first and second springs are respectively made of materials which have different spring constants, they have different natural frequencies, so that the energy loss occurring at the time of vibration due to mutual inteference of the laminated spring plates, i.e., the vibration damping effect, becomes very large and thus a spiral spring unit can be obtained which is excellent in its effect of suppressing resonance or abnormal vibration.
  • the spring unit of the invention is composed of the first and second spiral springs bonded with each other at the opposite ends thereof and, therefore, is small in size, low in stress and small in pressure change, owing to the inherent properties of the springs. Further, the springs are made of material having different spring constants and the plate thicknesses of the springs are differentiated, and further the spring of smaller thickness is disposed inside of the spring of larger thickness with respect to the axis of the springs, so that the spring unit has a large effect for sup pressing or damping resonances and can be easily produced, in addition to the advantageous features set forth above.
  • a spiral spring unit for pressing brushes comprising: a stationary body, a first spiral spring having one end secured to said stationary body, the other end of said first spiral spring pressing a brush in a predetermined direction, a second spiral spring having a spiral configuration substantially concentric with said first spiral spring, said second spiral spring being disposed within the spiral space formed by said first spiral spring with a space being provided between said first and second spiral springs, one end of said second spiral spring being secured to the same stationary body to which said first spiral spring is secured, the other end of said second spiral spring being bonded to said other end portion of said first spiral spring, said other end portions being bonded together to cause said space between said first and second spiral springs to decrease when said first and second springs are wound up.
  • a spiral spring unit for pressing brushes as defined in claim 1, wherein said first and second spiral springs have different spring constants.
  • a spiral spring unit for pressing brushes as defined in claim 1, wherein the spring constant of said second spiral spring is smaller than that of said first spiral spring.
  • a spiral spring unit for pressing brushes as defined in claim 1, wherein said second spiral spring has a plate thickness smaller than that of said first spiral spring.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Motor Or Generator Current Collectors (AREA)
US00294804A 1971-10-06 1972-10-04 Spiral spring units for pressing brushes Expired - Lifetime US3831925A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP7792771A JPS5654674B2 (enrdf_load_stackoverflow) 1971-10-06 1971-10-06

Publications (1)

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US3831925A true US3831925A (en) 1974-08-27

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ID=13647707

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Application Number Title Priority Date Filing Date
US00294804A Expired - Lifetime US3831925A (en) 1971-10-06 1972-10-04 Spiral spring units for pressing brushes

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US (1) US3831925A (enrdf_load_stackoverflow)
JP (1) JPS5654674B2 (enrdf_load_stackoverflow)
AU (1) AU452319B2 (enrdf_load_stackoverflow)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003051160A1 (en) * 2001-12-14 2003-06-26 Braitrim (Uk) Limited Garment hanger
EP1347196A1 (de) * 2002-03-19 2003-09-24 Bernt Dr. Schroer Spiralfeder mit mehreren in einer Ebene ineinander angeordneten Federwindungen
US20070153964A1 (en) * 2006-01-04 2007-07-05 General Electric Company Method and device for stabilizing a steam dryer assembly in nuclear reactor pressure vessel
US20100258327A1 (en) * 2007-11-27 2010-10-14 Florian Esenwein Electrically driven hand-held power tool
US20140027965A1 (en) * 2012-07-27 2014-01-30 Ametek Constant-force spring systems

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS50122612A (enrdf_load_stackoverflow) * 1974-03-18 1975-09-26
WO1990002275A1 (en) * 1988-08-22 1990-03-08 William King Springs and reels
JPH0459536U (enrdf_load_stackoverflow) * 1990-09-28 1992-05-21

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3047281A (en) * 1960-09-09 1962-07-31 Ametek Inc Springs
US3047280A (en) * 1959-02-25 1962-07-31 Ametek Inc Spring motor
US3427487A (en) * 1966-08-29 1969-02-11 Cons Foods Corp Motor brush holder
US3581774A (en) * 1969-04-01 1971-06-01 Us Navy Constant pressure accumulator

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3047280A (en) * 1959-02-25 1962-07-31 Ametek Inc Spring motor
US3047281A (en) * 1960-09-09 1962-07-31 Ametek Inc Springs
US3427487A (en) * 1966-08-29 1969-02-11 Cons Foods Corp Motor brush holder
US3581774A (en) * 1969-04-01 1971-06-01 Us Navy Constant pressure accumulator

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003051160A1 (en) * 2001-12-14 2003-06-26 Braitrim (Uk) Limited Garment hanger
US20050035159A1 (en) * 2001-12-14 2005-02-17 Hunt William Joseph Garment hanger
US7270252B2 (en) * 2001-12-14 2007-09-18 Braitrim (Uk) Limited Garment hanger
EP1347196A1 (de) * 2002-03-19 2003-09-24 Bernt Dr. Schroer Spiralfeder mit mehreren in einer Ebene ineinander angeordneten Federwindungen
US20070153964A1 (en) * 2006-01-04 2007-07-05 General Electric Company Method and device for stabilizing a steam dryer assembly in nuclear reactor pressure vessel
US7596199B2 (en) * 2006-01-04 2009-09-29 General Electric Company Method and device for stabilizing a steam dryer assembly in nuclear reactor pressure vessel
US8311179B2 (en) 2006-01-04 2012-11-13 General Electric Company Methods for stabilizing a steam dryer assembly in a nuclear reactor pressure vessel
US20100258327A1 (en) * 2007-11-27 2010-10-14 Florian Esenwein Electrically driven hand-held power tool
US20140027965A1 (en) * 2012-07-27 2014-01-30 Ametek Constant-force spring systems

Also Published As

Publication number Publication date
JPS5654674B2 (enrdf_load_stackoverflow) 1981-12-26
JPS4843107A (enrdf_load_stackoverflow) 1973-06-22
AU4748172A (en) 1974-04-11
AU452319B2 (en) 1974-09-05

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