CN114207383A - 磁式编码器 - Google Patents

磁式编码器 Download PDF

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CN114207383A
CN114207383A CN202080056253.4A CN202080056253A CN114207383A CN 114207383 A CN114207383 A CN 114207383A CN 202080056253 A CN202080056253 A CN 202080056253A CN 114207383 A CN114207383 A CN 114207383A
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magnetic
permanent magnet
magnetic field
magnetic sensor
encoder
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增井隆一
石泽尚大
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SMC Corp
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    • G01MEASURING; TESTING
    • G01DMEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/244Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains
    • G01D5/245Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains using a variable number of pulses in a train
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    • G01D5/00Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • GPHYSICS
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    • G01D5/12Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/142Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage using Hall-effect devices
    • G01D5/145Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage using Hall-effect devices influenced by the relative movement between the Hall device and magnetic fields
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    • G01D5/00Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/20Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01PMEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P1/00Details of instruments
    • G01P1/02Housings
    • G01P1/026Housings for speed measuring devices, e.g. pulse generator
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01PMEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P3/00Measuring linear or angular speed; Measuring differences of linear or angular speeds
    • G01P3/42Devices characterised by the use of electric or magnetic means
    • G01P3/44Devices characterised by the use of electric or magnetic means for measuring angular speed
    • G01P3/48Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage
    • G01P3/481Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals
    • G01P3/487Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals delivered by rotating magnets
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01PMEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P3/00Measuring linear or angular speed; Measuring differences of linear or angular speeds
    • G01P3/42Devices characterised by the use of electric or magnetic means
    • G01P3/44Devices characterised by the use of electric or magnetic means for measuring angular speed
    • G01P3/48Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage
    • G01P3/481Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals
    • G01P3/488Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals delivered by variable reluctance detectors
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01DMEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D2205/00Indexing scheme relating to details of means for transferring or converting the output of a sensing member
    • G01D2205/50Grounding or electrostatically shielding a position sensor or encoder
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01DMEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/20Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
    • G01D5/2006Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the self-induction of one or more coils
    • G01D5/2013Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the self-induction of one or more coils by a movable ferromagnetic element, e.g. a core

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Abstract

磁式编码器(10)具备:第一部件(48),该第一部件包括第一壁部,该第一壁部形成有供旋转体(14)通过的插通孔(54);以及第二部件(52),该第二部件包括第二壁部(56)。在这些第一壁部(48)与第二壁部(56)之间夹有永磁铁(42)和检测由该永磁铁(42)引起的磁场变化的磁传感器(44)。在该结构中,第一部件(48)和第二部件(52)由最多含有3.0重量%的碳的软钢构成。

Description

磁式编码器
技术领域
本发明涉及一种用于检测旋转体的旋转角的磁式编码器。
背景技术
众所周知,磁式编码器具有永磁铁和磁传感器,正在广泛地用作检测旋转体的位置、旋转角的装置。如日本特开2019-15536号公报所记载的那样,永磁铁随着固定在电动机的旋转轴上的旋转体的旋转而旋转。由于该旋转,由该永磁铁产生的磁场发生变化。磁传感器检测该磁场变化。作为其结果,求出旋转轴的旋转角(或旋转量)。
在这样的结构中,当永磁铁、磁传感器受到外部磁场的影响时,检测值成为与实际的旋转角不同的值。即,旋转角的检测结果的精度降低。在日本特开2015-1511号公报中,提出了如下方案:为了避免这种情况而在覆盖磁式编码器的编码器盖的内部设置磁屏蔽部件,利用该部件阻断外部磁场。此外,在日本特开2015-1511号公报中,作为磁屏蔽部件的原材料而例示了冷轧钢板和坡莫合金。
近来,要求在来自外部的磁场产生影响的环境下进一步提高磁式编码器对旋转体的旋转角的检测精度。
发明内容
本发明的主要目的在于提供一种能够降低来自外部的磁场的影响的磁式编码器。
本发明的另一个目的在于提供一种检测精度进一步提高的磁式编码器。
根据本发明的一个实施方式,提供一种磁式编码器,该磁式编码器具有:永磁铁,该永磁铁随着构成旋转驱动部的旋转体旋转而旋转;以及磁传感器,该磁传感器检测所述永磁铁的磁场变化,其特征在于,具备:
第一部件,该第一部件包括第一壁部,该第一壁部形成有供所述旋转体通过的插通孔;以及
第二部件,该第二部件包括第二壁部,在该第二壁部与所述第一壁部之间夹着所述永磁铁和所述磁传感器,
所述第一部件及所述第二部件由最多含有3.0重量%的碳的软钢构成。
根据本发明,分别包括将永磁铁和磁传感器夹在中间的第一壁部、第二壁部的第一部件、第二部件,由最多含有3.0重量%的碳的软钢构成。由于这些第一部件和第二部件作为磁阻断部发挥功能,因此,例如在设有磁式编码器的电动机产生的磁场或在其他设备产生的外部磁场能被第一部件和第二部件阻断。
即,在这种情况下,能够抑制外部磁场的影响波及到永磁铁和磁传感器的情况。因此,由磁传感器检测出的磁场的大部分为由永磁铁产生的磁场。
这样,根据上述的结构,能够在阻断了外部磁场等的状况下利用磁传感器检测由永磁铁引起的磁场变化。因此,能够高精度地求出基于永磁铁的磁场变化的旋转体的旋转角。即,提高与旋转体的旋转角相关的检测精度。
附图说明
图1是设置有本发明的实施方式所涉及的磁式编码器的电动机(旋转驱动部)的概略整体主视图。
图2是图1中的II-II线向视剖视图。
图3是构成图1的磁式编码器的筒状部件的概略展开图。
图4是从图3使侧板部弯曲而得到的筒状部件的概略立体图。
图5是设有省略了内部壳体的磁式编码器的电动机的概略纵剖视图。
图6是设有另一实施方式所涉及的磁式编码器的电动机的概略纵剖视图。
具体实施方式
以下,关于本发明所涉及的磁式编码器而列举优选的实施方式,并参照附图进行详细说明。此外,以下的“下”及“上”与图1及图2中的下方、上方对应,但这是为了简化说明而使理解变容易的方便起见,并非是特别指定使用磁式编码器时的姿势。另外,以下,也有时将磁式编码器仅表述为“编码器”。
图1是设有本实施方式所涉及的编码器10的电动机12(旋转驱动部)的概略整体主视图,图2是图1中的II-II线向视剖视图。编码器10具有检测电动机12的旋转轴14(旋转体)的旋转角的功能。
首先,对电动机12进行概略说明。电动机12具有被底盖16和顶盖18夹着的定子20以及收容在该定子20的中空内部的转子22(参照图2)。众所周知,在定子20设有随着通电而带有磁性的未图示的电磁线圈。另一方面,在转子22设有未图示的永磁铁。此外,定子20由4个面的外壁构成大致四棱柱形状。另外,该定子20的中空内部构成以与长度方向正交的方向的截面为大致正圆的方式挖通了圆柱体这样的形状。
在底盖16和顶盖18分别形成有大径的第一收容凹部24、第二收容凹部26以及与该第一收容凹部24、该第二收容凹部26相连的第一贯通孔28、第二贯通孔30。第一贯通孔28、第二贯通孔30被设定为直径比第一收容凹部24、第二收容凹部26的直径小,而且,第二贯通孔30被设定为直径比第一贯通孔28的直径大。并且,在第一收容凹部24、第二收容凹部26分别收容有第一轴承32、第二轴承34。
在转子22设置有作为旋转体的旋转轴14。旋转轴14的下端部和上端部分别从转子22的下端面和上端面露出,并且以朝向底盖16、顶盖18的方式延伸。其中的下端部穿过第一轴承32及第一贯通孔28而从底盖16露出。此外,旋转轴14可以是实心的,也可以是中空的。
另一方面,上端部贯通第二轴承34和第二贯通孔30,其端部从顶盖18露出到外部。上端部的最顶端进入后述的内室40。
接着,对本实施方式所涉及的编码器10进行说明。该编码器10具备:保持架62,该保持架设置于旋转轴14的最顶端;检测用的永磁铁42,该永磁铁与形成于该保持架62的上端面的保持用凹部66嵌合;磁传感器44,该磁传感器保持于传感器基板70且以与该永磁铁42的一部分相对的方式配设;以及外壳46,该外壳划分出收容这些永磁铁42和磁传感器44的内室40。
外壳46通过将作为第一部件的封闭部件48和筒状部件52(第二部件)组合而构成,该封闭部件48具有呈大致正方形的壁部(第一壁部),该筒状部件52近似于较短的四方筒形状且在角部形成有狭缝50。即,在该情况下,筒状部件52的下端为开口端。该开口端被封闭部件48封闭,由此在筒状部件52的内部形成内室40。
在封闭部件48沿其厚度方向形成有插通孔54。旋转轴14的最顶端穿过该插通孔54而进入内室40。旋转轴14与形成插通孔54的壁部之间的间隙CL优选为3mm以内。这是因为,在间隙CL超过3mm的情况下,存在由电动机12产生的磁场通过间隙CL而进入内室40的担忧。换言之,在这种情况下,不容易通过封闭部件48阻断内室40的外部的磁力。
如作为筒状部件52的概略展开图的图3所示,筒状部件52具有顶板部56(第二壁部)和分别与该顶板部56相连的五个侧板部58。如图2所示,永磁铁42及磁传感器44以被夹在封闭部件48(第一壁部)与顶板部56(第二壁部)之间的方式配设。
为了得到筒状部件52,通过对后述那样的由软钢构成的板材进行冲裁加工而得到图3所示的形状的中间成形体,接着,将侧板部58以与顶板部56大致正交的方式折弯大致90°。由此,如图4所示,得到在侧板部58彼此之间形成有狭缝50的筒状部件52。
在被折弯的较短的两个侧板部58彼此之间形成有窗部60。在该窗部60中通过有用于将磁传感器44和运算部电连接的信号线。此外,运算部和信号线未图示。
在此,封闭部件48和筒状部件52由最多含有3.0重量%的碳的软钢构成。这是因为,软钢容易实施成形加工,因此,能够容易地得到筒状部件52等。作为这种软钢的优选例,可举出冷轧软钢板、热轧软钢板。作为冷轧软钢板,可例示出SPCC、SPCD、SPCE、SPCF、SPCG,作为热轧软钢板,可例示出SPHC、SPHD、SPHE、SPHF。此外,SPCC、SPCD、SPCE、SPCF、SPCG是JISG 3141中规定的材料符号,SPHC、SPHD、SPHE、SPHF是JIS G 3131中规定的材料符号。当然,JIS表示日本工业标准。
特别优选SPCC。这是因为SPCC廉价且容易获得。即,在采用SPCC的情况下,能够以低成本制作外壳46。
通常,作为构成磁阻断部的材料,选定磁导率大且容易被磁化的材料。与此相对,上述的软钢的相对磁导率均小于5000,与坡莫合金或纯铁、硅铁等磁性材料相比明显小。即,软钢吸收磁通量的能力差,难以被磁化。但是,在本实施方式中,由软钢构成的外壳46作为阻断外部的磁力而妨碍该磁力到达内室40的磁阻断部发挥功能。
筒状部件52和封闭部件48换言之外壳46的保持力优选为3Oe以下。即,外壳46是在外部的磁场被除去了时容易丧失磁性(磁力)的软磁性体。要将筒状部件52和封闭部件48的保持力设为3Oe以下,只要对SPCC这样的软钢实施磁退火即可。在由原材料(软钢板)经过成形加工等而得到的外壳46的金属组织中,金属粒粗大化、或产生粒径的不均匀化。但是,通过实施磁退火,金属粒微细化且粒径大致均等地整齐。由此,由加工等引起的残余应变被除去,并且保持力降低至3Oe以下。
筒状部件52及封闭部件48的厚度T优选设定为0.5~2mm。若不足0.5mm,则它们为薄壁而因此磁力容易通过筒状部件52、封闭部件48。即,在这种情况下,不容易阻断外部的磁力。另外,若超过2mm,则外壳46为厚壁而因此重量变大。进而,若筒状部件52及封闭部件48的厚度T为0.5~2mm,则磁力难以通过这样的厚壁的筒状部件52、封闭部件48。因此,这些筒状部件52及封闭部件48能够充分地阻断外壳46外的磁场。
在进入内室40的旋转轴14的上端部的最顶端设置有呈大致圆板形状的保持架62。具体而言,在保持架62的下端面突出形成有圆环状凸部64,并且在该圆环状凸部64的圆形状的中空内部嵌合有旋转轴14的上端部。另一方面,在保持架62的上端面形成有有底的保持用凹部66。检测用的永磁铁42通过嵌合于该保持用凹部66而被保持于保持架62。
在内室40收容有传感器基板70,并且在该传感器基板70设置有所述磁传感器44。如上所述,磁传感器44与永磁铁42的一部分相对。磁传感器44经由所述信号线与所述运算部电连接,经由该信号线向所述运算部发送检测信号。
在内室40收容有呈方筒形状且由树脂构成的内部壳体72。保持架62、永磁铁42、传感器基板70以及磁传感器44收容于内部壳体72的中空内部。换言之,保持架62、永磁铁42、传感器基板70以及磁传感器44被内部壳体72围绕。在内部壳体72形成有与窗部60相连的未图示的连通孔,将磁传感器44与运算部连接的所述信号线从连通孔以及窗部60引出到内室40的外部。
对编码器10的制造过程进行若干说明。在制作筒状部件52时,如上所述,使用由软钢(例如SPCC)构成的板材进行冲裁加工,得到图3所示的形状的中间成形体。接着,使侧板部58以与顶板部56大致正交的方式折弯大致90°而做成筒状部件52。在原材料为SPCC的情况下,特别容易进行冲裁加工、折弯。封闭部件48也同样地通过使用由软钢构成的板材作为原材料的冲裁加工而得到。
进一步,对这些筒状部件52及封闭部件48实施磁退火。磁退火的处理条件优选设定为筒状部件52及封闭部件48的保持力为3Oe以下。此外,在作为代表性的碳钢的S45C中,保持力比较大,约为41Oe左右。另外,即使对碳量为0.5重量%的低碳钢实施退火,保持力也约为8Oe。由此可知,外壳46的保持力比一般的碳钢的保持力小。
接着,将内部壳体72收容于实施了磁退火的筒状部件52内,进一步,将传感器基板70及磁传感器44收容于该内部壳体72的中空内部。另一方面,在顶盖18的上端面配设封闭部件48,使旋转轴14的上端部的最顶端通过了插通孔54之后,将保持有永磁铁42的保持架62安装在该最顶端。当然,此时,将旋转轴14的上端部嵌合在设于保持架62的下端面的圆环状凸部64的中空内部。
接着,将筒状部件52覆盖于封闭部件48,经由螺纹件等未图示的连结部件将筒状部件52与封闭部件48接合。由此,构成编码器10。
本实施方式所涉及的编码器10基本上如以上那样构成,接着,对其作用效果进行说明。
编码器10检测旋转轴14的旋转角。即,当对构成定子20的电磁线圈进行通电时,随之在定子20产生交变磁场。在该交变磁场与由转子22中的永磁铁产生的磁场之间发生排斥和吸引,由此转子22与旋转轴14一体地旋转。此外,在旋转轴14与底盖16、顶盖18之间夹装有第一轴承32、第二轴承34,因此底盖16、顶盖18、定子20不会跟随旋转。
随着旋转轴14的旋转,设置于其上端部的最顶端的保持架62旋转,同时,保持于该保持架62的检测用的永磁铁42旋转。该永磁铁42以沿着环绕方向交替出现多个N极和S极的方式配置。因此,当永磁铁42旋转时,N极和S极交替地与磁传感器44相对。因此,在磁传感器44的附近,由永磁铁42产生的磁场发生变化。伴随该磁场变化,从磁传感器44经由所述信号线向所述运算部发送的检测信号发生变化。
运算部基于检测信号的变化来识别磁场发生了变化的情况,根据变化的次数和程度,通过运算求出旋转轴14的旋转角。由此,检测旋转轴14的旋转角。
在此,在电动机12中,如上述那样由电磁线圈以及永磁铁产生磁场。然而,该磁场被封闭部件48遮挡。即,通过封闭部件48,有效地防止了电动机12产生的磁场对内室40内的永磁铁42和磁传感器44造成影响的情况。
另外,虽然可设想在产生外部磁场的设备(其他电动机、电磁线圈等)配置于外壳46的附近的状况下使用编码器10,但是,在该情况下,筒状部件52遮挡外部磁场。换言之,通过筒状部件52,有效地防止了在外壳46外产生的外部磁场对内室40内的永磁铁42和磁传感器44造成影响的情况。
另外,通过将筒状部件52及封闭部件48的厚度T设定为0.5~2mm,也能够对内室40有效地阻断在电动机12产生的磁场或外部磁场。而且,若将形成插通孔54的壁部与旋转轴14之间的间隙CL设定为3mm以下,则能够防止电动机12产生的磁场经由插通孔54进入内室40的情况。
以上的设置互起作用,能够充分地抑制永磁铁42、磁传感器44受到在电动机12产生的磁场或外部磁场的影响的情况。因此,磁传感器44的检测信号的大部分基于由检测用的永磁铁42产生的磁场。运算部基于检测信号来检测旋转轴14的旋转角,因此能够高精度地求出旋转轴14的旋转角。即,旋转角的检测精度变良好。
典型地,若在使用未实施磁退火的外壳而构成的编码器中求出的角度误差与在使用实施磁退火而保持力为3Oe以下的外壳46构成的编码器10中求出的角度误差进行对比,则后者为前者的大致1/2。由此明显可知,外壳46作为磁阻断部有效地发挥功能。此外,角度误差被算出为从检测旋转角减去实际旋转角后的值。
这样,根据将永磁铁42以及磁传感器44收容于实施了磁退火的外壳46的内室40的本实施方式,该外壳46作为磁阻断部发挥功能,因此能够提高与旋转轴14的旋转角相关的检测精度。
另外,由于在内室40内配置内部壳体72,因此通过该内部壳体72保护永磁铁42及磁传感器44不受尘埃等异物的影响。因此,能够避免异物咬入第二轴承34的情况等。
在旋转角的检测结束后,停止向电磁线圈的通电。其结果,转子22及旋转轴14的旋转停止。伴随于此,电动机12产生的磁场消失。在封闭部件48的保持力小于3Oe以下的情况下,当由构成电动机12的定子20产生的磁场消失时,封闭部件48迅速地丧失与该磁场相应的磁性。因此,难以在封闭部件48残留大的磁性。因此,能够尽可能地抑制如下情况:在下次的旋转角的检测时,残留于封闭部件48的磁性的影响波及到永磁铁42、磁传感器44。
筒状部件52也同样地在保持力为3Oe以下这样小的情况下,在外部磁场消失了时迅速地丧失磁性。即,在该情况下,难以在筒状部件52残留磁性。因此,能够避免如下情况:在下次的旋转角的检测时,永磁铁42、磁传感器44受到残留于筒状部件52的磁性的影响。
如上所述,通过减小外壳46的保持力,能够在下次的旋转角的检测时高精度地求出旋转角。
本发明并不特别限定于上述的实施方式,能够在不脱离本发明的主旨的范围内进行各种变更。
例如,也可以通过拉深成形来制作筒状部件52。在该情况下,也能够将筒状部件52作为未形成有狭缝50的部件而得到。
并且,也可以将筒状部件52设为第一部件且将封闭部件48设为第二部件。在该情况下,只要使筒状部件52的开口端朝向图1及图2的上方即可。
另外,并非必须设置树脂制的内部壳体72,如图5所示,也可以省略内部壳体72而构成编码器90。
而且,在该实施方式中,虽然例示了使用筒状部件52作为第二部件的情况,但是,如图6所示,作为第二部件,也可以使用仅具有平板形状的第二壁部的平板部件100来构成编码器102。在该情况下,通过由树脂构成且四方筒形状的壳体104和封闭该壳体104的开口端的封闭部件48来形成内室106、并将永磁铁42和磁传感器44收容于该内室106内即可。
在该情况下,封闭部件48和平板部件100作为磁阻断部发挥功能。即,在该实施方式中,也能够得到与图1~图5所示的编码器10、90相同的效果。
不论在哪一个实施方式中,都可以经由齿轮、带轮等旋转部件间接地或直接地将另外的旋转体(旋转部件)连结于旋转轴14的下端部。在该情况下,通过检测电动机12的旋转轴14的旋转角,能够间接地求出旋转体的旋转角。
符号说明
10、90、102…磁式编码器 12…电动机
14…旋转轴 20…定子
22…转子 40、106…内室
42…永磁铁 44…磁传感器
46…外壳 48…封闭部件
50…狭缝 52…筒状部件
54…插通孔 62…保持架
70…传感器基板 72…内部壳体
100…平板部件 104…壳体
CL…间隙

Claims (7)

1.一种磁式编码器,具有:永磁铁(42),该永磁铁随着构成旋转驱动部(12)的旋转体(14)旋转而旋转;以及磁传感器(44),该磁传感器检测所述永磁铁的磁场变化,其特征在于,具备:
第一部件(48),该第一部件包括第一壁部,该第一壁部形成有供所述旋转体通过的插通孔(54);以及
第二部件(52),该第二部件包括第二壁部(56),在该第二壁部与所述第一壁部之间夹着所述永磁铁和所述磁传感器,
所述第一部件和所述第二部件由最多含有3.0重量%的碳的软钢构成。
2.根据权利要求1所述的磁式编码器,其特征在于,
所述第一部件和所述第二部件由冷轧软钢板构成。
3.根据权利要求1或2所述的磁式编码器,其特征在于,
所述第一部件和所述第二部件的保持力为3Oe以下。
4.根据权利要求1至3中任一项所述的磁式编码器,其特征在于,
所述第一部件和所述第二部件的厚度为0.5~2mm。
5.根据权利要求1至4中任一项所述的磁式编码器,其特征在于,
所述旋转体与形成所述插通孔的所述第一壁部之间的间隙为3mm以内。
6.根据权利要求1至5中任一项所述的磁式编码器,其特征在于,
在所述第一部件与所述第二部件之间设置有收容所述永磁铁和所述磁传感器的壳体(72)。
7.根据权利要求1至6中任一项所述的磁式编码器,其特征在于,
所述第一部件和所述第二部件中的一方由一端为开口端的筒状部件构成,且剩余的一方为封闭所述开口端的封闭部件。
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TW202113309A (zh) 2021-04-01
US20220299306A1 (en) 2022-09-22
JP7533464B2 (ja) 2024-08-14
EP4012354A1 (en) 2022-06-15
JPWO2021029305A1 (zh) 2021-02-18
MX2022001636A (es) 2022-03-11
BR112022002403A2 (pt) 2022-04-26

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