永磁有刷直流電機

基本原理

有刷(shua)電(dian)(dian)機(ji)的定子上安(an)裝有固定的主磁極和(he)電(dian)(dian)刷(shua)，轉(zhuan)(zhuan)子上安(an)裝有電(dian)(dian)樞(shu)繞(rao)組(zu)和(he)換(huan)向(xiang)(xiang)器(qi)。直(zhi)流電(dian)(dian)源的電(dian)(dian)能(neng)通過電(dian)(dian)刷(shua)和(he)換(huan)向(xiang)(xiang)器(qi)進入電(dian)(dian)樞(shu)繞(rao)組(zu)，產生(sheng)電(dian)(dian)樞(shu)電(dian)(dian)流，電(dian)(dian)樞(shu)電(dian)(dian)流產生(sheng)的磁場與主磁場相互作用產生(sheng)電(dian)(dian)磁轉(zhuan)(zhuan)矩，使(shi)電(dian)(dian)機(ji)旋(xuan)轉(zhuan)(zhuan)帶(dai)動負載(zai)。由于電(dian)(dian)刷(shua)和(he)換(huan)向(xiang)(xiang)器(qi)的存在，有刷(shua)電(dian)(dian)機(ji)的結構復(fu)雜，可靠性差，故障多，維護工作量大，壽命短(duan)，換(huan)向(xiang)(xiang)火花(hua)易產生(sheng)電(dian)(dian)磁干擾。

有(you)刷(shua)直流電機的工作原理(li)圖如(ru)圖2-1所示。在有(you)刷(shua)直流電機的固定(ding)部(bu)(bu)(bu)分(fen)有(you)磁鐵，這里稱(cheng)作主磁極;固定(ding)部(bu)(bu)(bu)分(fen)還有(you)電刷(shua)。轉動部(bu)(bu)(bu)分(fen)有(you)環形(xing)鐵芯和繞(rao)在環形(xing)鐵芯上的繞(rao)組。

圖2-1所(suo)示的(de)(de)(de)兩(liang)極有刷(shua)直流(liu)(liu)電(dian)機(ji)的(de)(de)(de)固(gu)定(ding)(ding)部分(定(ding)(ding)子(zi))上裝設(she)了(le)一(yi)對直流(liu)(liu)勵(li)磁(ci)的(de)(de)(de)靜止的(de)(de)(de)主(zhu)磁(ci)極N和(he)S，在旋(xuan)轉(zhuan)(zhuan)部分(轉(zhuan)(zhuan)子(zi))上裝設(she)電(dian)樞鐵芯。定(ding)(ding)子(zi)與轉(zhuan)(zhuan)子(zi)之間(jian)有一(yi)氣隙。在電(dian)樞鐵芯上放置了(le)由A和(he)X兩(liang)根導體連成(cheng)的(de)(de)(de)電(dian)樞線(xian)圈，線(xian)圈的(de)(de)(de)首端和(he)末端分別連到兩(liang)個圓(yuan)弧(hu)形的(de)(de)(de)銅(tong)片(pian)上，此銅(tong)片(pian)稱為換(huan)(huan)(huan)(huan)向(xiang)片(pian)。換(huan)(huan)(huan)(huan)向(xiang)片(pian)之間(jian)互相(xiang)絕緣，由換(huan)(huan)(huan)(huan)向(xiang)片(pian)構成(cheng)的(de)(de)(de)整(zheng)體稱為換(huan)(huan)(huan)(huan)向(xiang)器(qi)。換(huan)(huan)(huan)(huan)向(xiang)器(qi)固(gu)定(ding)(ding)在轉(zhuan)(zhuan)軸(zhou)上，換(huan)(huan)(huan)(huan)向(xiang)片(pian)與轉(zhuan)(zhuan)軸(zhou)之間(jian)亦互相(xiang)絕緣。在換(huan)(huan)(huan)(huan)向(xiang)片(pian)上放置著一(yi)對固(gu)定(ding)(ding)不動的(de)(de)(de)電(dian)刷(shua)B1和(he)B2，當(dang)電(dian)樞旋(xuan)轉(zhuan)(zhuan)時，電(dian)樞線(xian)圈通(tong)過換(huan)(huan)(huan)(huan)向(xiang)片(pian)和(he)電(dian)刷(shua)與外電(dian)路接(jie)通(tong)。

永磁有刷直流電機

種類

①有刷(shua)盤式(shi)(shi)繞組電(dian)(dian)(dian)(dian)機(ji)。有刷(shua)盤式(shi)(shi)繞組電(dian)(dian)(dian)(dian)機(ji)以稀(xi)土(tu)材料粘結在一缸體(ti)上，漆包銅(tong)線繞成的(de)盤式(shi)(shi)繞組置于缸體(ti)之內，構成轉子。電(dian)(dian)(dian)(dian)機(ji)相(xiang)位(wei)靠機(ji)械式(shi)(shi)換(huan)相(xiang)器(qi)(qi)調(diao)整。機(ji)械式(shi)(shi)換(huan)相(xiang)器(qi)(qi)是(shi)(shi)靠固定(ding)的(de)炭制電(dian)(dian)(dian)(dian)刷(shua)與轉動的(de)銅(tong)制換(huan)相(xiang)面摩(mo)擦來調(diao)整電(dian)(dian)(dian)(dian)壓(ya)相(xiang)位(wei)的(de)。這種電(dian)(dian)(dian)(dian)機(ji)在使用(yong)中電(dian)(dian)(dian)(dian)刷(shua)一直在磨損(sun)，電(dian)(dian)(dian)(dian)機(ji)的(de)壽(shou)命很難超(chao)過2000h。同時，由于電(dian)(dian)(dian)(dian)機(ji)的(de)轉速(su)較(jiao)高(gao)，必須采取兩(liang)級齒輪減速(su)，這就(jiu)帶(dai)來了(le)兩(liang)個問題，一是(shi)(shi)噪聲較(jiao)大，二(er)是(shi)(shi)效(xiao)(xiao)率損(sun)失大，經減速(su)后的(de)電(dian)(dian)(dian)(dian)機(ji)額定(ding)效(xiao)(xiao)率往往只能(neng)達到(dao)68%～72%。而電(dian)(dian)(dian)(dian)動自行(xing)車(che)所(suo)用(yong)的(de)蓄電(dian)(dian)(dian)(dian)池(chi)的(de)容(rong)量(liang)是(shi)(shi)有限的(de)，一般就(jiu)是(shi)(shi)36V/12Ah的(de)容(rong)量(liang)，如(ru)電(dian)(dian)(dian)(dian)機(ji)效(xiao)(xiao)率不高(gao)，將使電(dian)(dian)(dian)(dian)耗(hao)增(zeng)加，影響(xiang)續行(xing)里程。

②有(you)(you)刷印(yin)制繞組(zu)電機(ji)。有(you)(you)刷印(yin)制繞組(zu)電機(ji)以印(yin)制銅箔板作為(wei)繞組(zu)，電機(ji)重量減輕了。由于這(zhe)種電機(ji)全部是在(zai)自動生產線上生產的，工藝有(you)(you)可靠(kao)保證，從(cong)而使(shi)電機(ji)的壽命提高(gao)到3000h，噪聲(sheng)大幅度下(xia)降，效率提高(gao)到72%～76%。但這(zhe)種電機(ji)有(you)(you)“嗡(weng)嗡(weng)"的高(gao)頻(pin)噪聲(sheng)，靠(kao)齒輪減速后效率仍不理(li)想(xiang)，有(you)(you)刷換相器的使(shi)用使(shi)電機(ji)壽命無(wu)法再提高(gao)。

③有刷壓制繞(rao)組(zu)電機(ji)(ji)。這種(zhong)電機(ji)(ji)通過將(jiang)繞(rao)制好(hao)的(de)銅線壓制成一種(zhong)新型(xing)繞(rao)組(zu)，其(qi)效率可提(ti)高到74%～78%。這種(zhong)電機(ji)(ji)仍然(ran)被較多電動自行車廠家采用(yong)，但其(qi)存(cun)在的(de)效率、噪聲、壽命(ming)缺陷仍然(ran)是必須(xu)改進的(de)問題。

輪轂式有(you)(you)(you)(you)齒(chi)輪傳(chuan)(chuan)(chuan)動的(de)(de)有(you)(you)(you)(you)刷直(zhi)流電(dian)機(ji)，由(you)盤形(xing)電(dian)樞(shu)有(you)(you)(you)(you)刷電(dian)機(ji)和齒(chi)輪減(jian)速兼傳(chuan)(chuan)(chuan)動系(xi)統兩部(bu)分構成。盤形(xing)電(dian)樞(shu)是(shi)高速轉(zhuan)動的(de)(de)轉(zhuan)子(zi)。輪毅式有(you)(you)(you)(you)齒(chi)輪傳(chuan)(chuan)(chuan)動的(de)(de)有(you)(you)(you)(you)刷直(zhi)流電(dian)機(ji)的(de)(de)構造如圖2-2所示。電(dian)機(ji)的(de)(de)轉(zhuan)矩通(tong)過軸傳(chuan)(chuan)(chuan)遞(di)給第一級齒(chi)輪，經齒(chi)輪減(jian)速帶動輪轂外殼轉(zhuan)動。

有(you)刷(shua)有(you)齒(chi)(chi)輪轂電機(ji)的(de)盤形電樞(shu)是(shi)薄片(pian)形，體積(ji)很小，重(zhong)量特輕，安(an)裝(zhuang)方便。繞組(zu)編制(zhi)好之(zhi)后(hou)，用樹脂加玻(bo)璃纖維放進模內熱壓成型，在運(yun)行(xing)中由于電刷(shua)和換向器摩擦，又有(you)齒(chi)(chi)輪嚙合減速，所以有(you)刷(shua)電機(ji)的(de)運(yun)行(xing)聲音比(bi)無(wu)刷(shua)電機(ji)聲音要大(da)。

為(wei)(wei)了適(shi)應輪轂(gu)結(jie)構，將有(you)刷電(dian)機設計(ji)成電(dian)樞放在(zai)外邊(bian)作為(wei)(wei)轉(zhuan)(zhuan)子(zi)(zi)(zi)(zi)，磁(ci)鋼(gang)(gang)放在(zai)電(dian)機之內(nei)作為(wei)(wei)定子(zi)(zi)(zi)(zi)，多(duo)塊磁(ci)鋼(gang)(gang)配多(duo)個繞組，設計(ji)轉(zhuan)(zhuan)速為(wei)(wei)180r/min左右的(de)(de)低速電(dian)機。圖2-3中(zhong)(zhong)(zhong)(a)所(suo)示(shi)為(wei)(wei)電(dian)機外轉(zhuan)(zhuan)子(zi)(zi)(zi)(zi)中(zhong)(zhong)(zhong)尚(shang)未(wei)經過壓力整形的(de)(de)電(dian)樞繞組，，在(zai)繞組以內(nei)是(shi)呈(cheng)平面(mian)環狀整齊排(pai)列的(de)(de)換向片(pian)。圖2-3中(zhong)(zhong)(zhong)(b)所(suo)示(shi)的(de)(de)是(shi)放在(zai)外轉(zhuan)(zhuan)子(zi)(zi)(zi)(zi)內(nei)的(de)(de)間隔排(pai)列著(zhu)10塊磁(ci)鋼(gang)(gang)的(de)(de)定子(zi)(zi)(zi)(zi)，在(zai)中(zhong)(zhong)(zhong)間的(de)(de)轂(gu)板(ban)上(shang)開有(you)兩個孔(kong)，電(dian)刷的(de)(de)刷握就設在(zai)孔(kong)的(de)(de)背(bei)側(ce)，電(dian)刷帶著(zhu)導線被彈(dan)簧從刷握中(zhong)(zhong)(zhong)彈(dan)出。

有(you)刷電(dian)(dian)機(ji)的定子(zi)軸端套有(you)一個(ge)(ge)螺(luo)母，其作用是防止在加工中(zhong)(zhong)損(sun)傷軸上的螺(luo)紋。把(ba)電(dian)(dian)刷整理好裝(zhuang)入刷握中(zhong)(zhong)，然后將(jiang)這(zhe)一端送(song)進圖2-3中(zhong)(zhong)(a)所示的孔中(zhong)(zhong)，電(dian)(dian)刷就可(ke)以接觸(chu)換向(xiang)器平面，借助彈簧的彈力對換向(xiang)器壓(ya)緊(jin)，而磁鋼(gang)正好進入外轉(zhuan)(zhuan)子(zi)繞組(zu)中(zhong)(zhong)，只留一個(ge)(ge)很小的環形(xing)(xing)氣隙(xi)(xi)。這(zhe)個(ge)(ge)環形(xing)(xing)氣隙(xi)(xi)的直(zhi)徑越大(da)，電(dian)(dian)機(ji)產生的轉(zhuan)(zhuan)矩也越大(da)。

由于(yu)有刷電(dian)機(ji)(ji)(ji)在設計(ji)中(zhong)的(de)改進，無須齒輪(lun)減速，可實(shi)現低(di)噪(zao)聲、低(di)成本。很(hen)多低(di)價(jia)位(wei)的(de)電(dian)動(dong)自行車廣泛采用(yong)了這(zhe)種(zhong)電(dian)機(ji)(ji)(ji)。但這(zhe)種(zhong)電(dian)機(ji)(ji)(ji)扭矩小，載(zai)重負(fu)荷(he)小，爬坡能力不佳，使用(yong)時耗(hao)電(dian)較多，仍然采用(yong)機(ji)(ji)(ji)械式的(de)電(dian)刷換相器，電(dian)機(ji)(ji)(ji)壽命問(wen)題(ti)尚未(wei)得到解決(jue)，因此中(zhong)高(gao)檔電(dian)動(dong)自行車均未(wei)采用(yong)這(zhe)種(zhong)電(dian)機(ji)(ji)(ji)。