I29533^fd0c 九、發明說明： 【發明所屬之技術領域】 用之特別是關於—種為移送高壓、高黏性流體而使 【先前技術】 於藉㈣合之齒輪之旋轉而將流體自吸 t之齒輪u，通常使用漸開線(i腾lute)正齒輪（= 較1)易因ί漸開線齒形易切削，齒形的成品尺寸之測定亦 平又今易，故而可獲得高精度之齒輪。 另-方面’漸開線正齒輪伴有流體封閉現象沪。 此二==中’於旋轉中存在兩組齒相互嚙合之期；， 及動力浪»，_«會導致產生衫錢泡料良^。 亚且’封閉現象之危害於所移送之流體黏度或吸入舞 力^土出遂力較高時越為顯著。故而，用以壓送 : 般面壓、高黏度流體之泵難以採用漸開線正齒輪广曰 若採用螺旋齒輪（hdkal gea〇，且將 ’ __朗現象 輪系所體之I力變化並非急劇，^ 不滑，亦可抑㈣音或振動。 ” il 口亦較 然而，螺旋齒輪於旋轉中受到軸向推 之:二咖面被猛亀方向而=二 時亦會引起灼燒。故而’通常使用可抵消轴向推力 5 聰縱doc j Rouble hdlcal gear)(例如參照日本公開專利公報 本f利特開平⑽-014165號公報））。 相互^齒輪不易形成。#前，製作人字齒輪時多為接合 η之兩個螺旋齿輪而成為一個人字齒輪。但是，若 二要：：：則齒輪與齒輪軸必須為不同構件。於是，不 二、以將齒輪與齒輪軸結合之鍵以及鍵槽等進行形 大』^而且齒輪或#輪軸亦會沿直徑方向增大而導縣 【發明内容】 欲實發而成之本發明不使用人字齒輪，而 向壓、高黏度流體之齒輪泵。 體心入側’二：屮於藉由所嚙合之螺旋齒輪之旋轉而將流 設置自吐出側向齒 二=== ，設==低= 的不良影響。因為可保證 用螺格條件。總之1 若進而設置用以調整上；^丄:：度流體之齒輪泵。 體壓力的續敫μ，θϊ 上这ν入路中所流通之流體之流 推力所需要:;分丄周整閥之調整來抵消轴向 ，體之泵特別有效。於屢送非牛 表觀黏度亦產生變^ ^ ^切速率產生變化則 又化’故而設計階段所假定之軸向推力與 6 1295氣 實際產生之軸向推力常不-致。故而，難以預先決定經由 ，導入路而導入之流體壓力，最好的是可於流體實 轉時對其進行調整。 、、 又’由於同樣之原因’較好的是設置計測上述導 中所流通之流體之流體壓力的壓力計。 若將各齒輪與對應該齒輪之齒輪轴設為一體成型口， 則有助於泵之小型化。採用人字齒輪時，若欲盥= 轴一體形成，則於齒輪加工步驟中，齒輪規格會產 設定為最佳值。於本發明中，採㈣旋齒輪而不採 角設定為最佳值。輪軸體形成’且容許將扭轉 側口：ί置Ϊ經由上述導入路而導入軸端側之流體向吸入 流Τ並且於承受齒輪軸之轴承内周形成用以 級入體進行潤滑之凹槽；而且使該凹槽愈上述回 ^導入路連通，則可同時實現軸向推权平衡妹承i 旋齒:而齒轴之軸心方向貫臟 而使内面於後閉止上述本體 以及蓋各自之内面形成上述導入路 可將調整帽力計衷設;化。又， 步驟之簡便化。 』皿後皿，亦有助於泵裝配 根據本兔明，無需使用人字齒輪即可實現適於移送高 7 12953淑-.. 壓、高黏度流體之齒輪泵。 【實施方式】 以下’參照圖式就本發明之一實施形態加以說明。圖 1至圖3所示之本實施形態之齒輪泵於例如石油工廠、化 學工廠等中用以高壓壓送熔融樹脂以及其他高分子聚合物 等。該齒輪泵是於外殼1内包之内部空間中以嚙合狀態配 ，驅動齒輪2與從動齒輪3而成之所謂外接齒輪泵，發揮 藉由旋轉驅動兩齒輪2、3而將滯留於齒槽之流體自吸入側 移送至吐出側之泵作用者。實際上使吸入側位於上方，使 ，出侧位於下方，於吸入口 1U之正上方設置儲存有熔融 树月曰等之儲藏罐(tank)，吸入儲藏罐中之熔融樹脂等，並自 吐出口 112以所需之吐出壓力吐出。 外殼1以本體11、前蓋12以及後蓋13作為構件。於 本體11中穿没有沿前後方向貫通之眼鏡孔，於該眼鏡 孔113内收納齒輪2、3、齒輪轴21、31以及軸承4。具體 的是，將軸承4設置於眼鏡孔113之前後端部，可旋轉地 支撐齒輪軸21、31 ’同時使齒輪2、3定位於兩軸承4所 相對向之端面間。軸承4對應眼鏡孔113之内周形狀而呈 與兩個大致圓柱體相鄰接合之外形。於本體u之上方開口 之吸入口 111、於下方開口之吐出口 112分別與眼鏡孔113 連通。另外，於本體Π兩侧分別安裝前蓋12、後蓋丨3而 閉止眼鏡孔113。前蓋12中穿設有用以插通驅動齒輪2之 齒輪軸21之前端部位（與旋轉驅動齒輪2、3之發動機相 連接）的軸孔123。 I295^fdoc 驅動齒輪2以及從動齒輪3構成螺旋齒輪。但對杏幸人 2、3之齒形炎無特別限疋。可為漸開線齒形，亦可為^他 種類之齒形，例如是如同SHIMACLOID(商標名）之不奋產 生封閉現象之一點連續接觸齒形。又，齒輪2、3可與:自 之齒輪軸21、31 —體形成，亦可未一體成型。 於具有上述構成之回輪汞T，根據本實施形態，將對 抗驅動齒輪2以及從動齒輪3所產生之軸向推力並抵消节 軸向推力之流體壓力施加於齒輪軸21、31的軸端。 μ 具體而言，於外殼1上設置自吐出侧向齒輪轴21、31 之軸端側導入高壓流體之導入路121、131，使經由該導入 路121、131導入之流體壓力與軸向推力相平衡。旋轉驅動 齒輪2、3時，驅動齒輪2產生向後方之軸向推力。對此， 於後蓋13之内面即面向本體11後向面之前向面形成有底 槽狀導入路131 ’藉由向導入路131流入之流體的壓力: 齒輪軸21後侧之軸端面推壓。並且，從動齒輪3產生朝二 前^之軸向推力。對此，於前蓋12之内面即面向本體^ 之前向面之後向面形成有底槽狀導入路121，藉由向^入 路⑵流入之流體的壓力向齒輪軸3!前側之轴:黑面推^ 導入路121、131自成為齒輪2、3之齒頂圓更偏外 側的特定部位向齒輪軸2卜31之軸端面附近延伸。齿輪轴 4之反錄2、3面‘ 山、、、=¥入路12卜131流入之流體進入轴承4 =° Wv路121、131需要連通於泵之吐 = 例中，設置貫穿存在於本體n之後向面以及前向面 1295氣 之内周面之間的隔壁之分流路〗14，使該分流路Π4 之終端於臨近導入路121、131之位置處開口，藉此使導入 路121、131連通於吐出侧。I29533^fd0c IX. Description of the invention: [Technical field to which the invention pertains] In particular, it relates to the transfer of high-pressure, high-viscosity fluids, and [previously] self-priming fluids by rotating the gears of (four) The gear u, usually using an involute (i-tute) spur gear (= 1), is easy to cut due to the involute tooth profile, and the measurement of the finished dimension of the tooth profile is also flat and easy, so that high precision can be obtained. Gears. Another-aspect' is the involute spur gear with fluid closure. The two == middle 'in the rotation there are two sets of teeth intermeshing period; and the power wave», _« will lead to the production of money. The harm of the sub-closed phenomenon is more pronounced when the fluid viscosity or the inhalation of the transferred force is higher. Therefore, it is difficult to use a pump with a surface pressure and a high viscosity fluid. It is difficult to use an involute spur gear. If a helical gear (hdkal gea〇) is used, the I force of the '__lang phenomenon wheel body is not changed. Sharp, ^ does not slip, can also suppress (four) sound or vibration." il mouth is also relatively, however, the helical gear is axially pushed in the rotation: the two coffee faces are smashed in the direction of the mammoth and the second will also cause burning. 'Using the offset axial thrust 5 聪 Ro Ro Ro Ro Ro doc doc doc doc doc doc doc doc 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 齿轮 齿轮 齿轮 齿轮 齿轮 齿轮 齿轮 齿轮 齿轮Most of the time is to join the two helical gears of η to become a herringbone gear. However, if the second::: the gear and the gear shaft must be different members. Therefore, the key and the keyway for combining the gear and the gear shaft are not the same. The shape of the gear is large and the gear or the axle is also increased in the diameter direction. The invention is intended to be realized. The present invention does not use a herringbone gear, but a gear pump for a pressurized, high-viscosity fluid. Body into the side 'two: 屮By the rotation of the meshing helical gear, the flow is set from the discharge side to the second tooth ===, and the negative influence of == low = because the thread condition can be guaranteed. In addition, if it is further set to adjust; ^丄::The gear pump of the fluid. The continuous pressure of the body pressure ,μ, θϊ is required for the flow of the fluid flowing in the ν path: the adjustment of the whole valve is used to offset the axial direction, the pump of the body It is particularly effective. The apparent viscosity of the non-cow is also changed. The change rate of the cutting rate is changed. Therefore, the axial thrust assumed in the design stage is not consistent with the axial thrust actually generated by the 6 1295 gas. It is difficult to determine in advance the fluid pressure introduced through the introduction path, and it is preferable to adjust the fluid when it is actually rotated. Further, it is preferable to set the measurement in the above-mentioned guide for the same reason. The pressure gauge of the fluid pressure of the fluid. If the gears and the gear shafts corresponding to the gears are integrally formed, it contributes to the miniaturization of the pump. When the herringbone gear is used, if the shaft is formed integrally, then Gear specifications in gear machining steps In the present invention, the (four) spur gear is set to an optimum value without the plucking angle. The axle body is formed 'and the twisted side port is allowed to be inserted into the shaft end side via the above-mentioned introduction path. The fluid flows into the suction and forms a groove for lubricating the staged body on the inner circumference of the bearing that bears the gear shaft; and the groove is more connected to the introduction path, and the axial weighting balance can be simultaneously realized. i Rotating teeth: The axial direction of the pinion is dirty, and the inner surface is closed to the inner surface of the main body and the inner surface of the cover to form the introduction path. The adjustment cap force gauge can be set. Further, the steps are simplified. The rear dish also helps the pump assembly. According to the rabbit, the gear pump suitable for transferring high and high viscosity fluids can be realized without using the herringbone gear. [Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The gear pump of this embodiment shown in Figs. 1 to 3 is used for high-pressure pressure-feeding of molten resin and other high molecular polymers in, for example, a petroleum plant or a chemical plant. The gear pump is a so-called external gear pump in which the gear 2 and the driven gear 3 are driven in the inner space of the outer casing 1 to be engaged, and the two gears 2 and 3 are rotationally driven to be retained in the slots. The fluid is transferred from the suction side to the pumping side of the discharge side. In fact, the suction side is located above, and the outlet side is located below, and a tank in which molten trees such as molten moon is stored directly above the suction port 1U is provided, and the molten resin in the storage tank is sucked into the outlet, and the outlet is discharged from the discharge port. 112 spits out at the required discharge pressure. The outer casing 1 has a body 11, a front cover 12, and a rear cover 13 as members. A lens hole that does not penetrate in the front-rear direction is inserted into the main body 11, and the gears 2, 3, the gear shafts 21, 31, and the bearing 4 are accommodated in the eyeglass hole 113. Specifically, the bearing 4 is disposed at the front end portion of the eyeglass hole 113 to rotatably support the gear shafts 21, 31' while positioning the gears 2, 3 between the opposite end faces of the two bearings 4. The bearing 4 corresponds to the inner peripheral shape of the eyeglass hole 113 and is formed to be adjacent to the two substantially cylindrical bodies. The suction port 111 opened above the main body u and the discharge port 112 opened at the lower side communicate with the eyeglass holes 113, respectively. Further, the front cover 12 and the rear cover 3 are attached to both sides of the main body to close the eyeglass holes 113. A shaft hole 123 through which a front end portion of the gear shaft 21 of the drive gear 2 is inserted (connected to the engine of the rotary drive gears 2, 3) is bored in the front cover 12. The I295^fdoc drive gear 2 and the driven gear 3 constitute a helical gear. However, there is no special restriction on the tooth disease of Xing Xingren 2,3. It can be an involute tooth shape or a tooth shape of the type, for example, a continuous contact tooth shape like SHIMACLOID (trade name). Further, the gears 2, 3 may be formed integrally with the gear shafts 21, 31 or may not be integrally formed. According to the present embodiment, the return pressure of the returning wheel mercury T having the above-described configuration is applied to the axial ends of the gear shafts 21 and 31 by the fluid pressure against the axial thrust generated by the drive gear 2 and the driven gear 3 and canceling the thrust in the pitch direction. . Specifically, the casing 1 is provided with introduction paths 121 and 131 for introducing high-pressure fluid from the axial end sides of the discharge side gear shafts 21 and 31, and the fluid pressure and the axial thrust force introduced through the introduction paths 121 and 131 are balance. When the gears 2, 3 are rotationally driven, the drive gear 2 generates an axial thrust toward the rear. On the other hand, the inner surface of the rear cover 13 faces the front surface of the main body 11 and faces the front surface of the main body 11 to form a bottomed groove-shaped introduction path 131'. The pressure of the fluid flowing into the introduction path 131: the axial end surface of the rear side of the gear shaft 21 is pressed. . Further, the driven gear 3 generates an axial thrust toward the front. On the other hand, the inner surface of the front cover 12, that is, the front surface of the front surface facing the main body, is formed with a bottomed groove-shaped introduction path 121, and the pressure of the fluid flowing into the path (2) toward the front side of the gear shaft 3! The surface introduction electrodes 121 and 131 extend from the vicinity of the axial end faces of the gear shafts 2 to 31 from the specific portions which become the outer side of the addendum circle of the gears 2 and 3. The reverse of the gear shaft 4, 2, 3 faces 'mountain,,, =¥, 12, 131, the fluid flowing into the bearing 4 = ° Wv, 121, 131 need to communicate with the pump spit = in the example, the setting runs through the body a bypass passage 14 of the partition wall between the rearward facing surface and the inner circumferential surface of the forward surface 1295, and the end of the branching passage 4 is opened at a position adjacent to the introduction passages 121 and 131, whereby the introduction path 121, 131 is connected to the discharge side.
又’於軸承4内周設有為潤滑齒輪軸21、31與軸承4 之邊界面而流入少許流體之凹槽41。凹槽41至少於軸承4 之齒輪2、3侧端面開口，且沿軸心方向延伸至軸承4之反 歯輪2、3側之端面附近，可使滯留於齒輪2、3之齒槽中 的一部分流體流入。Further, a groove 41 for injecting a small amount of fluid into the boundary surface of the gear shafts 21, 31 and the bearing 4 is provided on the inner circumference of the bearing 4. The groove 41 is open at least on the side faces of the gears 2, 3 of the bearing 4, and extends in the axial direction to the vicinity of the end faces of the backing wheels 2, 3 of the bearing 4, so that it can be retained in the slots of the gears 2, 3. A part of the fluid flows in.
使經由導入路121、131而導入至軸端側之流體以及經 由凹槽41而導入至軸承4内之流體最終回流至泵吸入侧。 因此，於後盍13以及前蓋12之内面形成有底槽狀回流路 122、132。回流路122、132分別於後蓋13、前蓋12中以 相對於各齒輪軸21、31呈大致八字型之方式設置兩條。回 流路122、132自#輪軸2：1、31之軸端面附近向成為齒輪 2、3之齒頂圓更偏外周側的特定部位延伸。進而，兩條回 流路122、132中之-條與導入路m、131相連。回流路 122、132需要連通於泵吸入侧，於圖示例中，設置貫穿存 在於本體11之前向面以及後向面與吸入口 lu之内周面之 間的隔壁之合流路U5，使該合流路115之終端於臨近回 流路122、132之位置處開口，藉此使回流路⑵m盥 吸入側相連通。 /' 分別將齒輪栗之理論扭矩設為Tth，實際扭矩 效率設為η，齒輪2、3每一次旋轉之吐出量机^ 輪2、3之外徑設為D，齒寬設為B，齒輪模數;;為二二 10 1295¾¾ if.doc 數設為Z，節圓直徑設為A,螺旋齒 β ’吸入壓力與吐出壓力之壓差設為p，之扭^設為 之車由向推力設為F。實際扭矩τ』τ / #輪丄2、3所產生 矩Tth與損耗扭矩之和。關於理論才丑=換^即理論扭 vj：x；^ 根據上式可知軸向推力F與壓差p 僅考慮到經由凹槽41而流通於轴 ^ 時，則通常將作用於齿㈣Α91 Μ Η内之札月用流體 定為猶大於吸入壓力:之，“體壓力設 差成正_基礎上，若將回;路丨:::: 向推力造成之不良影響怕，則可排除或降低軸 化則物=頓流體若剪切速率產生變 可：實際，導 以及導入二輪泵中，設有用以調整分流路m 5,以及用以麵流體===:_ 藉咖而使閥芯(間體)進退:力手=;=如 Π95 獨 fdoc 裝設於後蓋13:前蓋12上。調整閱5之閥芯中形成有朝 向前端徐徐鮮之錐形部，可藉自㈣_部麵於分流 路114之開口（閥座）而完全閉合，或可藉由使錐形部偏 離分流路114之開口而調整越壓力 後蓋13、前蓋η上。其中對壓力計6之種二 無特別限定。 根據本實施形態’於藉由喊合之螺旋齒輪2、3之 而將流體自吸入側向吐出側移送之齒輪泵中，設置自吐出 侧向齒輪轴21、31之軸端侧導入流體之導入路1^、〖Μ， 將克服螺旋#輪2、3所產生之軸向推力之流體壓力施加於 軸端，故而可不㈣於扭轉角大小而排 力 之不良影響。因可保證扭轉角設計之自由:=力 轉角設定為適當大小而避免封閉現象，= ^ :杻 格條件。因此’可使用螺旋齒輪 現、=應气種規 高黏度流體的齒輪系。輪3 ^適於移送高壓、 因進用以破上述導人路121、131中所产通之 流體之流祕力的_相5以 f , 中所流=之流體壓力的壓力計6, =2= 壓力，同時撫作調整閥5， Ti}工級體 充分大小。因為_ ^為抵雜向推力所需要之 條:下調=閥5，即;吏：= 二某:轉 整5周整閥5。㉛，於泵操作運轉時不ΐ要煩雜:The fluid introduced to the shaft end side via the introduction paths 121, 131 and the fluid introduced into the bearing 4 via the groove 41 are finally returned to the pump suction side. Therefore, bottom groove-shaped return paths 122 and 132 are formed on the inner surface of the rear cymbal 13 and the front cover 12. The return passages 122 and 132 are provided in the rear cover 13 and the front cover 12 in a substantially splayed shape with respect to the respective gear shafts 21 and 31, respectively. The return paths 122 and 132 extend from the vicinity of the axial end faces of the #-axes 2:1 and 31 to specific portions which are the outer circumference sides of the addendum circles of the gears 2 and 3. Further, among the two return paths 122 and 132, the strips are connected to the introduction paths m and 131. The return passages 122 and 132 are required to communicate with the suction side of the pump. In the illustrated example, a joining passage U5 penetrating through the partition wall between the front surface of the main body 11 and the inner circumferential surface of the rear surface and the suction port lu is provided. The terminal of the joining path 115 is opened at a position adjacent to the return paths 122, 132, whereby the return path (2) m is connected to the suction side. /' Set the theoretical torque of the gear to Tth, the actual torque efficiency to η, and the gears 2, 3 for each rotation. The outer diameter of the wheels 2, 3 is set to D, and the tooth width is set to B. Modulus;; for 2 2 10 12953⁄43⁄4 if.doc is set to Z, the pitch diameter is set to A, the spiral tooth β 'the suction pressure and the discharge pressure are set to p, and the twist is set to the vehicle. Set to F. The sum of the moment Tth generated by the actual torque τ τ / # rims 2, 3 and the loss torque. According to the above formula, it can be seen that the axial thrust F and the differential pressure p are only considered to flow through the groove 41 through the groove 41, and usually will act on the tooth (four) Α 91 Μ Η The fluid used in the month is determined to be greater than the suction pressure: "the body pressure is set to be positive." If it is to be returned, the path is: if the pressure is not enough, the shafting can be eliminated or reduced. Then, if the shearing rate of the fluid is changed, it can be changed: in actual, guided and introduced into the two-wheel pump, it is provided to adjust the splitting path m 5, and to use the surface fluid ===: _ to make the valve core (intermediate body) ) Advance and retreat: force hand =; = Π 95 alone fdoc is installed on the back cover 13: the front cover 12. The valve core of the adjustment read 5 has a tapered portion that is gradually toward the front end, which can be borrowed from (4) _ faceted The opening (satellite) of the branching path 114 is completely closed, or the pressure-receiving back cover 13 and the front cover η can be adjusted by shifting the tapered portion away from the opening of the branching path 114. According to the present embodiment, in the gear pump that transfers fluid from the suction side to the discharge side by means of the helical gears 2 and 3 The introduction path for introducing the fluid from the axial end sides of the discharge side gear shafts 21, 31 is set, and the fluid pressure that overcomes the axial thrust generated by the spiral # wheels 2, 3 is applied to the shaft end, so it is not necessary (four) The adverse effect of the displacement angle on the torsion angle. The freedom of the design of the torsion angle can be guaranteed: = the force angle is set to an appropriate size to avoid the closing phenomenon, = ^ : the condition of the grid. Therefore, the use of the helical gear can be used. A gear train with a high-viscosity fluid. The wheel 3 ^ is suitable for transferring high pressure, and the flow of the fluid used to break the flow of the fluid introduced in the above-mentioned guides 121, 131 is 5, f, in the flow = The pressure of the fluid pressure gauge 6, = 2 = pressure, while adjusting the valve 5, Ti} the full size of the working body. Because _ ^ is the required strip for the thrust: down = valve 5, ie; = Two: Turning the whole valve to 5.31 for 5 weeks, it is not complicated when the pump is running:
因為由單一構件槿成H 冓成各4 2、3與對應於該齒輪2、 12953 泰· 3之齒輪轴21、31，故而有助於泵之小型化。 設置使經由上述導人路12ι、13ι導人至軸端側之流體 向吸入側回流之回流路122、132,且於承受童輪軸2卜31 之軸承4之内周上形成用以流入流體進行潤滑之凹槽4卜 使該凹槽41與上述回流路122、132以及上述導入路\21、 131相連通，故而可同時實現軸向推力之平衡與軸承4之 潤滑。 泵之外殼1以沿齒輪軸21、31之軸心方向貫通並收納 螺旋齒輪2、3、齒輪軸21、31以及軸承4之本體u與前 後閉止上述本體11而使内面與各齒輪軸21、31之軸端相 對置的前蓋12以及後蓋13作為構件，於上述前蓋12、上 述後盖13各自之内面形成上述導入路I]〗、I)〗以及上述 回流路122、132，故而不會招致無用結構之複雜化。又， 可將調整閥5或壓力計6裝設於前蓋12、後蓋13，亦有助 於泵組裝步驟之簡便化。 再者’本發明並不限定於以上詳細闡述之實施形態。 _ 特別是本發明之適用對象並不限定於用以壓送高壓、高黏 度流體之泵。對於所有採用螺旋齒輪之泵皆可使用本發明。 其他各部分之具體構成並不限定於上述實施形態，於 不脫離本發明主旨之範圍内可作各種變形。 【圖式簡單說明】 圖1是表示本發明之一實施形態之齒輪泵的侧剖面 圖。 圖2是表示本發明之一實施形態之齒輪栗之侧剖面 13 I29552^f<doc 圖。 圖3是表示本發明之一實施形態之齒輪泵的分解立體 圖。 【主要元件符號說明】 1 :外殼 2:驅動齒輪 3:從動齒輪 4 :軸承 5 :調整閥 6 :壓力計 11 ： 本體 12 ： 前蓋 13 ： 後蓋 21 > 31 :齒輪軸 41 ： 凹槽 111 :吸入口 112 :吐出口 113 :眼鏡孔 114 :分流路 115 :合流路 121 、131 :導入路 122 、132 :回流路 123 :軸孔 14Since the single member is folded into H to form the respective 4, 2 and 3, and the gear shafts 21 and 31 corresponding to the gears 2, 12953, and 3, it contributes to miniaturization of the pump. A return path 122, 132 for recirculating the fluid to the suction side via the above-described guide path 12ι, 13ι is provided, and is formed on the inner circumference of the bearing 4 bearing the child shaft 2b for inflowing fluid The groove 4 for lubrication communicates with the return passages 122 and 132 and the introduction paths \21 and 131, so that the balance of the axial thrust and the lubrication of the bearing 4 can be simultaneously achieved. The outer casing 1 of the pump penetrates and houses the helical gears 2, 3, the gear shafts 21, 31, and the main body u of the bearing 4 in the axial direction of the gear shafts 21, 31, and closes the main body 11 in the front-rear direction to the inner surface and the respective gear shafts 21, The front cover 12 and the rear cover 13 facing each other at the axial end of the 31 are formed as members, and the introduction paths I], I) and the return paths 122 and 132 are formed on the inner surfaces of the front cover 12 and the rear cover 13, respectively. Will not incur the complexity of useless structures. Further, the adjustment valve 5 or the pressure gauge 6 can be attached to the front cover 12 and the rear cover 13, which also contributes to the simplification of the pump assembly step. Further, the present invention is not limited to the embodiments described in detail above. In particular, the object to which the present invention is applied is not limited to a pump for pumping a high-pressure, high-viscosity fluid. The invention can be used with all pumps that employ helical gears. The specific configuration of the other parts is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit and scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side sectional view showing a gear pump according to an embodiment of the present invention. Fig. 2 is a side view showing a side section of a gear pump according to an embodiment of the present invention. Fig. 3 is an exploded perspective view showing a gear pump according to an embodiment of the present invention. [Main component symbol description] 1 : Case 2: Drive gear 3: Drive gear 4 : Bearing 5 : Adjustment valve 6 : Pressure gauge 11 : Main body 12 : Front cover 13 : Rear cover 21 > 31 : Gear shaft 41 : Concave Groove 111: suction port 112: discharge port 113: eyeglass hole 114: branching path 115: joining path 121, 131: introduction path 122, 132: return path 123: shaft hole 14