JP5957735B2 - Hydraulic circuit for lifting the harvesting part of the combine - Google Patents

Hydraulic circuit for lifting the harvesting part of the combine Download PDF

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JP5957735B2
JP5957735B2 JP2012145655A JP2012145655A JP5957735B2 JP 5957735 B2 JP5957735 B2 JP 5957735B2 JP 2012145655 A JP2012145655 A JP 2012145655A JP 2012145655 A JP2012145655 A JP 2012145655A JP 5957735 B2 JP5957735 B2 JP 5957735B2
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hydraulic
oil
throttle
check valve
pilot
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JP2014009728A (en
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秀樹 兼述
秀樹 兼述
鎌田　稔
稔 鎌田
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Kanzaki Kokyukoki Manufacturing Co Ltd
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Kanzaki Kokyukoki Manufacturing Co Ltd
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Priority to CN201310203741.5A priority patent/CN103511370B/en
Priority to KR1020130047540A priority patent/KR101755064B1/en
Priority to TW102118239A priority patent/TWI583298B/en
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    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01B—SOIL WORKING IN AGRICULTURE OR FORESTRY; PARTS, DETAILS, OR ACCESSORIES OF AGRICULTURAL MACHINES OR IMPLEMENTS, IN GENERAL
    • A01B63/00—Lifting or adjusting devices or arrangements for agricultural machines or implements
    • A01B63/02—Lifting or adjusting devices or arrangements for agricultural machines or implements for implements mounted on tractors
    • A01B63/10—Lifting or adjusting devices or arrangements for agricultural machines or implements for implements mounted on tractors operated by hydraulic or pneumatic means
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01B—SOIL WORKING IN AGRICULTURE OR FORESTRY; PARTS, DETAILS, OR ACCESSORIES OF AGRICULTURAL MACHINES OR IMPLEMENTS, IN GENERAL
    • A01B63/00—Lifting or adjusting devices or arrangements for agricultural machines or implements
    • A01B63/02—Lifting or adjusting devices or arrangements for agricultural machines or implements for implements mounted on tractors
    • A01B63/10—Lifting or adjusting devices or arrangements for agricultural machines or implements for implements mounted on tractors operated by hydraulic or pneumatic means
    • A01B63/1006—Lifting or adjusting devices or arrangements for agricultural machines or implements for implements mounted on tractors operated by hydraulic or pneumatic means the hydraulic or pneumatic means structurally belonging to the tractor
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01D—HARVESTING; MOWING
    • A01D34/00—Mowers; Mowing apparatus of harvesters
    • A01D34/01—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus
    • A01D34/02—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus having reciprocating cutters
    • A01D34/24—Lifting devices for the cutter-bar
    • A01D34/246—Hydraulic lifting devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Environmental Sciences (AREA)
  • Soil Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Harvester Elements (AREA)

Description

本発明は、コンバインの刈取部を昇降させるための油圧回路に関する。   The present invention relates to a hydraulic circuit for raising and lowering a harvesting portion of a combine.

従来、コンバインは、一般に、機体前部に昇降自在の刈取部を装備している。刈取部は、例えば、刈取高さを設定する際には低速で昇降させ、作業終了後又は作業開始前には高速で昇降させたいという要望がある。そのため、刈取部を昇降させる油圧シリンダーを変速可能とする油圧回路が提案されている（例えば、特許文献１）。   Conventionally, a combine is generally equipped with a reaper that can be raised and lowered at the front of the body. For example, there is a demand for the mowing unit to move up and down at a low speed when setting the cutting height and to move up and down at a high speed after the work is finished or before the work is started. For this reason, a hydraulic circuit has been proposed that makes it possible to change the speed of a hydraulic cylinder that raises and lowers the cutting part (for example, Patent Document 1).

この特許文献１の油圧回路は、刈取部を下降させる際には、並列に接続した流量の異なる電磁式開閉弁を選択操作して油圧シリンダーから排出される作動油の流量を制御する一方、刈取部を上昇させる際には、高速上昇時はポンプからの作動油の全流量を油圧シリンダーに供給し、低速上昇時は、前記電磁式開閉弁の少なくとも一方から作動油の一部を逃すブリードオフ回路に切り換えて、油圧シリンダーに供給する作動油の流量を制御している。   The hydraulic circuit disclosed in Patent Document 1 controls the flow rate of hydraulic oil discharged from a hydraulic cylinder by selecting and operating electromagnetic open / close valves with different flow rates connected in parallel when lowering the cutting unit. When raising the part, the full flow rate of hydraulic oil from the pump is supplied to the hydraulic cylinder when rising at high speed, and bleed-off that releases part of the hydraulic oil from at least one of the electromagnetic on-off valves when rising at low speed. Switching to the circuit controls the flow rate of hydraulic oil supplied to the hydraulic cylinder.

しかしながら、上記特許文献１の油圧回路は、刈取部の低速上昇させるためにいわゆるブリードオフ回路によって油圧シリンダーを制御しているため、刈取部にかかる負荷が大きくなると、それに応じて作動油の圧力が上昇し、逃げ流量が増加する結果、上昇流量が大幅に下落し、上昇速度が大幅に低下する。   However, since the hydraulic circuit of Patent Document 1 controls the hydraulic cylinder by a so-called bleed-off circuit in order to raise the cutting part at a low speed, when the load applied to the cutting part increases, the pressure of the hydraulic oil is correspondingly increased. As a result, the escape flow rate increases, and as a result, the ascending flow rate decreases significantly and the ascending speed decreases significantly.

また、上記油圧回路では、低速上昇時に油圧シリンダーからドレンされる作動油は、流量を制限する電磁式開閉弁を通過する際の摩擦により温度が上昇する。作動油の粘度は温度が上昇するほど低くなるため、温度が上昇するほど作動油の粘性抵抗が減少し、作動油が電磁開閉弁を通過しやすくなる。一方、刈取部に負荷がかかると作動油の圧力も上昇するため、温度上昇した状態で刈取部に負荷がかかると、負荷が増すほど、電磁式開閉弁の油路を通過しやすくなり、その結果、刈取部に負荷がかかるほど、作動油の逃げ流量が増して油圧シリンダーに供給される流量が減るため、刈取部の上昇速度が遅くなり、刈取部にかかる負荷による上昇速度のバラツキが大きい。   Further, in the above hydraulic circuit, the temperature of the hydraulic oil drained from the hydraulic cylinder when rising at a low speed rises due to friction when passing through an electromagnetic on-off valve that limits the flow rate. Since the viscosity of the hydraulic oil decreases as the temperature increases, the viscosity resistance of the hydraulic oil decreases as the temperature increases, and the hydraulic oil easily passes through the electromagnetic on-off valve. On the other hand, when the load is applied to the cutting part, the pressure of the hydraulic oil also increases, so when the load is applied to the cutting part with the temperature rising, the more the load is increased, the easier it is to pass through the oil passage of the electromagnetic on-off valve. As a result, the more the load is applied to the cutting part, the greater the escape flow rate of the hydraulic oil and the less the flow rate supplied to the hydraulic cylinder. Therefore, the rising speed of the cutting part becomes slow, and the variation in the rising speed due to the load on the cutting part is large. .

また、アイドリング時等でエンジンが低速回転のとき、刈取部を低速上昇させようとしても、ブリードオフ回路では、油圧ポンプからの吐出流量が少ないため、逃げ流量を上回る流量が確保できず、低速上昇させることができない。   In addition, when the engine is rotating at low speed, such as when idling, the bleed-off circuit has a low discharge flow rate from the hydraulic pump, so the flow rate exceeding the escape flow rate cannot be secured and the low speed increase I can't let you.

さらに、流量の異なる２つの電磁開閉弁を選択して、刈取部の昇降速度を変更する構成であり、低速上昇用と低速下降用の絞りを共通で用いるため、コンバイン本機へのマッチングが困難な場合がある。   Furthermore, it is a configuration that changes the lifting speed of the mowing unit by selecting two electromagnetic on-off valves with different flow rates. Since the throttle for low-speed rise and low-speed drop is used in common, it is difficult to match the combine machine. There are cases.

そこで、上記問題を解決するため、供給油路に設けた開閉可能な切換弁と並列に供給油量制限用絞りを接続し、低速上昇時には、供給油路に設けた切換弁を閉に切り換えることで、油圧シリンダーに供給される作動油を供給油量供制限用絞りによって制御されるメーターイン回路に切り換えることを可能にした油圧回路が提案されている（特許文献２）。   Therefore, in order to solve the above problems, a supply oil amount restriction throttle is connected in parallel with an openable / closable switching valve provided in the supply oil passage, and the changeover valve provided in the supply oil passage is switched to a closed state at the time of low speed rise. Thus, there has been proposed a hydraulic circuit capable of switching the hydraulic oil supplied to the hydraulic cylinder to a meter-in circuit controlled by a supply oil amount restriction throttle (Patent Document 2).

特開平６−１１３６０３号公報JP-A-6-113603 特許第４９９４２９６号公報Japanese Patent No. 4994296

上記特許文献２に開示された油圧回路によれば、作動油の逃げ流量による刈取部の上昇速度変動が抑制されるとともに、エンジンの低速回転時でも低速上昇が可能となるという優れた効果を発揮し得るが、回路構成によっては、特にアイドリング時等で作動油流量が少なく油温が高い場合等に、刈取部を高速で下降させる際に、高速下降操作開始時から実際に刈取部の下降が始まる迄に若干のタイムラグがあった。   According to the hydraulic circuit disclosed in the above-mentioned Patent Document 2, fluctuations in the ascending speed of the cutting part due to the escape flow rate of the hydraulic oil are suppressed, and an excellent effect is achieved in that the ascending speed can be increased even when the engine rotates at a low speed. However, depending on the circuit configuration, especially when idling, etc., when the hydraulic oil flow rate is low and the oil temperature is high, etc. There was a slight time lag before it started.

そこで、本発明は、上記特許文献２に開示された油圧回路を更に改良し、刈取部を高速で下降させる際に生じるタイムラグを短縮することができるコンバインの刈取部昇降用油圧回路を提供することを主たる目的とする。   Therefore, the present invention provides a hydraulic circuit for raising and lowering a harvesting part of a combine that can further improve the hydraulic circuit disclosed in Patent Document 2 and reduce a time lag that occurs when the harvesting part is lowered at high speed. Is the main purpose.

本発明者等による鋭意研究の結果、刈取部を高速で下降させる際に生じるタイムラグは、刈取部を高速で下降させる際に、油圧ポンプからの作動油が、低速上昇用に設けた供給油量制限用絞り（第１の絞り）を通ってドレンされる経路が構成されることが原因であることを突き止めた。   As a result of intensive studies by the present inventors, the time lag that occurs when lowering the cutting part at high speed is the amount of hydraulic oil supplied from the hydraulic pump for lowering the speed when lowering the cutting part at high speed. It has been found that this is due to the construction of a path that drains through the restriction aperture (first aperture).

そこで、上記目的を達成するため、本発明に係るコンバインの刈取部昇降用油圧回路は、コンバインの刈取部を昇降させる油圧シリンダーを、オイルタンクから油圧ポンプを介して送られる作動油によって駆動するための油圧回路であって、パイロット圧を利用して前記油圧シリンダーから作動油の逆流を許容するパイロット操作型チェック弁と、給圧一次側ポートと油圧シリンダー作動油路用二次側ポートとを開通させる第１の位置と前記給圧一次側ポートとパイロット圧作動油路用二次側ポートとを開通させるとともに前記油圧シリンダー作動油路用二次側ポートとタンクポートとを開通させる第２の位置と前記給圧一次側ポートおよび前記油圧シリンダー作動油路用二次側ポートを閉じる第３の位置とに切り換え可能な第１の切換弁と、前記第１の切換弁と並列に接続され、前記油圧ポンプから前記油圧シリンダーへ供給される作動油の流量を制限するための第１の絞りと、前記第１の絞りと直列に接続され、前記第１の切換弁が前記第２の位置にあるときに前記第１の絞りを通る作動油を規制して前記パイロット操作型チェック弁のパイロット圧を確保するための抵抗弁と、前記パイロット操作型チェック弁を逆流してドレンされる作動油の流量を制限するための第２の絞りと、前記第２の絞りより小さい流路断面積を備え、ドレンされる作動油の流量を制限するための第３の絞りと、ドレンされる作動油の油路を、前記第３の絞りを通じてドレンされる作動油の油路に選択的に切換可能な第２の切換弁と、を備えることを特徴とする。   Therefore, in order to achieve the above object, the harvesting part raising / lowering hydraulic circuit according to the present invention drives a hydraulic cylinder that raises and lowers the harvesting part of the combine with hydraulic oil sent from an oil tank via a hydraulic pump. A pilot operated check valve that allows the backflow of hydraulic oil from the hydraulic cylinder using a pilot pressure, and a supply pressure primary side port and a hydraulic cylinder hydraulic oil passage secondary side port are opened. A first position to be opened, and a second position to open the supply pressure primary side port and the secondary port for the pilot pressure hydraulic fluid passage, and to open the secondary port for the hydraulic cylinder hydraulic fluid passage and the tank port. And a first switching valve that can be switched to a third position that closes the supply pressure primary side port and the hydraulic cylinder hydraulic oil passage secondary port. A first throttle connected in parallel with the first switching valve, for limiting a flow rate of hydraulic oil supplied from the hydraulic pump to the hydraulic cylinder, and connected in series with the first throttle; A resistance valve for restricting hydraulic fluid passing through the first throttle when the first switching valve is in the second position to ensure a pilot pressure of the pilot operated check valve; and the pilot operated type A second throttle for limiting the flow rate of the hydraulic oil drained by flowing back through the check valve; and a flow passage cross-sectional area smaller than the second throttle, for limiting the flow rate of the drained hydraulic oil And a third switching valve, and a second switching valve capable of selectively switching an oil passage for drained hydraulic oil to an oil passage for draining hydraulic fluid through the third throttle. To do.

前記パイロット操作型チェック弁は、チェック弁本体と、該チェック弁本体が離座可能なシートと、前記チェック弁本体を前記シートに押圧付勢するバネと、前記チェック弁本体と前記シートを介して対向して摺動自在に配置されたパイロットピストンと、を備えることが好ましい。   The pilot operated check valve includes a check valve body, a seat from which the check valve body can be separated, a spring that presses and urges the check valve body against the seat, and the check valve body and the seat. It is preferable to provide a pilot piston which is slidably disposed opposite to each other.

本発明によれば、作動油流量を制限して刈取部の低速上昇させる第１の絞りと直列に抵抗弁を接続することにより、油圧ポンプからの作動油が第１の絞りを通ってドレンされる前に、パイロット操作型チェック弁をパイロット操作により開弁させるので、アイドリング時等で作動油の投入流量が少ない場合であっても、迅速にパイロット操作型チェック弁にパイロット圧を供給し、パイロット操作型チェック弁を開弁させるので、刈取部の高速下降操作時のタイムラグを減少させることができる。   According to the present invention, the hydraulic oil from the hydraulic pump is drained through the first throttle by connecting the resistance valve in series with the first throttle that restricts the hydraulic oil flow rate and raises the cutting part at a low speed. The pilot-operated check valve is opened by pilot operation before starting operation, so pilot pressure can be quickly supplied to the pilot-operated check valve even when the flow rate of hydraulic oil is low, such as when idling. Since the operation type check valve is opened, the time lag at the time of the high-speed lowering operation of the cutting part can be reduced.

一般的なコンバインの要部を示す側面図である。It is a side view which shows the principal part of a general combine. 本発明に係るコンバインの刈取部昇降用油圧回路の一実施形態を示す油圧回路図である。1 is a hydraulic circuit diagram showing one embodiment of a hydraulic circuit for raising and lowering a harvesting part of a combine according to the present invention. 図２の油圧回路が組み込まれた油圧回路ブロックユニットを示す要部断面図である。It is principal part sectional drawing which shows the hydraulic circuit block unit in which the hydraulic circuit of FIG. 2 was integrated. 本発明に係るコンバインの刈取部昇降用油圧回路の変更態様を示す油圧回路図である。It is a hydraulic circuit diagram which shows the change aspect of the harvesting part raising / lowering hydraulic circuit of the combine which concerns on this invention. 本発明に係るコンバインの刈取部昇降用油圧回路の他の変更態様を示す油圧回路図である。It is a hydraulic circuit diagram which shows the other change aspect of the hydraulic circuit for the harvesting part raising / lowering of the combine which concerns on this invention.

本発明に係るコンバインの刈取部昇降用油圧回路の実施形態について、以下に図１〜５を参照して説明する。なお、全図及び全実施例を通じて、同様の構成部分には同符号を付した。   DESCRIPTION OF EMBODIMENTS Embodiments of a hydraulic circuit for lifting and lowering a harvesting portion of a combine according to the present invention will be described below with reference to FIGS. In addition, the same code | symbol was attached | subjected to the same component through all the figures and all the Examples.

先ず、コンバインの概略構成について説明すると、一般的なコンバインは、図１に示すように、前部に刈取部１を備えており、刈取部１は、油圧シリンダー２の駆動によって上下昇降する。油圧シリンダー２は、単動式の油圧シリンダーが採用され得る。   First, the general configuration of the combine will be described. As shown in FIG. 1, a general combine includes a cutting unit 1 at the front, and the cutting unit 1 moves up and down by driving a hydraulic cylinder 2. The hydraulic cylinder 2 can be a single-acting hydraulic cylinder.

図２は、本発明に係るコンバインの刈取部昇降用油圧回路の一実施形態を示す油圧回路図である。   FIG. 2 is a hydraulic circuit diagram showing an embodiment of the hydraulic circuit for raising and lowering the harvesting part of the combine according to the present invention.

油圧回路は、基本的に、オイルタンク３から油圧ポンプ４によって油圧シリンダー２のピストン室２ａに作動油を供給し、ピストン２ｂを移動させて、ピストンロッド２ｃに連結している刈取部１（図１参照。以下同じ。）を上昇させる一方、ピストン室２ａの作動油をオイルタンク３にドレンすることにより、ピストン２ｂを元の位置に戻し、刈取部１を下降させる。   The hydraulic circuit basically supplies hydraulic oil from the oil tank 3 to the piston chamber 2a of the hydraulic cylinder 2 by the hydraulic pump 4, moves the piston 2b, and is connected to the piston rod 2c (see FIG. 1). 1), the piston 2b is returned to its original position and the cutting part 1 is lowered by draining the hydraulic oil in the piston chamber 2a to the oil tank 3.

油圧ポンプ４と油圧シリンダー２との間には、油圧ポンプ４から順に、油路５ａ、電磁式切換弁６、油路５ｂ、第１の切換弁７、油路５ｃ、パイロット操作型チェック弁１１、油路５ｄ、スローリターン弁１２、油路５ｅが接続されるとともに、油路５ｂ及び油路５ｃにバイパス油路８が接続され、該バイパス油路８に介在され第１の切換弁７と並列接続された第１の絞り９と、バイパス油路８に第１の絞り９と直列に接続された抵抗弁１０とが接続されている。   Between the hydraulic pump 4 and the hydraulic cylinder 2, in order from the hydraulic pump 4, an oil passage 5a, an electromagnetic switching valve 6, an oil passage 5b, a first switching valve 7, an oil passage 5c, and a pilot operated check valve 11 are arranged. The oil passage 5d, the slow return valve 12, and the oil passage 5e are connected, and the bypass oil passage 8 is connected to the oil passage 5b and the oil passage 5c, and the first switching valve 7 is interposed in the bypass oil passage 8. A first throttle 9 connected in parallel and a resistance valve 10 connected in series with the first throttle 9 are connected to the bypass oil passage 8.

抵抗弁１０は、シーケンス弁の一種であり、一次側のバイパス油路８が設定圧を超えるとバイパス油路８を開通させる。パイロット操作型チェック弁１１は、外部パイロットポートを備え、該外部パイロットポートに通じるパイロット圧作動油路１１ａに所定のパイロット圧の作動油が供給されるとパイロット操作型チェック弁１１のチェック弁本体１１ｂ（図３参照）を開き、作動油の逆流を許容する。抵抗弁１０の設定圧は、パイロット操作型チェック弁１１のパイロット圧より大きく設定されている。スローリターン弁１２は、チェック弁１２ａと、チェック弁１２ａに並列接続された第２の絞り１２ｂが内蔵されている。   The resistance valve 10 is a kind of sequence valve, and opens the bypass oil passage 8 when the primary bypass oil passage 8 exceeds a set pressure. The pilot operated check valve 11 includes an external pilot port, and when hydraulic fluid having a predetermined pilot pressure is supplied to a pilot pressure hydraulic fluid passage 11a that communicates with the external pilot port, the check valve main body 11b of the pilot operated check valve 11 is provided. Open (see Fig. 3) and allow backflow of hydraulic oil. The set pressure of the resistance valve 10 is set higher than the pilot pressure of the pilot operated check valve 11. The slow return valve 12 includes a check valve 12a and a second throttle 12b connected in parallel to the check valve 12a.

なお、「絞り」の語は、流れの断面積を減少し、油路又は流体通路内に抵抗をもたせる機構のことであり、固定絞り、可変絞り、絞り弁、絞り切換弁などを含む。   The term “throttle” refers to a mechanism that reduces the cross-sectional area of the flow and provides resistance in the oil passage or fluid passage, and includes a fixed throttle, a variable throttle, a throttle valve, a throttle switching valve, and the like.

電磁式切換弁６は、図示例では、一対のソレノイド６ａ、６ｂ及びバネ６ｃ、６ｄを備える、オープンセンターの４ポート３位置切換弁である。電磁式切換弁６は、非励磁状態では、バネ６ｃ、６ｄの釣り合いによって、図２に示す中立位置にある。中立位置では、油圧ポンプ４から油路５ａに圧送される作動油は、油路１３ａ、１３ｂ、１４を通じてオイルタンク３へドレンされる。一方のソレノイド６ａを励磁すると、油路５ａ、５ｂが開通する。他方のソレノイド６ｂを励磁すると、油路５ａと油路１５とが開通し、油圧ポンプ４から油路５ａに圧送される作動油は、油路１５を通じてコンバインに搭載されているグレンタンク昇降機やオーガー昇降部等の他の作業装備を駆動する油圧アクチュエータ（図示せず。）に供給される。   In the illustrated example, the electromagnetic switching valve 6 is an open center 4-port 3-position switching valve including a pair of solenoids 6a, 6b and springs 6c, 6d. In the non-excited state, the electromagnetic switching valve 6 is in the neutral position shown in FIG. 2 due to the balance of the springs 6c and 6d. In the neutral position, the hydraulic oil pumped from the hydraulic pump 4 to the oil passage 5a is drained to the oil tank 3 through the oil passages 13a, 13b, and 14. When one solenoid 6a is excited, the oil passages 5a and 5b are opened. When the other solenoid 6b is energized, the oil passage 5a and the oil passage 15 are opened, and the hydraulic oil pressure-fed from the hydraulic pump 4 to the oil passage 5a passes through the oil passage 15 through the Glen tank elevator or auger mounted on the combine. It is supplied to a hydraulic actuator (not shown) that drives other work equipment such as a lifting unit.

第１の切換弁７は、図示例では、一対のソレノイド７ａ、７ｂと一対のバネ７ｃ、７ｄを備える電磁弁であって、給圧一次側ポートＰ、タンクポートＴ、パイロット圧作動油路用二次側ポートＡ、油圧シリンダー作動油路用二次側ポートＢを備える、ポンプクローズドセンターの４ポート３位置切換弁である。第１の切換弁７は、ソレノイド７ａ、７ｂが非励磁の時は、バネ７ｃ、７ｄによって油路５ｂ、５ｃ間のポートＰＢ間を閉じる中立位置（図２に示された位置）に付勢されている。一方のソレノイド７ａを励磁することにより、第１の切換弁７は、前記中立位置から、油路５ｂ、５ｃ間をポートＰからポートＢへの油路を開通させる位置に切り換えられる。他方のソレノイド７ｂを励磁すると、ポートＰからポートＡへの油路を開通させるとともにポートＢからポートＴへの油路を開通させる位置に切り換えられる。   In the illustrated example, the first switching valve 7 is a solenoid valve including a pair of solenoids 7a and 7b and a pair of springs 7c and 7d, and is used for a supply pressure primary side port P, a tank port T, and a pilot pressure hydraulic fluid path. It is a 4 port 3 position switching valve of a pump closed center provided with the secondary side port A and the secondary side port B for hydraulic-cylinder hydraulic fluid paths. When the solenoids 7a and 7b are not energized, the first switching valve 7 is biased to a neutral position (position shown in FIG. 2) that closes the port PB between the oil passages 5b and 5c by the springs 7c and 7d. Has been. By energizing one solenoid 7a, the first switching valve 7 is switched from the neutral position to a position where the oil path from the port P to the port B is opened between the oil paths 5b and 5c. When the other solenoid 7b is excited, the oil passage from the port P to the port A is opened and the oil passage from the port B to the port T is opened.

油圧ポンプ４と電磁式切換弁６との間の油路５ａに圧力制御弁としてのリリーフ弁１６が接続されている。リリーフ弁１６は、油圧ポンプ４から油路５ａに圧送される作動油が設定圧を超えたときに、作動油の一部を油路１７、１４を通じてオイルタンク３へドレンし、油圧シリンダー２に供給されるべき作動油の圧力を一定に保つ。   A relief valve 16 as a pressure control valve is connected to an oil passage 5 a between the hydraulic pump 4 and the electromagnetic switching valve 6. The relief valve 16 drains part of the hydraulic oil to the oil tank 3 through the oil passages 17 and 14 when the hydraulic oil pumped from the hydraulic pump 4 to the oil passage 5a exceeds the set pressure, The pressure of the hydraulic fluid to be supplied is kept constant.

パイロット操作型チェック弁１１の２次側ポート（油圧シリンダー２の側）に接続された油路５ｄに、オイルタンク３に接続された油路１４が接続されている。油路１４には、第３の絞り１８と、第３の絞り１８からオイルタンク３へドレンされる作動油の流通を開閉するための第２の切換弁１９と、が介在されている。第３の絞り１８は、スローリターン弁１２に内蔵されている第２の絞り１２ｂより小さい流路断面積を有している。第２の切換弁１９は、電磁式の２位置切換弁であり、非励磁時にはバネ１９ａによって油路１４を閉じるチェック弁の位置に付勢されており、ソレノイド１９ｂを励磁することによって油路１４を開通する位置に切り換えられる。   An oil passage 14 connected to the oil tank 3 is connected to an oil passage 5 d connected to the secondary port (the hydraulic cylinder 2 side) of the pilot operated check valve 11. A third throttle 18 and a second switching valve 19 for opening and closing the flow of hydraulic oil drained from the third throttle 18 to the oil tank 3 are interposed in the oil passage 14. The third throttle 18 has a smaller channel cross-sectional area than the second throttle 12b built in the slow return valve 12. The second switching valve 19 is an electromagnetic two-position switching valve, and is energized to the position of a check valve that closes the oil passage 14 by a spring 19a when not energized, and the oil passage 14 is energized by exciting the solenoid 19b. Can be switched to the position to open.

パイロット操作型チェック弁１１は、電磁式切換弁６のソレノイド６ａ及び第１の切換弁７のソレノイド７ｂが励磁されて油路５ｂからの作動油がパイロット圧作動油路１１ａを通じてパイロット圧として供給されると、内蔵するチェック弁を押し開いて、作動油の逆流を許容する。パイロット操作型チェック弁１１を逆流した作動油は、油路５ｃ、第１の切換弁７（ポートＢ，Ｔ）、油路２０、油路１４を通じてオイルタンク３にドレンされる。   In the pilot operated check valve 11, the solenoid 6a of the electromagnetic switching valve 6 and the solenoid 7b of the first switching valve 7 are excited, and hydraulic oil from the oil passage 5b is supplied as pilot pressure through the pilot pressure hydraulic oil passage 11a. Then, the built-in check valve is pushed open to allow backflow of hydraulic oil. The hydraulic fluid that has flowed back through the pilot operated check valve 11 is drained to the oil tank 3 through the oil passage 5 c, the first switching valve 7 (ports B and T), the oil passage 20, and the oil passage 14.

上記油圧回路は、油圧回路ブロックユニット２１に内蔵されている。図３は、上記油圧回路が内蔵された油圧回路ブロックユニット２１の要部を示す断面図である。   The hydraulic circuit is built in the hydraulic circuit block unit 21. FIG. 3 is a cross-sectional view showing a main part of the hydraulic circuit block unit 21 in which the hydraulic circuit is incorporated.

図３に示すように、抵抗弁１０は、油路８に段部で形成されたシート８ａに棒状の弁体１０ａがスプリング１０ｂによって押されて着座している。油路８の一次側に作動油が供給され、一次側圧力が設定圧を超えると弁体１０ａがシート８ａから離座し、作動油が油路８を通って油路５ｃに流れる。弁体１０ａは、シート８ａから離反すると、スプリング１０ｂのバネ力によってシート８ａからの離反距離が規制されている。   As shown in FIG. 3, the resistance valve 10 is seated on a seat 8 a formed in a step portion in the oil passage 8 by a rod-shaped valve body 10 a being pushed by a spring 10 b. When hydraulic oil is supplied to the primary side of the oil passage 8 and the primary pressure exceeds the set pressure, the valve body 10a is separated from the seat 8a, and the hydraulic oil flows through the oil passage 8 to the oil passage 5c. When the valve body 10a is separated from the seat 8a, the separation distance from the seat 8a is regulated by the spring force of the spring 10b.

図３を参照すれば、パイロット操作型チェック弁１１は、チェック弁本体１１ｂと、シート１１ｃと、チェック弁本体１１ｂをシート１１ｃに押圧するバネ１１ｄと、パイロットピストン１１ｅとを備えている。パイロットピストン１１ｅは、シート１１ｃを介してチェック弁本体１１ｂと対向配置されており、図３において左右に摺動自在に設置されている。パイロット圧作動油路１１ａに作動油が供給されると、パイロットピストン１１ｅは、図３の右側に押されて、ロッド部１１ｇがシート１１ｃの油路孔を通って、バネ１１ｄの押圧力に抗してチェック弁１１ｂを図３の右側に押して開弁させる。   Referring to FIG. 3, the pilot operated check valve 11 includes a check valve body 11b, a seat 11c, a spring 11d that presses the check valve body 11b against the seat 11c, and a pilot piston 11e. The pilot piston 11e is disposed so as to face the check valve main body 11b via the seat 11c, and is slidable in the left and right directions in FIG. When the hydraulic oil is supplied to the pilot pressure hydraulic oil passage 11a, the pilot piston 11e is pushed to the right in FIG. 3, and the rod portion 11g passes through the oil passage hole of the seat 11c and resists the pressing force of the spring 11d. Then, the check valve 11b is pushed to the right in FIG.

図外の油圧ポンプから油路５ｂに作動油が供給されると、油路８と油路１１ａとに供給される。抵抗弁１０は、油路８を通る作動油に抵抗を与えることにより、作動油の供給流量が少ない場合であっても、パイロット操作型チェック弁１１の開弁に必要なパイロット圧を確保し、パイロットピストン１１ｅがチェック弁本体１１ｂをシート１１ｃから離座させた後、抵抗弁１０の弁体１０ａがシート８ａから離座するように設計されている。   When hydraulic oil is supplied to the oil passage 5b from a hydraulic pump (not shown), it is supplied to the oil passage 8 and the oil passage 11a. The resistance valve 10 provides resistance to the hydraulic oil passing through the oil passage 8 to ensure a pilot pressure necessary for opening the pilot operated check valve 11 even when the hydraulic oil supply flow rate is small, The pilot piston 11e is designed so that the valve body 10a of the resistance valve 10 is separated from the seat 8a after the check valve body 11b is separated from the seat 11c.

上記構成を有する第１実施形態の油圧回路において、刈取部１を高速上昇させる場合は、電磁式切換弁６のソレノイド６ａを励磁させて油路５ａ、５ｂ間を開通させるとともに、第１の切換弁７のソレノイド７ａを励磁させて、油路５ｂ、５ｃ間のポートＰＢ間を開通させる。その結果、油圧ポンプ４から、油路５ａ、電磁式切換弁６、油路５ｂ、第１の切換弁７（ポートＰ，Ｂ）、油路５ｃ、パイロット操作型チェック弁１１、油路５ｄ、スローリターン弁１２、及び油路５ｅを通じて油圧シリンダー２に作動油が供給される。なお、このとき、作動油は、所定圧に達することにより抵抗弁１０を開いてバイパス油路８も通過するが、第１の絞り９によって流量が制限されているため、パイパス油路８を通過する作動油の流量は、第１の切換弁７を通過する作動油の流量より少ない。また、このとき、油路１１ａと油路２０を接続するポートＡＴ間も開通しており、図３を参照すれば、パイロットピストン１１ｅが油路５ｃを通る作動油によって図３の左側に押され、パイロットピストン１１ｅのパイロット圧作動油室１１ｆの作動油が油路１１ａ、油路２０を通じてドレンされる。   In the hydraulic circuit of the first embodiment having the above-described configuration, when the cutting unit 1 is raised at high speed, the solenoid 6a of the electromagnetic switching valve 6 is excited to open between the oil passages 5a and 5b, and the first switching is performed. The solenoid 7a of the valve 7 is excited to open between the ports PB between the oil passages 5b and 5c. As a result, from the hydraulic pump 4, the oil passage 5a, the electromagnetic switching valve 6, the oil passage 5b, the first switching valve 7 (ports P and B), the oil passage 5c, the pilot operated check valve 11, the oil passage 5d, Hydraulic oil is supplied to the hydraulic cylinder 2 through the slow return valve 12 and the oil passage 5e. At this time, when the hydraulic oil reaches a predetermined pressure, the resistance valve 10 is opened and the bypass oil passage 8 also passes. However, since the flow rate is restricted by the first throttle 9, the hydraulic oil passes through the bypass oil passage 8. The flow rate of the working oil is smaller than the flow rate of the working oil passing through the first switching valve 7. At this time, the port AT connecting the oil passage 11a and the oil passage 20 is also opened. Referring to FIG. 3, the pilot piston 11e is pushed to the left in FIG. 3 by the hydraulic oil passing through the oil passage 5c. The hydraulic oil in the pilot pressure hydraulic oil chamber 11f of the pilot piston 11e is drained through the oil passage 11a and the oil passage 20.

次に、刈取部１を低速上昇させる場合は、電磁式切換弁６のソレノイド６ａを励磁して油路５ａ、５ｂ間のポートを開通させておいて、第１の切換弁７を非励磁状態として中立位置とし、油路５ｂ、５ｃ間のポートＰＢ間を閉じる。その結果、油圧ポンプ４から、油路５ａ、電磁式切換弁６、油路５ｂ、バイパス油路８の第１の絞り９及び抵抗弁１０、油路５ｃ、パイロット操作型チェック弁１１、油路５ｄ、スローリターン弁１２、油路５ｅを通じて油圧シリンダー２に作動油が供給される。この場合、リリーフ弁１６からドレンされる量を除き、油圧ポンプ４からの作動油の全流量がバイパス油路８を介して第１の絞り９を通るので、油圧シリンダー２に供給される作動油の流量が第１の絞り９によって制限され、上記高速上昇の場合より刈取部１の上昇速度が低下する。   Next, when the mowing unit 1 is raised at a low speed, the solenoid 6a of the electromagnetic switching valve 6 is excited to open the port between the oil passages 5a and 5b, and the first switching valve 7 is not excited. As a neutral position, and the port PB between the oil passages 5b and 5c is closed. As a result, from the hydraulic pump 4, the oil passage 5a, the electromagnetic switching valve 6, the oil passage 5b, the first throttle 9 and the resistance valve 10 of the bypass oil passage 8, the oil passage 5c, the pilot operated check valve 11, the oil passage The hydraulic oil is supplied to the hydraulic cylinder 2 through 5d, the slow return valve 12, and the oil passage 5e. In this case, except for the amount drained from the relief valve 16, the entire flow rate of the hydraulic oil from the hydraulic pump 4 passes through the first throttle 9 via the bypass oil passage 8, so that the hydraulic oil supplied to the hydraulic cylinder 2 The flow rate is limited by the first throttle 9, and the ascending speed of the cutting unit 1 is reduced as compared with the case of the high speed increase.

刈取部１を高速下降させる場合は、電磁式切換弁６のソレノイド６ａを励磁して油路５ａ、５ｂ間を開通させる位置に切り換えておいて、第１の切換弁７のソレノイド７ｂを励磁させて、ポートＰＡ間を開通させて油路５ｂとパイロット圧作動油路１１ａと連通させ、且つ、ポートＢＴ間を開通させて油路５ｃと油路２０とを連通させてオイルタンク３にドレンする位置に切り換える。その結果、パイロット圧作動油路１１ａに供給された作動油が、油路２０を通じてパイロット圧として作用し、パイロット操作型チェック弁１１内のチェック弁本体１１ｂを開弁させ、作動油の逆流を許容する。このようにして、油圧シリンダー２のピストン室２ａ内の作動油が、油路５ｅ、スローリターン弁１２の第２の絞り１２ｂ、油路５ｄ、パイロット操作型チェック弁１１、油路５ｃを逆流し、第１の切換弁７（ポートＢ，Ｔ）から油路２０，１４を通じてオイルタンク３にドレンされる。オイルタンク３にドレンされる作動油は、第２の絞り１２ｂによってドレン流量が制限される。   When the mowing unit 1 is lowered at high speed, the solenoid 6a of the electromagnetic switching valve 6 is excited to switch to a position where the oil passages 5a and 5b are opened, and the solenoid 7b of the first switching valve 7 is excited. The port PA is opened to communicate with the oil passage 5b and the pilot pressure hydraulic fluid passage 11a, and the port BT is opened to connect the oil passage 5c and the oil passage 20 to be drained to the oil tank 3. Switch to position. As a result, the hydraulic oil supplied to the pilot pressure hydraulic oil passage 11a acts as a pilot pressure through the oil passage 20, opens the check valve body 11b in the pilot operated check valve 11, and allows backflow of the hydraulic oil. To do. In this way, the hydraulic oil in the piston chamber 2a of the hydraulic cylinder 2 flows back through the oil passage 5e, the second throttle 12b of the slow return valve 12, the oil passage 5d, the pilot operated check valve 11, and the oil passage 5c. Then, the oil is drained from the first switching valve 7 (ports B and T) to the oil tank 3 through the oil passages 20 and 14. The drain flow rate of the hydraulic oil drained to the oil tank 3 is limited by the second throttle 12b.

刈取部１を低速下降させる場合は、第２の切換弁１９のソレノイド１９ｂを励磁させ、油路１４を開通させる。その結果、油圧シリンダー２のピストン室２ａ内に蓄積された作動油は、油路５ｅ、スローリターン弁１２の第２の絞り１２ｂ、油路１４に介在された第３の絞り１８を通じて、オイルタンク３にドレンされる。第３の絞り１８は、第２の絞り１２ｂより流路断面積が小さいから、油路１４を流れる流量は、第３の絞り１８によって決定される。なお、電磁式切換弁６は中立位置にあり、このとき、油圧ポンプ４からの作動油は、油路１３ａ、１３ｂ、１４を通じてオイルタンク３にドレンされる。   When lowering the cutting part 1 at a low speed, the solenoid 19b of the second switching valve 19 is excited to open the oil passage 14. As a result, the hydraulic oil accumulated in the piston chamber 2 a of the hydraulic cylinder 2 passes through the oil passage 5 e, the second throttle 12 b of the slow return valve 12, and the third throttle 18 interposed in the oil passage 14, so that the oil tank 3 is drained. Since the third throttle 18 has a smaller channel cross-sectional area than the second throttle 12 b, the flow rate flowing through the oil passage 14 is determined by the third throttle 18. The electromagnetic switching valve 6 is in a neutral position, and at this time, the hydraulic oil from the hydraulic pump 4 is drained to the oil tank 3 through the oil passages 13a, 13b, and 14.

上記のように、刈取部１を低速上昇させる際には、第１の絞り９によって作動油の流量を制限することで、油圧シリンダー２のピストン移動速度を低下させている。従って、刈取部１の低速上昇時は、従来のブリードオフ回路とは異なり、メーターイン回路に切り換えて油圧シリンダー２を駆動することができるので、逃げ流量による変動が抑制され得る。なお、第１の絞り９によって作動油の流量が制限されても、第１の絞り９の一次側圧力はリリーフ弁１６によって圧力調整されているため、第１の絞り９を通過する作動油の流量の変動は防がれる。   As described above, when the mowing unit 1 is raised at a low speed, the piston moving speed of the hydraulic cylinder 2 is reduced by limiting the flow rate of the hydraulic oil by the first throttle 9. Therefore, when the mowing unit 1 rises at a low speed, unlike the conventional bleed-off circuit, the hydraulic cylinder 2 can be driven by switching to the meter-in circuit, so that fluctuation due to the escape flow rate can be suppressed. Even if the flow rate of the hydraulic oil is limited by the first throttle 9, the pressure on the primary side of the first throttle 9 is adjusted by the relief valve 16, so that the hydraulic oil that passes through the first throttle 9 is adjusted. Flow rate fluctuations are prevented.

油圧ポンプ４は、図示しないエンジンによって駆動しているため、例えばアイドリング時や湿田走行時等でエンジンが低速回転になると、油圧ポンプの吐出流量が低下する。エンジンが低速回転のとき、刈取部を低速上昇させようとしても、ブリードオフ回路では、油圧ポンプからの吐出流量が少ないため、逃げ流量を上回る流量が確保できず、低速上昇させることができないが、本発明では、エンジンが低速回転である場合、リリーフ弁１６から作動油の一部がドレンされても、作動油のリリーフ圧は確保されているため、低速上昇が可能である。   Since the hydraulic pump 4 is driven by an engine (not shown), the discharge flow rate of the hydraulic pump decreases when the engine rotates at a low speed, for example, when idling or during wetland driving. Even when trying to raise the mowing part at a low speed when the engine is rotating at a low speed, the bleed-off circuit has a small discharge flow rate from the hydraulic pump, so it cannot secure a flow rate that exceeds the escape flow rate, and cannot rise at a low speed. In the present invention, when the engine is rotating at a low speed, even if a part of the hydraulic oil is drained from the relief valve 16, the relief pressure of the hydraulic oil is secured, so that the low speed increase is possible.

また、供給油量制限用の第１の絞り９を、ドレン流量制限用の第２、第３の絞り１２ｂ、１８と別にしたので、コンバイン本機へのマッチングが容易となる。   In addition, since the first throttle 9 for limiting the amount of supply oil is separated from the second and third throttles 12b and 18 for limiting the drain flow rate, matching with the combine main unit is facilitated.

更に、上記のように刈取部１を高速下降させる場合、本発明の特徴部分である抵抗弁１０を備えない従来の油圧回路構成では、油圧ポンプ４から油路５ｂに供給された作動油が、油路８及び第１の絞り９、油路５ｃ、第１の切換弁７のポートＢＴ、油路２０、油路１４を通ってオイルタンク３にドレンされる経路が形成されるため、特にエンジンアイドリング時等の作動油投入流量が少ない場合に、パイロット操作型チェック弁１１を開弁するのにタイムラグが発生するが、本発明では、抵抗弁１０を設けたことにより、パイロット操作型チェック弁１１を開弁するのに必要なパイロット圧を直ちに発生させることができるので、タイムラグを減少させることができる。   Further, when the mowing unit 1 is lowered at a high speed as described above, in the conventional hydraulic circuit configuration that does not include the resistance valve 10 which is a characteristic part of the present invention, the hydraulic oil supplied from the hydraulic pump 4 to the oil passage 5b is Since a path for draining to the oil tank 3 through the oil path 8, the first throttle 9, the oil path 5c, the port BT of the first switching valve 7, the oil path 20, and the oil path 14 is formed, particularly the engine. When the flow rate of hydraulic fluid input at idling or the like is small, a time lag occurs when the pilot operated check valve 11 is opened. However, in the present invention, by providing the resistance valve 10, the pilot operated check valve 11 is provided. Since the pilot pressure required to open the valve can be generated immediately, the time lag can be reduced.

なお、本発明は、上記実施形態に限らず、本発明の技術的思想を逸脱しない範囲において種々の変更が可能である。   The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the technical idea of the present invention.

例えば、図４に示すように、上記第１実施形態のスローリターン弁１２に代えて、油路２０に第２の絞り１２ｂを設けることもできるし、さらに、図５に示すように、油路２０の第２の絞り１２ｂのドレンタンク３側に第２の切換弁１９Ａを設け、第２の切換弁１９Ａと並列に第３の絞り１８を接続する回路構成とすることもできる。   For example, as shown in FIG. 4, instead of the slow return valve 12 of the first embodiment, a second throttle 12b can be provided in the oil passage 20, and further, as shown in FIG. A circuit configuration is also possible in which a second switching valve 19A is provided on the drain tank 3 side of the 20 second throttle 12b, and the third throttle 18 is connected in parallel with the second switching valve 19A.

１ 刈取部
２ 油圧シリンダー
３ オイルタンク
４ 油圧ポンプ
７ 第１の切換弁
９ 第１の絞り
１０ 抵抗弁
１１ パイロット操作型チェック弁
１２ｂ 第２の絞り
１８ 第３の絞り
１９、１９Ａ 第２の切換弁 DESCRIPTION OF SYMBOLS 1 Cutting part 2 Hydraulic cylinder 3 Oil tank 4 Hydraulic pump 7 1st switching valve 9 1st throttle 10 Resistance valve 11 Pilot operation type check valve 12b 2nd throttle 18 3rd throttle 19, 19A 2nd switching valve

Claims (2)

コンバインの刈取部を昇降させる油圧シリンダーを、オイルタンクから油圧ポンプを介して送られる作動油によって駆動するための油圧回路であって、
パイロット圧を利用して前記油圧シリンダーから作動油の逆流を許容するパイロット操作型チェック弁と、
給圧一次側ポートと油圧シリンダー作動油路用二次側ポートとを開通させる第１の位置と、前記給圧一次側ポートとパイロット圧作動油路用二次側ポートとを開通させるとともに前記油圧シリンダー作動油路用二次側ポートとタンクポートとを開通させる第２の位置と、前記給圧一次側ポートおよび前記油圧シリンダー作動油路用二次側ポートを閉じる第３の位置と、に切り換え可能な第１の切換弁と、
前記第１の切換弁と並列に接続され、前記油圧ポンプから前記油圧シリンダーへ供給される作動油の流量を制限するための第１の絞りと、
前記第１の絞りと直列に接続され、前記第１の切換弁が前記第２の位置にあるときに、前記第１の絞りを通る作動油を規制して前記パイロット操作型チェック弁のパイロット圧を確保するための抵抗弁と、
前記パイロット操作型チェック弁を逆流してドレンされる作動油の流量を制限するための第２の絞りと、
前記第２の絞りより小さい流路断面積を備え、ドレンされる作動油の流量を制限するための第３の絞りと、
ドレンされる作動油の油路を、前記第３の絞りを通じてドレンされる作動油の油路に選択的に切換可能な第２の切換弁と、
を備え、
前記抵抗弁の設定圧は、前記パイロット操作型チェック弁のパイロット圧よりも大きい、油圧回路。 A hydraulic circuit for driving a hydraulic cylinder that raises and lowers a harvesting portion of a combine with hydraulic oil sent from an oil tank via a hydraulic pump,
A pilot operated check valve that allows the backflow of hydraulic oil from the hydraulic cylinder using pilot pressure; and
A first position for opening the supply pressure primary side port and the hydraulic cylinder hydraulic fluid passage secondary port, and opening the supply pressure primary port and the pilot pressure hydraulic passage secondary port and the hydraulic pressure Switching between the second position for opening the secondary port for the cylinder hydraulic fluid passage and the tank port and the third position for closing the secondary port for the hydraulic pressure hydraulic hydraulic fluid passage and the secondary port for the hydraulic cylinder hydraulic fluid passage A possible first switching valve;
A first throttle connected in parallel with the first switching valve for limiting a flow rate of hydraulic oil supplied from the hydraulic pump to the hydraulic cylinder;
When connected in series with the first throttle and the first switching valve is in the second position, the hydraulic oil passing through the first throttle is regulated to control the pilot pressure of the pilot operated check valve. A resistance valve to ensure,
A second throttle for limiting the flow rate of the drained hydraulic fluid by flowing back through the pilot operated check valve;
A third throttle for limiting the flow rate of the drained hydraulic oil, having a smaller channel cross-sectional area than the second throttle;
A second switching valve capable of selectively switching a drained hydraulic oil passage to a drained hydraulic fluid passage through the third throttle;
With
A hydraulic circuit in which a set pressure of the resistance valve is larger than a pilot pressure of the pilot operated check valve . 前記パイロット操作型チェック弁は、チェック弁本体と、該チェック弁本体が離座可能なシートと、前記チェック弁本体を前記シートに押圧付勢するバネと、前記チェック弁本体と前記シートを介して対向して摺動自在に配置されたパイロットピストンと、を備えることを特徴とする請求項１に記載の油圧回路。
The pilot operated check valve includes a check valve body, a seat from which the check valve body can be separated, a spring that presses and urges the check valve body against the seat, and the check valve body and the seat. The hydraulic circuit according to claim 1, further comprising a pilot piston that is slidably disposed opposite to the pilot circuit.
JP2012145655A 2012-06-28 2012-06-28 Hydraulic circuit for lifting the harvesting part of the combine Active JP5957735B2 (en)

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JP2012145655A JP5957735B2 (en) 2012-06-28 2012-06-28 Hydraulic circuit for lifting the harvesting part of the combine
CN201310203741.5A CN103511370B (en) 2012-06-28 2013-04-24 The harvesting portion lifting hydraulic circuit of united reaper
KR1020130047540A KR101755064B1 (en) 2012-06-28 2013-04-29 Hydraulic circuit for lifting and lowering reaping part of combine harvester
TW102118239A TWI583298B (en) 2012-06-28 2013-05-23 Hydraulic circuit for lifting and lowering reaping part of combine harvester

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