JPH03282061A - Hydraulic circuit for closed circuit hydraulic transmission - Google Patents

Abstract

PURPOSE:To reduce the weight and cost of a device by mounting a safety valve on a connection part between high pressure circuits on both sides, and relieving high pressure oil of each main circuit by means of the same safety valve. CONSTITUTION:Even when one of left first and second main circuits 3 and 4, whichever it may be, is brought into a high pressure state, high pressure oil is caused to flow to a left high pressure circuit 22 by means of a left shuttle valve 24. Even when one of right first and second main circuits 7 and 8, whichever it may be, is brought into a high pressure state, high pressure oil is caused to flow to a right high pressure circuit 27 by means of a right shuttle valve 29. High pressure oil of left and right high pressure circuits 22 and 27 flows through a check valve 31 to the high pressure side of a safety valve 36, and when the pressure thereof is increased to a value higher than a set value, the safety valve 36 performs relief operation and the high pressure oil flows to the low pressure side. In this case, since a neutral bypass valve 35 is brought into a shut-off position (d), no influence is exercised on relief operation of the safety valve 36. Since the maximum pressures of the main circuits can be made equal to each other and mounting of one safety valve suffices for operation of a hydraulic circuit, the weight of a device is reduced and a device cost is decreased.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、可変容量型油圧ポンプと油圧モータを閉回路
接続した油圧トランスミッションを左右一対備えた油圧
駆動車両における閉回路油圧トランスミッションの油圧
回路、特に、可変容量型油圧ポンプと油圧モータを接続
する主回路の高圧油をリリーフする安全弁に関する。[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a hydraulic circuit of a closed circuit hydraulic transmission in a hydraulically driven vehicle equipped with a pair of left and right hydraulic transmissions in which a variable displacement hydraulic pump and a hydraulic motor are connected in a closed circuit; In particular, the present invention relates to a safety valve that relieves high-pressure oil in a main circuit connecting a variable displacement hydraulic pump and a hydraulic motor.

〔従来の技術〕[Conventional technology]

特開昭５８−１２８５５８号公報に示す閉回路油圧トラ
ンスミッションの油圧回路が知られている。A hydraulic circuit for a closed circuit hydraulic transmission disclosed in Japanese Patent Application Laid-open No. 58-128558 is known.

つまり、可変容量型油圧ポンプと油圧モータを第１、第
２主回路で閉回路接続した油圧トランスミッションを左
右一対設け、左右の油圧トランスミッションの可変容量
型油圧ポンプの容量、吐出方向を制御して左右の油圧ト
ランスミッションの回転速度、回転速度を異ならせるこ
とで前進、後進、左右旋回走行する油圧回路である。In other words, a pair of left and right hydraulic transmissions are provided, in which a variable displacement hydraulic pump and a hydraulic motor are connected in a closed circuit through first and second main circuits, and the capacity and discharge direction of the variable displacement hydraulic pumps of the left and right hydraulic transmissions are controlled. This is a hydraulic circuit that allows the vehicle to travel forward, backward, and turn left and right by varying the rotational speed of the hydraulic transmission.

〔発明が解決しようとする課題〕[Problem to be solved by the invention]

かかる油圧回路においては可変容量型油圧ポンプの吐出
方向が第１主回路と第２主回路に切換わるので、第１主
回路と第２主回路が高圧となり、第１主回路の高圧油を
リリーフする安全弁と第２主回路の高圧油をリリーフす
る安全弁を必要とし、しかも油圧トランスミッションを
左右一対備えているので、結局４つの安全弁が必要とな
る。In such a hydraulic circuit, the discharge direction of the variable displacement hydraulic pump is switched between the first main circuit and the second main circuit, so the first main circuit and the second main circuit become high pressure, and the high pressure oil in the first main circuit is relieved. A safety valve for relieving high-pressure oil in the second main circuit is required, and since a pair of hydraulic transmissions are provided on the left and right sides, four safety valves are required in the end.

このために、各安全弁のリリーフセット圧の設定バラツ
キが生じ、それによって主回路内の最高圧が不揃いとな
ってしまうばかりか、機器ｆｆｌ大でコスト高となる。For this reason, the settings of the relief set pressures of the respective safety valves vary, which not only causes the maximum pressure in the main circuit to be uneven, but also increases the equipment ffl and increases costs.

そこで、本発明は前述の課題を解決できるようにした閉
回路油圧トランスミッションの油圧回路を提供すること
を目的とする。SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a hydraulic circuit for a closed-circuit hydraulic transmission that can solve the above-mentioned problems.

〔課題を解決するための手段及び作用〕左油圧トランス
ミッションの左第１、第２主回路の高圧油を左高圧回路
に導入する左シャトル弁と、右油圧トランスミッション
の右第１、第２主回路の高圧油を右高圧回路に導入する
右シャトル弁と、前記左右高圧回路の接続部に接続した
安全弁を設け、各主回路の高圧油を同一の安全弁でリリ
ーフできるようにしたものである。[Means and effects for solving the problem] A left shuttle valve that introduces high pressure oil from the left first and second main circuits of the left hydraulic transmission into the left high pressure circuit, and a right first and second main circuit of the right hydraulic transmission. A right shuttle valve that introduces the high-pressure oil into the right high-pressure circuit, and a safety valve connected to the connection part of the left and right high-pressure circuits are provided, so that the high-pressure oil in each main circuit can be relieved by the same safety valve.

〔実　施　例〕〔Example〕

以下本発明の実施例を図面を参照して説明する。 Embodiments of the present invention will be described below with reference to the drawings.

（全体の概略） 第１図に示すように、左油圧トランスミッションＡと右
油圧トランスミッションＢと操向操作部Ｃとより閉回路
油圧トランスミッションを構成し、操向操作部Ｃを操作
することで左右油圧トランスミッションＡ、Ｂの回転速
度、回転方向を制御することで左スプロケットＤと右ス
プロケットＥを回転して直進、旋回走行するようにしで
ある。(Overall outline) As shown in Fig. 1, a left hydraulic transmission A, a right hydraulic transmission B, and a steering operation part C constitute a closed circuit hydraulic transmission, and by operating the steering operation part C, the left and right hydraulic By controlling the rotational speed and direction of transmissions A and B, the left sprocket D and right sprocket E are rotated to allow the vehicle to travel straight and turn.

前記左油圧トランスミッションＡは左可変容量型油圧ポ
ンプ１（以下左油圧ポンプ１という）と左油圧モータ２
を左第１、第２主回路３．４で閉回路接続して成り、右
油圧トランスミッションＢは右可変容量型油圧ポンプ５
（以下右油圧ポンプ５という）と右油圧モータ６を右第
１・第２主回路７．８で閉回路接続しである。The left hydraulic transmission A includes a left variable displacement hydraulic pump 1 (hereinafter referred to as left hydraulic pump 1) and a left hydraulic motor 2.
are connected in a closed circuit by the left first and second main circuits 3.4, and the right hydraulic transmission B is connected to the right variable displacement hydraulic pump 5.
(hereinafter referred to as the right hydraulic pump 5) and the right hydraulic motor 6 are connected in a closed circuit through the right first and second main circuits 7.8.

前記左右油圧ポンプ１，５は斜板１ａ、５ａの角度を変
更することで容量、つまり１回転当り吐出量を可変とす
る斜板式の可変容量型油圧ポンプとなり、その斜板１ａ
、５ａは左右サーボシリンダ９．１０で傾動され、左右
サーボシリンダ９，１０には左右制御弁１１．１２によ
って補助油圧ポンプ１３の吐出圧油が供給される。The left and right hydraulic pumps 1, 5 are variable displacement hydraulic pumps of the swash plate type that can vary the capacity, that is, the discharge amount per revolution by changing the angles of the swash plates 1a, 5a.
, 5a are tilted by left and right servo cylinders 9.10, and the left and right servo cylinders 9, 10 are supplied with discharge pressure oil from the auxiliary hydraulic pump 13 by left and right control valves 11.12.

前記操向操作部Ｃは油圧パイロット弁１４となり、その
油圧パイロット弁１４は１本のレバー１５を前後に揺動
することで第１・第２減圧弁１６．１７を作動し、レバ
ー１５を左右に揺動すると第３、第４減圧弁１８．１９
を作動する構成であり、各減圧弁は前記補助油圧ポンプ
１３の吐出圧油をレバー１５の操作ストロークに比例し
て出力する構成である。The steering operation section C becomes a hydraulic pilot valve 14, and the hydraulic pilot valve 14 operates the first and second pressure reducing valves 16 and 17 by swinging one lever 15 back and forth, and the lever 15 is moved left and right. When it swings, the third and fourth pressure reducing valves 18.19
Each pressure reducing valve is configured to output pressure oil discharged from the auxiliary hydraulic pump 13 in proportion to the operation stroke of the lever 15.

次に各部の詳細を説明する。Next, details of each part will be explained.

前記左第１・第２主回路３．４には一対のチェック弁２
０．２０を介して左チャージ回路２１が接続し、左高圧
回路２２と左低圧回路２３が左シャトル弁２４で高圧側
主回路、低圧側主回路に接続されて左第１・第２主回路
３．４における高圧油を左高圧回路２２に、低圧油を左
低圧回路２３にそれぞれ導入できるようにしである。A pair of check valves 2 are installed in the left first and second main circuits 3.4.
0.20, the left charge circuit 21 is connected, and the left high pressure circuit 22 and left low pressure circuit 23 are connected to the high pressure side main circuit and the low pressure side main circuit by the left shuttle valve 24, and the left first and second main circuits are connected. 3.4, the high pressure oil can be introduced into the left high pressure circuit 22, and the low pressure oil can be introduced into the left low pressure circuit 23.

前記右第１・第２主回路７，８には一対のチェック弁２
５．２５を介して右チャージ回路２６が接続し、右高圧
回路２７と右低圧回路２８が右シャトル弁２９で高圧側
主回路、低圧側主回路に接続されて右第１・第２主回路
７，８における高圧油を右高圧回路２７に、低圧油を右
低圧回路２８にそれぞれ導入できるようにしである。A pair of check valves 2 are provided in the right first and second main circuits 7 and 8.
5.25, the right charge circuit 26 is connected, and the right high pressure circuit 27 and right low pressure circuit 28 are connected to the high pressure side main circuit and the low pressure side main circuit by the right shuttle valve 29, and the right first and second main circuits are connected. The high-pressure oil at 7 and 8 can be introduced into the right high-pressure circuit 27, and the low-pressure oil can be introduced into the right low-pressure circuit 28, respectively.

前記左チャージ回路２１と右チャージ回路２６は前記補
助油圧ポンプ１３の吐出路１３ａに接続し、かつ安全弁
３０が設けである。The left charge circuit 21 and the right charge circuit 26 are connected to the discharge passage 13a of the auxiliary hydraulic pump 13, and are provided with a safety valve 30.

前記左高圧回路２２と右高圧回路２７は一対のチェック
弁３１．３１を介して接続し、さらに左高圧回路２２と
右高圧回路２７における前記一対のチェック弁３１．３
１の入口側がイコライズ弁３２を介して連通している。The left high pressure circuit 22 and the right high pressure circuit 27 are connected via a pair of check valves 31.31, and the pair of check valves 31.3 in the left high pressure circuit 22 and the right high pressure circuit 27 are connected to each other via a pair of check valves 31.31.
The inlet side of the valve 1 is connected to the valve 1 through an equalization valve 32.

該イコライズ弁３２は左右高圧回路２２．２７の左右高
圧油の圧力差がない時には絞り３２ａを有する連通位置
ａに保持され、圧力差がある時には遮断位置すに切換わ
る構成となっている。The equalizing valve 32 is held at the communicating position a with the throttle 32a when there is no pressure difference between the left and right high pressure oils in the left and right high pressure circuits 22, 27, and is switched to the blocking position when there is a pressure difference.

前記左低圧回路２３と右低圧回路２８は接続し、かつ低
圧リリーフ弁３３、オイルクーラ３４を経て前記左右油
圧モータ２，６の冷却回路２ａ。The left low pressure circuit 23 and the right low pressure circuit 28 are connected, and the cooling circuit 2a for the left and right hydraulic motors 2 and 6 is connected via a low pressure relief valve 33 and an oil cooler 34.

６ａに接続している。Connected to 6a.

前記左右高圧回路２２．２７における一対のチェック弁
３１．３１間は中立バイパス弁３５で前記左右チェージ
回路２１，２６、つまり補助油圧ポンプ１３の吐出路１
３ａに接続し、かつ安全弁３６で前記低圧リリーフ弁３
３の入口側に接続している。A neutral bypass valve 35 is provided between the pair of check valves 31 and 31 in the left and right high pressure circuits 22 and 27 to connect the left and right check circuits 21 and 26, that is, the discharge path 1 of the auxiliary hydraulic pump 13.
3a, and the safety valve 36 connects the low pressure relief valve 3
It is connected to the entrance side of 3.

前記中立バイパス弁３５はバネ力３５ａで連通位置Ｃに
保持され、受圧部３５ｂのパイロット圧油で遮断位置ｄ
に切換わる構成である。The neutral bypass valve 35 is held in the communicating position C by a spring force 35a, and is held in the blocking position d by pilot pressure oil in the pressure receiving part 35b.
This configuration switches to

前記安全弁３０の低圧側は左右油圧ポンプ１゜５の冷却
回路１ｂ、５ｂに接続している。The low pressure side of the safety valve 30 is connected to the cooling circuits 1b and 5b of the left and right hydraulic pumps 1.5.

前記左右制御弁１１．１２はバネ力でドレーン位置ｅに
保持され、第１・第２受圧部１１ａ。The left and right control valves 11.12 are held at the drain position e by spring force, and the first and second pressure receiving portions 11a.

１１ｂ、１２ａ、１２ｂと第３、第４受圧部１１ｃ、ｌ
ｉｄ、１２ｃ、１２ｄのパイロット圧油の圧力差で前進
位置ｆ１後進位置ｇに切換えられる構成となり、左右制
御弁１１．１２が前進位置ｆとなると前記補助油圧ポン
プ１３の吐出圧油が左右サーボシリンダ９．１０の第１
室９ａ、１０ａに供給されて左右油圧モータ１゜５の斜
板１ａ、５ａが前進側に傾動して左右第１主回路３，７
に圧油を吐出し、左右油圧モータ２．６が正転して車両
は前進し、左右制御弁１１．１２が後進位Ｋｇとなると
補助油圧ポンプ１３の吐出圧油が左右サーボシリンダ９
゜１０の第２室９ｂ、１０ｂに供給されて左右油圧モー
タ１．５の斜板１ａ、５ｂが後進側に傾動して左右第２
主回路４．８に圧油を吐出し、左右油圧モータ２，６が
逆転して車両は後進する。11b, 12a, 12b and third and fourth pressure receiving parts 11c, l
The configuration is such that the pressure difference between the pilot pressure oils id, 12c, and 12d switches the forward position f1 to the reverse position g, and when the left and right control valves 11.12 reach the forward position f, the pressure oil discharged from the auxiliary hydraulic pump 13 is transferred to the left and right servo cylinders. 9.10 1st
Supplied to the chambers 9a, 10a, the swash plates 1a, 5a of the left and right hydraulic motors 1.5 tilt toward the forward side, causing the left and right first main circuits 3, 7 to move forward.
When the left and right hydraulic motors 2.6 rotate forward and the vehicle moves forward, and the left and right control valves 11.12 reach the reverse position Kg, the pressure oil discharged from the auxiliary hydraulic pump 13 is transferred to the left and right servo cylinders 9.
The swash plates 1a, 5b of the left and right hydraulic motors 1.5 are supplied to the second chambers 9b, 10b of
Pressure oil is discharged to the main circuit 4.8, and the left and right hydraulic motors 2, 6 are reversed, causing the vehicle to move backward.

前記油圧パイロット弁１４の各減圧弁の入口ボート４０
は第１切換弁４１、手動開閉弁４２を介して前記補助油
圧ポンプ１３の吐出路１３ａに接続し、その入口ボート
４０はレバー１５を操作しない時には遮断され、レバー
１５を操作することで出口ポート４３に連通され、第１
減圧弁１６の出口ボート４３に第１パイロツト路４４が
接続され、第２、第３、第４減圧弁１７゜１８．１９の
出口ボート４３に第２、第３、第４パイロット路４５．
４６．４７がそれぞれ接続しである。Inlet boat 40 of each pressure reducing valve of the hydraulic pilot valve 14
is connected to the discharge passage 13a of the auxiliary hydraulic pump 13 via a first switching valve 41 and a manual on-off valve 42, and its inlet port 40 is shut off when the lever 15 is not operated, and the outlet port is opened by operating the lever 15. 43, the first
A first pilot passage 44 is connected to the outlet boat 43 of the pressure reducing valve 16, and second, third and fourth pilot passages 45.
46 and 47 are connected respectively.

なお、第１・第２減圧弁１６．１７のタンクボート４８
は絞り４９を経てタンク側に接続している。In addition, the tank boat 48 of the first and second pressure reducing valves 16 and 17
is connected to the tank side through a throttle 49.

前記第１パイロツト路４４は左制御弁１１の第１受圧部
１１ａと右制御弁１２の第１受圧部１２ａに接続し、第
２パイロツト路４５は左制御弁１１の第３受圧部１１ｃ
と右制御弁１２の第３受圧部１２ｃに接続し、第３パイ
ロツト路４６は左制御弁１１の第２、第４受圧部１１ｂ
。The first pilot passage 44 is connected to the first pressure receiving part 11a of the left control valve 11 and the first pressure receiving part 12a of the right control valve 12, and the second pilot passage 45 is connected to the third pressure receiving part 11c of the left control valve 11.
and the third pressure receiving portion 12c of the right control valve 12, and the third pilot path 46 connects to the second and fourth pressure receiving portions 11b of the left control valve 11.
.

１１ｄに接続し、第４パイロツト路４７は右制御弁１２
の第２、第４受圧部１２ｂ、１２ｄに接続している。11d, and the fourth pilot passage 47 is connected to the right control valve 12.
It is connected to the second and fourth pressure receiving parts 12b and 12d.

これにより、レバー１５を前側に揺動して第１減圧弁１
６を作動すると第１パイロツト路４４から左右制御弁１
１．１２の第１受圧部１１ａ。As a result, the lever 15 is swung forward and the first pressure reducing valve 1 is opened.
6, the left and right control valves 1 are operated from the first pilot passage 44.
1.12 first pressure receiving part 11a.

１２ａにパイロット圧油が供給されて左右制御弁１１．
１２が前進位置ｆとなるので、前述のように車両は前進
する。Pilot pressure oil is supplied to the left and right control valves 11.12a.
12 is the forward position f, so the vehicle moves forward as described above.

レバー１５を後側に揺動して第２減圧弁１７を作動する
と第２パイロツト路４５から左右制御弁１１．１２の第
３受圧部１１ｃ、１２ｃにパイロット圧油が供給されて
左右制御弁１１゜１２が後進位置ｇとなるので、前述の
ように車両は後進する。When the lever 15 is swung rearward to operate the second pressure reducing valve 17, pilot pressure oil is supplied from the second pilot passage 45 to the third pressure receiving portions 11c and 12c of the left and right control valves 11.12. Since °12 is the reverse position g, the vehicle travels backward as described above.

レバー１５を前方に揺動して各第１受圧部１１ａ、１２
ａにパイロット圧油を供給して左右制御弁１１．１２を
前進位置ｆとして前進走行している状態で、レバー１５
を斜め左側に揺動して第３減圧弁１８を作動すると、第
３パイロツト路４６にもパイロット圧油が供給されて左
制御弁１１の第２、第４受圧部１１ｂ、ｌｉｄにもパイ
ロット圧油がそれぞれ供給され、左制御弁１１の第２受
圧部１１ｂの圧油による前進位置ｆへの力が第１受圧部
１１ａの圧油によって打ち消されると共に、第４受圧部
ｌｉｄの圧油により中立位置ｅへの力が作用するから左
制御弁１１の切換えストロークが右制御弁１２の切換え
ストロークより短かくなって左油圧ポンプ１の斜板角度
が右油圧ポンプ５の斜板角度より小さくなって容量が少
なくなり、左油圧トランスミッションＡの回転速度が右
油圧トランスミッションＢの回転速度より遅くなるので
、車両は前進左旋回走行する。By swinging the lever 15 forward, each first pressure receiving part 11a, 12
While driving forward with pilot pressure oil supplied to a and the left and right control valves 11 and 12 set to the forward position f, the lever 15
When the third pressure reducing valve 18 is actuated by swinging diagonally to the left, pilot pressure oil is also supplied to the third pilot passage 46, and pilot pressure is also applied to the second and fourth pressure receiving parts 11b and lid of the left control valve 11. Oil is supplied to each of the left control valves 11, and the force toward the forward position f due to the pressure oil in the second pressure receiving part 11b of the left control valve 11 is canceled by the pressure oil in the first pressure receiving part 11a, and the pressure oil in the fourth pressure receiving part lid moves the left control valve 11 to the neutral position. Since the force toward position e is applied, the switching stroke of the left control valve 11 becomes shorter than the switching stroke of the right control valve 12, and the swash plate angle of the left hydraulic pump 1 becomes smaller than the swash plate angle of the right hydraulic pump 5. Since the capacity is reduced and the rotational speed of the left hydraulic transmission A becomes slower than the rotational speed of the right hydraulic transmission B, the vehicle moves forward and turns left.

レバー１５を後方に揺動している状態で、レバー１５を
斜め左側に揺動して第３減圧弁１８を作動すると前述と
同様に左制御弁１１の切換えストロークが右制御弁１２
の切換えストロークより短かくなって左油圧ポンプ１の
容量が右油圧ポンプ５の容量より少なくなるので、車両
は後進左旋回走行する。When the lever 15 is swung backward and the third pressure reducing valve 18 is actuated by swiveling the lever 15 diagonally to the left, the switching stroke of the left control valve 11 changes to the right control valve 12 as described above.
Since the switching stroke is shorter than the switching stroke, the capacity of the left hydraulic pump 1 becomes smaller than the capacity of the right hydraulic pump 5, and the vehicle moves backward and turns to the left.

レバー１５を前方に揺動している状態で、レバー１５を
斜め右側に揺動して第４減圧弁１９を作動すると、第４
パイロツト路４７にもパイロット圧油が供給され、右制
御弁１２の第２、第４受圧部１２ｂ、］２ｄにもパイロ
ット圧油が供給されるので、前述と同様に右制御弁１２
の切換えストロークが左制御弁１１の切換えストローク
より短かくなって右油圧ポンプ５の斜板角度が左油圧ポ
ンプ１の斜板角度より小さくなり、右油圧ポンプ５の容
量が左油圧ポンプ５の容量より少なくなって、右油圧ト
ランスミッションＢの回転速度が左油圧トランスミッシ
ョンＡの回転速度より遅くなり、車両は前進右旋回走行
する。When the lever 15 is swung forward and the fourth pressure reducing valve 19 is actuated by swiveling the lever 15 diagonally to the right, the fourth pressure reducing valve 19 is activated.
Pilot pressure oil is also supplied to the pilot passage 47, and pilot pressure oil is also supplied to the second and fourth pressure receiving parts 12b, ]2d of the right control valve 12, so that the right control valve 12
The switching stroke of the left control valve 11 becomes shorter than that of the left hydraulic pump 11, the swash plate angle of the right hydraulic pump 5 becomes smaller than the swash plate angle of the left hydraulic pump 1, and the capacity of the right hydraulic pump 5 becomes the capacity of the left hydraulic pump 5. As a result, the rotational speed of the right hydraulic transmission B becomes slower than the rotational speed of the left hydraulic transmission A, and the vehicle moves forward and turns to the right.

レバー１５を後方に揺動している状態で、レバー１５を
斜め右側に揺動して第４減圧弁１９を作動すると、第４
パイロツト路４７にもパイロット圧油が供給されて前述
と同様に右制御弁１２の切換えストロークが左制御弁１
１の切換えストロークより短かくなって右油圧ポンプ５
の容量が左油圧ポンプ１の容量より少なくなり、車両は
後進右旋回走行する。When the lever 15 is swung diagonally to the right while the lever 15 is swung backwards to operate the fourth pressure reducing valve 19, the fourth pressure reducing valve 19 is activated.
Pilot pressure oil is also supplied to the pilot passage 47, and the switching stroke of the right control valve 12 is changed to the left control valve 1 in the same manner as described above.
The right hydraulic pump 5 is shorter than the switching stroke of 1.
The capacity of the left hydraulic pump 1 becomes smaller than that of the left hydraulic pump 1, and the vehicle moves backward and turns to the right.

前記第１切換弁４１は連通位置ｉに保持され、操作部材
、例えばインチング・ブレーキペダルで遮断位置ｊに向
けて操作され、第１切換弁４１を遮断位置Ｊとすると油
圧パイロット弁１４の各減圧弁の入口ポート４０がドレ
ーンに連通し、左右制御弁１１．１２の各受圧部がドレ
ーンに連通されて左右制御弁１１．１２はドレーン位置
ｅとなり、左右油圧モータ１，５の斜板１ａ。The first switching valve 41 is held at the communication position i and operated toward the cutoff position j by an operating member, such as an inching brake pedal. The inlet port 40 of the valve communicates with the drain, and each pressure receiving part of the left and right control valves 11.12 communicates with the drain, so that the left and right control valves 11.12 are in the drain position e, and the swash plate 1a of the left and right hydraulic motors 1 and 5.

５ａは最小角度位置となって最小容量となる。5a is the minimum angular position and has the minimum capacity.

前記第１、第２パイロット路４４．４５はシャトル弁５
０で圧力検出回路５１に接続し、その圧力検出回路５１
は前記中立バイパス弁３５の受圧部３５ｂに接続し、レ
バー１５を前後に揺動して前述のように車両を走行する
時には第１パイロツト路４４又は第２パイロツト路４５
のパイロット圧油がシャトル弁５０で圧力検出回路５１
に検出され、その圧油が中立バイパス弁３５の受圧部３
５ｂに供給されて遮断位置ｄとする。The first and second pilot paths 44 and 45 are connected to the shuttle valve 5.
0 to connect to the pressure detection circuit 51, and the pressure detection circuit 51
is connected to the pressure receiving part 35b of the neutral bypass valve 35, and when the lever 15 is swung back and forth to drive the vehicle as described above, the lever 15 is connected to the first pilot path 44 or the second pilot path 45.
The pilot pressure oil is detected by the shuttle valve 50 and the pressure detection circuit 51.
The pressure oil is detected in the pressure receiving part 3 of the neutral bypass valve 35.
5b to set the cutoff position d.

前記左右スプロケットＤ、Ｅは駐車ブレーキ６０を備え
、その駐車ブレーキ６０をブレーキ板６１とブレーキシ
リンダ６２より成り、ブレーキシリンダ６２をバネ６３
で伸長付勢して制動状態とし、縮少室６４に圧油を供給
することでブレーキシリンダ６２を縮少すると解除状態
となり、その縮少室６４はブレーキ回路６５に接続して
いる。The left and right sprockets D and E are equipped with a parking brake 60, which consists of a brake plate 61 and a brake cylinder 62, and the brake cylinder 62 is connected to a spring 63.
When the brake cylinder 62 is compressed by supplying pressurized oil to the contraction chamber 64 and the brake cylinder 62 is compressed, the brake cylinder 62 is brought into a released state, and the contraction chamber 64 is connected to a brake circuit 65 .

該ブレーキ回路６５は第２切換弁６６で前記補助油圧ポ
ンプ１３の吐出路１３ａにおける手動開閉弁４２と第１
切換弁４１との間に接続してあり、その第２切換弁６６
はバネ力でドレーン位置ｋに保持され、受圧部６６ａの
パイロット圧油で連通位置Ωとなる構成で、その受圧部
６６ａは前記圧力検出回路５１に接続されて、前述のよ
うに車両を走行する時には第２切換弁６６の受圧部６６
ａにパイロット圧油が供給されて連通位置ｇとなり、補
助油圧ポンプ１３の吐出圧油がブレーキ回路６５に供給
されて駐車ブレーキ６０が解放される。The brake circuit 65 has a second switching valve 66 that connects the manual on-off valve 42 and the first switching valve in the discharge passage 13a of the auxiliary hydraulic pump 13.
The second switching valve 66 is connected between the switching valve 41 and the switching valve 41 .
is held at the drain position k by a spring force, and brought to the communication position Ω by pilot pressure oil in the pressure receiving part 66a, and the pressure receiving part 66a is connected to the pressure detection circuit 51, and the vehicle runs as described above. Sometimes the pressure receiving part 66 of the second switching valve 66
Pilot pressure oil is supplied to a to set the communication position g, and pressure oil discharged from the auxiliary hydraulic pump 13 is supplied to the brake circuit 65 to release the parking brake 60.

前記第１切換弁４１の入口側にはチェック弁６６を備え
た油圧供給口６７が設けてあり、別の油圧源より圧油を
第１切換弁４１の入口側に供給できるようにしである。A hydraulic pressure supply port 67 equipped with a check valve 66 is provided on the inlet side of the first switching valve 41 so that pressure oil can be supplied to the inlet side of the first switching valve 41 from another hydraulic pressure source.

次に本発明に係る安全弁３６の作動について説明する。Next, the operation of the safety valve 36 according to the present invention will be explained.

左第１、第２主回路３．４のどちらが高圧となっても、
その高圧油は左シャトル弁２４で左高圧回路２２に流入
し、右第１、第２主回路７゜８のどちらが高圧となって
も、その高圧油は右シャトル弁２９で右高圧回路２７で
流入し、左右高圧回路２２．２７の高圧油はチェック弁
３１を通って安全弁３６の高圧側に流入し、その設定圧
力以上となると安全弁３６がリリーフ作動して低圧側に
流れる。No matter which of the left first and second main circuits 3.4 is at high voltage,
The high-pressure oil flows into the left high-pressure circuit 22 through the left shuttle valve 24, and regardless of which of the right first and second main circuits 7°8 is at high pressure, the high-pressure oil flows through the right shuttle valve 29 into the right high-pressure circuit 27. The high pressure oil in the left and right high pressure circuits 22, 27 passes through the check valve 31 and flows into the high pressure side of the safety valve 36, and when the pressure exceeds the set pressure, the safety valve 36 operates in relief and flows to the low pressure side.

この時、中立バイパス弁３５が遮断位置ｄとなっている
ので安全弁３６のリリーフ作動に何ら影響がない。At this time, since the neutral bypass valve 35 is in the cutoff position d, there is no effect on the relief operation of the safety valve 36.

前記安全弁３６の低圧側に流れた圧油は低圧リリーフ弁
３３、オイルクーラ３４を経て冷却回路２ｍ、６ａに流
れ、左右油圧モータ２，６を冷却した後にタンクに流れ
るので、安全弁３６でリリーフした圧油を有効利用でき
る。The pressure oil flowing to the low pressure side of the safety valve 36 flows through the low pressure relief valve 33 and the oil cooler 34 to the cooling circuits 2m and 6a, cools the left and right hydraulic motors 2 and 6, and then flows to the tank, so it is relieved by the safety valve 36. Pressure oil can be used effectively.

〔発明の効果〕〔Effect of the invention〕

左油圧トランスミッションＡの左第１、第２主回路３，
４の高圧油と右油圧トランスミッションＢの右第１、第
２主回路７，８の高圧油を同一の安全弁３６でリリーフ
できるので、各主回路の最高圧を同一にできると共に、
１つの安全弁を設ければ良いから機器重量小でコスト安
にできる。Left first and second main circuits 3 of left hydraulic transmission A,
4 and the high pressure oil in the right first and second main circuits 7 and 8 of the right hydraulic transmission B can be relieved by the same safety valve 36, the maximum pressure of each main circuit can be made the same,
Since only one safety valve is required, the weight of the equipment is small and costs can be reduced.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明の実施例を示す油圧回路図である。 Ａは左油圧トランスミッション、Ｂは右油圧トランスミ
ッション、１は左可変容量型油圧ポンプ、２は左油圧モ
ータ、３は左第１主回路、４は左第２主回路、５は右可
変容量型油圧ポンプ、６は右油圧モータ、２２は左高圧
回路、２４は左シャトル弁、２７は右高圧回路、２９は
右シャトル弁、３１はチェック弁、３６は安全弁。FIG. 1 is a hydraulic circuit diagram showing an embodiment of the present invention. A is the left hydraulic transmission, B is the right hydraulic transmission, 1 is the left variable displacement hydraulic pump, 2 is the left hydraulic motor, 3 is the left first main circuit, 4 is the left second main circuit, 5 is the right variable displacement hydraulic Pump, 6 is a right hydraulic motor, 22 is a left high pressure circuit, 24 is a left shuttle valve, 27 is a right high pressure circuit, 29 is a right shuttle valve, 31 is a check valve, and 36 is a safety valve.

Claims (1)

【特許請求の範囲】 左可変容量型油圧ポンプ１と左油圧モータ２を左第１、
第２主回路３、４で閉回路接続した左油圧トランスミッ
ションＡと、右可変容量型油圧ポンプ５と右油圧モータ
６を右第１、第２主回路７、８で閉回路接続した右油圧
トランスミッションＢを備えた閉回路油圧トランスミッ
ションの油圧回路において、 前記左第１、第２主回路３、４の高圧油を左高圧回路２
２に導入する左シャトル弁２４と、前記右第１、第２主
回路７、８の高圧油を右高圧回路２７に導入する右シャ
トル弁２９を設け、前記左高圧回路２２と右高圧回路２
７を一対のチェック弁３１、３１を介して接続し、その
一対のチェック弁３１、３１間に安全弁３６の高圧側を
接続したことを特徴とする閉回路油圧トランスミッショ
ンの油圧回路。[Claims] The left variable displacement hydraulic pump 1 and the left hydraulic motor 2 are
The left hydraulic transmission A is connected in a closed circuit through the second main circuits 3 and 4, and the right hydraulic transmission is connected in a closed circuit between the right variable displacement hydraulic pump 5 and the right hydraulic motor 6 through the right first and second main circuits 7 and 8. In the hydraulic circuit of a closed-circuit hydraulic transmission equipped with
2, and a right shuttle valve 29 that introduces high-pressure oil from the right first and second main circuits 7 and 8 into the right high-pressure circuit 27.
7 is connected via a pair of check valves 31, 31, and a high pressure side of a safety valve 36 is connected between the pair of check valves 31, 31.