JPS61124768A - Hydraulic circuit for traveling - Google Patents

Hydraulic circuit for traveling

Info

Publication number
JPS61124768A
JPS61124768A JP24158584A JP24158584A JPS61124768A JP S61124768 A JPS61124768 A JP S61124768A JP 24158584 A JP24158584 A JP 24158584A JP 24158584 A JP24158584 A JP 24158584A JP S61124768 A JPS61124768 A JP S61124768A
Authority
JP
Japan
Prior art keywords
valve
pilot
pressure
directional
switching
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP24158584A
Other languages
Japanese (ja)
Other versions
JPH0610506B2 (en
Inventor
Kimio Katsuki
勝木　公雄
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Construction Machinery Co Ltd
Original Assignee
Hitachi Construction Machinery Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Construction Machinery Co Ltd filed Critical Hitachi Construction Machinery Co Ltd
Priority to JP24158584A priority Critical patent/JPH0610506B2/en
Publication of JPS61124768A publication Critical patent/JPS61124768A/en
Publication of JPH0610506B2 publication Critical patent/JPH0610506B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/38—Control of exclusively fluid gearing
    • F16H61/40—Control of exclusively fluid gearing hydrostatic
    • F16H61/46—Automatic regulation in accordance with output requirements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/38—Control of exclusively fluid gearing
    • F16H61/40—Control of exclusively fluid gearing hydrostatic
    • F16H61/4069—Valves related to the control of neutral, e.g. shut off valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/38—Control of exclusively fluid gearing
    • F16H61/40—Control of exclusively fluid gearing hydrostatic
    • F16H61/4061—Control related to directional control valves, e.g. change-over valves, for crossing the feeding conduits

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Control Of Fluid Gearings (AREA)

Abstract

PURPOSE:To prevent the reckless drive of a car by installing a pilot type selector valve which returns a direction selecting valve to a neutral position when the pressure on the input and output sides of the direction selecting valve, is low, between the direction selecting valve and the pilot valve for operating the direction selecting valve. CONSTITUTION:Pilot selector valves 18 and 20 for switching an oil passage communicating to an operating pipot valve 4 and an oil passage communicating to a drain 15 are installed into the pilot pressurized oil passages 19 and 21 of a direction selecting valve 17 for switching the direction of revolution of a hydraulic motor 3. The pilot pressure for the selector valves 18 and 20 is obtained by introducing the pressure in the conduits on the input and output sides of the direction selecting valve 17 through conduits 24, 25, 28, and 29, and the pilot pressurized oil passage of the direction selecting valve 17 is allowed to communicate to the drain only when the pressure on the both sides is low. Therefore, it the operating pilot valve is set neutral when a car travels on a descent, the direction selecting valve is automatically switched to a neutral position where an orifice 22 communicates to the output side of the hydraulic motor 3.

Description

【発明の詳細な説明】 〔発明の利用分野〕 本発明は油圧ショベルなどの建設機械のように。[Detailed description of the invention] [Field of application of the invention] The present invention is applicable to construction machinery such as hydraulic excavators.

油圧で駆動される車両に備えられ、特に走行装置を構成
する走行用油圧回路に関するものである。The present invention relates to a hydraulic circuit for driving, which is provided in a vehicle driven by hydraulic pressure, and particularly constitutes a traveling device.

〔発明の背景〕[Background of the invention]

第２図は、従来の油圧ショベルの走行用油圧回路を示し
ている。１は可変容量油圧ポンプ（以下油圧ポンプとい
う）、２は油圧ポンプ１から油圧モータ３への圧油の流
れ方向を切換えるパイロット式方向切換弁（以下方向切
換弁という）、４はパイロット管路５により油圧ポンプ
１のレギュレータ６に接続され、かつ、パイロット管路
７，８により方向切換弁２のパイロットボートに接続さ
れたパイロット弁である。パイロット弁４は、たとえば
操作量に応じた出力圧力を発生させる２つの減圧弁によ
って構成さ゛れる。９．１０は、方向切換弁２と油圧モ
ータ３とを接続する管路１１゜１２内の最高圧力を設定
するリリーフ弁である。FIG. 2 shows a hydraulic circuit for traveling of a conventional hydraulic excavator. 1 is a variable displacement hydraulic pump (hereinafter referred to as a hydraulic pump); 2 is a pilot type directional switching valve (hereinafter referred to as a directional switching valve) that switches the flow direction of pressure oil from the hydraulic pump 1 to the hydraulic motor 3; 4 is a pilot pipe line 5 This is a pilot valve connected to the regulator 6 of the hydraulic pump 1 by means of a pilot valve 1, and connected to a pilot boat of a directional control valve 2 by means of pilot pipes 7 and 8. The pilot valve 4 is composed of, for example, two pressure reducing valves that generate an output pressure according to the manipulated variable. 9.10 is a relief valve that sets the maximum pressure in the pipes 11 and 12 that connect the directional control valve 2 and the hydraulic motor 3.

１３．１４は、それぞれ管路１１．１２とタンクＬ５と
の間に設けられた逆止弁である。１６は。Reference numerals 13 and 14 indicate check valves provided between the pipe lines 11 and 12 and the tank L5, respectively. 16 is.

油圧ポンプ１の最高吐出圧力を設定するメインリリーフ
弁である。This is a main relief valve that sets the maximum discharge pressure of the hydraulic pump 1.

この従来の走行用油圧回路において、パイロット弁４を
操作してパイロット管路５，７に圧力を生じさせると、
方向切換弁２はａ位置に切換ねり、また油圧ポンプ１の
吐出量が大きくなる。油圧ポンプｌから吐出された圧油
は、方向切換弁２のａ位置、管路１１を通して油圧モー
タ３に供給される。油圧モータ３から排出された油は、
管路１２゜方向切換弁２のａ位置を通してタンク１５に
放出される。これによりたとえば、油圧ショベルが前進
する。In this conventional travel hydraulic circuit, when the pilot valve 4 is operated to generate pressure in the pilot pipes 5 and 7,
The directional control valve 2 is switched to the a position, and the discharge amount of the hydraulic pump 1 is increased. Pressure oil discharged from the hydraulic pump 1 is supplied to the hydraulic motor 3 through the a position of the directional control valve 2 and the pipe line 11 . The oil discharged from the hydraulic motor 3 is
Line 12 is discharged into tank 15 through position a of directional valve 2. This causes, for example, a hydraulic excavator to move forward.

ところで、油圧ショベルなどの建設機械のように、油圧
で駆動される車間が急坂を降板する時には、油圧モータ
３が車体の重量によって回転されてしまう、これにより
、油圧モータ３がポンプ作用を起して管路１１の圧力が
低下し、その圧力が負圧に近くなると、タンク１５から
逆止弁１３を通して油が油圧モータ３の吸入側に補給さ
れる。By the way, when a hydraulically driven vehicle such as a construction machine such as a hydraulic excavator descends a steep slope, the hydraulic motor 3 is rotated by the weight of the vehicle body, and as a result, the hydraulic motor 3 causes a pump action. When the pressure in the conduit 11 decreases and approaches negative pressure, oil is supplied from the tank 15 to the suction side of the hydraulic motor 3 through the check valve 13.

この時、負圧の程度が大きい場合には、車体が逸走して
速度制御（油圧ポンプの吐出量に沿った速度）ができな
くなる事態を生じ、したがって運転者は車体が逸走する
前に、パイロット弁４の操作によって方向切換弁２を中
立の５位置方向に戻し、管路１２からタンク１５への排
出油゛の流出量を絞って油圧モータ３の排出側に圧力を
立てると共に、油圧ポンプ１のレギュレータ６により吐
出量を減少させるようにしている。これにより油圧モー
タには、流体圧力によりブレーキがかけられて、逸走が
防止される。このように、従来の降板におけるパイロッ
ト弁の操作は、降板する距離が長い時に、操作レバーを
適宜制御しながら走行しなければならず、それ故、操作
が煩雑になるという問題がある。At this time, if the degree of negative pressure is large, the car body will run away and speed control (speed according to the discharge amount of the hydraulic pump) will not be possible. By operating the valve 4, the directional control valve 2 is returned to the neutral position 5, the amount of discharged oil flowing from the pipe line 12 to the tank 15 is reduced, pressure is built up on the discharge side of the hydraulic motor 3, and the hydraulic pump 1 is A regulator 6 is used to reduce the discharge amount. As a result, the hydraulic motor is braked by fluid pressure to prevent it from running away. As described above, the conventional operation of the pilot valve during disembarkation has the problem that when the distance to disembark is long, the vehicle must travel while appropriately controlling the operating lever, which makes the operation complicated.

〔発明の目的〕[Purpose of the invention]

本発明は上記の問題点に鑑みなされたもので、車体の降
板時に、操作レバーによる操作を要することなく車体の
逸走を防止できる走行用油圧回路を提供することを目的
としている。The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a hydraulic circuit for traveling that can prevent the vehicle from running away without requiring any operation using a control lever when the vehicle is dismounted.

〔発明の概要〕[Summary of the invention]

本発明は上記の目的を達成するために、走行用油圧回路
において、パイロット式方向切換弁とその方向切換弁を
切換えるとパイロット弁との間にパイロット式方向切換
弁を設け、その切換弁は。In order to achieve the above object, the present invention provides a pilot type directional control valve between a pilot type directional control valve and a pilot valve when the directional control valve is switched in a travel hydraulic circuit, and the directional control valve includes a pilot type directional control valve.

方向切換弁の入力側の圧力および出力側の圧力のうちの
高い方の圧力によってパイロット弁による方向切換弁の
駆動が可能なように切換えられ、方向切換弁の入力側の
圧力および出力側の圧力の双方の圧力が低いときに、該
方向切換弁を中立位置に戻すように切換えられる構成に
したことを特徴としている。The pilot valve is switched so that the directional valve can be driven by the higher of the pressure on the input side and the pressure on the output side of the directional valve, and the pressure on the input side and the pressure on the output side of the directional valve are changed. The directional control valve is configured to be switched to return to the neutral position when both pressures are low.

〔発明の実施例〕[Embodiments of the invention]

以下本発明の一実施例を第１図により説明する。 An embodiment of the present invention will be described below with reference to FIG.

なお、図において第２図と同じ符号を付したものは、同
様なものを示している。１７は油圧ポンプ１から油圧モ
ータ３への圧油の流れ方向を切換えるパイロット式方向
切換弁（以下方向切換弁という）、１８は方向切換弁１
７の一方のパイロットボートとパイロット弁４とを接続
するパイロット管路１９に設けられた第１のパイロット
式切換弁（以下第１切換弁という）、２０は方向切換弁
１７の他方のパイロットポートとパイロット弁４とを接
続するパイロット管路２１に設けられた第２のパイロッ
ト式切換弁（以下第２切換弁という）である、方向切換
弁１７は３つの切換位置を有しており、中立位置すでは
油圧ポンプｌと油圧モータとを連通させる４つの入出力
ボートを遮断し、かつ、絞り（たとえば図示していない
スプールの切欠によって形成される）２２を設けたセン
ターバイパス通路を通して油圧ポンプｌをタンク１５に
連通させ、切換位Ｍａｌ　Ｃではそれぞれセンターバイ
パス通路を遮断し、油圧ポンプ１からの圧油を管路１１
もしくは１２を通して油圧モータ３に導き、かつ、油圧
モータ３から排出された油をタンク１５に放出させる。In the drawings, the same reference numerals as in FIG. 2 indicate the same parts. 17 is a pilot type directional control valve (hereinafter referred to as a directional control valve) that switches the flow direction of pressure oil from the hydraulic pump 1 to the hydraulic motor 3; 18 is a directional control valve 1;
A first pilot type switching valve (hereinafter referred to as a first switching valve) provided in a pilot pipe 19 connecting one pilot boat of 7 and the pilot valve 4, and 20 a pilot port of the other directional switching valve 17. The directional switching valve 17, which is a second pilot type switching valve (hereinafter referred to as the second switching valve) provided in the pilot pipe line 21 that connects the pilot valve 4, has three switching positions, including a neutral position and a neutral position. Now, the four input/output boats that connect the hydraulic pump l and the hydraulic motor are shut off, and the hydraulic pump l is connected through a center bypass passage provided with a restriction (for example, formed by a notch in the spool, not shown) 22. At the switching position Mal C, the center bypass passage is blocked, and the pressure oil from the hydraulic pump 1 is connected to the pipe line 11.
Alternatively, the oil is led to the hydraulic motor 3 through 12, and the oil discharged from the hydraulic motor 3 is discharged into the tank 15.

上記第１，２切換弁１８．２０はそれぞれ２つの切換位
置を有しており、中立位置Ｂでは方向切換弁１７のパイ
ロットポートをタンク１５に連通させ、切換位！ｉ！Ａ
では方向切換弁１７のパイロットポートをパイロット弁
４に連通させる。２３は第１のシャトル弁で。The first and second switching valves 18 and 20 each have two switching positions, and in the neutral position B, the pilot port of the directional switching valve 17 is communicated with the tank 15, and the switching position! i! A
Now, the pilot port of the directional switching valve 17 is communicated with the pilot valve 4. 23 is the first shuttle valve.

該シャトル弁２３の２つの入力ボートはそれぞれ油圧ポ
ンプ接続路（入力側）及び２つの油圧モータ接続路（出
力側）のうちの一方にパイロット管路２４．２５によっ
て接続されており、１つの出力ポートは逆止弁と絞りと
を並列に配設させた第１のスローリターン弁２６を通し
て第１切換弁１８のパイロットポートに接続されている
。２７は第２のシャトル弁で、該シャトル弁２７の２つ
の入力ポートはそれぞれ方向切換弁１７の油圧ポンプ接
続路（入力側）及び２つの油圧モータ接続路（出力側）
のうちの他方にパイロット管路２８゜２９によって接続
されており、１つの出力ポートは逆止弁と絞りとを並列
に配設させた第２のスローリターン弁３０を通して第２
切換弁２０のパイロットポートに接続されている。The two input boats of the shuttle valve 23 are each connected by a pilot line 24, 25 to one of a hydraulic pump connection (input side) and two hydraulic motor connections (output side), and one output. The port is connected to the pilot port of the first switching valve 18 through a first slow return valve 26 in which a check valve and a throttle are arranged in parallel. 27 is a second shuttle valve, and the two input ports of the shuttle valve 27 are a hydraulic pump connection path (input side) and two hydraulic motor connection paths (output side) of the directional control valve 17, respectively.
One output port is connected to the other by a pilot pipe 28 and 29, and one output port is connected to the second slow return valve 30, which has a check valve and a throttle arranged in parallel.
It is connected to the pilot port of the switching valve 20.

次に作用を説明する。Next, the action will be explained.

パイロット弁４を操作してパイロット管路５゜１９に圧
力を生じさせると、レギュレータ６により油圧ポンプ１
の吐出量が大きくなり、この吐出された圧油が絞り２２
を通ることにより方向切換弁１７の入力側（油圧ポンプ
接続路）に圧力が生じる。この圧力がパイロット管路２
４、シャトル弁２３及びスローリターン弁２６の逆止弁
を通して第１切換弁】８のパイロットポートに伝えられ
ると、第１切換弁１８がＢ位置からＡ位置に切換わり、
そのＡ位置を通してパイロット管路１９の圧力が方向切
換弁１フの一方のパイロットポートに伝えられる。それ
により方向切換弁１７がｂ位置からａ位置に切換わり、
油圧ポンプ１から吐出された圧油は、方向切換弁２２の
ａ位置及び管路１１を通して油圧モータ３に供給される
。油圧モータ３から排出された油は、管路１２．方向切
換弁のａ位置を通してタンク１５に放出される。これに
よりたとえば、油圧ショベルが前進する。Ｉした、油圧
ショベルを後退させる場合には、パイロット弁４の操作
により、パイロット管路５．２１に圧力を生じさせるこ
とで、前進の場合と同様に行なうことができる。なお、
パイロット管路１９に圧力が生じている時には、パイロ
ット管路２１はパイロット弁４により低圧（通常タンク
圧）となっており、逆の場合には同様にパイロット管路
！９が低圧となっている。When the pilot valve 4 is operated to generate pressure in the pilot line 5.19, the hydraulic pump 1 is activated by the regulator 6.
The discharge amount increases, and this discharged pressure oil flows through the throttle 22.
By passing through the directional control valve 17, pressure is generated on the input side (hydraulic pump connection path). This pressure is the pilot pipe 2
4. When the signal is transmitted to the pilot port of the first switching valve 8 through the shuttle valve 23 and the check valve of the slow return valve 26, the first switching valve 18 is switched from the B position to the A position,
Through the A position, the pressure in the pilot line 19 is transmitted to one pilot port of the directional control valve 1f. As a result, the directional control valve 17 is switched from the b position to the a position,
Pressure oil discharged from the hydraulic pump 1 is supplied to the hydraulic motor 3 through the a position of the directional control valve 22 and the pipe 11. The oil discharged from the hydraulic motor 3 is transferred to the pipe 12. It is discharged into tank 15 through position a of the directional valve. This causes, for example, a hydraulic excavator to move forward. When the hydraulic excavator is moved backward, it can be carried out in the same manner as when moving forward by operating the pilot valve 4 to generate pressure in the pilot line 5.21. In addition,
When pressure is generated in the pilot line 19, the pilot line 21 is at low pressure (normal tank pressure) due to the pilot valve 4, and in the opposite case, the pilot line 21 is at low pressure (normal tank pressure). 9 is low pressure.

また、上記の作用において、方向切換弁１７の入力側の
圧力が、パイロット管路２８、シャトル弁２７及びスロ
ーリターン弁３０の逆止弁を通して第２切換弁２０のパ
イロットポートにも伝わるため、第２切換弁２０はＢ位
置からＡ位置に切換わる。In addition, in the above action, the pressure on the input side of the directional switching valve 17 is also transmitted to the pilot port of the second switching valve 20 through the pilot pipe 28, the shuttle valve 27, and the check valve of the slow return valve 30. The two-way switching valve 20 is switched from the B position to the A position.

ところで、車輌が急坂を降板している時に、油圧モータ
３が車体の重量によって回転させられた場合には、油圧
モータ３のポンプ作用により管路１１の圧力が低下し、
それに連通されているパイロット管路２４，２５．２８
と第１．２切換弁１８．２０のパイロットポートの圧力
も低下する。By the way, when the hydraulic motor 3 is rotated by the weight of the vehicle while the vehicle is descending a steep slope, the pressure in the conduit 11 decreases due to the pumping action of the hydraulic motor 3.
Pilot pipes 24, 25, 28 connected to it
The pressure at the pilot port of the first and second switching valves 18 and 20 also decreases.

これにより第１、第２切換弁１８，２０は、それぞれＡ
位置からＢ位置に切換わり、そのＢ位置を通して方向切
換弁１７の両方のパイロットポートがタンク゛５に開放
される。従って、方向切換弁１７は、ａ位置からｂ位置
に切換わり、そのｂ位置により入力側と出力側との連通
を遮断され、油圧モータ３の排出側の管路１２にリリー
フ弁１０によって最高値が設定される高圧が生じ、油圧
モータ３に流体圧力によるブレーキが自動的にかかる。As a result, the first and second switching valves 18 and 20 respectively
From the position to the B position, both pilot ports of the directional control valve 17 are opened to the tank 5 through the B position. Therefore, the directional control valve 17 is switched from the a position to the b position, and the communication between the input side and the output side is cut off by the b position, and the relief valve 10 is applied to the pipe line 12 on the discharge side of the hydraulic motor 3 to reach the maximum value. A high pressure is generated, and the hydraulic motor 3 is automatically braked by fluid pressure.

この状態で、方向切換弁１７の入力側及び出力側のうち
の少なくとも一方側に圧力が生じると。In this state, if pressure is generated on at least one side of the input side and the output side of the directional control valve 17.

その圧力がパイロット管路２４，２５．２８を通して第
１，２切換弁１８．２０のパイロットポートに伝わり、
第１．２切換弁１８．２０が再びＢ位置からＡ位置に切
換わるため、方向切換弁１フも再びａ位置に切換わり、
油圧ポンプ１からの圧油が油圧モータ３に導かれる。The pressure is transmitted to the pilot ports of the first and second switching valves 18.20 through the pilot pipes 24, 25.28,
Since the 1st and 2nd switching valves 18 and 20 are switched from the B position to the A position again, the directional switching valve 1F is also switched to the A position,
Pressure oil from the hydraulic pump 1 is guided to the hydraulic motor 3.

なお、上記において、第１．第２切換弁１８゜２０がＡ
位置から８６ＬＭに切換わる時に、パイロットポートの
圧油がそれぞれスローリターン弁２６．３０の絞りを通
して流出されるため、第１゜第２切換弁１８．２０の切
換わりはなめらかに行なわれる。従って、方向切換弁１
７のａ位置からｂ位置への切換わりもなめらかなものと
なり、また、油圧モー′５３へブレーキをかける流体圧
力の′　上昇もゆるやかなものとなり、スムーズなブレ
ーキ感覚になる。In addition, in the above, 1. 2nd switching valve 18°20 is A
When switching from the position to 86LM, the pressure oil in the pilot port is discharged through the throttles of the slow return valves 26, 30, so that the switching between the 1st and 2nd switching valves 18, 20 is performed smoothly. Therefore, the directional control valve 1
The switching from the position a to the position b at position 7 is smooth, and the rise in the fluid pressure that applies the brake to the hydraulic motor 53 is also gradual, resulting in a smooth braking sensation.

上記したこの実施例では、パイロット弁４を切換えたま
まで、急坂を長距離降板できると共に。In this embodiment described above, it is possible to descend a steep slope for a long distance while keeping the pilot valve 4 switched.

方向切換弁１７の入出力双方の圧力が低くなった時だけ
方向切換弁１７がｂ位置に復帰するため。This is because the directional control valve 17 returns to position b only when the pressures at both the input and output sides of the directional control valve 17 become low.

坂停止からの登板及び平地走行などの動作もスムーズに
行なうことができる。Operations such as climbing from a hill stop and running on a flat surface can be performed smoothly.

なお１本発明は上記の実施例に限定されるものでないこ
とは言うまでもなく、たとえば、絞り２２を方向切換弁
１７から離れた位置のセンターバイパス通路に設けても
、同様な作用、効果を得ることができる。Note that it goes without saying that the present invention is not limited to the above-described embodiments; for example, even if the throttle 22 is provided in the center bypass passage at a position distant from the directional control valve 17, similar functions and effects can be obtained. I can do it.

〔発明の効果〕〔Effect of the invention〕

以上説明した本発明の走行用油圧回路によれば、車体の
降板時に、操作レバーによる操作を要することなく車体
の逸走を自動的に防止することができ、従来に比べて走
行操作性が向上する効果がある。According to the traveling hydraulic circuit of the present invention described above, when the vehicle is dismounted, it is possible to automatically prevent the vehicle from running away without requiring any operation using the operating lever, and the traveling operability is improved compared to the conventional one. effective.

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

第１図は本発明の走行用油圧回路の一実施例を示す回路
図、第２図は従来の油圧ショベルの走行用油圧回路を示
す回路図である。 １・・・・・・可変容量油圧ポンプ、３・・・・・・油
圧モータ。 ４・・・・・・パイロット弁、１７・・・・・・パイロ
ット式方向切換弁（方向切換弁）、１８・・・・・・第
１のパイロット式切換弁（第１切換弁）２０・・・・・
・第２のパイロット式切換弁（第２切換弁）。 第１図 第２図FIG. 1 is a circuit diagram showing an embodiment of the traveling hydraulic circuit of the present invention, and FIG. 2 is a circuit diagram showing a traveling hydraulic circuit of a conventional hydraulic excavator. 1... Variable displacement hydraulic pump, 3... Hydraulic motor. 4... Pilot valve, 17... Pilot operated directional switching valve (directional switching valve), 18... First pilot operated switching valve (first switching valve) 20.・・・・・・
- Second pilot type switching valve (second switching valve). Figure 1 Figure 2

Claims (1)

【特許請求の範囲】[Claims] 　可変容量油圧ポンプと、この油圧ポンプに接続した油
圧モータと、油圧ポンプから油圧モータへの圧油の流れ
方向を制御するパイロツト式方向切換弁と、この方向切
換弁を駆動するパイロツト弁とを有する走行用油圧回路
において、上記方向切換弁とパイロツト弁との間に、パ
イロツト式切換弁を設け、この切換弁は、上記方向切換
弁の入力側の圧力および出力側の圧力のうちの高い方の
圧力によつて上記パイロツト弁による方向切換弁の駆動
が可能なように切換えられ、上記方向切換弁の入力側の
圧力および出力側の圧力の双方の圧力が低いときに、該
方向切換弁を中立位置に戻すように切換えられることを
特徴とする走行用油圧回路。It has a variable displacement hydraulic pump, a hydraulic motor connected to the hydraulic pump, a pilot type directional switching valve that controls the flow direction of pressure oil from the hydraulic pump to the hydraulic motor, and a pilot valve that drives the directional switching valve. In the travel hydraulic circuit, a pilot type switching valve is provided between the directional switching valve and the pilot valve, and this switching valve is configured to control the higher of the pressure on the input side and the pressure on the output side of the directional switching valve. The directional control valve is switched by the pressure so that the pilot valve can drive the directional control valve, and when both the pressure on the input side and the pressure on the output side of the directional control valve are low, the directional control valve is set to neutral. A traveling hydraulic circuit characterized in that it can be switched to return to its original position.
JP24158584A 1984-11-17 1984-11-17 Hydraulic circuit for traveling Expired - Lifetime JPH0610506B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP24158584A JPH0610506B2 (en) 1984-11-17 1984-11-17 Hydraulic circuit for traveling

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP24158584A JPH0610506B2 (en) 1984-11-17 1984-11-17 Hydraulic circuit for traveling

Publications (2)

Publication Number Publication Date
JPS61124768A true JPS61124768A (en) 1986-06-12
JPH0610506B2 JPH0610506B2 (en) 1994-02-09

Family

ID=17076498

Family Applications (1)

Application Number Title Priority Date Filing Date
JP24158584A Expired - Lifetime JPH0610506B2 (en) 1984-11-17 1984-11-17 Hydraulic circuit for traveling

Country Status (1)

Country Link
JP (1) JPH0610506B2 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006283852A (en) * 2005-03-31 2006-10-19 Nabtesco Corp Traveling motor controller of construction machine
JP2006283854A (en) * 2005-03-31 2006-10-19 Nabtesco Corp Traveling motor controller of construction machine

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006283852A (en) * 2005-03-31 2006-10-19 Nabtesco Corp Traveling motor controller of construction machine
JP2006283854A (en) * 2005-03-31 2006-10-19 Nabtesco Corp Traveling motor controller of construction machine
JP4541211B2 (en) * 2005-03-31 2010-09-08 ナブテスコ株式会社 Construction machine travel motor control device

Also Published As

Publication number Publication date
JPH0610506B2 (en) 1994-02-09

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