KR20080059735A - Hydraulic system of forklift truck - Google Patents

Hydraulic system of forklift truck Download PDF

Info

Publication number
KR20080059735A
KR20080059735A KR1020060133393A KR20060133393A KR20080059735A KR 20080059735 A KR20080059735 A KR 20080059735A KR 1020060133393 A KR1020060133393 A KR 1020060133393A KR 20060133393 A KR20060133393 A KR 20060133393A KR 20080059735 A KR20080059735 A KR 20080059735A
Authority
KR
South Korea
Prior art keywords
hydraulic
lift cylinder
sensing means
hydraulic pump
cylinder
Prior art date
Application number
KR1020060133393A
Other languages
Korean (ko)
Inventor
고현기
Original Assignee
두산인프라코어 주식회사
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 두산인프라코어 주식회사 filed Critical 두산인프라코어 주식회사
Priority to KR1020060133393A priority Critical patent/KR20080059735A/en
Priority to PCT/KR2007/006782 priority patent/WO2008078941A1/en
Publication of KR20080059735A publication Critical patent/KR20080059735A/en

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F9/00—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes
    • B66F9/06—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks
    • B66F9/075—Constructional features or details
    • B66F9/20—Means for actuating or controlling masts, platforms, or forks
    • B66F9/22—Hydraulic devices or systems
    • 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
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • 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
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F15B11/17—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors using two or more pumps
    • 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
    • F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
    • F15B21/14—Energy-recuperation means
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/20576—Systems with pumps with multiple pumps
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30505—Non-return valves, i.e. check valves
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/3056—Assemblies of multiple valves
    • F15B2211/3059—Assemblies of multiple valves having multiple valves for multiple output members
    • F15B2211/30595—Assemblies of multiple valves having multiple valves for multiple output members with additional valves between the groups of valves for multiple output members
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3105—Neutral or centre positions
    • F15B2211/3116—Neutral or centre positions the pump port being open in the centre position, e.g. so-called open centre
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50518—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using pressure relief valves
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/6336—Electronic controllers using input signals representing a state of the output member, e.g. position, speed or acceleration
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/634—Electronic controllers using input signals representing a state of a valve
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/6346—Electronic controllers using input signals representing a state of input means, e.g. joystick position
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/665—Methods of control using electronic components
    • F15B2211/6651—Control of the prime mover, e.g. control of the output torque or rotational speed
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/665—Methods of control using electronic components
    • F15B2211/6654—Flow rate control
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7053—Double-acting output members
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7058—Rotary output members
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • F15B2211/7135—Combinations of output members of different types, e.g. single-acting cylinders with rotary motors
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • F15B2211/7142—Multiple output members, e.g. multiple hydraulic motors or cylinders the output members being arranged in multiple groups
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/80—Other types of control related to particular problems or conditions
    • F15B2211/88—Control measures for saving energy

Abstract

A hydraulic system of a forklift truck is provided to smoothly operate a lift cylinder by supplying hydraulic fluid of different sources to the lift cylinder as occasion demands. A hydraulic system of a forklift truck includes first and second hydraulic pumps(60,62), first and second sensing units(80,82), a bypass valve(87), and a control unit(85). The first hydraulic pump supplies hydraulic fluid to a lift cylinder(8) and a steering unit(52) through a first hydraulic line(64). The second hydraulic pump supplies the hydraulic fluid to a tilt cylinder(9) and various kinds of attachments through a second hydraulic line(66). The first sensing unit senses operation of the lift cylinder. The second sensing unit senses operation of the tilt cylinder and the attachments. The bypass valve is installed between the first and second hydraulic lines and selectively connects the first and second hydraulic lines. The control unit controls the bypass valve so as to supply the hydraulic fluid to the first hydraulic line in case of operation of the lift cylinder.

Description

지게차의 유압시스템{HYDRAULIC SYSTEM OF FORKLIFT TRUCK}HYDRAULIC SYSTEM OF FORKLIFT TRUCK}

도 1은 일반적인 지게차의 측면도,1 is a side view of a typical forklift truck,

도 2는 일반적인 지게차의 유압시스템을 나타내는 유압회로도, 2 is a hydraulic circuit diagram showing a hydraulic system of a general forklift truck;

도 3은 본 발명에 따른 지게차의 유압시스템을 나타내는 유압회로도, 3 is a hydraulic circuit diagram showing a hydraulic system of a forklift according to the present invention;

도 4는 본 발명에 따른 유압시스템의 다른 실시예를 나타내는 유압회로도이다. 4 is a hydraulic circuit diagram showing another embodiment of the hydraulic system according to the present invention.

♣ 도면의 주요 부분에 대한 부호의 설명 ♣♣ Explanation of symbols for the main parts of the drawing ♣

1: 차체 5: 마스트조립체1: body 5: mast assembly

7: 캐리지 8; 리프트 실린더7: carriage 8; Lift cylinder

9: 틸트 실린더 40: 어태치먼트9: tilt cylinder 40: attachment

60: 제 1유압펌프 60a: 제 1동력원60: first hydraulic pump 60a: first power source

62: 제 2유압펌프 62a: 제 2동력원62: second hydraulic pump 62a: second power source

64: 제 1유압라인 66: 제 2유압라인64: first hydraulic line 66: second hydraulic line

68: 프라이오러티 밸브 70: 콘트롤밸브68: privacy valve 70: control valve

72: 제 1내부통로 74: 제 2내부통로72: first internal passage 74: second internal passage

75: 드레인라인 76: 리프트스풀75: drain line 76: lift spool

77: 틸트스풀 78: 옵션스풀77: tilt spool 78: option spool

80: 제 1감지수단 82: 제 2감지수단80: first sensing means 82: second sensing means

85: 제어부 87: 바이패스 밸브85: control unit 87: bypass valve

90: 전자 클러치90: electronic clutch

본 발명은 지게차의 유압시스템에 관한 것으로, 보다 상세하게는 리프트 실린더 이외의 작업기에 최적량의 작동유만을 공급하도록 구성함으로써 각 작업기에 대량의 작동유 도입에 의한 작동유의 압손과 과열을 미연에 방지할 수 있는 지게차의 유압시스템에 관한 것이다. The present invention relates to a hydraulic system of a forklift truck, and more particularly, by supplying only an optimum amount of working oil to a work machine other than a lift cylinder, it is possible to prevent the pressure loss and overheating of the working oil due to the introduction of a large amount of working oil to each work machine. A hydraulic system of a forklift truck.

지게차는 고중량의 하물(荷物)을 들어올리고 내리거나 또는 이것을 소망하는 위치로 운반하는데 사용된다. 이러한 지게차는 도 1에 도시된 바와 같이 전방구동륜(3)과 후방조향륜(4)에 의해서 지지되는 차체(1)가 제공되며, 차체(1)의 전방에는 마스트조립체(5)가 설치된다. Forklift trucks are used to lift and unload heavy loads or to transport them to a desired location. Such a forklift is provided with a vehicle body 1 supported by the front driving wheel 3 and the rear steering wheel 4 as shown in FIG. 1, and a mast assembly 5 is installed in front of the vehicle body 1.

마스트조립체(5)는 상, 하로 이동가능한 캐리지(7)를 갖추고 있으며, 이 캐리지(7)는 마스트조립체(5)에 수직하게 설치되는 리프트 실린더(8)에 의해 상, 하로 승강가능하다. The mast assembly 5 has a carriage 7 which is movable up and down, which can be lifted up and down by a lift cylinder 8 which is installed perpendicular to the mast assembly 5.

캐리지(7)에는 한 쌍의 포크(7a) 또는 각종 어태치먼트, 예를 들어 힌지드 버켓, 사이드 쉬프트, 로드 스테빌라이저, 로테이딩 포크 등이 장착된다. 아울러 마스트조립체(5)는 틸트 실린더(9)에 의해 전방 또는 후방으로 경사지게 구성된다.The carriage 7 is equipped with a pair of forks 7a or various attachments such as hinged buckets, side shifts, road stabilizers, rotating forks and the like. In addition, the mast assembly 5 is configured to be inclined forward or backward by the tilt cylinder (9).

그리고 지게차는 마스트조립체(5)와 작업기, 예를 들면, 리프트 실린더(8)와 틸트 실린더(9)와 각종 어태치먼트들을 작동시키기 위한 유압시스템을 갖추고 있다. The forklift is equipped with a hydraulic system for operating the mast assembly 5 and the work machine, for example, the lift cylinder 8 and the tilt cylinder 9 and various attachments.

유압시스템은, 도 2에 도시된 바와 같이 유압펌프(10)를 갖는다. 유압펌프(10)는 내연기관 또는 전기모터 등과 같은 동력원(10a)에 의해 구동되며, 오일탱크(T)의 작동유를 흡입하여 고압으로 토출한다. The hydraulic system has a hydraulic pump 10 as shown in FIG. The hydraulic pump 10 is driven by a power source 10a such as an internal combustion engine or an electric motor, and sucks hydraulic oil of the oil tank T and discharges it at high pressure.

그리고 유압시스템은 메인라인(20)과 드레인라인(22)을 갖는다. 메인라인(20)은 유압펌프(10)와 연결되어 고압의 작동유를 압송한다. 아울러 드레인라인(22)은 메인라인(20)의 작동유를 오일탱크(T)로 드레인시킨다. The hydraulic system has a main line 20 and a drain line 22. The main line 20 is connected to the hydraulic pump 10 to pressurize the hydraulic oil of high pressure. In addition, the drain line 22 drains the hydraulic oil of the main line 20 to the oil tank T.

그리고 메인라인(20)과 드레인라인(22)의 사이에는 작업기용 콘트롤밸브(30)가 설치된다. 콘트롤밸브(30)는 내부통로(32)를 갖추고 있으며, 내부통로(32)는 메인라인(20)과 연결되는 도입포트(32a)와, 드레인라인(22)과 연결되는 배출포트(32b)를 갖는다.And a control valve 30 for the work machine is installed between the main line 20 and the drain line 22. The control valve 30 has an inner passage 32, and the inner passage 32 includes an inlet port 32a connected to the main line 20 and a discharge port 32b connected to the drain line 22. Have

한편, 콘트롤밸브(30)의 내부통로(32)에는 리프트스풀(34)과 틸트스풀(35)과 복수의 옵션스풀(36, 38)이 설치되어 있다. On the other hand, a lift spool 34, a tilt spool 35, and a plurality of option spools 36 and 38 are provided in the inner passage 32 of the control valve 30.

리프트스풀(34)은 운전자의 조작에 의해 절환운동하면서 내부통로(32)의 작동유를 리프트 실린더(8)에 공급한다. 따라서, 리프트 실린더(8)를 작동시킨다.The lift spool 34 supplies the hydraulic oil of the inner passage 32 to the lift cylinder 8 while switching by the driver's operation. Thus, the lift cylinder 8 is operated.

틸트스풀(35)은 운전자의 조작에 의해 절환운동하면서 내부통로(32)의 작동유를 틸트 실린더(9)에 공급한다. 따라서, 틸트 실린더(9)를 작동시킨다.The tilt spool 35 supplies the hydraulic oil of the inner passage 32 to the tilt cylinder 9 while switching by the driver's operation. Thus, the tilt cylinder 9 is operated.

옵션스풀(36, 38)은 운전자의 조작에 의해 절환운동하면서 내부통로(32)의 작동유를 각종 어태치먼트(40)에 공급한다. 따라서, 각종 어태치먼트(40)를 작동시킨다. The option spools 36 and 38 supply hydraulic fluid of the inner passage 32 to the various attachments 40 while switching by the driver's operation. Thus, various attachments 40 are operated.

다시, 도 2를 참조하면, 유압시스템의 메인라인(22)에는 프라이오러티 밸브(priority valve)(50)가 설치된다. Referring again to FIG. 2, a priority valve 50 is installed in the main line 22 of the hydraulic system.

프라이오러티 밸브(50)는, 스티어링 유닛(52)과 연결되며, 메인라인(22)의 작동유를 스티어링 유닛(52)에 우선적으로 공급한다. 특히, 스티어링 유닛(52)의 작동에 필요한 작동유를 충분히 공급한 후에 콘트롤밸브(30)로 공급하도록 구성된다. The privacy valve 50 is connected to the steering unit 52, and preferentially supplies the hydraulic oil of the main line 22 to the steering unit 52. In particular, it is configured to supply to the control valve 30 after sufficiently supplying the operating oil required for the operation of the steering unit 52.

그런데, 이러한 종래의 유압시스템은, 상기 유압펌프(10)가 대유량을 필요로하는 리프트 실린더(8)에 맞춰 대용량으로 구성되므로, 리프트 실린더(8)가 작동되지 않을 경우, 유압펌프(10)에서 토출된 대량의 작동유가 소량만 필요한 틸트 실린더(9)와 어태치먼트(40)에 도입된다는 단점이 있으며, 이러한 단점 때문에 대량의 작동유가 틸트스풀(35)과 옵션스풀(36, 38) 및 각종 오리피스와 릴리프 밸브(39)들을 통과하는 과정에서 압손(壓損)이 발생되고, 발생된 압손 때문에 작동유가 과열된다는 문제점이 있다. 특히, 작동유가 과열됨에 따라 작동유의 수명이 조기에 저하됨은 물론, 각종 유압 부품들의 수명도 단축된다는 문제점이 있다.However, such a conventional hydraulic system, since the hydraulic pump 10 is configured in a large capacity in accordance with the lift cylinder 8 requiring a large flow rate, when the lift cylinder 8 is not operated, the hydraulic pump 10 There is a drawback that the large amount of hydraulic fluid discharged from the tilt cylinder 9 and the attachment 40, which requires only a small amount, is introduced, and due to this disadvantage, a large amount of hydraulic oil is introduced into the tilt spool 35 and the optional spools 36 and 38 and various orifices. There is a problem in that a pressure loss occurs in the course of passing through the relief valves 39 and the hydraulic oil is overheated due to the generated pressure loss. In particular, as the hydraulic oil is overheated, there is a problem that the life of the hydraulic oil is lowered early and the lifetime of various hydraulic components is shortened.

한편, 이를 감안하여, 과열된 작동유를 냉각시키기 위한 오일쿨러(도시하지 않음)를 별도로 설치하기도 하지만, 이같은 경우, 오일쿨러의 설치로 인한 비용 상승의 결과를 초래하기만 한다. On the other hand, in consideration of this, an oil cooler (not shown) for cooling the overheated hydraulic fluid may be separately installed, but in such a case, only the cost of the oil cooler may be increased.

본 발명은, 상기와 같은 종래의 문제점을 해결하기 위해 안출된 것으로서, 그 목적은 리프트 실린더 이외의 작업기에 최적량의 작동유만을 공급하도록 구성함으로써 각 작업기에 대량의 작동유 도입에 의한 작동유의 압손과 과열을 미연에 방지할 수 있는 지게차의 유압시스템을 제공하는 데 있다. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and its object is to supply only an optimum amount of hydraulic oil to a work machine other than a lift cylinder, so that pressure loss and overheating of the hydraulic oil by introducing a large amount of hydraulic fluid into each work machine To provide a hydraulic system of the forklift that can prevent the in advance.

이러한 목적을 달성하기 위하여 본 발명은, 리프트 실린더와 틸트 실린더와 각종 어태치먼트 및 스티어링 유닛을 작동시키기 위한 지게차의 유압시스템에 있어서, 상기 리프트 실린더 및 상기 스티어링 유닛에 작동유를 제 1유압라인을 통해 공급하는 제 1유압펌프와; 상기 틸트 실린더와 각종 어태치먼트들에 제 2유압라인을 통해 공급하는 제 2유압펌프와; 상기 리프트 실린더가 작동 중인지를 감지하는 제 1감지수단과; 상기 틸트 실린더와 어태치먼트가 작동 중인지를 각각 감지하는 제 2감지수단과; 상기 제 1 및 제 2유압라인 사이에 설치되어 상기 제 1 및 제 2유압라인을 선택적으로 합류시키는 바이패스 밸브와; 상기 제 1감지수단에 의해 상기 리프트 실린더가 작동 중인 것으로 검출되면, 상기 제 1 및 제 2유압펌프로부터 토출되는 작동유가 합류되어 상기 제 1유압라인으로 공급되도록 상기 바이패스 밸브를 제어하는 제어부를 포함하는 것을 특징으로 한다.In order to achieve the above object, the present invention provides a hydraulic system of a forklift for operating a lift cylinder, a tilt cylinder, various attachments, and a steering unit, which supplies hydraulic oil to the lift cylinder and the steering unit through a first hydraulic line. A first hydraulic pump; A second hydraulic pump for supplying the tilt cylinder and various attachments through a second hydraulic line; First sensing means for sensing whether the lift cylinder is in operation; Second sensing means for respectively sensing whether the tilt cylinder and the attachment are in operation; A bypass valve installed between the first and second hydraulic lines to selectively join the first and second hydraulic lines; And a control unit for controlling the bypass valve so that the hydraulic oil discharged from the first and second hydraulic pumps is joined and supplied to the first hydraulic line when the lift cylinder is detected by the first sensing means. Characterized in that.

바람직하게는, 상기 제 2유압펌프로 동력을 공급하는 동력원과 상기 제 2유압펌프의 사이에 설치되어, 상기 제 2유압펌프의 동력전달을 선택적으로 차단가능한 클러치를 더 포함하며, 상기 제어부는 상기 제 1감지수단과 제 2감지수단들 모두로부터 감지신호가 입력되지 않으면, 상기 제 2유압펌프로의 동력전달이 차단되 도록 상기 클러치를 제어하는 것을 특징으로 한다. Preferably, further comprising a clutch installed between the power source for supplying power to the second hydraulic pump and the second hydraulic pump to selectively block power transmission of the second hydraulic pump, wherein the control unit When the detection signal is not input from both the first sensing means and the second sensing means, the clutch is controlled so that power transmission to the second hydraulic pump is blocked.

이하, 본 발명에 따른 지게차의 유압시스템의 바람직한 실시예를 첨부도면을 참조로하여 상세히 설명한다(종래기술과 동일한 구성요소에는 동일한 부호를 부여하여 설명한다).Best Mode for Carrying Out the Invention Preferred embodiments of the hydraulic system of a forklift truck according to the present invention will be described in detail with reference to the accompanying drawings.

먼저, 도 3을 참조하면, 본 발명의 유압시스템은, 제 1동력원(60a)에 의해 구동되는 소용량의 제 1유압펌프(60)와, 제 2동력원(62a)에 의해 구동되는 소용량의 제 2유압펌프(62)를 갖는다. 여기서, 제 1 및 제 2동력원(60a, 62a)은 전기모터 또는 내연기관 등으로 구성된다. First, referring to FIG. 3, the hydraulic system of the present invention includes a small capacity first hydraulic pump 60 driven by the first power source 60a and a small capacity second driven by the second power source 62a. It has a hydraulic pump 62. Here, the first and second power source (60a, 62a) is composed of an electric motor or an internal combustion engine or the like.

제 1유압펌프(60)와 제 2유압펌프(62) 각각은, 고정용량 타입의 기어펌프로서, 오일탱크(T)의 작동유를 흡입하여 토출한다. 여기서, 제 1유압펌프(60)와 제 2유압펌프(62) 각각으로부터 토출된 작동유 토출 유량의 합은, 종래의 대용량 유압펌프(2)(도 2참조)의 토출 유량과 동일하도록 구성된다. 특히, 각 펌프(60, 62)로부터 토출된 토출 유량의 합은, 리프트 실린더(8)를 작동시키기 충분하도록 구성된다. Each of the first hydraulic pump 60 and the second hydraulic pump 62 is a fixed displacement type gear pump, which sucks and discharges the hydraulic oil of the oil tank T. Here, the sum of the hydraulic oil discharge flow rates discharged from each of the 1st hydraulic pump 60 and the 2nd hydraulic pump 62 is comprised so that it may be equal to the discharge flow volume of the conventional large capacity hydraulic pump 2 (refer FIG. 2). In particular, the sum of the discharge flow rates discharged from the pumps 60 and 62 is configured to be sufficient to operate the lift cylinder 8.

본 발명에 따른 실시예에서의 제 1 및 제 2동력원(60a, 62a)은, 단일의 전기모터 또는 내연기관으로부터 소정의 동력분배장치를 통해 동력을 전달받도록 구성된다. 물론, 경우에 따라 제 1 및 제 2동력원(60a, 62a)이, 각기 다른 전기모터 또는 내연기관으로부터 동력을 전달받을 수도 있다. The first and second power sources 60a, 62a in the embodiment according to the invention are configured to receive power from a single electric motor or internal combustion engine via a predetermined power distribution device. Of course, in some cases, the first and second power sources 60a and 62a may receive power from different electric motors or internal combustion engines.

한편, 제 1유압펌프(60)는 제 1유압라인(64)을 가지며, 제 2유압펌프(62)는 제 2유압라인(66)을 갖는다. 여기서, 제 1유압펌프(60)의 제 1유압라인(64)에는 프 라이오러티 밸브(68)가 설치된다. 프라이오러티 밸브(68)는 스티어링 유닛(52)과 연결되며, 제 1유압펌프(60)로부터 토출되는 작동유를 스티어링 유닛(52)에 우선적으로 공급한다.On the other hand, the first hydraulic pump 60 has a first hydraulic line 64, the second hydraulic pump 62 has a second hydraulic line 66. Here, a prioty valve 68 is installed in the first hydraulic line 64 of the first hydraulic pump 60. The privacy valve 68 is connected to the steering unit 52, and preferentially supplies the hydraulic oil discharged from the first hydraulic pump 60 to the steering unit 52.

다시, 도 2를 참조하면, 본 발명의 유압시스템은, 콘트롤밸브(70)를 구비한다. 콘트롤밸브(70)는, 제 1내부통로(72)와 제 2내부통로(74)를 구비한다. Referring again to FIG. 2, the hydraulic system of the present invention includes a control valve 70. The control valve 70 includes a first inner passage 72 and a second inner passage 74.

제 1내부통로(72)는 제 1유압펌프(60)의 제 1유압라인(64)과 연결되어 제 1유압펌프(60)의 작동유를 도입하고, 제 2내부통로(74)는 제 2유압펌프(62)의 제 2유압라인(62)과 연결되어 제 2유압펌프(62)의 작동유를 도입한다. 여기서, 제 1내부통로(72)와 제 2내부통로(74)의 단부는, 드레인라인(75)을 통해 오일탱크(T)와 연결된다. 따라서 도입된 작동유를 오일탱크(T)로 드레인시킬 수 있다.The first inner passage 72 is connected to the first hydraulic line 64 of the first hydraulic pump 60 to introduce hydraulic oil of the first hydraulic pump 60, and the second inner passage 74 has a second hydraulic pressure. It is connected with the second hydraulic line 62 of the pump 62 to introduce the hydraulic oil of the second hydraulic pump 62. Here, end portions of the first inner passage 72 and the second inner passage 74 are connected to the oil tank T through the drain line 75. Therefore, the introduced hydraulic oil can be drained to the oil tank (T).

한편, 제 1내부통로(72)에는 리프트스풀(76)이 설치되어 있으며, 제 2내부통로(74)에는 틸트스풀(77)과 복수의 옵션스풀(78)이 차례로 설치되어 있다. On the other hand, a lift spool 76 is provided in the first inner passage 72, and a tilt spool 77 and a plurality of option spools 78 are provided in the second inner passage 74 in this order.

리프트스풀(76)은 운전자의 조작에 의해 절환운동하면서 제 1내부통로(72)로 도입된 제 1유압펌프(60)의 작동유를 리프트 실린더(8)에 공급한다. 따라서, 리프트 실린더(8)를 작동시킨다.The lift spool 76 supplies the hydraulic oil of the first hydraulic pump 60 introduced into the first internal passage 72 to the lift cylinder 8 while switching by the driver's operation. Thus, the lift cylinder 8 is operated.

틸트스풀(77)은 운전자의 조작에 의해 절환운동하면서 제 2내부통로(74)로 도입된 제 2유압펌프(62)의 작동유를 틸트 실린더(9)에 공급한다. 따라서, 틸트 실린더(9)를 작동시킨다.The tilt spool 77 supplies the hydraulic cylinder of the second hydraulic pump 62 introduced into the second internal passage 74 to the tilt cylinder 9 while switching by the driver's operation. Thus, the tilt cylinder 9 is operated.

옵션스풀(78)은 운전자의 조작에 의해 절환운동하면서 제 2내부통로(74)로 도입된 제 2유압펌프(62)의 작동유를 각종 어태치먼트(40)에 공급한다. 따라서, 각 종 어태치먼트(40)를 작동시킨다. The option spool 78 supplies the hydraulic fluid of the second hydraulic pump 62 introduced into the second internal passage 74 to the various attachments 40 while switching by the driver's operation. Therefore, the various attachments 40 are operated.

이러한 구성의 콘트롤밸브(70)에 의하면, 제 1내부통로(72)로 도입된 제 1유압펌프(60)의 작동유로는 리프트 실린더(8)를 작동시키고, 제 2내부통로(74)로 도입된 제 2유압펌프(62)의 작동유로는 틸트 실린더(9)와 어태치먼트(40)를 작동시키는 구조이므로, 리프트 실린더(8)와, 리프트 실린더(8)이외의 작업기, 즉 틸트 실린더(9)와 어태치먼트(40)의 작동유 공급원과 공급경로를 서로 다르게 한다. According to the control valve 70 of such a structure, the operating flow path of the 1st hydraulic pump 60 introduced into the 1st internal passage 72 operates the lift cylinder 8, and introduces into the 2nd internal passage 74. As shown in FIG. Since the hydraulic flow path of the second hydraulic pump 62 is configured to operate the tilt cylinder 9 and the attachment 40, a work machine other than the lift cylinder 8 and the lift cylinder 8, that is, the tilt cylinder 9 And the hydraulic oil supply source and the supply path of the attachment 40 are different.

따라서, 리프트 실린더(8)와, 리프트 실린더(8)이외의 작업기에 공급되는 작동유의 유량을 각각의 용량에 맞춰서 최적의 상태로 공급할 수 있게 한다. 특히, 리프트 실린더(8)이외의 작업기, 즉 틸트 실린더(9)와 어태치먼트(40)에 소량의 작동유를 최적의 상태로 공급할 수 있게 하며, 따라서 틸트 실린더(9)와 어태치먼트(40)에 필요 이상의 작동유가 대량으로 공급되는 것을 방지하고, 이에 따라 대량의 작동유 공급에 따른 작동유의 압손현상과 과열현상을 미연에 방지할 수 있다. Therefore, the flow volume of the hydraulic oil supplied to the lift cylinder 8 and the working machines other than the lift cylinder 8 can be supplied in an optimal state according to each capacity. In particular, it is possible to optimally supply a small amount of hydraulic oil to a work machine other than the lift cylinder 8, that is, the tilt cylinder 9 and the attachment 40, thus providing more than necessary to the tilt cylinder 9 and the attachment 40. It is possible to prevent the hydraulic oil from being supplied in large quantities, thereby preventing the pressure loss and overheating of the hydraulic oil caused by the large amount of hydraulic oil supply.

다시, 도 3을 참조하면, 본 발명의 유압시스템은, 리프트 실린더(8)가 작동 중인가를 감지하는 제 1감지수단(80)과, 리프트 실린더(8) 이외의 작업기, 즉 틸트 실린더(9)와 어태치먼트(40)가 작동 중인가를 각각 감지하는 제 2감지수단(82)들을 구비한다. Referring again to FIG. 3, the hydraulic system of the present invention includes a first sensing means 80 for detecting whether the lift cylinder 8 is in operation, and a work machine other than the lift cylinder 8, that is, the tilt cylinder 9. And second sensing means 82 for sensing whether the attachment 40 is in operation.

제 1감지수단(80)은, 리프트스풀(76)의 절환운동을 감지하는 위치감지센서로 구성되며, 리프트스풀(76)의 절환운동을 감지하여 상기 리프트 실린더(8)의 작동을 감지한다.The first detecting means 80 is composed of a position detection sensor for detecting a switching movement of the lift spool 76, and detects the switching movement of the lift spool 76 to detect the operation of the lift cylinder (8).

제 2감지수단(82)들은, 틸트스풀(77)과 옵션스풀(78) 각각의 절환운동을 감 지하는 위치감지센서들로 구성되며, 틸트스풀(77)과 옵션스풀(78)의 절환운동을 각각 감지하여 상기 틸트 실린더(9)와 각종 어태치먼트(40)의 작동을 감지한다.The second sensing means 82 is composed of position sensing sensors for detecting the switching motion of the tilt spool 77 and the option spool 78, respectively, and the switching motion of the tilt spool 77 and the option spool 78. Detects the respective motion of the tilt cylinder (9) and the various attachments (40).

그리고 본 발명의 유압시스템은, 제 1감지수단(80)과 제 2감지수단(82)으로부터 입력된 신호를 처리하는 제어부(85)를 구비한다.And the hydraulic system of this invention is provided with the control part 85 which processes the signal input from the 1st sensing means 80 and the 2nd sensing means 82. As shown in FIG.

제어부(85)는 마이콤와 구동회로를 내장하는 것으로, 제 1감지수단(80)에서만 신호가 입력되면, 현재 리프트 실린더(8)만 작동되는 것으로 판단하여 제어신호(S1)를 출력한다.The control unit 85 has a built-in microcomputer and a driving circuit. When a signal is input only in the first sensing unit 80, the controller 85 determines that only the lift cylinder 8 is currently operated and outputs a control signal S1.

그리고 제어부(85)는, 제 2감지수단(82)에서만 신호가 입력되거나 제 1 및 제 2감지수단(82)에서 동시에 신호가 입력되면, 현재 리프트 실린더(8)이외의 작업기, 즉 틸트 실린더(9)와 각종 어태치먼트(40)만 작동되는 것으로 판단하거나 현재 리프트 실린더(8)와 이외의 작업기가 동시에 작동되는 것으로 판단하여 제어신호(S1)를 소거(消去)한다. If a signal is input only from the second sensing means 82 or a signal is input from the first and second sensing means 82 at the same time, the control unit 85 currently has a work machine other than the lift cylinder 8, that is, a tilt cylinder ( It is determined that only 9) and the various attachments 40 are operated, or that the lift cylinder 8 and the other work machine are operated simultaneously, thereby erasing the control signal S1.

한편, 본 발명의 유압시스템은, 제어부(85)로부터 제어신호(S1)가 출력되면, 제 2유압라인(66)의 작동유를 바이패스하여 제 1유압라인(64)으로 합류시키는 바이패스 밸브(87)를 구비한다.On the other hand, the hydraulic system of the present invention, when the control signal (S1) is output from the control unit 85, bypass valve for bypassing the hydraulic oil of the second hydraulic line 66 to join the first hydraulic line (64) ( 87).

바이패스 밸브(87)는, 솔레노이드식 2위치 밸브로서, 복원위치(X)에서 제 2유압라인(66)의 작동유 흐름을 허용하고, 작동위치(Y)에서는 제 2유압라인(66)의 작동유를 바이패스 한다. 특히, 제어부(85)로부터 제어신호(S1)가 출력되면, 복원위치(X)에서 작동위치(Y)로 절환되면서 제 2유압라인(66)의 작동유를 바이패스하고, 바이패스된 작동유를 제 1유압라인(64)으로 합류시킨다. The bypass valve 87 is a solenoid two-position valve that allows the hydraulic oil to flow in the second hydraulic line 66 in the restoring position X, and the hydraulic oil in the second hydraulic line 66 in the operating position Y. Bypass. In particular, when the control signal S1 is output from the control unit 85, the hydraulic oil of the second hydraulic line 66 is bypassed while switching from the restoring position X to the operating position Y, and the bypassed hydraulic oil is removed. 1 to the hydraulic line (64).

여기서, 바이패스 밸브(87)는, 바이패스된 작동유를 제 1유압라인(64)으로 합류시키는 바이패스라인(87a)을 구비함은 물론이다. 그리고 바이패스 밸브(87)는, 제어부(85)의 제어신호(S1)가 소거되면, 일측에 부설되는 스프링(87b)에 의해 복원위치(X)로 복귀되면서 작동유의 바이패스를 중단함은 물론이다. Here, of course, the bypass valve 87 has a bypass line 87a for joining the bypassed hydraulic oil to the first hydraulic line 64. When the control signal S1 of the control unit 85 is erased, the bypass valve 87 returns to the restoring position X by the spring 87b attached to one side and stops the bypass of the hydraulic oil. to be.

이러한 바이패스 밸브(87)에 의하면, 제어부(85)로부터 제어신호(S1)가 출력됨에 따라 제 2유압라인(66)의 작동유를 제 1유압라인(64)으로 합류시킴으로써, 리프트 실린더(8)의 작동에 따라 제 2유압펌프(62)의 작동유가 제 1유압펌프(60)와 합쳐질 수 있게 하고, 리프트 실린더(8)의 작동에 따라 제 2유압펌프(62)의 작동유가 제 1유압펌프(60)와 합쳐질 수 있게 함으로써, 대량의 작동유가 콘트롤밸브(70)의 제 1내부통로(72)로 도입될 수 있게 하며, 대량의 작동유가 제 1내부통로(72)로 도입됨에 따라 대량의 작동유가 리프트 실린더(8)에 공급되면서 상기 리프트 실린더(8)를 원활하게 작동시킬 수 있게 한다. According to the bypass valve 87, the hydraulic cylinder of the second hydraulic line 66 is joined to the first hydraulic line 64 as the control signal S1 is output from the control unit 85, whereby the lift cylinder 8 The operating oil of the second hydraulic pump 62 can be combined with the first hydraulic pump 60 in accordance with the operation of the hydraulic oil, and the hydraulic oil of the second hydraulic pump 62 is supplied to the first hydraulic pump in accordance with the operation of the lift cylinder 8. By being combined with (60), a large amount of hydraulic oil can be introduced into the first inner passage 72 of the control valve 70, and a large amount of hydraulic oil is introduced into the first inner passage 72 The hydraulic oil is supplied to the lift cylinder 8 to smoothly operate the lift cylinder 8.

다시, 도 3을 참조하면, 본 발명의 유압시스템은, 차량의 엔진 회전수를 검출하는 제 3감지수단(88)과, 차량의 주행속도를 검출하는 제 4감지수단(89)을 구비한다. Referring again to FIG. 3, the hydraulic system of the present invention includes third sensing means 88 for detecting the engine speed of the vehicle and fourth sensing means 89 for detecting the traveling speed of the vehicle.

제 3감지수단(88)은, 회전감지센서로 구성되며, 차량의 엔진 회전수를 검출하여 제어부(85)에 입력시킨다.The third detecting means 88 is constituted by a rotation sensor, and detects the engine speed of the vehicle and inputs it to the control unit 85.

제 4감지수단(89)은, 차속감지센서로 구성되며, 차량의 주행속도를 감지하여 제어부(85)에 입력시킨다.The fourth detecting means 89 is composed of a vehicle speed detecting sensor, and detects the traveling speed of the vehicle and inputs it to the controller 85.

한편, 제어부(85)는, 상기 리프트 실린더(8)의 작동 중 상기 제 3감지수 단(88)으로부터 입력된 엔진 회전수가 기설정된 기준치보다 작은 경우 및 상기 제 4감지수단(89)으로부터 입력된 차량의 주행속도가 기설정된 범위를 벗어나는 경우 중 어느 하나인 경우 상기 제 1 및 제 2유압라인(64, 66)의 합류가 해제되도록 상기 바이패스 밸브(87)를 제어한다.On the other hand, the control unit 85, the engine rotational speed input from the third detection stage 88 during the operation of the lift cylinder 8 is less than the predetermined reference value and the input from the fourth sensing means (89) When the driving speed of the vehicle is outside the preset range, the bypass valve 87 is controlled to release the merging of the first and second hydraulic lines 64 and 66.

따라서, 차량의 엔진(도시하지 않음)의 회전수가 기설정된 기준치보다 작을 경우, 예를 들면, 아이들 상태일 경우, 리프트 실린더(8)를 작동시키고자 사용자가 조작기를 조작하더라도 엔진의 과도한 부하에 따른 엔진 스톨(Stall) 현상을 방지하기 위해 제 1 및 제 2유압라인(64, 66)의 합류를 해제한다.Therefore, when the number of revolutions of the engine of the vehicle (not shown) is smaller than the predetermined reference value, for example, in the idle state, even if the user operates the manipulator to operate the lift cylinder 8, The confluence of the first and second hydraulic lines 64 and 66 is released to prevent engine stall.

또한, 차량의 주행속도가 기설정된 범위보다 고속인 경우, 리프트 실린더(8)의 작동에 따른 안전문제를 고려하여 사용자가 조작기를 조작하더라도 리프트 실린더(8)의 작동유 도입을 다소 저감시킬 수 있도록 제 1 및 제 2유압라인(64, 66)의 합류를 해제한다.In addition, when the traveling speed of the vehicle is higher than the preset range, in consideration of safety problems caused by the operation of the lift cylinder 8, even if the user operates the manipulator, the introduction of the hydraulic oil of the lift cylinder 8 may be reduced to some extent. The confluence of the first and second hydraulic lines 64 and 66 is released.

또한, 차량의 주행속도가 기설정된 범위보다 저속인 경우, 엔진에 과도한 부하에 따른 엔진 스톨 현상을 고려하여 틸트 실린더(9) 및 어태치먼트(40)를 작동시키더라도 엔진에 과도한 부하가 가해지지 않도록 제 1 및 제 2유압라인(64, 66)의 합류를 해제한다.In addition, when the driving speed of the vehicle is lower than the preset range, even if the tilt cylinder 9 and the attachment 40 are operated in consideration of the engine stall phenomenon caused by the excessive load on the engine, it is necessary to prevent excessive load on the engine. The confluence of the first and second hydraulic lines 64 and 66 is released.

다음으로, 이와 같은 구성을 갖는 본 발명의 작동예를 상세하게 살펴본다. 먼저, 차량이 공회전(Idle)하는 상태를 살펴보면, 제 1동력원(60a)과 제 2동력원(62a)이 구동하면서 제 1유압펌프(60)와 제 2유압펌프(62)를 작동시키며, 작동되는 제 1 및 제 2유압펌프(60, 62)는 작동유를 토출한다. Next, look at the operation example of the present invention having such a configuration in detail. First, referring to a state in which the vehicle idles, the first power source 60a and the second power source 62a are driven to operate the first hydraulic pump 60 and the second hydraulic pump 62. The first and second hydraulic pumps 60 and 62 discharge hydraulic oil.

이때, 제 1 및 제 2유압펌프(60, 62)의 작동유는, 각각 제 1유압라인(64)과 제 2유압라인(66)을 통해 콘트롤밸브(70)의 제 1내부통로(72)와 제 2내부통로(74)로 각각 유입되고, 유입된 작동유는 드레인라인(75)을 통해 오일탱크(T)로 리턴된다. At this time, the hydraulic fluid of the first and second hydraulic pumps 60 and 62 is connected to the first internal passage 72 of the control valve 70 through the first hydraulic line 64 and the second hydraulic line 66, respectively. Each of the second inner passage 74 flows in, and the introduced hydraulic oil is returned to the oil tank T through the drain line 75.

다음으로, 운전자가 조향하는 경우를 살펴본다. 먼저, 운전자가 조향하면, 프라이오러티 밸브(68)가 작동하면서 제 1유압펌프(60)의 작동유를 스티어링 유닛(52)에 우선적으로 공급하고, 공급된 작동유는 스티어링 유닛(52)을 작동시키면서 차량을 조향가능하게 한다.Next, the case in which the driver steers will be described. First, when the driver steers, the priority valve 68 is operated and the hydraulic oil of the first hydraulic pump 60 is preferentially supplied to the steering unit 52, and the supplied hydraulic oil operates the steering unit 52. Makes the vehicle steerable.

다음으로, 운전자가 리프트 실린더(8)를 조작하는 경우를 살펴본다. 운전자가 리프트스풀(76)을 조작한다. 그러면, 콘트롤밸브(70)의 제 1내부통로(72)로 도입된 제 1유압펌프(60)의 작동유가 리프트스풀(76)을 통해 리프트 실린더(8)로 공급되고, 공급된 작동유는 리프트 실린더(8)를 작동시킨다.Next, a case in which the driver operates the lift cylinder 8 will be described. The driver operates the lift spool 76. Then, the hydraulic oil of the first hydraulic pump 60 introduced into the first inner passage 72 of the control valve 70 is supplied to the lift cylinder 8 through the lift spool 76, and the supplied hydraulic oil is lift cylinder. Activate (8).

한편, 운전자가 리프트스풀(76)을 조작하면, 제 1감지수단(80)이 이를 감지하는데, 이때 감지된 신호는 제어부(85)에 입력되고, 감지신호가 입력된 제어부(85)는 현재 리프트 실린더(8)만 작동되는 것으로 판단하여 제어신호(S1)를 바이패스 밸브(87)에 입력시킨다. On the other hand, when the driver manipulates the lift spool 76, the first detection means 80 detects this, and the detected signal is input to the control unit 85, the control unit 85 input the detection signal is currently lifted It is determined that only the cylinder 8 is operated, and the control signal S1 is input to the bypass valve 87.

그리고 제어신호(S1)가 입력된 바이패스 밸브(87)는 복원위치(X)에서 작동위치(Y)로 절환운동하면서 제 2유압펌프(62)의 작동유를 바이패스하여 콘트롤밸브(70)의 제 1내부통로(72)로 도입시키고, 도입된 작동유는 제 1유압펌프(60)와 함께 합류되면서 리프트 실린더(8)로 공급되고, 공급된 대량의 작동유는 리프트 실린 더(8)를 원활하게 작동시킨다.In addition, the bypass valve 87 into which the control signal S1 is input, bypasses the hydraulic fluid of the second hydraulic pump 62 while switching from the restoring position X to the operating position Y, thereby bypassing the control valve 70. Introduced into the first inner passage (72), the introduced hydraulic oil is supplied to the lift cylinder (8) while being joined with the first hydraulic pump (60), and the supplied large amount of hydraulic oil smoothly lifts the lift cylinder (8) It works.

다음으로, 운전자가 리프트 실린더(8)이외의 작업기, 즉 틸트 실린더(9)와 어태치먼트(40)를 조작하는 경우를 살펴본다. 운전자가 틸트스풀(77) 또는 옵션스풀(78)을 조작한다. 그러면, 콘트롤밸브(70)의 제 2내부통로(74)로 도입된 제 2유압펌프(62)의 작동유가 틸트스풀(77)을 통해 틸트 실린더(9) 또는 어태치먼트(40)로 공급되고, 공급된 작동유는 틸트 실린더(9) 또는 어태치먼트(40)를 작동시킨다.Next, the case in which the driver operates the work machine other than the lift cylinder 8, that is, the tilt cylinder 9 and the attachment 40 will be described. The driver operates the tilt spool 77 or the option spool 78. Then, the hydraulic oil of the second hydraulic pump 62 introduced into the second inner passage 74 of the control valve 70 is supplied to the tilt cylinder 9 or the attachment 40 through the tilt spool 77, and is supplied. The hydraulic fluid thus operated operates the tilt cylinder 9 or the attachment 40.

한편, 운전자가 틸트스풀(77) 또는 옵션스풀(78)을 조작하면, 제 2감지수단(82)이 이를 감지하는데, 이때 감지된 신호는 제어부(85)에 입력되고, 감지신호가 입력된 제어부(85)는 현재 리프트 실린더(8)이외의 작업기가 작동되는 것으로 판단하여 제어신호(S1)를 소거한 상태를 유지한다. On the other hand, when the driver manipulates the tilt spool 77 or the option spool 78, the second detection means 82 detects this, the detected signal is input to the control unit 85, the control unit input the detection signal Reference numeral 85 determines that a work machine other than the lift cylinder 8 is currently operated and maintains a state in which the control signal S1 is erased.

따라서, 상기 바이패스 밸브(87)는 복원위치(X)의 상태를 유지하면서 제 2유압라인(66)의 작동유 흐름을 허용하고, 작동유 흐름을 허용함에 따라 상기 작동유는 콘트롤밸브(70)의 제 2내부통로(74)를 통해 틸트 실린더(9) 또는 어태치먼트(40)로 공급되면서 상기 틸트 실린더(9) 또는 어태치먼트(40)를 작동시킨다.Accordingly, the bypass valve 87 permits the flow of the hydraulic oil in the second hydraulic line 66 while maintaining the state of the restoring position X, and the hydraulic fluid flows through the control valve 70 by allowing the hydraulic oil flow. 2, the tilt cylinder 9 or the attachment 40 is operated while being supplied to the tilt cylinder 9 or the attachment 40 through the inner passage 74.

다음으로, 운전자가 리프트 실린더(8)와, 리프트 실린더(8)이외의 작업기(9, 40)를 동시에 조작하는 경우를 살펴본다. 먼저, 운전자가 리프트스풀(76)과, 리프트스풀(76)이외의 스풀, 즉 틸트스풀(77) 또는 옵션스풀(78)을 동시에 조작한다. Next, the case where a driver operates the lift cylinder 8 and the work machines 9 and 40 other than the lift cylinder 8 simultaneously is considered. First, the driver operates the lift spool 76 and the spools other than the lift spool 76, that is, the tilt spool 77 or the option spool 78 at the same time.

그러면, 콘트롤밸브(70)의 제 2내부통로(74)로 도입된 제 1유압펌프(60)의 작동유는 리프트 실린더(8)로 공급되면서 상기 리프트 실린더(8)를 작동시킨다. 그리고 콘트롤밸브(70)의 제 2내부통로(74)로 도입된 제 2유압펌프(62)의 작동유는 틸트 실린더(9) 또는 어태치먼트(40)로 공급되면서 상기 틸트 실린더(9) 또는 어태치먼트(40)를 작동시킨다.Then, the hydraulic oil of the first hydraulic pump 60 introduced into the second inner passage 74 of the control valve 70 is supplied to the lift cylinder 8 to operate the lift cylinder 8. The hydraulic oil of the second hydraulic pump 62 introduced into the second inner passage 74 of the control valve 70 is supplied to the tilt cylinder 9 or the attachment 40 while being supplied to the tilt cylinder 9 or the attachment 40. ).

한편, 운전자가 리프트스풀(76)과, 리프트스풀(76)이외의 스풀(77, 78)을 동시에 조작하면, 제 1감지수단(80)과 제 2감지수단(82)이 이를 감지하는데, 이때 감지된 신호는 제어부(85)에 입력되고, 감지신호가 입력된 제어부(85)는 현재 리프트 실린더(8)와 리프트 실린더(8)이외의 작업기가 작동되는 것으로 판단하여 제어신호(S1)를 소거한 상태를 유지한다. On the other hand, when the driver operates the lift spool 76 and the spools 77 and 78 other than the lift spool 76 at the same time, the first sensing means 80 and the second sensing means 82 detect this. The detected signal is input to the control unit 85, and the control unit 85 in which the detection signal is input erases the control signal S1 by determining that a work machine other than the lift cylinder 8 and the lift cylinder 8 is currently operated. Stay in one state.

따라서, 상기 바이패스 밸브(87)는 복원위치(X)의 상태를 유지하면서 제 2유압라인(66)의 작동유 흐름을 허용하고, 작동유 흐름을 허용함에 따라 제 2유압펌프(62)의 작동유는 콘트롤밸브(70)의 제 2내부통로(74)로만 유입되며, 제 1유압펌프(60)의 작동유는 콘트롤밸브(70)의 제 1내부통로(72)로 유입된다.Accordingly, the bypass valve 87 allows the hydraulic oil flow of the second hydraulic line 66 while maintaining the state of the restoring position X, and the hydraulic oil of the second hydraulic pump 62 is allowed by the hydraulic oil flow. Only the second internal passage 74 of the control valve 70 flows in, and the hydraulic fluid of the first hydraulic pump 60 flows into the first internal passage 72 of the control valve 70.

따라서, 제 1유압펌프(60)의 작동유는 리프트 실린더(8)만 작동시키고, 제 2유압펌프(62)의 작동유는 틸트 실린더(9) 또는 어태치먼트(40)만 작동시킨다.Therefore, the hydraulic oil of the first hydraulic pump 60 operates only the lift cylinder 8, and the hydraulic oil of the second hydraulic pump 62 operates only the tilt cylinder 9 or the attachment 40.

이와 같은 구성의 본 발명에 의하면, 리프트 실린더(8)와, 리프트 실린더(8)이외의 작업기(9, 40)에 공급되는 작동유의 공급원과 공급경로를 각기 다르게 구성하므로, 비교적 소유량이 필요한 리프트 실린더(8)이외의 작업기(9, 40)에 최적량의 작동유를 공급할 수 있게 된다. 따라서, 리프트 실린더(8)이외의 작업기(9, 40)에 필요 이상의 작동유가 대량으로 공급되는 것을 원천적으로 차단할 수 있다. According to the present invention having such a configuration, since the supply source and the supply path of the hydraulic oil supplied to the working cylinders 9 and 40 other than the lift cylinder 8 and the lift cylinder 8 are configured differently, a lift cylinder requiring a relatively small amount of flow is required. It is possible to supply the optimum amount of hydraulic oil to the work machines 9 and 40 other than (8). Therefore, it is possible to fundamentally block the supply of a larger amount of hydraulic fluid than necessary to the work machines 9 and 40 other than the lift cylinder 8.

또한, 본 발명은, 리프트 실린더(8)와, 리프트 실린더(8)이외의 작업기(9, 40)의 작동유 공급원과 공급경로를 각기 다르게 구성하되, 대유량이 요구되는 리프 트 실린더(8)가 작동되는 경우에는 각기 다른 공급원의 작동유를 서로 병합하여 상기 리프트 실린더(8)에 공급하는 구조를 가지므로, 리프트 실린더(8)를 원활하게 작동시킬 수 있게 된다.The present invention also provides a lift cylinder 8 and a lift cylinder 8 having a different flow rate and a supply path for the working oil 9 and 40 of the work machines 9 and 40 other than the lift cylinder 8. In the case of operation, since the hydraulic oil of different sources is merged with each other and supplied to the lift cylinder 8, the lift cylinder 8 can be smoothly operated.

다음으로, 본 발명에 따른 유압시스템의 다른 실시예를 나타내는 도면이 도시되어 있다. Next, a diagram showing another embodiment of the hydraulic system according to the invention is shown.

다른 실시예의 유압시스템은, 제 2동력원(62a)으로부터 제 2유압펌프(62)로 전달되는 동력을 단속(斷續)하는 전자 클러치(90)를 더 구비한다.The hydraulic system of another embodiment further includes an electromagnetic clutch 90 which interrupts the power transmitted from the second power source 62a to the second hydraulic pump 62.

전자 클러치(90)는, 평소에는 제 2동력원(62a)과 제 2유압펌프(62)를 연결하여 상기 제 2동력원(62a)으로부터 제 2유압펌프(62)로의 동력 전달을 허용한다. 그러나 전기신호가 인가되면, 제 2동력원(62a)과 제 2유압펌프(62)의 연결을 끊어서 제 2동력원(62a)으로부터 제 2유압펌프(62)로의 동력 전달을 차단한다.The electromagnetic clutch 90 normally connects the second power source 62a and the second hydraulic pump 62 to allow power transmission from the second power source 62a to the second hydraulic pump 62. However, when the electric signal is applied, the second power source 62a and the second hydraulic pump 62 are disconnected to cut off power transmission from the second power source 62a to the second hydraulic pump 62.

그리고 다른 실시예의 유압시스템은, 제 1감지수단(80)과 제 2감지수단(82)들과 제 3감지수단(88)과 제 4감지수단(89)으로부터 입력된 신호를 처리하는 제어부(85)를 구비하되, 상기 제어부(85)는 제 1감지수단(80)과 제 2감지수단(82)들 모두로부터 동시에 신호가 입력되지 않으면, 현재 차량의 모든 작업기(8, 9, 40)가 작동을 멈춘 것으로 판단하여 동력차단신호(S2)를 출력한다. And the hydraulic system of another embodiment, the control unit 85 for processing the signal input from the first sensing means 80, the second sensing means 82, the third sensing means 88 and the fourth sensing means (89) If the signal is not input simultaneously from both the first sensing means 80 and the second sensing means 82, all the work machines (8, 9, 40) of the current vehicle is operated. It is determined that the stop and output the power cut off signal (S2).

특히, 출력된 동력차단신호(S2)를 전자 클러치(90)에 인가하여, 상기 전자 클러치(90)로 하여금 제 2동력원(62a)과 제 2유압펌프(62)의 연결을 끊어서 제 2동력원(62a)으로부터 제 2유압펌프(62)로의 동력 전달을 차단하게 한다.In particular, the output power cut-off signal S2 is applied to the electromagnetic clutch 90, thereby causing the electromagnetic clutch 90 to disconnect the second power source 62a and the second hydraulic pump 62, thereby providing a second power source ( To stop the transmission of power from 62a) to the second hydraulic pump 62;

또한, 제어부(85)는, 제 3감지수단(88)과 제 4감지수단(89)으로부터 입력된 신호를 처리하되, 리프트 실린더(8)의 작동 중 상기 제 3감지수단(88)으로부터 입력된 엔진 회전수가 기설정된 기준치보다 작은 경우 및 상기 제 4감지수단(89)으로부터 입력된 차량의 주행속도가 기설정된 범위를 벗어나는 경우 중에, 어느 하나인 경우 상기 제 2유압펌프(62)의 동력전달이 중지되도록 상기 클러치(90)를 제어한다. In addition, the control unit 85 processes the signals input from the third sensing means 88 and the fourth sensing means 89, but is input from the third sensing means 88 during the operation of the lift cylinder 8. When the engine speed is smaller than the preset reference value and when the running speed of the vehicle input from the fourth sensing means 89 is out of the preset range, the power transmission of the second hydraulic pump 62 is The clutch 90 is controlled to stop.

따라서, 차량의 엔진이 기설정된 기준치보다 작을 경우, 예를 들면, 아이들 상태일 경우, 리프트 실린더(8)를 작동시키고자 사용자가 조작기를 조작하더라도 엔진의 과도한 부하에 따른 엔진 스톨(Stall) 현상을 방지하기 위해 제 2유압펌프(62)의 구동을 정지시키거나 또는 제 1 및 제 2유압라인(64, 66)의 합류를 해제한다.Therefore, when the engine of the vehicle is smaller than the preset reference value, for example, in the idle state, even if the user operates the manipulator to operate the lift cylinder 8, the engine stall phenomenon according to the excessive load of the engine is prevented. In order to prevent it, the driving of the second hydraulic pump 62 is stopped or the joining of the first and second hydraulic lines 64 and 66 is released.

또한, 차량의 주행속도가 기설정된 범위보다 고속인 경우, 리프트 실린더(8)의 작동에 따른 안전문제를 고려하여 사용자가 조작기를 조작하더라도 리프트 실린더(8)의 작동유 도입을 다소 저감시킬 수 있도록 제 2유압펌프(62)의 구동을 정지시키거나 또는 제 1 및 제 2유압라인(64, 66)의 합류를 해제한다. In addition, when the traveling speed of the vehicle is higher than the preset range, in consideration of safety problems caused by the operation of the lift cylinder 8, even if the user operates the manipulator, the introduction of the hydraulic oil of the lift cylinder 8 may be reduced to some extent. The driving of the second hydraulic pump 62 is stopped or the first and second hydraulic lines 64 and 66 are not joined.

또한, 차량의 주행속도가 기설정된 범위보다 저속인 경우, 엔진에 과도한 부하에 따른 엔진 스톨 현상을 고려하여 틸트 실린더(9) 및 어태치먼트(40)를 작동시키더라도 엔진에 과도한 부하가 가해지지 않도록 제 2유압펌프(62)의 구동을 정지시키거나 또는 제 1 및 제 2유압라인(64, 66)의 합류를 해제한다.  In addition, when the driving speed of the vehicle is lower than the preset range, even if the tilt cylinder 9 and the attachment 40 are operated in consideration of the engine stall phenomenon caused by the excessive load on the engine, it is necessary to prevent excessive load on the engine. The driving of the second hydraulic pump 62 is stopped or the first and second hydraulic lines 64 and 66 are not joined.

이러한 다른 실시예의 본 발명에 의하면, 작업기(8, 9, 40)의 사용 여부에 따라 제 2유압펌프(62)의 작동을 제어함으로써, 제 2유압펌프(62)의 작동에 따른 작동유의 압력손실을 최소화시킬 수 있다. According to the present invention of this other embodiment, by controlling the operation of the second hydraulic pump 62 in accordance with the use of the work machine (8, 9, 40), the pressure loss of the hydraulic fluid according to the operation of the second hydraulic pump 62 Can be minimized.

또한, 작업기(8, 9, 40)의 사용 여부에 따라 제 2유압펌프(62)의 작동을 제어함으로써, 제 2동력원(62a)에 가해지는 작동 부하를 최소화시킬 수 있으며, 따라서, 에너지 소비를 최소화시킬 수 있다. In addition, by controlling the operation of the second hydraulic pump 62 in accordance with the use of the work machine 8, 9, 40, it is possible to minimize the operating load applied to the second power source 62a, thus reducing energy consumption. It can be minimized.

이상에서는 본 발명의 바람직한 실시예를 예시적으로 설명하였으나, 본 발명의 범위는 이와 같은 특정 실시예에만 한정되는 것은 아니며, 특허청구범위에 기재된 범주내에서 적절하게 변경 가능한 것이다. Although the preferred embodiments of the present invention have been described above by way of example, the scope of the present invention is not limited to these specific embodiments, and may be appropriately changed within the scope of the claims.

이상에서 살펴본 바와 같이, 본 발명에 따른 지게차의 유압시스템은, 리프트 실린더와, 리프트 실린더이외의 작업기에 공급되는 작동유의 공급원과 공급경로를 각기 다르게 구성함으로써, 적은 유량이 필요한 리프트 실린더이외의 작업기에 적량의 작동유를 공급할 수 있게 된다. 따라서, 리프트 실린더이외의 작업기에 필요 이상의 작동유가 대량으로 공급되는 것을 원천적으로 차단할 수 있으며, 이에 따라 작동유의 대량 공급에 따른 작동유의 압손과 과열을 미연에 방지할 수 있는 효과가 있다. As described above, the hydraulic system of the forklift according to the present invention comprises a lift cylinder, a working source other than the lift cylinder, and a supply source and a supply path of the hydraulic oil supplied to a work machine other than the lift cylinder, so that the work machine other than the lift cylinder is required. It is possible to supply an appropriate amount of hydraulic oil. Therefore, it is possible to fundamentally block the supply of a larger amount of hydraulic fluid than necessary to the work machine other than the lift cylinder, thereby preventing the pressure loss and overheating of the hydraulic fluid due to the large supply of the hydraulic oil.

또한, 본 발명의 유압시스템은, 리프트 실린더와, 리프트 실린더이외의 작업기의 작동유 공급원과 공급경로를 각기 다르게 구성하되, 필요에 따라 각기 다른 공급원의 작동유를 서로 병합하여 상기 리프트 실린더에 공급하는 구조를 가지므로, 리프트 실린더를 원활하게 작동시킬 수 있는 효과가 있다. In addition, the hydraulic system of the present invention, the hydraulic cylinder supply source and the supply path of the working cylinder other than the lift cylinder, and the lift cylinder is configured differently, if necessary to merge the hydraulic fluid of different sources to supply to the lift cylinder structure Since there is an effect that can operate the lift cylinder smoothly.

Claims (4)

리프트 실린더(8)와 틸트 실린더(9)와 각종 어태치먼트(40) 및 스티어링 유닛(52)을 작동시키기 위한 지게차의 유압시스템에 있어서,In the hydraulic system of the forklift for operating the lift cylinder 8, the tilt cylinder 9, the various attachments 40 and the steering unit 52, 상기 리프트 실린더(8) 및 상기 스티어링 유닛(52)에 작동유를 제 1유압라인(64)을 통해 공급하는 제 1유압펌프(60)와; A first hydraulic pump (60) for supplying hydraulic oil to the lift cylinder (8) and the steering unit (52) through a first hydraulic line (64); 상기 틸트 실린더(9)와 각종 어태치먼트(40)들에 제 2유압라인(66)을 통해 공급하는 제 2유압펌프(62)와; A second hydraulic pump 62 for supplying the tilt cylinder 9 and various attachments 40 through a second hydraulic line 66; 상기 리프트 실린더(8)가 작동 중인지를 감지하는 제 1감지수단(80)과; First sensing means (80) for sensing whether the lift cylinder (8) is in operation; 상기 틸트 실린더(9)와 어태치먼트(40)가 작동 중인지를 각각 감지하는 제 2감지수단(82)과; Second sensing means (82) for respectively sensing whether the tilt cylinder (9) and the attachment (40) are in operation; 상기 제 1 및 제 2유압라인(64, 66) 사이에 설치되어 상기 제 1 및 제 2유압라인(64, 66)을 선택적으로 합류시키는 바이패스 밸브(87)와;A bypass valve (87) installed between the first and second hydraulic lines (64, 66) for selectively joining the first and second hydraulic lines (64, 66); 상기 제 1감지수단(80)에 의해 상기 리프트 실린더(8)가 작동 중인 것으로 검출되면, 상기 제 1 및 제 2유압펌프(60, 62)로부터 토출되는 작동유가 합류되어 상기 제 1유압라인(64)으로 공급되도록 상기 바이패스 밸브(87)를 제어하는 제어부(85)를 포함하는 것을 특징으로 하는 지게차의 유압시스템.When it is detected by the first sensing means 80 that the lift cylinder 8 is in operation, the hydraulic oil discharged from the first and second hydraulic pumps 60 and 62 joins the first hydraulic line 64. Hydraulic control system of the forklift, characterized in that it comprises a control unit (85) for controlling the bypass valve (87) to be supplied to. 제 1항에 있어서,The method of claim 1, 상기 제 2유압펌프(62)로 동력을 공급하는 동력원과 상기 제 2유압펌프(62) 의 사이에 설치되어, 상기 제 2유압펌프(62)의 동력전달을 선택적으로 차단가능한 클러치(90)를 더 포함하며, The clutch 90 is installed between the power source for supplying power to the second hydraulic pump 62 and the second hydraulic pump 62 to selectively block power transmission of the second hydraulic pump 62. More, 상기 제어부(85)는 상기 제 1감지수단(80)과 제 2감지수단(82)들 모두로부터 감지신호가 입력되지 않으면, 상기 제 2유압펌프(62)로의 동력전달이 차단되도록 상기 클러치(90)를 제어하는 것을 특징으로 하는 지게차의 유압시스템.When the detection signal is not input from both the first sensing means 80 and the second sensing means 82, the control unit 85 stops power transmission to the second hydraulic pump 62. Hydraulic system of the forklift, characterized in that for controlling. 제 2항에 있어서, The method of claim 2, 상기 차량의 엔진 회전수를 검출하는 제 3감지수단(88); 및Third sensing means (88) for detecting an engine speed of the vehicle; And 상기 차량의 주행속도를 검출하는 제 4감지수단(89);을 더 포함하며,And fourth sensing means (89) for detecting a traveling speed of the vehicle. 상기 제어부(85)는 상기 리프트 실린더(8)의 작동 중 상기 엔진 회전수가 기설정된 기준치보다 작은 경우 및 상기 차량의 주행속도가 기설정된 범위를 벗어나는 경우 중 어느 하나인 경우 상기 제 2유압펌프(62)의 동력전달이 중지되도록 상기 클러치(90)를 제어하는 것을 특징으로 하는 지게차의 유압시스템.The control unit 85 is the second hydraulic pump 62 when the engine rotational speed is less than a predetermined reference value during the operation of the lift cylinder 8 and when the traveling speed of the vehicle is outside the preset range. Hydraulic system of the forklift, characterized in that for controlling the clutch (90) to stop power transmission. 제 1항 또는 제 2항에 있어서, The method according to claim 1 or 2, 상기 차량의 엔진 회전수를 검출하는 제 3감지수단(88); 및Third sensing means (88) for detecting an engine speed of the vehicle; And 상기 차량의 주행속도를 검출하는 제 4감지수단(89);을 더 포함하며,And fourth sensing means (89) for detecting a traveling speed of the vehicle. 상기 제어부(85)는 상기 리프트 실린더(8)의 작동 중 상기 엔진 회전수가 기설정된 기준치보다 작은 경우 및 상기 차량의 주행속도가 기설정된 범위를 벗어나는 경우 중 어느 하나인 경우 상기 제 1 및 제 2유압라인(64, 66)의 합류가 해제되 도록 상기 바이패스 밸브(87)를 제어하는 것을 특징으로 하는 지게차의 유압시스템.The control unit 85 may operate the first and second hydraulic pressures when the engine speed is smaller than a predetermined reference value during operation of the lift cylinder 8, or when the traveling speed of the vehicle is outside of a preset range. Hydraulic system of the forklift, characterized in that for controlling the bypass valve (87) to release the confluence of the line (64, 66).
KR1020060133393A 2006-12-26 2006-12-26 Hydraulic system of forklift truck KR20080059735A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
KR1020060133393A KR20080059735A (en) 2006-12-26 2006-12-26 Hydraulic system of forklift truck
PCT/KR2007/006782 WO2008078941A1 (en) 2006-12-26 2007-12-24 Hydraulic system of forklift truck

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
KR1020060133393A KR20080059735A (en) 2006-12-26 2006-12-26 Hydraulic system of forklift truck

Publications (1)

Publication Number Publication Date
KR20080059735A true KR20080059735A (en) 2008-07-01

Family

ID=39562687

Family Applications (1)

Application Number Title Priority Date Filing Date
KR1020060133393A KR20080059735A (en) 2006-12-26 2006-12-26 Hydraulic system of forklift truck

Country Status (2)

Country Link
KR (1) KR20080059735A (en)
WO (1) WO2008078941A1 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100948664B1 (en) * 2007-12-04 2010-03-18 울산대학교 산학협력단 Hydroststic transmission for multipurpose vehicle
WO2011068338A3 (en) * 2009-12-04 2011-10-20 두산산업차량 주식회사 Freight weight measurement apparatus and method using compensation pressure in accordance with temperature change of hydraulic fluid
CN103291674A (en) * 2013-05-31 2013-09-11 武汉船用机械有限责任公司 Hydraulic lifting control system
KR20130128850A (en) * 2012-05-18 2013-11-27 주식회사 두산 Hydraulic systems of forklift
KR20160079488A (en) * 2014-12-26 2016-07-06 엘에스엠트론 주식회사 Hydraulic System of Transmission for Vehicle

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8347618B2 (en) 2009-05-13 2013-01-08 Deere & Company Dual pump hydraulic system
JP5763317B2 (en) 2010-09-14 2015-08-12 ニチユ三菱フォークリフト株式会社 Industrial vehicle
FR2992043B1 (en) * 2012-06-15 2015-05-01 P T C DEVICE FOR COUPLING HYDRAULIC HYDRAULIC POWER SUPPLY GROUPS, CORRESPONDING COUPLING METHOD, AND VIBRATION SYSTEM COMPRISING SUCH A COUPLING DEVICE
JP5867458B2 (en) 2013-07-05 2016-02-24 株式会社豊田自動織機 Industrial vehicle
IT202100011933A1 (en) * 2021-05-10 2022-11-10 Toyota Mat Handling Manufacturing Italy S P A Industrial trolley with improved control of combined maneuvers

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100203806B1 (en) * 1996-12-31 1999-06-15 추호석 Hydraulic system in a forklift truck
KR19980067345A (en) * 1997-01-31 1998-10-15 이해규 Loader engine pump control system and method
KR200164952Y1 (en) * 1997-12-10 2000-01-15 추호석 Fluid pressure system for forklift trucks
KR200165927Y1 (en) * 1999-07-23 2000-02-15 대진공작주식회사 Apparatus for actuating a hydraulic pump of a snowplow
JP4795682B2 (en) * 2004-12-27 2011-10-19 Ｔｃｍ株式会社 Hydraulic circuit for forklift

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100948664B1 (en) * 2007-12-04 2010-03-18 울산대학교 산학협력단 Hydroststic transmission for multipurpose vehicle
WO2011068338A3 (en) * 2009-12-04 2011-10-20 두산산업차량 주식회사 Freight weight measurement apparatus and method using compensation pressure in accordance with temperature change of hydraulic fluid
KR20130128850A (en) * 2012-05-18 2013-11-27 주식회사 두산 Hydraulic systems of forklift
CN103291674A (en) * 2013-05-31 2013-09-11 武汉船用机械有限责任公司 Hydraulic lifting control system
CN103291674B (en) * 2013-05-31 2015-10-21 武汉船用机械有限责任公司 A kind of hydraulic lifting control system
KR20160079488A (en) * 2014-12-26 2016-07-06 엘에스엠트론 주식회사 Hydraulic System of Transmission for Vehicle

Also Published As

Publication number Publication date
WO2008078941A1 (en) 2008-07-03

Similar Documents

Publication Publication Date Title
KR20080059735A (en) Hydraulic system of forklift truck
JP4588089B2 (en) Fan drive system
US7069674B2 (en) Hydraulic circuit for backhoe
KR100655329B1 (en) Apparatus for limiting drive-speed of engine type forklift truck
JPH09109908A (en) Hydraulic steering system of industrial vehicle
JPH11115780A (en) Displacement control method of steering pump for work vehicle and its device
WO2006006448A1 (en) Hydraulic drive device for working vehicle
JP4389912B2 (en) Hydraulic control device for industrial vehicle
EP1724182B1 (en) Oil pressure supply device for industrial vehicle
KR101343831B1 (en) Hydraulic system of forklift truck
JP5065632B2 (en) Hydraulic control device for industrial vehicle
JP2970364B2 (en) Fluid pressure circuit in cargo handling vehicle
JPH06301Y2 (en) Hydraulic circuit for vehicle-based construction machinery
KR20080035397A (en) Hydraulic system of 3-pump control valve for energy saving
JP4333633B2 (en) Power steering device and hydraulic control device for industrial vehicle
KR100813774B1 (en) Hydraulic pump control system for a small excavator
JP2596107B2 (en) Hydraulic devices in battery-powered industrial vehicles
JP6535871B2 (en) Industrial vehicles
JP3070387B2 (en) Fluid pressure circuit in cargo handling vehicle
JPH033897A (en) Hydraulic device for battery type industrial vehicle
JP3070386B2 (en) Fluid pressure circuit of cargo handling vehicle
JP6999320B2 (en) Excavator
JP2918953B2 (en) Vehicle hydraulic circuit
JP4795682B2 (en) Hydraulic circuit for forklift
JP2008303053A (en) Hydraulic pressure control device for industrial vehicle

Legal Events

Date Code Title Description
A201 Request for examination
E902 Notification of reason for refusal
E601 Decision to refuse application
J201 Request for trial against refusal decision
J501 Disposition of invalidation of trial