KR20150055392A - Hydraulic system applied extra pump and clutch to improve fuel efficiency in forklifts - Google Patents

Hydraulic system applied extra pump and clutch to improve fuel efficiency in forklifts Download PDF

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Publication number
KR20150055392A
KR20150055392A KR1020130137692A KR20130137692A KR20150055392A KR 20150055392 A KR20150055392 A KR 20150055392A KR 1020130137692 A KR1020130137692 A KR 1020130137692A KR 20130137692 A KR20130137692 A KR 20130137692A KR 20150055392 A KR20150055392 A KR 20150055392A
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KR
South Korea
Prior art keywords
power
clutch
unit
lever
hydraulic
Prior art date
Application number
KR1020130137692A
Other languages
Korean (ko)
Inventor
김성철
이재훈
정명길
최세경
Original Assignee
현대중공업 주식회사
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Application filed by 현대중공업 주식회사 filed Critical 현대중공업 주식회사
Priority to KR1020130137692A priority Critical patent/KR20150055392A/en
Publication of KR20150055392A publication Critical patent/KR20150055392A/en

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    • 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
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B23/00—Pumping installations or systems
    • F04B23/04—Combinations of two or more pumps
    • 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
    • F16H2061/0015—Transmission control for optimising fuel consumptions

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  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Structural Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Civil Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • General Engineering & Computer Science (AREA)
  • Forklifts And Lifting Vehicles (AREA)

Abstract

The present invention relates to a hydraulic system for a forklift, and more particularly, to a hydraulic control system for a forklift, comprising: a lever operation detection unit for detecting an operation of a user lever and generating a lever position signal; A control unit for generating a control signal corresponding to a lever operation based on the lever position signal generated by the lever operation sensing unit; A continuously driving pump for supplying hydraulic power to a hydraulic device that receives power generated by the engine and requires constant hydraulic power; A power extracting unit for extracting the power generated by the engine; A conditional drive pump that receives the power extracted by the power extractor and supplies the power to the main control valve; A clutch part connecting or disconnecting the conditional drive pump and the conditional drive pump under the control of the clutch valve part; And a clutch control valve unit for controlling the driving of the clutch unit based on the generated control signal. Therefore, when the user does not operate the lever, unnecessary hydraulic power loss can be prevented and the fuel consumption performance can be improved.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a hydraulic system for a forklift that uses an additional pump and a clutch for improving fuel economy.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic system for a forklift, and more particularly, to a hydraulic system for a forklift which separates a pump for supplying hydraulic pressure to a device requiring constant power in a hydraulic system applying a fixed displacement pump, And a hydraulic system of a forklift capable of improving fuel economy by controlling the hydraulic pressure by a clutch.

Generally, a forklift is used for lifting or lowering a heavy cargo and for transporting the cargo to another place. The front drive wheel and the rear steering wheel drive and corner, and the work function of the forklift is realized by the working device. The work function of the forklift is the lift function to move the cargo up and down with the fork, and the tilt function to adjust the mast vertically connected to the fork to the ground at a certain angle. In addition, the forklift may include some added functions depending on the object to be worked on.

The driver lifts the heavy object with the lift function of the forklift and tilts the mast with the tilt function for safe movement before moving.

A common forklift is equipped with a hydraulic pump and a travel transmission connected in parallel to the output shaft of the engine. Hydraulic pumps for forklifts are generally classified as fixed displacement pumps and variable displacement pumps. Fixed displacement pumps are not adjustable because of the constant discharge rate, but they are low in cost. Variable displacement pumps control the angle of the roof The discharge amount can be adjusted while the cost is high. In the field of forklift trucks, fixed capacity pumps are still widely used in consideration of price competitiveness.

The flow rate discharged from the hydraulic pump is supplied to the steering device, the brake device, and the main control valve, which operate by hydraulic power, and must be always supplied to the steering device and the brake device which require a fast response speed. Accordingly, the hydraulic system includes a hydraulic circuit so that the flow rate can be preferentially supplied to the steering device and the brake device. For example, when the hydraulic system distributes the flow rate to the steering device and the main control valve, the flow rate is preferentially supplied to the steering device by using a priority valve, and the flow rate of the flow pipe toward the steering device If the reference pressure is above a certain pressure, the flow rate can be supplied to the main control valve.

Korean Patent No. 10-1053175 (registered on July 26, 2011) relates to a hydraulic system of a control valve for energy-saving three-pump control, and supplies pressure oil from a hydraulic pump driven by a power source such as an electric motor or an internal combustion engine A main control unit provided on the flow path between the hydraulic pump and the steering unit for operating the steering unit or the lift, tilt, auxiliary device, or the like according to the load pressure of the steering unit, And a priority valve for selectively supplying the main control valve to the main control valve. Here, the primary valve distributes the pressure oil discharged from the hydraulic pump to the main control valve for controlling the working machine such as the lift cylinder, the tilde cylinder, and the auxiliary working device simultaneously with the steering unit. And supplying the pressure oil necessary for the operation to the main control valve after supplying the pressure oil sufficiently.

In the hydraulic system of the forklift using the conventional fixed capacity hydraulic pump as described above, the hydraulic pump receives power from the engine to generate pressure and flow rate, and supplies the flow rate to the steering device, the brake device, and the main control valve at the same time Supply. Here, the steering device and the brake device are always required to supply a flow rate, while the actuators (for example lift cylinders, tilt cylinders) connected to the main control valve-the main control valve- Only the flow supply is necessary.

However, in the conventional hydraulic system, the flow rate was continuously supplied to the main control valve irrespective of the lever operation, and the flow rate was shifted to the hydraulic tank along the return path. That is, when the user does not operate the lever, the circulation of the flow rate discharged from the pump by the power of the engine to the tank continuously means power loss and consequently the efficiency of fuel consumption is also lowered.

Korean Registered Patent No. 10-1053175 (registered on July 26, 2011)

The present invention senses a lift lever and a tilt lever operation signal from a user, and the controller controls a clutch control valve that connects the power transmission device of the engine and the conditional drive pump based on the sensed signal. The clutch connects or disconnects the conditional drive pump to the engine's power take-off device by means of a control valve. The present invention provides a hydraulic system that improves the fuel efficiency of the forklift by reducing the consumable return flow rate by applying a pump operating conditionally by the clutch and the engine.

The hydraulic system of the forklift among the embodiments includes a lever operation detecting unit for detecting an operation of a user lever and generating a lever position signal; A control unit for generating a control signal corresponding to a lever operation of the user based on the lever position signal generated by the lever operation detection unit; A continuously driving pump for supplying hydraulic power to a hydraulic device that receives power generated by the engine and requires constant hydraulic power; A power extracting unit for extracting the power generated by the engine; A conditional drive pump that receives the extracted power and supplies hydraulic power to the main control valve; A clutch unit connecting or disconnecting the conditional drive pump and the power extracting unit according to a clutch control valve; And a clutch control valve unit for controlling the driving of the clutch unit based on the generated control signal.

In one embodiment, the lever operation sensing unit may generate a lever position signal for driving a conditionally required device driven at the time of operation of the user lever and input the lever position signal to the control unit.

In one embodiment, the control unit may determine whether the lever of the user is operated by a lever position signal received from the lever operation sensing unit, and may supply a control signal for controlling the clutch to the clutch control valve unit.

In one embodiment, the clutch control valve unit may control the coupling drive or the discrete drive of the clutch unit according to a control signal received from the control unit rotor.

In one embodiment, the power extracting unit extracts the power generated by the engine, transmits the extracted power connected to the conditional drive pump by the coupling drive of the clutch to the conditional drive pump, or disconnects the clutch It is possible to prevent the extracted power from being separated from the conditional drive pump by the drive and deliver it to the conditional drive pump. Alternatively, the conditional drive pump may be connected to the power extracting unit by coupling drive of the clutch unit to generate hydraulic power and supply the power to the main control valve, or may be separated from the power extracting unit by separation drive of the clutch unit Hydraulic power may not be generated.

The hydraulic system of the forklift according to an embodiment of the present invention includes a clutch, a clutch control valve, a clutch control valve, a clutch control valve, and a clutch control valve for separating the hydraulic pressure supply pump into a constant drive pump and a conditional drive pump, The controller was applied. The conditional drive pump is connected to the power transmission of the engine only when the user operates the lever to supply the flow rate to the work unit so that unnecessary hydraulic power loss is prevented when the user does not operate the lever, can do.

1 is a view for explaining a control system for a forklift according to an embodiment of the present invention.
2 is a view for explaining a power transmission system by the clutch control valve in Fig.
3 is a view illustrating a hydraulic system of a forklift according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

The hydraulic system of a forklift according to an embodiment of the present invention includes a power transmission system for connecting a conditional drive pump to an engine and a control system for controlling the same, . Here, the engine may include a separate power transmission device for supplying power generated from the engine to the outside, in which case "connection to the engine" may be interpreted as "connection to the power transmission device of the engine ". Hereinafter, the control system, the power transmission system, and the hydraulic system will be described in order.

1 is a view for explaining a control system for a forklift according to an embodiment of the present invention.

Referring to FIG. 1, a control system 100 of a forklift includes a lever operation sensing unit 110, a control unit 120, and a clutch control valve unit 130.

The lever operation sensing unit 110 senses the operation of the user lever and generates a lever position signal. That is, the lever operation sensing unit 110 generates a lever position signal when the user operates the lever, and provides the generated lever position signal to the control unit 120. The control unit 120 generates a control signal corresponding to the lever operation of the user based on the lever position signal generated by the lever operation sensing unit 110. [

More specifically, a lever position signal input from the lever operation sensing unit 110 is checked, and a control signal for controlling the operation of the clutch control valve unit 130 is generated correspondingly. Then, And supplies it to the control valve unit 130. For example, the control unit 120 may be implemented as an MCU (Machine Control Unit).

The clutch control valve unit 130 controls driving of the clutch unit, which will be described later, based on the control signal generated by the control unit 120. [

More specifically, the clutch control valve unit 130 receives a control signal from the control unit 120 and controls to connect or disconnect the engine and the conditional drive pump through a clutch (not shown) to be described later. Here, the power transmission system for connecting or disconnecting between the engine and the conditional drive pump will be described later with reference to Fig.

In one embodiment, the clutch control valve portion 130 may be implemented in the form of a solenoid valve or an electronic proportional pressure control valve.

The control unit 120 controls the clutch control valve unit 130 so that when the lever operation of the user is detected based on the lever position signal provided from the lever operation sensing unit 110, Connection control signal). That is, the control system 100 of the forklift can connect the engine and the conditional drive pump through the clutch based on the control signal, and supply the flow rate to the main control valve.

In another embodiment, the control unit 120 controls the clutch control valve unit 130 so as to shut off the flow rate supplied to the main control valve when the lever operation of the user is not detected, Signal). That is, the control system 100 of the forklift can separate the engine and the conditional drive pump based on the control signal, and can not supply the flow rate to the main control valve (or shut off the flow rate supply).

Fig. 2 is a view for explaining a power transmission system operated by the clutch control valve portion shown in Fig. 1. Fig.

Referring to FIG. 2, the power transmission system 200 includes a constant drive pump 210, a power extractor 220, a conditional drive pump 230, and a clutch 240. Here, the clutch portion 240 is operated by the clutch control valve portion 130.

The normally-driven pump 210 corresponds to a hydraulic pressure supply pump connected to the hydraulic device side which always requires a flow rate, and receives the power generated by the engine to generate pressure and flow rate. Here, the hydraulic device that requires a constant flow rate corresponds to a traveling device of the forklift, and may include at least one of, for example, a steering device and a brake device.

The power extracting unit 220 separately extracts the power generated by the engine through a mechanical connection line.

The conditional drive pump 230 corresponds to a hydraulic pressure supply pump connected to the main control valve side and is connected to the power extracting unit 220 via a clutch unit 240 to be described later to receive the extracted power to generate a pressure and a flow rate do. The conditional drive pump 230 can supply the generated flow rate to the main control valve.

Here, the main control valve corresponds to a valve that controls the operation of the hydraulic device that requires a flow rate supply in accordance with the lever operation of the user. Further, the hydraulic device which requires the supply of the flow rate in accordance with the lever operation corresponds to the working device of the forklift and includes at least one of a cylinder (lift cylinder) for driving the lift and a cylinder (tilt cylinder) for driving the tilt can do.

When the power extracting unit 220 and the conditional drive pump 230 are separated from each other through the clutch unit 240 to be described later, the conditional drive pump 230 can not generate the flow rate, Can not supply.

The clutch unit 240 may be configured to couple the conditional drive pump 230 to the power take-off unit 220 according to the drive control of the clutch control valve unit 130 Disconnects, i.e., disconnects, the connection between the extractor 220 and the conditional drive pump 230.

3 is a view illustrating a structure of a hydraulic system of a forklift according to an embodiment of the present invention.

3, the hydraulic system 300 of the forklift includes a lever operation sensing unit 310, a control unit 320, a clutch control valve unit 330, a power transmission system 340, an engine 350, A torque converter 360, a transmission 370, a steering device 380, a brake device 390, and a main control valve 410.

Here, the power transmission system 340 includes the constant drive pump 341, the power extracting portion 342, the conditional drive pump 343, and the clutch portion 344, as described with reference to FIG. 3, the engine 350 and the always-on drive pump 341 are connected through a mechanical line for power transmission. Similarly, the engine 350 and the power extractor 342, the engine 350 and the torque converter 360, the transmission 370 and the drive axle (not shown) are also connected through a machine line.

The normally driven pump 341 and the steering device 380 are connected via a hydraulic line for supplying the flow rate. The main control valve 410 and the lift cylinder 420, the main control valve 410, and the main control valve 410, The tilt cylinder 430 is also connected via a hydraulic line.

The lever operation detection unit 310 and the control unit 320 are connected to each other through an electric line for transferring electrical signals and are similarly connected to the control unit 320 and the clutch control valve unit 330, 330 and the clutch portion 344 are also connected via an electric line, respectively.

The hydraulic system 300 of the forklift has a structure in which the power of the engine 350 is branched through the machine line to the power transmission system 340 and the transmission 370, respectively.

A power extracting section 342 for extracting the power of the engine 350 is further provided in order to improve the fuel consumption in the case of using the constant drive pump 341 of the power transmission system 340, The flow rate to the main control valve 410 side only at the time of the lever operation of the user, separately from the steady drive pump 341 for advanced flow rate, to the steering device 380 and the brake device 390, The conditional drive pump 343 is connected to or disconnected from the power extracting portion 342 by using the clutch portion 344 so that the power can be supplied. At this time, the clutch unit 344 is controlled by the control unit 320 and the clutch control valve unit 330 according to the input of the lever position signal that senses the operation of the user lever, and the conditional drive pump 343 is connected to the power extracting unit 342, or separates the power extracting section 342 and the conditional drive pump 343 from each other.

Accordingly, the hydraulic system 300 of the forklift connects the conditional drive pump 343 to the engine 350 only when the user operates the lever, and supplies the flow rate to the work device. If the user does not operate the lever The supply of hydraulic pressure to the conditional drive pump 343 is interrupted to prevent unnecessary loss of hydraulic power and improve the fuel efficiency.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the present invention as defined by the following claims It can be understood that

100: Control system of forklift
110, 310: a lever operation detecting unit
120, 320:
130, 330: clutch control valve unit
200, 340: Power transmission system
210, 341:
220, 342:
230, 343: Conditional drive pump
240, 344:
350: engine
360: torque converter
370: Transmission
380: Steering device
390: Brake device
410: main control valve
420: lift cylinder
430: Tilt cylinder

Claims (6)

A lever operation detecting unit for detecting an operation of the user lever and generating a lever position signal;
A control unit for generating a control signal corresponding to a lever operation of the user based on the lever position signal generated by the lever operation detection unit;
A continuously driving pump for supplying hydraulic power to a hydraulic device that receives power generated by the engine and requires constant hydraulic power;
A power extracting unit for extracting the power generated by the engine;
A conditional drive pump that receives the extracted power and supplies hydraulic power to the main control valve;
A clutch unit connecting or disconnecting the conditional drive pump and the power extracting unit according to a clutch control valve; And
And a clutch control valve portion for controlling the drive of the clutch portion based on the generated control signal.
The apparatus according to claim 1, wherein the lever operation detecting unit
A lever position signal for driving a conditionally required device driven at the time of operation of the user lever is generated and inputted to the control unit.
The apparatus of claim 1, wherein the control unit
And a control signal for controlling the clutch is supplied to the clutch control valve unit by determining whether or not the lever of the user is operated by the lever position signal received from the lever operation detection unit.
4. The clutch control device according to claim 3,
Wherein the control unit controls the connection or disconnection of the clutch unit according to a control signal received from the control unit rotor.
The power control apparatus according to claim 4,
And a control unit that extracts the power generated by the engine and transmits the extracted power connected to the conditional drive pump by the coupling drive of the clutch unit to the conditional drive pump, And does not transmit the extracted power to the conditional drive pump.
5. The apparatus according to claim 4,
And is connected to the power extracting portion by the coupling drive of the clutch portion to generate hydraulic power to supply the hydraulic power to the main control valve or to separate from the power extracting portion by the separation drive of the clutch portion, Hydraulic system of forklift.

KR1020130137692A 2013-11-13 2013-11-13 Hydraulic system applied extra pump and clutch to improve fuel efficiency in forklifts KR20150055392A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
KR1020130137692A KR20150055392A (en) 2013-11-13 2013-11-13 Hydraulic system applied extra pump and clutch to improve fuel efficiency in forklifts

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
KR1020130137692A KR20150055392A (en) 2013-11-13 2013-11-13 Hydraulic system applied extra pump and clutch to improve fuel efficiency in forklifts

Publications (1)

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KR20150055392A true KR20150055392A (en) 2015-05-21

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