KR20230059936A - Hydraulic system for forklift - Google Patents

Abstract

According to the present embodiments, a transmission can be manufactured compactly by simplifying the configuration of a control valve, and it is possible to save manufacturing costs by reducing the number of necessary mechanical valves.

Description

Forklift hydraulic system {HYDRAULIC SYSTEM FOR FORKLIFT}

The present embodiments relate to a hydraulic system of a forklift, and more particularly, to a hydraulic system of a forklift, in which a transmission can be manufactured compactly by simplifying the configuration of a control valve, and manufacturing costs can be saved by reducing the number of mechanical valves required. it's about

A forklift is a vehicle capable of lifting or moving cargo by moving to a loading position and then raising or lowering a fork provided at the front of the vehicle with a work machine.

In general, a forklift implements both driving of a vehicle and operation of a work machine by using a single engine as a power source. Therefore, when the accelerator pedal is pressed to increase the speed of the working machine, the driving speed of the vehicle is increased together.

However, most cases of increasing the speed of the implement are cases of lifting the implement to the cargo to be loaded or lifting the loaded cargo to the target position, and a contradictory situation occurs in which the vehicle is required to move very slowly or stop. .

Therefore, in addition to the accelerator pedal and the brake pedal, the forklift is further provided with an inching pedal, so that when the vehicle is driving, the transmission transmits engine power to the wheels as in a general vehicle, but when the driver steps on the inching pedal while operating the machine, the transmission The hydraulic pressure transmitted to the clutch disk of the is cut off.

Referring to FIG. 1, in the conventional forklift hydraulic system, a control valve for adjusting hydraulic pressure transmitted to a clutch disk includes a relief valve, a modulation valve, and an inching valve, and a valve controlling the operation of the clutch disk is turned on and off. It was a solenoid valve structure. That is, according to gear operation, the on/off solenoid valve is controlled to be on or off, the flow path to the forward or reverse clutch disk is opened or closed, and the hydraulic pressure to the opened clutch disk is controlled by the modulation valve. And, as the driver steps on the inching pedal, the flow paths to the forward clutch disk and the reverse clutch disk are closed by the inching valve.

However, according to the hydraulic system having such a structure, since the control valve includes not only a relief valve but also a modulation valve and an inching valve, the size is excessively increased and a large number of mechanical valves are required, resulting in excessive manufacturing cost.

The present embodiments have been devised from the foregoing background, and relate to a hydraulic system of a forklift, in which a transmission can be manufactured compactly by simplifying the configuration of a control valve, and manufacturing costs can be saved by reducing the number of necessary mechanical valves.

According to the present embodiments, the main pump supplying oil from the tank to the supply line, supplying pressure to the clutch disc and brake disc, and discharging the oil to the tank when the pressure of the supply line exceeds the set pressure A control valve including a relief valve, a proportional control valve for receiving oil from the supply line and controlling the engaged state of the clutch disc, a sensor for detecting the amount of depression of the inching pedal, and proportional to the amount of depression of the inching pedal detected by the sensor A hydraulic system of a forklift truck including an electronic control device for controlling a control valve may be provided.

According to the present embodiments, a transmission can be manufactured compactly by simplifying the configuration of a control valve, and it is possible to save manufacturing costs by reducing the number of necessary mechanical valves.

1 is a circuit diagram of a hydraulic system of a conventional forklift.
2 is a circuit diagram of a hydraulic system of a forklift according to the present embodiments.

DETAILED DESCRIPTION Some embodiments of the present disclosure are described in detail below with reference to exemplary drawings. In adding reference numerals to components of each drawing, the same components may have the same numerals as much as possible even if they are displayed on different drawings. In addition, in describing the present embodiments, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present technical idea, the detailed description may be omitted. When "comprises", "has", "consists of", etc. mentioned in this specification is used, other parts may be added unless "only" is used. In the case where a component is expressed in the singular, it may include the case of including the plural unless otherwise explicitly stated.

Also, terms such as first, second, A, B, (a), and (b) may be used in describing the components of the present disclosure. These terms are only used to distinguish the component from other components, and the nature, sequence, order, or number of the corresponding component is not limited by the term.

In the description of the positional relationship of components, when it is described that two or more components are "connected", "coupled" or "connected", the two or more components are directly "connected", "coupled" or "connected". ", but it will be understood that two or more components and other components may be further "interposed" and "connected", "coupled" or "connected". Here, other components may be included in one or more of two or more components that are “connected”, “coupled” or “connected” to each other.

In the description of the temporal flow relationship related to components, operation methods, production methods, etc., for example, "after", "continued to", "after", "before", etc. Alternatively, when a flow sequence relationship is described, it may also include non-continuous cases unless “immediately” or “directly” is used.

On the other hand, when a numerical value or corresponding information (eg, level, etc.) for a component is mentioned, even if there is no separate explicit description, the numerical value or its corresponding information is not indicated by various factors (eg, process factors, internal or external shocks, noise, etc.) may be interpreted as including an error range that may occur.

2 is a circuit diagram of a hydraulic system of a forklift according to the present embodiments.

The hydraulic system of a forklift according to the present embodiments supplies pressure to a pump that supplies oil from a tank to a supply line, a clutch disc, and a brake disc, and discharges oil to the tank when the pressure of the supply line exceeds the set pressure. A control valve including a main relief valve, a proportional control valve for receiving oil from the supply line and controlling the engaged state of the clutch disc, a sensor for detecting the amount of depression of the inching pedal, and a sensor for detecting the amount of depression of the inching pedal detected by the sensor It includes an electronic control device that controls the proportional control valve.

The oil discharged from the tank by the pump is supplied to the clutch disc through the supply line and proportional control valve. The control valve for controlling the hydraulic pressure supplied to the supply line includes a main relief valve. The main relief valve is opened when the pressure in the supply line exceeds the set pressure, and the oil exceeding the set pressure is discharged into the tank. The oil supplied through the supply line is supplied to the parking line to operate the parking brake of the axle.

The hydraulic pressure of the clutch disc is controlled according to the opening amount of the proportional control valve, and the opening amount of the proportional control valve is performed by an electronic control device. That is, in the conventional forklift hydraulic system, the valve for controlling the operation of the clutch disk is provided as an on-off solenoid valve, and the hydraulic pressure supplied to the on-off solenoid valve is controlled by the modulation valve of the control valve. In the hydraulic system of a forklift, the control valve does not include a modulation valve, and the operation of the clutch disk is controlled by the electronic control device controlling the opening amount of the proportional control valve. Therefore, compared to the conventional hydraulic system, the configuration of the control valve is simplified and the number of required mechanical valves is reduced, thereby saving manufacturing costs.

The clutch disk may include first and second stage clutch disks as well as forward and reverse clutch disks, and a plurality of proportional control valves may be provided to control hydraulic pressure supplied to each clutch disk. Each of the plurality of proportional control valves may be independently controlled by an electronic control device.

In addition, when the driver steps on the inching pedal, the electronic control device controls the opening amount of the proportional control valve according to the depressed amount of the pedal to control the hydraulic pressure of the clutch disc. That is, in the conventional forklift hydraulic system, the control valve includes an inching valve provided on a supply line, and the inching valve is mechanically operated by an inching pedal. It was a structure that controls the hydraulic pressure of the disk. However, in the hydraulic system of the forklift according to the present embodiments, the control valve does not include an inching valve, and when the driver steps on the inching pedal, the electronic control device controls the proportional control valve according to the amount of depression of the inching pedal to supply to the clutch disk. control the hydraulic pressure. Therefore, compared to the conventional hydraulic system, the configuration of the control valve is simplified and the number of required mechanical valves is reduced, thereby saving manufacturing costs.

The hydraulic system of a forklift according to the present embodiments includes a sensor for detecting a depression amount of an inching pedal. The sensor detects the amount of depression when the driver operates the inching pedal, and the electronic controller controls the proportional control valve according to the amount of depression to reduce the hydraulic pressure supplied to the clutch disk. Such a sensor may be, for example, an angle sensor or a stroke sensor.

In addition, when the proportional control valve is opened and closed according to the amount of depression of the inching pedal detected by the sensor according to the present embodiments, the clutch disk hydraulic profile may be configured differently during inching operation according to vehicle characteristics, driving conditions, and the like. That is, according to the conventional forklift hydraulic system, the opening and closing amount of the inching valve is determined according to the operator's inching pedal operation, but according to the present embodiments, the electronic control device adjusts the opening and closing amount of the proportional control valve in response to the depression amount of the inching pedal. It can be determined according to characteristics and driving conditions. The amount of opening and closing of the direct control valve according to the amount of depression of the inching pedal may be set in advance according to the characteristics of the vehicle or the like, or may be adjusted in real time according to the driving condition.

According to the hydraulic system of a forklift having such a structure, a transmission can be manufactured compactly by simplifying the configuration of a control valve, and it is possible to save manufacturing costs by reducing the number of necessary mechanical valves.

The above description is merely illustrative of the technical idea of the present disclosure, and various modifications and variations can be made to those skilled in the art without departing from the essential characteristics of the technical idea. In addition, since the present embodiments are not intended to limit the technical idea of the present disclosure, but to explain, the scope of the present technical idea is not limited by these embodiments. The scope of protection of the present disclosure should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of rights of the present disclosure.

Control Valve: Control valve Main Relief Valve: Main relief valve
Clutch: Clutch

Claims (2)

a pump supplying oil from the tank to the supply line;
a control valve including a main relief valve that supplies pressure to the clutch disc and brake disc and discharges oil to the tank when the pressure in the supply line exceeds the set pressure;
a proportional control valve for receiving oil from the supply line and controlling an engaged state of the clutch disk;
A sensor for detecting the amount of depression of the inching pedal;
an electronic control device for controlling the proportional control valve according to the amount of depression of the inching pedal detected by the sensor;
A forklift hydraulic system comprising a. According to claim 1,
The hydraulic system of a forklift, characterized in that the sensor is an angle sensor or a stroke sensor.

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