KR19980061406U - 2 stage pump flow control device of wheel loader - Google Patents

Abstract

The present invention relates to a two-stage pump flow control device of a wheel loader, and more particularly, a work device system for driving a driving wheel, a work device system for driving a work device such as a bucket, a pour, an engine for supplying driving horsepower, At least one hydraulic pump driven by the engine, a bucket cylinder and a pour cylinder operated by the discharge oil of the hydraulic pump, and a bucket control valve for controlling the discharge flow rate and direction supplied from the hydraulic pump to the bucket cylinder and the pour cylinder. And an unloading control valve, a bucket operating means for controlling the bucket control valve and the boolean control valve by a driver, and a boolean operating means, and unloading the discharge oil of the hydraulic pump according to the operating pressure of the bucket and the boolean into the hydraulic tank. In a two-stage pump flow control device of a wheel loader including an unloading valve, it is installed between the unloading valve and the hydraulic tank. And a switching valve for switching the opening and closing of the unloading valve according to a predetermined electrical signal, and a controller selectively operated by a driver according to a working state to output the electrical signal to the switching valve. It provides a two-stage pump flow control device.

Description

2 stage pump flow control device of wheel loader

The present invention relates to a two-stage pump flow control device of a wheel loader, and more particularly, in a wheel loader driving at least two hydraulic pumps by a single engine driving, one side according to a driver's signal input according to a working condition. It relates to a two-stage pump flow control device of a wheel loader to reduce the power of the engine by converting the hydraulic oil discharged from the hydraulic pump into a no-load state.

The loader, one of the representative construction machines, generally performs loading operations in which loads such as soil and the like are loaded into a bucket and loaded into a nearby dump truck.

As shown in FIG. 1, a pump flow control apparatus applied to a wheel loader according to the related art includes a working system including a plurality of hydraulic pumps 2, 3, and 4 driven by a single engine 1. It is configured to operate a traveling system consisting of a transmission (not shown) and a traveling wheel (5). That is, some of the power of the engine 1 drives the above-described hydraulic pumps 2, 3, and 4 to operate work devices such as pours and buckets, and some of the remaining power is transmitted through the torque converter 6. It is used to operate the driving wheel 5.

Reference numeral 7, 8 denotes a bucket cylinder and a boolean cylinder, which is an actuator for operating the bucket and the boolean, which is a working device, and 9, 10 are installed between the hydraulic pumps 2, 3 and the actuators 7, 8, and the hydraulic pump. A bucket control valve and a boolean control valve are shown for controlling the flow rate and the flow direction from (2, 3) to perform start, stop and direction change of the actuators 7 and 8. The hydraulic pump 4 is a pilot pump for transmitting a signal pressure to the hydraulic circuit, and the bucket cylinder 7 and the pour cylinder 8 described above with the signal pressure of the pilot pump 4 according to an operation signal by the driver. And a bucket operating lever 11 and a boolean operating lever 12 for controlling the distribution and supply thereof.

The pump flow control device of the loader configured as described above has a small flow rate required for the bucket cylinder 7 or the pour cylinder 8 when the work is carried out to dig into the load while the load is loaded and loaded into the dump truck. And the traction to be able to dig the loader forward is very necessary. On the other hand, when the load is carried on the dump truck, etc. after lifting the load, the required flow rate to the work device such as buoy, bucket, rather than the traction force is increased.

In consideration of these working characteristics, when the unloading valve 13 is installed in the discharge flow path of the hydraulic pump 3 and the digging work is performed, the operating pressure of the buoy or the bucket is increased, so the unloading valve ( 13) to open, to unload the hydraulic pump (3) discharge flow rate, and to use the engine (1) power as much as the running system is left to secure the running towing force.

However, in this case, if the weight of the load is heavy, the pressure of the buoy or bucket is increased to increase the flow rate is reduced despite the work to lift and load the load, but the work speed of the work device is slowed down and the work efficiency decreases. You have a problem.

In addition, in the case of lifting and loading the load, the driving towing force is required to be small and the boolean ascending speed is required to be large, but the maximum discharge amount of the hydraulic pumps 2 and 3 for discharging the flow rate supplied to the buoyant side is usually the driving towing force during operation Since it is set in consideration of, the maximum discharge amount during the stacking operation can be increased even though it is used as it is.

Accordingly, an object of the present invention is to provide an optimum engine horsepower distribution according to the working condition of the loader, thereby providing a two-stage pump flow control device of the wheel loader that can significantly improve the working efficiency in actual work. It is.

1 is a hydraulic circuit diagram applied to a pump flow rate control apparatus of a wheel loader according to the prior art,

Figure 2 is a hydraulic circuit diagram of a two-stage pump flow control device of the wheel loader according to an embodiment of the present invention.

* Explanation of symbols used in the main part of the drawing

1: engine 2, 3: hydraulic pump

4: pilot pump 5: driving wheel

7: bucket cylinder 8: pour cylinder

9: bucket control valve 10: pour control valve

11: bucket operation lever 12: boom operation lever

13: unloading valve 14: tank

15, 17, 20: Valve spring 16: Pressure setting valve

18: Euro 19: Solenoid Valve

21: controller

The object of the present invention described above is a driving device for driving a driving wheel, a working device system for driving a working device such as a bucket, a buoy, an engine for supplying driving horsepower, at least one or more hydraulic pumps driven by the engine, A bucket cylinder and a pour cylinder operated by the discharge oil of the hydraulic pump, a bucket control valve and a boolean control valve for controlling the discharge flow rate and direction supplied from the hydraulic pump to the bucket cylinder and the pour cylinder, and the bucket control by the driver. Two-stage pump of the wheel loader including a bucket operating means for controlling the valve and the boolean control valve and the boolean operating means, and an unloading valve for unloading the discharge oil of the hydraulic pump into the hydraulic tank in accordance with the operating pressure of the bucket and the boolean. In the flow control device, the unloading valve is installed between the unloading valve and the hydraulic tank is switched in accordance with a predetermined electrical signal It is achieved by providing a two-stage pump flow control device of the wheel loader, characterized in that it comprises a switching valve for opening and closing the switch and a controller selectively operated by the driver in accordance with the working state to output the electrical signal to the switching valve. do.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Figure 2 is a hydraulic circuit diagram of a two-stage pump flow control device of the wheel loader according to an embodiment of the present invention.

As shown in detail in the drawings, prior to describing an embodiment of the present invention, a traveling system including a engine 1, a driving wheel 5 connected to and driven by the engine 1, and a bucket and a buoy are included. The hydraulic circuit configuration of the basic loader of the work system is substantially the same as the conventional one shown in FIG. 1, and thus a detailed description thereof is omitted, and overlapping reference numerals are denoted the same.

Therefore, according to a preferred embodiment of the present invention, selectively opening and closing the unloading valve 13 for unloading the discharge flow rate of the hydraulic pump 3 described above to the hydraulic tank 14 in accordance with the working conditions of the loader. It is provided with a means.

The above-mentioned unloading valve 13 is installed between the discharge passage of the hydraulic pump 3 and the hydraulic tank 14, and is connected between the hydraulic pump 3 and the hydraulic tank! 4 by the valve spring 15. It is initially set in the state of blocking, and when the operating pressure discharged from the hydraulic pump 2 described above between the hydraulic tank 14 and the unloading valve 13 is equal to or greater than a predetermined set value, it is determined by the operating pressure of the bucket or the buoy. A pressure setting valve 16 is installed to open and unload the unloading valve 13 by switching part of the hydraulic oil discharged from the hydraulic pump 3.

The pressure setting valve 16 described above is initially set in a state in which the unloading valve 13 is closed when the discharge pressure from the hydraulic pump 2 is less than or equal to a predetermined set value by the valve spring 17.

The unshown switch of the controller 21 by the driver according to the working state between the oil passage 18 and the hydraulic tank 14 in which the remaining flow rate at the time of opening the aforementioned unloading valve 13 is discharged to the hydraulic tank 14. The solenoid valve 19 which is switched according to the application of the electrical signal due to the operation is installed, and the aforementioned solenoid valve 19 is opposed to the valve spring 20 even when the discharge pressure from the hydraulic pump 2 is below a predetermined set value. It is installed so as to unload a part of the hydraulic oil selectively opened in accordance with the electrical signal applied to the side and discharged from the hydraulic pump 3.

Referring to the operation of the present invention configured as described above, the bucket cylinder (7) or the boom cylinder (8) is driven by the operating pressure discharged from the hydraulic pump (2 or 3) by driving the engine (1), thereby In the case of digging into the load to excavate the load to the truck, the operating pressure of the buoy or bucket increases because the operating pressure of the bucket cylinder (7) or the buoy cylinder (8) is the valve spring of the pressure setting valve (16). 17) Acting on the opposite side, the inner spline is switched downward in the drawing.

Due to this, the part of the operating pressure discharged from the hydraulic pump 3 is acted on the opposite side of the valve spring 15 of the unloading valve 13 by the orifice 22, the unloading valve 13 is opened, As a part of the hydraulic oil discharged from the hydraulic pump 3 is unloaded through the unloading valve 13, a corresponding torque of the engine 1 is utilized in the traveling system to sufficiently secure the traction force of the equipment. It becomes possible.

Then, when the working state of the equipment is a working state that requires a traction force preferentially rather than a work device driving force, the valve spring 20 of the solenoid valve 19 is opposed due to the switch operation of the controller 21 not shown by the driver. As the electrical signal is applied to the side, the solenoid valve 20 is switched upward in the figure to open the unloading valve 13, whereby a part of the hydraulic oil discharged from the hydraulic pump (3) is unloading valve ( 13 is returned to the tank 14.

Therefore, the engine 1 using torque as much as the discharge flow rate unloaded into the tank 14 can be used in the traveling system so as to sufficiently secure the running towing force of the equipment.

On the other hand, if the working state of the equipment does not require a traction force, the hydraulic pump (3) by blocking the electrical signal applied to the solenoid valve 19 due to the switch operation of the controller 21 described above by the driver. All the hydraulic fluid discharged from the) is supplied to the pour side so that the operating speed of the working device can be sufficiently secured.

As described above, the two-stage pump flow control device of the wheel loader according to the present invention, it is possible to obtain the optimum engine horsepower distribution according to the working condition of the loader using at least one hydraulic pump driven by a single engine Therefore, it is possible to reduce fuel consumption per unit time, reduce heat load, and extend durability life of hydraulic parts, and speed and force in actual work By increasing the number of steps, the work efficiency can be greatly improved (about 20% or more in the same working condition).

Claims (1)

It is operated by a traveling device for driving a driving wheel, a working system for driving a working device such as a bucket and a buoy, an engine for supplying driving horsepower, at least one hydraulic pump driven by the engine, and discharge oil of the hydraulic pump. A bucket cylinder and a boolean cylinder, a bucket control valve and a boolean control valve for controlling the discharge flow rate and direction supplied from the hydraulic pump to the bucket cylinder and the boolean cylinder, and controlling the bucket control valve and the boolean control valve by an operator. In the two-stage pump flow control device of the wheel loader including a bucket operation means and a buoy operation means, and an unloading valve for unloading the discharge oil of the hydraulic pump to the hydraulic tank in accordance with the operating pressure of the bucket and the buoy, A switching valve installed between the unloading valve and the hydraulic tank and switched according to a predetermined electrical signal to open and close the unloading valve; And a controller which is selectively operated by a driver in accordance with a working state and outputs the electrical signal to the switching valve.