WO2017018557A1

WO2017018557A1 - Hydraulic circuit for construction machine

Info

Publication number: WO2017018557A1
Application number: PCT/KR2015/007867
Authority: WO
Inventors: 김진욱; 강민혁
Original assignee: 볼보 컨스트럭션 이큅먼트 에이비; 김진욱
Priority date: 2015-07-28
Filing date: 2015-07-28
Publication date: 2017-02-02

Abstract

Disclosed is a hydraulic circuit for controlling operation oil, which is supplied from a hydraulic pump to a hydraulic cylinder, and operation oil, which is returned from the hydraulic cylinder to an operation oil tank. The present invention provides a hydraulic circuit for a construction machine, characterized by comprising: a hydraulic pump and a pilot pump; a hydraulic cylinder driven by operation oil from the hydraulic pump; an electrically manipulated level; a first control valve installed in a channel between the hydraulic pump and the hydraulic cylinder so as to supply, when switching, operation oil from the hydraulic pump to a first chamber of the hydraulic cylinder or to return operation oil, which is discharged from the first chamber of the hydraulic cylinder, to an operation oil tank; a second control valve installed in a channel between the hydraulic pump and the hydraulic cylinder so as to return, when switching simultaneously with the first control valve, operation oil, which is discharged from a second chamber of the hydraulic cylinder, to the operation oil tank or to supply operation oil from the hydraulic pump to the second chamber of the hydraulic cylinder; and proportional control valves installed in a channel between the pilot pump and the first control valve and in a channel between the pilot pump and the second control valve, respectively, such that, in order to independently control the spool opening area of the first and second control valves, a pilot pressure corresponding to the amount of manipulation of the electronically manipulated level is applied to the first and second control valves, thereby switching the same.

Description

Hydraulic Circuit for Construction Machinery

The present invention relates to a hydraulic circuit, and more specifically, to a hydraulic circuit for construction machinery for controlling the hydraulic oil supplied from the hydraulic pump to the hydraulic cylinder and the hydraulic oil returned from the hydraulic cylinder to the hydraulic oil tank.

1 is a hydraulic circuit diagram for a construction machine according to the prior art.

As shown in FIG. 1, a variable displacement hydraulic pump (hereinafter referred to as a hydraulic pump) 1 and a pilot pump 2 are connected to an engine (not shown).

A hydraulic cylinder 3 driven by hydraulic oil supplied from the hydraulic pump 1 is connected to the hydraulic pump 1.

The control valve (MCV) (4) for supplying the hydraulic oil of the hydraulic pump (1) to the hydraulic cylinder (3) or the hydraulic oil discharged from the hydraulic cylinder (3) to the hydraulic oil tank (T) at the time of switching It is installed in the flow path between the hydraulic pump 1 and the hydraulic cylinder (3).

An operation lever RCV (not shown) for outputting a pilot pressure corresponding to the operation amount is provided in a flow path between the pilot pump 2 and the control valve 4.

According to the above-described configuration, when the pilot pressure Pa, which operates the operating lever and converts the hydraulic oil supplied from the pilot pump 2 to correspond to the operation amount, is applied to the left signal pressure port of the control valve 4. The spool of the control valve 4 is switched to the right direction in the drawing.

Therefore, the hydraulic oil of the hydraulic pump 1 passes through the spool of the control valve 4 and is supplied to the first chamber 3a of the hydraulic cylinder 3, and the second chamber 3b of the hydraulic cylinder 3 is provided. The hydraulic oil discharged from) passes through the spool of the control valve 4 and is returned to the hydraulic oil tank (T). Therefore, the hydraulic cylinder 3 can be extended and driven.

On the contrary, when the operation lever is operated, the pilot pressure Pb supplied from the pilot pump 2 and converted to correspond to the operation amount is applied to the right signal pressure port of the control valve 4. The spool of is switched to the left in the figure.

Therefore, the hydraulic oil of the hydraulic pump 1 passes through the spool of the control valve 4 and is supplied to the second chamber 3b of the hydraulic cylinder 3, and the first chamber 3a of the hydraulic cylinder 1 is supplied. The hydraulic oil discharged from) passes through the spool of the control valve 4 and is returned to the hydraulic oil tank (T). Therefore, it is possible to shrink-drive the hydraulic cylinder 3.

At this time, the hydraulic oil supplied from the hydraulic pump 1 to the hydraulic cylinder 3 by the operation of the operation lever, and the amount of hydraulic oil discharged from the hydraulic cylinder 3 and returned to the hydraulic oil tank T is It is determined according to the opening area of the spool of the control valve 4 switched corresponding to the operation amount of the operation lever.

The notch for supplying the hydraulic oil of the hydraulic pump 1 to the hydraulic cylinder 3 and the notch for returning the hydraulic oil discharged from the hydraulic cylinder 3 to the hydraulic oil tank T are the control valves. It is because it forms in two places in the spool of (4).

For this reason, the hydraulic oil of the hydraulic pump 1 is supplied to the hydraulic cylinder 3 according to the pressure generated in the hydraulic cylinder 3 or the movement of the equipment while the hydraulic cylinder 3 is extended or driven. Independent control of the spool opening area of the control valve (4) for supply to the control valve and the spool opening area of the control valve (4) for returning the hydraulic oil discharged from the hydraulic cylinder (3) to the hydraulic oil tank (T) You will not be able to.

That is, the opening area of the spool of the control valve 4 for supplying the hydraulic oil of the hydraulic pump 1 to the hydraulic cylinder 3, and the hydraulic oil discharged from the hydraulic cylinder 3 to the hydraulic oil tank (T). This is because the opening area of the spool of the control valve 4 for returning to the valve is controlled dependently by the pilot pressure applied to the control valve 4 by the operation of the operation lever.

Accordingly, the present invention is to solve the above-mentioned problems, dualizing the control valve for supplying the hydraulic oil of the hydraulic pump to the hydraulic cylinder or the hydraulic oil discharged from the hydraulic cylinder to the hydraulic oil tank in accordance with the pressure generated in the hydraulic cylinder It is an object of the present invention to provide a hydraulic circuit for construction machinery that can be controlled independently.

According to an embodiment of the present invention to achieve the above and other objects of the present invention, a variable displacement hydraulic pump and a pilot pump;

A hydraulic cylinder driven by the hydraulic oil supplied from the hydraulic pump;

An electric operation lever for outputting an electric signal corresponding to the operation amount;

Is installed in the flow path between the hydraulic pump and the hydraulic cylinder, supplying the hydraulic oil of the hydraulic pump to the first chamber of the hydraulic cylinder during switching, or the hydraulic oil discharged from the first chamber of the hydraulic cylinder to the hydraulic oil tank 1 control valve;

Is installed in the flow path between the hydraulic pump and the hydraulic cylinder, the hydraulic oil discharged from the second chamber of the hydraulic cylinder when switching at the same time with the first control valve to return to the hydraulic oil tank, or the hydraulic oil of the hydraulic pump to the hydraulic cylinder A second control valve supplied to a second chamber of the second control valve;

It is installed in the flow path between the pilot pump and the first control valve and the flow path between the pilot pump and the second control valve, to independently control the spool opening area of the first control valve and the second control valve Provided is a hydraulic circuit for a construction machine, characterized in that it comprises a proportional control valve for switching by applying a pilot pressure corresponding to the operation amount of the electric operation lever to the first control valve and the second control valve.

According to the present invention having the above-described configuration, during the operation of driving the hydraulic cylinder, supplying the hydraulic oil of the hydraulic pump to the hydraulic cylinder in accordance with the pressure generated in the hydraulic cylinder, or to control the hydraulic oil returned from the hydraulic cylinder to the hydraulic oil tank By independently controlling the control valve for the dual, it is possible to prevent excessive pressure rise in the hydraulic cylinder, it is possible to increase the working speed by adjusting the operating flow rate supplied to the hydraulic cylinder.

1 is a hydraulic circuit diagram for a construction machine according to the prior art,

2 is a hydraulic circuit diagram for a construction machine according to a preferred embodiment of the present invention.

10; Variable displacement hydraulic pump

11; Pilot pump

12; Hydraulic cylinder

13; Electric control lever (RCV)

14; First Control Valve (MCV)

15; Second control valve (MCV)

16; Proportional control valve (PPRV)

17; First proportional control valve

18; 2nd proportional control valve

19; Third proportional control valve

20; Fourth proportional control valve

Hereinafter, a hydraulic circuit for a construction machine according to a preferred embodiment of the present invention with reference to the accompanying drawings will be described in detail.

2, the hydraulic circuit for a construction machine according to an embodiment of the present invention,

A variable displacement hydraulic pump (hereinafter referred to as a hydraulic pump) 10 and a pilot pump 11 are connected to the engine (not shown).

The hydraulic cylinder 12 driven by the hydraulic oil supplied from the hydraulic pump 10 is connected to the hydraulic pump 10.

When switching by the pilot pressure applied by the operation of the electric control lever (RCV) 13, supply the hydraulic oil of the hydraulic pump 10 to the first chamber 12a of the hydraulic cylinder 12, or the hydraulic pressure A first control valve (MCV) 14 for returning the hydraulic oil discharged from the first chamber 12a of the cylinder 12 to the hydraulic oil tank T is a flow path between the hydraulic pump 10 and the hydraulic cylinder 12. Is installed on.

The hydraulic oil discharged from the second chamber 12b of the hydraulic cylinder 12 when the hydraulic pressure switch 12 is simultaneously switched with the first control valve 14 by the pilot pressure applied by the operation of the electric operation lever 13. The second control valve (MCV) 15 for returning to (T) or supplying the hydraulic oil of the hydraulic pump 10 to the second chamber 12b of the hydraulic cylinder 12 is the hydraulic pump 10 And a flow path between the hydraulic cylinder 12.

In order to independently control the spool opening area of the first control valve 14 and the second control valve 15, the hydraulic oil supplied from the pilot pump 11 is transferred to the electric control lever 13. The pilot pump has a proportional control valve 16 that converts the secondary pilot pressure to correspond to the manipulated variable and applies the secondary pilot pressure to the first control valve 14 and the second control valve 15 to switch the pilot pressure. (11) and the flow path between the first control valve 14 and the flow path between the pilot pump 11 and the second control valve (15).

The proportional pilot reducing valve (PPRV) 16,

When the hydraulic oil of the hydraulic pump 10 is supplied to the first chamber 12a of the hydraulic cylinder 12, it is supplied from the pilot pump 11 to control the spool opening area of the first control valve 14. A first proportional to convert the hydraulic oil to the secondary pilot pressure corresponding to the operation amount of the electric control lever 13, and to switch by applying the converted secondary pilot pressure to the signal pressure port of the first control valve 14; Control valve 17;

When the hydraulic oil discharged from the second chamber 12b of the hydraulic cylinder 12 is returned to the hydraulic oil tank T, the pilot pump 11 to control the spool opening area of the second control valve 15. ) To convert the hydraulic oil supplied from the hydraulic pressure to the secondary pilot pressure corresponding to the operation amount of the electric control lever 13, and to switch by applying the converted secondary pilot pressure to the signal pressure port of the second control valve (15) A second proportional control valve 18;

When the hydraulic oil of the hydraulic pump 10 is supplied to the second chamber 12b of the hydraulic cylinder 12, it is supplied from the pilot pump 11 to control the spool opening area of the second control valve 15. A third proportion of converting the hydraulic fluid to the secondary pilot pressure corresponding to the operation amount of the electric control lever 13 and applying the converted secondary pilot pressure to the signal pressure port of the second control valve 15 for switching. Control valve 19;

When the hydraulic oil discharged from the first chamber 12a of the hydraulic cylinder 12 is returned to the hydraulic oil tank T, the pilot pump 11 to control the spool opening area of the first control valve 14. ) To convert the hydraulic oil supplied from the hydraulic pressure to the secondary pilot pressure corresponding to the operation amount of the electric control lever 13, and to switch by applying the converted secondary pilot pressure to the signal pressure port of the first control valve (14) And a fourth proportional control valve 20.

The first and second proportional control valves 17 and 18 and the third and fourth

proportional control valves

19 and 20 provide electrical signals generated by manipulation of the electric control lever 13. When not applied to the

proportional control valves

17, 18, 19 and 20, the initial operation of blocking the hydraulic oil supplied from the pilot pump 11 from being applied to the first and

second control valves

14 and 15 at the pilot pressure. Maintain state.

The hydraulic cylinder 12 is any one of the boom cylinder, the arm cylinder and the bucket cylinder of the excavator.

Although not shown in the drawing, the opening area of the spool of the first control valve 14 and the second control valve 15 is adjusted according to the magnitude of the pressure generated in the hydraulic cylinder 12 or the machine motion. In order to be able to be, the flow path between the first control valve 14 and the hydraulic cylinder 12 and the flow path between the second control valve 15 and the hydraulic cylinder 12 is installed in the first It may be provided with a pressure sensor for detecting the pressure generated in the first chamber (12a) and the second chamber (12b).

According to the above-described configuration, the extension drive of the hydraulic cylinder 12 will be described first.

The electrical signal resulting from operating the electric control lever 13 to drive the hydraulic cylinder 12 in an extension drive (for example, driving a boom up of an excavator) is the first proportional control valve 17. ) And the second proportional control valve 18 are applied simultaneously.

Therefore, when the electric signal by the operation of the electric operation lever 13 is applied to the first proportional control valve 17, the operating amount of the electric operation lever 13 is supplied with the hydraulic oil supplied from the pilot pump 11. The secondary pilot pressure is converted to the secondary pilot pressure so that the secondary pilot pressure is converted to the right signal pressure port of the first control valve 14.

Since the spool of the first control valve 14 is switched in the left direction in the drawing, the hydraulic oil of the hydraulic pump 10 passes through the spool of the first control valve 14 and thus the first of the hydraulic cylinder 12. It is supplied to the chamber 12a.

On the other hand, when the electric signal by the operation of the electric operation lever 13 is applied to the second proportional control valve 18, the hydraulic oil supplied from the pilot pump 11 the operation amount of the electric operation lever 13 The secondary pilot pressure is converted to the secondary pilot pressure so that the secondary pilot pressure is converted to the left signal pressure port of the second control valve 15.

Since the spool of the second control valve 15 is switched in the right direction in the drawing, the hydraulic oil discharged from the second chamber 12b of the hydraulic cylinder 12 passes through the spool of the second control valve 15. It returns to the said hydraulic oil tank (T).

Therefore, the hydraulic cylinder 12 can be extended and driven.

Hereinafter, the shrinkage driving of the hydraulic cylinder 12 will be described.

The electrical signal generated by operating the electric control lever 13 to contract the hydraulic cylinder 12 (for example, to drive the boom down of the excavator) is the third proportional control valve 19. ) And the fourth proportional control valve 20 are applied simultaneously.

Therefore, when the electric signal by the operation of the electric operation lever 13 is applied to the third proportional control valve 19, the operating amount of the electric operation lever 13 to the hydraulic oil supplied from the pilot pump (11). The secondary pilot pressure is converted to the secondary pilot pressure so as to correspond to the secondary pilot pressure and applied to the right signal pressure port of the second control valve 15.

Since the spool of the second control valve 15 is switched in the left direction in the drawing, the hydraulic oil of the hydraulic pump 10 passes through the spool of the second control valve 15 so that the second of the hydraulic cylinder 12 It is supplied to the chamber 12b.

On the other hand, when the electric signal by the operation of the electric operation lever 13 is applied to the fourth proportional control valve 20, the operating amount of the electric operation lever 13 to the hydraulic oil supplied from the pilot pump 11 The secondary pilot pressure is converted to the secondary pilot pressure so that the secondary pilot pressure is converted to the left signal pressure port of the first control valve 14.

Since the spool of the first control valve 14 is switched to the right in the drawing, the hydraulic oil discharged from the first chamber 12a of the hydraulic cylinder 12 passes through the spool of the first control valve 14. It returns to the said hydraulic oil tank (T).

Therefore, it is possible to shrink-drive the hydraulic cylinder 12.

As described above, the electric control lever 13 is operated to switch the first and

second control valves

14 and 15 by switching the first and second proportional control valves 17 and 18 so that the hydraulic cylinder ( 12) or the first and

second control valves

14 and 15 by switching between the third and fourth

proportional control valves

19 and 20 by operating the electric operation lever 13. The hydraulic cylinder 12 can be driven to shrink.

At this time, the pressure or movement of the equipment generated by the hydraulic cylinder 12 detected by a pressure sensor (not shown) installed in the flow path between the first and

second control valves

14 and 15 and the hydraulic cylinder 12. As a result, the spool opening areas of the first and

second control valves

14 and 15 can be controlled independently.

That is, as the pressure detection signal generated on the first and

second chambers

12a and 12b of the hydraulic cylinder 12 by the pressure sensor is input to the control unit ECU not shown, the electric operation is performed by the control unit. By operating the lever 13, the electrical signals applied to the first and second proportional control valves 17 and 18 or the third and fourth

proportional control valves

19 and 20 are adjusted.

Therefore, the first, second, third, and fourth

proportional control valves

17, 18, 19, and 20 are controlled by controlling the electrical signals applied to the first, second, third, and fourth proportional control valves 13. The magnitude of the pilot pressure applied to the first and

second control valves

14 and 15 may be adjusted in the 3, 4

proportional control valves

17, 18, 19, and 20. Therefore, the opening area of the spool of the first and

second control valves

14 and 15 can be controlled independently.

That is, the first and

second control valves

14 and 15 are switched by the operation of the electric operation lever 13 to supply the hydraulic oil of the hydraulic pump 10 to the hydraulic cylinder 12 and the hydraulic cylinder ( When the hydraulic oil discharged from the 12 is returned to the hydraulic oil tank T, the first and second control valves by the operation of the electric operation lever 13 according to the pressure generated in the hydraulic cylinder 12 ( The spool opening area of 14, 15 can be controlled differently.

Therefore, when the hydraulic cylinder 12 is extended or driven, the hydraulic fluid is supplied from the hydraulic pump 10 to the hydraulic cylinder 12, and the hydraulic oil tank T from the hydraulic cylinder 12. It is possible to control the operating flow rate returned to) differently.

Therefore, according to the hydraulic circuit of the construction machine according to the embodiment of the present invention, the electric signal by the operation of the electric operation lever 13 is simultaneously applied to the first and second proportional control valves 17 and 18 so that the first As the two

control valves

14 and 15 are switched, the hydraulic oil of the hydraulic pump 10 passes through the first control valve 14 to be supplied to the first chamber 12a of the hydraulic cylinder 12. The hydraulic oil discharged from the second chamber 12b of the hydraulic cylinder 12 may be returned to the hydraulic oil tank T. Therefore, the hydraulic cylinder 12 can be extended and driven.

On the contrary, the first and

second control valves

14 and 15 are switched by simultaneously applying electric signals generated by the operation of the electric control lever 13 to the third and fourth

proportional control valves

19 and 20. Accordingly, the hydraulic oil of the hydraulic pump 10 passes through the second control valve 15 to be supplied to the second chamber 12b of the hydraulic cylinder 12, and the first chamber 12a of the hydraulic cylinder 12 is provided. The hydraulic oil discharged from the tank can be returned to the hydraulic oil tank (T). Therefore, the hydraulic cylinder 12 can be driven to shrink.

At this time, according to the magnitude of the pressure generated in the hydraulic cylinder 12, by the operation of the electric control lever 13 to the first, second, third, fourth proportional control valve (17, 18, 19, 20) When adjusting the applied electrical signal, the spool of the first, second control valve 14, which is switched by the pilot pressure applied from the first, second, third, fourth

proportional control valve

17, 18, 19, 20 The opening area can be controlled independently.

That is, in the conventional hydraulic circuit as shown in FIG. 1, the hydraulic cylinder 3 is supplied from the hydraulic pump 1 to the hydraulic cylinder 3 by spool switching of one control valve 4 (MCV) during expansion and contraction operation of the hydraulic cylinder 3. In order to adjust the working oil flow rate and the working oil flow rate returned from the hydraulic cylinder (3) to the hydraulic oil tank (T), various priority valves or flow control valves on the main control valve (MCV) and the boom down side Booster valves are installed.

On the other hand, in the hydraulic circuit of the present invention shown in FIG. 2 from the hydraulic pump 10 by spool switching of the first and

second control valves

14 and 15 independently controlled during expansion and contraction of the hydraulic cylinder 12. The hydraulic fluid supplied to the hydraulic cylinder 12 and the hydraulic fluid returned from the hydraulic cylinder 12 to the hydraulic oil tank T can be controlled differently.

On the other hand, equipment to which an electromagnetic hydraulic valve system (not shown) equipped with an independent metering valve (IMV) is applied is provided with a proportional valve installed on top of a poppet installed in a supply passage of a hydraulic pump. By controlling the control of the movement of the poppet can control the flow rate supplied from the hydraulic pump to the hydraulic cylinder. The electrohydraulic valve system has a disadvantage in that wear occurs in the seat of the poppet due to the impact of the opening / closing cycle. In addition, since the control performance of the poppet decreases due to the wear of the seat, the state of mounting the poppet alone and the performance of the electrohydraulic valve system combining the poppet and the electromagnetic proportional valve are different, thereby making it necessary to modify the electrohydraulic valve system.

On the other hand, in the hydraulic circuit of the present invention, leakage of oil due to abrasion generated on the seat of the poppet and the performance of the electrohydraulic valve system generated by combining the poppet and the electromagnetic proportional valve do not occur.

Herein, while the present invention has been described with reference to the preferred embodiments, those skilled in the art will variously modify the present invention without departing from the spirit and scope of the invention as set forth in the claims below. And can be changed.

According to the present invention having the above-described configuration, the effect that can be independently controlled by dualizing the control valve for controlling the hydraulic oil supplied from the hydraulic pump of the construction machine such as an excavator to the hydraulic cylinder and the hydraulic oil returned from the hydraulic cylinder to the hydraulic oil tank There is.

Claims

Variable displacement hydraulic pump and pilot pump;

A hydraulic cylinder driven by the hydraulic oil supplied from the hydraulic pump;

An electric operation lever for outputting an electric signal corresponding to the operation amount;

Is installed in the flow path between the hydraulic pump and the hydraulic cylinder, supplying the hydraulic oil of the hydraulic pump to the first chamber of the hydraulic cylinder during switching, or the hydraulic oil discharged from the first chamber of the hydraulic cylinder to the hydraulic oil tank 1 control valve;

Is installed in the flow path between the hydraulic pump and the hydraulic cylinder, the hydraulic oil discharged from the second chamber of the hydraulic cylinder when switching at the same time with the first control valve to return to the hydraulic oil tank, or the hydraulic oil of the hydraulic pump to the hydraulic cylinder A second control valve supplied to a second chamber of the second control valve;

It is installed in the flow path between the pilot pump and the first control valve and the flow path between the pilot pump and the second control valve, to independently control the spool opening area of the first control valve and the second control valve And a proportional control valve for switching the pilot pressure corresponding to the operation amount of the electric operation lever to the first control valve and the second control valve.
According to claim 1, wherein the proportional control valve,

When the hydraulic oil of the hydraulic pump is supplied to the first chamber of the hydraulic cylinder, the hydraulic oil supplied from the pilot pump to control the spool opening area of the first control valve corresponds to the operation amount of the electric operation lever. A first proportional control valve that converts the pressure into a pressure and applies the second pilot pressure to the first control valve to switch the pressure;

When the hydraulic oil discharged from the second chamber of the hydraulic cylinder is returned to the hydraulic oil tank, the hydraulic oil supplied from the pilot pump to control the spool opening area of the second control valve corresponds to the operation amount of the electric operation lever. A second proportional control valve converting the secondary pilot pressure and applying the converted secondary pilot pressure to the second control valve to switch the secondary pilot pressure;

When the hydraulic oil of the hydraulic pump is supplied to the second chamber of the hydraulic cylinder, the hydraulic pilot oil supplied from the pilot pump to control the spool opening area of the second control valve corresponds to the operation amount of the electric operation lever. A third proportional control valve that converts the pressure into a pressure and applies the second pilot pressure to the second control valve to switch the pressure;

When the hydraulic oil discharged from the first chamber of the hydraulic cylinder is returned to the hydraulic oil tank, the hydraulic oil supplied from the pilot pump to control the spool opening area of the first control valve corresponds to the operation amount of the electric operation lever. And a fourth proportional control valve which converts the secondary pilot pressure and applies the secondary pilot pressure to the first control valve to switch the secondary pilot pressure.
The method of claim 1, wherein the hydraulic cylinder

Hydraulic circuit for a construction machine, characterized in that any one of the boom cylinder, arm cylinder and bucket cylinder of the excavator.
The method of claim 1,

The spool opening areas of the first control valve and the second control valve are installed in a flow path between the first and second control valves and the hydraulic cylinder to be adjusted according to the magnitude of the pressure generated in the hydraulic cylinder. Hydraulic circuit for a construction machine, characterized in that it comprises a pressure sensor for detecting the pressure generated in the first and second chambers.