Flow rate control apparatus of construction equipment and control method therefor

Patent metadata

Field	Value
Publication number	US-10428491-B2
Application number	US-201515565701-A
Country	US
Kind code	B2
Filing date	Apr 29, 2015
Priority date	Apr 29, 2015
Publication date	Oct 1, 2019
Grant date	Oct 1, 2019

Abstract

A flow rate control apparatus for construction equipment includes: a boom cylinder driven by hydraulic fluid; a first control valve for controlling a hydraulic fluid flow supplied to the boom cylinder; an option actuator driven by hydraulic fluid; a second control valve for controlling a hydraulic fluid flow supplied to the option actuator; a boom cylinder manipulation lever and an option actuator manipulation lever; a confluence line selectively confluence the hydraulic fluid supplied to the boom cylinder with the hydraulic fluid of the option actuator; a center bypass switching valve provided at the furthest downstream side of a fluid supply path of the first hydraulic pump; a confluence switching valve selectively opening and closing the confluence line; a confluence selection valve applying a pilot pressure to the confluence switching valve; and a controller for controlling the confluence selection valve.

First claim

The invention claimed is:

1. A flow rate control apparatus for construction equipment, the apparatus comprising:
first and, second variable displacement hydraulic pumps and a pilot pump;
a boom cylinder driven by a hydraulic fluid of the first hydraulic pump;
a first control valve controlling a flow of the hydraulic fluid supplied from the first hydraulic pump to the boom cylinder;
an option actuator driven by a hydraulic fluid of the second hydraulic pump;
a second control valve controlling a flow of the hydraulic fluid supplied from the second hydraulic pump to the option actuator;
a boom cylinder manipulation lever for inputting a manipulation signal to control the first control valve, and an option actuator manipulation lever for inputting a manipulation signal to control the second control valve;
a confluence line connected at an inlet port thereof to a downstream side of a supply path of the first hydraulic pump, and connected at an outlet port thereof to a meter-in port of the second control valve;
a center bypass switching valve provided in the furthest downstream side of the supply path of the first hydraulic pump, and operated to close an opening port thereof by a pilot pressure applied thereto;
a confluence switching valve provided in the confluence line, and joining a part of the hydraulic fluid supplied from the first hydraulic pump to the boom cylinder with the hydraulic fluid of the option actuator when the confluence switching valve is operated to open an opening port thereof;
a confluence selection valve provided in a fluid path between the pilot pump and the confluence switching valve, and applying the pilot pressure to the confluence switching valve when the confluence switching valve is operated; and
a controller controlling the confluence selection valve to block the pilot pressure supplied from the pilot pump to the confluence switching valve so that the confluence line becomes closed when combined work of the boom cylinder and the option actuator is performed.

2. The apparatus of claim 1 , wherein when the boom cylinder or the option actuator is independently driven, the controller applies an electric signal to the confluence selection valve so that the confluence switching valve is operated by the pilot pressure supplied from the pilot pump to open the confluence line.

3. The apparatus of claim 1 , further comprising: a first shuttle valve connected at inlet ports thereof to the boom cylinder manipulation lever and the confluence selection valve and connected at an outlet port thereof to the center bypass switching valve, and operating the center bypass switching valve by applying thereto a selected pilot pressure among the pilot pressure from the boom cylinder manipulation lever and the pilot pressure from the confluence selection'valve so that a part of the hydraulic fluid supplied to the boom cylinder is joined to the hydraulic fluid of the option actuator.

4. The apparatus of claim 1 , wherein the confluence switching valve includes:
a logic valve provided in the confluence line; and
a switching valve provided in a fluid path between a back pressure chamber of the logic valve and the confluence selection valve, and operating the logic valve to open the logic valve by draining a hydraulic fluid of the back pressure chamber so that the confluence line becomes open when the switching valve is operated by the pilot pressure of the confluence selection valve.

5. The apparatus of claim 1 , further comprising, as a means for supplying the pilot pressure to the confluence selection valve to operate the confluence switching valve,
a proportional control valve provided in a fluid path between the pilot pump and the second control valve, and converting a manipulation pressure supplied from the pilot pump into a second, pressure corresponding to an electric signal output from the controller, and applying the converted second pressure to the second control valve; and
a second shuttle valve connected to at an inlet port thereof to a fluid path between the proportional control valve and the second control valve, and connected at an outlet port thereof to the confluence selection valve so that a selected pilot pressure among pilot pressures applied to left and right pressure ports of the second control valve is applied to the confluence switching valve via operation of the confluence selection valve.

6. The apparatus of claim 1 , further comprising: a check valve provided in the confluence line and preventing a reverse flow of the hydraulic fluid when a load pressure generated in the option actuator is higher than a load pressure generated in the boom cylinder.

7. The apparatus of claim 1 , further comprising:
a first pressure sensor detecting the pilot pressure applied to the first control valve by a manipulation of the boom cylinder manipulation lever, and outputting a signal indicative of the detected pilot pressure to the controller; and
a second pressure sensor detecting the pilot pressure applied to the second control valve by a manipulation of the option actuator manipulation lever, and outputting a signal indicative of the detected pilot pressure to the controller.

8. A flow rate control method of construction equipment, wherein the construction equipment comprising:
first and second variable displacement hydraulic pumps and a pilot pump;
a boom cylinder and an option actuator respectively connected to the first and second hydraulic pumps;
first and second control valves respectively controlling flows of a hydraulic fluid supplied to the boom cylinder and the option actuator;
a boom cylinder manipulation lever and an option actuator manipulation lever;
a confluence line selectively supplying the hydraulic fluid of the first hydraulic pump to the hydraulic fluid of the second hydraulic pump;
a confluence switching valve opening and closing the confluence line;
a confluence selection valve provided in a fluid path between the pilot pump and the confluence switching valve;
first and second pressure sensors respectively detecting pilot pressures applied to the first and second control valves by manipulations of the boom cylinder manipulation lever and the option actuator manipulation lever; and
a controller connected to the first and second pressure sensors and the confluence selection valve, the method comprising:
receiving manipulation signals from the boom cylinder manipulation lever and the option actuator manipulation lever for driving the boom cylinder and the option actuator;
determining whether or not combined work of the boom cylinder and the option actuator is performed by using signals indicative of detection results of the first and second pressure sensors; and
blocking a pilot pressure applied to the confluence switching valve so that the confluence line becomes closed when the combined work of the boom cylinder and the option actuator is performed.

9. The method of claim 8 , further comprising: when the boom cylinder or the option actuator is independently driven, in order to open the confluence line, operating the confluence switching valve by applying the pilot pressure thereto.

Assignees

• Volvo Constr Equip Ab
• Joung Hea Gyoon

Inventors

• Joung Hea-Gyoon
• Tak Jin-Young

Classifications

• E02F9/22

  Hydraulic or pneumatic drives {(for dipper or bucket arm position control E02F3/43, for blade position control for graders E02F3/844; for turntables E02F9/121; for fork-lift trucks B66F9/22)} · CPC title

• E02F9/20

  Drives; Control devices (gearings in general F16H; controlling in general G05; electric multi-motor drives H02K, H02P) · CPC title

• F15B2211/6316

  the pressure being a pilot pressure · CPC title

• E02F9/2292

  Systems with two or more pumps · CPC title

• E02F9/2282 Primary

  Systems using center bypass type changeover valves · CPC title