# US 9,518,371 B2 · Method for improving excavating operation characteristic and grading operation characteristic of excavator > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,518,371 B2 - Document ID: US9518371B2 - Status: Granted - Kind: B2 - Application number: 13/933,395 - Filed: 2013-07-02 - Published: 2014-01-09 - Granted: 2016-12-13 - Earliest claimed: 2011-01-11 - Assignees: Xcmg Excavator Machinery Co., Ltd - Applicants: Xcmg Excavator Machinery Co., Ltd - Inventors: Yong Wang; Hong Zhang; Shengxia Zhang; Kai Liu; Zong Li; Jian Zhang; Mingjun Liao; Jiasheng Qin; Yufeng Yang - Web page: https://patentgrep.com/patent/US9518371B2 ## CPC - E02F 3/844: {for positioning the blade, e.g. hydraulically} - E02F 3/435: {for dipper-arms, backhoes or the like} - E02F 9/2242: {including an electronic controller} - E02F 9/2282: {Systems using center bypass type changeover valves} - E02F 9/2285: {Pilot-operated systems} - E02F 9/2292: {Systems with two or more pumps} - E02F 9/2296: {Systems with a variable displacement pump} - F15B 11/17: using two or more pumps - F15B 2211/20546: variable capacity - F15B 2211/20576: with multiple pumps - F15B 2211/3116: the pump port being open in the centre position, e.g. so-called open centre - F15B 2211/329: actuated by fluid pressure - Y10T 137/0318: Processes - E02F: DREDGING; SOIL-SHIFTING (winning peat E21C49/00) - F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A method for improving excavating operation characteristic and grading operation characteristic of an excavator is disclosed. A hydraulically controlled selector valve is added in a boom confluence control circuit of a hydraulic excavator, and a solenoid valve group is added in the boom confluence control circuit and the bucket/stick confluence control circuit. A controller sends a control signal to switch the solenoid valve group between a disconnected mode and a connected mode. The controller may send out a signal to disconnect the solenoid valve group, to restore a valve spool to a middle position, to restore a boom lifting confluence circuit, and to disconnect a bucket/stick swinging confluence circuit to perform a standard excavation mode. The controller may send out a signal to connect the solenoid valve group to disconnect a boom lifting confluence circuit and to increase a bucket/stick swinging confluence circuit to achieve a grading operation mode. ## Claims ### Claim 1 A method for improving excavating operation characteristic and grading operation characteristic of an excavator including a boom, a stick and a bucket, the method comprising: adding a hydraulically controlled selector valve (7) to a boom confluence control circuit for controlling the boom in a hydraulic excavator; adding a solenoid valve group (4) to control both the boom confluence control circuit and a stick confluence control circuit; and when the solenoid valve group (4) receives a control signal, performing a switching between a disconnected mode and a connected mode of the solenoid valve group (4) such that the excavator switches between an excavation operation and a grading operation; wherein, based on the control signal, the solenoid valve group (4) is in the disconnected mode to restore a boom lifting confluence circuit, and to disconnect a stick swinging confluence circuit to perform the excavation operation; or wherein, based on the control signal, the solenoid valve group (4) is in the connected mode to disconnect the boom lifting confluence circuit and to restore the stick swinging confluence circuit to perform the grading operation. ### Claim 2 (depends on 1) The method of claim 1, wherein: in the excavation operation, a pressure sensing end of the hydraulically controlled selector valve (7) detects a control pressure signal of a stick excavation; and when a control pressure value of the stick excavation is smaller than a change-direction pressure of the hydraulically controlled selector valve (7), the hydraulically controlled selector valve (7) does not change direction such that: a pilot control oil passage controls a boom cylinder (10) and a stick cylinder (9), and hydraulic oil is entirely supplied by a double pump confluence corresponding to a double pump confluence circuit. ### Claim 3 (depends on 2) The method of claim 2, wherein, when the control pressure value of the stick excavation reaches the change-direction pressure of the hydraulically controlled selector valve (7), the hydraulically controlled selector valve (7) changes direction to disconnect the boom confluence control circuit and to independently supply oil to the boom by a single pump, while the double pump confluence circuit is used for stick excavation. ### Claim 4 (depends on 1) The method of claim 1, wherein, in the grading operation, an electrical signal controlling end of the solenoid valve group (4) receives a change-direction command. ### Claim 5 (depends on 1) The method of claim 1, wherein, after receiving the change-direction command, the solenoid valve group (4) changes direction, a pilot control oil passage changes allocation of a double pump confluence, the boom confluence control circuit of boom lifting hydraulic oil is disconnected and is replaced by using a single pump to supply oil to the boom, the stick excavation uses the double pump confluence, and a hydraulic oil passage of stick swinging is connected to be the double pump confluence. ### Claim 6 (depends on 1) The method of claim 1, wherein the change-direction pressure of the hydraulically controlled selector valve (7) is adjusted by a pressure adjustment spring inside the hydraulically controlled selector valve (7). ### Claim 7 A method for improving excavating operation characteristic and grading operation characteristic of an excavator including a boom, a stick and a bucket, the method comprising: receiving a control signal by a solenoid valve group (4) that controls both a boom confluence control circuit and a stick confluence control circuit for controlling a confluence for the stick, such that: the solenoid valve group (4) switches between a disconnected mode and a connected mode, and the excavator switches between an excavation operation and a grading operation; performing the excavation operation, when the solenoid valve group (4) is in the disconnected mode to restore a boom lifting confluence circuit, and to disconnect a stick swinging confluence circuit; detecting a control pressure value of a stick excavation by a hydraulically controlled selector valve (7) configured in the boom confluence control circuit for controlling the boom of the excavator; and when the control pressure value of the stick excavation reaches a change-direction pressure of the hydraulically controlled selector valve (7) to change a direction, disconnecting the boom confluence control circuit but independently supplying oil to the boom by an additional single pump, while the double pump confluence circuit is only used for the stick excavation. ### Claim 8 (depends on 7) The method of claim 7, wherein: when a control pressure value of the stick excavation is smaller than the change-direction pressure of the hydraulically controlled selector valve (7), the hydraulically controlled selector valve (7) does not change direction such that: a pilot control oil passage controls a boom cylinder (10) and a stick cylinder (9), and hydraulic oil is entirely supplied by a double pump confluence corresponding to the double pump confluence circuit. ### Claim 9 (depends on 7) The method of claim 7, further including: performing the grading operation, when the solenoid valve group (4) is in the connected mode to disconnect the boom lifting confluence circuit and to restore the stick swinging confluence circuit. ### Claim 10 (depends on 9) The method of claim 9, wherein, when performing the grading operation, an electrical signal controlling end of the solenoid valve group (4) receives a change-direction command. ### Claim 11 (depends on 10) The method of claim 10, wherein, after receiving the change-direction command, the solenoid valve group (4) changes a direction such that: a pilot control oil passage changes allocation of a double pump confluence, the boom confluence control circuit of boom lifting hydraulic oil is disconnected and is replaced by using an additional single pump to supply oil to the boom, the stick excavation uses the double pump confluence, and a hydraulic oil passage of swinging the stick is connected to be the double pump confluence. ### Claim 12 (depends on 7) The method of claim 7, wherein the change-direction pressure of the hydraulically controlled selector valve (7) is adjusted by a pressure adjustment spring inside the hydraulically controlled selector valve (7).