Hydraulic system of a working machine vehicle and working machine vehicle

Abstract

The application discloses a hydraulic system of an engineering mechanical vehicle and the engineering mechanical vehicle, and relates to the technical field of hydraulic control of engineering mechanical vehicles. The hydraulic system of the engineering mechanical vehicle comprises a main pump, a main valve group, a differential valve group and a hydraulic cylinder. The differential valve group comprises a valve body and a logic valve. The valve body is provided with a first inlet and outlet oil port, a second inlet and outlet oil port, a third inlet and outlet oil port and a fourth inlet and outlet oil port. The first inlet and outlet oil port is in communication with a first working oil port of the main valve group, the second inlet and outlet oil port is in communication with a rodless chamber of the hydraulic cylinder, and the first inlet and outlet oil port and the second inlet and outlet oil port are in communication. The third inlet and outlet oil port is in communication with a second working oil port of the main valve group, the fourth inlet and outlet oil port is in communication with a rod chamber of the hydraulic cylinder, and the third inlet and outlet oil port can be in communication with the fourth inlet and outlet oil port. The logic valve is arranged in the valve body. When the first working oil port of the main valve group discharges oil, the rod chamber of the hydraulic cylinder drives the logic valve to open through oil return, so that the oil return oil enters the rodless chamber of the hydraulic cylinder through the logic valve.

Description

Technical Field

[0001] This invention relates to the field of hydraulic control technology for engineering machinery vehicles, and more particularly to a hydraulic system for engineering machinery vehicles and an engineering machinery vehicle. Background Technology

[0002] With the needs of market development and construction, there is an increasing number of differentiated engineering machinery vehicles, such as excavators, adapted to special working conditions. For example, excavators used in low-ceilinged spaces such as tunnels and basements often employ... Figure 1 The boom cylinder shown is positioned at the bottom, thus saving operating space.

[0003] In existing 300mm under-mounted boom cylinder excavators, after modifying the working device structure, the hydraulic system has not undergone any special optimization, such as... Figure 2 As shown, the boom cylinder 300 is directly connected to the main valve assembly 2, and the control method is the same as that of the boom 100 of the excavator before the modification. The only difference is that the oil inlet direction of the large and small chambers has been changed. When the boom cylinder 300 extends, the boom 100 swings outward; when the boom cylinder 300 retracts, the boom 100 retracts. As a result, when the boom 100 is digging, the effective working area of ​​the hydraulic oil is the rod chamber, which greatly reduces the digging force. If the diameter of the boom cylinder 300 is increased in order to meet the digging force of the boom 100, the boom swing will then be oiled through the rodless chamber, and the swing speed will be slower. Compared with excavators of the same tonnage, the speed may even be reduced to 1 / 2. Summary of the Invention

[0004] The purpose of this invention is to provide a hydraulic system for engineering machinery vehicles and an engineering machinery vehicle, so as to improve the extension speed of the cylinder rod of the hydraulic cylinder and thus improve the work efficiency.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] The hydraulic system of an engineering machinery vehicle includes a main pump, a main valve assembly, and a hydraulic cylinder. The main pump supplies oil to the hydraulic cylinder through the main valve assembly to drive the extension and retraction of the cylinder rod. The hydraulic system also includes a differential valve assembly located between the main valve assembly and the hydraulic cylinder. The differential valve assembly includes a valve body and a logic valve. The valve body has a first inlet / outlet, a second inlet / outlet, a third inlet / outlet, and a fourth inlet / outlet. The first inlet / outlet is connected to the first working port of the main valve assembly. The second inlet / outlet is connected to the rodless chamber of the hydraulic cylinder, and the first and second inlet / outlet are connected. The third inlet / outlet is connected to the second working port of the main valve assembly, and the fourth inlet / outlet is connected to the rod chamber of the hydraulic cylinder, and the third inlet / outlet can communicate with the fourth inlet / outlet.

[0007] The logic valve is arranged in the valve body, when the first working oil port of the main valve group discharges oil and the second working oil port returns oil, the return oil of the rod cavity of the hydraulic cylinder enters the logic valve through the fourth inlet and outlet port, and the logic valve can be driven to open, so that the return oil enters the rodless cavity of the hydraulic cylinder through the logic valve and the second inlet and outlet port.

[0008] As an optional solution of the hydraulic system of the engineering mechanical vehicle, the logic valve comprises a spring cavity and a conical cavity, the spring cavity is provided with a control oil port, the conical cavity is provided with a first oil port and a second oil port, the first oil port can communicate with the first inlet and outlet port and the second inlet and outlet port, the second oil port communicates with the fourth inlet and outlet port, and the control oil port communicates with the third inlet and outlet port; when the first working oil port of the main valve group discharges oil and the second working oil port returns oil, the return oil of the rod cavity of the hydraulic cylinder can enter the conical cavity through the fourth inlet and outlet port and the second oil port, and the return oil of the spring cavity enters the second working oil port of the main valve group through the control oil port and the third inlet and outlet port to open the logic valve.

[0009] As an optional solution of the hydraulic system of the engineering mechanical vehicle, the differential valve group further comprises a first one-way valve and a second one-way valve, the first one-way valve is used for one-way conduction of the first oil port to the first inlet and outlet port and the second inlet and outlet port; and the second one-way valve is used for one-way conduction of the third inlet and outlet port to the fourth inlet and outlet port and the second oil port.

[0010] As an optional solution of the hydraulic system of the engineering mechanical vehicle, a first control oil path is arranged in the valve body, the first control oil path is used for communicating the control oil port and the third inlet and outlet port; a first throttling member is arranged on the first control oil path, when the logic valve is opened, the return oil of the spring cavity enters the second working oil port of the main valve group through the first throttling member and the third inlet and outlet port.

[0011] As an optional solution of the hydraulic system of the engineering mechanical vehicle, a third one-way valve is further arranged on the first control oil path, the third one-way valve is used for one-way conduction of the third inlet and outlet port to the control oil port, when the second working oil port of the main valve group discharges oil and the first working oil port returns oil, the oil entering the valve body through the third inlet and outlet port enters the spring cavity through the third one-way valve and the control oil port, and the oil of the conical cavity enters the first working oil port of the main valve group through the first oil port and the first inlet and outlet port to return oil, so as to drive the logic valve to close.

[0012] As an optional solution of the hydraulic system of the engineering mechanical vehicle, the first throttling member is a first throttling valve, and the first throttling valve and the third one-way valve are arranged in parallel.

[0013] As an alternative of the hydraulic system of the engineering mechanical vehicle, the differential valve group further comprises a second throttling member, the spring cavity and the conical cavity are communicated through the second throttling member; the flow area of the first throttling member is larger than that of the second throttling member.

[0014] As an alternative of the hydraulic system of the engineering mechanical vehicle, the second throttling member is a second throttling valve, a second control oil path is further arranged in the valve body, the second control oil path is used for communicating the control oil port and the second oil port, and the second throttling valve is arranged on the second control oil path.

[0015] As an alternative of the hydraulic system of the engineering mechanical vehicle, the main valve group comprises a reversing valve and a holding valve, the first working oil port and the second working oil port are arranged in the reversing valve, the oil outlet of the main pump is communicated with the oil inlet of the reversing valve, the oil return port of the reversing valve is communicated with the oil tank, the first working oil port is communicated with the oil inlet of the holding valve, and the oil outlet of the holding valve is communicated with the first inlet and outlet oil port.

[0016] The engineering mechanical vehicle comprises an execution element, and the execution element is driven by the hydraulic system of the engineering mechanical vehicle according to any one of the above schemes.

[0017] As an alternative of the engineering mechanical vehicle, the engineering mechanical vehicle comprises an excavator, the execution element of the excavator comprises a swing arm and a bucket rod, the bucket rod is driven by the hydraulic system, the hydraulic cylinder is a bucket rod cylinder, the bucket rod cylinder is arranged below the swing arm and the bucket rod, the cylinder body of the bucket rod cylinder is fixed to the swing arm, and the cylinder rod of the bucket rod cylinder is connected with the bucket rod.

[0018] The present application has the following beneficial effects:

[0019] The hydraulic system of the engineering machinery vehicle provided by the application, the main pump supplies oil to the hydraulic cylinder through the main valve group to drive the cylinder rod of the hydraulic cylinder to extend or retract, and the differential valve group is arranged between the main valve group and the hydraulic cylinder to realize that when the cylinder rod of the hydraulic cylinder extends, the return oil of the rod cavity of the hydraulic cylinder enters the rodless cavity of the hydraulic cylinder through the differential valve group, and the extension speed of the cylinder rod of the hydraulic cylinder is improved. The differential valve group comprises a valve body and a logic valve, the valve body is provided with a first inlet and outlet port in communication with the first working oil port of the main valve group, a second inlet and outlet port in communication with the rodless cavity of the hydraulic cylinder, a third inlet and outlet port in communication with the second working oil port of the main valve group, and a fourth inlet and outlet port in communication with the rod cavity of the hydraulic cylinder, and the logic valve is arranged in the valve body; when the first working oil port of the main valve group discharges oil and the second working oil port returns oil, the oil enters the rodless cavity of the hydraulic cylinder through the first inlet and outlet port and the second inlet and outlet port, and the return oil of the rod cavity of the hydraulic cylinder enters the logic valve through the fourth inlet and outlet port, so that the logic valve can be driven to be opened to enable the return oil to enter the rodless cavity of the hydraulic cylinder through the logic valve and the second inlet and outlet port, the extension speed of the cylinder rod of the hydraulic cylinder is improved, and the working efficiency is improved.

[0020] The engineering machinery vehicle provided by the application comprises an execution element, the execution element is driven by the hydraulic system of the engineering machinery vehicle, the differential of the return oil of the rod cavity of the hydraulic cylinder to the rodless cavity of the hydraulic cylinder is realized through the differential valve group, the extension speed of the cylinder rod of the hydraulic cylinder is improved, and the working efficiency of the execution element is improved. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a structure schematic view of the execution element and the arm cylinder of the excavator provided by the prior art;

[0022] Figure 2 It is a principle view of the hydraulic system of the arm of the excavator provided by the prior art;

[0023] Figure 3 It is a principle view of the hydraulic system of the engineering machinery vehicle provided by the embodiment of the application;

[0024] Figure 4 It is a principle view of the differential valve group provided by the embodiment of the application.

[0025] In the drawings:

[0026] 100, arm; 200, boom; 300, arm cylinder;

[0027] 1, main pump; 2, main valve group; 3, hydraulic cylinder; 4, differential valve group; 5, oil tank;

[0028] 11, first main pump; 12, second main pump; 21, first directional valve; 22, second directional valve; 23, main relief valve; 24, overload protection valve; 25, holding valve; 41, valve body; 42, logic valve; 43, first check valve; 44, second check valve; 45, third check valve; 46, first restrictor; 47, second restrictor;

[0029] 411, first inlet and outlet port; 412, second inlet and outlet port; 413, third inlet and outlet port; 414, fourth inlet and outlet port; 415, first communication oil passage; 416, second communication oil passage; 417, third communication oil passage; 418, fourth communication oil passage; 421, first oil port; 422, second oil port; 423, control oil port;

[0030] 4191, first control oil passage; 4192, second control oil passage. DETAILED DESCRIPTION

[0031] Embodiments of the present application are described in detail below with reference to the attached drawing figures, wherein like reference numerals identify identical or like elements throughout the views. The embodiments described below are exemplary in nature, and are intended to illustrate the present application, but are not intended to limit the present application.

[0032] The technical solutions of the present application are further illustrated below in conjunction with the drawings and through specific embodiments.

[0033] The present embodiment provides an engineering machinery vehicle, comprising an execution element, the execution element is driven by a hydraulic system of the engineering machinery vehicle.

[0034] Exemplarily, as shown in Figure 1 and Figure 2 The engineering machinery vehicle comprises an excavator, the execution element of the excavator comprises a boom 200 and a stick 100, the stick 100 is driven by a hydraulic system, the hydraulic system comprises a main pump 1, a main valve group 2 and a stick cylinder 300, the main pump 1 supplies oil for the stick cylinder 300 through the main valve group 2 to drive the rod of the stick cylinder 300 to extend and retract.

[0035] Specifically, the main pump 1 comprises a first main pump 11 and a second main pump 12, the main valve group 2 comprises a reversing valve and a holding valve 25, the first working oil port and the second working oil port are arranged on the reversing valve, the oil outlet of the main pump 1 is communicated with the oil inlet of the reversing valve, the oil return port of the reversing valve is communicated with the oil tank 5, the first working oil port is communicated with the oil inlet of the holding valve 25, and the oil outlet of the holding valve 25 is communicated with the rodless cavity of the arm cylinder 300, so as to prevent the rod of the arm cylinder 300 from retracting and play a holding role. The reversing valve comprises a first reversing valve 21 and a second reversing valve 22, the first main pump 11 supplies oil to the first reversing valve 21, the second main pump 12 supplies oil to the second reversing valve 22, the oil in the first working oil ports of the first reversing valve 21 and the second reversing valve 22 is combined to supply oil to the rodless cavity of the arm cylinder 300, and the oil in the second working oil ports of the first reversing valve 21 and the second reversing valve 22 is combined to supply oil to the rod cavity of the arm cylinder 300, so as to meet the requirement that the hydraulic system can provide more oil flow and increase the digging force.

[0036] The main valve group 2 further comprises a main overflow valve 23 and an overload protection valve 24, the oil outlets of the first main pump 11 and the second main pump 12 are both communicated with the oil inlet of the main overflow valve 23, and the oil outlet of the main overflow valve 23 is communicated with the oil tank 5, so as to realize pressure relief through the main overflow valve 23 when the pressure of the first main pump 11 and / or the second main pump 12 is too large. The rod cavity of the arm cylinder 300 is communicated with the oil tank 5 through the overload protection valve 24, so as to realize overload protection of the arm cylinder 300.

[0037] In the embodiment, the arm cylinder 300 is arranged below the boom 200 and the arm 100, the cylinder body of the arm cylinder 300 is fixed to the boom 200, and the rod of the arm cylinder 300 is connected with the arm 100. Arranging the arm cylinder 300 below the boom 200 and the arm 100 can save operation space, but the rodless cavity of the arm cylinder 300 is communicated with the first working oil port of the main valve group 2, the rod cavity of the arm cylinder 300 is communicated with the second working oil port of the main valve group 2, the rod of the arm cylinder 300 extends out and the arm 100 swings out when the first working oil port discharges oil and the second working oil port returns oil, and the rod of the arm cylinder 300 retracts and the arm 100 is retracted when the second working oil port discharges oil and the first working oil port returns oil, which results in that the effective operation area of hydraulic oil is the rod cavity when the arm 100 digs, and the digging force is greatly reduced. If the rodless cavity is supplied with oil when the arm 100 swings out in order to meet the requirement of the digging force of the arm 100, the swinging speed of the arm 100 will be slow, and compared with excavators of the same tonnage, the swinging speed of the arm 100 will be reduced to one half.

[0038] To solve the above technical problems, as shown in the drawings, Figure 3 and Figure 4The hydraulic system of the engineering machinery vehicle provided by the embodiment comprises a main pump 1, a main valve group 2, a hydraulic cylinder 3, and a differential valve group 4 arranged between the main valve group 2 and the hydraulic cylinder 3. The differential valve group 4 comprises a valve body 41 and a logic valve 42. The valve body 41 is provided with a first inlet and outlet port 411, a second inlet and outlet port 412, a third inlet and outlet port 413, and a fourth inlet and outlet port 414. The first inlet and outlet port 411 is in communication with a first working oil port of the main valve group 2. The second inlet and outlet port 412 is in communication with a rodless chamber of the hydraulic cylinder 3. The first inlet and outlet port 411 and the second inlet and outlet port 412 are in communication. The third inlet and outlet port 413 is in communication with a second working oil port of the main valve group 2. The fourth inlet and outlet port 414 is in communication with a rod chamber of the hydraulic cylinder 3. The third inlet and outlet port 413 can be in communication with the fourth inlet and outlet port 414. The logic valve 42 is arranged in the valve body 41. When the first working oil port of the main valve group 2 discharges oil and the second working oil port returns oil, the oil enters the rodless chamber of the hydraulic cylinder 3 through the first inlet and outlet port 411 and the second inlet and outlet port 412. The return oil of the rod chamber of the hydraulic cylinder 3 enters the logic valve 42 through the fourth inlet and outlet port 414, which can drive the logic valve 42 to open, so that the return oil enters the rodless chamber of the hydraulic cylinder 3 through the logic valve 42 and the second inlet and outlet port 412, thereby improving the extension speed of the rod of the hydraulic cylinder 3 and improving the work efficiency.

[0039] Specifically, the logic valve 42 comprises a spring cavity and a tapered cavity. The spring cavity is provided with a control oil port 423. The tapered cavity is provided with a first oil port 421 and a second oil port 422. The first oil port 421 can be in communication with the first inlet and outlet port 411 and the second inlet and outlet port 412. The second oil port 422 is in communication with the fourth inlet and outlet port 414. The control oil port 423 is in communication with the third inlet and outlet port 413. When the first working oil port of the main valve group 2 discharges oil and the second working oil port returns oil, the return oil of the rod chamber of the hydraulic cylinder 3 can enter the tapered cavity through the fourth inlet and outlet port 414 and the second oil port 422. The return oil of the spring cavity enters the second working oil port of the main valve group 2 through the control oil port 423 and the third inlet and outlet port 413, which opens the logic valve 42, so that the return oil of the rod chamber of the hydraulic cylinder 3 can be differentially returned to the rodless chamber, without interfering with the oil inlet of the rod chamber of the hydraulic cylinder 3, thereby improving the extension speed of the rod of the hydraulic cylinder 3. When the second working oil port of the main valve group 2 discharges oil and the first working oil port returns oil, the oil enters the spring cavity through the third inlet and outlet port 413 and the control oil port 423. The oil in the tapered cavity enters the first working oil port of the main valve group 2 through the first oil port 421 and the first inlet and outlet port 411, which drives the logic valve 42 to close, so that the oil enters the rod chamber of the hydraulic cylinder 3 through the fourth inlet and outlet port 414. The return oil of the rodless chamber of the hydraulic cylinder 3 enters the first working oil port of the main valve group 2 through the second inlet and outlet port 412 and the first inlet and outlet port 411.

[0040] The valve body 41 is provided with a first communication oil passage 415, a second communication oil passage 416, a third communication oil passage 417, a fourth communication oil passage 418 and a control oil passage. The first inlet and outlet oil port 411 and the second inlet and outlet oil port 412 are communicated through the first communication oil passage 415. The first oil port 421 can be communicated with the first inlet and outlet oil port 411 through the second communication oil passage 416. The second oil port 422 is communicated with the fourth inlet and outlet oil port 414 through the third communication oil passage 417. The fourth communication oil passage 418 is used to communicate the third inlet and outlet oil port 413 and the third communication oil passage 417. The control oil port 423 is communicated with the third inlet and outlet oil port 413 through the control oil passage.

[0041] The valve body 41 is further provided with a first mounting cavity. The logic valve 42 is detachably arranged in the first mounting cavity. According to the flow range applied, the logic valve 42 with a flow area matched with the flow range applied is selected, so that the application flow range of the differential valve group 4 is greatly expanded, the versatility is better, and the cost is low.

[0042] Further, the logic valve 42 comprises a logic valve seat, a logic valve core and a second spring. The logic valve seat is arranged in the first mounting cavity. One end of the second spring is fixed to the valve body 41, and the other end is connected with the logic valve core. The logic valve seat is provided with a limiting step. The outer periphery of the logic valve core is provided with a limiting surface. The logic valve core is slidably arranged in the logic valve seat. The limiting surface is a tapered surface, which divides the logic valve seat into a spring cavity and a tapered cavity. The oil entering the spring cavity drives the logic valve core to move towards the tapered cavity. The limiting surface abuts against the limiting step, and the logic valve 42 is closed. The oil entering the tapered cavity drives the logic valve core to move towards the spring cavity. The limiting surface is separated from the limiting step, and the logic valve 42 is opened.

[0043] Further, the opening pressure of the logic valve 42 is m, and 1 bar < m < 10 bar. For example, the opening pressure of the logic valve 42 can be 6 bar, 7 bar or 8 bar, etc. Those skilled in the art can debug according to the application scene of different flow range. The elastic coefficient of the second spring determines the opening pressure of the logic valve 42. The second spring is selected according to the opening pressure of the logic valve 42. The greater the elastic coefficient of the second spring, the greater the hardness. The greater the hardness of the second spring, the better the closing characteristics of the logic valve 42. However, if the second spring is too hard, it will affect the micro-control of the hydraulic oil cylinder 3.

[0044] Further, the area ratio of the spring cavity and the tapered cavity is n, and 1.5 < n < 2. If the area ratio of the spring cavity and the tapered cavity is too large, it will affect the opening pressure of the logic valve 42, and further affect the opening time of the logic valve 42.

[0045] In order to limit the flow direction of the hydraulic oil, the differential valve group 4 further comprises a first one-way valve 43 and a second one-way valve 44, the first one-way valve 43 being used for one-way conduction of the first oil port 421 to the first inlet and outlet oil port 411 and the second inlet and outlet oil port 412, and the second one-way valve 44 being used for one-way conduction of the third inlet and outlet oil port 413 to the fourth inlet and outlet oil port 414 and the second oil port 422.

[0046] The first one-way valve 43 is arranged in the second communication oil passage 416 and is used for one-way conduction of the first oil port 421 to the second inlet and outlet oil port 412, and the second one-way valve 44 is arranged in the fourth communication oil passage 418 and is used for one-way conduction of the third inlet and outlet oil port 413 to the fourth inlet and outlet oil port 414 and the second oil port 422. When the first working oil port of the main valve group 2 discharges and the second working oil port returns oil, the first one-way valve 43 is used to limit the flow direction of the oil, so that the oil entering from the first inlet and outlet oil port 411 enters the rodless cavity of the hydraulic cylinder 3 through the second inlet and outlet oil port 412. The second one-way valve 44 limits the flow direction of the oil, so that the return oil of the rod cavity of the hydraulic cylinder 3 enters the rodless cavity of the hydraulic cylinder 3, forming a differential circuit. When the third inlet and outlet oil port 413 admits oil, the oil enters the rod cavity of the hydraulic cylinder 3 through the second one-way valve 44 and the fourth inlet and outlet oil port 414, and the first one-way valve 43 limits the flow direction of the return oil of the rodless cavity of the hydraulic cylinder 3, so that the return oil of the second inlet and outlet oil port 412 flows to the first inlet and outlet oil port 411. The holding valve 25 is arranged between the reversing valve and the differential valve group 4, the first working oil port is communicated with the oil inlet of the holding valve 25, and the oil outlet of the holding valve 25 is communicated with the first inlet and outlet oil port 411. The first one-way valve 43 and the holding valve 25 jointly act to ensure that the rodless cavity of the hydraulic cylinder 3 does not leak when the rodless cavity of the hydraulic cylinder 3 is subjected to gravity, thereby playing a holding role.

[0047] Specifically, the first one-way valve 43 and the second one-way valve 44 are each provided with a reset spring, and the reset spring is as small as possible in opening pressure under the premise of meeting the reset of the one-way valve, and in some cases the reset spring in the one-way valve can be removed.

[0048] The valve body 41 is further provided with a third mounting cavity and a fourth mounting cavity, the third mounting cavity is arranged on the second communication oil passage 416, and the first one-way valve 43 is mounted in the third mounting cavity. The fourth mounting cavity is arranged on the fourth communication oil passage 418, and the second one-way valve 44 is mounted in the fourth mounting cavity.

[0049] When the first working oil port discharges oil and the second working oil port returns oil, the oil enters the first inlet and outlet port 411, enters the rodless cavity of the hydraulic cylinder 3 through the first communication oil path 415 and the second inlet and outlet port 412, the return oil of the rod cavity of the hydraulic cylinder 3 enters the conical cavity through the fourth inlet and outlet port 414, the third communication oil path 417 and the second oil port 422, the return oil of the spring cavity communicates with the third inlet and outlet port 413 through the control oil path and the control oil port, and the logic valve 42 is opened. The return oil of the rod cavity of the hydraulic cylinder 3 enters the rodless cavity of the hydraulic cylinder 3 through the logic valve 42 and the first one-way valve 43; the differential of the rodless cavity of the hydraulic cylinder 3 is realized, so that the cylinder rod of the hydraulic cylinder 3 is quickly extended, and the working efficiency is improved. When the second working oil port discharges oil and the first working oil port returns oil, the oil enters the spring cavity through the third inlet and outlet port 413, the control oil path and the control oil port 423, the logic valve 42 is closed, so that the oil enters the rod cavity of the hydraulic cylinder 3 through the second one-way valve 44, and the return oil of the rodless cavity of the hydraulic cylinder 3 enters the first inlet and outlet port 411 through the second inlet and outlet port 412 and the first communication oil path 415.

[0050] Specifically, the first control oil path 4191 is arranged in the valve body 41, and the first control oil path 4191 is used for communicating the control oil port 423 and the third inlet and outlet port 413; the first control oil path 4191 is provided with the first throttling part 46, when the logic valve 42 is opened, the return oil of the spring cavity enters the second working oil port of the main valve group 2 through the first throttling part 46 and the third inlet and outlet port 413. When the first inlet and outlet port 411 enters oil, the return oil of the rod cavity of the hydraulic cylinder 3 enters the third communication oil path 417 through the fourth inlet and outlet port 414, and then enters the conical cavity through the second oil port 422, drives the logic valve core to move to the direction close to the spring cavity until the limiting surface and the limiting step are separated from each other, the return oil of the spring cavity can only return to the third inlet and outlet port 413 through the first throttling part 46, and the logic valve 42 is slowly opened, so that the impact brought by the differential flow is reduced.

[0051] Further, the first control oil path 4191 is further provided with the third one-way valve 45, the third one-way valve 45 is used for one-way conduction of the third inlet and outlet port 413 to the control oil port 423, the second working oil port of the main valve group 2 discharges oil, and the first working oil port returns oil, the oil entering the valve body 41 through the third inlet and outlet port 413 enters the spring cavity through the third one-way valve 45 and the control oil port 423, the oil of the conical cavity enters the first working oil port of the main valve group 2 through the first oil port 421 and the first inlet and outlet port 411, and drives the logic valve 42 to be closed.

[0052] In an alternative embodiment of the present application, the first throttling member 46 is a first throttling hole. Specifically, the third check valve 45 comprises a check valve seat, a check valve core and a first spring, a second mounting cavity is arranged in the first control oil passage 4191 and is arranged in the valve body 41. The check valve seat is fixed to one end of the second mounting cavity, the first spring is fixed to the other end of the second mounting cavity, the check valve core is arranged between the check valve seat and the first spring, the end of the second mounting cavity close to the check valve seat is in communication with the third inlet and outlet oil port 413, and the end of the second mounting cavity close to the first spring is in communication with the control oil port 423; the oil flowing from the third inlet and outlet oil port 413 to the control oil port 423 drives the check valve core to move relative to the check valve seat to communicate the third inlet and outlet oil port 413 and the control oil port 423. The first throttling hole is arranged in the check valve core, and the first throttling hole and the check valve core are coaxially arranged, so that the oil in the spring cavity can flow to the third inlet and outlet oil port 413 through the first throttling hole. By arranging the first throttling hole in the center of the check valve core of the third check valve 45, when the third check valve 45 is closed, the return oil of the spring cavity can also flow to the third inlet and outlet oil port 413 through the first throttling hole in the center of the check valve core. When the third inlet and outlet oil port 413 is filled with oil, the oil entering the third inlet and outlet oil port 413 flows into the spring cavity through the third check valve 45 and the control oil port 423, drives the logic valve core to move towards the tapered cavity until the limiting surface abuts against the limiting step, thereby closing the logic valve 42, so that the oil enters the rod cavity of the hydraulic cylinder 3 through the fourth inlet and outlet oil port 414.

[0053] In an alternative embodiment of the present application, the first throttling member 46 is a first throttling hole. Specifically, the third check valve 45 comprises a check valve seat, a check valve core and a first spring, a second mounting cavity is arranged in the first control oil passage 4191 and is arranged in the valve body 41. The check valve seat is fixed to one end of the second mounting cavity, the first spring is fixed to the other end of the second mounting cavity, the check valve core is arranged between the check valve seat and the first spring, the end of the second mounting cavity close to the check valve seat is in communication with the third inlet and outlet oil port 413, and the end of the second mounting cavity close to the first spring is in communication with the control oil port 423; the oil flowing from the third inlet and outlet oil port 413 to the control oil port 423 drives the check valve core to move relative to the check valve seat to communicate the third inlet and outlet oil port 413 and the control oil port 423. The first throttling hole is arranged in the check valve core, and the first throttling hole and the check valve core are coaxially arranged, so that the oil in the spring cavity can flow to the third inlet and outlet oil port 413 through the first throttling hole. By arranging the first throttling hole in the center of the check valve core of the third check valve 45, when the third check valve 45 is closed, the return oil of the spring cavity can also flow to the third inlet and outlet oil port 413 through the first throttling hole in the center of the check valve core. When the third inlet and outlet oil port 413 is filled with oil, the oil entering the third inlet and outlet oil port 413 flows into the spring cavity through the third check valve 45 and the control oil port 423, drives the logic valve core to move towards the tapered cavity until the limiting surface abuts against the limiting step, thereby closing the logic valve 42, so that the oil enters the rod cavity of the hydraulic cylinder 3 through the fourth inlet and outlet oil port 414.

[0054] The opening pressure of the first spring is preferably as small as possible to reset the check valve core.

[0055] In order to reduce the leakage of the differential valve group 4, the differential valve group 4 further comprises a second throttling member 47, the spring cavity and the tapered cavity are communicated through the second throttling member 47, so that when the third inlet and outlet oil port 413 is filled with oil, the oil enters the spring cavity through the first control oil passage 4191, the oil in the tapered cavity enters the spring cavity through the second throttling member 47, and under the action of the second spring, the limiting surface of the logic valve core abuts against the limiting step of the logic valve seat. In addition, when the rod cavity of the hydraulic cylinder 3 is affected by gravity, the spring cavity and the tapered cavity are communicated, and under the action of the second spring, the logic valve core is tightly pressed against the logic valve seat, so that the pressure oil in the tapered cavity is not leaked, thereby playing a retaining role.

[0056] Further, the flow area of the first throttling member 46 is greater than the flow area of the second throttling member 47. The flow area of the second throttling member 47 is set to be less than the flow area of the first throttling member 46, so that the oil return of the spring cavity is greater than the oil intake of the conical cavity, to ensure that when the oil is taken in through the first intake and discharge port 411, the oil return of the rod cavity of the hydraulic cylinder 3 can smoothly push open the logic valve 42 into the rodless cavity of the hydraulic cylinder 3, to realize the differential of the rodless cavity of the hydraulic cylinder 3.

[0057] In an optional embodiment of the present application, the second throttling member 47 is a second throttling valve, and the valve body 41 further has a second control oil passage 4192 for connecting the control oil port 423 and the second oil port 422, and the second throttling valve is arranged on the second control oil passage 4192. The second throttling member 47 is set as the second throttling valve, so that when the oil is taken in through the third intake and discharge port 413, the oil return of the conical cavity enters the spring cavity through the second control oil passage 4192, so that the logic valve core is pressed against the logic valve seat to prevent leakage.

[0058] In another optional embodiment of the present application, the second throttling member 47 is a second throttling hole arranged in the logic valve core, and the second throttling hole and the logic valve core are coaxially arranged to connect the control oil port 423 and the second oil port 422. By arranging the second throttling hole in the center of the logic valve core, the communication between the spring cavity and the conical cavity is realized, and the effect of preventing leakage is also achieved.

[0059] The hydraulic system of the engineering mechanical vehicle provided in the embodiment is applied to an excavator, and is used to drive the dipper arm 100. The hydraulic cylinder 3 is a dipper arm cylinder 300. When the dipper arm cylinder 300 is arranged below the boom 200 and the dipper arm 100, the differential valve group 4 is arranged to realize the differential circuit when the dipper arm 100 is swung out, so that the oil return of the rod cavity of the dipper arm cylinder 300 enters the rodless cavity of the dipper arm cylinder 300 through the logic valve 42. At this time, the flow of the oil of the main pump 1 only needs to supplement the volume of the cylinder rod, and the swing-out speed of the dipper arm 100 is greatly increased. Through the comparison test of a 15-ton excavator, the swing-out speed of the dipper arm 100 of the hydraulic system without the differential valve group 4 is 4 seconds, and the swing-out speed of the dipper arm 100 of the hydraulic system with the differential valve group 4 is 2.2 seconds, which greatly improves the operation efficiency of the dipper arm 100.

[0060] Of course, the application of the hydraulic system of the engineering mechanical vehicle provided in the embodiment is not limited to the driving of the dipper arm 100 of the excavator, but can also be applied to the driving of the execution element whose hydraulic cylinder 3 is arranged below the execution element, such as a pile driver, to improve the operation efficiency of the execution element.

[0061] The above merely preferred embodiments of the present application, for those skilled in the art, according to the idea of the present application, in the specific implementation and application range will have changes, the content of the description should not be understood as limiting the present application.

Claims

1. Hydraulic system of a construction machine vehicle, comprising a main pump (1), a main valve group (2) and a hydraulic cylinder (3), the main pump (1) supplying the hydraulic cylinder (3) with oil through the main valve group (2) to drive the cylinder rod of the hydraulic cylinder (3) to extend and retract, characterized in that, The hydraulic system further comprises a differential valve group (4) arranged between the main valve group (2) and the hydraulic cylinder (3), the differential valve group (4) comprising a valve body (41) and a logic valve (42), the valve body (41) being provided with a first inlet and outlet oil port (411), a second inlet and outlet oil port (412), a third inlet and outlet oil port (413) and a fourth inlet and outlet oil port (414), the first inlet and outlet oil port (411) being communicated with the first working oil port of the main valve group (2), the second inlet and outlet oil port (412) being communicated with the rodless cavity of the hydraulic cylinder (3), the first inlet and outlet oil port (411) and the second inlet and outlet oil port (412) being communicated, the third inlet and outlet oil port (413) being communicated with the second working oil port of the main valve group (2), the fourth inlet and outlet oil port (414) being communicated with the rod cavity of the hydraulic cylinder (3), the third inlet and outlet oil port (413) being capable of being communicated with the fourth inlet and outlet oil port (414); The logic valve (42) is arranged in the valve body (41), when the first working oil port of the main valve group (2) discharges oil and the second working oil port returns oil, the return oil of the rod cavity of the hydraulic cylinder (3) enters the logic valve (42) through the fourth inlet and outlet oil port (414), which can drive the logic valve (42) to open, so that the return oil enters the rodless cavity of the hydraulic cylinder (3) through the logic valve (42) and the second inlet and outlet oil port (412). The logic valve (42) comprises a conical cavity, the conical cavity is provided with a first oil port (421) and a second oil port (422), the first oil port (421) is capable of being communicated with the first inlet and outlet oil port (411) and the second inlet and outlet oil port (412), the second oil port (422) is communicated with the fourth inlet and outlet oil port (414); The differential valve group (4) further comprises a first one-way valve (43) and a second one-way valve (44), the first one-way valve (43) is used for one-way conduction of the first oil port (421) to the first inlet and outlet oil port (411) and the second inlet and outlet oil port (412); the second one-way valve (44) is used for one-way conduction of the third inlet and outlet oil port (413) to the fourth inlet and outlet oil port (414) and the second oil port (422).

2. Hydraulic system of a working machine vehicle according to claim 1, characterized in that, The logic valve (42) further comprises a spring cavity, the spring cavity is provided with a control oil port (423), the control oil port (423) is communicated with the third inlet and outlet oil port (413); when the first working oil port of the main valve group (2) discharges oil and the second working oil port returns oil, the return oil of the rod cavity of the hydraulic cylinder (3) can enter the conical cavity through the fourth inlet and outlet oil port (414) and the second oil port (422), the return oil of the spring cavity enters the second working oil port of the main valve group (2) through the control oil port (423) and the third inlet and outlet oil port (413) to return oil, which opens the logic valve (42).

3. Hydraulic system of a working machine vehicle according to claim 2, characterized in that, The valve body (41) is further provided with a first control oil passage (4191) for connecting the control oil port (423) and the third inlet and outlet oil port (413); the first control oil passage (4191) is provided with a first throttling element (46), when the logic valve (42) is opened, the oil return of the spring cavity enters the second working oil port of the main valve group (2) through the first throttling element (46) and the third inlet and outlet oil port (413).

4. Hydraulic system of a working machine vehicle according to claim 3, characterized in that, The first control oil passage (4191) is further provided with a third one-way valve (45) for one-way conduction from the third inlet and outlet oil port (413) to the control oil port (423), when the second working oil port of the main valve group (2) is oil outlet and the first working oil port is oil return, the oil entering the valve body (41) through the third inlet and outlet oil port (413) enters the spring cavity through the third one-way valve (45) and the control oil port (423), and the oil in the conical cavity enters the first working oil port of the main valve group (2) through the first oil port (421) and the first inlet and outlet oil port (411), which drives the logic valve (42) to close.

5. Hydraulic system of a working machine vehicle according to claim 4, characterized in that, The first throttling element (46) is a first throttling valve, and the first throttling valve and the third one-way valve (45) are arranged in parallel.

6. The hydraulic system of the construction machine vehicle according to claim 3, characterized by, The differential valve group (4) further comprises a second throttling element (47), and the spring cavity and the conical cavity are connected through the second throttling element (47); the flow area of the first throttling element (46) is greater than that of the second throttling element (47).

7. Hydraulic system of a working machine vehicle according to claim 6, characterized in that, The second throttling element (47) is a second throttling valve, and the valve body (41) is further provided with a second control oil passage (4192) for connecting the control oil port (423) and the second oil port (422), and the second throttling valve is arranged on the second control oil passage (4192).

8. The hydraulic system of the construction machine vehicle according to Claim 1, characterized by, The main valve group (2) comprises a reversing valve and a holding valve (25), the first working oil port and the second working oil port are arranged on the reversing valve, the oil outlet of the main pump (1) is connected with the oil inlet of the reversing valve, the oil return port of the reversing valve is connected with the oil tank (5), the first working oil port is connected with the oil inlet of the holding valve (25), and the oil outlet of the holding valve (25) is connected with the first inlet and outlet oil port (411).

9. A working machine vehicle characterised in that The hydraulic system of the engineering machinery vehicle comprises an execution element, and the execution element is driven by the hydraulic system.

10. The working machine vehicle of claim 9, wherein, The engineering machinery vehicle comprises an excavator, the execution element of the excavator comprises a boom (200) and a stick (100), the stick (100) is driven by the hydraulic system, the hydraulic cylinder (3) is a stick cylinder (300), the stick cylinder (300) is arranged below the boom (200) and the stick (100), the cylinder body of the stick cylinder (300) is fixed to the boom (200), and the cylinder rod of the stick cylinder (300) is connected with the stick (100).

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