Hydraulic control system and loader

Abstract

The present invention discloses a hydraulic control system and a loader, which relate to the field of hydraulic control technology. The hydraulic control system includes a working pump, a steering pump, a pilot valve, a multi-way valve and an execution module, the multi-way valve includes a conversion valve and a working valve group, the steering pump is connected to the working valve group, a first oil circuit is formed between the steering pump and the working valve group, the working pump is connected to the working valve group, a second oil circuit is formed between the working pump and the working valve group, the conversion valve is arranged on the second oil circuit, the working valve group is connected to the execution module; the pilot valve is connected to the working valve group; the pilot valve is used to control the working valve group to switch to a working state, the conversion valve is used to cut off or conduct according to the working state of the working valve group, the conversion valve is used to cut off the second oil circuit to achieve pressure relief, and the conversion valve is used to conduct the second oil circuit to merge the first oil circuit and the second oil circuit, so as to achieve optimal distribution of flow and achieve energy saving.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic control, and in particular to a hydraulic control system and a loader. Background Art

[0002] The operating conditions of the loader are mainly excavation and loading operations. In order to operate efficiently, the whole machine needs to turn left and right frequently, and the execution module needs to frequently perform bucket collection, lifting, unloading, lowering, etc. The above actions are all controlled and realized by the loader hydraulic system.

[0003] The loader hydraulic system generally includes an execution module hydraulic system and a steering hydraulic system. In the prior art, if two pumps (such as a working pump and a steering pump) are used to control the execution module and the steering device separately, the hydraulic system efficiency is low and the optimal flow matching cannot be achieved when performing compound actions. If the execution module hydraulic system and the steering hydraulic system adopt a mixed system, that is, when the steering hydraulic system is not working, the steering hydraulic system is diverted through the diverter valve device and merged with the working pump to supply oil to the loader multi-way valve; the confluence can be achieved, which can optimize the flow distribution to a certain extent, but the structure is complex, the hydraulic system is complex, and the cost is high. Summary of the invention

[0004] The objects of the present invention include, for example, providing a hydraulic control system and a loader, which can realize the merging and unloading of a steering pump and a working pump, and the hydraulic system has high energy-saving efficiency.

[0005] The embodiments of the present invention can be implemented as follows:

[0006] In a first aspect, the present invention provides a hydraulic control system, comprising a working pump, a steering pump, a pilot valve, a multi-way valve and an execution module, wherein the multi-way valve comprises a conversion valve and a working valve group, the steering pump is connected to the working valve group, a first oil circuit is formed between the steering pump and the working valve group, the working pump is connected to the working valve group, a second oil circuit is formed between the working pump and the working valve group, the conversion valve is arranged on the second oil circuit, and the working valve group is connected to the execution module;

[0007] The pilot valve is connected to the working valve group; the pilot valve is used to control the working valve group to switch to a working state, the conversion valve is used to cut off or connect according to the working state of the working valve group, the conversion valve is used to cut off the second oil circuit to achieve pressure relief, and the conversion valve is used to connect the second oil circuit to allow the first oil circuit and the second oil circuit to merge.

[0008] In an optional embodiment, the load sensing oil port of the working valve group is connected to the compensator of the steering pump to adjust the displacement of the steering pump.

[0009] In an optional embodiment, the execution module includes an execution cylinder, and the working valve group includes a first control end, a second control end, a first working position, a second working position and a third working position, the first control end and the second control end are respectively connected to the pilot valve, the pilot valve is connected to the first control end, the working valve group is in the first working position, the working valve group is connected to the large chamber of the execution cylinder, and the large chamber of the execution cylinder is filled with oil; the pilot valve is connected to the second control end, the working valve group is in the second working position, the working valve group is connected to the small chamber of the execution cylinder, and the small chamber of the execution cylinder is filled with oil; there is no communication between the pilot valve and the working valve group, the working valve group is in the third working position, and the oil circuit between the working valve group and the execution cylinder is cut off.

[0010] In an optional embodiment, the working valve group is in the first working position or the second working position, and the working valve group is connected to the first chamber of the conversion valve. If the oil pressure difference between the hydraulic oil entering the first chamber and the oil pressure of the load is less than or equal to a preset pressure, the conversion valve is in a conducting state, and the working pump is connected to the working valve group via the conversion valve; if the oil pressure difference between the hydraulic oil entering the first chamber and the oil pressure of the load is greater than the preset pressure, the conversion valve is in a cut-off state, and the oil at the outlet of the working pump enters the oil return channel of the multi-way valve through the conversion valve and then returns to the oil tank.

[0011] In an optional embodiment, a relief valve is further included, wherein the high-pressure end of the relief valve is connected to the working valve group, and the other end is connected to the oil tank; the second chamber of the conversion valve is connected to the high-pressure end of the relief valve. If the oil pressure of the working valve group is higher than the pressure set by the relief valve, the hydraulic oil of the working valve group is depressurized through the relief valve, and the oil pressure of the second chamber is depressurized to put the conversion valve in a cut-off state, and the oil at the outlet of the working pump enters the oil return channel of the multi-way valve through the conversion valve and then returns to the oil tank.

[0012] In an optional embodiment, it also includes an oil replenishing valve and a back pressure valve. The working valve group is in the second working position. The return oil of the working valve group enters the first return oil channel. The first return oil channel is connected to the oil tank through the back pressure valve; the oil inlet of the oil replenishing valve is connected to the first return oil channel, and the oil outlet is connected to the small chamber of the actuator cylinder.

[0013] In an optional embodiment, it also includes a floating oil make-up valve, the working valve group is in the second working position, the pilot valve is connected to the control port of the floating oil make-up valve, the oil outlet of the floating oil make-up valve is connected to the first oil return oil channel, the floating oil make-up valve is connected to the small chamber of the actuator cylinder, and the first oil return oil channel is connected to the small chamber of the actuator cylinder via the floating oil make-up valve.

[0014] In an optional embodiment, a rapid descending valve is further included, the working valve group is in the second working position, and the control port of the rapid descending valve is connected to the pilot valve;

[0015] The oil entering the control port of the rapid descent valve from the pilot valve drives the rapid descent valve to communicate with the first oil return passage, so that the large chamber of the actuator cylinder is communicated with the oil tank.

[0016] In an optional embodiment, a shuttle valve is further included, the working valve group is connected to the shuttle valve, the shuttle valve is connected to the conversion valve, and the shuttle valve is connected to the steering pump via the load sensing oil port.

[0017] In an optional embodiment, a pressure reducing valve is further included, and the pressure reducing valve is arranged on the control oil circuit between the pilot valve and the large chamber of the actuator cylinder.

[0018] In a second aspect, the present invention provides a loader, comprising the hydraulic control system described in any one of the aforementioned embodiments.

[0019] The beneficial effects of the embodiments of the present invention include, for example:

[0020] In the hydraulic control system provided by the embodiment of the present invention, the pilot valve controls the working state of the working valve group, and the conversion valve is used to open according to the working state of the working valve group, conduct the second oil circuit, control the confluence of the working pump, and increase the flow entering the working valve group to meet the working requirements. Alternatively, the conversion valve is used to close according to the working state of the working valve group, cut off the second oil circuit, control the unloading of the working pump, and reduce the flow entering the working valve group to meet the working requirements. The optimal matching of the flow can be automatically achieved, and the energy saving efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 A schematic diagram of the hydraulic system principle provided by an embodiment of the present invention;

[0023] Figure 2 for Figure 1 An enlarged schematic diagram of the hydraulic control system of the multi-way valve;

[0024] Figure 3 for Figure 1 An enlarged schematic diagram of the hydraulic control system of the steering pump.

[0025] Icons: 100-multi-way valve; 101-working pump; 103-steering pump; 104-compensator; 105-pilot valve; 106-priority valve; 107-oil tank; 109-system shuttle valve; 120-shuttle valve; 130-floating control valve; 131-bucket oil supply valve; 140-floating oil supply valve; 150-fast descending valve; 160-overflow valve; 170-main safety valve; 200-conversion valve; 301-boom cylinder; 303-bucket cylinder; 310-boom control valve; 350-turn Bucket control valve; 401-steering gear; 410-back pressure valve; 420-third one-way valve; 430-first one-way valve; 440-second one-way valve; 460-pressure reducing valve; EF-second oil inlet; LS-load sensing oil port; ls-load sensing oil channel; P-first oil inlet; T1-first return oil channel; xA1-third pilot oil inlet; xA2-first pilot oil inlet; xB1-fourth pilot oil inlet; xB2-second pilot oil inlet; csl-first chamber; cls-second chamber. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0029] In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. appear to indicate an orientation or position relationship, they are based on the orientation or position relationship shown in the accompanying drawings, or are the orientation or position relationship in which the product of the invention is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0030] In addition, the terms “first”, “second”, etc., if used, are merely used to distinguish between the descriptions and should not be understood as indicating or implying relative importance.

[0031] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention may be combined with each other.

[0032] Please refer to Figures 1 to 3 The present embodiment provides a hydraulic control system, including a working pump 101, a steering pump 103, a pilot valve 105, a multi-way valve 100 and an execution module, the multi-way valve 100 includes a conversion valve 200 and a working valve group, the steering pump 103 is connected to the working valve group, a first oil circuit is formed between the steering pump 103 and the working valve group, the working pump 101 is connected to the working valve group, a second oil circuit is formed between the working pump 101 and the working valve group, the conversion valve 200 is arranged on the second oil circuit, and the working valve group is connected to the execution module; the pilot valve 105 is connected to the working valve group; the pilot valve 105 is used to control the working valve group to switch to a working state, the conversion valve 200 is used to cut off or conduct according to the working state of the working valve group, the conversion valve 200 is used to cut off the second oil circuit to achieve pressure relief, and the conversion valve 200 is used to conduct the second oil circuit to merge the first oil circuit and the second oil circuit. The pilot valve 105 controls the working state of the working valve group, and the conversion valve 200 is used to open according to the working state of the working valve group, conduct the second oil circuit, control the confluence of the working pump 101, and increase the flow entering the working valve group to meet the working requirements. Or the conversion valve 200 is used to close according to the working state of the working valve group, cut off the second oil circuit, control the unloading of the working pump 101, and reduce the flow entering the working valve group to meet the working requirements. The best matching of the flow can be automatically achieved, and the energy saving efficiency is high.

[0033] The execution module includes an execution cylinder, and the working valve group includes a first control end, a second control end, a first working position, a second working position and a third working position. The first control end and the second control end are respectively connected to the pilot valve 105, the pilot valve 105 is connected to the first control end, the working valve group is in the first working position, the working valve group is connected to the large chamber of the execution cylinder, and oil enters the large chamber of the execution cylinder; the pilot valve 105 is connected to the second control end, the working valve group is in the second working position, the working valve group is connected to the small chamber of the execution cylinder, and oil enters the small chamber of the execution cylinder; there is no communication between the pilot valve 105 and the working valve group, the working valve group is in the third working position, and the oil circuit between the working valve group and the execution cylinder is cut off.

[0034] The working valve group is in the first working position or the second working position, and the working valve group is connected to the first chamber csl of the conversion valve 200. If the difference between the oil pressure of the hydraulic oil entering the first chamber csl and the oil pressure of the load is less than or equal to the preset pressure, the conversion valve 200 is in the on state, and the working pump 101 is connected to the working valve group through the conversion valve 200; if the difference between the oil pressure of the hydraulic oil entering the first chamber csl and the oil pressure of the load is greater than the preset pressure, the conversion valve 200 is in the cut-off state, and the oil at the outlet of the working pump 101 enters the oil return channel of the multi-way valve 100 through the conversion valve 200 and then returns to the oil tank 107. It should be noted that the conversion valve 200 is provided with a first chamber csl and a second chamber cls, the second chamber cls is connected to the load sensing oil channel ls, and the first chamber csl is connected to the first oil circuit, that is, Figure 2 In the P2 oil passage shown, the oil in the first chamber csl is connected to the load oil. It can be understood that if the oil pressure difference between the hydraulic oil entering the first chamber csl and the oil pressure of the second chamber cls is less than or equal to the preset pressure, the conversion valve 200 is in the conducting state, and if the oil pressure difference between the hydraulic oil entering the first chamber csl and the oil pressure of the second chamber cls is greater than the preset pressure, the conversion valve 200 is in the cut-off state.

[0035] It should be noted that if the engine is started, the pilot valve 105 is not operated, and the working valve group is in the cut-off state, at this time, the oil of the steering pump 103 reaches the working valve group through the first oil path, and the other path returns to the oil tank 107 through the priority valve 106 and the steering gear 401. At this time, the LS oil port is connected to the oil tank 107 through the boom control valve 310 and the bucket control valve 350. Under the control of the built-in regulator, the steering pump 103 enters the full hydraulic steering gear 401 through the priority valve 106 at the minimum pressure and minimum flow rate of 0.5-2L / min set by the regulator, and returns oil through the return pipe of the steering gear 401, thereby achieving energy saving. Optionally, the set pressure of the regulator is generally 16-24 bar, and the pressure acts on the conversion valve 200 at the same time, so that the conversion valve 200 is in the closed state, and the oil from the working pump 101 enters the oil tank 107 through the conversion valve 200 and unloads at low pressure, thereby achieving the purpose of energy saving.

[0036] Optionally, the hydraulic control system includes a relief valve 160, the high-pressure end of the relief valve 160 is connected to the working valve group, and the other end is connected to the oil tank 107; the second chamber cls of the conversion valve 200 is connected to the high-pressure end of the relief valve 160. If the oil pressure of the working valve group is higher than the pressure set by the relief valve 160, the hydraulic oil of the working valve group is depressurized through the relief valve 160, and the oil pressure of the second chamber cls is depressurized, so that the conversion valve 200 is in a cut-off state, and the oil at the outlet of the working pump 101 enters the oil return passage of the multi-way valve 100 through the conversion valve 200 and then returns to the oil tank 107, so as to realize the unloading of the working pump 101 under high-pressure state. It should be noted that the oil return passage of the multi-way valve 100 is connected to the oil tank 107, and a back pressure valve 410 is provided between the oil return passage of the multi-way valve 100 and the first oil return passage T1.

[0037] Optionally, the hydraulic control system includes a main safety valve 170, the high-pressure end of the main safety valve 170 is connected to the first oil inlet P and the second oil inlet EF respectively, and the low-pressure end is connected to the oil tank 107, so as to prevent the working pressure of the system from being too high and improve the safety of operation. In this embodiment, the high-pressure end of the main safety valve 170 is connected to the confluent oil circuit after the first oil circuit and the second oil circuit are confluent.

[0038] The multi-way valve 100 also includes an oil replenishing valve and a back pressure valve 410. When the working valve group is in the second working position, the return oil of the working valve group enters the first oil return oil passage T1, and the first oil return oil passage T1 is connected to the oil tank 107 through the back pressure valve 410; the oil inlet of the oil replenishing valve is connected to the first oil return oil passage T1, and the oil outlet is connected to the small chamber of the actuator cylinder to replenish oil for the small chamber of the actuator cylinder. When the working valve group is in the second working position, the oil outlet of the working valve group is connected to the small chamber of the actuator cylinder, and a vacuum occurs in the small chamber of the actuator cylinder, which is lower than the atmospheric pressure; the first oil return oil passage T1 is connected to the oil tank 107 through the back pressure valve 410. Due to the back pressure PT1 generated by the back pressure valve 410, the return oil of the first oil return oil passage T1 pushes open the oil replenishing valve to replenish oil for the small chamber of the actuator cylinder, thereby avoiding a vacuum in the small chamber of the boom cylinder 301 and burning the seal.

[0039] The multi-way valve 100 further includes a fast descending valve 150. The working valve group is in the second working position. The fast descending valve 150 is respectively connected with the pilot valve 105, the large chamber of the actuator oil cylinder and the first oil return oil passage T1; the oil entering the control port of the fast descending valve 150 from the pilot valve 105 drives the fast descending valve 150 to communicate with the oil tank 107, and the return oil of the large chamber of the actuator oil cylinder is directly connected with the oil tank 107 through the fast descending valve 150. Optionally, the pilot oil acts on the fast descending valve 150, so that the fast descending valve 150 is connected with the oil tank 107 and the pressure is relieved, so that the return oil of the large chamber of the actuator oil cylinder is directly connected with the oil tank 107 through the fast descending valve 150, so as to achieve the purpose of fast oil return and fast descending of the actuator module, so as to improve the working efficiency.

[0040] Optionally, the multi-way valve 100 further includes a shuttle valve 120, the working valve group is connected to the shuttle valve 120, the shuttle valve 120 is connected to the conversion valve 200, and the shuttle valve 120 is connected to the steering pump 103 through the load sensing oil port LS. When the working valve group is in the first working position or the second working position, a part of the oil at the oil inlet of the working valve group enters the execution oil cylinder, and the other part enters the load sensing oil passage ls through the shuttle valve 120; a part of the hydraulic oil entering the load sensing oil passage ls acts on the conversion valve 200, and the conversion valve 200 is controlled to be turned on or off according to the working pressure of the working valve group. If the pressure at the oil inlet of the working valve group is small, the conversion valve 200 is in the on state, and the oil of the working pump 101 merges with the oil of the steering pump 103 through the conversion valve 200, increasing the flow entering the execution oil cylinder to meet the working needs of the execution module. If the pressure at the oil inlet of the working valve group is relatively high, the conversion valve 200 is in the cut-off state, and the oil of the working pump 101 flows back to the oil tank 107 through the conversion valve 200. The working pump 101 is unloaded, reducing the flow entering the execution cylinder to meet the working needs of the execution module.

[0041] Another part of the hydraulic oil entering the load sensing oil channel 1s acts on the compensator 104 of the steering pump 103 through the system shuttle valve 109 to adjust the displacement of the steering pump 103, automatically increasing or decreasing the displacement of the steering pump 103 to meet the working needs of the execution module.

[0042] In this embodiment, the working valve group includes a boom control valve 310 and a bucket control valve 350. The first oil circuit output by the steering pump 103 is connected to the boom control valve 310 through the first check valve 430, and is connected to the bucket control valve 350 through the second check valve 440. The oil output by the working pump 101 merges with the first oil circuit through the conversion valve 200 and the third check valve 420. After merging, they are respectively connected to the boom control valve 310 through the first check valve 430 and are connected to the bucket control valve 350 through the second check valve 440. The execution cylinder includes a boom cylinder 301 and a bucket cylinder 303. The boom control valve 310 is connected to the boom cylinder 301 to realize the lifting and lowering of the boom. The bucket cylinder 303 is connected to the bucket control valve 350 to realize the retracting and unloading of the bucket.

[0043] The multi-way valve 100 is provided with pilot oil inlets, including a first pilot oil inlet xA2, a second pilot oil inlet xB2, a third pilot oil inlet xA1 and a fourth pilot oil inlet xB1, which are respectively connected to the pilot valve 105. The first pilot oil inlet xA2 and the second pilot oil inlet xB2 are respectively connected to the boom control valve 310, and the third pilot oil inlet xA1 and the fourth pilot oil inlet xB1 are respectively connected to the bucket control valve 350. Optionally, the pilot valve 105 controls the oil supply to the first pilot oil inlet xA2, the boom control valve 310 is in the first working position, the oil inlet of the boom control valve 310 is connected to the large cavity of the boom cylinder 301, and the boom is lifted; the pilot valve 105 controls the oil supply to the second pilot oil inlet xB2, the boom control valve 310 is in the second working position, the oil inlet of the boom control valve 310 is connected to the small cavity of the boom cylinder 301, and the boom is lowered; the pilot valve 105 controls the oil supply to the third pilot oil inlet xA1, the bucket control valve 350 is in the first working position, the oil inlet of the bucket control valve 350 is connected to the large cavity of the bucket cylinder 303, and the bucket is retracted; the pilot valve 105 controls the oil supply to the fourth pilot oil inlet xB1, the bucket control valve 350 is in the second working position, the oil inlet of the bucket control valve 350 is connected to the small cavity of the bucket cylinder 303, and the bucket is unloaded.

[0044] Optionally, the oil replenishing valve includes a floating oil replenishing valve 140 and a bucket oil replenishing valve 131, the floating oil replenishing valve 140 is connected to the boom cylinder 301 to replenish oil for the small chamber of the boom cylinder 301, and the bucket oil replenishing valve 131 is connected to the bucket cylinder 303 to replenish oil for the small chamber of the bucket cylinder 303. In this embodiment, the working valve group is in the second working position, the pilot valve 105 is connected to the control port of the floating oil replenishing valve 140, the oil outlet of the floating oil replenishing valve 140 is connected to the oil return channel, the floating oil replenishing valve 140 is connected to the large chamber of the actuator cylinder, and the first oil return channel T1 is connected to the small chamber of the actuator cylinder through the floating oil replenishing valve 140. It can be understood that during the boom lowering process, that is, the boom control valve 310 is in the second working position, oil enters the small chamber of the boom cylinder 301, and the oil in the large chamber of the boom cylinder 301 returns through the boom control valve 310 and enters the first return oil channel T1. Due to the back pressure generated by the back pressure valve 410, the oil in the first return oil channel T1 enters the floating oil replenishing valve 140. The floating oil replenishing valve 140 is turned on, so that the oil in the first return oil channel T1 passes through the floating oil replenishing valve 140 and merges with the oil entering the small chamber of the boom cylinder 301 from the working chamber of the boom control valve 310, so that the execution module is in a floating state, which facilitates the movement of the execution module during the lowering process.

[0045] Optionally, the floating oil replenishing valve 140 is connected to the floating control valve 130, the outlet of the floating control valve 130 is connected to the inlet of the floating oil replenishing valve 140, and the hydraulic oil in the first oil return passage T1 is connected to the small chamber of the boom cylinder 301 after passing through the floating control valve 130 and the floating oil replenishing valve 140, so that the oil circuit layout is more concise and the control efficiency of the hydraulic system is high. It can be understood that when the floating control valve 130 is working, the floating oil replenishing valve 140 plays a floating role, and when the floating control valve 130 is not working, the floating oil replenishing valve 140 plays an oil replenishing role.

[0046] Optionally, it further includes a priority valve 106 and a steering gear 401, wherein the oil inlet of the priority valve 106 is connected to the steering pump 103, and the oil outlet is connected to the working valve group, that is, the oil output by the steering pump 103 enters the second oil inlet EF of the multi-way valve 100 through the priority valve 106. The steering gear 401 is connected to the priority valve 106, and is used for a part of the oil of the priority valve 106 to enter the second chamber cls of the conversion valve 200 when the working valve group is in the third working position, and control the conversion valve 200 to be in the cut-off unloading state, and the other part of the oil is returned through the steering gear 401, so as to achieve system energy saving.

[0047] According to a hydraulic control system provided in this embodiment, its working principle is as follows:

[0048] The first working condition: the engine is not started, the working pump 101 and the steering pump 103 are not working. The boom control valve 310 and the bucket control valve 350 are respectively in the third working position, that is, the middle closed state. The conversion valve 200 is in the open state. The load sensing oil port LS is connected to the oil tank 107.

[0049] The second working condition: after the engine is started, the steering gear 401 is not turned; the pilot valve 105 is not operated, and the boom control valve 310 and the bucket control valve 350 are respectively in the third working position; the hydraulic oil output by the steering pump 103 enters the second oil inlet EF of the multi-way valve 100 through the priority valve 106, enters the boom control valve 310 through the first check valve 430 and then returns to the oil tank 107, and enters the bucket control valve 350 through the second check valve 440 and then returns to the oil tank 107. It can be understood that part of the oil enters the load sensing oil passage ls and is connected to the load sensing oil port LS. At this time, the load sensing oil passage ls is connected to the oil tank 107, and the steering pump 103, under the control of the built-in regulator, enters the full hydraulic steering gear 401 through the priority valve 106 at the minimum pressure and minimum flow rate of 0.5-2L / min set by the regulator, and returns oil through the return oil pipe of the steering gear 401, thereby achieving energy saving. Optionally, the set pressure of the regulator is generally 16 to 24 bar, and the pressure acts on the conversion valve 200 at the same time, so that the conversion valve 200 is in a closed state, and the oil from the working pump 101 returns to the oil tank 107 after passing through the conversion valve 200 and unloads at low pressure.

[0050] The third working condition: after the engine is started, the steering system is not turned; the pilot valve 105 is operated, such as operating the boom lever to lift, the first pilot oil inlet xA2 enters the pilot oil, and the boom control valve 310 is controlled to be in the first working position, that is, Figure 2 In the left position, the oil of the steering pump 103 enters the large chamber of the boom cylinder 301 through the boom control valve 310; the hydraulic oil in the small chamber of the boom cylinder 301 enters the boom control valve 310 and flows back to the oil tank 107. At the same time, part of the oil at the oil inlet of the boom control valve 310 enters the load sensing oil passage ls through the shuttle valve 120 and communicates with the load sensing oil port LS.

[0051] A part of the pressure oil entering the load sensing oil passage ls is connected to the system shuttle valve 109 through the load sensing oil port LS, and acts on the spring chamber of the compensator 104 of the steering pump 103 through the x oil passage. The displacement of the steering pump 103 is increased to meet the flow demand of the hydraulic system of the actuator module. The steering pump 103 can use a variable piston pump with higher pressure.

[0052] The pressure oil that enters the load sensing oil passage 1s, and the other part enters the conversion valve 200 to control the conduction or closing of the conversion valve 200. If the oil pressure is less than or equal to the preset pressure set by the conversion valve 200, the conversion valve 200 remains open, and the oil of the working pump 101 merges with the oil of the steering pump 103 through the conversion valve 200 to increase the flow rate to meet the working needs of the execution module, so as to speed up the lifting of the boom of the execution module. If the oil pressure is greater than the preset pressure set by the conversion valve 200, the conversion valve 200 is closed, the working pump 101 is unloaded, the flow output is reduced, and energy saving is achieved.

[0053] It can be understood that when the operator controls the boom lifting state in a micro-motion manner, that is, the hydraulic oil pressure entering the load sensing oil channel ls from the oil inlet of the boom control valve 310 is relatively large, greater than the preset pressure set by the conversion valve 200, the conversion valve 200 switches to a closed state, and the incoming oil of the working pump 101 returns after passing through the conversion valve 200, thereby controlling the working pump 101 to unload and achieve energy saving of the hydraulic system.

[0054] During the boom lifting process, if the pressure oil at the oil inlet of the boom control valve 310 is higher than the set pressure of the relief valve 160 and is unloaded, the hydraulic oil acting on one end of the conversion valve 200 (the second chamber cls) on the load sensing oil channel ls is unloaded, and the other end of the conversion valve 200 (the first chamber csl) is connected to the first oil circuit, and the pressure is higher than the second chamber cls, so that the conversion valve 200 is switched to a closed state, and the working pump 101 is unloaded, so that the boom cylinder 301 can achieve energy saving in the hydraulic system when operating at high pressure and low flow.

[0055] Similarly, after the engine is started, the steering system is not turned; the pilot valve 105 is operated, such as the boom lever is operated to descend, the second pilot oil inlet xB2 enters the pilot oil, and the boom control valve 310 is controlled to be in the second working position, that is, Figure 2 In the right position, the oil of the steering pump 103 enters the large and small chambers of the boom cylinder 301 through the boom control valve 310; the hydraulic oil in the large chamber of the boom cylinder 301 enters the boom control valve 310 and flows back to the first oil return passage T1, and flows back to the oil tank 107 through the back pressure valve 410. At the same time, part of the oil at the oil inlet of the boom control valve 310 enters the load sensing oil passage ls through the shuttle valve 120, and is connected to the load sensing oil port LS.

[0056] Part of the pressure oil entering the load sensing oil channel ls is connected to the system shuttle valve 109 through the load sensing oil port LS, and acts on the spring chamber of the compensator 104 of the steering pump 103 through the x oil channel. The displacement of the steering pump 103 is increased to meet the flow demand of the hydraulic system of the execution module.

[0057] The pressure oil that enters the load sensing oil passage ls, and the other part enters the conversion valve 200 to control the conduction or closing of the conversion valve 200. If the pressure difference between the first chamber csl and the second chamber cls is less than or equal to the preset spring pressure set by the conversion valve 200, the spring is located in the second chamber cls, the conversion valve 200 remains open, and the oil of the working pump 101 merges with the oil of the steering pump 103 through the conversion valve 200 to increase the flow rate to meet the working needs of the execution module, so as to speed up the descent of the execution module boom. If the pressure difference between the first chamber csl and the second chamber cls is greater than the preset spring thrust set by the conversion valve 200, the conversion valve 200 is closed, the working pump 101 is unloaded, the flow output is reduced, and energy saving is achieved.

[0058] When the operator controls the boom to descend in a micro-motion manner, that is, the hydraulic oil at the oil inlet of the boom control valve 310 enters the first chamber csl, it can be understood that the load oil enters the first chamber csl through the P2 oil channel. If the pressure difference between the first chamber csl and the second chamber cls is greater than the preset pressure set by the conversion valve 200, that is, the preset spring thrust, the conversion valve 200 switches to a closed state, and the oil from the working pump 101 returns after passing through the conversion valve 200, thereby controlling the unloading of the working pump 101 and realizing energy saving of the hydraulic system.

[0059] During the boom lowering process, if the pressure of the hydraulic oil entering the load sensing oil passage 1s from the oil inlet of the boom control valve 310 through the shuttle valve 120 is higher than the set pressure of the relief valve 160 and is unloaded, the hydraulic oil acting on one end of the conversion valve 200 (the second chamber cls) on the load sensing oil passage 1s is unloaded, and the other end of the conversion valve 200 (the first chamber csl) is connected to the first oil circuit, and the pressure is higher than the second chamber cls, so that the conversion valve 200 is switched to a closed state, and the working pump 101 is unloaded, so that the boom cylinder 301 can achieve energy saving in the hydraulic system when operating at high pressure and low flow.

[0060] During the boom lowering process, a vacuum occurs in the small chamber of the boom cylinder 301, and the floating oil replenishing valve 140 replenishes oil to the small chamber of the boom cylinder 301 to prevent the small chamber of the boom cylinder 301 from being vacuumed and burning the seal. In addition, during the boom lowering process, the floating oil replenishing valve 140 can also keep the boom in a floating state, which is convenient for executing the moving operation of the module and improving the operation efficiency.

[0061] The fourth working condition: after the engine is started, the steering system is not turned; the pilot valve 105 is operated, such as operating the bucket lever to close the bucket, the third pilot oil inlet xA1 enters the pilot oil, and the bucket control valve 350 is controlled to be in the first working position, that is, Figure 2 In the left position, the oil of the steering pump 103 enters the large chamber of the bucket cylinder 303 through the bucket control valve 350; the hydraulic oil in the small chamber of the bucket cylinder 303 enters the bucket control valve 350 and flows back to the oil tank 107. At the same time, part of the oil at the oil inlet of the bucket control valve 350 enters the load sensing oil passage ls through the shuttle valve 120 and communicates with the load sensing oil port LS.

[0062] A part of the pressure oil entering the load sensing oil passage ls is connected to the system shuttle valve 109 through the load sensing oil port LS, and acts on the spring chamber of the compensator 104 of the steering pump 103 through the x oil passage, and the displacement of the steering pump 103 is increased to meet the flow demand of the hydraulic system of the execution module. The other part of the pressure oil entering the load sensing oil passage ls enters the second chamber cls of the conversion valve 200 to control the conduction or closing of the conversion valve 200. If the difference between the oil pressure of the hydraulic oil in the first chamber csl and the oil pressure of the second chamber cls is less than or equal to the preset spring pressure set by the conversion valve 200, the conversion valve 200 remains in the open state, and the oil of the working pump 101 merges with the oil of the steering pump 103 through the conversion valve 200, increasing the flow rate to meet the working needs of the execution module, so as to speed up the execution module to turn and retract the bucket. If the oil pressure difference between the hydraulic oil in the first chamber csl and the oil pressure in the second chamber cls is greater than the preset spring pressure set by the conversion valve 200, the conversion valve 200 is closed, the working pump 101 is unloaded, the flow output is reduced, and energy saving is achieved.

[0063] It can be understood that when the operator uses micro-motion to control the bucket retracting state, the hydraulic oil entering the bucket control valve 350 enters the first chamber csl through the P2 oil channel. If the oil pressure difference between the hydraulic oil in the first chamber csl and the oil pressure in the second chamber cls is greater than the preset spring pressure set by the conversion valve 200, the conversion valve 200 switches to a closed state, and the incoming oil of the working pump 101 returns after passing through the conversion valve 200, thereby controlling the working pump 101 to unload and achieve energy saving of the hydraulic system.

[0064] During the bucket turning and retracting process, if the pressure oil at the oil inlet of the bucket control valve 350 is higher than the set pressure of the relief valve 160 and is unloaded, the hydraulic oil acting on one end of the conversion valve 200 (the second chamber cls) on the load sensing oil channel ls is unloaded, and the other end of the conversion valve 200 (the first chamber csl) is connected to the first oil circuit, and the pressure is higher than the second chamber cls, so that the conversion valve 200 is switched to the closed state, and the working pump 101 is unloaded, so that the bucket cylinder 303 can achieve energy saving in the hydraulic system when operating at high pressure and small flow.

[0065] Similarly, after the engine is started, the steering system is not turned; the pilot valve 105 is operated, such as operating the bucket to unload, the fourth pilot oil inlet xB1 enters the pilot oil, and the bucket control valve 350 is controlled to be in the second working position, that is, Figure 2 In the right position, the oil of the steering pump 103 enters the large and small chambers of the bucket cylinder 303 through the bucket control valve 350; the hydraulic oil in the large chamber of the bucket cylinder 303 enters the bucket control valve 350 and flows back to the first oil return passage T1, and flows back to the oil tank 107 through the back pressure valve 410. At the same time, part of the oil at the oil inlet of the bucket control valve 350 enters the load sensing oil passage ls through the shuttle valve 120, and is connected to the load sensing oil port LS.

[0066] Part of the pressure oil entering the load sensing oil channel ls is connected to the system shuttle valve 109 through the load sensing oil port LS, and acts on the spring chamber of the compensator 104 of the steering pump 103 through the x oil channel. The displacement of the steering pump 103 is increased to meet the flow demand of the hydraulic system of the execution module.

[0067] The pressure oil that enters the load sensing oil passage ls, and the other part enters the second chamber cls of the conversion valve 200, controls the conduction or closing of the conversion valve 200. If the difference between the oil pressure of the hydraulic oil in the first chamber csl and the oil pressure of the second chamber cls is less than or equal to the preset spring pressure set by the conversion valve 200, the conversion valve 200 remains open, and the oil of the working pump 101 merges with the oil of the steering pump 103 through the conversion valve 200, increasing the flow rate to meet the working needs of the execution module, so as to speed up the execution module to unload the bucket. If the difference between the oil pressure of the hydraulic oil in the first chamber csl and the oil pressure of the second chamber cls is greater than the preset spring pressure set by the conversion valve 200, the conversion valve 200 is closed, the working pump 101 is unloaded, the flow output is reduced, and energy saving is achieved.

[0068] When the operator controls the bucket unloading state by micro-movement, that is, the hydraulic oil pressure entering the load sensing oil channel ls from the oil inlet of the bucket control valve 350 is relatively large. If the oil pressure difference between the hydraulic oil in the first chamber csl and the oil pressure in the second chamber cls is greater than the preset spring pressure set by the conversion valve 200, the conversion valve 200 switches to the closed state, and the incoming oil of the working pump 101 returns after passing through the conversion valve 200, thereby controlling the working pump 101 to unload and realize energy saving of the hydraulic system.

[0069] During the bucket unloading process, if the pressure of the hydraulic oil entering the load sensing oil passage 1s from the oil inlet of the bucket control valve 350 through the shuttle valve 120 is higher than the set pressure of the relief valve 160 and unloads, the hydraulic oil acting on one end of the conversion valve 200 (the second chamber cls) on the load sensing oil passage 1s is unloaded, and the other end of the conversion valve 200 (the first chamber csl) is connected to the first oil circuit, and the pressure is higher than the second chamber cls, so that the conversion valve 200 is switched to the closed state, and the working pump 101 is unloaded, so that the bucket cylinder 303 can achieve energy saving in the hydraulic system when operating at high pressure and small flow.

[0070] During the bucket unloading process, a vacuum occurs in the small cavity of the bucket cylinder 303 , and the bucket oil replenishing valve 131 replenishes oil to the small cavity of the bucket cylinder 303 to prevent a vacuum from occurring in the small cavity of the boom cylinder 301 and thus burning the seal.

[0071] It should be noted that the hydraulic control system further includes a pressure reducing valve 460, which is arranged on the control oil circuit between the pilot valve 105 and the large chamber of the actuator oil cylinder. In this embodiment, the pressure reducing valve 460 is arranged on the control oil circuit between the third pilot oil inlet xA1 and the large chamber of the bucket oil cylinder 303, which can realize the combined operation of the boom and the bucket, and the bucket filling rate is high, so the operation efficiency is high, which greatly reduces the operation labor intensity of the driver.

[0072] This embodiment also provides a loader, including the above-mentioned hydraulic control system, which can operate the boom and bucket operations, has high execution efficiency, high hydraulic energy saving efficiency, and can realize the function of automatic unloading or confluence of the working pump 101 when the execution module is in micro-motion state and full-speed motion state, optimize the flow distribution, and realize energy saving of the hydraulic system. It can also realize the hydraulic system to work with high pressure and small flow, and low pressure and large flow, with significant energy saving effect and good economic benefits. And the single variable hybrid hydraulic system is adopted, and the manufacturing cost is lower than that of the dual variable hydraulic system.

[0073] In summary, the hydraulic control system and loader provided by the embodiments of the present invention have the following beneficial effects:

[0074] The hydraulic control system provided by the embodiment of the present invention is suitable for engineering machinery such as loaders, and can realize the function of automatic unloading or confluence of the working pump 101 when the execution module is in micro-motion state and full-speed motion state, optimize the distribution of flow, and realize energy saving of the hydraulic system. It can also realize high-pressure and small-flow operation of the hydraulic system, and low-pressure and large-flow operation, with significant energy saving effect. The displacement of the steering pump 103 is automatically adjusted during the operation process to improve the operation efficiency and achieve significant energy saving effect. In addition, an oil replenishment valve is provided to replenish the small chamber of the execution cylinder with oil to avoid empty suction. The setting of the floating oil replenishment valve 140 can prevent the boom from colliding with the ground or obstacles after descending during the operation. The rapid descent valve 150 can speed up the descent of the boom and improve the operation efficiency. In addition, the floating control valve 130, the bucket oil replenishment valve 131 and the floating oil replenishment valve 140 are arranged together to optimize the pipeline layout, improve the operation efficiency, and have high energy saving efficiency.

[0075] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A hydraulic control system, characterized in that: It includes a working pump, a steering pump, a pilot valve, a multi-way valve and an execution module, the multi-way valve includes a conversion valve and a working valve group, the steering pump is connected to the working valve group, a first oil circuit is formed between the steering pump and the working valve group, the working pump is connected to the working valve group, a second oil circuit is formed between the working pump and the working valve group, the conversion valve is arranged on the second oil circuit, and the working valve group is connected to the execution module; The pilot valve is connected to the working valve group; the pilot valve is used to control the working valve group to switch to a working state, the conversion valve is used to cut off or conduct according to the working state of the working valve group, the conversion valve is used to cut off the second oil circuit to achieve pressure relief, and the conversion valve is used to conduct the second oil circuit to merge the first oil circuit and the second oil circuit; The execution module includes an execution oil cylinder, the working valve group includes a first control end, a second control end, a first working position, a second working position and a third working position, the first control end and the second control end are respectively connected to the pilot valve, the pilot valve is connected to the first control end, the working valve group is in the first working position, the working valve group is connected to the large chamber of the execution oil cylinder, and the large chamber of the execution oil cylinder is filled with oil; the pilot valve is connected to the second control end, the working valve group is in the second working position, the working valve group is connected to the small chamber of the execution oil cylinder, and the small chamber of the execution oil cylinder is filled with oil; There is no conduction between the pilot valve and the working valve group, the working valve group is in the third working position, and the oil circuit between the working valve group and the actuator cylinder is cut off; It also includes: a priority valve and a steering gear, wherein the oil inlet of the priority valve is connected to the steering pump, and the oil outlet is connected to the working valve group, that is, the oil output by the steering pump enters the second oil inlet of the multi-way valve through the priority valve, and the steering gear is connected to the priority valve, and is used for when the working valve group is in the third working position, a part of the oil of the priority valve enters the second chamber of the conversion valve, controls the conversion valve to be in the state of cut-off unloading, and the other part of the oil returns through the steering gear, so as to achieve system energy saving; It also includes an oil replenishment valve and a back pressure valve, the working valve group is in the second working position, the return oil of the working valve group enters the first oil return oil passage, the first oil return oil passage is connected to the oil tank through the back pressure valve; the oil inlet of the oil replenishment valve is connected to the first oil return oil passage, and the oil outlet is connected to the small chamber of the actuator cylinder; It also includes a floating oil replenishing valve, the working valve group is in the second working position, the pilot valve is connected to the control port of the floating oil replenishing valve, the oil outlet of the floating oil replenishing valve is connected to the first oil return oil channel, the floating oil replenishing valve is connected to the small chamber of the actuator cylinder, and the first oil return oil channel is connected to the small chamber of the actuator cylinder through the floating oil replenishing valve.

2. The hydraulic control system according to claim 1, characterized in that: The load sensing oil port of the working valve group is communicated with the compensator of the steering pump to adjust the displacement of the steering pump.

3. The hydraulic control system according to claim 1, characterized in that: The working valve group is in the first working position or the second working position, and the working valve group is connected to the first chamber of the conversion valve. If the oil pressure difference between the hydraulic oil entering the first chamber and the oil pressure of the load is less than or equal to the preset pressure, the conversion valve is in a conducting state, and the working pump is connected to the working valve group through the conversion valve; if the oil pressure difference between the hydraulic oil entering the first chamber and the oil pressure of the load is greater than the preset pressure, the conversion valve is in a cut-off state, and the oil at the outlet of the working pump enters the oil return channel of the multi-way valve through the conversion valve and then returns to the oil tank.

4. The hydraulic control system according to claim 3, characterized in that: It also includes a relief valve, a high-pressure end of the relief valve is connected to the working valve group, and the other end is connected to the oil tank; the second chamber of the conversion valve is connected to the high-pressure end of the relief valve, if the oil pressure of the working valve group is higher than the pressure set by the relief valve, the hydraulic oil of the working valve group is depressurized through the relief valve, and the oil pressure of the second chamber is depressurized to put the conversion valve in a cut-off state, and the oil at the outlet of the working pump enters the oil return channel of the multi-way valve through the conversion valve and then returns to the oil tank.

5. The hydraulic control system according to claim 1, characterized in that: It also includes a rapid descending valve, the working valve group is in the second working position, and the control port of the rapid descending valve is connected to the pilot valve; The oil entering the control port of the rapid descent valve from the pilot valve drives the rapid descent valve to communicate with the first oil return passage, so that the large chamber of the actuator cylinder is communicated with the oil tank.

6. The hydraulic control system according to any one of claims 1 to 5, characterized in that: It also includes a shuttle valve, the working valve group is connected to the shuttle valve, the shuttle valve is connected to the conversion valve, and the shuttle valve is connected to the steering pump through the load sensing oil port of the working valve group.

7. The hydraulic control system according to any one of claims 1 to 5, characterized in that: It also includes a pressure reducing valve, which is arranged on the control oil circuit between the pilot valve and the large chamber of the actuator oil cylinder.

8. A loader, characterized in that: The hydraulic control system comprises the hydraulic control system according to any one of claims 1 to 7.

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