Hydraulic system and engineering machinery

Abstract

The utility model relates to a hydraulic system, which is used for engineering machinery and comprises an oil tank, a first actuating mechanism oil cylinder, a second actuating mechanism oil cylinder, a first oil pump, a second oil pump and a working valve group, the working valve group comprises a first reversing valve used for the first actuating mechanism oil cylinder and a second reversing valve used for the second actuating mechanism oil cylinder, the first reversing valve is provided with a working position and a middle position, and when the first reversing valve is located at the working position, pressure oil extracted from the oil tank by the first oil pump is supplied to the first actuating mechanism oil cylinder through the first reversing valve; the second reversing valve is provided with a working position and a middle position, and when the second reversing valve is located at the working position, pressure oil pumped by the second oil pump from the oil tank is supplied to the second actuating mechanism oil cylinder through the second reversing valve; the hydraulic system is characterized in that when the first reversing valve is in the middle position, pressure oil from the first reversing valve and pressure oil from the second oil pump are converged through the one-way valve and then are supplied to the second reversing valve. The utility model further relates to engineering machinery with the hydraulic system.

Description

Technical Field

[0001] The utility model relates to the technical field of hydraulic systems, in particular to a hydraulic system for engineering machinery and engineering machinery with the hydraulic system. Background Art

[0002] The working hydraulic systems of traditional construction machinery, such as bulldozers, are mostly single-pump open-type quantitative systems, in which a single pump serves as the hydraulic oil source to realize the movements of the lifting cylinder and the tilting cylinder. However, the lifting action requires the hydraulic system to provide a large flow rate, while the system requires a smaller flow rate when performing the tilting action. At this time, the single-pump open-type quantitative system will have excess flow high-pressure overflow when performing the tilting action, which not only increases fuel consumption but also shortens the system life.

[0003] Therefore, the present invention is dedicated to one or more improvements to the prior art. Utility Model Content

[0004] In view of the defects of the prior art, the utility model proposes an improved technology for a hydraulic system of engineering machinery, which enables the hydraulic system to save oil consumption and increase the life of the system.

[0005] According to one aspect of the utility model, a hydraulic system for engineering machinery is provided, comprising an oil tank, a first actuator cylinder, a second actuator cylinder, a first oil pump, a second oil pump and a working valve group, the working valve group comprising a first reversing valve for the first actuator cylinder and a second reversing valve for the second actuator cylinder, wherein the first reversing valve has a working position and a middle position, and when it is in the working position, the pressure oil drawn from the oil tank by the first oil pump is supplied to the first actuator cylinder via the first reversing valve; the second reversing valve has a working position and a middle position, and when it is in the working position, the pressure oil drawn from the oil tank by the second oil pump is supplied to the second actuator cylinder via the second reversing valve; it is characterized in that when the first reversing valve is in the middle position, the pressure oil from the first reversing valve merges with the pressure oil from the second oil pump via a one-way valve and then is supplied to the second reversing valve.

[0006] Advantageously, the first actuator cylinder is a tilt cylinder and the second actuator cylinder is a lift cylinder.

[0007] Advantageously, the first reversing valve is a three-position six-way valve; and / or the second reversing valve is a four-position six-way valve.

[0008] Advantageously, the hydraulic system comprises a control device for connecting with the first reversing valve and the second reversing valve to send control instructions to the first reversing valve and the second reversing valve, and the control device comprises a pilot valve.

[0009] Advantageously, the first oil inlet and the first oil outlet of the first reversing valve are connected when in the middle position, a one-way valve is provided at the second oil inlet of the first reversing valve, the first working oil port of the first reversing valve is connected to the rodless chamber of the roll cylinder, the second working oil port of the first reversing valve is connected to the rod chamber of the roll cylinder, the second oil outlet of the first reversing valve is connected to the return oil port of the working valve group through the oil circuit, a first bypass oil circuit is provided between the first working oil port and the second oil outlet of the first reversing valve, and a first oil replenishing valve is provided in the first bypass oil circuit.

[0010] Advantageously, the first oil inlet and the first oil outlet of the second reversing valve are connected when they are in the middle position, a one-way valve is provided at the second oil inlet of the second reversing valve, the first working oil port of the second reversing valve is connected to the rodless chamber of the lifting cylinder, the second working oil port of the second reversing valve is connected to the rod chamber of the lifting cylinder, the second oil outlet of the second reversing valve is connected to the oil return port of the working valve group through the oil circuit, a second bypass oil circuit is provided between the first working oil port and the second oil outlet of the second reversing valve, and a second oil replenishing valve is provided in the second bypass oil circuit.

[0011] Advantageously, a safety valve is provided between the confluence point of the pressure oil from the first reversing valve and the pressure oil from the second oil pump and the oil return port of the working valve group.

[0012] Advantageously, the displacement of the first oil pump is smaller than the displacement of the second oil pump.

[0013] According to another aspect of the utility model, there is provided an engineering machine, characterized in that the engineering machine comprises the above-mentioned hydraulic system.

[0014] Advantageously, the construction machine is a bulldozer or a loader.

[0015] According to the utility model, the hydraulic system uses two pump sources, and according to the specific needs of the actuator cylinder, the two oil pumps are used differently, especially when performing lifting operations, the confluence of the two oil pumps can be used to achieve rapid lifting of the machine. In this way, the machine can be ensured to move accurately and quickly with the lowest possible fuel consumption, and higher control flexibility and longer system life can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Exemplary embodiments of the present invention are described with reference to the accompanying drawings, in which:

[0017] Figure 1 is a schematic diagram of a hydraulic system for engineering machinery of the utility model; and

[0018] Figure 2 It is a schematic diagram of a working valve group of a hydraulic system of the utility model.

[0019] Reference numerals:

[0020] 1- hydraulic system; 142- second reversing valve;

[0021] TA-oil tank; 141a-first one-way valve;

[0022] PP1-first oil pump; 140-second one-way valve;

[0023] PP2-second oil pump; 142a-third one-way valve;

[0024] E-engine; 143-first oil supply valve;

[0025] 11-first actuator oil cylinder; 144-second oil replenishing valve;

[0026] 110y-rod of the first actuator cylinder PL1-first bypass oil circuit;

[0027] Cavity; PL2-second bypass oil circuit;

[0028] 110n- first actuator cylinder without 145- first safety valve;

[0029] Rod chamber; 146 - second safety valve;

[0030] 12- Second actuator cylinder; O- Confluence point;

[0031] 121-the first lifting cylinder; P1-the first oil inlet of the working valve group;

[0032] 121y-rod chamber of the first lifting cylinder; P2-second oil inlet of the working valve group;

[0033] 121n-rodless chamber of the first lifting cylinder; T1-first oil return port of the working valve group;

[0034] 122-the second lifting cylinder; T2-the second oil return port of the working valve group;

[0035] 122y-rod chamber of the second lifting cylinder; 20-first oil inlet of the first reversing valve;

[0036] 122n - the rodless chamber of the second lifting cylinder; 21 - the second oil inlet of the first reversing valve;

[0037] 13-control device; 26-first oil outlet of the first reversing valve;

[0038] 14-working valve group; 23-second oil outlet of the first reversing valve;

[0039] 141 - a first reversing valve; 24 - a first working oil port of the first reversing valve; 33- the second oil outlet of the second reversing valve;

[0040] 25 - the second working oil port of the first reversing valve; 34 - the first working oil port of the second reversing valve;

[0041] 30 - the first oil inlet of the second reversing valve; 35 - the second working oil port of the second reversing valve. 31 - a second oil inlet of the second reversing valve;

[0042] 36-the first oil outlet of the second reversing valve;

[0043] The accompanying drawings are only schematic and not necessarily drawn to scale, and they only show those parts necessary to illustrate the utility model, and other parts are omitted or only mentioned. That is, in addition to the parts shown in the accompanying drawings, the utility model may also include other parts. DETAILED DESCRIPTION

[0044] The technical solution of the utility model is described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth so that the technical personnel in the relevant technical field can more fully understand the utility model. However, it is obvious to the technical personnel in the relevant technical field that the implementation of the utility model may not have some of these specific details. In addition, it should be understood that the utility model is not limited to the specific embodiments introduced. On the contrary, it can be considered to implement the utility model with any combination of the following features and elements, whether or not they relate to different embodiments.

[0045] Figure 1 The utility model shows a hydraulic system 1 for engineering machinery. The hydraulic system 1 includes an oil tank TA, a first actuator cylinder 11, a second actuator cylinder 12, a first oil pump PP1, a second oil pump PP2, a control device 13, and a working valve group 14. The amount of oil required when the first actuator is actuated is less than the amount of oil required when the second actuator is actuated. The working valve group 14 includes a first reversing valve 141 for the first actuator cylinder 11 and a second reversing valve 142 for the second actuator cylinder 12. The control device 13 is connected to the first reversing valve 141 and the second reversing valve 142, respectively, to send control instructions to the first reversing valve and the second reversing valve.

[0046] like Figure 1 As shown, the first oil pump PP1 and the second oil pump PP2 are driven to rotate by the engine E. The oil suction ports of the first oil pump and the second oil pump are connected to the oil tank TA. The oil outlets of the first oil pump and the second oil pump are connected to the first oil inlet P1 and the second oil inlet P2 of the working valve group 14 respectively.

[0047] Combination Figure 1 and Figure 2As shown, the first oil inlet P1 is connected to the first oil inlet 20 of the first reversing valve 141, and is connected to the second oil inlet 21 of the first reversing valve through the first check valve 141a, the first oil outlet 26 of the first reversing valve is connected to the inlet of the second check valve 140, and the second oil outlet 23 of the first reversing valve is connected to the first oil return port T1 of the working valve group. In the middle position of the first reversing valve, the first oil inlet 20 and the first oil outlet 26 are connected. In the illustrated embodiment, the first working oil port 24 of the first reversing valve 141 is connected to the rodless chamber 110n of the first actuator cylinder 11. The second working oil port 25 of the first reversing valve 141 is connected to the rod chamber 110y of the first actuator cylinder 11. A first bypass oil path PL1 is provided between the first working oil port 24 and the second oil outlet 23 of the first reversing valve, and a first oil replenishing valve 143 is provided in the first bypass oil path.

[0048] The outlet of the second check valve 140 is connected to the second oil inlet P2 of the working valve group, and is respectively connected to the first oil inlet 30 and the second oil inlet 31 of the second reversing valve 142. A third check valve 142a is provided at the second oil inlet 31. The inlet of the third check valve 142a is connected to the outlet of the second check valve 140, and the outlet of the third check valve 142a is connected to the second oil inlet 31 of the second reversing valve 142. The first oil outlet 36 of the second reversing valve 142 is connected to the second oil return port T2 of the working valve group. The second oil outlet 33 of the second reversing valve 142 is connected to the first oil return port T1 of the working valve group. In the middle position of the second reversing valve 142, the first oil inlet 30 is connected to the first oil outlet 36. In the illustrated embodiment, the first working oil port 34 of the second reversing valve 142 is connected to the rodless chamber of the second actuator cylinder 12, and the second working oil port 35 of the second reversing valve 142 is connected to the rod chamber of the second actuator cylinder 12. A second bypass oil passage PL2 is provided between the first working oil port 34 and the second oil outlet port 33 of the second switching valve 142 , and a second oil replenishment valve 144 is provided in the second bypass oil passage.

[0049] The first oil return port T1 and the second oil return port T2 of the working valve group 14 are communicated with the oil tank TA.

[0050] When the first reversing valve 141 is in the middle position, the pressure oil from the first reversing valve merges with the pressure oil from the second oil pump at the confluence point O through the second one-way valve 140, and is then supplied to the second reversing valve 142, and flows into the second actuator cylinder 12 or returns to the oil tank through the second reversing valve.

[0051] In the illustrated embodiment, a first safety valve 145 is provided between the first oil inlet P1 and the first oil return port T1 of the working valve group 14. A second safety valve 146 is provided between the confluence point O and the first oil return port T1. The first safety valve 145 and the second safety valve 146 are, for example, overflow valves.

[0052] The working valve group 14 can be implemented as a valve block that integrates the first reversing valve 141, the second reversing valve 142, the first safety valve 145, the second safety valve 146, the first oil replenishing valve 143, the second oil replenishing valve 144, the first check valve 141a, the second check valve 140 and the third check valve 142a as well as the oil circuits connecting them.

[0053] In the illustrated embodiment, the hydraulic system 1 is a hydraulic system of a bulldozer or an excavator. The first actuator cylinder 11 is a tilt cylinder. The second actuator cylinder 12 is a lift cylinder. The first reversing valve is a three-position six-way valve. The second reversing valve is a four-position six-way valve. The control device 13 includes a pressure control valve, such as a pilot valve. The displacement of the first oil pump is smaller than the displacement of the second oil pump.

[0054] In the illustrated embodiment, the second actuator cylinder includes two lifting cylinders. The first working oil port 34 of the second reversing valve 142 is respectively connected to the rodless chamber 121n of the first lifting cylinder 121 and the rodless chamber 122n of the second lifting cylinder 122. The second working oil port 35 of the second reversing valve 142 is respectively connected to the rod chamber 121y of the first lifting cylinder 121 and the rod chamber 122y of the second lifting cylinder 122. Although the second actuator cylinder includes two lifting cylinders in the figure, it can be understood that the number and arrangement of the lifting cylinders are not limited to the illustrated embodiment.

[0055] Combine the following Figure 1 The working principle of the hydraulic system of the utility model is explained.

[0056] When performing the roll operation, the control device 13 controls the valve core of the first reversing valve 141 to slide, so that the first reversing valve enters the left position shown in the figure. At this time, the hydraulic oil from the first oil pump PP1 enters the first oil inlet P1 of the working valve group, opens the first check valve 141a under the action of pressure, and the pressure oil enters the rod chamber of the roll cylinder from the second oil inlet 21 through the second working oil port 25, pushing the piston to move to the right, and then performing the first roll action. The hydraulic oil discharged from the rodless chamber of the roll cylinder returns to the oil tank through the first working oil port 24 and the second oil outlet 23. In response to the change demand of the roll action, the control device 13 can switch the first reversing valve 141 to the right position shown in the figure. At this time, the hydraulic oil from the first oil pump flows in through the first oil inlet P1, opens the first check valve 141a, enters the rodless chamber of the roll cylinder through the second oil inlet 21 and the first working oil port 24, pushes the piston to move to the left, and performs the second roll action opposite to the first roll action. The hydraulic oil flowing out of the rod chamber flows through the second working oil port 25 and the second oil outlet 23 to the return oil port of the working valve group, and then returns to the oil tank. When executing the second tilting action, due to the gravity of the actuator itself, the piston moves rapidly, resulting in negative pressure in the rodless chamber of the tilt cylinder. The oil pressure at the outlet of the first oil replenishing valve 143 will be instantaneously lower than the oil pressure at the inlet of the first oil replenishing valve 143. The first oil replenishing valve 143 is pushed open, and the supplementary oil flow to the rodless chamber of the tilt cylinder is obtained from the return oil flow path. The specified tilting action of the bulldozer shovel can be achieved by supplying oil to the tilt cylinder through the first oil pump. Generally, a smaller displacement oil pump is used as the first oil pump, thereby achieving precise control and precise positioning of the bulldozer shovel angle.

[0057] For bulldozers, lifting and tilting operations are usually performed separately. When performing lifting and lowering operations, the first reversing valve 141 is in the middle position, and the valve core of the second reversing valve moves into the left position shown in the figure to perform lifting operations. The pressure oil from the second oil pump PP2 flows into the working valve group 14 from the second oil inlet P2. The first oil inlet 20 and the first oil outlet 26 of the first reversing valve 141 in the middle position are connected, so the pressure oil from the first oil pump enters through the first oil inlet P1 and flows through the first reversing valve and the second one-way valve 140, merges with the pressure oil from the second oil pump and flows to the second reversing valve 142. The merged oil flows through the third one-way valve 142a into the second oil inlet 31, and flows into the rod chamber of the lifting cylinder through the second working oil port 35, pushing the piston to move to the right to perform the lifting operation. Similarly, when the second check valve 142 moves to the right position as shown in the figure, the oil flows from the first oil pump PP1 and the second oil pump PP2 merge and enter the second oil inlet 31 through the third check valve 142a, flow to the first working oil port 34, and then flow into the rodless chamber of the lifting cylinder to perform the falling operation. Due to the gravity of the actuator itself, the piston rod of the lifting cylinder moves too fast, and the rodless chamber of the lifting cylinder will have an instantaneous negative pressure. At this time, the second oil replenishment valve 144 opens, and part of the oil flow is extracted from the return oil flow path as a replenishment oil flow to supply to the rodless chamber of the lifting cylinder.

[0058] In the embodiment shown, the second reversing valve is a four-position six-way valve, which includes the right second position at the end in addition to the left position, the middle position, and the right first position. In the right second position of the second reversing valve, the first oil inlet 30 is connected to the second oil outlet 33, and the first oil outlet 36 is connected to the first working oil port 34, thereby keeping the lifting cylinder in a floating position. This floating position is conducive to the passive lifting of the bulldozer and ensures the safety of the hydraulic system.

[0059] Therefore, the hydraulic system according to the utility model utilizes the confluence of the two oil pumps to perform the lifting operation (i.e., the lifting or lowering action of the bulldozer blade). Since the first oil pump and the second oil pump jointly supply oil, a larger flow rate is provided to the hydraulic system, so that the bulldozer blade can be quickly lifted or lowered with less oil consumption in the system.

[0060] When the control device sends control instructions to the first reversing valve and the second reversing valve at the same time, for example, when instructing to perform a compound action operation, the first oil pump supplies oil to the roll oil cylinder and the second oil pump supplies oil to the lift oil cylinder. At this time, the actions do not interfere with each other.

[0061] Therefore, the hydraulic system for a bulldozer according to the utility model advantageously adopts two oil pumps and advantageously utilizes a small-displacement first oil pump to achieve precise control of the dozer angle and utilizes the confluence of the first oil pump and the second oil pump to achieve rapid lifting and lowering of the dozer, thereby reducing oil consumption and extending system life.

[0062] Industrial Applicability

[0063] In order to better understand the present invention, Figure 1 The hydraulic system shown is used as an example to illustrate the advantages of the present invention.

[0064] The hydraulic system of the utility model adopts two pump sources, a first oil pump and a second oil pump. The first oil pump with a small displacement supplies oil to the roll cylinder when the first reversing valve is in the left position or the right position to perform the roll action.

[0065] The second oil pump with a large displacement supplies oil to the lifting cylinder when the second reversing valve is in the left position or the right position. In the hydraulic system of the utility model, the middle oil outlet of the first reversing valve is connected to the oil inlet of the second reversing valve via the second one-way valve, so that when the first reversing valve is in the middle position, the pressure oil from the first oil pump and the pressure oil from the second oil pump can be combined and supplied to the lifting cylinder. The second one-way valve also prevents the pressure oil from the second oil pump from flowing into the first reversing valve and the first oil pump, ensuring the safety of the first oil pump. As a result, the hydraulic system of the utility model can greatly reduce the total oil consumption of the system and extend the life of the system.

[0066] In addition, the working valve group of the entire hydraulic system has a simple structure and is flexible and convenient to control. Therefore, the hydraulic system according to the utility model is suitable for a wide range of applications.

[0067] The hydraulic system according to the utility model can be used in engineering machinery such as a bulldozer or a loader to achieve desired work and operation, and is also suitable for other machinery with similar working conditions.

[0068] The above exemplary embodiments have made a clear and complete description of the utility model. It should be understood by those skilled in the art that various other embodiments can be conceived by modifying the disclosed technical solutions without departing from the spirit and scope of the utility model. These embodiments should be understood to fall within the scope of the utility model determined based on the claims and any equivalent technical solutions thereof.

Claims

1. A hydraulic system for engineering machinery, comprising an oil tank, a first actuator cylinder, a second actuator cylinder, a first oil pump, a second oil pump and a working valve group, wherein the working valve group comprises a first reversing valve for the first actuator cylinder and a second reversing valve for the second actuator cylinder, wherein: The first reversing valve has a working position and a middle position. When the first reversing valve is in the working position, the pressure oil drawn from the oil tank by the first oil pump is supplied to the first actuator cylinder via the first reversing valve. The second reversing valve has a working position and a middle position. When the second reversing valve is in the working position, the pressure oil drawn from the oil tank by the second oil pump is supplied to the second actuator cylinder via the second reversing valve. It is characterized in that When the first reversing valve is in the middle position, the pressure oil from the first reversing valve merges with the pressure oil from the second oil pump via the one-way valve and is then supplied to the second reversing valve.

2. The hydraulic system according to claim 1, characterized in that: The first actuator oil cylinder is a tilt oil cylinder, and the second actuator oil cylinder is a lift oil cylinder.

3. The hydraulic system according to claim 2, characterized in that: The first reversing valve is a three-position six-way valve; and / or the second reversing valve is a four-position six-way valve.

4. The hydraulic system according to claim 2, characterized in that: The hydraulic system comprises a control device connected with the first reversing valve and the second reversing valve to send control instructions to the first reversing valve and the second reversing valve, wherein the control device comprises a pilot valve.

5. The hydraulic system according to claim 3, characterized in that: The first oil inlet and the first oil outlet of the first reversing valve are connected when in the middle position, a one-way valve is arranged at the second oil inlet of the first reversing valve, the first working oil port (24) of the first reversing valve is connected to the rodless chamber of the roll cylinder, the second working oil port (25) of the first reversing valve is connected to the rod chamber of the roll cylinder, the second oil outlet (23) of the first reversing valve is connected to the return oil port of the working valve group, a first bypass oil circuit is arranged between the first working oil port and the second oil outlet (23) of the first reversing valve, and a first oil replenishing valve is arranged in the first bypass oil circuit.

6. The hydraulic system according to claim 3, characterized in that: The first oil inlet and the first oil outlet of the second reversing valve are connected when in the middle position, a one-way valve is arranged at the second oil inlet of the second reversing valve, the first working oil port (34) of the second reversing valve is connected to the rodless chamber of the lifting cylinder, the second working oil port (35) of the second reversing valve is connected to the rod chamber of the lifting cylinder, the second oil outlet (33) of the second reversing valve is connected to the return oil port of the working valve group through the oil circuit, a second bypass oil circuit is arranged between the first working oil port and the second oil outlet (33) of the second reversing valve, and a second oil replenishing valve is arranged in the second bypass oil circuit.

7. The hydraulic system according to claim 1, characterized in that: A safety valve is provided between a confluence point of the pressure oil from the first reversing valve and the pressure oil from the second oil pump and an oil return port of the working valve group.

8. The hydraulic system according to any one of claims 1 to 7, characterized in that: The displacement of the first oil pump is smaller than the displacement of the second oil pump.

9. An engineering machine, characterized in that: The construction machine comprises a hydraulic system according to any one of claims 1-8.

10. The construction machine according to claim 9, characterized in that: The engineering machinery is a bulldozer or a loader.

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