Hydraulic system and working machine

Abstract

The present application relates to the technical field of hydraulic pressure, and provides a hydraulic system and a working machine, wherein the hydraulic system comprises a cylinder, a first control valve, a pressure supply device, a main oil path and an oil tank; the oil inlet of the pressure supply device is communicated with the oil tank, and the oil outlet of the pressure supply device is communicated with the first control valve; the first control valve is communicated with the rodless cavity of the cylinder, the oil tank and the main oil path, and the first control valve has a first working position; when the cylinder is retracted, the first control valve is placed in the first working position, and the hydraulic oil in the rodless cavity of the cylinder is returned to the main oil path through the first control valve. The hydraulic system and the working machine provided by the present application can make part of the hydraulic oil in the rodless cavity return to the main oil path when the first control valve is placed in the first working position, so that the potential energy of the boom is converted into the kinetic energy of other devices connected with the main oil path, the utilization rate of the potential energy of the boom is improved, and the waste of energy is effectively prevented.

Description

Technical Field

[0001] This invention relates to the field of hydraulic technology, and in particular to a hydraulic system and a working machine. Background Technology

[0002] With the current trends of electrification and intelligentization, energy saving and fuel consumption reduction have become major research hotspots, and the effective utilization rate of energy has become one of the important indicators for evaluating the advancement of operating machinery. The existing boom potential energy recovery of operating machinery mainly involves recovering the high-pressure oil in the boom from the rodless chamber to the rod chamber, which has a low recovery rate.

[0003] Taking an excavator as an example, it achieves digging and unloading through single or combined actions of the boom, stick, bucket, and swing. The operator operates a pilot handle in the cab to switch the main valve spool, pumping out high-pressure oil to supply various working devices, while simultaneously returning oil from the working devices to the oil tank. Because the excavator's boom and working devices are very heavy, there is a problem of recovering gravitational potential energy during descent. The traditional method is to regenerate high-pressure oil from the rodless chamber to the rod chamber through the boom control valve spool. The area ratio of the rodless chamber to the rod chamber is approximately 2:1. Therefore, during boom descent, even if all the flow in the rodless chamber is regenerated, about 50% of the flow cannot be regenerated and is discharged to the oil tank, causing some potential energy to be converted into heat energy, resulting in waste. Summary of the Invention

[0004] This invention provides a hydraulic system and a working machine to solve the problem that the potential energy recovery rate of the boom of the working machine is low and can only be used for its own purposes when it is lowering.

[0005] This invention provides a hydraulic system, comprising: a cylinder, a first control valve, a pressure supply device, a main oil circuit, and an oil tank;

[0006] The oil inlet of the pressure supply device is connected to the oil tank, and the oil outlet of the pressure supply device is connected to the first control valve;

[0007] The first control valve is connected to the rodless chamber of the cylinder, the oil tank and the main oil circuit, and the first control valve has a first working position;

[0008] When the cylinder retracts, the first control valve is placed in the first working position, and the hydraulic oil in the rodless chamber of the cylinder flows back to the main oil circuit through the first control valve.

[0009] According to a hydraulic system provided by the present invention, the first working position includes a full operating position and a half operating position;

[0010] When the first control valve is in the full operating position, the rodless chamber of the cylinder is connected to the main oil circuit through the first control valve, and the rodless chamber of the cylinder is disconnected from the oil tank. The hydraulic oil in the rodless chamber of the cylinder flows back to the main oil circuit through the first control valve.

[0011] When the first control valve is in the semi-operation position, the rodless chamber of the cylinder is connected to the main oil circuit and the oil tank through the first control valve, and the hydraulic oil in the rodless chamber of the cylinder flows back to the main oil circuit and the oil tank through the first control valve.

[0012] According to a hydraulic system provided by the present invention, the first control valve further has a second working position and a third working position;

[0013] When the cylinder position is maintained, the first control valve is placed in the second working position, and the rodless chamber of the cylinder is simultaneously disconnected from the pressure supply device, the main oil circuit and the oil tank;

[0014] When the cylinder extends, the first control valve is placed in the third working position, the rodless chamber of the cylinder is connected to the pressure supply device and disconnected from the oil tank, and the pressure supply device supplies oil to the rodless chamber of the cylinder through the first control valve.

[0015] According to a hydraulic system provided by the present invention, the first control valve includes:

[0016] The valve body has a valve cavity, and the valve body has a first valve port, a second valve port and a third valve port that are respectively connected to the valve cavity. The first valve port is connected to the oil tank, the second valve port is connected to the pressure supply device and the main oil circuit, and the third valve port is connected to the rodless cavity of the oil cylinder.

[0017] The valve core is provided with a first check valve and a second check valve, and the outlet of the first check valve is connected to the outlet of the second check valve.

[0018] When the first control valve is in the first operating position:

[0019] The third valve port is connected to the second valve port through the first check valve or the second check valve; or, the third valve port is connected to the second valve port and the first valve port through the first check valve or the second check valve.

[0020] A hydraulic system provided by the present invention,

[0021] When the first control valve is in the second working position, the third valve port is disconnected from both the first valve port and the second valve port.

[0022] When the first control valve is placed in the third working position, the first valve port is connected to the inlet of the first check valve, the second valve port is connected to the outlet of the first check valve, and the third valve port is connected to the outlets of the first check valve and the second check valve.

[0023] A hydraulic system provided by the present invention,

[0024] The valve body has a first annular groove, a second annular groove and a third annular groove on the inner wall of the valve cavity. The first annular groove is connected to the first valve port, the second annular groove is connected to the second valve port, and the third annular groove is connected to the third valve port.

[0025] The valve core has a first mounting cavity, a continuous channel and a second mounting cavity connected in sequence on its inner side. The side wall of the valve core has a first through hole communicating with the first mounting cavity, a second through hole communicating with the continuous channel and a third through hole communicating with the second mounting cavity.

[0026] The first check valve is disposed in the first mounting cavity, and the second check valve is disposed in the second mounting cavity, with the first check valve and the second check valve facing each other.

[0027] A hydraulic system according to the present invention further includes:

[0028] The second control valve has a first valve port connected to the rod chamber of the oil cylinder, a second valve port connected to the rodless chamber of the oil cylinder, a third valve port connected to the oil tank, and a fourth valve port connected to the oil supply device.

[0029] The second control valve has a fourth working position, a fifth working position, and a sixth working position;

[0030] When the second control valve is in the fourth working position, the first valve port of the second control valve is connected to the fourth valve port, and the second valve port of the second control valve is connected to the first valve port in one direction.

[0031] When the second control valve is in the fifth working position, the first valve port of the second control valve is connected to the third valve port, and the second valve port of the second control valve is connected to the fourth valve port;

[0032] When the second control valve is in the sixth working position, the first valve port, the second valve port, the third valve port and the fourth valve port of the second control valve are disconnected from each other.

[0033] According to a hydraulic system provided by the present invention, the pressure supply device includes a first oil pump and a second oil pump, wherein the oil outlet of the first oil pump is connected to the second control valve and the main oil circuit, and the oil outlet of the second oil pump is connected to the first control valve and the main oil circuit.

[0034] According to a hydraulic system provided by the present invention, a load holding valve is further included, wherein the load holding valve is connected to the first control valve, the second control valve and the rodless chamber of the cylinder respectively.

[0035] The present invention also provides a working machine, including the above-described hydraulic system.

[0036] The hydraulic system provided by the present invention, by placing the first control valve in the first working position, enables a portion of the hydraulic oil in the rodless chamber to flow back to the main oil circuit when the oil cylinder retracts, thereby converting the potential energy of the boom into the kinetic energy of other devices connected to the main oil circuit, improving the utilization rate of the boom's potential energy and effectively preventing energy waste.

[0037] Furthermore, the working machinery provided by the present invention also possesses the advantages described above due to the hydraulic system described above. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the hydraulic connection structure of a hydraulic system provided by the present invention;

[0040] Figure 2 This is a schematic diagram of the structure of the first control valve in a hydraulic system in the fully operating position of the first working position, provided by the present invention.

[0041] Figure 3 This is a schematic diagram of the structure of a first control valve in a hydraulic system in the second working position, provided by the present invention.

[0042] Figure 4 This is a schematic diagram of the structure of the first control valve in a hydraulic system in the third working position, provided by the present invention.

[0043] Reference numerals: 1. First oil pump; 2. Second oil pump; 3. First control valve; 4. Second annular groove; 5. Oil cylinder; 7. Second control valve; 8. Regeneration passage; 9. Load holding valve; 11. Full operating position; 12. Half operating position; 13. Second working position; 14. Third working position; 15. Fourth working position; 16. Fifth working position; 17. Sixth working position; 18. First annular groove; 19. Third annular groove; 20. Main oil circuit; 21. First external signal; 22. Second external signal; 24. Second through hole; 25. First through hole; 27. First spring cavity; 28. Third through hole; 29. ​​Second spring cavity; 30. Second check valve; 31. First check valve; 32. Continuous passage; 33. Second inlet pipe; 34. First inlet pipe; 51. Rodless cavity; 52. Rod cavity. Detailed Implementation

[0044] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0045] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of 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, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0046] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0047] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0048] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0049] The following is combined with Figures 1 to 4 The hydraulic system described in the embodiments of the present invention, wherein, Figure 1 This is a schematic diagram of the hydraulic connection structure of a hydraulic system provided by the present invention; Figure 2 This is a schematic diagram of the structure of the first control valve 3 in the first working position 11 of a hydraulic system provided by the present invention; Figure 3 This is a schematic diagram of the structure of the first control valve 3 in the second working position 13 in a hydraulic system provided by the present invention; Figure 4 This is a schematic diagram of the structure of the first control valve 3 in the third working position 14 in a hydraulic system provided by the present invention; Figure 2 and Figure 4 The curved arrows in the diagram indicate the direction of hydraulic oil flow.

[0050] According to an embodiment of the present invention, a hydraulic system includes: a cylinder 5, a first control valve 3, a pressure supply device, a main oil circuit 20, and an oil tank. The oil inlet of the pressure supply device is connected to the oil tank, and the oil outlet of the pressure supply device is connected to the first control valve 3. When the pressure supply device is running, it can supply hydraulic oil to the first control valve 3. The first control valve 3 is connected to the rodless chamber 51 of the cylinder 5, the oil tank, and the main oil circuit 20, and has a first working position. When the cylinder 5 retracts, the first control valve 3 is placed in the first working position, and the hydraulic oil in the rodless chamber 51 of the cylinder 5 flows back to the main oil circuit 20 through the first control valve 3.

[0051] In the above scheme, the hydraulic cylinder 5 can be installed on, for example, the boom of an excavator. The retraction process of the hydraulic cylinder 5 is the boom retraction process. During this process, the boom moves from a high position to a low position, and the potential energy of the boom can be converted into the kinetic energy of the hydraulic oil in the rodless chamber 51 through the piston movement of the hydraulic cylinder 5. This kinetic energy can be supplied to the main oil circuit 20 when the first control valve 3 is in the first working position, realizing potential energy recovery and effectively reducing energy waste. It can be understood that the main oil circuit 20 is connected to other working devices in the operating machinery, and the potential energy recovered by the hydraulic cylinder 5 can provide kinetic energy for the operation of other working devices. It is worth noting that during the potential energy recovery process of the hydraulic cylinder 5, oil can also be supplied to other working devices through the pressure supply device. During use, the working pressure of the pressure supply device can be used to determine whether regeneration is needed, or the pressure supply device can be operated based on the return pressure, and the working pressure of the pressure supply device can be adjusted.

[0052] According to an embodiment of the hydraulic system of the present invention, the first operating position includes a full operating position 11 and a half operating position 12.

[0053] When the first control valve 3 is in the full operating position 11, the rodless chamber 51 of the cylinder 5 is connected to the main oil circuit 20 through the first control valve 3, and the rodless chamber 51 of the cylinder 5 is disconnected from the oil tank. The hydraulic oil in the rodless chamber 51 of the cylinder 5 flows back to the main oil circuit 20 through the first control valve 3. This process is to recover all the potential energy of the boom, so as to maximize the recovery and utilization of energy. The "complete recovery" mentioned here refers to the complete recovery under the premise of eliminating unavoidable energy loss. Moreover, the maximization of recovery and utilization is only the maximization compared to the partial return and non-return of hydraulic oil. The energy loss caused by the conversion of other forms of energy also needs to be considered.

[0054] When the first control valve 3 is in the semi-operating position 12, the rodless chamber 51 of the cylinder 5 is connected to the main oil circuit 20 and the oil tank through the first control valve 3. The hydraulic oil in the rodless chamber 51 of the cylinder 5 flows back to the main oil circuit 20 and the oil tank through the first control valve 3. During this process, the hydraulic oil in the rodless chamber 51 of the cylinder 5 partially flows back to the oil tank and partially flows back to the main oil circuit 20 through the first control valve 3. The ratio of the two flows can be flexibly adjusted according to the actual use situation, and no specific limitation is made here.

[0055] In the above scheme, the hydraulic oil recovery method of cylinder 5 can be flexibly adjusted according to actual usage needs, making it more flexible and applicable.

[0056] According to an embodiment of the hydraulic system of the present invention, the first control valve 3 further has a second working position 13 and a third working position 14. Wherein:

[0057] When the cylinder 5 is in the same position, the first control valve 3 is in the second working position 13. The rodless chamber 51 of the cylinder 5 is simultaneously disconnected from the pressure supply device, the main oil circuit 20 and the oil tank. The hydraulic oil in the rodless chamber 51 of the cylinder 5 cannot flow back to the main oil circuit 20 or the oil tank through the first control valve 3, and the hydraulic oil supplied by the pressure supply device cannot be supplied to the rodless chamber 51 of the cylinder 5 through the first control valve 3, thus achieving the sealing of the hydraulic oil in the rodless chamber 51, and the cylinder 5 is held in a fixed position.

[0058] When cylinder 5 extends, the first control valve 3 is placed in the third working position 14. The rodless chamber 51 of cylinder 5 is connected to the pressure supply device and disconnected from the oil tank. The pressure supply device supplies oil to the rodless chamber 51 of cylinder 5 through the first control valve 3, providing power for the extension of cylinder 5. It can be understood that during the extension of cylinder 5, the pressure supply device can also simultaneously supply hydraulic oil to other working devices through the main oil circuit 20.

[0059] In this embodiment of the invention, the first control valve 3 can switch between the first working position, the second working position 13 and the third working position 14 to realize the action control of the extension and holding of the hydraulic cylinder 5, as well as the backflow control of the hydraulic oil in the rodless chamber 51 of the hydraulic cylinder 5.

[0060] The structure of the first control valve 3 according to an embodiment of the present invention will be described below:

[0061] According to an embodiment of the hydraulic system of the present invention, the first control valve 3 includes a valve body and a valve core.

[0062] The valve body is provided with a valve cavity, and the valve body is provided with a first valve port, a second valve port and a third valve port that are respectively connected to the valve cavity. The first valve port is connected to the oil tank, the second valve port is connected to the pressure supply device and the main oil circuit 20, and the third valve port is connected to the rodless cavity 51 of the oil cylinder 5.

[0063] The valve core is slidably disposed in the valve cavity. The valve core is provided with a first check valve 31 and a second check valve 30. The outlet of the first check valve 31 is connected to the outlet of the second check valve 30.

[0064] When the first control valve 3 is in the first working position, it has the following two states:

[0065] One state is that the first control valve 3 is in the fully operating position 11. At this time, the third valve port is connected to the second valve port through the first check valve 31 or the second check valve 30. Figure 1 As shown, the hydraulic oil in the rodless chamber 51 of the cylinder 5 can be returned to the main oil circuit 20 through the first check valve 31 or the second check valve 30 (connected to the second valve port via the first check valve 31).

[0066] Another state is that the first control valve 3 is in the half-operation position 12. At this time, the third valve port is connected to the second valve port through the first check valve 31 or the second check valve 30. Figure 1 The diagram shows a connection between the first check valve 31 and the second valve port, and also a connection between the first valve port and the second valve port.

[0067] Optionally, when the first control valve 3 is in the second working position 13, the third valve port is disconnected from the first valve port and the second valve port respectively, the pressure supply device stops supplying hydraulic oil to the rodless chamber 51 of the cylinder 5, and the hydraulic oil in the rodless chamber 51 of the cylinder 5 cannot flow into the oil tank or the main oil circuit 20.

[0068] When the first control valve 3 is in the third working position 14, the first valve port is connected to the inlet of the first check valve 31, the second valve port is connected to the outlet of the first check valve 31, and the third valve port is connected to the outlets of the first check valve 31 and the second check valve 30. The hydraulic oil supplied by the pressure supply device flows into the first control valve 3 through the second valve port, and after passing through the second check valve 30, flows into the rodless chamber 51 of the cylinder 5 through the third valve port of the first control valve 3.

[0069] According to an embodiment of the hydraulic system of the present invention, the inner wall of the valve cavity of the valve body is provided with a first annular groove 18, a second annular groove 4 and a third annular groove 19. The first annular groove 18 is connected to the first valve port, the second annular groove 4 is connected to the second valve port, and the third annular groove 19 is connected to the third valve port. The inner side of the valve core is provided with a first mounting cavity, a continuous channel 32 and a second mounting cavity connected in sequence. The side wall of the valve core is provided with a first through hole 25 connected to the first mounting cavity, a second through hole 24 connected to the continuous channel 32 and a third through hole 28 connected to the second mounting cavity. A first check valve 31 is provided in the first mounting cavity and a second check valve 30 is provided in the second mounting cavity. The first check valve 31 and the second check valve 30 are arranged facing each other.

[0070] In the above scheme, the first check valve 31 forms a one-way hydraulic channel between the first mounting cavity and the continuous channel 32, and the second check valve 30 forms a one-way hydraulic channel between the second mounting cavity and the continuous channel 32. The one-way conduction principle of the first check valve 31 and the second check valve 30 is described below:

[0071] The guide tip of the first check valve 31 abuts against the connection position between the first mounting cavity and the continuous channel 32 under the action of a spring. The first inlet pipe 34 of the first check valve 31 extends into the continuous channel 32. When high-pressure oil is introduced into the continuous channel 32, the hydraulic oil in the continuous channel 32 enters the first spring cavity 27 of the first check valve 31 through the first inlet pipe 34. At this time, since the diameter da of the guide tip of the first check valve 31 is smaller than the diameter Da of the first spring cavity 27, the hydraulic pressure on the guide tip of the first check valve 31 towards the first spring cavity 27 is less than the hydraulic pressure on the guide tip of the first check valve 31 towards the continuous channel 32. Therefore, the first check valve 31 remains in the state where the guide tip abuts against the connection position between the first mounting cavity and the continuous channel 32, and the hydraulic oil in the continuous channel 32 cannot flow into the first spring cavity 27. Inside the mounting cavity; when high-pressure oil is introduced into the first mounting cavity, the high-pressure oil acts on the outer annular groove of the guide front end of the first check valve 31. Since the area of ​​the side wall of the outer annular groove near the first spring cavity 27 is larger than the area of ​​the side wall near the continuous channel 32, the guide front end of the first check valve 31 bears the hydraulic resultant force toward the first spring cavity 27. If the hydraulic resultant force is greater than the spring force of the first check valve 31, it can push the guide front end of the first check valve 31 to move away from the continuous channel 32, so that the first mounting cavity and the continuous channel 32 are connected, and the hydraulic oil in the first mounting cavity can flow into the continuous channel 32.

[0072] The guide tip of the second check valve 30 abuts against the connection position between the second mounting cavity and the continuous channel 32 under the action of a spring. The second inlet pipe 33 of the second check valve 30 extends into the continuous channel 32. When high-pressure oil is introduced into the continuous channel 32, the hydraulic oil in the continuous channel 32 enters the second spring cavity 29 of the second check valve 30 through the second inlet pipe 33. At this time, since the diameter db of the guide tip of the second check valve 30 is smaller than the diameter Db of the second spring cavity 29 of the second check valve 30, the hydraulic pressure on the guide tip of the second check valve 30 towards the second spring cavity 29 is less than the hydraulic pressure on the guide tip of the second check valve 30 towards the continuous channel 32. Therefore, the second check valve 30 remains in the state where the guide tip abuts against the connection position between the second mounting cavity and the continuous channel 32, and the hydraulic oil in the continuous channel 32 cannot flow into the second spring cavity 29. Inside the mounting cavity; when high-pressure oil is introduced into the second mounting cavity, the high-pressure oil acts on the outer annular groove of the guide front end of the second check valve 30. Since the area of ​​the side wall of the outer annular groove near the second spring cavity 29 is larger than the area of ​​the side wall near the continuous channel 32, the guide front end of the second check valve 30 bears the hydraulic resultant force toward the second spring cavity 29. If the hydraulic resultant force is greater than the spring force of the second check valve 30, it can push the guide front end of the second check valve 30 to move away from the continuous channel 32, so that the second mounting cavity and the continuous channel 32 are connected, and the hydraulic oil in the second mounting cavity can flow into the continuous channel 32.

[0073] Based on the above scheme, it can be understood that since the first through hole 25 is connected to the first mounting cavity, the second through hole 24 is connected to the continuous channel 32, and the third through hole 28 is connected to the second mounting cavity, controlling the hydraulic oil flow state of the first through hole 25, the second through hole 24, and the third through hole 28 can control the opening and closing states of the first check valve 31 and the second check valve 30, thereby controlling the flow direction of the hydraulic oil. The hydraulic oil flow state of the first through hole 25, the second through hole 24, and the third through hole 28 can be controlled by moving the valve core within the valve cavity of the valve body.

[0074] Specifically, by applying the first signal pressure 21 to the left end of the valve core or applying the second signal pressure 22 to the right end of the valve core, the valve core can be moved along the valve cavity. For example... Figure 2 As shown, when the first through hole 25 is connected to the second annular groove 4 and the second through hole 24 is connected to the third annular groove 19, the first control valve 3 is in the full operating position 11. The hydraulic oil in the rodless chamber 51 can enter the first mounting chamber through the first through hole 25, and reach the continuous channel 32 through the first check valve 31, and then flow back to the main oil circuit 20 through the third through hole 28 and the third annular groove 19. When the first through hole 25 is connected to both the first annular groove 18 and the second annular groove 4, and the third through hole 28 is connected to the third annular groove 19, the first control valve 3 is in the half operating position 12. Part of the hydraulic oil in the rodless chamber 51 can enter the first annular groove 18 through the first through hole 25 and flow back to the oil tank. Another part of the hydraulic oil in the rodless chamber 51 can enter the first mounting chamber through the first through hole 25, and reach the continuous channel 32 through the first check valve 31, and then flow back to the main oil circuit 20 through the third through hole 28 and the third annular groove 19. Figure 3 As shown, when the first through hole 25 is displaced from the second annular groove 4, and the second through hole 24 is located between the second annular groove 4 and the third annular groove 19, and is simultaneously displaced from both the second annular groove 4 and the third annular groove 19, the first control valve 3 is placed in the second working position 13, and the position of the oil cylinder 5 is maintained; as Figure 4 As shown, when the second through hole 24 is connected to the second annular groove 4 and the third through hole 28 is connected to the third annular groove 19, the first control valve 3 is placed in the third working position 14. The hydraulic oil of the pressure supply device can enter the second mounting cavity through the third annular groove 19, and enter the continuous channel 32 through the second check valve 30, and then be supplied to the rodless cavity 51 of the oil cylinder 5 through the second through hole 24 and the second annular groove 4.

[0075] In some embodiments of the present invention, the hydraulic system further includes a second control valve 7. The first valve port of the second control valve 7 is connected to the rod chamber 52 of the cylinder 5, the second valve port of the second control valve 7 is connected to the rodless chamber 51 of the cylinder 5, the third valve port of the second control valve 7 is connected to the oil tank, and the fourth valve port of the second control valve 7 is connected to the oil supply device. The second control valve 7 has a fourth working position 15, a fifth working position 16, and a sixth working position 17.

[0076] When the second control valve 7 is placed in the fourth working position 15, the first valve port of the second control valve 7 is connected to the fourth valve port, and the second valve port of the second control valve 7 is connected to the first valve port in one direction. At this time, the hydraulic oil in the rodless chamber 51 and the hydraulic oil supplied by the pressure supply device can flow into the rod chamber 52, and the cylinder 5 retracts.

[0077] When the second control valve 7 is in the fifth working position 16, the first valve port of the second control valve 7 is connected to the third valve port, and the second valve port of the second control valve 7 is connected to the fourth valve port. At this time, the hydraulic oil supplied by the pressure supply device can be supplied to the rodless chamber 51 through the second control valve 7, and the hydraulic oil in the rod chamber 52 can also flow back to the oil tank through the second control valve 7, and the oil cylinder 5 extends.

[0078] When the second control valve 7 is in the sixth working position 17, the first valve port, the second valve port, the third valve port and the fourth valve port of the second control valve 7 are disconnected from each other. At this time, the hydraulic oil in the cylinder 5 cannot flow out through the second control valve 7, and the hydraulic oil supplied by the pressure supply device cannot be supplied to the cylinder 5 through the second control valve 7, and the position of the cylinder 5 is maintained.

[0079] Optionally, the pressure supply device includes a first oil pump 1 and a second oil pump 2. The oil outlet of the first oil pump 1 is connected to the second control valve 7 and the main oil circuit 20. The first oil pump 1 can supply oil to the oil cylinder 5 through the second control valve 7 and can also supply oil to the main oil circuit 20. The oil outlet of the second oil pump 2 is connected to the first control valve 3 and the main oil circuit 20. The second oil pump 2 can supply oil to the oil cylinder 5 through the first control valve 3 and can also supply oil to the main oil circuit 20.

[0080] Optionally, the hydraulic system also includes a third check valve, which is disposed in the connecting pipeline between the first oil pump 1 and the second control valve 7, forming a one-way passage from the first oil pump 1 to the second control valve 7.

[0081] Optionally, the hydraulic system also includes a load holding valve 9, which is connected to the first control valve 3, the second control valve 7 and the rodless chamber 51 of the cylinder 5.

[0082] This invention also provides a working machine, including the hydraulic system described above.

[0083] In embodiments of the present invention, the type of operating machinery is not limited; for example, the operating machinery can be an excavator, crane, loader, etc. In other words, it is acceptable as long as the operating machinery can use the hydraulic system of the present invention.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A hydraulic system, characterized in that, include: The oil cylinder (5), the first control valve (3), the pressure supply device, the main oil circuit (20) and the oil tank; The oil inlet of the pressure supply device is connected to the oil tank, and the oil outlet of the pressure supply device is connected to the first control valve (3); The first control valve (3) is connected to the rodless chamber (51) of the oil cylinder (5), the oil tank and the main oil circuit (20), and the first control valve (3) has a first working position; When the cylinder (5) retracts, the first control valve (3) is placed in the first working position, and the hydraulic oil in the rodless chamber (51) of the cylinder (5) flows back to the main oil circuit (20) through the first control valve (3); The first working position includes a full operating position (11) and a half operating position (12). When the first control valve (3) is in the full operating position (11), the rodless chamber (51) of the cylinder (5) is connected to the main oil circuit (20) through the first control valve (3), and the rodless chamber (51) of the cylinder (5) is disconnected from the oil tank. The hydraulic oil in the rodless chamber (51) of the cylinder (5) flows back to the main oil circuit (20) through the first control valve (3). When the first control valve (3) is in the half-operation position (12), the rodless chamber (51) of the cylinder (5) is connected to the main oil circuit (20) and the oil tank through the first control valve (3), and the hydraulic oil in the rodless chamber (51) of the cylinder (5) flows back to the main oil circuit (20) and the oil tank through the first control valve (3). The first control valve (3) includes: The valve body is provided with a valve cavity. The valve body is provided with a first valve port, a second valve port and a third valve port that are respectively connected to the valve cavity. The first valve port is connected to the oil tank, the second valve port is connected to the pressure supply device and the main oil circuit (20), and the third valve port is connected to the rodless cavity (51) of the oil cylinder (5). The valve core is provided with a first check valve (31) and a second check valve (30), and the outlet of the first check valve (31) is connected to the outlet of the second check valve (30). When the first control valve (3) is in the first working position: The third valve port is connected to the second valve port through the first check valve (31) or the second check valve (30); or, the third valve port is connected to the second valve port and the first valve port through the first check valve (31) or the second check valve (30).

2. The hydraulic system according to claim 1, characterized in that, The first control valve (3) also has a second working position (13) and a third working position (14). When the position of the cylinder (5) is maintained, the first control valve (3) is placed in the second working position (13), and the rodless chamber (51) of the cylinder (5) is simultaneously disconnected from the pressure supply device, the main oil circuit (20) and the oil tank; When the cylinder (5) extends outward, the first control valve (3) is placed in the third working position (14), the rodless chamber (51) of the cylinder (5) is connected to the pressure supply device and disconnected from the oil tank, and the pressure supply device supplies oil to the rodless chamber (51) of the cylinder (5) through the first control valve (3).

3. The hydraulic system according to claim 2, characterized in that, When the first control valve (3) is placed in the second working position (13), the third valve port is disconnected from the first valve port and the second valve port respectively; When the first control valve (3) is placed in the third working position (14), the first valve port is connected to the inlet of the first check valve (31), the second valve port is connected to the outlet of the first check valve (31), and the third valve port is connected to the outlets of the first check valve (31) and the second check valve (30).

4. The hydraulic system according to claim 1, characterized in that, The valve body has a first annular groove (18), a second annular groove (4) and a third annular groove (19) on the inner wall of the valve cavity. The first annular groove (18) is connected to the first valve port, the second annular groove (4) is connected to the second valve port, and the third annular groove (19) is connected to the third valve port. The valve core has a first mounting cavity, a continuous channel (32) and a second mounting cavity connected in sequence on its inner side. The side wall of the valve core has a first through hole (25) connected to the first mounting cavity, a second through hole (24) connected to the continuous channel (32) and a third through hole (28) connected to the second mounting cavity. The first check valve (31) is disposed in the first mounting cavity, and the second check valve (30) is disposed in the second mounting cavity. The first check valve (31) and the second check valve (30) are disposed facing each other.

5. The hydraulic system according to claim 1, characterized in that, Also includes: The second control valve (7) has a first valve port connected to the rod chamber (52) of the oil cylinder (5), a second valve port connected to the rodless chamber (51) of the oil cylinder (5), a third valve port connected to the oil tank, and a fourth valve port connected to the oil supply device. The second control valve (7) has a fourth working position (15), a fifth working position (16) and a sixth working position (17). When the second control valve (7) is placed in the fourth working position (15), the first valve port of the second control valve (7) is connected to the fourth valve port, and the second valve port of the second control valve (7) is connected to the first valve port in one direction. When the second control valve (7) is in the fifth working position (16), the first valve port of the second control valve (7) is connected to the third valve port, and the second valve port of the second control valve (7) is connected to the fourth valve port; When the second control valve (7) is placed in the sixth working position (17), the first valve port, the second valve port, the third valve port and the fourth valve port of the second control valve (7) are disconnected from each other.

6. The hydraulic system according to claim 5, characterized in that, The pressure supply device includes a first oil pump (1) and a second oil pump (2). The oil outlet of the first oil pump (1) is connected to the second control valve (7) and the main oil circuit (20). The oil outlet of the second oil pump (2) is connected to the first control valve (3) and the main oil circuit (20).

7. The hydraulic system according to claim 5 or 6, characterized in that, It also includes a load holding valve (9), which is connected to the first control valve (3), the second control valve (7) and the rodless chamber (51) of the cylinder (5).

8. A type of operating machinery, characterized in that, Includes the hydraulic system as described in any one of claims 1 to 7.

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