Hydraulic systems and construction machinery

Abstract

The present invention belongs to the field of engineering machinery, and discloses a hydraulic system and engineering machinery. The hydraulic system includes a main reversing valve, a first and a second pilot control valve, a pressure control device and a hydraulically controlled reversing valve. The pressure control device is connected between the main oil inlet oil circuit and the main oil return oil circuit to switch the control system to build pressure or release pressure; the hydraulically controlled reversing valve is used to pilot control the pressure control device, and the hydraulic control end of the hydraulically controlled reversing valve is connected to the high-pressure end in the first hydraulic control chamber and the second hydraulic control chamber. The present invention solves the problem of reversing pressure shock by hydraulic control, and uses the control chamber pressure of the main reversing valve to control the pilot valve (i.e., the hydraulically controlled reversing valve) of the pressure control device, thereby ensuring in hardware that the time for the main reversing valve to return to the center position is later than the unloading time of the pressure control device, and the time for the main reversing valve to switch to the center position is earlier than the pressure building time of the pressure control device, thereby ensuring that the system will not produce reversing shock, the system has high reliability and low cost, and improves the stability of the pumping system.

Description

Technical Field

[0001] The present invention belongs to the field of engineering machinery, and in particular, relates to a hydraulic system and engineering machinery. Background Art

[0002] Most actuators in construction machinery are driven by hydraulic systems. Pressure surge is a key indicator affecting the lifespan and reliability of hydraulic systems and components. For example, pumping equipment requires that pressure surges not exceed 50% of the system pressure. Therefore, necessary measures must be implemented in hydraulic systems to mitigate and control pressure surge indicators.

[0003] Switching pressure shock is the most common type of pressure shock in hydraulic systems. Existing technologies often use electronic control to control the switching timing of the main reversing valve and the timing of pressure buildup and pressure relief in the upstream oil circuit, thereby maintaining coordination and reducing switching pressure shock. However, this control method requires the response time of each solenoid valve to be consistent and stable over the long term, which makes control difficult and has limited versatility. Therefore, it is necessary to optimize the switching process specifically to improve and mitigate switching shock. Summary of the Invention

[0004] The main purpose of the present invention is to provide a hydraulic system and engineering machinery to significantly alleviate the switching pressure shock of the hydraulic system.

[0005] In order to achieve the above object, the present invention provides a hydraulic system, which includes:

[0006] A main reversing valve comprises a first hydraulic control chamber and a second hydraulic control chamber at both ends, one side of the main reversing valve being connected to a main oil inlet circuit and a main oil return circuit;

[0007] a first pilot control valve connected to the first hydraulic control chamber;

[0008] a second pilot control valve connected to the second hydraulic control chamber;

[0009] A pressure control device connected between the main oil inlet circuit and the main oil return circuit to switch the control system to build pressure or release pressure;

[0010] A hydraulically controlled reversing valve is used for pilot control of the pressure control device, wherein the hydraulically controlled end of the hydraulically controlled reversing valve is connected to the high-pressure ends of the first hydraulic control chamber and the second hydraulic control chamber.

[0011] In some embodiments, the hydraulic system comprises:

[0012] A shuttle valve, wherein the first comparative oil port of the shuttle valve is connected to the first hydraulic control chamber and the second comparative oil port is connected to the second hydraulic control chamber, and the inlet and outlet oil ports of the shuttle valve are connected to the hydraulic control end of the hydraulically controlled reversing valve.

[0013] In some embodiments, the hydraulically controlled reversing valve has a smaller diameter than the main reversing valve.

[0014] In some embodiments, one end of the hydraulically controlled reversing valve is the hydraulically controlled end, and the other end is a reverse control end that acts in the opposite direction to the hydraulically controlled end and has a controllable force.

[0015] In some embodiments, the reverse control end is provided with an adjustable return spring; or, the reverse control end is provided with an electromagnet with adjustable electromagnetic force.

[0016] In some embodiments, the oil outlet of the hydraulically controlled reversing valve is connected to the control port of the pressure control device, and the oil inlet of the hydraulically controlled reversing valve is provided with a hydraulic damping member.

[0017] In some embodiments, the main reversing valve includes a main oil inlet and a main oil return port on one side and a working oil port on the other side, the main oil inlet is connected to the main oil inlet oil circuit, and the main oil return port is connected to the main oil return oil circuit;

[0018] Wherein, in the middle position of the main reversing valve, the main oil inlet and the main oil return port are cut off from communication, or a throttling element is provided between the main oil inlet and the main oil return port.

[0019] In some embodiments, the pressure control device is a pilot relief valve.

[0020] In some embodiments, the first pilot control valve and the second pilot control valve are both two-position three-way solenoid reversing valves, or the first pilot control valve and the second pilot control valve are integrated into a three-position four-way solenoid valve.

[0021] In some embodiments, the hydraulic system comprises:

[0022] The pumping cylinder group, the main reversing valve is used to drive and switch control the pumping cylinder group.

[0023] In addition, the present invention also provides an engineering machine, which includes the hydraulic system according to the present invention.

[0024] In some embodiments, the engineering machine is a pumping equipment.

[0025] The present invention solves the problem of switching pressure shock through hydraulic control. It uses a hydraulically controlled reversing valve to pilot-control the pressure control device to control the system pressure building or pressure relief. At the same time, the hydraulic control end of the hydraulically controlled reversing valve is connected to the high-pressure end of the control chamber at both ends of the main reversing valve. Therefore, the control chamber pressure of the main reversing valve is used to control the pressure control device. This ensures in hardware that the time for the main reversing valve to return to the center position is later than the unloading of the pressure control device, and the time for the main reversing valve to switch to the position is earlier than the pressure building of the pressure control device, ensuring that the system will not produce switching shock.

[0026] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are used to provide an understanding of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0028] Figure 1 A hydraulic principle diagram of a hydraulic system according to a specific embodiment of the present invention;

[0029] Figure 2 A hydraulic principle diagram of a hydraulic system according to another specific embodiment of the present invention;

[0030] Figures 3 to 6 The diagram shows several other forms of mid-position structures of the main reversing valve.

[0031] Description of Reference Numerals

[0032] 1 Main reversing valve 3 Pressure control device

[0033] 4 Pumping cylinder group 5 Fuel tank

[0034] 6 Hydraulic control reversing valve 61 adjustable return spring

[0035] 7 Shuttle valve 8 Hydraulic damping element

[0036] 2-1 First pilot control valve 2-2 Second pilot control valve

[0037] 4-1 First pumping cylinder 4-2 Second pumping cylinder

[0038] L0 main oil return line L1 main oil inlet line

[0039] P Main oil inlet T Main oil return

[0040] A1 first working oil port A2 second working oil port DETAILED DESCRIPTION

[0041] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0042] The hydraulic system and the construction machine according to the present invention will be described below with reference to the accompanying drawings.

[0043] See also Figure 1 or Figure 2 In a specific embodiment of the present invention, a hydraulic system is disclosed, comprising:

[0044] The main reversing valve 1 includes a first hydraulic control chamber and a second hydraulic control chamber at both ends. One side of the main reversing valve 1 is connected to the main oil inlet circuit L1 and the main oil return circuit L0;

[0045] The first pilot control valve 2-1 is connected to the first hydraulic control chamber;

[0046] The second pilot control valve 2-2 is connected to the second hydraulic control chamber;

[0047] The pressure control device 3 is connected between the main oil inlet line L1 and the main oil return line L0 to switch the control system to build pressure or release pressure; and

[0048] The hydraulically controlled reversing valve 6 is used for pilot-controlling the pressure control device 3 , and the hydraulically controlled end of the hydraulically controlled reversing valve 6 is connected to the high-pressure end in the first hydraulically controlled chamber and the high-pressure end in the second hydraulically controlled chamber.

[0049] The present invention aims to solve the problem of switching pressure shock through hydraulic control, and uses the control chamber pressure of the main reversing valve 1 to control the pilot valve (i.e., the hydraulically controlled reversing valve 6) of the pressure control device 3, thereby ensuring in hardware that the time when the main reversing valve 1 returns to the center position is later than the unloading of the pressure control device, and the time when the main reversing valve switches to the right position is earlier than the pressure building of the pressure control device, ensuring that the system will not produce switching shock.

[0050] To connect the hydraulically controlled end of hydraulically controlled reversing valve 6 to the high-pressure ends of the first and second hydraulic control chambers, the control oil in the first and second hydraulic control chambers can be pressure-compared, and the higher pressure oil can be delivered to the hydraulically controlled end of hydraulically controlled reversing valve 6. In this embodiment, a shuttle valve 7 is provided in the hydraulic system. The first comparison oil port of shuttle valve 7 is connected to the first hydraulic control chamber, and the second comparison oil port is connected to the second hydraulic control chamber. The inlet and outlet oil ports of shuttle valve 7 are connected to the hydraulically controlled end of hydraulically controlled reversing valve 6.

[0051] When the hydraulic system is working, the main reversing valve 1 drives the control actuators, such as various oil cylinders, etc. Figure 1In this embodiment, the pumping cylinder group 4 is used. When the pumping cylinder group 4 is activated and the first pumping cylinder 4-1 needs to extend, the first pilot control valve 2-1 is energized, the second pilot control valve 2-2 is de-energized, and the main reversing valve 1 is in the left position. At this point, the main oil inlet line L1 connects to the first working oil port A1 through the main inlet port of the main reversing valve 1. Pressurized oil then flows to the rodless chamber of the first pumping cylinder 4-1. The rodless chamber of the second pumping cylinder 4-2 returns oil, and the oil returns to the oil tank 5 through the connected second working oil port A2 and the main return port T via the main return line L0. At this time, it is obvious that the first hydraulic control chamber at the left end of the main reversing valve 1 is the high-pressure end, and the second hydraulic control chamber is the low-pressure end. After passing through the shuttle valve 7, the pressure oil in the first hydraulic control chamber flows to the hydraulic control end of the hydraulic control reversing valve 6, so that the hydraulic control reversing valve 6 is in the left position. The pressure oil in the main oil inlet oil circuit L1 flows as the pilot oil through the hydraulic control reversing valve 6 to the control port of the pressure control device 3, thereby controlling the system to build pressure or maintain the pressure-built state.

[0052] In this embodiment, both the first pilot control valve 2-1 and the second pilot control valve 2-2 are solenoid valves, but this is not limiting. When the main reversing valve 1 is switched, the first pilot control valve 2-1 loses power first, causing the pressure in the first hydraulic control chamber on the left side of the main reversing valve 1 to begin to drop. Simultaneously, the control pressure of the hydraulic control reversing valve 6 also decreases. When the pressure drops to the set value, the hydraulic control reversing valve 6 returns to the right position, the control port of the pressure control device 3 connects to the oil tank 5, and the system is unloaded. When the pressure in the first hydraulic control chamber of the main reversing valve 1 drops to a certain value (dependent on the force of the return springs at both ends of the main reversing valve 1), the main reversing valve 1 begins to reset.

[0053] In this embodiment, the hydraulically controlled reversing valve 6 has a smaller diameter than the main reversing valve 1. As a result, due to its smaller size, its reset time is much shorter than that of the main reversing valve 1. Therefore, before the main reversing valve 1 returns to its neutral position, the hydraulically controlled reversing valve 6 has already shifted to the right position, effectively resetting the valve earlier. This allows the system to unload earlier and prevents main valve shift shock. Simultaneously, the stiffness of the return spring of the hydraulically controlled reversing valve 6 can be increased, ensuring that its operating pressure is higher than that of the main reversing valve 1, ensuring that the hydraulically controlled reversing valve 6 is unloaded first.

[0054] When, after a certain delay, the second pumping cylinder 4-2 needs to be extended, the second pilot control valve 2-2 is energized and the first pilot control valve 2-1 is de-energized. The pilot pressure oil at port P2 flows to the second hydraulic control chamber on the right side of the main reversing valve 1, allowing the main reversing valve 1 to switch to the right position. Simultaneously, the hydraulic pressure at the hydraulic control end of the hydraulic control reversing valve 6 also rises. When it reaches the set value, the hydraulic control reversing valve 6 switches to the left position under the action of pressure. The control pressure enters the control port of the pressure control device 3 through the hydraulic control reversing valve 6, and the pressure control device 3 begins to build pressure, allowing the system to build pressure. Thus, when the pressure in the right-end control chamber of the main reversing valve 1 begins to rise to a certain value, the main reversing valve 1 moves to the right position, and the actuator moves in the opposite direction.

[0055] During the movement of the spool of main reversing valve 1, the pressure in its control chamber remains relatively low. Only when the spool reaches its final position does the pressure in the control chamber rise rapidly. Therefore, in this embodiment, the stiffness of the return spring of hydraulically piloted reversing valve 6 is carefully controlled so that its operating pressure is higher than that of main reversing valve 1. This ensures that main reversing valve 1 reaches its final position before hydraulically piloted reversing valve 6.

[0056] In this embodiment, the actuator is a pumping cylinder group 4, in which the first pumping cylinder 4-1 and the second pumping cylinder 4-2 extend alternately. Therefore, the electronic control system automatically and alternately delays the operation of the first pilot control valve 2-1 and the second pilot control valve 2-2 to achieve continuous pumping. Of course, the actuator of the hydraulic system of the present invention is not limited to a pumping cylinder group; other mechanisms, such as a rotary motor, may also be employed, and further description thereof will not be given here.

[0057] In summary, the present invention solves the problem of switching pressure shock through hydraulic control. In terms of hardware, it ensures that the time when the main reversing valve 1 returns to the center position is later than the unloading of the pressure control device, and the time when the main reversing valve switches to the position is earlier than the pressure building of the pressure control device, ensuring that the system will not produce switching shock.

[0058] Comparatively, the prior art requires precise matching of the power on / off times of the pilot valve of the main reversing valve 1 with the power on / off times of the pilot valve of the pressure control device 3. When the matching is unreasonable, for example, if the power off time of the pilot valve of the pressure control device 3 is too late, the pressure control device 3 has not yet been unloaded, and the main hydraulic valve 1 has returned to the neutral position, the system will experience a reversing pressure shock. Similarly, if the pilot valve of the pressure control device 3 is energized too early, the main reversing valve 1 has not yet switched to the other end when the pressure control device 3 builds pressure, and the oil ports of the main reversing valve 1 are still closed or have very small openings, the system will also experience a shock. Moreover, it is difficult to maintain the response time of each valve component consistent. During use, the response time will also change due to the influence of temperature, pressure, wear, etc. The indicators set at the factory are difficult to adapt to all situations, which can easily cause the system to experience shocks due to unreasonable time matching.

[0059] Furthermore, in the prior art, the response time of each valve varies not only due to component consistency and changes in operating parameters during use, but also requires long delays between the energization and de-energization of each electromagnet to ensure the logical relationship between valve operation in various situations, thus affecting system efficiency. In contrast, the present invention establishes a fixed logical relationship between the operation sequence of the main reversing valve 1 and the hydraulically controlled reversing valve 6, thus providing a greater ability to adapt to various operating conditions.

[0060] See also Figure 2In the embodiment shown, one end of the hydraulic control reversing valve 6 is the hydraulic control end, and the other end is the reverse control end which has a controllable force and acts in the opposite direction to the hydraulic control end. The reversing timing of the hydraulic control reversing valve 6 is determined by the set reset force of the reverse control end. Figure 2 In the case where the reverse control end shown is provided with an adjustable return spring 61, the spring force of the adjustable return spring 61 determines the reversing timing. Figure 2 The spring force of the adjustable return spring 61 of the hydraulically controlled reversing valve 6 is set to an adjustable state to adapt to different reversing pressures. Of course, those skilled in the art will understand that the reverse control end may also be provided with an electromagnet with adjustable electromagnetic force, i.e. Figure 2 The spring force may also be replaced by electromagnetic force or adjustable electromagnetic force, all within the scope of protection of the present invention.

[0061] Furthermore, to control the pressure-building time of the pressure control device 3, a hydraulic damping element 8 can be provided at the oil inlet of the hydraulically controlled reversing valve 6, while the oil outlet of the hydraulically controlled reversing valve 6 is connected to the control port of the pressure control device 3. With the provision of the hydraulic damping element 8, the pressure-building time of the pressure control device 3 can be extended and adjusted, ensuring that the pressure control device 3 can only build pressure when the main reversing valve 1 is in full (or nearly full) reversal position.

[0062] In addition, the main reversing valve 1 includes a main oil inlet P and a main oil return port T on one side and a first working oil port A1 and a second working oil port A2 on the other side. The main oil inlet P is connected to the main oil inlet oil circuit L1, and the main oil return port T is connected to the main oil return oil circuit L0; wherein, in the middle position of the main reversing valve 1, the main oil inlet P and the main oil return port T are cut off from communication, or a throttling element is provided between the main oil inlet P and the main oil return port T.

[0063] In other words, in Figure 1 、 Figure 2 In the middle position of the main reversing valve 1, the four oil ports are disconnected, that is, the main oil inlet P, the main oil return port T, the first working oil port A1, and the second working oil port A2 are all disconnected. However, other middle position functions are also possible. Figures 3 to 6 It should be noted that any situation where the system pressure is not too high when in the neutral position, including the main oil inlet P and the main oil return port T being disconnected or not fully connected, is within the scope of protection of the present invention.

[0064] It should be noted that in Figure 1 、 Figure 2In this embodiment, the pressure control device 3 can be a pilot relief valve or other relief valve assembly. Both the first pilot control valve 2-1 and the second pilot control valve 2-2 are two-position, three-way solenoid directional valves. However, those skilled in the art will appreciate that the first pilot control valve 2-1 and the second pilot control valve 2-2 can also be integrated into a three-position, four-way solenoid valve. Similarly, the main directional valve 1 can be a single or multiple main valve.

[0065] The pilot oil sources for the main reversing valve 1 and the pressure control device 3 are derived from ports P1 and P2, respectively, as shown in the figure, but can also be derived from the same source. The actuator in this embodiment is a pumping cylinder group 4, but this is not limited to this. The hydraulic damping element 8 provided upstream of the hydraulically controlled reversing valve 6 can be variable or fixed, and can be electrically or manually controlled. Furthermore, the shuttle valve 7 is a selector valve that selects high pressure flow. Its specific structure and illustrated shape are not limited to those shown in the figure; for example, a spool valve type can also be depicted.

[0066] On the basis of the above hydraulic system, the present invention also protects engineering machinery having the hydraulic system. Obviously, the engineering machinery is not limited to the above pumping equipment, which has the advantage of small switching pressure shock.

[0067] In summary, the present invention adopts a hydraulically controlled reversing valve to control the pressure control device, adopts a shuttle valve to select the medium or high pressure at both ends of the main reversing valve to control the reversing of the hydraulically controlled reversing valve, and also adds damping at the oil inlet end of the hydraulically controlled reversing valve to extend the pressure building time of the pressure control device. In addition, an adjustable spring force is used to adapt to different control pressures, and finally the problem of reversing pressure shock is solved by hydraulic control, and the system has high reliability and low cost.

[0068] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0069] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0070] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0071] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A hydraulic system, characterized in that: The hydraulic system comprises: A main reversing valve (1) comprises a first hydraulic control chamber and a second hydraulic control chamber located at both ends, and one side of the main reversing valve (1) is connected to a main oil inlet circuit (L1) and a main oil return circuit (L0); a first pilot control valve (2-1), connected to the first hydraulic control chamber; a second pilot control valve (2-2), connected to the second hydraulic control chamber; A pressure control device (3) connected between the main oil inlet circuit (L1) and the main oil return circuit (L0) to switch the control system to build up pressure or release pressure; A hydraulically controlled reversing valve (6) is used for pilot-controlling the pressure control device (3), wherein the hydraulically controlled end of the hydraulically controlled reversing valve (6) is connected to the high-pressure ends of the first hydraulically controlled chamber and the second hydraulically controlled chamber.

2. The hydraulic system according to claim 1, characterized in that The hydraulic system comprises: A shuttle valve (7), wherein a first comparative oil port of the shuttle valve (7) is connected to the first hydraulic control chamber and a second comparative oil port is connected to the second hydraulic control chamber, and an inlet and an outlet oil port of the shuttle valve (7) are connected to the hydraulic control end of the hydraulic control reversing valve (6).

3. The hydraulic system according to claim 1, characterized in that The diameter of the hydraulically controlled reversing valve (6) is smaller than that of the main reversing valve (1).

4. The hydraulic system according to claim 1, characterized in that One end of the hydraulically controlled reversing valve (6) is the hydraulically controlled end, and the other end is a reverse control end that acts in the reverse direction to the hydraulically controlled end and whose acting force is controllable.

5. The hydraulic system according to claim 4, characterized in that The reverse control end is provided with an adjustable return spring (61); or, the reverse control end is provided with an electromagnet with adjustable electromagnetic force.

6. The hydraulic system according to any one of claims 1 to 5, characterized in that: The oil outlet end of the hydraulically controlled reversing valve (6) is connected to the control port of the pressure control device (3), and the oil inlet end of the hydraulically controlled reversing valve (6) is provided with a hydraulic damping component (8).

7. The hydraulic system according to claim 1, characterized in that The main reversing valve (1) comprises a main oil inlet (P) and a main oil return port (T) on one side and working oil ports (A1, A2) on the other side, wherein the main oil inlet (P) is connected to the main oil inlet oil circuit (L1), and the main oil return port (T) is connected to the main oil return oil circuit (L0); Wherein, in the middle position of the main reversing valve (1), the main oil inlet (P) and the main oil return port (T) are cut off from communication, or a throttling element is provided between the main oil inlet (P) and the main oil return port (T).

8. The hydraulic system according to claim 1, wherein: The pressure control device (3) is a pilot relief valve.

9. The hydraulic system according to claim 1, wherein: The first pilot control valve (2-1) and the second pilot control valve (2-2) are both two-position three-way solenoid reversing valves, or the first pilot control valve (2-1) and the second pilot control valve (2-2) are integrated into a three-position four-way solenoid valve.

10. The hydraulic system according to claim 1, wherein: The hydraulic system comprises: A pumping cylinder group (4), wherein the main reversing valve (1) is used for driving and switching the pumping cylinder group (4).

11. An engineering machine, characterized in that: The construction machine includes the hydraulic system according to any one of claims 1 to 10.

12. The construction machine according to claim 11, characterized in that: The engineering machinery is pumping equipment.

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