Blade floatable lift hydraulic system for bulldozers and excavators

Abstract

This invention discloses a bulldozer hydraulic system with a floating and lifting bulldozer blade, comprising: an oil tank; a working pump; a bulldozer blade cylinder; and a switching device, including a control component and a directional valve. The control component includes a handle assembly, a first valve, a second valve, a third valve, a first port, a second port, and a third port and a fourth port connected to the hydraulic control end of the directional valve. In a first working state, the first valve is in the first valve second position, and the second valve is in the second valve first position. In a second working state, the first valve is in the first valve first position, the second valve is in the second valve second position, and the third valve is in the third valve second position. In a third working state, the first valve is in the first valve first position, the second valve is in the second valve second position, and the third valve is in the third valve first position, and the oil output from the first port of the third valve causes the valve core of the first valve to compress a first compression spring so that the third valve is held in the third valve first position.

Description

Technical Field

[0001] This invention relates to the field of engineering machinery technology, and in particular to a bulldozing hydraulic system with a floating and lifting bulldozer blade and an excavator. Background Technology

[0002] One design trend in hydraulic systems for construction machinery is towards increasing functionality. For example, some excavators are equipped with bulldozer blades to enable rapid leveling operations. The bulldozer blade's rise and fall are controlled by the extension and retraction of its hydraulic cylinders. To improve efficiency during ditch backfilling and site leveling, a floating function is added, allowing the bulldozer blade to automatically rise and fall to adapt to uneven terrain. Summary of the Invention

[0003] The purpose of this invention is to provide a bulldozing hydraulic system with a floating and lifting bulldozer blade, which can realize effective manual control of the lifting and lowering of the bulldozer blade during operation and maintain the stable and reliable floating and lifting state of the bulldozer blade.

[0004] This invention discloses a bulldozing hydraulic system with a floating and lifting bulldozer blade, having a first working state, a second working state, and a third working state, including:

[0005] tank;

[0006] Working pump;

[0007] A bulldozer blade cylinder is used to connect with a bulldozer blade. The bulldozer blade cylinder raises the bulldozer blade in one of the first working states and the second working states, and lowers the bulldozer blade in the other working state. The bulldozer blade cylinder causes the bulldozer blade to float up and down in the third working state.

[0008] A switching device includes a control component and a reversing valve. The reversing valve is connected between the working pump, the oil tank, and the bulldozer cylinder, and is used to control the flow direction of the oil between the working pump, the oil tank, and the bulldozer cylinder. In a first operating state, the reversing valve is in a first valve position; in a second operating state, the reversing valve is in a second valve position; and in a third operating state, the reversing valve is in a third valve position. The control component includes a handle assembly, a first valve, a second valve, a third valve, a first port connected to the working pump, a second port connected to the oil tank, and a third port and a fourth port connected to the hydraulic control end of the reversing valve. The control component is used to adjust the pressure of the oil output from the third port and the fourth port to make the reversing valve in the first valve position. Switching between the second valve position and the third valve position; the first valve includes a first hydraulic control end, a first hydraulic control port disposed on the first hydraulic control end, a first spring, a first valve first port, a first valve second port, and a first valve third port; the second valve includes a second spring, a second valve first port, a second valve second port, and a second valve third port; the third valve includes a third valve first port, a third valve second port, and a third valve third port; the third valve first port is connected to the first hydraulic control port, the third valve second port is connected to the second valve first port, and the third valve third port is connected to the second port; the first valve first port is connected to the third port, the second valve first port is connected to the fourth port, and the first valve second port is connected to the... The second valve has a second oil port connected to the second port, and the first valve has a third oil port connected to the third oil port of the second valve and the first port; the handle assembly includes a frame, a connector hinged to the frame in the middle, a first compression spring disposed between the first end of the connector and the first valve, and a second compression spring disposed between the second end of the connector and the second valve, the first compression spring and the second compression spring being located on the same side of the connector; the first valve has a first valve position where the first valve's first oil port and the first valve's second oil port communicate, and a first valve position where the first valve's first oil port and the first valve's third oil port communicate, the elastic force of the first spring causing the valve core of the first valve to tend towards the first valve's... The valve moves in the direction of switching to the first valve's first position; the second valve has a second valve's first position where the second valve's first oil port and second valve's second oil port are connected, and a second valve's second position where the second valve's first oil port and second valve's third oil port are connected; the elastic force of the second spring causes the valve core of the second valve to tend to move in the direction of switching the second valve to the second valve's first position; the third valve has a third valve's first position where the third valve's first oil port and third valve's second oil port are connected, and the valve core of the third valve is drivenly connected to the valve core of the second valve; when the second valve is in the second valve's first position, the third valve is in the third valve's second position;When the second valve switches from the first valve position to the second valve position, the valve core of the second valve moves along a first direction; when the third valve switches from the second valve position to the first valve position, the valve core of the third valve moves along a second direction; when the valve core of the second valve moves along the first direction, the valve core of the third valve is driven by the valve core of the second valve to move along the second direction; after the second valve switches from the first valve position to the second valve position, the valve core of the second valve can continue to move along the first direction to increase the flow area between the first port and the third port of the second valve, and after the valve core of the second valve continues to move a first distance along the first direction, the third valve switches from the second valve position to the first valve position; the handle assembly is configured such that: pressing down the first end of the connector can compress the first compression spring and push the first valve to switch via the first compression spring. When switching to the second valve position of the first valve, the second compression spring can be compressed by pressing down the second end of the connecting member, and the second valve can be switched to the second valve position by the second compression spring. In the first working state, the first valve is in the second valve position and the second valve is in the first valve position. In the second working state, the first valve is in the first valve position, the second valve is in the second valve position, and the third valve is in the second valve position. In the third working state, the first valve is in the first valve position, the second valve is in the second valve position, and the third valve is in the first valve position, and the oil output from the first port of the third valve causes the valve core of the first valve to compress the first compression spring, and the first compression spring presses the connecting member and the connecting member presses the second compression spring, so that the third valve is held in the first valve position.

[0009] In some embodiments, a third spring is also included, the third spring being configured such that after the second valve switches from the first valve position to the second valve position, the valve core of the second valve moves a first distance in the first direction and its continued movement in the first direction is subject to the elastic resistance of the third spring.

[0010] In some embodiments, the third valve further includes a fourth spring, the elastic force of which causes the valve core of the third valve to move in a direction that causes the third valve to switch to the second valve position.

[0011] In some embodiments, the first port of the first valve is connected to the first hydraulic control terminal, and the pressure of the oil output from the first port of the first valve to the first hydraulic control terminal causes the valve core of the first valve to tend to move in the direction that causes the first valve to switch to the first valve position.

[0012] In some embodiments, the second valve includes a second hydraulic control terminal, and a first oil port of the second valve is connected to the second hydraulic control terminal. The pressure of the oil output from the first oil port of the second valve to the second hydraulic control terminal causes the valve core of the second valve to tend to move in a direction opposite to the first direction.

[0013] In some embodiments, a pressure reducing valve is further included, connected between the working pump and the first port, the outlet of the pressure reducing valve being connected to the first port.

[0014] In some embodiments, the hydraulic control terminals of the directional valve include a third hydraulic control terminal and a fourth hydraulic control terminal located on opposite sides. The third port is connected to the third hydraulic control terminal, and the fourth port is connected to the fourth hydraulic control terminal. When the pressure of the oil output from the third port is greater than a first threshold, the oil output from the third port pushes the valve core of the directional valve to move to a position where the directional valve switches to a first valve position. When the pressure of the oil output from the fourth port is greater than a second threshold and less than a third threshold, the oil output from the fourth port pushes the valve core of the directional valve to move to a position where the directional valve switches to a second valve position. When the pressure of the oil output from the fourth port is greater than a third threshold, the oil output from the fourth port pushes the valve core of the directional valve to move to a position where the directional valve switches to a third valve position.

[0015] In some embodiments, the bulldozer blade cylinder includes a first oil chamber and a second oil chamber. In a first operating state, the reversing valve controls the oil output from the working pump to be input into the first oil chamber and controls the oil output from the second oil chamber to be output into the oil tank. In a second operating state, the reversing valve controls the oil output from the working pump to be input into the second oil chamber and controls the oil output from the first oil chamber to be output into the oil tank. In a third operating state, the reversing valve controls the first oil chamber and the second oil chamber to be simultaneously connected to the oil tank.

[0016] A second aspect of the present invention discloses an excavator, including a bulldozer blade and a bulldozer hydraulic system for floating and lifting the bulldozer blade as described above.

[0017] Based on the floating and lifting bulldozer hydraulic system provided by this invention, pressing down the end of the connecting member allows the bulldozer blade cylinder to enter different working states, thereby enabling the bulldozer blade to rise, fall, or float. Furthermore, when one end of the connecting member is pressed down, the other end of the connecting member will tilt upwards, preventing accidental operation of the first valve, second valve, and second valve positions simultaneously, thus contributing to system safety. Simultaneously, after entering the third working state, the third valve in the switching device can output hydraulic fluid to provide hydraulic feedback to the valve core of the first valve, maintaining the first valve in its first position, the second valve in its second position, and the third valve in its third position. This allows the bulldozer blade to effectively maintain a floating and lifting working state for extended periods.

[0018] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0020] Figure 1 This is a schematic diagram of the structural principle of the floating and lifting bulldozing hydraulic system of the bulldozer blade according to an embodiment of the present invention;

[0021] Figure 2 for Figure 1 A magnified view of a portion of the image. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0024] In the description of this invention, it should be understood that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0025] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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 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 this invention based on the specific circumstances.

[0026] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0027] like Figure 1 and Figure 2 The bulldozing hydraulic system shown has a first working state, a second working state, and a third working state. The bulldozing hydraulic system includes an oil tank 17, a working pump 11, a bulldozing cylinder 13, and a switching device.

[0028] The bulldozer blade is typically a working component of a bulldozer, and its structural shape is generally straight or U-shaped. Some excavators and other construction machinery also have bulldozer blades installed to expand their functionality. The bulldozer blade cylinder 13 is connected to the bulldozer blade. In one of its first and second working states, the cylinder raises the bulldozer blade; in the other state, it lowers it. In a third working state, the cylinder allows the bulldozer blade to float and rise / fall. For example, in… Figure 1 In the embodiment shown, the bulldozer blade cylinder includes a rod chamber A and a rodless chamber B. In the first working state, oil is introduced into the rod chamber A, the piston rod retracts, and the bulldozer blade descends. In the second working state, oil is introduced into the rodless chamber B, the piston rod extends, and the bulldozer blade rises. In the third working state, both the rod chamber A and the rodless chamber B are connected to the oil tank 17, the piston rod floats and extends, and the bulldozer blade floats and rises. When working, the bulldozer blade can passively rise and fall according to the unevenness of the site surface, better adapting to the shape of the site surface.

[0029] The switching device includes a control component 8 and a reversing valve 23. The reversing valve 23 is connected between the working pump 11, the oil tank 17, and the bulldozer blade cylinder 13. The reversing valve 23 is used to control the direction of oil flow between the working pump 11, the oil tank 17, and the bulldozer blade cylinder 13. In the first working state, the reversing valve 23 is in the first valve position; in the second working state, the reversing valve 23 is in the second valve position; and in the third working state, the reversing valve 23 is in the third valve position. By switching the valve position, the reversing valve 23 adjusts the direction of oil flow, for example, causing the oil from the working pump to flow into different chambers of the bulldozer blade cylinder to change the bulldozer blade's rising or falling state, or causing different chambers of the bulldozer blade to be connected to the oil tank to enter a floating lifting state.

[0030] Control assembly 8 includes a handle assembly, a first valve 81, a second valve 82, a third valve 83, a first port connected to the working pump 11, a second port connected to the oil tank 17, and a third and fourth port connected to the hydraulic control end of the directional valve 23. Figure 2 In the illustrated embodiment, the first port, second port, third port, and fourth port are respectively the first hydraulic port P, the second hydraulic port T, the third hydraulic port a, and the fourth hydraulic port b. The control component 8 is used to adjust the pressure of the oil output from the third port and the fourth port to switch the directional valve 23 between the first valve position, the second valve position, and the third valve position. That is, the directional valve 23 is a hydraulically controlled directional valve, and the valve position switching of the directional valve 23 is controlled by the control component 8. The control component 8 performs different controls on the hydraulically controlled end of the directional valve 23 by outputting different oil pressures from the third port and the fourth port, thereby switching the valve position of the directional valve. In the embodiment shown, adjusting the pressure of the oil output from the third port and the fourth port includes making the third port output oil or not output oil, making the fourth port output oil or not output oil, making one of the third port and the fourth port output oil, and changing the pressure of the oil output from the third port and / or the fourth port, etc.

[0031] like Figure 1 and Figure 2 As shown, the first valve 81 includes a first hydraulic control end, a first hydraulic control port disposed on the first hydraulic control end, a first spring 811, a first valve first port, a first valve second port, and a first valve third port; the second valve 82 includes a second spring 821, a second valve first port, a second valve second port, and a second valve third port; the third valve 83 includes a third valve first port, a third valve second port, and a third valve third port; the third valve first port is connected to the first hydraulic control port, the third valve second port is connected to the second valve first port, and the third valve third port is connected to the second port; the first valve first port is connected to the third port, the second valve first port is connected to the fourth port, the first valve second port and the second valve second port are connected to the second port, and the first valve third port and the second valve third port are connected to the first port.

[0032] The handle assembly includes a frame, a connector 84 hinged to the frame at its center, a first compression spring 841 located between a first end of the connector 84 and a first valve 81, and a second compression spring 842 located between a second end of the connector 84 and a second valve 82. The first compression spring 841 and the second compression spring 842 are located on the same side of the connector 84. In the embodiment shown, the connector 84 is a connecting rod, and the middle part of the connecting rod is indirectly connected to the frame via a rod-shaped connecting member to achieve hinge. The first end and the second end of the connector are located on opposite sides of the hinge point between the connector and the frame, so that in the embodiment shown, when one of the first end and the second end of the connector rises, the other falls. That is, when one of the first end and the second end of the connector 84 compresses its corresponding compression spring, the other will not compress its corresponding compression spring.

[0033] The first valve 81 has a first valve position where the first valve's first port and second port are connected, and a second valve position where the first valve's first port and third port are connected. The elastic force of the first spring 811 causes the valve core of the first valve 81 to tend to move in the direction that switches the first valve 81 to the first valve position. The second valve 82 has a second valve position where the second valve's first port and second port are connected, and a second valve position where the second valve's first port and third port are connected. The elastic force of the second spring 821 causes the valve core of the second valve 82 to tend to move in the direction that switches the second valve 82 to the second valve position. The third valve 83 has a first valve position where the first and second oil ports of the third valve are connected, and a second valve position where the first and third oil ports of the third valve are connected. The valve core of the third valve 83 is drivenly connected to the valve core of the second valve 82, meaning that the movement of the valve core of the second valve 82 can drive the movement of the valve core of the third valve 83. The valve cores of the second valve 82 and the third valve 83 can be directly or indirectly connected. In the embodiment shown in the figure, the valve cores of the second valve 82 and the third valve 83 are rigidly connected through a rod-shaped connecting part to achieve a driving connection. When the second valve is in the first valve position, the third valve is in the second valve position; when the second valve 82 switches from the first valve position to the second valve position, the valve core of the second valve 82 moves along a first direction. When the third valve 83 switches from the second valve position to the first valve position, the valve core of the third valve 83 moves along the second direction; when the valve core of the second valve 82 moves along the first direction, the valve core of the third valve 83 is driven by the valve core of the second valve 82 to move along the second direction. In the embodiment shown in the figure, the first direction and the second direction are the same. After the second valve 82 switches from the first valve position to the second valve position (in this embodiment, this refers to the instant after the second valve 82 switches from the first valve position to the second valve position, that is, the instant after the first oil port of the second valve and the third oil port of the second valve are connected), the valve core of the second valve 82 can continue to move along the first direction to increase the flow area between the first oil port of the second valve and the third oil port of the second valve. After the valve core of the second valve 82 continues to move a first distance along the first direction, the third valve 83 switches from the second valve position to the first valve position. That is, the first oil port of the second valve and the third oil port of the second valve 82 can be connected and disconnected as the valve core of the second valve 82 moves. After the connection is achieved, the flow area can be increased as the valve core of the second valve 82 moves, thereby further reducing the pressure difference between the first oil port of the second valve and the third oil port of the second valve, thereby increasing the pressure of the oil output from the first oil port of the second valve.When the second valve 82 has just switched from the first valve position to the second valve position, and the third valve has not yet switched to the first valve position, after the valve core of the second valve 82 continues to move a first distance in the first direction, that is, after the pressure difference between the first oil port of the second valve and the third oil port of the second valve decreases to the first pressure difference (the value of the first pressure difference is equal to the oil pressure at the third oil port of the second valve minus the oil pressure at the first oil port of the second valve), that is, when the pressure of the oil input at the first port remains unchanged, and the pressure of the oil output at the first oil port of the second valve increases to the first threshold, the third valve switches to the first valve position.

[0034] The handle assembly is configured such that pressing down on the first end of the connector 84 compresses the first compression spring 841, which in turn pushes the first valve 81 to its second position; pressing down on the second end of the connector 84 compresses the second compression spring 842, which in turn pushes the second valve 82 to its second position. This configuration ensures that when one of the first and second compression springs is compressed, the other remains uncompressed, preventing the first and second valves from simultaneously switching to their second positions. This prevents interference with the control assembly's position control of the directional valve, resulting in clear and reliable control. The operator can directly contact either the first or second end of the connector, or the first or second end can be rigidly connected to other components, allowing the operator to indirectly press down on the first or second end of the connector by pressing other components.

[0035] In the first operating state, the first valve 81 is in the second valve position, and the second valve 82 is in the first valve position. In the second operating state, the first valve 81 is in the first valve position, the second valve 82 is in the second valve position, and the third valve 83 is in the second valve position. In the third operating state, the first valve 81 is in the first valve position, the second valve 82 is in the second valve position, and the third valve 83 is in the first valve position. The oil output from the first port of the third valve compresses the valve core of the first valve 81, which in turn presses the connecting member 84, and the connecting member 84 presses the second compression spring 842, thus keeping the third valve 83 in the first valve position. When the first valve is in the second valve position and the second valve 82 is in the first valve position, the oil input from the first port is output from the first port of the first valve and output through the third port to control the directional valve, causing the directional valve to switch to the first valve position. When the first valve is in the first valve position, the second valve 82 is in the second valve position, and the third valve 83 is in the third valve position, the oil input from the first port is output from the first port of the second valve and output through the fourth port to control the directional valve. When the pressure of the oil output from the first port of the second valve is less than the first threshold, the oil output from the first port of the second valve causes the directional valve to switch to the second valve position. When the first valve is in its first position, the second valve 82 is in its second position, and the third valve 83 is in its first position, the oil input from the first port is output from the first port of the second valve and through the fourth port to control the directional valve. The pressure of the oil output from the first port of the second valve is not less than the first threshold. The oil output from the first port of the second valve causes the directional valve to switch to the third position, and the bulldozer blade cylinder enters the third working state. The bulldozer blade floats and rises. At this time, the oil output from the first port of the third valve causes the valve core of the first valve 81 to compress the first compression spring 841, and the first compression spring 841 presses the connecting piece 84 and the connecting piece 84 presses the second compression spring 842, so that the third valve 83 is kept in the first position and the bulldozer blade continues to work in a floating and rising state.

[0036] The bulldozer hydraulic system with a floating and lifting blade provided in this embodiment allows the bulldozer blade cylinder 13 to enter different working states by pressing down the end of the connecting member 84, thereby enabling the bulldozer blade to rise, fall, or float. Furthermore, when one end of the connecting member 84 is pressed down, the other end of the connecting member 84 will tilt upwards, preventing accidental operation of the first valve 81 and the second valve 82 to their second positions simultaneously, thus contributing to system safety. Simultaneously, after entering the third working state, the third valve in the switching device can output oil to provide hydraulic feedback to the valve core of the first valve, maintaining the first valve in its first position, the second valve in its second position, and the third valve in its third position, thereby enabling the bulldozer blade to effectively maintain a floating and lifting working state for extended periods.

[0037] In some embodiments, as shown in the figure, the bulldozing hydraulic system with a floating and lifting blade further includes a third spring 831. The third spring 831 is configured such that after the second valve 82 switches from the first valve position to the second valve position, the valve core of the second valve 82 will be resisted by the third spring 831 if it continues to move a first distance in the first direction and then continues to move in the first direction. The third spring 831 provides elastic resistance to the continued movement of the valve core of the second valve 82 in the first direction. The third spring 831 does not provide elastic resistance to the valve core of the second valve 82 before the valve core continues to move a first distance in the first direction, and does not affect the movement of the valve core. After the valve core of the second valve 82 continues to move a first distance in the first direction, the third valve switches to the first valve position, the reversing valve switches to the third valve position, and the bulldozer blade cylinder enters the third working state. At this time, the third spring 831 suddenly provides a large elastic resistance to the movement of the valve core of the second valve in the first direction, so that the operator suddenly feels an additional downward pressure resistance. It can be judged that the bulldozer blade cylinder has entered the third working state, so that there is a clear feeling when the bulldozer blade enters the floating lifting state.

[0038] In some embodiments, the third valve 83 further includes a fourth spring, the elastic force of which causes the valve core of the third valve 83 to move in a direction that causes the third valve 83 to switch to the second valve position.

[0039] In some embodiments, as shown in the figure, the first port of the first valve is connected to the first hydraulic control terminal. The pressure of the oil output from the first port of the first valve to the first hydraulic control terminal causes the valve core of the first valve 81 to tend to move in the direction that switches the first valve 81 to the first valve position. When the first valve is working in the second valve position, part of the oil output from the first port of the first valve is normally used for the control of the directional valve, and the other part is fed back to the first hydraulic control terminal. When the pressure of the oil output from the first port of the first valve increases abnormally, the pressure of the oil output from the first port of the first valve to the first hydraulic control terminal causes the valve core of the first valve 81 to move in the direction that switches to the first valve position, thereby reducing the oil pressure output from the first port of the first valve and ensuring system safety.

[0040] In some embodiments, the second valve 82 includes a second hydraulic control terminal, and a first port of the second valve is connected to the second hydraulic control terminal. The pressure of the oil output from the first port of the second valve to the second hydraulic control terminal causes the valve core of the second valve 82 to tend to move in a direction opposite to the first direction. When the second valve is operating in the second valve position, part of the oil output from the first port of the second valve is normally used for the control of the directional valve, and the other part is fed back to the first hydraulic control terminal. When the pressure of the oil output from the first port of the second valve increases abnormally, the pressure of the oil output from the first port of the second valve to the second hydraulic control terminal causes the valve core of the second valve 82 to move in the direction of switching to the first valve position, thereby reducing the oil pressure output from the first port of the second valve and ensuring system safety.

[0041] In some embodiments, a pressure reducing valve 9 is further included, connected between the working pump 11 and the first port, with the oil outlet of the pressure reducing valve 9 connected to the first port. The oil output from the working pump 11 is pressure reduced and then output to the first port, thereby providing the first port with oil of appropriate and stable pressure.

[0042] In some embodiments, such as Figure 1 As shown, the hydraulic control terminals of the directional control valve 23 include a third hydraulic control terminal and a fourth hydraulic control terminal located on opposite sides. The third port is connected to the third hydraulic control terminal, and the fourth port is connected to the fourth hydraulic control terminal. When the pressure of the oil output from the third port is greater than a first threshold, the oil output from the third port pushes the valve core of the directional control valve 23 to move to the position where the directional control valve 23 switches to the first valve position. When the pressure of the oil output from the fourth port is greater than a second threshold and less than a third threshold, the oil output from the fourth port pushes the valve core of the directional control valve 23 to move to the position where the directional control valve 23 switches to the second valve position. In some embodiments, the second threshold and the first threshold are the same. When the pressure of the oil output from the fourth port is greater than the third threshold, the oil output from the fourth port pushes the valve core of the directional control valve 23 to move to the position where the directional control valve 23 switches to the third valve position. In the embodiment shown in the figure, the directional control valve is a three-position six-way hydraulically controlled directional control valve.

[0043] In some embodiments, the bulldozer blade cylinder 13 includes a first oil chamber and a second oil chamber. In a first operating state, the reversing valve 23 controls the oil output from the working pump 11 to enter the first oil chamber and controls the oil output from the second oil chamber to the oil tank 17. In a second operating state, the reversing valve 23 controls the oil output from the working pump 11 to enter the second oil chamber and controls the oil output from the first oil chamber to the oil tank 17. In a third operating state, the reversing valve 23 controls both the first and second oil chambers to be simultaneously connected to the oil tank 17. In the embodiment shown in the figure, the first oil chamber is a rodless chamber B, and the second oil chamber is a rod-type chamber A. The switching device includes a reversing control valve group 2, which includes a reversing valve 23, a pressure compensation valve 22, and an unloading valve 21. The working pump 11 is a load-sensitive pump, which includes a load feedback regulating device. The feedback pipeline includes a shuttle valve 6, a load pressure feedback pipeline 5, and a pilot pressure feedback pipeline 4. The rodless chamber B is connected to the B1 port of the control valve group 2, and the rod chamber A is connected to the A1 port of the control valve group 2. The outlet of the load-sensitive pump is connected to the P1 port of the control valve group 2. The shuttle valve 6 is connected to the pressure feedback port PL of the load-sensitive pump. The load pressure feedback pipeline 5 is connected to both the shuttle valve 6 and the LS port of the control valve group 2. The pilot pressure feedback pipeline 4 is connected to both the shuttle valve 6 and the fourth port. The load-sensitive pump outputs high-pressure oil according to the load pressure feedback, which is sent to the bulldozer blade cylinder through the reversing valve 23 to further control the bulldozer blade's rising, falling, and floating lifting. Pilot pressure feedback line 4 and load pressure feedback line 5 are connected to the pressure feedback PL port of the load-sensitive pump via shuttle valve 6. When the excavator's bulldozer blade is using the floating lifting function for trench backfilling and site leveling, the load pressure PLS is greater than the pilot pressure Pbls. The LS port of the load pressure feedback line 5 is connected to the PL port of the load-sensitive pump to ensure load pressure feedback under normal operating conditions and control the pressure and flow output of the load-sensitive pump.

[0044] In some embodiments, an excavator is also disclosed, including a bulldozer blade and a bulldozing hydraulic system for floating and lifting any of the bulldozer blades described.

[0045] 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 preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A bulldozing hydraulic system with a floating and lifting bulldozer blade, characterized in that, It has a first working state, a second working state, and a third working state, including: tank; Working pump; A bulldozer blade cylinder is used to connect with a bulldozer blade. The bulldozer blade cylinder raises the bulldozer blade in one of the first working states and the second working states, and lowers the bulldozer blade in the other working state. The bulldozer blade cylinder causes the bulldozer blade to float up and down in the third working state. A switching device includes a control component and a reversing valve. The reversing valve is connected between the working pump, the oil tank, and the bulldozer cylinder, and is used to control the flow direction of the oil between the working pump, the oil tank, and the bulldozer cylinder. In a first operating state, the reversing valve is in a first valve position; in a second operating state, the reversing valve is in a second valve position; and in a third operating state, the reversing valve is in a third valve position. The control component includes a handle assembly, a first valve, a second valve, a third valve, a first port connected to the working pump, a second port connected to the oil tank, and a third port and a fourth port connected to the hydraulic control end of the reversing valve. The control component is used to adjust the pressure of the oil output from the third port and the fourth port to make the reversing valve in the first valve position. Switching between the second valve position and the third valve position; the first valve includes a first hydraulic control end, a first hydraulic control port disposed on the first hydraulic control end, a first spring, a first valve first port, a first valve second port, and a first valve third port; the second valve includes a second spring, a second valve first port, a second valve second port, and a second valve third port; the third valve includes a third valve first port, a third valve second port, and a third valve third port; the third valve first port is connected to the first hydraulic control port, the third valve second port is connected to the second valve first port, and the third valve third port is connected to the second port; the first valve first port is connected to the third port, the second valve first port is connected to the fourth port, and the first valve second port is connected to the... The second valve has a second oil port connected to the second port, and the first valve has a third oil port connected to the third oil port of the second valve and the first port; the handle assembly includes a frame, a connector hinged to the frame in the middle, a first compression spring disposed between the first end of the connector and the first valve, and a second compression spring disposed between the second end of the connector and the second valve, the first compression spring and the second compression spring being located on the same side of the connector; the first valve has a first valve position where the first valve's first oil port and the first valve's second oil port communicate, and a first valve position where the first valve's first oil port and the first valve's third oil port communicate, the elastic force of the first spring causing the valve core of the first valve to tend towards the first valve's... The valve moves in the direction of switching to the first valve's first position; the second valve has a second valve's first position where the second valve's first oil port and second valve's second oil port are connected, and a second valve's second position where the second valve's first oil port and second valve's third oil port are connected; the elastic force of the second spring causes the valve core of the second valve to tend to move in the direction of switching the second valve to the second valve's first position; the third valve has a third valve's first position where the third valve's first oil port and third valve's second oil port are connected, and the valve core of the third valve is drivenly connected to the valve core of the second valve; when the second valve is in the second valve's first position, the third valve is in the third valve's second position;When the second valve switches from the first valve position to the second valve position, the valve core of the second valve moves along a first direction; when the third valve switches from the second valve position to the first valve position, the valve core of the third valve moves along a second direction; when the valve core of the second valve moves along the first direction, the valve core of the third valve is driven by the valve core of the second valve to move along the second direction; after the second valve switches from the first valve position to the second valve position, the valve core of the second valve can continue to move along the first direction to increase the flow area between the first port and the third port of the second valve, and after the valve core of the second valve continues to move a first distance along the first direction, the third valve switches from the second valve position to the first valve position; the handle assembly is configured such that: pressing down the first end of the connector can compress the first compression spring and push the first valve to switch via the first compression spring. When switching to the second valve position of the first valve, the second compression spring can be compressed by pressing down the second end of the connecting member, and the second valve can be switched to the second valve position by the second compression spring. In the first working state, the first valve is in the second valve position and the second valve is in the first valve position. In the second working state, the first valve is in the first valve position, the second valve is in the second valve position, and the third valve is in the second valve position. In the third working state, the first valve is in the first valve position, the second valve is in the second valve position, and the third valve is in the first valve position, and the oil output from the first port of the third valve causes the valve core of the first valve to compress the first compression spring, and the first compression spring presses the connecting member and the connecting member presses the second compression spring, so that the third valve is held in the first valve position.

2. The floating and lifting bulldozing hydraulic system of the bulldozer blade as described in claim 1, characterized in that, It also includes a third spring, which is configured such that after the second valve switches from the first valve position to the second valve position, the valve core of the second valve moves a first distance in the first direction and its continued movement in the first direction is subject to the elastic resistance provided by the third spring.

3. The floating and lifting bulldozing hydraulic system of the bulldozer blade as described in claim 1, characterized in that, The third valve also includes a fourth spring, the elastic force of which causes the valve core of the third valve to tend to move in the direction that switches the third valve to the second valve position.

4. The floating and lifting bulldozing hydraulic system of the bulldozer blade as described in claim 1, characterized in that, The first port of the first valve is connected to the first hydraulic control terminal. The pressure of the oil output from the first port of the first valve to the first hydraulic control terminal causes the valve core of the first valve to tend to move in the direction that causes the first valve to switch to the first valve position.

5. The floating and lifting bulldozing hydraulic system of the bulldozer blade as described in claim 1, characterized in that, The second valve includes a second hydraulic control terminal. The first oil port of the second valve is connected to the second hydraulic control terminal. The pressure of the oil output from the first oil port of the second valve to the second hydraulic control terminal causes the valve core of the second valve to tend to move in a direction opposite to the first direction.

6. The floating and lifting bulldozing hydraulic system of claim 1, characterized in that, It also includes a pressure reducing valve connected between the working pump and the first port, the oil outlet of the pressure reducing valve being connected to the first port.

7. The floating and lifting bulldozing hydraulic system of claim 1, characterized in that, The hydraulic control terminals of the directional control valve include a third hydraulic control terminal and a fourth hydraulic control terminal located on opposite sides. The third port is connected to the third hydraulic control terminal, and the fourth port is connected to the fourth hydraulic control terminal. When the pressure of the oil output from the third port is greater than a first threshold, the oil output from the third port pushes the valve core of the directional control valve to move to the position where the directional control valve switches to the first valve position. When the pressure of the oil output from the fourth port is greater than a second threshold and less than a third threshold, the oil output from the fourth port pushes the valve core of the directional control valve to move to the position where the directional control valve switches to the second valve position. When the pressure of the oil output from the fourth port is greater than a third threshold, the oil output from the fourth port pushes the valve core of the directional control valve to move to the position where the directional control valve switches to the third valve position.

8. The floating and lifting bulldozing hydraulic system of claim 7, characterized in that, The bulldozer blade cylinder includes a first oil chamber and a second oil chamber. In a first working state, the reversing valve controls the oil output from the working pump to be input into the first oil chamber and controls the oil output from the second oil chamber to be output into the oil tank. In a second working state, the reversing valve controls the oil output from the working pump to be input into the second oil chamber and controls the oil output from the first oil chamber to be output into the oil tank. In a third working state, the reversing valve controls the first oil chamber and the second oil chamber to be simultaneously connected to the oil tank.

9. An excavator, characterized in that, Includes a bulldozer blade and a bulldozer hydraulic system with a floating and lifting capability for the bulldozer blade as described in any one of claims 1 to 8.

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