Hydraulic system for engineering machinery and engineering machinery

Abstract

The utility model relates to a hydraulic system for engineering machinery, which comprises a hydraulic oil tank, a working valve in fluid connection with the hydraulic oil tank, a working oil cylinder in fluid connection with the working valve and a pilot valve, the working oil cylinder comprises a rod cavity and a rodless cavity, and the pilot valve is in fluid connection with a pilot pressure control port of the working valve. The pilot valve is provided with an ascending position, a descending position and a floating position, and when the pilot valve is located at the ascending position, the working valve is switched to the ascending working position; when the pilot valve is in the descending position, the working valve is switched to the descending working position; the hydraulic system further comprises a hydraulic control one-way valve, an oil inlet of the hydraulic control one-way valve is in fluid connection with the hydraulic oil tank, an oil outlet of the hydraulic control one-way valve is in fluid connection with a rod cavity of the working oil cylinder, and a control oil port of the hydraulic control one-way valve is in fluid connection with the pilot valve. And an oil inlet and an oil outlet of the hydraulic control one-way valve are in fluid communication. The utility model further relates to engineering machinery comprising the hydraulic system.

Description

Technical Field

[0001] This utility model relates to the field of engineering machinery, and more specifically to a hydraulic system for engineering machinery and an engineering machinery including the hydraulic system. Background Technology

[0002] Some construction machinery, such as loaders and bulldozers, has a floating function, which allows the working implements (such as the bucket of a loader and the bulldozer blades) to descend with their own weight through a control device.

[0003] The floating function of construction machinery is mainly achieved by fluidly connecting the rod-side chamber, rodless chamber, and hydraulic tank of the working cylinder. Currently, there are two main methods for realizing the floating function.

[0004] The first option uses a four-position six-way valve as the working valve. This working valve has a lowering position, an upper position, a neutral position, and a floating position. When the working valve is in the floating position, both the rod-side chamber and the rodless chamber of the working cylinder are in fluid communication with the hydraulic oil tank, thereby realizing the floating function.

[0005] The second approach uses a working valve assembly with a pilot valve equipped with a hydraulically controlled check valve, paired with a pilot valve containing a sequence valve. When the sequence valve in the pilot valve is closed, the hydraulically controlled check valve cannot open because its outlet is sealed. When the sequence valve in the pilot valve opens, the outlet of the hydraulically controlled check valve is connected to the hydraulic oil tank via the sequence valve. The working fluid can easily open the hydraulically controlled check valve, thereby connecting the rod-side and rodless sides of the working cylinder to the hydraulic oil tank, achieving the floating function.

[0006] Both of these approaches require complex machining of the valve core of the working valve, which places extremely high demands on the machining of the valve core. It not only requires high-precision manufacturing processes, but also requires consideration of the selection of valve core materials and their wear resistance to ensure the stability, reliability and long-term use of the floating function.

[0007] The present invention aims to solve at least one of the above-mentioned problems in the prior art, as well as other problems. Utility Model Content

[0008] According to one aspect of the present invention, a hydraulic system for engineering machinery is provided, the hydraulic system comprising:

[0009] Hydraulic oil tank,

[0010] The working valve is fluidly connected to the hydraulic oil tank.

[0011] The working cylinder is fluidly connected to the working valve, and the working cylinder includes a rod-side chamber and a rodless chamber.

[0012] The pilot valve is fluidly connected to the pilot pressure control port of the working valve. The pilot valve has three positions: rising, falling, and floating.

[0013] When the pilot valve is in the raised position, the working valve is switched to the raised working position;

[0014] When the pilot valve is in the lowered position, the working valve is switched to the lowered working position;

[0015] Its features are,

[0016] The hydraulic system also includes a pilot-operated check valve, the inlet of which is fluidly connected to the hydraulic oil tank, the outlet of which is fluidly connected to the rod chamber of the working cylinder, and the control port of which is fluidly connected to the pilot valve.

[0017] When the pilot valve is in the floating position, the working valve is in the descending working position, and the oil inlet and outlet of the hydraulic check valve are in fluid communication.

[0018] Advantageously,

[0019] The first port of the pilot valve is fluidly connected to the first pilot pressure control port of the working valve via the first pilot oil passage;

[0020] The second port of the pilot valve is fluidly connected to the second pilot pressure control port of the working valve via the second pilot oil passage;

[0021] The control port of the hydraulic check valve is fluidly connected to the first pilot oil circuit.

[0022] When the pilot valve is in the down position, the pilot fluid reaches the first pilot pressure control port of the working valve via the first pilot oil circuit;

[0023] When the pilot valve is in the raised position, the pilot fluid reaches the second pilot pressure control port of the working valve through the second pilot oil circuit;

[0024] When the pilot valve is in the floating position, the pilot fluid reaches the first pilot pressure control port of the working valve through the first pilot oil circuit.

[0025] Advantageously,

[0026] The pilot pressure provided by the pilot valve when it is in the floating position is greater than the pilot pressure provided when it is in the descending position.

[0027] When the pilot valve is in the floating position, the pilot pressure provided matches the opening pressure of the pilot-operated check valve.

[0028] Advantageously, the pilot valve is configured such that the valve spool of the pilot valve continues to move in the same direction after reaching the end of the descending position, thereby moving the pilot valve to the floating position.

[0029] Advantageously, the position switching of the pilot valve can be achieved by means of a control device, which may be a pilot handle, control button, touch screen, or portable control terminal.

[0030] Advantageously,

[0031] When the working valve is in the raised working position, the hydraulic fluid can be delivered to the rodless chamber of the working cylinder through the working valve, and the hydraulic fluid in the rod chamber of the working cylinder can return to the hydraulic oil tank through the working valve.

[0032] When the working valve is in the lowered working position, hydraulic fluid can be delivered to the rod chamber of the working cylinder through the working valve, and the hydraulic fluid in the rodless chamber of the working cylinder can return to the hydraulic oil tank through the working valve.

[0033] Advantageously, when the pilot valve is in the rising and falling positions, the fluid flow to the inlet and outlet of the hydraulic check valve is disconnected.

[0034] Advantageously, the working valve and the hydraulic check valve are integrated into a single valve block.

[0035] According to another aspect of the present invention, an engineering machine is provided, wherein the engineering machine includes a hydraulic system according to the present invention.

[0036] Advantageously, the construction machinery is a loader.

[0037] The hydraulic system according to this invention achieves floating functionality simply by using a hydraulically controlled check valve. This design not only significantly improves the traditional implementation of floating functionality but also greatly reduces the processing difficulty and complexity of the working valve. Through this design, production costs are effectively saved while further enhancing the reliability and durability of the working valve, ensuring stable operation of the hydraulic system under various working conditions. Attached Figure Description

[0038] The present invention will now be described in more detail with reference to the illustrative accompanying drawings. The drawings and corresponding embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Wherein:

[0039] Figure 1 A schematic diagram of a hydraulic system for engineering machinery according to a preferred embodiment of the present invention is shown.

[0040] List of reference numerals in the attached diagram:

[0041] 1. Hydraulic oil tank 2. Working valve

[0042] 3. Working cylinder; 4. Pilot valve

[0043] 5 First pilot oil circuit 6 Second pilot oil circuit

[0044] 7 First pilot pressure control port 8 Second pilot pressure control port

[0045] 9. Hydraulic control check valve 100. Hydraulic system. Detailed Implementation

[0046] Embodiments of the present invention are described below with reference to the accompanying drawings. In the following description, numerous specific details are set forth to enable those skilled in the art to more fully understand and implement the present invention. However, it will be apparent to those skilled in the art that implementations of the present invention may not include some of these specific details. Furthermore, it should be understood that the present invention is not limited to the specific embodiments described. Rather, the present invention can be conceived to be implemented with any combination of the features and elements described below, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments, and advantages are for illustrative purposes only and should not be construed as elements or limitations of the claims unless expressly set forth in the claims.

[0047] Figure 1 This schematic diagram illustrates the hydraulic principle of a hydraulic system 100 for construction machinery according to a preferred embodiment of the present invention. The hydraulic system 100 is suitable for any construction machinery or other type of machinery with a floating function, such as loaders, bulldozers, etc.

[0048] like Figure 1 As shown, the hydraulic system 100 includes a hydraulic oil tank 1, a working valve 2 fluidly connected to the hydraulic oil tank 1, a working cylinder 3 fluidly connected to the working valve 2, and a pilot valve 4. The working cylinder 3 includes a rod chamber and a rodless chamber. In the case of a loader, the working cylinder 3 is the boom cylinder. The pilot valve 4 is fluidly connected to pilot pressure control ports located at both ends of the valve core of the working valve 2. Specifically, the first port of the pilot valve 4 ( Figure 1 The pilot valve 4 (left side) is fluidly connected to the first pilot pressure control port 7 of the working valve 2 via the first pilot oil passage 5, and the second port of the pilot valve 4 ( Figure 1 The right side of the valve is fluidly connected to the second pilot pressure control port 8 of the working valve 2 via the second pilot oil circuit 6.

[0049] Pilot valve 4 has an upward position, a downward position, and a floating position.

[0050] When pilot valve 4 is in the rising position, the pilot fluid from pilot valve 4 reaches the second pilot pressure control port 8 of working valve 2 via the second pilot oil circuit 6, switching working valve 2 to the rising working position. Figure 1(As shown on the right), at this time, for example, hydraulic fluid pumped from hydraulic tank 1 by working pump (not shown) can be delivered to rodless chamber of working cylinder 3 via working valve 2, and hydraulic fluid in rod chamber of working cylinder 3 can return to hydraulic tank 1 via working valve 2, thereby realizing the lifting operation of working implement (e.g., bucket) associated with working cylinder 3.

[0051] When pilot valve 4 is in the lowered position, the pilot fluid from pilot valve 4 reaches the first pilot pressure control port 7 of working valve 2 via the first pilot oil passage 5, switching working valve 2 to the lowered working position. Figure 1 (As shown in the left position), at this time, for example, hydraulic fluid pumped from hydraulic tank 1 by working pump (not shown) can be delivered to the rod chamber of working cylinder 3 via working valve 2, and the hydraulic fluid in the rodless chamber of working cylinder 3 can return to hydraulic tank 1 via working valve 2, thereby realizing the lowering operation of the working implement (e.g., bucket) associated with working cylinder 3.

[0052] According to this utility model, the hydraulic system 100 further includes a pilot-operated check valve 9. The inlet of the pilot-operated check valve 9 is fluidly connected to the hydraulic oil tank 1, the outlet of the pilot-operated check valve 9 is fluidly connected to the rod chamber of the working cylinder 3, and the control port of the pilot-operated check valve 9 is fluidly connected to the pilot valve 4. When a specific pilot pressure is reached at the control port, the pilot-operated check valve 9 can switch from a closed position where its inlet and outlet are fluidly disconnected to an open position where its inlet and outlet are fluidly connected. This switching can be achieved, for example, by setting the pilot valve 4 to output a pilot pressure that matches the opening pressure of the pilot-operated check valve 9 when it is in the floating position.

[0053] According to this invention, when the pilot valve 4 is in the floating position, the working valve 2 is in the lowered working position, and the inlet and outlet of the hydraulic check valve 9 are in fluid communication. At this time, the rodless chamber of the working cylinder 3 is in fluid communication with the hydraulic oil tank 1 via the working valve 2, and the rod chamber of the working cylinder 3 is in fluid communication with the hydraulic oil tank 1 via the hydraulic check valve 9. Therefore, both the rod chamber and the rodless chamber of the working cylinder 3 are in fluid communication with the hydraulic oil tank 1, thereby realizing the floating function.

[0054] exist Figure 1 In the illustrated embodiment, the control port of the hydraulic check valve 9 is fluidly connected to the first pilot oil circuit 5. When the pilot valve 4 is in the floating position, the pilot fluid reaches the first pilot pressure control port 7 of the working valve 2 via the first pilot oil circuit 5, and at the same time, the pilot fluid reaches the control port of the hydraulic check valve 9 from the first pilot oil circuit 5.

[0055] Advantageously, the pilot pressure provided by pilot valve 4 when it is in the floating position is greater than the pilot pressure provided when it is in the descending position. According to this arrangement, when pilot valve 4 is in the descending position, the pilot pressure in the first pilot oil circuit 5 is insufficient to switch the hydraulic check valve 9 from its closed position (where its inlet and outlet are fluidly disconnected) to its open position (where its inlet and outlet are fluidly connected). Instead, it only switches the working valve 2 to the descending working position, realizing the descending operation of the working tool. At this time, the inlet and outlet of the hydraulic check valve 9 are fluidly disconnected. When pilot valve 4 is in the floating position, the pilot pressure in the first pilot oil circuit 5, on the one hand, switches the working valve 2 to the descending working position or keeps the working valve 2 in the descending working position, and on the other hand, switches the hydraulic check valve 9 from its closed position (where its inlet and outlet are fluidly disconnected) to its open position (where its inlet and outlet are fluidly connected), realizing the floating function.

[0056] Advantageously, the spool displacement of pilot valve 4 in the floating position is greater than that in the descending position, thereby enabling the hydraulic check valve 9 to open through an increased pilot pressure. For example, pilot valve 4 is configured such that after its spool reaches the end of the descending position, it continues to advance a small displacement in the same direction to the floating position, thereby outputting a larger, specific pilot pressure to open the hydraulic check valve 9.

[0057] The position switching of pilot valve 4 can be achieved by means of a control device. This control device is, for example, a pilot handle. When the pilot handle is moved toward the descending position of pilot valve 4, after reaching the end of the descending position, continuing to move the pilot handle a small distance in the same direction will reach the floating position of pilot valve 4.

[0058] Advantageously, the control device can also be a mechanical control button, a touch screen, a portable control terminal, or other control device. Control buttons, for example, are located on the control panel in the cab of the construction machinery.

[0059] Advantageously, the working valve 2 and the pilot-operated check valve 9 can be integrated into a single valve block. Alternatively, it is also conceivable to house the working valve 2, the pilot-operated check valve 9, and the pilot valve 4 all within a single valve block.

[0060] In the hydraulic system 100 according to this utility model, the floating function is simply achieved by means of a hydraulically controlled check valve 9. This design not only significantly improves the traditional implementation of the floating function, but also greatly reduces the processing difficulty and complexity of the working valve. Through this design, while effectively saving production costs, the reliability and durability of the working valve are further enhanced, ensuring the stable operation of the hydraulic system under various working conditions.

[0061] Industrial applicability

[0062] The working principle of the hydraulic system 100 according to this utility model is explained in detail below. This hydraulic system 100 is particularly suitable for loaders and bulldozers. It is understood that the hydraulic system 100 is also suitable for other construction machinery or other types of machinery with similar working conditions (i.e., with floating functionality).

[0063] When the operator of the construction machinery moves the pilot valve 4 to the raised position using the pilot handle or other control device, the pilot fluid reaches the second pilot pressure control port 8 of the working valve 2 via the second pilot oil circuit 6, switching the working valve 2 to the raised working position. Figure 1 (As shown on the right), it enables the lifting operation of the working tool (e.g., bucket) associated with the working cylinder 3.

[0064] When the operator of the construction machinery moves the pilot valve 4 to the lowered position, the pilot fluid reaches the first pilot pressure control port 7 of the working valve 2 via the first pilot oil circuit 5, switching the working valve 2 to the lowered working position. Figure 1 (As shown on the left), it enables the lowering operation of the working tool (e.g., bucket) associated with the working cylinder 3.

[0065] When the operator of the construction machinery moves the pilot valve 4 to the floating position, the working valve 2 is in the lowered working position. At the same time, the pilot fluid from the pilot valve 4 connects the oil inlet and outlet of the hydraulic control check valve 9, so that the rod chamber and rodless chamber of the working cylinder 3 are connected to the hydraulic oil tank 1, thereby realizing the floating function.

[0066] The hydraulic system of this utility model has been described above with reference to specific embodiments. It will be apparent to those skilled in the art that various changes and modifications can be made to the hydraulic system of this utility model without departing from the design principles of this utility model. For example, embodiments of this utility model may not include some of the features described, and this utility model is not limited to the described specific embodiments, but any combination of the described features and elements is conceivable. Other embodiments will be apparent to those skilled in the art in light of consideration of the specification and practice with the disclosed hydraulic system. The specification and examples are to be considered exemplary only, and the true scope is indicated by the appended claims and their equivalents.

Claims

1. A hydraulic system for a working machine, the hydraulic system comprising: a hydraulic tank (1), a work valve (2) in fluid connection with the hydraulic tank (1), a work cylinder (3) in fluid connection with the work valve (2), the work cylinder comprising a rod cavity and a rodless cavity, and a pilot valve (4) in fluid connection with a pilot pressure control port of the work valve, the pilot valve having a raised position, a lowered position and a floating position, wherein the work valve is switched to a raised work position when the pilot valve is in the raised position; the work valve is switched to a lowered work position when the pilot valve is in the lowered position; characterized in that the hydraulic system further comprises a hydraulic control check valve (9), an inlet port of the hydraulic control check valve being in fluid connection with the hydraulic tank, an outlet port of the hydraulic control check valve being in fluid connection with the rod cavity of the work cylinder, a control port of the hydraulic control check valve being in fluid connection with the pilot valve, wherein the inlet port and the outlet port of the hydraulic control check valve are in fluid communication when the pilot valve is in the floating position and the work valve is in the lowered work position.

2. The hydraulic system according to claim 1, characterized in that a first port of the pilot valve is in fluid connection with a first pilot pressure control port (7) of the work valve via a first pilot oil line (5); a second port of the pilot valve is in fluid connection with a second pilot pressure control port (8) of the work valve via a second pilot oil line (6); the control port of the hydraulic control check valve is in fluid connection with the first pilot oil line; pilot fluid reaches the first pilot pressure control port of the work valve via the first pilot oil line when the pilot valve is in the lowered position; pilot fluid reaches the second pilot pressure control port of the work valve via the second pilot oil line when the pilot valve is in the raised position; pilot fluid reaches the first pilot pressure control port of the work valve via the first pilot oil line when the pilot valve is in the floating position.

3. The hydraulic system according to claim 1 or 2, characterized in that the pilot pressure provided when the pilot valve is in the floating position is greater than the pilot pressure provided when the pilot valve is in the lowered position; the pilot pressure provided when the pilot valve is in the floating position matches the opening pressure of the hydraulic control check valve.

4. The hydraulic system of claim 3, wherein, the pilot valve is configured to enable the spool of the pilot valve to continue moving in the same direction after reaching the end of the lowered position, enabling the pilot valve to move to the floating position.

5. The hydraulic system of claim 1 or 2, wherein, the switching of the position of the pilot valve can be achieved by means of a control device, which is a pilot handle or a control button or a touch screen or a portable control terminal.

6. The hydraulic system according to claim 1 or 2, characterized in that when the work valve is in the raised work position, hydraulic fluid can be delivered to the rodless cavity of the work cylinder via the work valve, and hydraulic fluid in the rod cavity of the work cylinder can be returned to the hydraulic tank via the work valve; when the work valve is in the lowered work position, hydraulic fluid can be delivered to the rod cavity of the work cylinder via the work valve, and hydraulic fluid in the rodless cavity of the work cylinder can be returned to the hydraulic tank via the work valve.

7. The hydraulic system of claim 1 or 2, wherein, the inlet port and the outlet port of the hydraulic control check valve are fluidly disconnected when the pilot valve is in the raised and lowered positions.

8. The hydraulic system of claim 1 or 2, wherein, the work valve and the hydraulic control check valve are integrated in one valve block.

9. A working machine, characterized in that the working machine comprises the hydraulic system according to any one of claims 1 to 8.

10. A working machine according to claim 9, characterized by The working machine is a loader. The working machine is a loader.

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