Leveling hydraulic system and skid steer loader

Abstract

This utility model relates to the field of skid steer loader technology, and discloses a leveling hydraulic system and a skid steer loader. The leveling hydraulic system includes: a boom cylinder, a bucket cylinder, a power transmission assembly, a multi-way directional valve assembly, and a pilot assembly. The multi-way directional valve assembly has a first directional valve and a second directional valve. The first directional valve has a first valve core adjusting element, and the second directional valve has a second valve core adjusting element. The pilot assembly includes a first pilot valve and a proportional pressure reducing valve. The first pilot oil circuit and the second pilot oil circuit are connected. The proportional pressure reducing valve is set on the second pilot oil circuit. By setting the proportional pressure reducing valve on the second pilot oil circuit, the pressure ratio between its inlet and outlet can be kept constant. This allows the pilot oil pressure in the first pilot oil circuit and the second pilot oil circuit to be in a certain proportion, so that the extension of the bucket cylinder matches the lifting amount of the boom, thereby achieving the effect of automatic leveling.

Description

Technical Field

[0001] This utility model relates to the field of skid steer loader technology, specifically to a leveling hydraulic system and a skid steer loader. Background Technology

[0002] A skid steer loader is a small construction machine with a rigid frame. When the boom of a skid steer loader needs to be raised during loading operations, in order to reduce the occurrence of material falling during the working process, the bucket cylinder often needs to be operated frequently to keep the bucket in its own position during the boom lifting process. In order to improve work efficiency and avoid frequent operation by the operator, skid steer loaders are usually equipped with a drive system that can automatically level the bucket.

[0003] Currently, the boom and bucket of skid steer loaders are generally hydraulically driven. Existing hydraulic leveling of the bucket is mainly achieved by a leveling valve, which forces the hydraulic oil discharged from the rodless chamber of the boom cylinder to the large chamber of the bucket cylinder through the diverter valve of the leveling valve. By using the area ratio of the damping orifice in the diverter valve, the flow rate is sent to the bucket cylinder in a certain proportion. However, this leveling method is greatly affected by the engine speed and the specifications of the damping orifice. When the flow rate is insufficient, the phenomenon of delayed leveling is likely to occur. Utility Model Content

[0004] In view of this, the present invention provides a leveling hydraulic system and a skid steer loader to solve the problem of poor stability of the existing skid steer loader bucket hydraulic leveling method.

[0005] In a first aspect, this utility model provides a leveling hydraulic system, comprising: a boom cylinder, a bucket cylinder, a power transmission assembly, a multi-way directional valve assembly, and a pilot assembly; the multi-way directional valve assembly has a first directional valve and a second directional valve, the power transmission assembly is connected to the boom cylinder via the first directional valve, and the power transmission assembly is connected to the bucket cylinder via the second directional valve; the first directional valve has a first extension valve position for extending the boom cylinder and a first stop valve position for stopping conduction; the second directional valve has a second extension valve position for extending the bucket cylinder and a stop valve position. The second stop valve position is provided to prevent conduction. The first directional valve has a first valve core adjusting element, which is used to adjust the valve position of the first directional valve. The second directional valve has a second valve core adjusting element, which is used to adjust the valve position of the second directional valve. The pilot assembly includes a first pilot valve and a proportional pressure reducing valve. The first pilot valve is connected to the first valve core adjusting element through a first pilot oil passage. The first pilot valve is connected to the second valve core adjusting element through a second pilot oil passage. The first pilot oil passage and the second pilot oil passage are connected. The proportional pressure reducing valve is located on the second pilot oil passage.

[0006] Beneficial effects: By setting a proportional pressure reducing valve in the second pilot oil circuit, the pilot oil of corresponding pressure in the first pilot oil circuit can adjust the valve core of the first directional valve to have a corresponding opening degree through the first valve core adjusting component. Similarly, the pilot oil of corresponding pressure in the second pilot oil circuit can adjust the valve core of the second directional valve to have a corresponding opening degree through the second valve core adjusting component. Since the proportional pressure reducing valve can keep the pressure ratio between its inlet and outlet constant, it can make the pilot oil pressure in the first and second pilot oil circuits in a certain proportion. Therefore, the first and second directional valves can have a preset proportion of opening degree. Without the need for a leveling valve, it can ensure that the bucket cylinder extends synchronously with the boom as it is lifted, and that the extension amount of the bucket cylinder matches the lifting amount of the boom, thereby achieving an automatic leveling effect. This effectively solves the problem of poor stability of the existing skid steer loader bucket hydraulic leveling method.

[0007] In one alternative implementation, the power delivery assembly is a load-sensitive pump, and the multi-way directional valve assembly is a load-sensitive valve.

[0008] Beneficial effects: The load-sensitive pump and load-sensitive valve are equipped with a pressure compensation structure, which can provide hydraulic oil of the corresponding flow rate according to the system requirements. This can effectively reduce energy waste while making the response more sensitive and rapid.

[0009] In one alternative embodiment, the pilot assembly further includes a check valve disposed in the second pilot oil circuit and located between the proportional pressure reducing valve and the first pilot oil circuit, with the check valve being open toward the proportional pressure reducing valve.

[0010] Beneficial effects: The check valve can effectively restrict the flow direction of the pilot oil in the second pilot oil circuit and prevent the pilot oil in the second pilot oil circuit from flowing back.

[0011] In one alternative embodiment, the first directional valve further has a first retraction valve position for retracting the boom cylinder, and the first directional valve further has a third valve core adjusting member for adjusting the valve position of the first directional valve.

[0012] The pilot assembly also includes a second pilot valve, which is connected to the third valve core adjustment element through a third pilot oil passage.

[0013] Beneficial effect: The second pilot valve enables the leveling hydraulic system to achieve independent retraction of the boom cylinder.

[0014] In one alternative embodiment, the pilot assembly further includes a third pilot valve, which is connected to the portion of the second pilot oil circuit located at the proportional pressure reducing valve and the second valve core adjusting member.

[0015] Beneficial effect: This type of third pilot valve allows the leveling hydraulic system to achieve independent extension of the bucket cylinder.

[0016] In one alternative embodiment, the second directional valve further has a second retraction valve position for retracting the boom cylinder, and the second directional valve further has a fourth valve core adjusting member for adjusting the valve position of the second directional valve.

[0017] The pilot assembly also includes a fourth pilot valve, which is connected to a fourth valve core adjustment element through a fourth pilot oil circuit. A hydraulic control check valve is also provided between the third pilot valve and the second pilot oil circuit. The hydraulic control check valve is unidirectionally directed toward the second pilot oil circuit, and the hydraulic control structure of the hydraulic control check valve is connected to the fourth pilot oil circuit.

[0018] Beneficial effect: This type of fourth pilot valve allows the leveling hydraulic system to achieve independent retraction of the bucket cylinder.

[0019] In one alternative embodiment, the leveling hydraulic system further includes a pilot handle, which is connected to a first pilot valve, a second pilot valve, a third pilot valve, and a fourth pilot valve, respectively.

[0020] Beneficial effects: The opening of the corresponding pilot valve can be easily and quickly controlled by the pilot handle, thereby improving the operational flexibility of the leveling hydraulic system.

[0021] In one optional embodiment, the leveling hydraulic system further includes a pilot oil source, which is connected to a first pilot valve, a second pilot valve, a third pilot valve, and a fourth pilot valve, respectively.

[0022] Beneficial effects: Multiple pilot valves can be supplied with oil by a single pilot oil source, the structure is simple and reliable, and it is easy to process and manufacture.

[0023] In one optional embodiment, the leveling hydraulic system further includes a hydraulic oil tank, the oil inlet of the power transmission component is connected to the hydraulic oil tank, and the oil outlets of the first pilot valve, the second pilot valve, the third pilot valve and the fourth pilot valve are all connected to the hydraulic oil tank.

[0024] Beneficial effects: The hydraulic oil tank can provide hydraulic oil for the power transmission components and also accommodate the return oil from the pilot valve. It has a simple and reliable structure and is easy to process and manufacture.

[0025] Secondly, this utility model also provides a skid steer loader, which includes: a frame; and the aforementioned leveling hydraulic system, which is disposed on the frame. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the component connections of a leveling hydraulic system according to an embodiment of the present utility model;

[0028] Figure 2 for Figure 1 An enlarged schematic diagram of the pilot component of the leveling hydraulic system is shown.

[0029] Explanation of reference numerals in the attached figures:

[0030] 1. Boom cylinder;

[0031] 2. Bucket hydraulic cylinder;

[0032] 3. Power transmission components; 301. Valve core; 302. Variable displacement cylinder;

[0033] 4. Multi-way directional valve assembly; 401. First directional valve; 4011. First valve core adjusting component; 4012. Third valve core adjusting component; 402. Second directional valve; 4021. Second valve core adjusting component; 4022. Fourth valve core adjusting component; 403. First pressure compensation valve; 404. Second pressure compensation valve;

[0034] 5. Pilot assembly; 501. First pilot valve; 502. Ratio pressure reducing valve; 503. Check valve; 504. Second pilot valve; 505. Third pilot valve; 506. Fourth pilot valve; 507. Hydraulic check valve; 508. Pilot handle;

[0035] 6. First pilot oil circuit; 7. Second pilot oil circuit; 8. Third pilot oil circuit; 9. Fourth pilot oil circuit; 10. Pilot oil source; 11. Hydraulic oil tank. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0037] The following is combined Figure 1 and Figure 2 The following describes embodiments of the present invention.

[0038] According to an embodiment of the present invention, a leveling hydraulic system is provided, comprising: a boom cylinder 1, a bucket cylinder 2, a power transmission assembly 3, a multi-way directional valve assembly 4, and a pilot assembly 5;

[0039] The multi-way directional valve assembly 4 has a first directional valve 401 and a second directional valve 402. The power transmission assembly 3 is connected to the boom cylinder 1 through the first directional valve 401 and to the bucket cylinder 2 through the second directional valve 402. The first directional valve 401 has a first extension valve position for extending the boom cylinder 1 and a first stop valve position for stopping conduction. The second directional valve 402 has a second extension valve position for extending the bucket cylinder 2 and a second stop valve position for stopping conduction. The first directional valve 401 has a first valve core adjusting member 4011 for adjusting the valve position of the first directional valve 401. The second directional valve 402 has a second valve core adjusting member 4021 for adjusting the valve position of the second directional valve 402.

[0040] The pilot assembly 5 includes a first pilot valve 501 and a proportional pressure reducing valve 502. The first pilot valve 501 is connected to the first valve core adjusting member 4011 through the first pilot oil passage 6. The first pilot valve 501 is connected to the second valve core adjusting member 4021 through the second pilot oil passage 7. The first pilot oil passage 6 and the second pilot oil passage 7 are connected. The proportional pressure reducing valve 502 is disposed on the second pilot oil passage 7.

[0041] The leveling hydraulic system of this embodiment, by setting a proportional pressure reducing valve 502 on the second pilot oil circuit 7, allows the pilot oil of corresponding pressure in the first pilot oil circuit 6 to have a corresponding opening degree through the first valve core adjusting member 4011, and the pilot oil of corresponding pressure in the second pilot oil circuit 7 to have a corresponding opening degree through the second valve core adjusting member 4021. Since the proportional pressure reducing valve 502 can keep the pressure ratio between its inlet and outlet constant, it can make the pilot oil pressure in the first pilot oil circuit 6 and the second pilot oil circuit 7 in a certain proportion. Therefore, the first reversing valve 401 and the second reversing valve 402 can have a preset proportion of opening degree. Without using a leveling valve, it can ensure that the bucket cylinder 2 extends synchronously with the boom when it is lifted, and that the extension amount of the bucket cylinder 2 matches the lifting amount of the boom, thereby achieving the effect of automatic leveling. This effectively solves the problem of poor stability of the existing skid steer loader bucket hydraulic leveling method.

[0042] Specifically, there is no limitation on the specific types of the first reversing valve 401 and the second reversing valve 402. They can be hydraulically controlled reversing valves or electrically controlled reversing valves, and can be flexibly selected according to the requirements.

[0043] Furthermore, compared to the complex piping of the leveling valve machine connection, the leveling hydraulic system in this embodiment has a simpler structure. It adopts a hydraulic pilot circuit and can achieve the leveling function even without the use of an electronic control scheme that controls the controller program. Not only does it occupy less space during assembly, but it also has a lower structural complexity, which can effectively reduce the installation cost and production cost of the leveling hydraulic system, such as piping connection.

[0044] In one possible implementation, such as Figure 1 As shown, the power transmission component 3 is a load-sensitive pump, and the multi-way directional valve component 4 is a load-sensitive valve. The load-sensitive pump and the load-sensitive valve are equipped with a pressure compensation structure, which can provide hydraulic oil of corresponding flow rate according to the needs of the system. This can effectively reduce energy waste while making the response more sensitive and rapid.

[0045] Specifically, such as Figure 1 As shown, the frame indicated by the dotted line of the multi-way directional valve assembly 4 is divided into three frames arranged from left to right. The three frames are the oil inlet assembly, the boom assembly, and the bucket assembly. The boom assembly includes a first pressure compensation valve 403 and a first directional valve 401, and the bucket assembly includes a second pressure compensation valve 404 and a second directional valve 402.

[0046] In the multi-way directional valve assembly 4, the specific structures of the load-sensitive pump and the load-sensitive valve can be referenced from existing load-sensitive pumps and load-sensitive valves, and will not be elaborated on here.

[0047] In one possible implementation, the pilot assembly 5 further includes a one-way valve 503, which is disposed on the second pilot oil passage 7 and located between the proportional pressure reducing valve 502 and the first pilot oil passage 6. The one-way valve 503 is open to the proportional pressure reducing valve 502 and can effectively limit the flow direction of the pilot oil in the second pilot oil passage 7 to prevent the pilot oil in the second pilot oil passage 7 from flowing back.

[0048] Furthermore, when the valve core of the first pilot valve 501 opens, pilot oil enters the first pilot oil circuit 6, pushing the first valve core adjusting component 4011. The valve core of the first directional valve 401 moves upward, and the hydraulic oil delivered by the power transmission assembly 3 enters the rodless chamber of the boom cylinder 1 through the first directional valve 401, at which point the boom cylinder 1 extends. Simultaneously, pilot oil enters the second pilot oil circuit 7, and passes through the check valve 503 and then the proportional pressure reducing valve 502 in sequence. The pilot oil pushes the second valve core adjusting component 4021, causing the valve core of the second directional valve 402 to move upward. A portion of the hydraulic oil delivered by the power transmission assembly 3 enters the rodless chamber of the bucket cylinder 2, and the bucket cylinder 2 extends. At this time, the pressure oil at the LS port of the load-sensitive valve enters the right end of the valve core 301, pushing the valve core 301 to the right, causing the hydraulic oil in the variable cylinder 302 to flow out. The pump swashplate swings towards the larger displacement, allowing the load-sensitive pump to provide the required flow rate for the system and reducing energy waste.

[0049] In one possible implementation, the first directional valve 401 further has a first retraction valve position for retracting the boom cylinder 1, and the first directional valve 401 also has a third valve core adjusting member 4012 for adjusting the valve position of the first directional valve 401; the pilot assembly 5 further includes a second pilot valve 504, which is connected to the third valve core adjusting member 4012 through a third pilot oil passage 8. Through the second pilot valve 504, the leveling hydraulic system can realize the operation of retracting the boom cylinder 1 individually.

[0050] Specifically, such as Figure 1 and Figure 2 As shown, when the valve core of the second pilot valve 504 opens, the pilot oil enters the third pilot oil circuit 8 and pushes the third valve core adjusting component 4012. The valve core of the first directional valve 401 moves down, and the hydraulic oil delivered by the power transmission assembly 3 enters the rod chamber of the boom cylinder 1 through the first directional valve 401. At this time, the boom descends. Meanwhile, the second directional valve 402 has no pilot oil, so the second directional valve 402 does not work at this time, and no leveling is required during the boom descent.

[0051] In one possible implementation, the pilot assembly 5 further includes a third pilot valve 505, which is partially connected to the second pilot oil circuit 7 at the location of the proportional pressure reducing valve 502 and the second valve core adjusting member 4021. This type of third pilot valve 505 enables the leveling hydraulic system to perform the operation of the bucket cylinder 2 extending independently.

[0052] Specifically, the valve core of the third pilot valve 505 opens, and the pilot oil pushes the second valve core adjusting component 4021 through the second pilot oil circuit 7. The valve core of the second directional valve 402 moves upward, and the hydraulic oil delivered by the power transmission assembly 3 enters the rodless chamber of the bucket cylinder 2 through the valve core of the second directional valve 402. At this time, the bucket cylinder 2 extends. Due to the blocking effect of the check valve 503, the first directional valve 401 has no pilot oil, so the first directional valve 401 does not operate.

[0053] In one possible implementation, the second directional valve 402 also has a second retraction valve position for retracting the boom cylinder 1, and the second directional valve 402 also has a fourth valve core adjusting member 4022 for adjusting the valve position of the second directional valve 402.

[0054] The pilot assembly 5 also includes a fourth pilot valve 506, which is connected to the fourth valve core adjusting component 4022 via the fourth pilot oil passage 9. A hydraulic control check valve 507 is also provided between the third pilot valve 505 and the second pilot oil passage 7. The hydraulic control check valve 507 is unidirectionally directed toward the second pilot oil passage 7. The hydraulic control structure of the hydraulic control check valve 507 is connected to the fourth pilot oil passage 9. Through this type of fourth pilot valve 506, the leveling hydraulic system can realize the operation of retracting the bucket cylinder 2 independently.

[0055] Specifically, the valve core of the fourth pilot valve 506 is opened, and the pilot oil pushes the fourth valve core adjusting component 4022 through the fourth pilot oil circuit 9. The valve core of the second directional valve 402 moves downward. At this time, the valve core of the hydraulic control check valve 507 is opened. The hydraulic control check valve 507 will not block the return of the pilot oil at the second directional valve 402. The hydraulic oil delivered by the power transmission assembly 3 enters the rod chamber of the bucket cylinder 2 through the valve core of the second directional valve 402. The bucket cylinder 2 retracts. At this time, the first directional valve 401 has no pilot oil and does not move.

[0056] In one possible implementation, the leveling hydraulic system further includes a pilot handle 508, which is connected to a first pilot valve 501, a second pilot valve 504, a third pilot valve 505, and a fourth pilot valve 506, respectively. The opening of the corresponding pilot valve can be conveniently and quickly controlled through the pilot handle 508, thereby improving the operational flexibility of the leveling hydraulic system.

[0057] In one possible implementation, the leveling hydraulic system further includes a pilot oil source 10, which is connected to a first pilot valve 501, a second pilot valve 504, a third pilot valve 505, and a fourth pilot valve 506 respectively. A single pilot oil source 10 can supply oil to multiple pilot valves, resulting in a simple and reliable structure that is easy to manufacture.

[0058] In one possible implementation, the leveling hydraulic system further includes a hydraulic oil tank 11. The oil inlet of the power transmission component 3 is connected to the hydraulic oil tank 11. The oil outlets of the first pilot valve 501, the second pilot valve 504, the third pilot valve 505, and the fourth pilot valve 506 are all connected to the hydraulic oil tank 11. The hydraulic oil tank 11 can provide hydraulic oil to the power transmission component 3 and also accommodate the return oil from the pilot valves. It has a simple and reliable structure and is easy to process and manufacture.

[0059] According to an embodiment of the present invention, in another aspect, a skid steer loader is provided, comprising: a frame; and the aforementioned leveling hydraulic system disposed on the frame.

[0060] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A leveling hydraulic system characterized in that, include: Boom cylinder (1), bucket cylinder (2), power transmission assembly (3), multi-way directional valve assembly (4), and pilot assembly (5); The multi-way directional valve assembly (4) has a first directional valve (401) and a second directional valve (402). The power transmission assembly (3) is connected to the boom cylinder (1) through the first directional valve (401), and the power transmission assembly (3) is connected to the bucket cylinder (2) through the second directional valve (402). The first directional valve (401) has a first extension valve position for extending the boom cylinder (1) and a first stop valve position for stopping conduction. The second directional valve... (402) has a second extension valve position for extending the bucket cylinder (2) and a second stop valve position for stopping conduction. The first directional valve (401) has a first valve core adjusting member (4011) for adjusting the valve position of the first directional valve (401). The second directional valve (402) has a second valve core adjusting member (4021) for adjusting the valve position of the second directional valve (402). The pilot assembly (5) includes a first pilot valve (501) and a proportional pressure reducing valve (502). The first pilot valve (501) is connected to the first valve core adjusting member (4011) through a first pilot oil passage (6). The first pilot valve (501) is connected to the second valve core adjusting member (4021) through a second pilot oil passage (7). The first pilot oil passage (6) and the second pilot oil passage (7) are connected. The proportional pressure reducing valve (502) is disposed on the second pilot oil passage (7).

2. The leveling hydraulic system of claim 1, wherein, The power transmission component (3) is a load-sensitive pump, and the multi-way reversing valve component (4) is a load-sensitive valve.

3. Levelling hydraulic system according to claim 1 or 2, characterized in that, The pilot assembly (5) further includes a one-way valve (503), which is disposed on the second pilot oil circuit (7) and located between the proportional pressure reducing valve (502) and the first pilot oil circuit (6). The one-way valve (503) is open toward the proportional pressure reducing valve (502).

4. The leveling hydraulic system of claim 3, wherein, The first directional valve (401) also has a first retraction valve position for retracting the boom cylinder (1), and the first directional valve (401) also has a third valve core adjusting member (4012) for adjusting the valve position of the first directional valve (401). The pilot assembly (5) further includes a second pilot valve (504), which is connected to the third valve core adjuster (4012) through a third pilot oil passage (8).

5. The leveling hydraulic system of claim 4, wherein, The pilot assembly (5) further includes a third pilot valve (505), which is connected to the portion of the second pilot oil circuit (7) located in the constant ratio pressure reducing valve (502) and the second valve core adjusting member (4021).

6. The leveling hydraulic system of claim 5, wherein, The second directional valve (402) also has a second retraction valve position for retracting the boom cylinder (1), and the second directional valve (402) also has a fourth valve core adjusting member (4022) for adjusting the valve position of the second directional valve (402); The pilot assembly (5) further includes a fourth pilot valve (506), which is connected to the fourth valve core adjusting member (4022) through the fourth pilot oil passage (9). A hydraulic control check valve (507) is also provided between the third pilot valve (505) and the second pilot oil passage (7). The hydraulic control check valve (507) is unidirectionally connected to the second pilot oil passage (7), and the hydraulic control structure of the hydraulic control check valve (507) is connected to the fourth pilot oil passage (9).

7. The leveling hydraulic system of claim 6, wherein, The leveling hydraulic system also includes a pilot handle (508), which is connected to the first pilot valve (501), the second pilot valve (504), the third pilot valve (505), and the fourth pilot valve (506), respectively.

8. The leveling hydraulic system of claim 6, wherein, The leveling hydraulic system also includes a pilot oil source (10), which is connected to the first pilot valve (501), the second pilot valve (504), the third pilot valve (505), and the fourth pilot valve (506), respectively.

9. The leveling hydraulic system of claim 6, wherein, The leveling hydraulic system also includes a hydraulic oil tank (11), the oil inlet of the power transmission component (3) is connected to the hydraulic oil tank (11), and the oil outlets of the first pilot valve (501), the second pilot valve (504), the third pilot valve (505) and the fourth pilot valve (506) are all connected to the hydraulic oil tank (11).

10. A skid steer loader characterized by, include: body; The leveling hydraulic system according to any one of claims 1 to 9 is disposed on the machine body.

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