Anti-flameout hydraulic system of skid loader and skid loader
By improving the hydraulic system, including the coordination of shuttle valves and power valves, the problem of stalling of skid steer loaders when the load changes has been solved, achieving a low-cost and efficient anti-stalling effect and avoiding speed fluctuations and power lag.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANDONG KEN STONE HEAVY MACHINERY CO LTD
- Filing Date
- 2026-04-03
- Publication Date
- 2026-05-15
AI Technical Summary
Skid steer loaders are prone to stalling when the load changes. Existing anti-stalling technologies suffer from low efficiency, high cost, power lag, and speed fluctuations.
The system employs a hydraulic tank, tandem pump, left travel motor, right travel motor, shuttle valve, oil source valve, power valve, and multi-operation valve. Through the cooperation of the shuttle valve and the power valve, the probability of engine stalling is reduced, and the multi-operation valve is automatically adjusted when the load increases to avoid speed fluctuations and power lag.
It reduces the probability of engine stalling, is low-cost, easy to maintain and repair, has no speed fluctuations or vehicle jerking when the load increases, and has no power lag when turning at low speeds or driving at high speeds, forming an effective pressure protection system.
Smart Images
Figure CN122040697A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of skid steer loaders, and more particularly to a skid steer loader anti-stalling hydraulic system and a skid steer loader. Background Technology
[0002] Skid steer loaders are a common type of construction machinery. Also known as skid steer loaders, multi-purpose engineering vehicles, or multi-purpose engineering machines, skid steer loaders are wheeled specialized chassis equipment that uses the difference in linear speed between the wheels on both sides to achieve vehicle steering. They are mainly used in situations where the work area is confined, the ground is uneven, and the work content changes frequently.
[0003] Skid steer loaders are widely used in various industrial and agricultural projects due to their relatively compact size, ease of operation, and adaptability to production. However, this also means that skid steer loaders need to be adaptable to various complex road conditions. For example, when a skid steer loader is going uphill, the hydraulic load feedback can affect the engine, causing engine overload and potentially leading to engine stalling.
[0004] Currently, the anti-stalling measures for skid steer loaders are DA power matching control + idle speed boost or DA + electronic control.
[0005] Among them, the DA power matching control + idle speed increase is achieved by sensing the engine speed through the DA valve. When the hydraulic load causes the engine speed to drop, the swashplate angle of the series pump will be automatically reduced to decrease the displacement and reduce the hydraulic system's occupation of engine torque, while increasing the engine idle speed.
[0006] Among them, DA+electronic control combines intelligent decision-making of electronic control with power matching control of DA, and is divided into three types: electronic control-led, DA-led, and collaborative mechanism.
[0007] However, the drawbacks of DA+ idle speed enhancement are that, to ensure the anti-stalling function, the system reserves a lot of power redundancy, resulting in lower efficiency during operation. During sudden load changes, engine speed fluctuations and vehicle jerking may occur. When transitioning from low speed to high speed, power lag may occur due to the sudden increase in pressure.
[0008] The disadvantages of DA+ electronic control are that it requires professional electronic control calibration, which is costly and complex to maintain.
[0009] Therefore, there is a need for a skid steer loader anti-stalling hydraulic system and a skid steer loader to at least partially solve the above-mentioned technical problems. Summary of the Invention
[0010] This application provides a skid steer loader anti-stalling hydraulic system and a skid steer loader, wherein the hydraulic system can reduce the probability of engine stalling, has a simple structure, and low cost.
[0011] In a first aspect, this application provides a hydraulic system for preventing engine stall in a skid steer loader, the hydraulic system comprising a hydraulic tank, a series pump, a left travel motor, a right travel motor, a shuttle valve, a power valve, a power valve, and a multi-operation valve; The series pumps connected to the hydraulic oil tank are configured to include a first closed-loop piston pump, a second closed-loop piston pump, and an open gear pump for series connection with the drive shaft of the same engine. The two working ports of each of the first closed-loop piston pump and the second closed-loop piston pump are respectively connected to the inlet and outlet ports of the left travel motor and the right travel motor to form their respective hydraulic oil circuits. The inlet and outlet ports of each of the left travel motor and the right travel motor are respectively connected to the inlet port of the shuttle valve. The pressure oil outlet of the shuttle valve is connected to the pressure oil inlet of the power valve, and is used to transmit the highest pressure of the oil pressure of the left travel motor and the right travel motor to the power valve; The oil inlet of the oil source valve is connected to the pressure oil port of the open gear pump, and the pilot oil outlet of the oil source valve is connected to the pilot oil inlet of the power valve, for supplying pilot oil with stable pressure to the power valve. The pilot oil outlet of the power valve is connected to the oil inlet of the multi-operation valve to provide pilot oil to the multi-operation valve. The working ports of the two attachments in the multi-operation valve are respectively connected to the pressure control ports of the first closed-loop piston pump and the second closed-loop piston pump, so as to control the swashplate tilt angle of the corresponding closed-loop piston pump through pilot oil. Specifically, when the oil pressure received at the pressure oil inlet of the power valve is greater than a set value, the power valve reduces the amount of pilot oil supplied to the multi-operation valve.
[0012] According to the hydraulic system of this application, by cooperating with the shuttle valve and power valve, the probability of engine stalling can be reduced, and no power redundancy is left. The cost is low and it is easy to maintain. When the load increases, the multi-operation valve is automatically adjusted to prevent speed fluctuations and vehicle body jerking. There is no power lag when turning at low speed and driving at high speed, forming a pressure protection system for skid steer loaders.
[0013] Optionally, the first closed-loop piston pump includes a first pressure control port a1 and a second pressure control port b1, and the second closed-loop piston pump includes a third pressure control port a2 and a fourth pressure control port b2. The multi-operated valve is constructed as a two-operated valve, including a first attachment link and a second attachment link; The first accessory assembly includes a first working port and a second working port respectively connected to the third pressure control port and the fourth pressure control port; the second accessory assembly includes a third working port and a fourth working port respectively connected to the first pressure control port and the second pressure control port.
[0014] Optionally, the shuttle valve includes an oil inlet A2, an oil inlet B2, an oil inlet C2, an oil inlet D2, and a pressure oil outlet E; The pressure oil outlet E of the shuttle valve is connected to the pressure oil inlet P1 of the power valve.
[0015] Optionally, the oil source valve, the multi-operation valve, and / or the power valve are also connected to the hydraulic oil tank via their respective return oil lines.
[0016] Optionally, the oil source valve is equipped with a solenoid directional valve, which is configured as a two-position three-way solenoid valve. The oil inlet port of the two-position three-way solenoid valve is connected to the oil inlet port P of the oil source valve, the oil outlet port of the two-position three-way solenoid valve is connected to the pilot oil outlet Pr of the oil source valve, and the oil return port of the two-position three-way solenoid valve is connected to the oil return port T of the oil source valve.
[0017] Secondly, this application also provides a skid steer loader, including the hydraulic system described above.
[0018] According to the skid steer loader of this application, because it uses the hydraulic system of the above-mentioned technical solution, it can reduce the probability of engine stalling, has lower cost, and is easy to maintain; and when the load increases, there will be no speed fluctuation or vehicle body jerking, and there will be no power lag when turning at low speed and driving at high speed.
[0019] Additional advantages, objectives, and features of this application will be set forth in part in the description which follows, and will in part become apparent to those skilled in the art upon review of the following description, or may be learned by practice of the application. The objectives and other advantages of this application can be realized and obtained by means of the structures specifically pointed out in the specification and drawings.
[0020] Those skilled in the art will understand that the purposes and advantages that can be achieved with this application are not limited to those specifically described above, and that the above and other purposes that this application can achieve will be more clearly understood from the following detailed description. Attached Figure Description
[0021] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, do not constitute a limitation thereof. The components in the drawings are not drawn to scale but are merely for illustrating the principles of this application. For ease of illustration and description of certain parts of this application, corresponding portions in the drawings may be enlarged, i.e., may appear larger relative to other components in an exemplary device actually manufactured according to this application. In the drawings: Figure 1 This is a schematic diagram of a hydraulic system according to an embodiment of this application.
[0022] Explanation of reference numerals in the attached figures: 100. Hydraulic system; 110. Hydraulic oil tank; 121. First closed-loop piston pump; 122. Second closed-loop piston pump; 123. Open-loop gear pump; 130. Shuttle valve; 140. Power valve; 151. First genus link; 152. Second genus link. Detailed Implementation
[0023] The purposes and functions of this application, as well as the methods for achieving these purposes and functions, will be clarified by referring to exemplary embodiments. However, this application is not limited to the exemplary embodiments disclosed below; it can be implemented in various forms. The specification is merely intended to help those skilled in the art to comprehensively understand the specific details of this application.
[0024] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or combinations thereof.
[0025] Ordinal numbers such as “first” and “second” used in this application are merely identifiers and have no other meaning, such as a specific order. Moreover, for example, the term “first component” does not imply the existence of a “second component”, and the term “second component” does not imply the existence of a “first component”.
[0026] It should be noted that the terms “up,” “down,” “front,” “back,” “left,” “right,” “inner,” “outer,” and similar expressions used in this article are for illustrative purposes only and are not intended to be limiting.
[0027] This application provides a hydraulic system 100 for preventing stalling in skid steer loaders. The hydraulic system 100 can be applied, for example, to skid steer loaders and can solve existing problems such as easy stalling due to overload.
[0028] To address at least one of the aforementioned problems, this application provides a skid steer loader anti-stalling hydraulic system 100. In a preferred embodiment, such as Figure 1 As shown, where Figure 1This is a schematic diagram of a hydraulic system according to an embodiment of this application. The hydraulic system 100 may include a hydraulic oil tank 110, a series pump (or series closed pump), a left travel motor, a right travel motor, a shuttle valve 130, an oil source valve, a power valve 140, and a multi-operation valve.
[0029] Specifically, the hydraulic oil tank 110 is used to store hydraulic oil and can be made using existing technology.
[0030] A series pump connected to a hydraulic oil tank. The series pump can be configured to include a first closed piston pump 121, a second closed piston pump 122, and an open gear pump 123 connected in series with a drive shaft of the same engine (not shown). The two working ports of each of the first closed piston pump 121 and the second closed piston pump 122 can be connected to the inlet and outlet ports of the left travel motor and the right travel motor, respectively, to form their respective hydraulic oil circuits. The inlet and outlet ports of each of the left travel motor and the right travel motor can be connected to their respective inlet ports of the shuttle valve 130.
[0031] The pressure oil outlet of the shuttle valve 130 can be connected to the pressure oil inlet of the power valve 140 to transmit the highest pressure of the oil pressure of the left travel motor and the right travel motor to the power valve 140.
[0032] The oil inlet of the oil source valve can be connected to the pressure port of the open gear pump 123. The pilot oil outlet of the oil source valve can be connected to the pilot oil inlet of the power valve 140 for supplying stable-pressure pilot oil to the power valve 140.
[0033] The pilot oil outlet of the power valve 140 can be connected to the oil inlet of the multi-operation valve to provide pilot oil to the multi-operation valve. The power valve can also be called a constant power control valve or a hydraulic constant power valve.
[0034] The working ports of the two attachments in the multi-operation valve can be connected to the pressure control ports of the first closed-loop piston pump and the second closed-loop piston pump respectively, so as to control the swashplate tilt angle of the corresponding closed-loop piston pump through pilot oil.
[0035] Specifically, when the oil pressure received at the pressure oil inlet of the power valve is greater than the set value, the power valve reduces the amount of pilot oil supplied to the multi-operation valve.
[0036] The hydraulic system 100 according to this application has a simple structure and can reduce the probability of engine stalling; and compared with the prior art, it only requires the addition of a shuttle valve and a power valve, which is inexpensive and easy to maintain; and because the oil pressure information comes from the left and right travel motors and is directly connected to the series pump through the power valve, the oil pressure information accuracy is high and the series pump adjustment speed is fast.
[0037] Reference Figure 1In the illustrated embodiment, the first closed-loop piston pump 121 may include a first pressure control port a1 and a second pressure control port b1. The second closed-loop piston pump 122 may include a third pressure control port a2 and a fourth pressure control port b2.
[0038] A multi-operated valve can be a two-operated valve, including a first accessory link 151 and a second accessory link 152.
[0039] The first attachment 151 may include a first working port 1 and a second working port 2 respectively connected to a third pressure control port and a fourth pressure control port. The second attachment 152 may include a third working port 3 and a fourth working port 4 respectively connected to the first pressure control port and the second pressure control port.
[0040] Furthermore, the shuttle valve 130 may include an oil inlet A2, an oil inlet B2, an oil inlet C2, an oil inlet D2, and a pressure oil outlet E. The pressure oil outlet E of the shuttle valve 130 may be connected to the pressure oil inlet P1 of the power valve 140.
[0041] According to the hydraulic system 100 of this application, the oil source valve, the multi-operation valve and the power valve can also be connected to the hydraulic oil tank via their respective return oil lines.
[0042] In a preferred embodiment, the oil source valve can be equipped with a solenoid directional valve. The solenoid directional valve can be a two-position three-way solenoid valve. The inlet port of the two-position three-way solenoid valve can be connected to the inlet port P of the oil source valve. The outlet port of the two-position three-way solenoid valve can be connected to the pilot oil outlet Pr of the oil source valve. The return port of the two-position three-way solenoid valve can be connected to the return port T of the oil source valve. By switching the energization state (i.e., energized, de-energized) of the two-position three-way solenoid valve, the inlet port can be switched to either its outlet port or return port, thereby enabling the supply of pilot oil to the power valve or the return of oil to the hydraulic tank.
[0043] The working process and principle of the hydraulic system of this application will be introduced below based on the technical solution described above: The engine connects to the tandem pumps, causing them to rotate. The tandem pumps may include a first closed-loop piston pump 121, a second closed-loop piston pump 122, and an open gear pump 123. Each of the two closed-loop piston pumps has two pressure control ports a1 and b1, and a2 and b2, responsible for controlling the swashplate angle of the corresponding closed-loop piston pump. Each closed-loop piston pump's two working ports are connected to a travel motor, forming a hydraulic circuit. For example, the two working ports of the first closed-loop piston pump can be connected to the inlet and outlet of the right travel motor. The two working ports of the second closed-loop piston pump can be connected to the inlet and outlet of the left travel motor.
[0044] Hydraulic oil can be pressurized by the first and second closed-loop piston pumps and then transported through hydraulic pipelines to drive the right and left travel motors respectively. The left and right travel motors can rotate in both directions, and their respective oil inlets and outlets (i.e., the two working oil ports) can be interchanged.
[0045] Each of the left and right travel motors can be equipped with a T-junction at its inlet and outlet. These T-junctions can be connected to the shuttle valve via a hydraulic hose. A total of four hydraulic hoses will connect to the shuttle valve from both travel motors. The inlet and outlet of the left travel motor can be connected to the shuttle valve's inlets A2 and B2. The inlet and outlet of the right travel motor can be connected to the shuttle valve's inlets C2 and D2. Alternatively, they can be connected to inlets A1 and B1, and C1 and D1 respectively.
[0046] The shuttle valve can detect the oil pressure of the left and right travel motors and take the highest pressure, transmitting it through the pressure oil outlet E of the shuttle valve to the pressure oil inlet P1 of the power valve.
[0047] The oil inlet P of the oil source valve can be connected to the pressure port of an open gear pump to receive hydraulic oil supplied by the pump. The return port T of the oil source valve can be connected to a hydraulic oil tank for draining oil. The pilot oil outlet Pr of the oil source valve can be connected to the pilot oil inlet P of the power valve to supply stable-pressure pilot hydraulic oil to the power valve.
[0048] The return port T of the power valve can be connected to the oil tank for draining. The pilot oil outlet A of the power valve can be connected to the inlet P of the multi-operation valve to provide pilot oil to the multi-operation valve.
[0049] The return port T of the multi-operated valve can be connected to the oil tank for draining. A multi-operated valve can also be a two-operated valve. For example, the first and second attachments of a two-operated valve each have two working ports, namely first working port 1 and second working port 2, third working port 3 and fourth working port 4, which can be connected to the pressure control ports a2 and b2, a1 and b1 of the second and first closed-loop piston pumps, respectively. The swashplate angle of the corresponding closed-loop piston pump is controlled by pilot hydraulic oil.
[0050] When the oil pressure received by the power valve's pressure oil inlet P1 from the shuttle valve's pressure oil outlet E exceeds the set oil pressure, for example, greater than 3.5 MPa, the power valve actively reduces the amount of pilot hydraulic oil supplied to the dual-operation valve. When the amount of pilot hydraulic oil supplied through the power valve decreases, even if the dual-operation valve is pushed to its maximum, the hydraulic oil flow will not increase. Therefore, the pilot hydraulic oil supplied to the pressure control ports a1 and b1, a2 and b2 of the first and second closed-loop piston pumps through the dual-operation valve decreases, thereby maintaining or reducing the swashplate angle of the first and second closed-loop piston pumps. The reduced swashplate angle of the first and second closed-loop piston pumps results in less hydraulic oil pumped by them, but the power required by the corresponding closed-loop piston pumps decreases, the engine load decreases, and the travel speed decreases but does not stop, thus preventing engine stalling of the skid steer loader.
[0051] Secondly, this application also provides a skid steer loader, which includes the hydraulic system 100 of the above-described technical solution. Therefore, the skid steer loader according to this application includes all the features and effects of the hydraulic system 100 according to this application, and will not be described further here.
[0052] Other embodiments of this application will be readily conceived and understood by those skilled in the art in conjunction with the description and practice disclosed herein. The descriptions and embodiments are to be considered exemplary only, and the true scope and spirit of this application are defined by the claims.
Claims
1. A hydraulic system for preventing engine stall in a skid steer loader, characterized in that, The hydraulic system includes: Hydraulic oil tank; The series pump connected to the hydraulic oil tank is configured to include a first closed-type piston pump, a second closed-type piston pump, and an open-type gear pump for series connection with the drive shaft of the same engine. The two working ports of the first closed-type piston pump and the second closed-type piston pump are respectively connected to the oil inlet and oil outlet of the left travel motor and the right travel motor. The oil inlet and oil outlet of the left travel motor and the right travel motor are respectively connected to the corresponding oil inlet of the shuttle valve. A shuttle valve, the pressure oil outlet of which is connected to the pressure oil inlet of a power valve, is used to transmit the highest pressure of the oil pressure of the left travel motor and the right travel motor to the power valve; An oil source valve, wherein the oil inlet of the oil source valve is connected to the pressure oil port of the open gear pump, and the pilot oil outlet of the oil source valve is connected to the pilot oil inlet of the power valve; A power valve, wherein the pilot oil outlet of the power valve is connected to the inlet of a multi-operation valve; and A multi-operation valve, wherein the working oil ports of two attachments in the multi-operation valve are respectively connected to the pressure control oil ports of the first closed-loop piston pump and the second closed-loop piston pump, so as to realize the control of the swashplate tilt angle of the corresponding closed-loop piston pump through pilot oil. Specifically, when the oil pressure received at the pressure oil inlet of the power valve is greater than a set value, the power valve reduces the amount of pilot oil supplied to the multi-operation valve.
2. The hydraulic system according to claim 1, characterized in that, The first closed-loop piston pump includes a first pressure control port a1 and a second pressure control port b1, and the second closed-loop piston pump includes a third pressure control port a2 and a fourth pressure control port b2. The multi-operated valve is constructed as a two-operated valve, including a first attachment link and a second attachment link; The first accessory assembly includes a first working port and a second working port respectively connected to the third pressure control port and the fourth pressure control port; the second accessory assembly includes a third working port and a fourth working port respectively connected to the first pressure control port and the second pressure control port.
3. The hydraulic system according to claim 1, characterized in that, The shuttle valve includes an oil inlet A2, an oil inlet B2, an oil inlet C2, an oil inlet D2, and a pressure oil outlet E; The pressure oil outlet E of the shuttle valve is connected to the pressure oil inlet P1 of the power valve.
4. The hydraulic system according to claim 1, characterized in that, The oil source valve, the multi-operation valve, and / or the power valve are also connected to the hydraulic oil tank via their respective return oil lines.
5. The hydraulic system according to claim 1, characterized in that, The oil source valve is equipped with a solenoid directional valve, which is constructed as a two-position three-way solenoid valve. The oil inlet port of the two-position three-way solenoid valve is connected to the oil inlet port P of the oil source valve, the oil outlet port of the two-position three-way solenoid valve is connected to the pilot oil outlet Pr of the oil source valve, and the oil return port of the two-position three-way solenoid valve is connected to the oil return port T of the oil source valve.
6. A skid steer loader, characterized in that, The skid steer loader includes the hydraulic system described in any one of claims 1 to 5.