A loader anti-stall valve structure

Abstract

The utility model belongs to the field of engineering machinery hydraulic system performance improvement, optimization discloses a kind of anti-stall valve structure for loader, including anti-stall valve body, first passage, second passage and the reversing valve valve stem being provided in it are passed through;Still including first shuttle valve, for first pressure oil takeout A1 or first pressure oil takeout A2 high-pressure side pressure oil is introduced to push reversing valve valve stem;Reversing valve valve stem lower end is equipped with the adjusting structure for setting reversing valve opening pressure;Anti-stall valve body is equipped with overflow valve, cut-off slide valve and second shuttle valve for third pressure oil takeout B1 or fourth pressure oil takeout B2 high-pressure side pressure oil is introduced to act on the upper end of cut-off slide valve, cut-off slide valve and overflow valve are always connected.By connecting an anti-stall valve outside the walking pump of the loader, the engine of the loader can meet the power consumption of the working pump and the walking pump during the loading operation, preventing the problem of engine stall caused by insufficient power during operation.

Description

Technical Field

[0001] This utility model relates to an anti-stall valve structure for loaders, belonging to the field of performance improvement and optimization of hydraulic systems for construction machinery. Background Technology

[0002] In actual operation of loaders, such as during loading and transporting materials, the complex and variable working conditions often lead to an imbalance in the loader's power demand. This manifests as a mismatch between the power requirements of the working pump and the travel pump and the engine's power supply, with excessive engine power allocated to the working pump, resulting in a sudden increase in engine load and subsequent engine stalling. With the continuous development of urban construction, small-scale projects, and warehousing and logistics, the demand for compact loaders that can operate in confined spaces and limited access, while offering good economic efficiency, is constantly increasing, placing higher demands on their performance. Existing small loaders, due to their small size and limited installation dimensions, generally use small engines. This size constraint results in lower engine power compared to typical models, making them more prone to stalling during travel and loading operations. This not only reduces the loader's working efficiency but also exacerbates wear and tear on engine and hydraulic system components, increasing maintenance costs and shortening the equipment's lifespan. Therefore, there is an urgent need to design a structure that can ensure that the engine power is distributed to the working pump to meet its loading performance while also meeting the power consumption of the traveling pump, so that the engine does not run at overpower and prevents the engine from stalling due to insufficient power during operation. This plays an important role in improving the performance and stability of the loader and enhancing product competitiveness. Utility Model Content

[0003] The purpose of this invention is to solve the problem of engine stalling caused by the power consumption of the working pump and the travel pump exceeding the engine power during loader operation. By connecting an anti-stalling valve to the travel pump, the engine power can be distributed to the working pump to meet its loading performance while limiting the power of the travel pump to meet its walking and pushing capabilities. This prevents the engine from exceeding its power limit and avoids engine stalling and other problems.

[0004] To achieve the above objectives, this utility model provides an anti-stall valve structure for a loader, including an anti-stall valve body. The anti-stall valve body contains a first channel, a second channel, and a reversing valve stem passing through both. Actuation of the reversing valve stem connects the first and second channels. It also includes a first shuttle valve for introducing high-pressure oil from either the first pressure oil inlet A1 or the first pressure oil inlet A2 to push the reversing valve stem. The lower end of the reversing valve stem has an adjustment structure for setting the opening pressure of the reversing valve. The anti-stall valve body contains an overflow valve and a shut-off valve for limiting the oil pressure in the first channel. The anti-stall valve body also contains a second shuttle valve for introducing high-pressure oil from either the third pressure oil inlet B1 or the fourth pressure oil inlet B2 to act on the upper end of the shut-off valve. The shut-off valve is normally connected to the overflow valve.

[0005] According to this utility model, a stepped groove is provided on the circumferential surface of the middle position of the directional valve stem. When the pressure at the first pressure oil inlet A1 or the first pressure oil inlet A2 at the upper end of the directional valve stem exceeds the set value, the directional valve stem moves down. The first channel and the second channel are both located at the stepped groove of the stepped groove of the directional valve stem. The first channel and the second channel are connected, and the pressure oil at the inlet Y is introduced to the lower end of the cut-off slide valve and connected to the relief valve, so that the pressure at the outlet Y1 does not exceed the pressure limit of the relief valve.

[0006] According to this utility model, the adjusting structure further includes a spring seat fitted around the outer periphery of the directional valve stem, a second spring connected to the spring seat, a valve seat disposed around the outer periphery of the second spring seat, and an adjusting screw inserted into the valve seat and coaxially disposed with the directional valve stem. The spring seat is pressed against the lower end of the directional valve stem by the second spring; the second spring is pressed against the adjusting screw inside the valve seat, and the adjusting screw adjusts the compression of the second spring to set the opening pressure of the directional valve stem.

[0007] According to this utility model, the shut-off slide valve is used to shut off the oil inlet Y from the overflow valve passage. When the shut-off slide valve is activated, the pressure at the oil inlet Y will not be limited by the overflow pressure of the overflow valve.

[0008] According to this utility model, the overflow valve is used to limit the pressure at the oil inlet Y. Its pressure setting value is the minimum pressure to maintain normal walking, so as not to produce phenomena such as weak walking.

[0009] According to this utility model, the anti-galling valve body is provided with a limiting screw plug corresponding to the cut-off slide valve, and the cut-off slide valve is provided with a first spring for pressing the cut-off slide valve onto the limiting screw plug.

[0010] The shut-off slide valve is provided with an oil passage hole, ensuring that the pressure oil in the first channel at one end of the shut-off slide valve remains constantly connected to the oil passage of the relief valve. Compared with the prior art, this utility model has the following beneficial effects:

[0011] The purpose of this invention is to solve the problem of engine stalling caused by the power consumption of the working pump and the travel pump exceeding the engine power during loader operation. By connecting an anti-stalling valve to the loader's travel pump, the engine can meet the power consumption of both the working pump and the travel pump during loading operations, preventing engine stalling due to insufficient power. Attached Figure Description

[0012] Figure 1 A schematic diagram of the external oil passage interface for the anti-gag valve;

[0013] Figure 2 A cross-sectional view of the anti-stalling valve structure (AA section).

[0014] Figure 3 A schematic diagram of the internal structure of the anti-stalling valve;

[0015] Figure 4 Diagram illustrating the working principle of the anti-stalling valve structure;

[0016] Attached reference numerals: Y-oil inlet; Y1-oil outlet; A1-first pressure oil inlet; A2-second pressure oil inlet; B1-third pressure oil inlet; B2-fourth pressure oil inlet; T-drain port; 1-anti-stall valve; 2-limit plug; 3-shut-off spool valve; 4-first spring; 5-first shuttle valve; 6-directional valve stem; 7-first channel; 8-second channel; 9-spring seat; 10-second spring; 11-valve seat; 12-adjusting screw; 13-relief valve; 14-second shuttle valve. Detailed Implementation

[0017] To make this utility model more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0018] like Figures 1 to 3 As shown, the technical solution adopted by this utility model is to provide an anti-stall valve structure for a loader, including an anti-stall valve body 1; a first shuttle valve 5 and a second shuttle valve 14 for introducing high-pressure side pressure oil; a reversing valve stem 6 for connecting the first channel 7 and the second channel 8 arranged in parallel longitudinally, the reversing valve stem 6 being vertically arranged; an adjustment structure for adjusting the shear pressure of the reversing valve stem 6; a cut-off slide valve 3 for connecting or cutting off the second channel 8 and the overflow valve 13, a first spring 4 fitted around the outer periphery of the cut-off slide valve 3, and a limiting screw plug 2 for limiting the axial displacement of the cut-off slide valve 3 to prevent the cut-off slide valve 3 from coming out of the anti-stall valve body 1; and an overflow valve 13 for limiting the pressure of the oil inlet Y, one end of the oil inlet Y being connected to the pilot gear pump of the loader.

[0019] The adjustment structure includes a spring seat 9 fitted around the outer periphery of the directional valve stem 6, a second spring 10 connected to the spring seat 9, a valve seat 11 disposed around the outer periphery of the second spring seat 10, and an adjustment screw 12 inserted into the valve seat 11 and coaxially disposed with the directional valve stem 6.

[0020] The anti-stalling valve body 1 is externally connected to the travel pump and the working pump. The anti-stalling valve body 1 is internally equipped with a first shuttle valve 5, which is used to introduce the pressure oil from the first pressure oil inlet A1 (connected to the front inlet of the travel pump) and the second pressure oil inlet A2 (connected to the working pump) to the upper end face of the reversing valve stem 6. The reversing valve stem 6 is provided with a stepped groove in the middle, which is used to connect the first channel 7 and the second channel 8 when the reversing valve stem 6 is open. The lower end of the reversing valve stem 6 is provided with a spring seat 9, which is pressed against the lower end of the reversing valve stem 6 by a second spring 10. The second spring 10 is provided in the valve seat 11 and is pressed against the adjusting screw 12 in the valve seat 11. The adjusting screw 12 adjusts the compression of the second spring 10 and sets the opening pressure of the reversing valve stem 6.

[0021] The anti-stalling valve body 1 is provided with a shut-off slide valve 3; one end of the shut-off slide valve 3 is provided with a first spring 4 for pressing the shut-off slide valve 3 onto the limit screw plug 2;

[0022] The anti-stalling valve body 1 is equipped with a second shuttle valve 14, which is used to introduce the pressure oil from the third pressure oil inlet B1 (which takes pressure oil from the front pump and the back pump of the travel pump) and the fourth pressure oil inlet B2 (which takes pressure oil from the back pump of the travel pump) to the upper end face of the cut-off slide valve 3; the anti-stalling valve body 1 is equipped with an overflow valve 13 for limiting the oil pressure of the first channel 7.

[0023] The working principle of this utility model is as follows: the first pressure oil inlet A1 is connected to the oil outlet of the working pump, the second pressure oil inlet A2 is connected to the oil outlet of the forward end of the travel pump, and the oil outlets of the forward and rear pumps of the travel pump can be connected to either one; the oil inlet Y is connected to the oil outlet of the pilot pump, the oil outlet Y1 is connected to the oil inlet of the pilot handle, the oil inlet Y and the oil outlet Y1 are normally connected, the third pressure oil inlet B1 is connected to the front pump rear exit oil outlet of the travel pump, the fourth pressure oil inlet B2 is connected to the rear pump rear exit oil outlet of the travel pump, and the oil drain T is connected to the oil tank for oil draining.

[0024] When the loader is performing a shoveling operation, the working pump outputs high pressure to drive the boom and bucket to shovel, and the travel pump outputs a large flow rate to the motor to push the shovel. When the shoveling encounters resistance, the working pump's pressure increases instantaneously, and the pressure at the first pressure oil tap A1 is greater than that at the second pressure oil tap A2. The pressure at the first pressure oil tap A1 passes through the first shuttle valve and acts on the upper end face of the directional valve stem, overcoming the second spring force and pushing the directional valve stem downward. Both the first and second channels are located at the stepped groove of the directional valve stem, that is, the stepped groove of the directional valve stem connects the first and second channels. The pressure oil at the inlet Y flows through the first channel to one end of the shut-off spool valve, which is controlled by the first spring. When the plug is tightened to the end face of the limit screw, its lower end small hole is normally connected to the relief valve. At this time, the pressure oil at the inlet Y flows through the lower end small hole of the cut-off slide valve to the relief valve. The relief valve limits the pressure at the inlet Y. The inlet Y and the outlet Y1 are normally connected, that is, the pressure is the same. At this time, the outlet Y1 outputs the pressure limited by the relief valve to the pilot handle. When the operator moves the pilot handle at a constant angle, the pressure on the pilot handle decreases, which leads to a decrease in the pressure output to the hydraulic control valve of the travel pump. The valve stem stroke of the hydraulic control valve becomes shorter, which reduces the opening of the oil passage of the servo plunger output to the travel pump. The pressure oil flowing through the servo plunger acts on the force value of the servo plunger, the stroke of the servo plunger decreases, the displacement of the travel pump decreases, and the power consumption required by the travel pump decreases.

[0025] When the loader executes the reverse command, the third pressure oil inlet B1 and the fourth pressure oil inlet B2 simultaneously connect to the reverse pressure of the travel pump. The pressure oil passes through the second shuttle valve to the upper end of the cut-off slide valve, overcoming the force of the first spring and the pressure at the inlet Y acting on the lower end of the cut-off slide valve. The cut-off slide valve moves downward, closing the small orifice at the lower end. The pressure at the inlet Y is no longer controlled by the overflow valve. At this time, the pressure at the outlet Y1 is the pilot pressure, the servo plunger of the travel pump outputs its maximum stroke, and the travel pump outputs its maximum displacement. The reverse speed of the loader is unaffected. This solves the problem of unbalanced power demand in the loader, which leads to a sudden increase in engine load and subsequently stalling.

[0026] The above description is merely a preferred embodiment of this utility model and is not intended to limit this utility model in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from this utility model, and these improvements and additions should also be considered within the protection scope of this utility model. Any modifications, alterations, and equivalent changes made by those skilled in the art without departing from the spirit and scope of this utility model using the disclosed technical content are equivalent embodiments of this utility model. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of this utility model are still within the scope of the technical solution of this utility model.

Claims

1. A load-holding valve structure for a loader characterized by comprising: The device includes an anti-stall valve body, which contains a first channel, a second channel, and a directional valve stem passing through both. Actuation of the directional valve stem connects the first and second channels. It also includes a first shuttle valve for introducing high-pressure oil from either the first pressure oil inlet A1 or A2 to push the directional valve stem. The lower end of the directional valve stem has an adjustment structure for setting the opening pressure of the directional valve. The anti-stall valve body contains an overflow valve and a shut-off spool valve for limiting the oil pressure in the first channel. Furthermore, the anti-stall valve body also contains a second shuttle valve for introducing high-pressure oil from either the third pressure oil inlet B1 or the fourth pressure oil inlet B2 to act on the upper end of the shut-off spool valve. The shut-off spool valve is normally connected to the overflow valve.

2. The anti-stall valve structure for a loader as claimed in claim 1, wherein The directional valve stem has a stepped groove on its circumferential surface at the middle position. When the pressure at the first pressure oil inlet A1 or the first pressure oil inlet A2 at the upper end of the directional valve stem exceeds the set value, the directional valve stem moves down. The first channel and the second channel are both located at the stepped groove of the stepped groove of the directional valve stem. The first channel and the second channel are connected, introducing the pressure oil at the inlet Y into the lower end of the shut-off slide valve and connecting it with the relief valve, so that the pressure at the outlet Y1 does not exceed the pressure limit of the relief valve.

3. The anti-stall valve structure for a loader as claimed in claim 1, wherein The adjustment structure includes a spring seat fitted around the outer periphery of the directional valve stem, a second spring connected to the spring seat, a valve seat disposed around the outer periphery of the second spring seat, and an adjusting screw inserted into the valve seat and coaxially disposed with the directional valve stem. The spring seat is pressed against the lower end of the directional valve stem by the second spring; the second spring is pressed against the adjusting screw inside the valve seat, and the adjusting screw adjusts the compression of the second spring to set the opening pressure of the directional valve stem.

4. The anti-stall valve structure for a loader defined in Claim 1, wherein The shut-off slide valve is used to cut off the oil inlet Y from the overflow valve passage. When the shut-off slide valve is activated, the pressure at the oil inlet Y will not be limited by the overflow pressure of the overflow valve.

5. The load holder anti-stall valve structure of claim 1 wherein, The overflow valve is used to limit the pressure at the oil inlet Y. Its pressure setting value is the minimum pressure to maintain normal walking and will not cause phenomena such as weak walking.

6. The anti-stall valve structure for a loader defined in claim 1, wherein The anti-stalling valve body is provided with a limit screw plug corresponding to the cut-off slide valve, and the cut-off slide valve is provided with a first spring for pressing the cut-off slide valve onto the limit screw plug.

7. The anti-stall valve structure for a loader according to claim 1 or 6, characterized in that The shut-off slide valve is provided with an oil passage hole, so that the pressure oil in the first channel at one end of the shut-off slide valve is always connected to the oil passage of the relief valve.

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