Loader gearbox shift buffer multifunctional speed control valve and control method thereof

Abstract

The present invention discloses a multifunctional speed-shifting control valve for a loader gearbox shifting buffer and a control method thereof. The invention belongs to the technical field of speed-shifting control valves for loaders, and the speed-shifting control valve for loaders can solve the technical problem of shifting shock. The invention comprises a valve body, wherein a braking device is arranged in the valve body, a pressure-reducing balancing device is installed in the valve body above the braking device, a secondary energy storage buffer device is installed on the valve body located on the left side of the braking device, a speed-shifting device is installed on the valve body located below the secondary energy storage buffer device, a first main oil circuit connected to the pressure-reducing balancing device and the braking device is arranged in the valve body, a second main oil circuit connected to the braking device and the secondary energy storage buffer device is arranged in the valve body located below the first main oil circuit, the second main oil circuit is connected to the balancing oil circuit, and a working oil circuit connected to the speed-shifting device and the secondary energy storage buffer device is arranged in the valve body located below the second main oil circuit.

Description

Technical Field

[0001] The invention relates to the technical field of loader speed change control valves, and in particular to a loader gearbox shift buffer multifunctional speed change control valve and a control method thereof. Background Art

[0002] Most of the ZL40 / 50 loader gearboxes currently in widespread use in China use fixed-axis hydraulic shift and speed control valves. This type of gearbox and speed control valve were introduced from abroad in the 1960s and 1970s. However, due to different operating environments at home and abroad, different operating standards during operation, and different operating habits of operators, the technical problem of large shift shock during loader operation has arisen. Over the years, loader manufacturers, gearbox manufacturers, and speed control valve manufacturers have made technical improvements to the speed control valve many times, but none of them have completely solved the technical problem of shift shock.

[0003] The clutch engagement rule of the ZL40 / 50 gearbox in the prior art is that it is initially engaged when the oil pressure rises to 0.8MPa, engages when the oil pressure rises to 1.0MPa, and is tightened when the oil pressure rises to 1.4MPa. The original pressure increase curve causes the gearbox clutch to engage too quickly because the time it takes for the oil pressure to rise to 0.8MPa and 1.0MP is short, thus causing gear shift shock. Summary of the invention

[0004] The present invention aims to solve the problem of large gear shifting shock in the existing loader speed control valve, and provides a loader gearbox gear shifting buffer multifunctional speed control valve and a control method thereof, which can add a secondary energy storage buffer device while not changing the docking size of the installation oil port of the original speed control valve, solve the technical problem of gear shifting shock, and optimize the combination of various structures of the speed control valve to meet the differentiated needs of loader host manufacturers for gearboxes and speed control valves.

[0005] The above technical problems are solved by the following technical solutions:

[0006] A multifunctional speed-changing control valve for gearbox shifting and buffering of a loader comprises a valve body, wherein a braking device is arranged in the valve body, a pressure reducing and balancing device is installed in the valve body above the braking device, a secondary energy storage and buffering device is installed on the valve body located on the left side of the braking device, and a speed-changing and shifting device is installed on the valve body located below the secondary energy storage and buffering device, a first main oil circuit connected with the pressure reducing and balancing device and the braking device is arranged in the valve body, a second main oil circuit connected with the braking device and the secondary energy storage and buffering device is arranged in the valve body below the first main oil circuit, the second main oil circuit is communicated with the balancing oil circuit, and a working oil circuit connected with the speed-changing and shifting device and the secondary energy storage and buffering device is arranged in the valve body below the second main oil circuit.

[0007] Preferably, the pressure reducing balancing device includes a balancing valve chamber connected to the left side of the pressure reducing valve chamber, a pressure reducing valve stem with a pressurizing hole is installed in the pressure reducing valve chamber, the pressure reducing valve stem is tightly connected to the right end of the balancing slider through a pressure reducing spring, a pressure regulating plate is provided between the pressure reducing valve stem and the pressure reducing spring, the balancing slider is tightly connected in the balancing valve chamber through a balancing spring, and the balancing valve chamber is connected to both the balancing oil circuit and the first main oil circuit.

[0008] Preferably, the secondary energy storage buffer device includes an energy storage buffer valve hole with a balancing valve stem, the energy storage buffer valve hole is connected to the second main oil circuit, a balancing valve stem boosting chamber is provided at the bottom of the balancing valve stem, the balancing valve stem boosting chamber is connected to the working oil circuit, one end of the balancing valve stem is sleeved on the energy storage spring, the energy storage spring is sleeved on the energy storage valve sleeve, a cover plate with a cover plate paper pad is installed on the outer side of the balancing valve stem, the cover plate is fixedly connected to the valve body by cover plate screws, an energy storage chamber and an energy storage boosting oil circuit are provided between the cover plate and the energy storage valve sleeve, an energy storage throttle nozzle which is connected to the energy storage chamber control is provided at the left end of the energy storage boosting oil circuit, a one-way valve oil circuit and an energy storage oil return pipe which are connected to the energy storage throttle nozzle are provided on the energy storage boosting oil circuit at the right end of the energy storage throttle nozzle in sequence, and an oil return chamber is provided on the valve body between the one-way valve oil circuit and the energy storage oil return pipe.

[0009] Preferably, a guide needle valve throttle nozzle assembly is installed on the valve body located on the right side of the balancing oil circuit, and the guide needle valve throttle nozzle assembly includes a one-way valve oil circuit arranged at the bottom end of the valve body and connected to the balancing valve chamber, a one-way valve with a one-way valve baffle is installed at the inlet of the one-way valve oil circuit, and a guide needle valve throttle nozzle is provided on the valve body located above the one-way valve, and the guide needle valve throttle nozzle is connected to the balancing oil circuit through a throttle hole, and a guide needle valve is provided in the throttle hole.

[0010] Preferably, a second one-way valve is installed on the valve body located on the left side of the guide needle valve, and the second one-way valve includes a control ball installed on the one-way valve oil circuit, a second one-way valve baffle is installed on the right end of the control ball, and a one-way valve transition oil circuit connected to the energy storage and boosting oil circuit is provided on the valve body located below the one-way valve oil circuit.

[0011] Preferably, the braking device includes a brake valve chamber connected to the first main oil circuit, the brake valve chamber is provided with a connection to the second main oil circuit and the balance oil circuit, a brake valve stem with a pneumatic spring is installed in the brake valve chamber, and a closed main oil circuit normally open brake assembly is provided on the valve body at the left end of the brake valve stem, the closed main oil circuit normally open brake assembly includes a brake piston movably connected in the brake valve, the brake piston is drivingly connected to the left end of the brake push rod, and the left end of the brake piston is provided with a drive interface.

[0012] Preferably, the braking device includes a brake valve chamber connected to the first main oil circuit, the brake valve chamber is provided with a connection to the second main oil circuit and the balance oil circuit, a brake valve rod with a pneumatic spring is installed in the brake valve chamber, and the valve body at the left end of the brake valve rod is provided with an air pressure-driven air valve body main oil circuit normally open brake assembly, the air pressure-driven air valve body main oil circuit normally open brake assembly includes an air valve body installed at the left end of the air valve seat, a brake valve joint bolt is installed at the right end of the air valve seat, an air valve stem with an air valve spring is installed in the air valve body, the air valve stem drives a cylindrical plug connected to the brake valve joint bolt, the brake valve joint bolt is fixedly installed on the air valve seat by a locking nut, the air valve stem is sealed connected to the air valve body by a Y-shaped sealing ring, and the cylindrical plug is sealed connected to the brake valve joint bolt by a cylindrical plug sealing ring.

[0013] Preferably, the braking device includes a brake valve chamber connected to the first main oil circuit, the brake valve chamber is provided with a connection connected to the second main oil circuit and the balance oil circuit, a brake valve rod with a pneumatic spring is installed in the brake valve chamber, and the valve body at the left end of the brake valve rod is provided with a pneumatically driven main oil circuit normally closed power cut-off assembly, the pneumatically driven main oil circuit normally closed power cut-off assembly includes an intake valve body and a joint body respectively installed at the left and right ends of the intake valve seat, a power cut-off valve with a second pneumatic joint is installed at the left end of the intake valve body, an intake valve stem is provided in the intake valve body, the intake valve stem is pressed and connected to the left side of the intake valve seat by a power cut-off spring, the right end of the intake valve stem is driven and connected to the cylindrical plug, and a first pneumatic joint connected to the intake valve body is provided at the bottom of the intake valve seat.

[0014] Preferably, the speed shifting device includes an operating valve stem installed in the operating valve cavity, a shift rod fixedly connected to the right end of the operating valve stem is provided, a signal block is provided at the end of the shift rod, an embedded dust cover is provided on the left side of the operating valve stem, and limit steel balls with limit springs are installed on the upper and lower sides of the shift rod, the limit steel balls are pressed and contacted on the shift rod, a shift screw plug for limiting is provided on the outer side of the limit steel ball located below the shift rod, and a limit signal screw plug matching the signal block is provided on the valve body located on the right side of the signal block.

[0015] Preferably, the speed shifting device includes an operating valve stem installed in the operating valve cavity, a shift rod fixedly connected to the right end of the operating valve stem is provided, a signal block is provided at the end of the shift rod, an external snap-on dust cover is provided on the left side of the operating valve stem, the external snap-on dust cover includes a cover shell installed on the right side of the valve body, a skeleton oil seal sealingly connected to the valve body is provided in the cover shell, the skeleton oil seal is sealingly connected to the valve body through a combined sealing ring, a limit retaining ring is provided on the left side of the skeleton oil seal, and a limit signal screw plug matching the signal block is provided on the valve body located on the right side of the signal block.

[0016] Preferably, a main oil circuit overload protection component is provided at the bottom end of the valve body and is controllably connected to the first main oil circuit. The main oil circuit overload protection component includes a safety valve ball. The safety valve ball is compressed and connected to the upper end of the safety valve cavity by a safety valve spring. A safety valve bolt with a safety valve sealing ring is installed at the bottom end of the safety valve cavity.

[0017] A control method for a multifunctional speed control valve for a gear shift buffer of a loader gearbox, the method comprising the following steps: 1. A pressure reducing valve stem is provided with a pressure increasing hole and connected to a pressure increasing chamber. When the oil pump inputs high-pressure oil, the oil enters the pressure increasing chamber from the pressure increasing hole and forms a high pressure between the pressure reducing balancing device and the pressure reducing balancing device, thereby compressing the pressure reducing valve stem and causing the pressure reducing spring to move inward, thereby realizing the oil return pressure reducing of the pressure reducing balancing device. According to the pressure setting of the pressure reducing spring, the main pressure of the valve body is set between 1.1 and 1.6 MPa. 2. When the valve body is pressurized, the one-way valve is automatically closed, and oil is introduced through the throttle hole, so that the high pressure is formed in the pressure reducing balancing device and causes the balancing slider to move right, and the compressing balancing spring and the pressure reducing spring maintain pressure balance, thereby adjusting the main oil pressure within a set pressure range. When the valve body is depressurized, the one-way valve opens rapidly, the high pressure of the pressure reducing balancing device disappears, and the balancing slider moves leftward. Since the pressure of the balancing spring and the pressure reducing spring loses balance, the high pressure rapidly pushes the pressure reducing valve stem to move leftward, thereby reducing the oil inlet and expanding the pressure reducing oil return port, and simultaneously connecting the quick relief valve on the right. The oil returns to the oil return cavity through the quick return port, so that the main oil pressure drops rapidly from 1.1~1.6MPa to below 0.5MPa, and then quickly returns to the set main pressure after the gear is switched; Third: When the valve body shifts gears, the working oil circuit loses pressure, the pressure in the boosting cavity of the balancing valve stem disappears, and the pressure in the energy storage boosting oil circuit disappears, the second one-way valve opens, the pressure in the energy storage cavity disappears, and the balancing valve stem and the energy storage valve sleeve are separated by the energy storage spring, and each moves to the limit position in the opposite direction. At this time, the balancing valve stem will store energy. The oil inlet on the buffer valve hole is blocked, and the hydraulic oil in the secondary energy storage buffer device is emptied from the buffer oil return port; when the valve body shifts, the oil pressure of the first main oil circuit, the second main oil circuit and the working oil circuit rises, and the hydraulic oil enters the balance valve stem booster chamber through the control oil circuit of the balance valve stem booster chamber; the oil pressure of the energy storage booster oil circuit rises at the same time, closing the one-way valve and entering the energy storage chamber through the dredging needle valve throttle nozzle, synchronously pushing the energy storage valve sleeve and the balance valve stem to move in opposite directions, compressing the energy storage spring, at about 0.8~1.Slowly open the working oil inlet of the secondary energy storage buffer device within 6S; Four: A signal block is set at the tail of the operating valve stem. When the operating valve stem is positioned in neutral, the signal block is aligned with the contact electronic signal switch located above the valve body, and the electronic signal switch is turned on to transmit the neutral signal to the host. When the neutral gear is switched to the reverse gear or the forward gear, the electronic signal switch is closed; hydraulic signal ports are set at the corresponding positions above the gear lever of the valve body, and hydraulic signal switches are installed. When the operating valve stem is switched to the corresponding gear, the hydraulic signal switch is turned on to transmit the correct gear real-time signal to the host, so that the operator can grasp the gear information at any time; Five: When the loader needs to stop during operation, open the drive The air / hydraulic pressure pushes the brake piston, brake push rod and brake valve stem, compresses the pneumatic spring, and causes the brake valve stem to cut off the first main oil circuit and the second main oil circuit and release the pressure through the brake valve stem to the oil return port of the valve body; after the air / hydraulic pressure is removed, the pneumatic spring pushes the brake valve stem back to reset, the main oil circuit is connected to restore the main pressure, and the loader resumes working state; Six: When the power cut-off valve is closed, the power cut-off spring installed in the intake valve body is compressed to push the air valve stem and the cylindrical plug against the brake valve stem to move toward the inner axis, cutting off the working oil circuit and connecting the working oil circuit with the oil return chamber. At this time, the oil pressure of the working oil circuit is 0MPa; in this state, the loader can be started even when the valve body is in gear. , since the oil pressure of the working oil circuit is cut off, the loader cannot move, which improves the reliability of safe operation; when the loader is not working or in the working interval under the motor starting state, the power cut-off valve is not opened, and the main oil pressure of the valve body is 0MPa; when the power cut-off valve needs to be opened, a gas pressure of ≥0.45MPa enters between the intake valve seat and the intake valve stem from the air inlet of the first pneumatic joint of the air valve seat to form a pressure chamber, and the residual gas in the intake valve body is discharged from the second pneumatic joint, the power cut-off spring is compressed, and the intake valve stem moves outward. At this time, the brake valve stem is reset by the action of the pneumatic spring, and after closing the return oil, the first main oil circuit and the second main oil circuit are connected to restore the working state. The loader can move in this state; when the main oil circuit needs to be cut off, the air pressure is removed from the first pneumatic joint of the intake valve seat, and an emergency air pressure of ≥0.45MPa is introduced from the second pneumatic joint interface. Under the thrust of the power cut-off spring, the intake valve stem, the cylindrical plug, and the brake valve stem are pushed inward axially to cut off the first main oil circuit and the second main oil circuit, so that the second main oil circuit is connected to the return oil chamber. At this time, the working oil pressure is reduced to 0MPa; Seven: The safety valve chamber is connected to the return oil chamber of the valve body. The safety opening pressure set by the safety valve spring is 1.5 times the main oil pressure. When the valve body pressure relief system fails and the main oil pressure is instantly too high, the safety valve ball moves down to open and relieve pressure to ensure the safe use of the valve body.

[0018] The present invention can achieve the following effects:

[0019] The present invention provides a multifunctional speed control valve for gear shifting buffer of a loader gearbox and a control method thereof, which can add a secondary energy storage buffer device while not changing the docking size of the installation oil port of the original speed control valve, solve the technical problem of gear shifting impact, and optimize the combination of various structures of the speed control valve to meet the differentiated needs of loader host manufacturers for gearboxes and speed control valves. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The figure is a schematic diagram of the overall structure of an embodiment of the present invention.

[0021] Figure 2 for Figure 1 A structural cross-sectional view of .

[0022] Figure 3 for Figure 1 Oil circuit distribution diagram.

[0023] Figure 4 It is a structural schematic diagram of a drainage needle valve throttle nozzle assembly in an embodiment of the present invention.

[0024] Figure 5 Schematic diagram of the oil circuit distribution of the secondary energy storage buffer device in an embodiment of the present invention.

[0025] Figure 6 Schematic diagram of the structure of the second one-way valve in an embodiment of the present invention.

[0026] Figure 7 Schematic diagram of the structure of a speed shifting device in an embodiment of the present invention.

[0027] Figure 8 Schematic diagram of a structure of a braking device in an embodiment of the present invention.

[0028] Fig. 9 Schematic diagram of a structure of a braking device in an embodiment of the present invention.

[0029] Fig.10 Schematic diagram of the structure of the main oil circuit overload protection component in an embodiment of the present invention.

[0030] In the figure: valve body 1, pressure reducing balancing device 2, braking device 3, secondary energy storage buffer device 4, speed shifting device 5, dredging needle valve throttle nozzle assembly 6, second one-way valve 7, first main oil circuit 8, second main oil circuit 9, balancing oil circuit 10, working oil circuit 11, balancing slider 21, balancing spring 22, pressure reducing spring 23, pressure regulating plate 24, pressure reducing valve stem 25, pressure reducing valve cavity 26, boosting hole 27, balancing valve cavity 28, energy storage boosting oil circuit 40, balancing valve stem boosting cavity 41, balancing valve stem 42, energy storage buffer valve hole 43, energy storage valve sleeve 44 , energy storage spring 45, energy storage chamber 46, cover plate 47, cover plate paper pad 48, cover plate screw 49, energy storage throttle nozzle 401, energy storage oil return pipe 402, oil return chamber 403, dredging needle valve throttle nozzle 61, throttle hole 62, dredging needle valve 63, one-way valve baffle 64, one-way valve 65, one-way valve oil circuit 66, second one-way valve baffle 71, control ball 72, one-way valve transition oil circuit 73, pneumatic spring 31, brake valve rod 32, brake valve chamber 33, closed main oil circuit normally open brake assembly 34, brake valve 341, drive interface 342, brake active Plug 343, brake push rod 344, air pressure driven air valve body main oil circuit normally open brake assembly 35, Y-type sealing ring 351, air valve seat 352, air valve stem 353, cylindrical plug sealing ring 354, cylindrical plug 355, air valve body 356, air valve spring 357, locking nut 358, brake valve joint bolt 359, air pressure driven main oil circuit normally closed power cut-off assembly 36, power cut-off valve 361, power cut-off spring 362, intake valve body 363, intake valve stem 364, intake valve seat 365, joint body 366, cylindrical plug 367, the first Second pneumatic joint 368, first pneumatic joint 369, operating valve stem 51, operating valve chamber 52, limit spring 53, limit steel ball 54, shift screw plug 55, shift rod 56, signal block 57, limit signal screw plug 58, embedded dust cover 59, external buckle dust cover 50, cover shell 501, combined sealing ring 502, limit retaining ring 503, skeleton oil seal 504, main oil circuit overload protection assembly 13, safety valve ball 131, safety valve chamber 132, safety valve spring 133, safety valve sealing ring 134, safety valve bolt 135. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0032] Example 1, a loader gearbox shift buffer multifunctional speed control valve, see Figure 1-3As shown, it includes a valve body 1, in which a braking device 3 is provided, a pressure reducing balancing device 2 is installed in the valve body 1 above the braking device 3, a secondary energy storage buffer device 4 is installed on the valve body 1 on the left side of the braking device 3, and a speed shifting device 5 is installed on the valve body 1 below the secondary energy storage buffer device 4, a first main oil circuit 8 connected with the pressure reducing balancing device 2 and the braking device 3 is provided in the valve body 1, a second main oil circuit 9 connected with the braking device 3 and the secondary energy storage buffer device 4 is provided in the valve body 1 below the first main oil circuit 8, the second main oil circuit 9 is connected with the balancing oil circuit 10, and a working oil circuit 11 connected with the speed shifting device 5 and the secondary energy storage buffer device 4 is provided in the valve body 1 below the second main oil circuit 9.

[0033] See also Figure 2-3As shown, the pressure reducing balancing device 2 includes a balancing valve chamber 28 connected to the left side of the pressure reducing valve chamber 26, a pressure reducing valve stem 25 with a pressurizing hole 27 is installed in the pressure reducing valve chamber 26, the pressure reducing valve stem 25 is tightly connected to the right end of the balancing slider 21 through a pressure reducing spring 23, a pressure regulating plate 24 is provided between the pressure reducing valve stem 25 and the pressure reducing spring 23, the balancing slider 21 is tightly connected in the balancing valve chamber 28 through a balancing spring 22, and the balancing valve chamber 28 is connected to both the balancing oil circuit 10 and the first main oil circuit 8. The secondary energy storage buffer device 4 includes an energy storage buffer valve hole 43 with a balancing valve stem 42, and the energy storage buffer valve hole 43 is connected to the second main oil circuit 9. A balancing valve stem boosting chamber 41 is provided at the bottom of the balancing valve stem 42, and the balancing valve stem boosting chamber 41 is connected to the working oil circuit 11. One end of the balancing valve stem 42 is sleeved on an energy storage spring 45, and an energy storage valve sleeve 44 is sleeved on the energy storage spring 45. A cover plate 47 with a cover plate paper pad 48 is installed on the outer side of the balancing valve stem 42. The cover plate 47 is fixedly connected to the valve body 1 by a cover screw 49, and an energy storage chamber 46 and an energy storage boost oil circuit 40 are provided between the cover plate 47 and the energy storage valve sleeve 44, and an energy storage throttle nozzle 401 which is controlled and connected to the energy storage chamber 46 is provided at the left end of the energy storage boost oil circuit 40, and a one-way valve oil circuit 66 and an energy storage oil return pipe 402 which are connected thereto are provided in sequence on the energy storage boost oil circuit 40 located at the right end of the energy storage throttle nozzle 401, and an oil return chamber 403 is provided on the valve body 1 between the one-way valve oil circuit 66 and the energy storage oil return pipe 402. The braking device 3 includes a brake valve chamber 33 connected to the first main oil circuit 8, and the brake valve chamber 33 is connected to the second main oil circuit 9 and the balance oil circuit 10. A brake valve rod 32 with a pneumatic spring 31 is installed in the brake valve chamber 33, and a closed main oil circuit normally open brake assembly 34 is provided on the valve body 1 at the left end of the brake valve rod 32. The closed main oil circuit normally open brake assembly 34 includes a brake piston 343 movably connected in the brake valve 341, and the brake piston 343 is drivingly connected to the left end of the brake push rod 344. The left end of the brake piston 343 is provided with a driving interface 342. The speed shifting device 5 includes an operating valve stem 51 installed in an operating valve cavity 52, a shift rod 56 fixedly connected to the right end of the operating valve stem 51 is provided, a signal block 57 is provided at the end of the shift rod 56, an embedded dust cover 59 is provided on the left side of the operating valve stem 51, and limiting steel balls 54 with limiting springs 53 are installed on the upper and lower sides of the shift rod 56, and the limiting steel balls 54 are pressed and contacted on the shift rod 56, and a shift plug screw 55 for limiting is provided on the outer side of the limiting steel ball 54 located below the shift rod 56, and a limiting signal plug screw 58 matched with the signal block 57 is provided on the valve body 1 located on the right side of the signal block 57.

[0034] See also Figure 4As shown, a dredging needle valve throttle nozzle assembly 6 is installed on the valve body 1 located on the right side of the balancing oil circuit 10, and the dredging needle valve throttle nozzle assembly 6 includes a one-way valve oil circuit 66 arranged at the bottom end of the valve body 1 and connected to the balancing valve chamber 28, a one-way valve 65 with a one-way valve baffle 64 is installed at the inlet of the one-way valve oil circuit 66, and a dredging needle valve throttle nozzle 61 is provided on the valve body 1 located above the one-way valve 65, and the dredging needle valve throttle nozzle 61 is connected to the balancing oil circuit 10 through a throttle hole 62, and a dredging needle valve 63 is provided in the throttle hole 62.

[0035] See also Figure 6 As shown, a second one-way valve 7 is installed on the valve body 1 located on the left side of the guide needle valve 63, and the second one-way valve 7 includes a control ball 72 installed on the one-way valve oil circuit 66. A second one-way valve baffle 71 is installed on the right end of the control ball 72. A one-way valve transition oil circuit 73 connected to the energy storage and boosting oil circuit 40 is provided on the valve body 1 located below the one-way valve oil circuit 66.

[0036] See also Fig.10 As shown, a main oil circuit overload protection component 13 which is controllably connected to the first main oil circuit 8 is provided at the bottom end of the valve body 1. The main oil circuit overload protection component 13 includes a safety valve ball 131. The safety valve ball 131 is compressed and connected to the upper end of a safety valve chamber 132 through a safety valve spring 133. A safety valve bolt 135 with a safety valve sealing ring 134 is installed at the bottom end of the safety valve chamber 132.

[0037] Embodiment 2 is different from Embodiment 1 in that, see Figure 7 As shown, the speed shifting device 5 includes an operating valve stem 51 installed in an operating valve cavity 52, a shift rod 56 fixedly connected to the right end of the operating valve stem 51 is provided, a signal block 57 is provided at the end of the shift rod 56, an embedded dust cover 59 is provided on the left side of the operating valve stem 51, and limiting steel balls 54 with limiting springs 53 are installed on the upper and lower sides of the shift rod 56, and the limiting steel balls 54 are pressed and contacted on the shift rod 56, and a shift screw plug 55 for limiting is provided on the outer side of the limiting steel ball 54 located below the shift rod 56, and a limiting signal screw plug 58 matched with the signal block 57 is provided on the valve body 1 located on the right side of the signal block 57.

[0038] Embodiment 3 is different from Embodiment 1 in that, see Figure 8As shown, the brake device 3 includes a brake valve chamber 33 connected to the first main oil circuit 8, and the brake valve chamber 33 is connected to the second main oil circuit 9 and the balance oil circuit 10. A brake valve rod 32 with a pneumatic spring 31 is installed in the brake valve chamber 33, and a pneumatically driven air valve body main oil circuit normally open brake assembly 35 is provided on the valve body 1 at the left end of the brake valve rod 32. The pneumatically driven air valve body main oil circuit normally open brake assembly 35 includes an air valve body 356 installed at the left end of the air valve seat 352, and the air valve seat 352 is installed at the right end. A brake valve joint bolt 359 is installed, and an air valve stem 353 with an air valve spring 357 is installed in the air valve body 356. The air valve stem 353 drives a cylindrical plug 355 connected to the brake valve joint bolt 359. The brake valve joint bolt 359 is fixedly installed on the air valve seat 352 through a locking nut 358. The air valve stem 353 is sealed connected to the air valve body 356 through a Y-shaped sealing ring 351, and the cylindrical plug 355 is sealed connected to the brake valve joint bolt 359 through a cylindrical plug sealing ring 354.

[0039] Embodiment 4 is different from Embodiment 1 in that, see Fig. 9 As shown, the brake device 3 includes a brake valve chamber 33 connected to the first main oil circuit 8, the brake valve chamber 33 is connected to the second main oil circuit 9 and the balance oil circuit 10, a brake valve rod 32 with a pneumatic spring 31 is installed in the brake valve chamber 33, and a pneumatically driven main oil circuit normally closed power cut-off component 36 is provided on the valve body 1 at the left end of the brake valve rod 32, and the pneumatically driven main oil circuit normally closed power cut-off component 36 includes air intake valves 365 respectively installed at the left and right ends of the air intake valve seat 365. The valve body 363 and the connector body 366, the left end of the intake valve body 363 is equipped with a power cut-off valve 361 with a second pneumatic connector 368, the intake valve body 363 is provided with an intake valve stem 364, the intake valve stem 364 is pressed and connected to the left side of the intake valve seat 365 by a power cut-off spring 362, the right end of the intake valve stem 364 is driven and connected to the cylindrical plug 367, and the bottom of the intake valve seat 365 is provided with a first pneumatic connector 369 which is connected to the intake valve body 363.

[0040] A control method for a multifunctional speed control valve for a gear shift buffer of a loader transmission, the method comprising the following steps: 1. A pressure relief valve stem 25 is provided with a pressure boost hole 27 and is connected to a pressure boost chamber 28. When the oil pump inputs high-pressure oil, it enters the pressure boost chamber 28 from the pressure boost hole 27 and forms a high pressure between the pressure relief balance device 2, which pushes the pressure relief valve stem 25 to compress and causes the pressure relief spring 23 to move inward, thereby realizing the oil return pressure relief of the pressure relief balance device 2. According to the pressure setting of the pressure relief spring 23, the main pressure of the valve body 1 is set between 1.1 and 1.6 MPa; 2. When the pressure of the valve body 1 is increased, the one-way The valve 65 closes automatically, and oil flows in through the throttle hole 62, forming a high pressure in the pressure reducing balance device 2, pushing the balance slider 21 to the right, compressing the balance spring 22 and the pressure reducing spring 23 to maintain pressure balance, and adjusting the main oil pressure within the set pressure range. When the valve body 1 is depressurized, the one-way valve 65 opens quickly, the high pressure of the pressure reducing balance device 2 disappears, and the balance slider 21 moves to the left. Since the pressure of the balance spring 22 and the pressure reducing spring 23 loses balance, the high pressure quickly pushes the pressure reducing valve stem 25 to the left, shrinking the oil inlet and expanding the pressure reducing oil return port, while connecting the right quick return valve. The oil port enters the oil return chamber 403, so that the main oil pressure drops rapidly from 1.1~1.6MPa to below 0.5MPa, and then quickly returns to the set main pressure after the gear is switched; three: when the valve body 1 shifts gears, the working oil circuit 11 loses pressure, the pressure in the balancing valve stem boosting chamber 41 disappears, and the pressure in the energy storage boosting oil circuit 40 disappears, the second one-way valve 7 opens, the pressure in the energy storage chamber 46 disappears, and the energy storage spring 45 separates the balancing valve stem 42 and the energy storage valve sleeve 44, and each moves to the limit position in the opposite direction. At this time, the balancing valve stem 42 will release the energy storage buffer valve hole The oil inlet on 43 is blocked, and the hydraulic oil in the secondary energy storage buffer device 4 is emptied from the buffer oil return port; when the valve body 1 is shifted, the oil pressure of the first main oil circuit 8, the second main oil circuit 9 and the working oil circuit 11 rises, and the hydraulic oil enters the balance valve stem boosting chamber 41 through the control oil circuit of the balance valve stem boosting chamber 41; the oil pressure of the energy storage boosting oil circuit 40 rises at the same time, closing the one-way valve 65 and entering the energy storage chamber 46 through the dredging needle valve throttle nozzle 61, synchronously pushing the energy storage valve sleeve 44 and the balance valve stem 42 to move in opposite directions, compressing the energy storage spring 45, and at about 0.8~1.The working oil inlet of the secondary energy storage buffer device 4 is smoothly opened within 6S; Four: A signal block 57 is set at the tail of the operating valve stem 51. When the operating valve stem 51 is positioned in neutral, the signal block 57 is aligned with the contact electronic signal switch arranged above the valve body 1, and the electronic signal switch is turned on to transmit the neutral signal to the host. When the neutral gear is switched to the reverse gear or the forward gear, the electronic signal switch is closed; A hydraulic signal port is set at the corresponding position above the gear lever 56 of the valve body 1, and a hydraulic signal switch is installed. When the operating valve stem 51 is switched to the corresponding gear, the hydraulic signal switch is turned on to transmit the correct gear real-time signal to the host, so that the operator can grasp the gear information at any time; Five: When the loader needs to stop, turn on the drive gas / hydraulic pressure to push The pneumatic brake piston 343, the brake push rod 344, and the brake valve stem 32 compress the pneumatic spring 31 so that the brake valve stem 32 cuts off the first main oil circuit 8 and the second main oil circuit 9 and relieves the pressure through the brake valve stem 32 to connect the return oil port of the valve body 1; after the air / hydraulic pressure is removed, the pneumatic spring 31 pushes the brake valve stem 32 back to reset, the main oil circuit is connected to restore the main pressure, and the loader resumes the working state; Six: When the power cut-off valve 361 is in the closed state, the power cut-off spring 362 installed in the intake valve body 363 compresses and pushes the air valve stem 353 and the cylindrical piston 355 to move the brake valve stem 32 toward the inner axis, cutting off the working oil circuit 11 so that the working oil circuit 11 is connected to the return oil chamber 403. At this time, the oil pressure of the working oil circuit 11 is 0MPa; in this state, it reaches When the loader is started, even when the valve body 1 is in gear, the loader cannot move because the oil pressure of the working oil circuit 11 is cut off, thereby improving the reliability of safe operation. When the loader is not working or in the interval between operations under the motor starting state, the power cut-off valve 361 is not opened, and the main oil pressure of the valve body 1 is 0MPa. When it is necessary to open the power cut-off valve 361, an air pressure of ≥0.45MPa enters between the intake valve seat 365 and the intake valve stem 364 from the air inlet of the first pneumatic joint 369 of the air valve seat 352 to form a pressure chamber, and the residual air in the intake valve body 363 is discharged from the second pneumatic joint 368, the power cut-off spring 362 is compressed, and the intake valve stem 364 moves outward. At this time, the brake valve is opened by the action of the pneumatic spring 31. After the rod 32 is reset and the return oil is closed, the first main oil circuit 8 and the second main oil circuit 9 are connected and the working state is restored, and the loader can move; when the main oil circuit needs to be cut off, the air pressure is removed from the first pneumatic joint 369 of the intake valve seat 365, and the emergency air pressure of ≥0.45MPa enters from the interface of the second pneumatic joint 368. Under the thrust of the power cut-off spring 362, the intake valve rod 364, the cylindrical piston 355, and the brake valve rod 32 are pushed inward axially to cut off the first main oil circuit 8 and the second main oil circuit 9, so that the second main oil circuit 9 is connected with the return oil chamber 403. At this time, the working oil pressure is reduced to 0MPa; Seven: The safety valve chamber 132 is connected to the return oil chamber 403 of the valve body 1, and the safety opening pressure set by the safety valve spring 133 is 1.5 times, when the valve body 1 pressure relief system fails and the main oil pressure is instantly too high, the safety valve ball 131 moves down to open and relieve pressure, ensuring the safe use of the valve body 1.

[0041] The present invention provides a loader gearbox gear shift buffer multifunctional speed control valve and a control method thereof, which can add a secondary energy storage buffer device while not changing the docking size of the installation oil port of the original speed control valve, solve the technical problem of gear shift impact, and optimize the combination of various structures of the speed control valve to meet the differentiated needs of loader host manufacturers for gearboxes and speed control valves, and has a simple structure, is easy to use, and has high reliability.

[0042] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the implementation is not limited to the above embodiments, and a person skilled in the art may make various changes or modifications within the scope of the appended claims.

Claims

1. A multifunctional speed control valve for shifting and buffering of a loader gearbox, comprising a valve body (1), characterized in that: The valve body (1) is provided with a brake device (3), a pressure reducing balancing device (2) is installed in the valve body (1) located above the brake device (3), a secondary energy storage buffer device (4) is installed on the valve body (1) located on the left side of the brake device (3), and a speed shifting device (5) is installed on the valve body (1) located below the secondary energy storage buffer device (4). A first main oil circuit (8) connected to the pressure reducing balancing device (2) and the brake device (3) is provided in the valve body (1), and a second main oil circuit (9) connected to the brake device (3) and the secondary energy storage buffer device (4) is provided in the valve body (1) located below the first main oil circuit (8), and the second main oil circuit (9) is connected to the balancing oil circuit. (10) is connected, a working oil circuit (11) connected to the speed change device (5) and the secondary energy storage buffer device (4) is provided in the valve body (1) located below the second main oil circuit (9); the pressure reducing balancing device (2) includes a balancing valve chamber (28) connected to the left side of the pressure reducing valve chamber (26), a pressure reducing valve stem (25) with a pressure increasing hole (27) is installed in the pressure reducing valve chamber (26), the pressure reducing valve stem (25) is pressed and connected to the right end of the balancing slider (21) through a pressure reducing spring (23), a pressure regulating plate (24) is provided between the pressure reducing valve stem (25) and the pressure reducing spring (23), and the balancing slider (21) is pressed and connected through a balancing spring (22). The secondary energy storage buffer device (4) comprises an energy storage buffer valve hole (43) with a balancing valve stem (42), the energy storage buffer valve hole (43) is connected to the second main oil circuit (9), a balancing valve stem pressurizing chamber (41) is provided at the bottom of the balancing valve stem (42), the balancing valve stem pressurizing chamber (41) is connected to the working oil circuit (11), one end of the balancing valve stem (42) is sleeved on an energy storage spring (45), the energy storage spring (45) is sleeved on an energy storage valve sleeve (44), and the outer side of the balancing valve stem (42) is provided with a balancing valve stem pressurizing chamber (41). A cover plate (47) having a cover plate paper pad (48), the cover plate (47) being fixedly connected to the valve body (1) by means of a cover plate screw (49), an energy storage chamber (46) and an energy storage boosting oil circuit (40) being provided between the cover plate (47) and the energy storage valve sleeve (44), an energy storage throttle nozzle (401) being controllably connected to the energy storage chamber (46) being provided at the left end of the energy storage boosting oil circuit (40), a one-way valve oil circuit (66) and an energy storage oil return pipe (402) being connected thereto in sequence being provided on the energy storage boosting oil circuit (40) at the right end of the energy storage throttle nozzle (401), and an oil return chamber (403) being provided on the valve body (1) between the one-way valve oil circuit (66) and the energy storage oil return pipe (402);The brake device (3) comprises a brake valve chamber (33) connected to a first main oil circuit (8), the brake valve chamber (33) being provided with a connection to a second main oil circuit (9) and a balance oil circuit (10), a brake valve rod (32) with a pneumatic spring (31) being installed in the brake valve chamber (33), a valve body (1) at the left end of the brake valve rod (32) being provided with a pneumatically driven air valve body main oil circuit normally open brake assembly (35), the pneumatically driven air valve body main oil circuit normally open brake assembly (35) comprising an air valve body (356) installed at the left end of an air valve seat (352), and a valve body (356) installed at the right end of the air valve seat (352) A brake valve joint bolt (359) is provided, a gas valve stem (353) with a gas valve spring (357) is installed in the gas valve body (356), the gas valve stem (353) drives a cylindrical plug (355) connected to the brake valve joint bolt (359), the brake valve joint bolt (359) is fixedly installed on the gas valve seat (352) via a locking nut (358), the gas valve stem (353) is sealed and connected to the gas valve body (356) via a Y-shaped sealing ring (351), and the cylindrical plug (355) is sealed and connected to the brake valve joint bolt (359) via a cylindrical plug sealing ring (354); The control method of the loader gearbox shift buffer multifunctional speed control valve comprises the following steps:

1. The pressure reducing valve stem (25) is provided with a boost hole (27) and is connected to a boost chamber (28). When the oil pump inputs high-pressure oil, the oil enters the boost chamber (28) from the boost hole (27), and forms a high pressure between the pressure reducing balance device (2) and the pressure reducing valve stem (25), which compresses and moves the pressure reducing spring (23) inward, thereby realizing the oil return pressure reduction of the pressure reducing balance device (2). According to the pressure setting of the pressure reducing spring (23), the main pressure of the valve body (1) is set between 1.1 and 1.6 MPa; Second: When the pressure of the valve body (1) increases, the check valve (65) automatically closes, and oil enters through the throttle hole (62), so that high pressure is formed in the pressure reducing balance device (2), pushing the balance slide (21) to the right, compressing the balance spring (22) and the pressure reducing spring (23) to maintain pressure balance, and adjusting the main oil pressure within the set pressure range. When the pressure of the valve body (1) is relieved, the check valve (65) quickly opens, the high pressure of the pressure reducing balance device (2) disappears, and the balance slide (21) moves to the left. Since the pressure of the balance spring (22) and the pressure reducing spring (23) loses balance, the high pressure quickly pushes the pressure reducing valve stem (25) to the left, shrinking the oil inlet and expanding the pressure reducing oil return port. At the same time, the right quick oil return port is connected to enter the oil return chamber (403), so that the main oil pressure quickly drops from 1.1~1.6MPa to below 0.5MPa, and then quickly returns to the set main pressure after the gear is switched; 3. When the valve body (1) shifts gears, the working oil circuit (11) loses pressure, the pressure in the boosting chamber (41) of the balancing valve stem disappears, and the pressure in the boosting oil circuit (40) disappears at the same time. The second one-way valve (7) opens, and the pressure in the accumulating chamber (46) disappears. The accumulating spring (45) separates the balancing valve stem (42) and the accumulating valve sleeve (44), and each moves in opposite directions to a limit position. At this time, the balancing valve stem (42) blocks the oil inlet on the accumulating buffer valve hole (43). At this time, the hydraulic oil in the secondary accumulating buffer device (4) returns from the buffer. The valve body (1) is emptied from the outlet; when the valve body (1) is shifted, the oil pressures of the first main oil circuit (8), the second main oil circuit (9) and the working oil circuit (11) rise again, and the hydraulic oil enters the balancing valve stem boosting chamber (41) through the control oil circuit of the balancing valve stem boosting chamber (41); the oil pressure of the energy storage boosting oil circuit (40) rises at the same time, closing the one-way valve (65) and entering the energy storage chamber (46) through the dredging needle valve throttle nozzle (61), synchronously pushing the energy storage valve sleeve (44) and the balancing valve stem (42) to move in opposite directions, compressing the energy storage spring (45), and the oil pressure of the energy storage boosting oil circuit (40) rises at the same time, closing the one-way valve (65) and entering the energy storage chamber (46) through the dredging needle valve throttle nozzle (61), and ... simultaneously pushing the energy storage valve sleeve (44) and the balancing valve stem (42) to move in opposite directions, compressing the energy storage spring (45), and the oil pressure of the energy storage boosting oil circuit (40) rises at the same time, closing the one-way valve (65) and entering the energy storage chamber (46) through the dredging needle valve throttle nozzle (61), and simultaneously pushing the energy storage valve sleeve (44) and the balancing valve stem (42) to move in opposite directions, compressing the energy storage spring (45), and the oil pressure of the energy storage boosting oil circuit (40) rises at the sameThe working oil inlet of the secondary energy storage buffer device (4) is opened smoothly within 6 seconds; Fourth: A signal block (57) is provided at the tail of the operating valve stem (51). When the operating valve stem (51) is positioned at the neutral position, the signal block (57) is aligned with the contact type electronic signal switch provided above the valve body (1), and the electronic signal switch is turned on to transmit the neutral signal to the main engine. When the neutral position is switched to the reverse gear or the forward gear, the electronic signal switch is turned off; hydraulic signal ports are provided at corresponding positions above the gear lever (56) of the valve body (1), and a hydraulic signal switch is installed. When the operating valve stem (51) is switched to the corresponding gear position, the hydraulic signal switch is turned on to transmit the correct gear position real-time signal to the main engine, so that the operator can grasp the gear position information at any time; Five: When the loader needs to stop during operation, the driving air / hydraulic pressure is turned on to push the brake piston (343), the brake push rod (344), and the brake valve stem (32), compressing the pneumatic spring (31) so that the brake valve stem (32) cuts off the first main oil circuit (8) and the second main oil circuit (9) and releases the pressure through the brake valve stem (32) to connect to the oil return port of the valve body (1); after the air / hydraulic pressure is removed, the pneumatic spring (31) pushes the brake valve stem (32) back to reset, the main oil circuit is connected to restore the main pressure, and the loader returns to the working state; Sixth: When the power cut-off valve (361) is closed, the power cut-off spring (362) installed in the intake valve body (363) is compressed to push the air valve stem (353) and the cylindrical piston (355) against the brake valve stem (32) to move inwardly, cutting off the working oil path (11) so that the working oil path (11) is connected to the oil return chamber (403). At this time, the oil pressure of the working oil path (11) is 0 MPa. In this state, the loader can be started. Even if the valve body (1) is in the gear state, the loader cannot move because the oil pressure of the working oil path (11) is cut off. The reliability of safe operation is improved; when the loader is not operating or in the interval between operations in the motor starting state, the power cut-off valve (361) is not opened, and the main oil pressure of the valve body (1) is 0MPa; when the power cut-off valve (361) needs to be opened, a gas pressure of ≥0.45MPa enters between the intake valve seat (365) and the intake valve stem (364) from the intake port of the first pneumatic joint (369) of the gas valve seat (352), so that a pressure chamber is formed, and the residual gas in the intake valve body (363) is discharged from the second pneumatic joint (368), and the power cut-off spring (362) is opened. ) is compressed, and the intake valve stem (364) moves outward. At this time, the brake valve stem (32) is reset by the action of the pneumatic spring (31). After the return oil is closed, the first main oil circuit (8) and the second main oil circuit (9) are connected to restore the working state, and the loader can move. When it is necessary to cut off the main oil circuit, the air pressure is removed from the first pneumatic joint (369) of the intake valve seat (365), and an emergency air pressure of ≥0.45MPa is introduced from the interface of the second pneumatic joint (368). Under the thrust of the power cut-off spring (362), the intake valve stem (364) and the cylindrical piston (35 5) The brake valve rod (32) moves axially inward, cutting off the first main oil circuit (8) and the second main oil circuit (9), so that the second main oil circuit (9) is connected to the oil return chamber (403). At this time, the working oil pressure is reduced to 0 MPa. Seven: The safety valve chamber (132) is connected to the oil return chamber (403) of the valve body (1). The safety opening pressure set by the safety valve spring (133) is 1.5 times the main oil pressure. When the pressure relief system of the valve body (1) fails and the main oil pressure is instantly too high, the safety valve ball (131) moves downward to open and relieve pressure, thereby ensuring the safe use of the valve body (1).

2. The loader gearbox shift buffer multifunctional speed control valve according to claim 1, characterized in that: A guide needle valve throttle nozzle assembly (6) is installed on the valve body (1) located on the right side of the balancing oil circuit (10). The guide needle valve throttle nozzle assembly (6) includes a one-way valve oil circuit (66) arranged at the bottom end of the valve body (1) and connected to the balancing valve chamber (28). A one-way valve (65) with a one-way valve baffle (64) is installed at the inlet of the one-way valve oil circuit (66). A guide needle valve throttle nozzle (61) is provided on the valve body (1) above the one-way valve (65). The guide needle valve throttle nozzle (61) is connected to the balancing oil circuit (10) through a throttle hole (62). A guide needle valve (63) is provided in the throttle hole (62).

3. The loader gearbox shift buffer multifunctional speed control valve according to claim 2, characterized in that: A second one-way valve (7) is installed on the valve body (1) located on the left side of the guide needle valve (63). The second one-way valve (7) includes a control ball (72) installed on the one-way valve oil circuit (66). A second one-way valve baffle (71) is installed on the right end of the control ball (72). A one-way valve transition oil circuit (73) connected to the energy storage and pressure boosting oil circuit (40) is provided on the valve body (1) located below the one-way valve oil circuit (66).

4. The loader transmission shift buffer multifunctional speed control valve according to any one of claims 1 to 3, characterized in that: The brake device (3) comprises a brake valve chamber (33) connected to a first main oil circuit (8), the brake valve chamber (33) being connected to a second main oil circuit (9) and a balance oil circuit (10), a brake valve rod (32) with a pneumatic spring (31) being installed in the brake valve chamber (33), a valve body (1) at the left end of the brake valve rod (32) being provided with a closed main oil circuit normally open brake assembly (34), the closed main oil circuit normally open brake assembly (34) comprising a brake piston (343) movably connected to a brake valve (341), the brake piston (343) being drivingly connected to the left end of a brake push rod (344), and a drive interface (342) being provided at the left end of the brake piston (343).

5. The loader transmission shift buffer multifunctional speed control valve according to any one of claims 1 to 3, characterized in that: The brake device (3) comprises a brake valve chamber (33) connected to a first main oil circuit (8), the brake valve chamber (33) being provided with a communication connection to a second main oil circuit (9) and a balance oil circuit (10), a brake valve rod (32) with a pneumatic spring (31) being installed in the brake valve chamber (33), a valve body (1) at the left end of the brake valve rod (32) being provided with a pneumatically driven main oil circuit normally closed power cut-off assembly (36), the pneumatically driven main oil circuit normally closed power cut-off assembly (36) comprising an intake valve body respectively installed at the left and right ends of an intake valve seat (365) (363) and a connector body (366), a power cut-off valve (361) with a second pneumatic connector (368) is installed at the left end of the intake valve body (363), an intake valve stem (364) is provided in the intake valve body (363), the intake valve stem (364) is pressed and connected to the left side of the intake valve seat (365) through a power cut-off spring (362), the right end of the intake valve stem (364) is driven and connected to the cylindrical plug (367), and a first pneumatic connector (369) is provided at the bottom of the intake valve seat (365) and is in communication with the intake valve body (363).

6. The loader transmission shift buffer multifunctional speed control valve according to any one of claims 1 to 3, characterized in that: The speed change gear shifting device (5) comprises an operating valve rod (51) installed in an operating valve cavity (52), a shift rod (56) fixedly connected to the operating valve rod (51) is provided at the right end thereof, a signal block (57) is provided at the end of the shift rod (56), an embedded dust cover (59) is provided at the left side of the operating valve rod (51), a limit steel ball (54) with a limit spring (53) is installed at both upper and lower sides of the shift rod (56), the limit steel ball (54) is pressed and contacted with the shift rod (56), a shift screw plug (55) for limiting is provided on the outer side of the limit steel ball (54) below the shift rod (56), and a limit signal screw plug (58) matched with the signal block (57) is provided on the valve body (1) located on the right side of the signal block (57).

7. The loader transmission gear shift buffer multifunctional speed control valve according to any one of claims 1 to 3, characterized in that: The speed shifting device (5) comprises an operating valve rod (51) installed in an operating valve cavity (52); a shift rod (56) fixedly connected to the operating valve rod (51) is provided at the right end thereof; a signal block (57) is provided at the end of the shift rod (56); an external buckle-type dust cover (50) is provided on the left side of the operating valve rod (51); the external buckle-type dust cover (50) comprises a cover shell (501) installed on the right side of a valve body (1); a skeleton oil seal (504) sealingly connected to the valve body (1) is provided in the cover shell (501); the skeleton oil seal (504) is sealingly connected to the valve body (1) via a combined sealing ring (502); a limit retaining ring (503) is provided on the left side of the skeleton oil seal (504); and a limit signal screw plug (58) matched with the signal block (57) is provided on the valve body (1) located on the right side of the signal block (57).

8. The multifunctional speed control valve for shifting and buffering of a loader gearbox according to claim 1, characterized in that: The bottom end of the valve body (1) is provided with a main oil circuit overload protection assembly (13) which is controllably connected to the first main oil circuit (8). The main oil circuit overload protection assembly (13) comprises a safety valve ball (131). The safety valve ball (131) is compressed and connected to the upper end of a safety valve chamber (132) via a safety valve spring (133). A safety valve bolt (135) with a safety valve sealing ring (134) is installed at the bottom end of the safety valve chamber (132).

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