Novel travel motor double-speed switching system and method

Abstract

The invention discloses a novel travel motor double-speed switching system and method. The novel travel motor double-speed switching system comprises a balance valve assembly, a brake assembly, a travel motor, a throttling plug, a first one-way valve, a second one-way valve, a third one-way valve, a double-speed switching valve assembly and a variable assembly. A double-speed valve element of the double-speed switching valve assembly achieves automatic double-speed switching through the diameter difference of the outer circle face, the structure is simple, and automatic double-speed switching is sensitive. And annular space damping is formed by the damping ring and the mounting hole, so that the opening speed of a double-speed valve port is slowed down, the extension speed of a variable plunger is slowed down, the pressure impact when the motor is switched from low speed to high speed is reduced, the shaking problem when the walking motor is switched from low speed to high speed is slowed down, and the motor operation comfort is improved. When the motor is started at a high speed, oil at the port Ps reaches the bottom of the variable plunger before oil at the port A through the combination of the first one-way valve and the third one-way valve, the swash plate is pushed to be in a small-displacement state, the motor is stably started in the small-displacement state, and pressure impact caused by displacement change in the starting process is avoided.

Description

Technical Field

[0001] The present invention relates to a novel dual-speed switching system and method for a traveling motor, belonging to the technical field of engineering machinery. Background Art

[0002] The travel drive of engineering machinery such as crawler cranes and crawler excavators is a swash plate axial piston motor. The travel drive is divided into high speed and low speed. The high speed and low speed are switched by changing the motor displacement by connecting / cutting off the external control pilot oil.

[0003] During the high-speed and low-speed switching process, the travel motor often produces shocks due to the large inertia load of the entire machine, which is caused by the instantaneous change of working pressure. This gives the driver a bad operating experience. At the same time, frequent pressure shocks will have an adverse effect on the hydraulic system, greatly reducing the operating performance and life of the excavator.

[0004] Therefore, those skilled in the art are in urgent need of solving the technical problems arising from existing travel motors. Summary of the Invention

[0005] Objective: To overcome the deficiencies in the prior art, the present invention provides a novel dual-speed switching system and method for a travel motor.

[0006] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is:

[0007] In the first aspect, a new type of walking motor dual-speed switching system includes: a dual-speed switching valve assembly, a throttle plug, a first one-way valve, a second one-way valve and a third one-way valve. The dual-speed switching valve assembly, the throttle plug, the first one-way valve, the second one-way valve and the third one-way valve are integrated in the same valve body. The dual-speed switching valve assembly includes a dual-speed valve core, a dual-speed spring, a pilot oil inlet plug and a plug. A valve cavity is provided in the valve body, and a first dual-speed valve core mounting hole, a second dual-speed valve core mounting hole and a countersunk groove are provided in the valve cavity. The valve body is also provided with an oil port T connected to the valve cavity, an oil port A, a first oil port P, a second oil port P, a first pilot oil channel, a left-end control oil channel port and a right-end oil drain port; the first oil port P is connected to the valve cavity through the oil channel in the valve body, the first oil port P is provided with a first one-way valve, and the second oil port P is connected to the valve cavity through the oil channel in the valve body. The second oil port P is connected to the valve chamber. A third one-way valve is provided at one end of the first pilot oil passage, and the other end is connected to the valve chamber. The oil port T is connected to the valve chamber via the oil circuit within the valve body and is provided with a throttle plug. The oil port A is connected to the valve chamber via the oil circuit within the valve body. The left-end control oil passage port is connected to the valve chamber via the oil circuit within the valve body, and the right-end oil drain port is connected to the valve chamber via the oil circuit within the valve body. A pilot oil inlet plug is provided at one end of the valve chamber, and a plug is provided at the other end of the valve chamber.

[0008] As a preferred solution, the dual-speed valve core includes a first-section valve core, a second-section valve core, a third-section valve core, a fourth-section valve core and a fifth-section valve core, and the first-section valve core, the second-section valve core, the third-section valve core, the fourth-section valve core and the fifth-section valve core are connected in sequence.

[0009] As a preferred embodiment, it further includes: a balancing valve assembly, a brake assembly, a travel motor, and a variable speed assembly. The oil port A1 of the balancing valve assembly is in communication with the oil port A of the travel motor, and the oil port A1 of the balancing valve assembly is also connected to the oil inlet of the first one-way valve. The oil port B1 of the balancing valve assembly is in communication with the oil port B of the travel motor, and the oil port B1 of the balancing valve assembly is also connected to the oil inlet of the second one-way valve. The oil outlet of the first one-way valve and the oil outlet of the second one-way valve are both connected to the oil port P of the dual-speed switching valve assembly. The right control end of the dual-speed switching valve assembly is connected to the pilot oil circuit, and the pilot oil circuit is also connected to the oil inlet of the third one-way valve. The oil outlet of the third one-way valve is also connected to the oil port P of the dual-speed switching valve assembly. The oil port P of the balancing valve assembly is connected to the oil port of the brake assembly. The oil port P of the balancing valve assembly is also connected to the left control end of the dual-speed switching valve assembly. The clutch end of the brake assembly is connected to the brake end of the travel motor. The swash plate control end of the travel motor is connected to the output end of the variable speed assembly. The oil port of the variable speed assembly is connected to the oil port A of the dual-speed switching valve assembly. The oil port T of the dual-speed switching valve assembly is connected to the oil tank. The oil port T of the balancing valve assembly is connected to the oil tank. The oil overflow port of the travel motor is connected to the oil tank.

[0010] The oil port A of the balancing valve assembly is also connected to the oil inlet of the fourth one-way valve, and the oil outlet of the fourth one-way valve is connected to the left control end of the balancing valve assembly 1. The oil port A of the balancing valve assembly is also connected to the left control end of the balancing valve assembly through an oil return circuit. The oil port B of the balancing valve assembly is also connected to the oil inlet of the fifth one-way valve, and the oil outlet of the fifth one-way valve is connected to the right control end of the balancing valve assembly. The oil port B of the balancing valve assembly is also connected to the right control end of the balancing valve assembly through an oil return circuit.

[0011] As a preferred solution, the pilot oil circuit is further connected to the oil tank via an annular gap damper.

[0012] As a preferred solution, the oil port A1 of the balancing valve assembly is further connected to the oil port B1 of the balancing valve assembly through a first relief valve.

[0013] As a preferred solution, the oil port B1 of the balancing valve assembly is further connected to the oil port A1 of the balancing valve assembly through a second relief valve.

[0014] In the second aspect, a novel operating method of a dual-speed switching system for a travel motor specifically includes:

[0015] When moving forward, the oil passes through the oil port A of the balance valve assembly, the oil port A1 of the balance valve assembly, and the oil port A of the travel motor into the working chamber of the travel motor, and the pressure is P A At the same time, the oil in port A also pushes the balancing valve assembly to the right. The oil port A of the balancing valve assembly is also connected to the oil port P of the balancing valve assembly. The oil enters the working chamber of the brake assembly, overcomes the spring force of the brake assembly, and releases the mechanical brake of the motor.

[0016] The valve port between the oil port B of the travel motor and the oil return chamber of the travel motor is opened, and the oil return chamber of the travel motor is connected to the oil port B of the travel motor.

[0017] The oil in port A1 of the balancing valve assembly also opens the valve port of the first one-way valve. The oil acts on the dual-speed valve core through the oil port P, and the second and third one-way valves are closed under the action of spring force and oil.

[0018] The pilot oil inlet plug is shut off, and the two-speed valve core is in the left position due to the force F1 of the two-speed spring. The oil port A of the two-speed switching valve assembly is connected to the oil port T. The oil of the variable component flows into the oil tank through the two-speed switching valve assembly and the throttle plug. The swash plate operates at a large angle, and the travel motor is in a large displacement state. When the oil pressure at the travel motor's oil port A overcomes the motor load, the travel motor achieves low-speed travel.

[0019] Alternatively, when the travel motor switches from low-speed travel to high-speed travel, the pilot oil inlet plug is connected to the external control pilot oil, and the pilot oil acts on the left side of the dual-speed valve core.

[0020] When Ps * A1>P A *A2 + F1, where Ps is the pilot oil pressure, A1 is the pilot oil effective area, A2 is the oil effective area at the oil port P of the dual-speed switching valve assembly, P A is the oil pressure at the oil port P of the two-speed switching valve assembly, and F1 is the force of the two-speed spring of the two-speed switching valve group when traveling at low speed.

[0021] The two-speed valve core moves to the right. During the movement, part of the pilot oil will leak to the T port through the annular gap damping. The two-speed switching valve group opens slowly and smoothly. At the same time, the two-speed switching valve assembly is in the right position, and the oil port P of the two-speed switching valve assembly is connected to the oil port A.

[0022] The oil at the oil port P of the two-speed switching valve assembly passes through the smoothly opened two-speed valve core and enters the bottom of the variable assembly, pushing the variable plunger to slowly extend. The variable plunger pushes the swash plate to rotate smoothly to the small displacement state, and the motor achieves high-speed travel.

[0023] Or, when the load of the travel motor increases during high-speed travel, the oil pressure P A Increase.

[0024] When Ps * A1<P A *When A2 + F2, F2 is the force of the dual-speed spring of the dual-speed switching valve group during high-speed travel.

[0025] The dual-speed valve core is under the oil pressure P A The oil port A of the dual-speed switching valve assembly is connected to the oil port T, and the oil flows into the oil tank through the variable assembly, the dual-speed switching valve assembly and the throttle plug. The variable plunger slowly retracts into the housing under the action of the swash plate, and the swash plate rotates smoothly to the large displacement state.

[0026] Alternatively, when the travel motor is started at high speed, the pilot oil inlet plug receives externally controlled pilot oil. This pilot oil shifts the two-speed valve spool to the left. When the pilot oil pressure rises to a level sufficient to overcome the force F1 of the right-side two-speed spring, it pushes the two-speed valve spool to the right, connecting port P and port A of the two-speed switching valve assembly. Simultaneously, the pilot oil acts on the third check valve, opening it and closing the first and second check valves. The pilot oil then flows through the third check valve and the two-speed switching valve assembly to the bottom of the variable displacement assembly's plunger, extending it and rotating the swash plate to the motor's low-displacement position.

[0027] The oil flows through the oil port A of the balance valve assembly, the oil port A1 of the balance valve assembly, and the oil port A of the travel motor into the working chamber of the travel motor. The pressure is P A At the same time, the oil in port A also pushes the balancing valve assembly to the right. The oil port A of the balancing valve assembly is also connected to the oil port P of the balancing valve assembly. The oil enters the working chamber of the brake assembly, overcomes the spring force of the brake assembly, and releases the mechanical brake of the motor.

[0028] The valve port between the oil port B of the travel motor and the oil return chamber of the travel motor is opened, and the oil return chamber of the travel motor is connected to the oil port B of the travel motor.

[0029] When the pressure on the oil port A side of the travel motor overcomes the motor load, the motor starts smoothly at high speed.

[0030] When the oil pressure P at port A of the travel motor A When the force acting on the first one-way valve and the third one-way valve is greater than the force acting on the pilot oil inlet plug, the first one-way valve opens and the third one-way valve closes, and the oil at the oil port P of the two-speed switching valve assembly enters the bottom of the variable assembly plunger through the two-speed switching valve assembly, so that the motor always maintains a high-speed state.

[0031] Alternatively, when the travel motor moves backward, oil enters the oil port B of the balancing valve assembly, the balancing valve assembly moves to the left, the oil port A of the balancing valve assembly is connected to the oil port A1, and the oil port B of the balancing valve assembly is connected to the oil port B1 and the oil port P. The working process is the same as the above method.

[0032] As a preferred solution, the effective area of ​​the annular gap damping is The expression is as follows:

[0033] =

[0034] Wherein, D1 is the diameter of the first dual-speed valve core installation hole, and d2 is the diameter of the second section valve core.

[0035] As a preferred solution, the pilot oil effective area A1 is expressed as follows:

[0036] A1=π / 4*d1 2

[0037] In the base, π is the ratio of the circumference of a circle to the diameter of a circle, and d1 is the diameter of the first valve core.

[0038] As a preferred solution, the oil effective area A2 at the oil port P of the dual-speed switching valve assembly is expressed as follows:

[0039] A2=π / 4*(d1 2 -d2 2 )

[0040] Wherein, π is the ratio of circumference to pi, d1 is the diameter of the first section of the valve core, and d2 is the diameter of the second section of the valve core.

[0041] Beneficial effects: The present invention provides a novel dual-speed switching system and method for a walking motor, in which the dual-speed valve core realizes automatic dual-speed switching through the diameter difference of the outer circle, has a simple structure, and the automatic dual-speed switching is sensitive; an annular gap damping is formed with the mounting hole to slow down the opening speed of the dual-speed valve port, slow down the extension speed of the variable plunger, and reduce the pressure shock when the motor switches from low speed to high speed, thereby reducing the jitter problem of the walking motor when switching from low speed to high speed and improving the comfort of motor operation.

[0042] Furthermore, in the present invention, when the motor starts at high speed, the oil at the Ps port passes through the combination of the one-way valves a and c and reaches the bottom of the variable plunger before the oil at the A port, pushing the swash plate to a small displacement state, so that the motor starts smoothly in the small displacement state and avoids pressure shock caused by displacement changes during the starting process.

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] (1) This invention designs a new dual-speed switching valve core. By using the diameter difference of the valve core itself, the system oil acts on different areas at both ends of the dual-speed valve, realizing automatic dual-speed switching of the motor. The dual-speed switching valve structure is simplified, making the switching process simple and stable, while reducing the valve core processing cost.

[0045] (2) The present invention increases the damping of the dual-speed valve ring gap, slows down the opening speed of the dual-speed valve port, slows down the extension speed of the variable plunger, reduces the pressure impact when the motor switches from low speed to high speed, and alleviates the jitter of the travel motor when switching from low speed to high speed.

[0046] (3) The present invention adds a one-way valve to the variable displacement system. When the motor starts at high speed, the pilot oil opens the dual-speed valve port. At the same time, the pilot oil passes through the one-way valve and the dual-speed valve port to the bottom of the variable displacement plunger. The variable displacement plunger extends under the action of the pilot oil, and the swash plate first shifts to a small displacement, putting the motor in a high-speed state, and then starting the motor. This can eliminate the system pressure shock caused by the simultaneous variable displacement of the motor during high-speed starting, allowing the travel motor to start smoothly at high speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is the hydraulic principle diagram of the new travel motor dual-speed switching system.

[0048] Figure 2 This is a schematic diagram of the structure of the dual-speed switching valve assembly when traveling at low speed.

[0049] Figure 3 This is a structural diagram of the dual-speed switching valve assembly when running at high speed.

[0050] Figure 4 It is a structural schematic diagram of the dual-speed valve core of the dual-speed switching valve assembly.

[0051] Figure 5 Schematic diagram of the valve port area change curve of the dual-speed switching valve assembly over time. DETAILED DESCRIPTION

[0052] The following is a clear and complete description of the technical solutions in the examples of the present invention, in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0053] The present invention will be further described below with reference to specific embodiments.

[0054] Example 1:

[0055] This embodiment introduces a new type of walking motor dual-speed switching system. Figure 1 As shown, it includes: a balancing valve assembly 1, a brake assembly 2, a travel motor 3, a throttle plug 4, a first one-way valve 5, a second one-way valve 6, a third one-way valve 7, a dual-speed switching valve assembly 8, and a variable assembly 9.

[0056] The balancing valve assembly 1 includes: oil port A, oil port B, oil port P, oil port A1, oil port B1, and oil port T.

[0057] The dual-speed switching valve assembly 8 includes: an oil port P, an oil port A, and an oil port T.

[0058] The oil port A1 of the balancing valve assembly 1 is in communication with the oil port A of the travel motor 3. The oil port A1 of the balancing valve assembly 1 is also connected to the oil inlet of the first one-way valve 5. The oil port B1 of the balancing valve assembly 1 is in communication with the oil port B of the travel motor 3. The oil port B1 of the balancing valve assembly 1 is also connected to the oil inlet of the second one-way valve 6. The oil outlet of the first one-way valve 5 and the oil outlet of the second one-way valve 6 are both connected to the oil port P of the dual-speed switching valve assembly 8. The right control end of the dual-speed switching valve assembly 8 is connected to the pilot oil circuit, which is also connected to the oil inlet of the third one-way valve 7. The oil outlet of the third one-way valve 7 is also connected to the oil port P of the dual-speed switching valve assembly 8. The oil port P of the balancing valve assembly 1 is connected to the oil port of the brake assembly 2. The oil port P of the balancing valve assembly 1 is also connected to the left control end of the dual-speed switching valve assembly 8. The clutch end of the brake assembly 2 is connected to the brake end of the travel motor 3. The swash plate control end of the travel motor 3 is connected to the output end of the variable assembly 9. The oil port of the variable assembly 9 is connected to the oil port A of the dual-speed switching valve assembly 8. The oil port T of the dual-speed switching valve assembly 8 is connected to the oil tank. The oil port T of the balancing valve assembly 1 is connected to the oil tank. The oil overflow port of the travel motor 3 is connected to the oil tank.

[0059] The oil port A of the balancing valve assembly 1 is also connected to the oil inlet of the fourth one-way valve, and the oil outlet of the fourth one-way valve is connected to the left control end of the balancing valve assembly 1. The oil port A of the balancing valve assembly 1 is also connected to the left control end of the balancing valve assembly 1 through an oil return circuit. The oil port B of the balancing valve assembly 1 is also connected to the oil inlet of the fifth one-way valve, and the oil outlet of the fifth one-way valve is connected to the right control end of the balancing valve assembly 1. The oil port B of the balancing valve assembly 1 is also connected to the right control end of the balancing valve assembly 1 through an oil return circuit.

[0060] Furthermore, the pilot oil circuit is also connected to the oil tank via an annular gap damper 10 .

[0061] Furthermore, the oil port A1 of the balancing valve assembly 1 is also connected to the oil port B1 of the balancing valve assembly 1 through the first relief valve 11 .

[0062] Furthermore, the oil port B1 of the balancing valve assembly 1 is also connected to the oil port A1 of the balancing valve assembly 1 through the second relief valve 12 .

[0063] Furthermore, a throttle plug 4 is provided on the pipeline between the oil port T of the dual-speed switching valve assembly 8 and the oil tank.

[0064] Furthermore, the oil port A of the travel motor 3 is also provided with a first pressure measuring point.

[0065] Furthermore, the oil port B of the travel motor 3 is also provided with a second pressure measuring point.

[0066] Further, such as Figure 2-3 As shown, the dual-speed switching valve assembly 8, the throttle plug 4, the first one-way valve 5, the second one-way valve 6 and the third one-way valve 7 are integrated into the same valve body 13. The dual-speed switching valve assembly 8 includes a dual-speed valve core 801, a dual-speed spring 802, a pilot oil inlet plug 803 and a plug 804. A valve cavity is provided in the valve body 13. The valve cavity is provided with a first dual-speed valve core mounting hole 14, a second dual-speed valve core mounting hole 15 and a countersunk groove 16. The valve body is also provided with an oil port T17 connected to the valve cavity, an oil port A18, a first oil port P19, a second oil port P20, a first pilot oil channel 21, a left-end control oil channel port 22 and a right-end oil drain port 23. The first oil port P is connected to the valve cavity through the oil circuit in the valve body 13. The first oil port P is provided with a first one-way valve 5. The second oil port P is connected to the valve cavity through the oil circuit in the valve body 13. The oil circuit within the valve body 13 communicates with the valve cavity. The second oil port P is provided with a second check valve 6. A third check valve 7 is provided at one end of the first pilot oil passage, and the other end communicates with the valve cavity. The oil port T communicates with the valve cavity through the oil circuit within the valve body 13 and is provided with a throttle plug 4. The oil port A communicates with the valve cavity through the oil circuit within the valve body 13. The left-end control oil passage port communicates with the valve cavity through the oil circuit within the valve body 13, and the right-end oil drain port communicates with the valve cavity through the oil circuit within the valve body 13. A pilot oil inlet plug 803 is provided at one end of the valve cavity, and a plug 804 is provided at the other end.

[0067] Furthermore, the right end oil drain port is used to be connected to the oil tank through the annular gap damper 10, and the left end control oil channel port is used to be connected to the oil port P of the balancing valve assembly 1.

[0068] Further, such as Figure 4 As shown, the dual-speed valve core 801 includes a first-section valve core 8011, a second-section valve core 8012, a third-section valve core 8013, a fourth-section valve core 8014 and a fifth-section valve core 8015. The first-section valve core, the second-section valve core, the third-section valve core, the fourth-section valve core and the fifth-section valve core are connected in sequence. The diameter of the first-section valve core is d1, the diameter of the second-section valve core is d2, the diameter of the third-section valve core is d3, the diameter of the fourth-section valve core is d4, and the diameter of the fifth-section valve core is d5. The diameter of the effective surface of the external control pilot oil Ps is d1, and the diameters of the effective surfaces of the oils in the first oil port P and the second oil port P are d1 and d2, respectively.

[0069] Furthermore, the diameter of the first dual-speed valve core mounting hole 14 is D1, the diameter of the second dual-speed valve core mounting hole 15 is D2, and the diameter of the undercut groove 16 is D3.

[0070] Example 2:

[0071] This embodiment introduces a novel operating method of a dual-speed switching system for a travel motor, specifically including:

[0072] When moving forward, the oil flows through the oil port A of the balance valve assembly, the oil port A1 of the balance valve assembly, and the oil port A of the travel motor into the working chamber of the travel motor, with a pressure of P A At the same time, the oil in port A also pushes the balancing valve assembly to the right. The oil port A of the balancing valve assembly is also connected to the oil port P of the balancing valve assembly. The oil enters the working chamber of the brake assembly, overcomes the spring force of the brake assembly, and releases the mechanical brake of the motor.

[0073] The valve port between the oil port B of the travel motor and the oil return chamber of the travel motor is opened, and the oil return chamber of the travel motor is connected to the oil port B of the travel motor.

[0074] The oil in port A1 of the balancing valve assembly also opens the valve port of the first one-way valve. The oil acts on the dual-speed valve core through port P, with an effective area of ​​A2. The second and third one-way valves are closed under the action of spring force and oil.

[0075] The pilot oil inlet plug is shut off, and the two-speed valve core is in the left position due to the force F1 of the two-speed spring. The oil port A of the two-speed switching valve assembly is connected to the oil port T. The oil of the variable component flows into the oil tank through the two-speed switching valve assembly and the throttle plug. The swash plate operates at a large angle, and the travel motor is in a large displacement state. When the oil pressure at the travel motor's oil port A overcomes the motor load, the travel motor achieves low-speed travel.

[0076] When the travel motor switches from low-speed travel to high-speed travel, the pilot oil inlet plug is connected to the external control pilot oil, and the pilot oil acts on the left side of the dual-speed valve core, with an effective area of ​​A1.

[0077] When Ps * A1>P A *A2 + F1, where Ps is the pilot oil pressure, A1 is the pilot oil effective area, A2 is the oil effective area at the oil port P of the dual-speed switching valve assembly, P A is the oil pressure at the oil port P of the two-speed switching valve assembly, and F1 is the force of the two-speed spring of the two-speed switching valve group when traveling at low speed.

[0078] The two-speed spool moves to the right. During the movement, part of the pilot oil will leak to the T port through the annular gap damping to filter the pressure shock caused by the sudden connection of the pilot oil inlet plug. At the same time, the pilot oil leakage through the annular gap damping slows down the pressure building process of the pilot oil on the left side of the two-speed spool. Figure 5 As shown in the figure, due to the leakage of the annular gap damping ϴ, the pressure buildup process of the pilot oil inlet plug is slow and steady, and the two-speed switching valve group opens slowly and steadily. At the same time, the two-speed switching valve assembly is in the right position, and the oil port P and oil port A of the two-speed switching valve assembly are connected.

[0079] The oil at the oil port P of the two-speed switching valve assembly passes through the smoothly opened two-speed valve core and enters the bottom of the variable assembly, pushing the variable plunger to slowly extend. The variable plunger pushes the swash plate to rotate smoothly to the small displacement state, and the motor achieves high-speed travel.

[0080] Among them, from Figure 5 It can be seen that the annular gap damping can effectively filter the pressure impact of the Ps port on the dual-speed valve core. The dual-speed valve core opens later than when there is no annular gap damping, and the valve port area changes smoothly, causing the variable plunger to slowly extend, pushing the swash plate to rotate smoothly to the small displacement state, which can reduce the pressure impact caused by the motor variable.

[0081] When the load of the travel motor increases at high speed, the oil pressure P A To avoid motor overload, the motor needs to be switched to a large displacement state.

[0082] When Ps * A1<P A *When A2 + F2, F2 is the force of the dual-speed spring of the dual-speed switching valve group during high-speed travel.

[0083] The dual-speed valve core is under the oil pressure P A The oil port A of the dual-speed switching valve assembly is connected to the oil port T, and the oil flows into the oil tank through the variable assembly, the dual-speed switching valve assembly and the throttle plug. The variable plunger slowly retracts into the housing under the action of the swash plate, and the swash plate rotates smoothly to the large displacement state.

[0084] Among them, the new dual-speed switching valve assembly realizes annular gap damping and automatic dual-speed switching through diameter difference. The valve core structure is simple and the switching is smooth.

[0085] When the travel motor starts at high speed, the pilot oil inlet plug receives external pilot oil. This pilot oil shifts the two-speed valve spool to the left. When the pilot oil pressure rises to a level sufficient to overcome the force F1 of the right-side two-speed spring, it pushes the two-speed valve spool to the right, connecting port P and port A of the two-speed switching valve assembly. Simultaneously, the pilot oil acts on the third check valve, opening it and closing the first and second check valves. The pilot oil then flows through the third check valve and the two-speed switching valve assembly to the bottom of the variable displacement assembly's plunger, pushing it out and rotating the swash plate to the motor's low-displacement position.

[0086] The oil flows through the oil port A of the balance valve assembly, the oil port A1 of the balance valve assembly, and the oil port A of the travel motor into the working chamber of the travel motor. The pressure is P A At the same time, the oil in port A also pushes the balancing valve assembly to the right. The oil port A of the balancing valve assembly is also connected to the oil port P of the balancing valve assembly. The oil enters the working chamber of the brake assembly, overcomes the spring force of the brake assembly, and releases the mechanical brake of the motor.

[0087] The valve port between the oil port B of the travel motor and the oil return chamber of the travel motor is opened, and the oil return chamber of the travel motor is connected to the oil port B of the travel motor.

[0088] When the pressure on the oil port A side of the travel motor overcomes the motor load, the motor starts smoothly at high speed, avoiding shock and vibration caused by switching displacement during the starting process.

[0089] When the oil pressure P at port A of the travel motor A When the force acting on the first one-way valve and the third one-way valve is greater than the force acting on the pilot oil inlet plug, the first one-way valve opens and the third one-way valve closes, and the oil at the oil port P of the two-speed switching valve assembly enters the bottom of the variable assembly plunger through the two-speed switching valve assembly, so that the motor always maintains a high-speed state.

[0090] When the travel motor moves backward, oil enters the oil port B of the balancing valve assembly, the balancing valve assembly moves to the left, the oil port A of the balancing valve assembly is connected to the oil port A1, and the oil port B of the balancing valve assembly is connected to the oil port B1 and the oil port P. The working process is the same as the above method.

[0091] Furthermore, the effective area of ​​the annular gap damping The expression is as follows:

[0092] =

[0093] Wherein, D1 is the diameter of the first dual-speed valve core installation hole, and d2 is the diameter of the second section valve core.

[0094] Furthermore, the expression of the pilot oil effective area A1 is as follows:

[0095] A1=π / 4*d1 2

[0096] In the base, π is the ratio of the circumference of a circle to the diameter of a circle, and d1 is the diameter of the first valve core.

[0097] Furthermore, the oil effective area A2 at the oil port P of the two-speed switching valve assembly is expressed as follows:

[0098] A2=π / 4*(d1 2 -d2 2 )

[0099] Wherein, π is the ratio of circumference to pi, d1 is the diameter of the first section of the valve core, and d2 is the diameter of the second section of the valve core.

[0100] The present invention realizes automatic two-speed switching through the diameter difference of the outer surface of the two-speed valve core; increases the annular gap damping, slows down the opening speed of the two-speed switching valve assembly, slows down the extension speed of the variable assembly plunger, reduces the pressure impact when the motor switches from low speed to high speed, reduces the jitter problem of the travel motor when switching from low speed to high speed, and improves the comfort of motor operation.

[0101] A one-way valve combination is set between the oil port A, oil port P and Ps port of the two-speed switching valve assembly. When the travel motor starts at high speed, the oil at the Ps port passes through the one-way valve combination and reaches the bottom of the variable plunger, pushing the swash plate to the small displacement state, so that the motor starts smoothly in the small displacement state.

[0102] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A new type of travel motor dual-speed switching system, characterized by: include: A two-speed switching valve assembly, a throttle plug, a first one-way valve, a second one-way valve and a third one-way valve. The two-speed switching valve assembly, the throttle plug, the first one-way valve, the second one-way valve and the third one-way valve are integrated in the same valve body. The two-speed switching valve assembly includes a two-speed valve core, a two-speed spring, a pilot oil inlet plug and a plug. A valve cavity is provided in the valve body. The valve cavity is provided with a first two-speed valve core mounting hole, a second two-speed valve core mounting hole and a countersunk groove. The valve body is also provided with an oil port T connected to the valve cavity, an oil port A, a first oil port P, a second oil port P, a first pilot oil channel, a left-end control oil channel port and a right-end oil drain port. The first oil port P is connected to the valve via an oil circuit in the valve body. The first oil port P is connected with the valve cavity through the oil circuit in the valve body, the second oil port P is connected with the valve cavity through the oil circuit in the valve body, the second oil port P is connected with the second check valve, one end of the first pilot oil channel is provided with a third check valve, and the other end is connected with the valve cavity, the oil port T is connected with the valve cavity through the oil circuit in the valve body, the oil port T is provided with a throttling plug, the oil port A is connected with the valve cavity through the oil circuit in the valve body, the left end control oil channel port is connected with the valve cavity through the oil circuit in the valve body, and the right end oil drain port is connected with the valve cavity through the oil circuit in the valve body; a pilot oil inlet plug is provided at one end of the valve cavity, and a plug is provided at the other end of the valve cavity.

2. According to claim 1, a novel dual-speed switching system for travel motors is characterized in that: The dual-speed valve core comprises a first valve core, a second valve core, a third valve core, a fourth valve core and a fifth valve core, and the first valve core, the second valve core, the third valve core, the fourth valve core and the fifth valve core are connected in sequence.

3. A novel dual-speed switching system for travel motors according to claim 1 or 2, characterized in that: Also includes: Balance valve assembly, brake assembly, travel motor, variable assembly; the oil port A1 of the balance valve assembly is connected to the oil port A of the travel motor, and the oil port A1 of the balance valve assembly is also connected to the oil inlet of the first one-way valve, the oil port B1 of the balance valve assembly is connected to the oil port B of the travel motor, and the oil port B1 of the balance valve assembly is also connected to the oil inlet of the second one-way valve; the oil outlet of the first one-way valve and the oil outlet of the second one-way valve are both connected to the oil port P of the dual-speed switching valve assembly, the right control end of the dual-speed switching valve assembly is connected to the pilot oil circuit, and the pilot oil circuit is also connected to the oil inlet of the third one-way valve Then, the oil outlet of the third one-way valve is also connected to the oil port P of the dual-speed switching valve assembly; the oil port P of the balancing valve assembly is connected to the oil port of the brake assembly, the oil port P of the balancing valve assembly is also connected to the left control end of the dual-speed switching valve assembly, the clutch end of the brake assembly is connected to the brake end of the travel motor, the swash plate control end of the travel motor is connected to the output end of the variable assembly, the oil port of the variable assembly is connected to the oil port A of the dual-speed switching valve assembly, the oil port T of the dual-speed switching valve assembly is connected to the oil tank; the oil port T of the balancing valve assembly is connected to the oil tank; the oil overflow port of the travel motor is connected to the oil tank; The oil port A of the balancing valve assembly is also connected to the oil inlet of the fourth one-way valve, the oil outlet of the fourth one-way valve is connected to the left control end of the balancing valve assembly 1, and the oil port A of the balancing valve assembly is also connected to the left control end of the balancing valve assembly through an oil return circuit; the oil port B of the balancing valve assembly is also connected to the oil inlet of the fifth one-way valve, the oil outlet of the fifth one-way valve is connected to the right control end of the balancing valve assembly, and the oil port B of the balancing valve assembly is also connected to the right control end of the balancing valve assembly through an oil return circuit.

4. A novel dual-speed switching system for travel motors according to claim 3, characterized in that: The pilot oil circuit is also connected to the oil tank via an annular gap damping.

5. According to claim 3, the novel dual-speed switching system for travel motors is characterized in that: The oil port A1 of the balancing valve assembly is also connected to the oil port B1 of the balancing valve assembly through a first overflow valve.

6. The novel dual-speed switching system for travel motor according to claim 1 is characterized in that: The oil port B1 of the balancing valve assembly is also connected to the oil port A1 of the balancing valve assembly through a second overflow valve.

7. A working method of a novel dual-speed switching system for a travel motor according to any one of claims 1 to 6, characterized in that: Specifically include: When moving forward, the oil passes through the oil port A of the balance valve assembly, through the oil port A1 of the balance valve assembly, and the oil port A of the travel motor into the working chamber of the travel motor, and the pressure is P A At the same time, the oil in port A also pushes the balance valve assembly to move to the right. The oil port A of the balance valve assembly is also connected to the oil port P of the balance valve assembly. The oil enters the working chamber of the brake assembly, overcomes the spring force of the brake assembly, and releases the motor mechanical brake. The valve port between the oil port B of the travel motor and the oil return chamber of the travel motor is opened, and the oil return chamber of the travel motor is connected to the oil port B of the travel motor; The oil in port A1 of the balancing valve assembly also opens the first check valve port, and the oil acts on the dual-speed valve core through port P, and the second check valve and the third check valve are closed under the action of the spring force and the oil; The pilot oil inlet plug is cut off, the two-speed valve core is in the left position under the action of the force F1 of the two-speed spring, the oil port A of the two-speed switching valve assembly is connected with the oil port T, the oil of the variable assembly flows into the oil tank through the two-speed switching valve assembly and the throttle plug, the swash plate works at a large angle, and the travel motor is in a large displacement state; when the oil pressure at the oil port A of the travel motor overcomes the motor load, the travel motor realizes low-speed travel; Or, when the travel motor switches from low-speed travel to high-speed travel, the pilot oil inlet plug is connected to the external control pilot oil, and the pilot oil acts on the left side of the dual-speed valve core; When Ps*A1>P A *A2 +F1, where Ps is the pilot oil pressure, A1 is the pilot oil action area, A2 is the oil action area at the oil port P of the dual-speed switching valve assembly, P A is the oil pressure at the oil port P of the dual-speed switching valve assembly, and F1 is the force of the dual-speed spring of the dual-speed switching valve assembly during low-speed travel; The two-speed valve core moves to the right. During the movement, part of the pilot oil will leak to the T port through the annular gap damping. The two-speed switching valve group opens slowly and steadily. At the same time, the two-speed switching valve assembly is in the right position, and the oil port P of the two-speed switching valve assembly is connected to the oil port A. The oil at the oil port P of the dual-speed switching valve assembly passes through the smoothly opened dual-speed valve core and enters the bottom of the variable assembly, pushing the variable plunger to slowly extend. The variable plunger pushes the swash plate to rotate smoothly to the small displacement state, and the motor realizes high-speed travel; Or, when the load of the travel motor increases during high-speed driving, the oil pressure P A Increase; When Ps * A1<P A *When A2 + F2, F2 is the force of the dual-speed spring of the dual-speed switching valve group during high-speed travel; The dual-speed valve core is under the oil pressure P A The oil port A of the dual-speed switching valve assembly is connected to the oil port T, and the oil flows into the oil tank through the variable assembly, the dual-speed switching valve assembly and the throttle plug. The variable plunger slowly retracts into the housing under the action of the swash plate, and the swash plate rotates smoothly to the large displacement state; Alternatively, when the travel motor starts at high speed, the pilot oil inlet plug is connected to the external control pilot oil, and the pilot oil moves the two-speed valve core to the left. When the pilot oil pressure is increased to overcome the force F1 of the two-speed spring on the right, the two-speed valve core is pushed to the right, and the oil port P of the two-speed switching valve assembly is connected to the oil port A; at the same time, the pilot oil acts on the third one-way valve, the third one-way valve opens, and the first one-way valve and the second one-way valve are closed; the pilot oil enters the bottom of the plunger of the variable assembly through the third one-way valve and the two-speed switching valve assembly, pushing the variable plunger to extend, and pushing the swash plate to rotate to the motor small displacement state; The oil enters the working chamber of the travel motor through the oil port A of the balance valve assembly, the oil port A1 of the balance valve assembly, and the oil port A of the travel motor. The pressure is P A At the same time, the oil in port A also pushes the balance valve assembly to move to the right. The oil port A of the balance valve assembly is also connected to the oil port P of the balance valve assembly. The oil enters the working chamber of the brake assembly, overcomes the spring force of the brake assembly, and releases the motor mechanical brake. The valve port between the oil port B of the travel motor and the oil return chamber of the travel motor is opened, and the oil return chamber of the travel motor is connected to the oil port B of the travel motor; When the pressure on the oil port A side of the travel motor overcomes the motor load, the motor starts smoothly at high speed; When the oil pressure P at port A of the travel motor A When the force acting on the first check valve and the third check valve is greater than the force acting on the pilot oil inlet plug, the first check valve opens, the third check valve closes, and the oil at the oil port P of the dual-speed switching valve assembly enters the bottom of the variable component plunger through the dual-speed switching valve assembly, so that the motor always maintains a high-speed state; Alternatively, when the travel motor moves backward, oil enters the oil port B of the balancing valve assembly, the balancing valve assembly moves to the left, the oil port A of the balancing valve assembly is connected to the oil port A1, and the oil port B of the balancing valve assembly is connected to the oil port B1 and the oil port P. The working process is the same as the above method.

8. The working method according to claim 7, characterized in that: The effective area of ​​the annular gap damping The expression is as follows: = ； Wherein, D1 is the diameter of the first dual-speed valve core installation hole, and d2 is the diameter of the second section valve core.

9. The working method according to claim 7, characterized in that: The expression of pilot oil action area A1 is as follows: A1=π / 4*d1 2 ; In the base, π is the ratio of a circle to a circle, and d1 is the diameter of the first valve core.

10. The working method according to claim 7, characterized in that: The expression of the oil action area A2 at the oil port P of the two-speed switching valve assembly is as follows: A2=π / 4*(d1 2 -d2 2 ); Among them, π is the ratio of pi, d1 is the diameter of the first section of the valve core, and d2 is the diameter of the second section of the valve core.

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