WO2018188449A1 - 行走马达换挡阀、行走马达和工程机械 - Google Patents

行走马达换挡阀、行走马达和工程机械 Download PDF

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Publication number
WO2018188449A1
WO2018188449A1 PCT/CN2018/079068 CN2018079068W WO2018188449A1 WO 2018188449 A1 WO2018188449 A1 WO 2018188449A1 CN 2018079068 W CN2018079068 W CN 2018079068W WO 2018188449 A1 WO2018188449 A1 WO 2018188449A1
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WO
WIPO (PCT)
Prior art keywords
working
port
chamber
spool
working position
Prior art date
Application number
PCT/CN2018/079068
Other languages
English (en)
French (fr)
Inventor
赵斌
吴传玉
李扬
戴维•普鲁斯特
Original Assignee
徐工集团工程机械有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 徐工集团工程机械有限公司 filed Critical 徐工集团工程机械有限公司
Priority to KR1020207013037A priority Critical patent/KR102273877B1/ko
Priority to DE112018002268.4T priority patent/DE112018002268T5/de
Priority to JP2020517249A priority patent/JP7162659B2/ja
Publication of WO2018188449A1 publication Critical patent/WO2018188449A1/zh

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/002—Hydraulic systems to change the pump delivery
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/2058—Electric or electro-mechanical or mechanical control devices of vehicle sub-units
    • E02F9/2062—Control of propulsion units
    • E02F9/207—Control of propulsion units of the type electric propulsion units, e.g. electric motors or generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K99/00—Subject matter not provided for in other groups of this subclass
    • H02K99/20—Motors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/52—Pressure control characterised by the type of actuation
    • F15B2211/526—Pressure control characterised by the type of actuation electrically or electronically
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/665—Methods of control using electronic components
    • F15B2211/6658—Control using different modes, e.g. four-quadrant-operation, working mode and transportation mode
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7058—Rotary output members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/75—Control of speed of the output member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/76—Control of force or torque of the output member
    • F15B2211/763—Control of torque of the output member by means of a variable capacity motor, i.e. by a secondary control on the motor

Definitions

  • the present disclosure relates to the field of construction machinery, and in particular to a travel motor shift valve, a travel motor, and a construction machine.
  • Travel motors are widely used in construction machinery such as excavators to drive engineering machinery.
  • the traveling motor usually includes a motor and a swash plate control mechanism.
  • the swash plate control mechanism can adjust the rotation speed of the output shaft of the motor by controlling the swash plate angle of the motor, so that the traveling motor has a two-speed shifting function of high speed and low speed.
  • the output speed of the traveling motor in the low speed mode, the output speed of the traveling motor is lower, but the displacement is larger, and the same input power can output a larger torque; while in the high speed mode, the output speed of the traveling motor is higher, but the displacement is smaller, the same At input power, a smaller torque can be output.
  • the travel motor When excavators and other construction machinery are walking under heavy-duty conditions such as ramps, muddy swamps or towings, the travel motor is often required to provide a larger driving torque, that is, the traveling motor is required to operate in a low-speed mode, so that the traveling motor provides a larger
  • the torque prevents the phenomenon of walking or walking weakness, and when the running resistance becomes smaller, it is necessary to switch from the low speed mode to the high speed mode to improve the walking efficiency. Therefore, the traveling motor is required to be able to switch between the high speed mode and the low speed mode.
  • the travel motor In order to control the travel motor to automatically switch from the high speed mode to the low speed mode under heavy load conditions, the travel motor is usually equipped with a travel motor shift valve.
  • the traveling motor shift valve controls whether the traveling motor is switched from the high speed mode to the low speed mode by controlling whether high pressure oil is supplied to the swash plate control mechanism, thereby realizing the automatic shifting function of the traveling motor.
  • the travel motor shift valve of the prior art generally determines whether to pass the high pressure oil control to the swash plate control mechanism by detecting whether the actual pressure of the motor exceeds a certain preset value at a high speed state. Shifting, and because the maximum power provided by the prime mover (engine) of the construction machine is a constant value, the output torque of the traveling motor is proportional to the working pressure and displacement. Under the same working condition, after switching from high speed to low speed, the motor The input port pressure will be lower than the pressure before the shift, that is, lower than the preset value. At this time, the shift valve will automatically switch back to the high speed mode. Therefore, the traveling motor will repeatedly switch between high and low speed under heavy load conditions. This causes the construction machinery to vibrate under heavy load conditions, which not only affects the life and safety of the shift valve itself, the travel motor and the construction machinery as a whole, but also reduces the comfort of the product.
  • one technical problem to be solved by the present disclosure is to prevent the traveling motor from repeatedly switching at high and low speeds, and to reduce the vibration of the engineering machinery under heavy load conditions.
  • the first aspect of the present disclosure provides a travel motor shift valve including a spool, a first working port, a second working port, a third working port, an external oil control port, and a feedback oil.
  • the valve core has a first working position and a second working position. When the first working position is closed, the first working oil port is closed and the second working oil port is connected with the third working oil port.
  • a working oil port is connected to the third working oil port and the second working oil port is closed; the first working oil port is for communicating with the oil source, the second working oil port is for communicating with the oil tank, and the third working oil port is for communicating with the oil tank
  • the swash plate control mechanism of the traveling motor is connected; the external control oil port is used for guiding the control oil to act on the axial first end of the valve core and causing the spool to move from the first working position to the second working position, and the feedback oil port is used Returning the actual working pressure of the motor of the traveling motor to the axial second end of the spool and causing the spool to move from the second working position to the first working position, and the traveling motor shift valve is set to Make:
  • the spool When the oil pressure of the feedback port is less than the first preset value P C1 , the spool can be moved from the first working position to the second working position, and when the oil pressure of the feedback port is greater than the second preset value P C2 , the spool can Moving from the second working position to the first working position, wherein the first preset value P C1 is not equal to the second preset value P C2 ;
  • the oil pressure of the feedback port is the first working value P C3
  • the feedback port is The oil pressure is the second working value P C4 , wherein the first working value P C3 and the second preset value P C2 satisfy P C3 ⁇ K 1 P C2 , K 1 ⁇ 1, and the second working value P C4 and The first preset value P C1 satisfies P C4 >K 2 P C1 , and K 2 ⁇ 1.
  • the travel motor shift valve further includes a first chamber, a second chamber, and a third chamber, the first chamber is in communication with the external oil control port, the third chamber is in communication with the feedback oil port, and the second chamber is Communicating with the third working oil port and communicating with the second working oil port and the first working oil port during the movement of the valve core from the first working position to the second working position, and the effective pressure of the second working chamber The area is smaller than the effective pressure acting area of the third chamber.
  • the travel motor shift valve further includes a spring disposed at the axially second end of the spool and applying a force to the spool to cause the spool to move from the second working position to the first working position,
  • the first working value P C3 is The second working value is
  • P X is the oil pressure of the external control port
  • a 1 , A 2 and A 3 are the effective pressure acting areas of the first chamber, the second chamber and the third chamber, respectively
  • F 1 and F 2 are respectively springs.
  • the force applied to the spool at the first working position and the second working position, V 1 and V 2 are the displacements of the motor at the first working position and the second working position, respectively.
  • the second chamber and the third chamber are disposed on the spool and are respectively located at an axial first end and an axial second end of the spool.
  • the axial first end and the axial second end of the valve core are respectively provided with a first plunger chamber and a second plunger chamber, wherein the first plunger chamber is provided with a first plunger and a second plunger A second plunger is disposed in the chamber, the second chamber being located between the first plunger and the inner wall of the first plunger chamber, and the third chamber being located between the second plunger and the inner wall of the second plunger chamber.
  • a first passage is further disposed on the spool, and the second chamber is in communication with one of the first working port and the second working port through the first passage; and/or the second portion is further disposed on the spool
  • the passage, the third chamber is in communication with the feedback port through the second passage.
  • the travel motor shift valve further includes a first blocking member, the first blocking member is disposed at the axial second end of the valve core, and the spring of the travel motor shift valve is abutted against the first blocking member and the valve Between the axial second ends of the core and the application of a force to the spool to cause the spool to move from the second working position to the first working position.
  • a spring receiving cavity is disposed on a surface of the first blocking member near the valve core, and the spring is disposed in the spring receiving cavity.
  • the first blocking member is further provided with a first through hole, and the first through hole is in communication with the spring receiving cavity.
  • a fastening groove is provided on a surface of the first blocking member remote from the valve core.
  • the axial first end of the spool has a necked portion.
  • a groove is provided on the circumferential surface of the neck portion.
  • a second aspect of the present disclosure also provides a traveling motor including a motor and a swash plate control mechanism that is drivingly coupled to a swash plate of the motor, and further comprising a travel motor shift valve of the present disclosure, a travel motor shift valve setting Inside the housing of the motor.
  • a second through hole is disposed in the housing, and a spool of the travel motor shift valve is received in the second through hole, and the first working oil port and the second working oil port of the travel motor shift valve are The third working port, the outer control port and the feedback port are all disposed on the inner wall of the housing.
  • a third aspect of the present disclosure also provides a construction machine including the traveling motor of the present disclosure.
  • the present disclosure improves the travel motor shift valve such that the spool of the travel motor shift valve performs switching from low speed to high speed and high speed to low speed at two different preset values, respectively, and makes the shift after the shift
  • the motor input pressure value does not meet the shift boundary condition, which can effectively prevent the traveling motor from repeatedly switching at high and low speeds, and reduce the vibration of the engineering machinery under heavy load conditions.
  • FIG. 1 shows a hydraulic principle diagram of a travel motor system in accordance with an embodiment of the present disclosure.
  • Figure 2 is a cross-sectional view showing the travel motor shift valve spool of Figure 1 in a first working position.
  • Figure 3 is a cross-sectional view showing the travel motor shift valve spool of Figure 1 in a second working position.
  • Fig. 4 is a view showing the structure of the valve body of Figs. 2 and 3.
  • orientation words such as “front, back, up, down, left, right", “horizontal, vertical, vertical, horizontal” and “top, bottom”, etc. indicate the orientation.
  • positional relationship is generally based on the orientation or positional relationship shown in the drawings, and is merely for the convenience of the description of the disclosure and the simplification of the description, which does not indicate or imply the indicated device or component. It must be constructed and operated in a specific orientation or in a specific orientation, and thus is not to be construed as limiting the scope of the disclosure; the orientations “inside and outside” refer to the inside and outside of the contour of the components themselves.
  • Figures 1-4 illustrate one embodiment of the present disclosure.
  • the travel motor shift valve 100 provided by the present disclosure includes a spool 1, a first working port Y, a second working port L, a third working port Z, an external port X and feedback.
  • Port C the spool 1 has a first working position and a second working position. In the first working position, the first working port Y is closed and the second working port L is in communication with the third working port Z.
  • the first working port Y is in communication with the third working port Z and the second working port L is closed; the first working port Y is for communicating with the oil source, and the second working port L is for The fuel tank is connected, and the third working port Z is used for communicating with the swash plate control mechanism 500 of the traveling motor; the external oil control port X is for guiding the control oil to act on the axial first end of the valve body 1 and causing the valve body 1 to be produced.
  • the feedback port C is used to feed back the actual working pressure of the motor 400 of the traveling motor to the axial second end of the spool 1 and to cause the spool 1 to be generated by the second working position A tendency to move to the first working position, wherein the travel motor shift valve 100 is set such that:
  • the spool 1 When the oil pressure of the feedback port C is less than the first preset value P C1 , the spool 1 can be moved from the first working position to the second working position, and when the oil pressure of the feedback port C is greater than the second preset value P C2 , The spool 1 can be moved from the second working position to the first working position, wherein the first preset value P C1 is not equal to the second preset value P C2 ;
  • the oil pressure of the feedback port C is the first working value P C3
  • the spool 1 is switched from the second working position to the first working position
  • the feedback is The oil pressure of the port C is a second working value P C4 , wherein the first working value P C3 and the second preset value P C2 satisfy P C3 ⁇ K 1 P C2 , K 1 ⁇ 1, and the second work Between the value P C4 and the first preset value P C1 , P C4 >K 2 P C1 is satisfied, and K 2 ⁇ 1.
  • P C1 and P C2 are the critical pressure values of the motor 400 for controlling the travel motor from the low speed to the high speed and the high speed to the low speed, respectively, in the travel motor shift valve 100
  • P C3 and P C4 are respectively the motor 400
  • the travel motor shift valve 100 controls the actual input pressure value after the travel motor is switched from low speed to high speed and from high speed to low speed
  • K 1 and K 2 are respectively safe for the travel motor to be stable at high speed after switching from low speed to high speed.
  • the coefficient and the travel motor are switched from high speed to low speed and the safety factor is stable and low speed.
  • the present disclosure improves the travel motor shift valve 100 such that the spool 1 of the travel motor shift valve 100 controls the travel motor to switch from low speed to high speed and high speed to low speed at two different preset values, respectively. Moreover, the actual working pressure value of the motor 400 after the shifting does not satisfy the shifting boundary condition, and the shifting of the traveling motor at high and low speeds can be effectively prevented, and the vibration of the engineering machinery under heavy load conditions can be reduced, which is advantageous for extending the shifting valve of the traveling motor. 100, the service life of the travel motor and construction machinery, improve the safety of walking and improve the comfort of use.
  • K 1 ⁇ 1, and/or, K 2 >1 such that the traveling motor is stabilized in the post-switching speed state after switching from low speed to high speed and/or from high speed to low speed
  • the coefficient is higher, which can prevent the high and low speeds of the traveling motor from being repeatedly switched repeatedly, and more effectively reduce the vibration of the engineering machinery under heavy load conditions, thereby further prolonging the service life of the shifting valve 100, the traveling motor and the construction machinery of the traveling motor. Improve walking safety and improve comfort.
  • the travel motor shift valve 100 may further include a first chamber 1a, a second chamber 1b, and a third chamber 1c, the first chamber 1a and the external oil control
  • the port X is connected, the third chamber 1c is in communication with the feedback port C, and the second chamber 1b is in communication with the third working port Z and is switched during the movement of the spool 1 from the first working position to the second working position. It is in communication with the second working port L and the first working port Y, and the effective pressure acting area of the second chamber 1b is smaller than the effective pressure acting area of the third chamber 1c.
  • the present disclosure only needs to set the effective pressure acting area of the first chamber 1a, the second chamber 1b, and the third chamber 1c, so that the spool 1 of the traveling motor shift valve 100 can be respectively in two
  • the driving motor is controlled by a different preset value from low speed to high speed and from high speed to low speed, and the actual working pressure value of the motor 400 after shifting can not meet the shifting boundary condition, the structure is simple, and the cost is relatively low. Low and high reliability. This will be further illustrated in conjunction with the embodiment shown in Figures 1-4.
  • the traveling motor system includes a traveling motor, a traveling motor shift valve 100, a pressure selecting valve 300, a balancing valve 200, and the like, and the traveling motor includes a motor 400, a swash plate control mechanism 500, and the like.
  • the swash plate control mechanism 500 is drivingly connected to the swash plate of the motor 400 for changing the swing angle of the swash plate by driving the swash plate to swing.
  • the swash plate control mechanism 500 of this embodiment is specifically a hydraulic cylinder whose cylinder rod is connected to the swash plate.
  • the swash plate control mechanism 500 drives the swash plate to swing to a smaller angular position to switch the traveling motor to the low speed mode; and when the swash plate control mechanism 500 is free of the rod
  • the swash plate control mechanism 500 can drive the swash plate to swing to a larger angular position to switch the traveling motor to the high speed mode.
  • the motor 400 is connected to the port A and the port B through the balancing valve 200.
  • the drain of the motor 400 flows out through the other of the port A and the port B, so that the motor 400 can be driven to rotate clockwise or counterclockwise.
  • the travel motor shift valve 100 is used to control the rodless chamber switching of the swash plate control mechanism 500 to communicate with one of the oil source and the oil tank to control the walking by controlling whether oil is supplied to the rodless chamber of the swash plate control mechanism 500.
  • the motor switches between high speed mode and low speed mode.
  • the travel motor shift valve 100 communicates with the rodless chamber of the swash plate control mechanism 500 and communicates with the balance valve 200 through the pressure selection valve 300.
  • the pressure selection valve 300 is a shuttle valve; the first working port Y of the travel motor shift valve 100 is in communication with the outlet of the pressure selection valve 300, and the two inlets of the pressure selection valve 300 pass through the balancing valve 200 and the port A, respectively.
  • the second working port L of the traveling motor shift valve 100 is in communication with the oil tank; the third working port Z of the traveling motor shift valve 100 is in communication with the rodless chamber of the swash plate control mechanism 500.
  • the first working port Y can always be in communication with the larger one of the port A and the port B. Since the pressure value of the port A pressure and the port B pressure is the oil source pressure, and is also the input pressure of the motor 400 or the actual working pressure, the first working port Y is always with the oil source. It is connected and its pressure value P Y is substantially equal to the actual working pressure value of the motor 400.
  • the travel motor shift valve 100 In order to enable the travel motor shift valve 100 to control the rodless chamber switching of the swash plate control mechanism 500 to communicate with one of the oil source and the fuel tank, as shown in FIG. 1, the travel motor shift valve 100 has a first working position (Fig. The left position in 1) and the second working position (right position in Figure 1). It can be seen from FIG. 1 that when in the first working position, the first working oil port Y is closed and the second working oil port L is in communication with the third working oil port Z, which makes the traveling motor shift valve 100 communicate with the swash plate control.
  • the rodless cavity of the mechanism 500 and the oil tank so that the rodless cavity of the swash plate control mechanism 500 is released at this time, under the reaction force of the swash plate, the cylinder rod of the swash plate control mechanism 500 is retracted, and the swash plate is driven by FIG.
  • the vertical direction swings in the horizontal direction, increasing the swing angle of the swash plate to the maximum value, minimizing the output shaft speed of the motor 400, thereby operating the traveling motor in the low speed mode; and when in the second working position, The first working port Y is in communication with the third working port Z and the second working port L is closed, which causes the traveling motor shift valve 100 to communicate with the rodless cavity and the oil source of the swash plate control mechanism 500, thereby high pressure oil at this time.
  • the traveling motor shift valve 100 can enter the rodless cavity of the swash plate control mechanism 500, push the cylinder rod of the swash plate control mechanism 500 to extend, and drive the swash plate to swing in the vertical direction of FIG. 1 to reduce the swash plate.
  • the swing angle to the minimum value increases the output shaft speed of the motor 400 to the maximum Thereby enabling travel motor operates in high speed mode.
  • the first working position and the second working position of the spool 1 respectively correspond to the low speed mode (low speed working state, or first working state) and the high speed mode (high speed working state, or second working state) of the traveling motor.
  • the travel motor shift valve 100 further includes an external control port X and a feedback port C.
  • the external control port X is used as a pilot control port for introducing control oil to the travel motor shift valve 100, and the travel motor shift valve 100 is controlled to be switched from the first working position to the second working position.
  • the feedback port C is used to feed back the actual working pressure of the motor 400 to the spool 1, so that the traveling motor shift valve 100 switches between the first working position and the second working position according to the actual running load of the motor 400. In order to more accurately control the travel motor to complete the shift according to actual needs. As described above, since the pressures of the first working port Y and the feedback port C are actually the actual working pressure of the motor 400, the pressure P Y of the first working port Y and the pressure P of the feedback port C C is equal.
  • the travel motor shift valve realizes switching control from high speed to low speed and from low speed to high speed according to the same preset value.
  • the maximum input power of the traveling motor is a constant value
  • the output torque of the traveling motor is proportional to the working pressure and the displacement. Therefore, after switching from high speed to low speed, the motor input port pressure will be lower than the preset value.
  • the travel motor shift valve controls the travel motor to automatically switch back to the high speed mode, and after switching back to the high speed, the motor input port pressure rises to a preset value. Since the critical condition of switching from high speed to low speed is satisfied, the travel motor shift valve controls the travel motor to automatically switch back to the low speed mode, so that the travel motor cannot be maintained in the desired low speed mode. There will be repeated high and low speed switching, which will cause the construction machinery to vibrate, which not only affects the life and safety of the shift valve itself, the travel motor and the construction machinery as a whole, but also reduces the comfort of the product.
  • this embodiment improves the structure of the traveling motor shift valve 100. This will be described in detail below with reference to Figures 2-4.
  • the travel motor shift valve 100 is disposed inside the casing 5 of the motor 400, and includes a valve body 1, a first plunger 21, a second plunger 22, and a a blocking member 31, a second blocking member 32, a spring 4, a first working oil port Y, a second working oil port L, a third working oil port Z, an external oil control port X, a first chamber 1a, a second The chamber 1b and the third chamber 1c; and the travel motor shift valve 100 no longer includes the valve body, but the housing 5 as the valve body, and the spool 1 of the travel motor shift valve 100 is directly disposed in the housing 5, the first working port Y, the second working port L, the third working port Z, the outer control port X and the feedback port C of the travel motor shift valve 100 are both disposed on the inner wall of the housing 5. on.
  • the travel motor shift valve 100 and the motor 400 can be integrated into a single structure, which makes the structure more compact and reduces space occupation.
  • the casing 5 as the valve body, it is not necessary to separately provide a special valve body to accommodate the valve body 1 and the oil ports of the travel motor shift valve 100, and the structure can be further simplified, cost saving and convenient maintenance.
  • the housing 5 is provided with a second through hole 51, and the valve core 1 is received in the second through hole. 51.
  • the use of the second through hole 51 for accommodating the valve body 1 not only facilitates the processing, but also facilitates the disassembly and assembly of the valve body 1.
  • the second through hole 51 may be disposed on the back cover of the housing 5 (ie, the motor back cover).
  • the spool 1 is moved to realize switching between the first working position (right position in FIGS. 2-3) and the second working position (left position in FIG. 2-3) of the traveling motor shift valve 100 to control The on/off state of the first working port Y, the second working port L, and the third working port Z of the travel motor shift valve 100.
  • the spool 1 has an axial first end (in the figure, the right end) and an axial second end (in the drawing, the left end), and as shown in FIG.
  • the axial first end and the axial second end of the spool 1 are respectively provided with a first plunger chamber 1f and a second plunger chamber 1g.
  • the effective pressure acting area of the first plunger chamber 1f is smaller than the effective pressure acting area of the second plunger chamber 1g. It is not difficult to understand that the axial first end and the axial second end herein are not limited to the two end faces of the spool 1 in the axial direction, and may include one section respectively.
  • the first plunger 21 and the second plunger 22 are disposed in the first plunger chamber 1f and the second plunger chamber 1g, respectively.
  • a slidable sealing tape is formed between the first plunger 21 and the inner wall of the first plunger chamber 1f and between the second plunger 22 and the inner wall of the second plunger chamber 1g.
  • a sealed cavity is formed between the first plunger 21 and the inner wall of the first plunger chamber 1f and between the inner walls of the second plunger 22 and the second plunger chamber 1g, respectively.
  • the second chamber 1b and the third chamber 1c are respectively. That is, in this embodiment, the second chamber 1b and the third chamber 1c are disposed on the spool 1 and are respectively located at the axial first end and the axial second end of the spool 1.
  • the effective pressure acting area of the second chamber 1b is the effective pressure acting area of the first plunger chamber 1f
  • the effective pressure acting area of the third chamber 1c is the effective pressure acting area of the second plunger chamber 1g
  • the effective pressure acting area of the first plunger chamber 1f is smaller than the effective pressure acting area of the second plunger chamber 1g, and therefore, the effective pressure acting area of the second chamber 1b is smaller than the effective pressure acting area of the third chamber 1c.
  • the communication relationship between the second chamber 1b and the third chamber 1c and the oil ports is: the third chamber 1c is in communication with the feedback port C; The second chamber 1b is in communication with the third working port Z and is in communication with the second working port L and the first working port Y in the process of moving the spool 1 to the second working position, that is, The second chamber 1b communicates with the third working port Z and the second working port L when the spool 1 is in the first working position (as shown in FIG. 2) and when the spool 1 is in the second working position The three port Z is connected to the first working port Y (as shown in FIG. 3).
  • the valve body 1 is further provided with a first passage 1d, and a second The chamber 1b communicates with one of the first working port Y and the second working port L through the first passage 1d.
  • the second chamber 1b communicates with the second working oil port L through the first passage 1d; as shown in FIG. 3, in the second working position, the second chamber The chamber 1b communicates with the first working port Y through the first passage 1d.
  • the third chamber 1c and the feedback port C in this embodiment, as shown in FIG.
  • the valve body 1 is further provided with a second passage 1e, and the third chamber 1c is passed through the second The passage 1e is in communication with the feedback port C.
  • both the second chamber 1b and the third chamber 1c extend in the axial direction of the spool 1
  • the first passage 1d and the second passage 1e both extend in the radial direction of the spool 1.
  • the arrangement of the two chambers and the two channels on the valve core 1 is more reasonable and more compact, and the processing is more convenient.
  • the axial first end of the spool 1 further has a neck portion.
  • the circumferential surface of the neck portion is further provided with a groove 15. Since the groove 15 is more convenient to apply force to the neck portion, the groove 15 is provided to further reduce the difficulty in disassembling the valve body 1.
  • the axial first end and the axial second end of the valve body 1 are respectively provided with a second blocking member 32 and a first blocking member 31, wherein, the first blocking member 31 and the second blocking member 32 are connected to the housing 5 and respectively located on the axial second end side of the valve body 1 and the axial first end side of the valve body 1, respectively The axial end side of the valve body 1 and the axial first end side of the valve body 1 are sealed.
  • the first blocking member 31 is screwed into the second through hole 51 and located on the axial second end side of the valve body 1 for the second axial direction of the valve body 1. The end side is blocked.
  • the outer peripheral surface of the first blocking member 31 is provided with a thread
  • the inner wall of the corresponding portion of the second through hole 51 is also provided with a thread, so that the first blocking member 31 can be threaded by the cooperation of the thread. Connected to the second through hole 51.
  • the first blocking member 31 of this embodiment is further provided with a fastening groove 31b on the surface away from the valve body 1.
  • the fastening groove 31b is provided to facilitate the disassembly and assembly of the first blocking member 31.
  • the first blocking member 31 of this embodiment is screwed into the housing 5, and the action of the fastening groove 31b is more prominent. Because, based on the fastening groove 31b provided, the tool can be inserted into the fastening groove 31b when the first closure member 31 is attached and detached, and then to the inside of the second through hole 51 of the housing 5 or toward the second through hole.
  • the first sealing member 31 is screwed on the outer side of the 51, and the disassembly and assembly of the first blocking member 31 is realized, the operation is more convenient, and the disassembly and assembly efficiency is higher.
  • the first blocking member 31 of this embodiment is also used to support the spring 4.
  • the spring 4 is disposed between the first blocking member 31 and the axial second end of the valve body 1 for applying the valve core 1 to cause the spool 1 to move from the second working position to the first working position. force.
  • the surface of the first blocking member 31 near the valve body 1 is provided with a spring receiving cavity 31c, and the spring 4 is accommodated in The spring accommodating chamber 31c is disposed between the bottom wall of the spring accommodating chamber 31c and the axial second end of the valve body 1, so that the spring 4 can apply the valve body 1 to the spool 1 from the second working position The force of the first working position reset.
  • the axial second end of the valve body 1 further has a spring seat 16, and the spring 4 is connected to the valve body 1 by being sleeved on the spring seat 16, and the spring seat 16 and the valve core 1 are A shoulder is formed between adjacent segments, and the spring 4 abuts on the shoulder so that the spring 4 can be compressed or extended as the spool 1 moves between the first working position and the second working position. , changing the amount of elastic force applied to the spool 1.
  • the spring seat 16 defines a spring cavity between the first blocking member 31 and the inner wall of the second through hole 51.
  • the first blocking member 31 of this embodiment is further provided with a first through hole 31a communicating with the spring receiving chamber 31c. Based on this, it is not only easier to disassemble, but also easier to return oil. Specifically, the first through hole 31a extends along the axial direction of the valve body 1, so that the spring receiving cavity 31c can communicate with the outside based on the first through hole 31a of a smaller length, the structure is simpler, and the oil return is more convenient. .
  • the second blocking member 32 is screwed into the second through hole 51 and located on the axial first end side of the valve body 1 for the spool 1 The axial first end side is blocked.
  • the outer peripheral surface of the second blocking member 32 is provided with a thread
  • the inner wall of the corresponding portion of the second through hole 51 is also provided with a thread, so that the second blocking member 32 can be threaded by the cooperation of the thread. Connected to the second through hole 51.
  • first blocking member 31 and the second blocking member 32 are screwed to opposite sides of the second through hole 51 in the axial direction. With the screw connection, the first blocking member 31 and the second blocking member 32 have better sealing effect.
  • the first chamber 1a is located between the axial first end of the spool 1 and the second blocking member 32. Specifically, the first chamber 1a is located between the axial first end of the spool 1, the second blocking member 32, the first plunger 21, and the inner wall of the second through hole 51.
  • the first chamber 1a is in communication with the external oil control port X, such that the control oil introduced by the external oil control port X can enter the first chamber 1a and act on the axial first end of the valve body 1, so that the valve core 1 is produced by the first
  • the tendency of a working position to move to the second working position facilitates the switching of the spool 1 from the first working position to the second working position under the control of the external oil control port X.
  • a sealing ring 6 is further disposed between the second blocking member 32 and the housing 5, and the sealing ring 6 can achieve a tighter sealing of the first chamber 1a.
  • the first chamber 1a is located between the axial first end of the spool 1 and the second blocking member 32, and communicates with the external oil control port X; the second chamber 1b and the third chamber
  • the chamber 1c is located on the spool 1 and is respectively located at an axial first end and an axial second end of the spool 1, wherein the third chamber 1c communicates with the feedback port C, and the second chamber 1b and the third
  • the working port Z communicates and communicates with the second working port L and the first working port Y in sequence during the movement of the spool 1 from the first working position to the second working position.
  • the valve body 1 of this embodiment has four sealing sections in the axial direction, respectively, which are sequentially distributed along the first end from the axial end to the second end in the axial direction.
  • a sealing section 11, a second sealing section 12, a third sealing section 13 and a fourth sealing section 14, and the four sealing sections are slidably sealed with the inner wall of the second through hole 51.
  • the first sealing section 11 is located on the first chamber 1a and the second working oil of the second through hole 51.
  • the inner wall surface between the ports L is sealed to isolate the first chamber 1a from the second working port L, ensuring that the first chamber 1a is only in communication with the outer oil control port X; meanwhile, the second sealing portion 12 is The inner wall surface of the second through hole 51 between the second chamber 1b and the first working oil port Y is sealed, and the necking portion between the first sealing portion 11 and the second sealing portion 12 is opposite to the second passage
  • the inner wall surface of the hole 51 between the second chamber 1b and the second working oil port L is formed to avoid, so that the second chamber 1b communicates with the second working oil port L and is isolated from the first working oil port Y;
  • the third sealing section 13 seals the inner wall surface of the second through hole 51 between the first working port Y and the third chamber 1c, and between the third sealing section 13 and the fourth sealing section
  • the first sealing section 11 is still located in the first chamber 1a and the second working oil of the second through hole 51.
  • the inner wall surface between the ports L is sealed to isolate the first chamber 1a from the second working port L, ensuring that the first chamber 1a is only in communication with the outer oil control port X; but differently, the first sealing portion 11 Sealing the inner wall surface of the second through hole 51 between the second chamber 1b and the second working oil port L, and the necking section between the first sealing portion 11 and the second sealing portion 12
  • the inner wall surface of the second through hole 51 between the second chamber 1b and the first working oil port Y is formed to avoid, so that the second chamber 1b is changed to communicate with the first working port Y and with the second working port L is isolated; although the third sealing section 13 and the fourth sealing section 14 are moved to the left, the necking section between the third sealing section 13 and the fourth sealing section 14 is still located to the second through hole 51
  • the inner wall surface between the ports L is sealed to isolate the first chamber 1a from the second working port L, ensuring
  • the inner wall surface between the chambers 1c is sealed, and the fourth sealing section 14 still seals the inner wall surface of the second through hole 51 between the feedback port C and the spring chamber, so that the third chamber 1c remains It is isolated from the first working port Y and the spring chamber, and still only communicates with the feedback port C.
  • the first chamber 1a when the spool 1 is in the first working position, the first chamber 1a is in communication with the external oil control port X, the second chamber 1b and the second working port L and the third working port Z Connected and isolated from the first working port Y, the third chamber 1c is in communication with the feedback port C; and when the spool 1 is in the second working position, the first chamber 1a is in communication with the external port X, the second chamber The chamber 1b is in communication with the first working port Y and the third working port Z and is isolated from the second working port L, and the third chamber 1c is in communication with the feedback port C.
  • the pressures of the first working port Y, the second working port L, the third working port Z, the external control port X, and the feedback port C are defined as P Y , P L , P Z , respectively.
  • P X and P C and define the effective pressure acting areas of the first chamber 1a, the second chamber 1b, and the third chamber 1c as A 1 , A 2 , and A 3 , respectively, and the spring 4 is in the first work.
  • boundary condition 1 for short
  • P C1 (P X ⁇ A 1 - F 1 ) / A3 (3).
  • This P C1 is referred to as a first preset value. It can be seen that when the oil pressure of the feedback port C is less than the first preset value P C1 , the spool 1 can be moved from the first working position to the second working position.
  • the equation of the force balance state of the valve core 1 at this time can be obtained as follows:
  • boundary condition 2 for switching the traveling motor from the high speed mode to the low speed mode is as follows:
  • P C2 (P X ⁇ A 1 - F 2 ) / (A 3 - A 2 ) (6).
  • This P C2 is referred to as a second preset value. It can be seen that when the oil pressure of the feedback port C is greater than the second preset value P C2 , the spool 1 can be moved from the second working position to the first working position.
  • the embodiment sets the first preset value P C1 and the second preset value P C2 to be unequal, thereby based on the formula (3) With equation (6), the corresponding relationship between the areas A 1 , A 2 and A 3 of the three chambers can be obtained.
  • this embodiment also controls the motor after shifting by designing the areas A 1 , A 2 and A 3 of the three chambers on the basis of the displacement situation in the high and low speed modes of the traveling motor.
  • the actual working pressure value of 400 is such that the actual working pressure value of the motor 400 after switching from the low speed to the high speed does not satisfy the boundary condition 2, so that it can be stably maintained in the high speed mode as expected, and the actual operation of the motor 400 after switching from high speed to low speed.
  • the pressure value does not satisfy the boundary condition 1, so that it can be stably maintained in the low speed mode as expected, thereby more effectively preventing the high and low speed repeated switching phenomenon from occurring.
  • the oil pressure of the feedback port C (ie, the actual working pressure of the motor 400) is counted as the first.
  • the oil pressure of the feedback port C is calculated as The second working value is P C4 .
  • boundary condition 3 the boundary condition that the first working value P C3 satisfies
  • boundary condition 3 is:
  • Equations (10), (9), and (6) the corresponding relationship between the areas A 1 , A 2 , and A 3 of the three chambers can be determined.
  • the integrated boundary condition 1, the boundary condition 2, the boundary condition 3, and the boundary condition 4 can determine the effective pressure acting areas A 1 , A 2 of the first chamber 1a, the second chamber 1b, and the third chamber 1c.
  • the relationship between A and A 3 in other words, by designing the effective pressure acting areas A 1 , A 2 and A 3 , the traveling motor shift valve 100 can be stably maintained in the desired speed mode after controlling the shifting of the traveling motor. Instead of repeatedly switching, causing the whole machine to vibrate.
  • the effective pressure acting area A 1 and the second cavity of the first chamber 1a of the traveling motor shift valve 100 shown in FIGS. effective pressure chamber 1b of the effective pressure acting area a 2 and the third chamber 1c of the active area a 3 the design and verification, can effectively prevent the high-low speed travel motors repeatedly switch.
  • the workflow of the travel motor shift valve 100 can be as follows:
  • the traveling motor When the actual working pressure of the traveling motor is greater than P C1 , the external control oil cannot push the spool 1 to the left, and the traveling motor can only operate in the low speed mode; when the actual working pressure of the traveling motor is less than P C1 , the externally controlled oil pushes the spool 1 Move left, when left to the left and when the spool 1 is switched to the second working position (the travel motor switches to the high speed mode), the travel motor pressure will be lower than K 1 P C2 due to the boundary condition 3, since The boundary condition 2 is satisfied, so that the traveling motor can stably operate in the high speed mode; and when the actual working pressure of the traveling motor is greater than P C2 , the spool 1 is moved to the right by the interaction of the spring force and the respective closed chambers, by the boundary According to the limitation of condition 4, when switching to the low speed mode, the traveling motor pressure will be higher than K 2 P C1 , and since the boundary condition 1 is not satisfied, the traveling motor will be stably operated in the low speed mode.
  • the traveling motor shift valve 100 has the first chamber 1a, the second chamber 1b, and the third chamber 1c, and respectively pairs the first chamber 1a, the second chamber 1b, and the third chamber
  • the effective pressure acting areas A 1 , A 2 and A 3 of the chamber 1c are designed to control the traveling motor to be stably maintained in the corresponding working mode after shifting, without repeated switching repeatedly, thereby being effective Solving the problem of vibration of the whole machine is beneficial to prolonging the life of the travel motor shift valve 100, the traveling motor and even the construction machinery products, and improving the safety of the construction machinery.
  • the overall structure is relatively simple, the control is convenient, the control precision and the operational reliability are relatively high, and the cost is also low.
  • the second chamber 1b and the third chamber 1c may not be disposed on the spool 1, for example, may be disposed on the spool 1 and the housing 5 or a special valve body.
  • the second chamber 1b and the third chamber 1c are disposed on the valve core 1.
  • the utility model has the advantages that the structure of the travel motor shift valve 100 can be made simple and compact, and the oil path design is convenient, and Therefore, it is only necessary to design the structure of the spool 1 mainly, thereby reducing the risk of repeated switching between high and low speeds, and being simpler and more convenient.
  • the spool 1 shown in FIG. 4 has the same diameter of the four sealing sections, it should be understood that this does not constitute a limitation of the present disclosure, for example, the different sealing sections of the spool 1 are set to have different It is also possible to have a diameter, or to open some auxiliary holes in the casing 5 or the like.
  • the present disclosure also provides a travel motor and a construction machine.
  • the travel motor includes a motor 400 and a swash plate control mechanism 500 coupled to the swash plate of the motor 400, and further includes a travel motor shift valve 100 of the present disclosure, the travel motor shift valve 100 being disposed on the casing of the motor 400 Inside the body 5.
  • the construction machine includes the traveling motor of the present disclosure.
  • the construction machine of the present disclosure may be, for example, a crawler machine such as an excavator.

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Abstract

公开了一种行走马达换挡阀（100）、行走马达和工程机械。行走马达换挡阀（100）包括阀芯（1）、第一工作油口（Y）、第二工作油口（L）、第三工作油口（Z）、外控油口（X）和反馈油口（C）；阀芯（1）分别在两个不同的预设值下进行由低速至高速和由高速至低速的切换，并使得换挡后的马达（400）输入压力值均不满足换挡边界条件，可以有效防止行走马达高低速反复切换，减少工程机械重载工况下的颤动。

Description

行走马达换挡阀、行走马达和工程机械
相关申请
本公开是以申请号为201711246964.4，申请日为2017年12月1日的中国申请为基础，并主张其优先权，该中国申请的公开内容在此作为整体引入本申请中。
技术领域
本公开涉及工程机械技术领域，特别涉及一种行走马达换挡阀、行走马达和工程机械。
背景技术
行走马达被广泛应用于挖掘机等工程机械中，驱动工程机械行走。行走马达通常包括马达和斜盘控制机构，斜盘控制机构通过控制马达的斜盘角度可以调整马达的输出轴的转速，使行走马达具备高速和低速两级变速功能。其中，低速模式时，行走马达输出转速较低，但排量较大，同一输入功率下，可以输出较大的扭矩；而高速模式时，行走马达输出转速较高，但排量较小，同一输入功率下，可以输出较小的扭矩。
当挖掘机等工程机械行走在坡道、泥泞沼泽或拖曳等重载工况下时，往往要求行走马达提供更大的驱动力矩，即要求行走马达工作于低速模式，以使行走马达提供较大的扭矩，防止出现走不动或行走无力的现象，而当行走阻力变小后，又需要再由低速模式切换为高速模式，以提高行走效率。因此，要求行走马达能够在高速模式和低速模式下切换工作。
为了控制行走马达在重载工况下自动由高速模式切换为低速模式，通常为行走马达配备行走马达换挡阀。行走马达换挡阀通过控制是否向斜盘控制机构通入高压油，来控制行走马达是否由高速模式切换为低速模式，实现行走马达的自动换挡功能。
发明内容
然而，发明人认识到，现有技术中的行走马达换挡阀，其通常通过在高速状态下检测马达实际压力是否超过某一预设值，来判断是否向斜盘控制机构通入高压油控制换挡，而由于工程机械的原动机(发动机)所提供的最大功率为一恒定值，行走马达的输出扭矩与工作压力和排量成正比，同工况下，由高速切换至低速后，马达输入口 压力将低于换档前的压力，即低于预设值，此时换挡阀又会自动切换回高速模式，因此，造成行走马达在重载工况下出现高低速反复切换的现象，导致工程机械重载工况下发生颤动，不仅影响换挡阀本身、行走马达及工程机械整体的寿命与安全，同时也会降低产品的舒适性。
基于此，本公开所要解决的一个技术问题是：防止行走马达高低速反复切换，减少工程机械重载工况下的颤动。
为了解决上述技术问题，本公开第一方面提供了一种行走马达换挡阀，其包括阀芯、第一工作油口、第二工作油口、第三工作油口、外控油口和反馈油口，阀芯具有第一工作位和第二工作位，在第一工作位时，第一工作油口截止且第二工作油口与第三工作油口连通，在第二工作位时，第一工作油口与第三工作油口连通且第二工作油口截止；第一工作油口用于与油源连通，第二工作油口用于与油箱连通，第三工作油口用于与行走马达的斜盘控制机构连通；外控油口用于引导控制油作用于阀芯的轴向第一端并使阀芯产生由第一工作位向第二工作位移动的趋势，反馈油口用于将行走马达的马达的实际工作压力反馈至阀芯的轴向第二端并使阀芯产生由第二工作位向第一工作位移动的趋势，并且，该行走马达换挡阀被设置为使得：
反馈油口的油压小于第一预设值P C1时，阀芯能够由第一工作位移动至第二工作位，反馈油口的油压大于第二预设值P C2时，阀芯能够由第二工作位移动至第一工作位，其中，第一预设值P C1与第二预设值P C2不相等；
并且，阀芯由第一工作位移动至第二工作位后，反馈油口的油压为第一工作值P C3，阀芯由第二工作位切换至第一工作位后，反馈油口的油压为第二工作值P C4，其中，第一工作值P C3与第二预设值P C2之间满足P C3＜K 1P C2，K 1≤1，且第二工作值P C4与第一预设值P C1之间满足P C4＞K 2P C1，K 2≥1。
可选地，行走马达换挡阀还包括第一腔室、第二腔室和第三腔室，第一腔室与外控油口连通，第三腔室与反馈油口连通，第二腔室与第三工作油口连通并在阀芯由第一工作位向第二工作位移动的过程中切换地与第二工作油口和第一工作油口连通，且第二腔室的有效压力作用面积小于第三腔室的有效压力作用面积。
可选地，行走马达换挡阀还包括弹簧，弹簧设置于阀芯的轴向第二端并对阀芯施加使阀芯产生由第二工作位向第一工作位移动趋势的作用力，第一预设值P C1为P C1＝(P X×A 1-F 1)/A 3，第二预设值P C2为P C2＝(P X×A 1-F 2)/(A 3-A 2)，第一工作值P C3 为
Figure PCTCN2018079068-appb-000001
第二工作值为
Figure PCTCN2018079068-appb-000002
其中，P X为外控油口的油压，A 1、A 2和A 3分别为第一腔室、第二腔室和第三腔室的有效压力作用面积，F 1和F 2分别为弹簧在第一工作位和第二工作位对阀芯施加的作用力，V 1和V 2分别为马达在第一工作位和第二工作位时的排量。
可选地，第二腔室和第三腔室设置于阀芯上并分别位于阀芯的轴向第一端和轴向第二端。
可选地，阀芯的轴向第一端和轴向第二端分别设有第一柱塞腔和第二柱塞腔，第一柱塞腔中设有第一柱塞，第二柱塞腔中设有第二柱塞，第二腔室位于第一柱塞与第一柱塞腔的内壁之间，第三腔室位于第二柱塞与第二柱塞腔的内壁之间。
可选地，阀芯上还设有第一通道，第二腔室通过第一通道与第一工作油口和第二工作油口中的一个连通；和/或，阀芯上还设有第二通道，第三腔室通过第二通道与反馈油口连通。
可选地，行走马达换挡阀还包括第一封堵件，第一封堵件设置于阀芯的轴向第二端，行走马达换挡阀的弹簧抵设于第一封堵件与阀芯的轴向第二端之间并对阀芯施加使阀芯产生由第二工作位向第一工作位移动趋势的作用力。
可选地，第一封堵件的靠近阀芯的表面上设有弹簧容纳腔，弹簧设置于弹簧容纳腔中。
可选地，第一封堵件上还设有第一通孔，第一通孔与弹簧容纳腔连通。
可选地，第一封堵件的远离阀芯的表面上设有紧固槽。
可选地，阀芯的轴向第一端具有颈缩部。
可选地，颈缩部的周向表面上设有凹槽。
本公开第二方面还提供了一种行走马达，其包括马达和与马达的斜盘驱动连接的斜盘控制机构，并且，其还包括本公开的行走马达换挡阀，行走马达换挡阀设置于马达的壳体内部。
可选地，壳体上设有第二通孔，行走马达换挡阀的阀芯容置于第二通孔中，且行走马达换挡阀的第一工作油口、第二工作油口、第三工作油口、外控油口和反馈油口均设置于壳体的内壁上。
本公开第三方面还提供了一种工程机械，其包括本公开的行走马达。
本公开通过对行走马达换挡阀进行改进，使得行走马达换挡阀的阀芯分别在两个 不同的预设值下进行由低速至高速和由高速至低速的切换，并使得换挡后的马达输入压力值均不满足换挡边界条件，可以有效防止行走马达高低速反复切换，减少工程机械重载工况下的颤动。
通过以下参照附图对本公开的示例性实施例进行详细描述，本公开的其它特征及其优点将会变得清楚。
附图说明
为了更清楚地说明本公开实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本公开的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。
图1示出本公开一实施例的行走马达系统的液压原理图。
图2示出图1中行走马达换挡阀阀芯处于第一工作位时的剖视图。
图3示出图1中行走马达换挡阀阀芯处于第二工作位时的剖视图。
图4示出图2和图3中阀芯的结构示意图。
具体实施方式
下面将结合本公开实施例中的附图，对本公开实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本公开一部分实施例，而不是全部的实施例。以下对至少一个示例性实施例的描述实际上仅仅是说明性的，决不作为对本公开及其应用或使用的任何限制。基于本公开中的实施例，本领域普通技术人员在没有开展创造性劳动前提下所获得的所有其他实施例，都属于本公开保护的范围。
对于相关领域普通技术人员已知的技术、方法和设备可能不作详细讨论，但在适当情况下，所述技术、方法和设备应当被视为授权说明书的一部分。
在本公开的描述中，需要理解的是，方位词如“前、后、上、下、左、右”、“横向、竖向、垂直、水平”和“顶、底”等所指示的方位或位置关系通常是基于附图所示的方位或位置关系，仅是为了便于描述本公开和简化描述，在未作相反说明的情况下，这些方位词并不指示和暗示所指的装置或元件必须具有特定的方位或者以特定的方位构造和操作，因此不能理解为对本公开保护范围的限制；方位词“内、外”是指相对于各部件本身的轮廓的内外。
在本公开的描述中，需要理解的是，使用“第一”、“第二”等词语来限定零部件，仅仅是为了便于对相应零部件进行区别，如没有另行声明，上述词语并没有特殊含义，因此不能理解为对本公开保护范围的限制。
图1-4示出了本公开的一个实施例。参照图1-4，本公开所提供的行走马达换挡阀100，包括阀芯1、第一工作油口Y、第二工作油口L、第三工作油口Z、外控油口X和反馈油口C，阀芯1具有第一工作位和第二工作位，在第一工作位时，第一工作油口Y截止且第二工作油口L与第三工作油口Z连通，在第二工作位时，第一工作油口Y与第三工作油口Z连通且第二工作油口L截止；第一工作油口Y用于与油源连通，第二工作油口L用于与油箱连通，第三工作油口Z用于与行走马达的斜盘控制机构500连通；外控油口X用于引导控制油作用于阀芯1的轴向第一端并使阀芯1产生由第一工作位向第二工作位移动的趋势，反馈油口C用于将行走马达的马达400的实际工作压力反馈至阀芯1的轴向第二端并使阀芯1产生由第二工作位向第一工作位移动的趋势，其中，行走马达换挡阀100被设置为使得：
反馈油口C的油压小于第一预设值P C1时，阀芯1能够由第一工作位移动至第二工作位，反馈油口C的油压大于第二预设值P C2时，阀芯1能够由第二工作位移动至第一工作位，其中，第一预设值P C1与第二预设值P C2不相等；
并且，阀芯1由第一工作位移动至第二工作位后，反馈油口C的油压为第一工作值P C3，阀芯1由第二工作位切换至第一工作位后，反馈油口C的油压为第二工作值P C4，其中，第一工作值P C3与第二预设值P C2之间满足P C3＜K 1P C2，K 1≤1，且第二工作值P C4与第一预设值P C1之间满足P C4＞K 2P C1，K 2≥1。
在本公开中，P C1和P C2分别为马达400在行走马达换挡阀100控制行走马达由低速切换至高速和由高速切换至低速的临界压力值，P C3和P C4分别为马达400在行走马达换挡阀100控制行走马达由低速切换至高速和由高速切换至低速后的实际输入压力值，K 1和K 2则分别为行走马达由低速切换至高速后稳定于高速状态下的安全系数和行走马达由高速切换至低速后稳定与低速状态下的安全系数。
本公开通过对行走马达换挡阀100进行改进，使得行走马达换挡阀100的阀芯1分别在两个不同的预设值下控制行走马达进行由低速至高速和由高速至低速的切换，并使得换挡后马达400的实际工作压力值均不满足换挡边界条件，可以有效防止行走马达高低速反复切换，减少工程机械重载工况下的颤动，这有利于延长行走马达换挡阀100、行走马达及工程机械的使用寿命，提高行走安全性，改善使用舒适性。
在本公开中，优选地，K 1＜1，和/或，K 2＞1，这样行走马达在由低速切换至高速后和/或由高速切换至低速后稳定于切换后速度状态下的安全系数更高，可以更可靠地防止行走马达高低速反复切换，更有效地减少工程机械重载工况下的颤动，从而更有利于延长行走马达换挡阀100、行走马达及工程机械的使用寿命，提高行走安全性，改善使用舒适性。
作为本公开行走马达换挡阀100的一种实施方式，行走马达换挡阀100可以还包括第一腔室1a、第二腔室1b和第三腔室1c，第一腔室1a与外控油口X连通，第三腔室1c与反馈油口C连通，第二腔室1b与第三工作油口Z连通并在阀芯1由第一工作位向第二工作位移动的过程中切换地与第二工作油口L和第一工作油口Y连通，且第二腔室1b的有效压力作用面积小于第三腔室1c的有效压力作用面积。基于此，本公开只需对第一腔室1a、第二腔室1b和第三腔室1c的有效压力作用面积进行设置，即可使得行走马达换挡阀100的阀芯1能够分别在两个不同的预设值下控制行走马达进行由低速至高速和由高速至低速的切换，并使得换挡后马达400的实际工作压力值均能够不满足换挡边界条件，结构较简单，成本较低，且可靠性较高。这一点将结合图1-4所示的实施例予以进一步说明。
下面结合图1-4来对本公开予以进一步地说明。
为了便于理解，首先结合图1对行走马达系统的结构及工作原理进行说明。
如图1所示，行走马达系统包括行走马达、行走马达换挡阀100、压力选择阀300和平衡阀200等，行走马达包括马达400和斜盘控制机构500等。
其中，斜盘控制机构500与马达400的斜盘驱动连接，用于通过带动斜盘摆动来改变斜盘的摆角。由图1可知，该实施例的斜盘控制机构500具体为液压缸，其缸杆与斜盘连接。基于此，当斜盘控制机构500的无杆腔进油时，斜盘控制机构500驱动斜盘摆动至较小角度位置，使行走马达向低速模式切换；而当斜盘控制机构500的无杆腔中的油向油箱回流时，则斜盘控制机构500可以驱动斜盘摆动至较大角度位置，使行走马达向高速模式切换。
马达400通过平衡阀200与油口A和油口B连接。当油口A和油口B中的一个向马达400供油时，马达400的排油经油口A和油口B中的另一个流出，从而可以驱动马达400顺时针或逆时针转动。
行走马达换挡阀100用于控制斜盘控制机构500的无杆腔切换地与油源和油箱中的一个连通，以通过控制是否向斜盘控制机构500的无杆腔中供油来控制行走马达在 高速模式和低速模式之间切换。如图1所示，在该实施例中，行走马达换挡阀100与斜盘控制机构500的无杆腔连通并通过压力选择阀300与平衡阀200连通。具体地，压力选择阀300为梭阀；行走马达换挡阀100的第一工作油口Y与压力选择阀300的出口连通，压力选择阀300的两个进口分别通过平衡阀200与油口A和油口B连接；行走马达换挡阀100的第二工作油口L与油箱连通；行走马达换挡阀100的第三工作油口Z与斜盘控制机构500的无杆腔连通。
通过设置压力选择阀300，使得第一工作油口Y始终能与油口A和油口B中压力较大的一个连通。而由于油口A压力和油口B压力中较大的压力值即为油源压力，同时也即为马达400的输入压力或称实际工作压力，因此，第一工作油口Y始终与油源连通，且其压力值P Y实际上等于马达400的实际工作压力值。
为了使行走马达换挡阀100能够控制斜盘控制机构500的无杆腔切换地与油源和油箱中的一个连通，如图1所示，行走马达换挡阀100具有第一工作位(图1中的左位)和第二工作位(图1中的右位)。其中，由图1可知，当处于第一工作位时，第一工作油口Y截止且第二工作油口L与第三工作油口Z连通，这使得行走马达换挡阀100连通斜盘控制机构500的无杆腔与油箱，从而此时斜盘控制机构500的无杆腔泄压，在斜盘的反作用力下，斜盘控制机构500的缸杆回缩，带动斜盘由图1中的竖直方向朝水平方向摆动，增大斜盘的摆角至最大值，将马达400的输出轴转速降至最低，进而使行走马达工作于低速模式下；而当处于第二工作位时，第一工作油口Y与第三工作油口Z连通且第二工作油口L截止，这使得行走马达换挡阀100连通斜盘控制机构500的无杆腔与油源，从而此时高压油可以经由该行走马达换挡阀100进入斜盘控制机构500的无杆腔，推动斜盘控制机构500的缸杆外伸，驱动斜盘向图1中的竖直方向摆动，减小斜盘的摆角至最小值，使马达400的输出轴转速升高至最大，进而使行走马达工作于高速模式下。可见，阀芯1的第一工作位和第二工作位分别对应行走马达的低速模式(低速工作状态，或称第一工作状态)和高速模式(高速工作状态，或者第二工作状态)。
另外，由图1可知，行走马达换挡阀100还包括外控油口X和反馈油口C。其中，外控油口X用作先导控制油口，用于向行走马达换挡阀100引入控制油，控制行走马达换挡阀100由第一工作位向第二工作位切换。反馈油口C则用于将马达400的实际工作压力反馈至阀芯1上，以便于行走马达换挡阀100根据马达400的实际行走负载来在第一工作位和第二工作位之间切换，从而更准确地控制行走马达按照实际需求完 成换挡。如前所述，由于第一工作油口Y和反馈油口C的压力实际上均为马达400的实际工作压力，因此，第一工作油口Y的压力P Y与反馈油口C的压力P C相等。
现有技术中，行走马达换挡阀控制行走马达换挡的临界条件只有一个，即，马达工作压力达到预设值，也即，反馈油口C的压力P C等于预设值，这意味着现有技术中行走马达换挡阀根据同一预设值来实现对由高速向低速以及由低速向高速的切换控制。其问题在于，由于行走马达的最大输入功率为一恒定值，行走马达的输出扭矩与工作压力和排量成正比，因此，由高速切换至低速后，马达输入口压力将低于预设值，此时由于满足了由低速切换至高速的临界条件，因此，行走马达换挡阀又会控制行走马达自动切换回高速模式，而切换回高速后，马达输入口压力升高至预设值，此时由于又满足了由高速切换至低速的临界条件，因此，行走马达换挡阀又会控制行走马达自动切换回低速模式，如此反复，以致于行走马达无法保持于所期望的低速模式下，而是会出现高低速反复切换的现象，这会引起工程机械发生颤动，不仅影响换挡阀本身、行走马达及工程机械整体的寿命与安全，同时也会降低产品的舒适性。
为了解决现有技术中行走马达高低速反复切换的问题，该实施例对行走马达换挡阀100的结构进行了改进。下面结合图2-4予以详细说明。
如图2-3所示，在该实施例中，行走马达换挡阀100设置于马达400的壳体5的内部，其包括阀芯1、第一柱塞21、第二柱塞22、第一封堵件31、第二封堵件32、弹簧4、第一工作油口Y、第二工作油口L、第三工作油口Z、外控油口X、第一腔室1a、第二腔室1b和第三腔室1c；并且，该行走马达换挡阀100不再包括阀体，而是以壳体5作为阀体，行走马达换挡阀100的阀芯1直接设置于壳体5中，而行走马达换挡阀100的第一工作油口Y、第二工作油口L、第三工作油口Z、外控油口X和反馈油口C则均设置于壳体5的内壁上。
通过将行走马达换挡阀100设置于壳体5的内部，可以将行走马达换挡阀100与马达400集成为一体结构，使结构更加紧凑，减少空间占用。而利用壳体5作为阀体，使得无需再单独设置专门的阀体来容纳阀芯1及设置行走马达换挡阀100的各油口，还可以进一步简化结构，节约成本，方便维护。
具体地，由图3可知，为了方便阀芯1在壳体5中的设置，在该实施例中，壳体5上设有第二通孔51，阀芯1容置于该第二通孔51中。利用第二通孔51容置阀芯1，不仅加工方便，同时也便于阀芯1的拆装。其中，第二通孔51可以设置于壳体5的后盖上(即马达后盖上)。
阀芯1通过移动来实现行走马达换挡阀100在第一工作位(图2-3中的右位)和第二工作位(图2-3中的左位)之间的切换，以控制行走马达换挡阀100的第一工作油口Y、第二工作油口L和第三工作油口Z等的通断状态。如图3所示，在该实施例中，阀芯1具有轴向第一端(在图中即为右端)和轴向第二端(在图中即为左端)，且如图4所示，阀芯1的轴向第一端和轴向第二端分别设有第一柱塞腔1f和第二柱塞腔1g。第一柱塞腔1f的有效压力作用面积小于第二柱塞腔1g的有效压力作用面积。不难理解，此处的轴向第一端和轴向第二端不限于阀芯1轴向的两个端面，而可以分别包括一个区段。
如图2和图3所示，在该实施例中，第一柱塞21和第二柱塞22分别设置于第一柱塞腔1f和第二柱塞腔1g中。第一柱塞21与第一柱塞腔1f的内壁之间以及第二柱塞22与第二柱塞腔1g的内壁之间形成可自由滑动的密封带。在阀芯1由第一工作位切换至第二工作位的过程中，第一柱塞21相对于第一柱塞腔1f伸出且第二柱塞22相对于第二柱塞腔1g缩回；而在阀芯1由第二工作位切换至第一工作位的过程中，第一柱塞21相对于第一柱塞腔1f缩回且第二柱塞22相对于第二柱塞腔1g伸出。
基于上述设置，由图2和图3可知，第一柱塞21与第一柱塞腔1f的内壁之间以及第二柱塞22与第二柱塞腔1g的内壁之间分别形成密封腔，分别为第二腔室1b和第三腔室1c。即，在该实施例中，第二腔室1b和第三腔室1c设置于阀芯1上并分别位于阀芯1的轴向第一端和轴向第二端。由于第二腔室1b的有效压力作用面积即为第一柱塞腔1f的有效压力作用面积，第三腔室1c的有效压力作用面积即为第二柱塞腔1g的有效压力作用面积，且第一柱塞腔1f的有效压力作用面积小于第二柱塞腔1g的有效压力作用面积，因此，第二腔室1b的有效压力作用面积小于第三腔室1c的有效压力作用面积。
而且，如图2和图3所示，在该实施例中，第二腔室1b和第三腔室1c与各油口的连通关系为：第三腔室1c与反馈油口C连通；第二腔室1b与第三工作油口Z连通并在阀芯1在第一工作位向第二工作位移动的过程中先后与第二工作油口L和第一工作油口Y连通，即，第二腔室1b在阀芯1处于第一工作位时与第三工作油口Z和第二工作油口L连通(如图2所示)并在阀芯1处于第二工作位时与第三油口Z和第一工作口Y连通(如图3所示)。
而为了方便第二腔室1b与第二工作油口L或第一工作油口Y连通，如图4所示，在该实施例中，阀芯1上还设有第一通道1d，第二腔室1b通过第一通道1d与第一工 作油口Y和第二工作油口L中的一个连通。其中，如图2所示，在第一工作位时，第二腔室1b通过第一通道1d与第二工作油口L连通；如图3所示，在第二工作位时，第二腔室1b通过第一通道1d与第一工作油口Y连通。类似地，为了方便第三腔室1c与反馈油口C的连通，在该实施例中，如图4所示，阀芯1上还设有第二通道1e，第三腔室1c通过第二通道1e与反馈油口C连通。具体地，由图4可知，第二腔室1b和第三腔室1c均沿阀芯1的轴向延伸，而第一通道1d和第二通道1e则均沿阀芯1的径向延伸，这样两个腔室及两个通道在阀芯1上的布置更加合理紧凑，加工也更加方便。
并且，如图4所示，在该实施例中，阀芯1的轴向第一端还具有颈缩部。这样，在需要对阀芯1进行拆卸时，便于工作人员或者拆卸工具伸入第二通孔51中对阀芯1进行施力，使得阀芯1更容易从第二通孔51中取出，从而更便于阀芯1的拆卸。而且，由图4可知，颈缩部的周向表面上还进一步设有凹槽15。由于该凹槽15更便于对颈缩部施力，因此，设置凹槽15，可以进一步降低阀芯1的拆卸难度。
另外，如图2和图3所示，在该实施例中，阀芯1的轴向第一端和轴向第二端还分别设有第二封堵件32和第一封堵件31，其中，第一封堵件31和第二封堵件32连接于壳体5上并分别位于阀芯1的轴向第二端一侧和阀芯1的轴向第一端一侧，分别用于对阀芯1的轴向第二端一侧和阀芯1的轴向第一端一侧进行封堵。
其中，由图2和图3可知，第一封堵件31螺纹连接于第二通孔51中并位于阀芯1的轴向第二端一侧，用于对阀芯1的轴向第二端一侧进行封堵。具体地，第一封堵件31的外周表面上均设有螺纹，第二通孔51的对应部位的内壁上也设有螺纹，从而在螺纹的配合作用下，第一封堵件31可以螺纹连接于第二通孔51中。
并且，由图2和图3可知，该实施例的第一封堵件31，其远离阀芯1的表面上还设有紧固槽31b。设置紧固槽31b，便于第一封堵件31的拆装。尤其该实施例的第一封堵件31螺纹连接于壳体5内，紧固槽31b的作用更加突出。因为，基于所设置的紧固槽31b，在拆装第一封堵件31时，可以将工具插入紧固槽31b中，然后向壳体5的第二通孔51内侧或朝第二通孔51外侧旋拧第一封堵件31，实现第一封堵件31的拆装，操作更方便，拆装效率更高。
另外，该实施例的第一封堵件31还用于支承弹簧4。弹簧4抵设于第一封堵件31与阀芯1的轴向第二端之间，用于对阀芯1施加使阀芯1产生由第二工作位向第一工作位移动趋势的作用力。具体地，为了方便弹簧4的设置，如图2和图3所示，在 该实施例中，第一封堵件31的靠近阀芯1的表面上设有弹簧容纳腔31c，弹簧4容纳于该弹簧容纳腔31c中，并抵设于弹簧容纳腔31c的底壁与阀芯1的轴向第二端之间，这样弹簧4能够对阀芯1施加使阀芯1由第二工作位向第一工作位复位的作用力。并且，结合图2-4可知，阀芯1的轴向第二端还具有弹簧座16，弹簧4通过套设于弹簧座16上而与阀芯1连接，且弹簧座16与阀芯1的相邻区段之间形成轴肩，弹簧4抵设于轴肩上，从而当阀芯1在第一工作位和第二工作位之间移动的过程中，弹簧4可以随之压缩或伸长，改变对阀芯1所施加的弹性力大小。同时，容易理解，弹簧座16与第一封堵件31及第二通孔51的内壁之间限定形成弹簧腔。
而且，如图2和图3所示，该实施例的第一封堵件31，其上还设有第一通孔31a，该第一通孔31a与弹簧容纳腔31c连通。基于此，不仅更便于拆卸，同时也更便于回油。具体地，第一通孔31a沿着阀芯1的轴向延伸，这样基于较小长度的第一通孔31a，即可实现弹簧容纳腔31c与外部的连通，结构更简单，回油更方便。
如图2和图3所示，在该实施例中，第二封堵件32螺纹连接于第二通孔51中并位于阀芯1的轴向第一端一侧，用于对阀芯1的轴向第一端一侧进行封堵。具体地，第二封堵件32的外周表面上设有螺纹，第二通孔51的对应部位的内壁上也均设有螺纹，从而在螺纹的配合作用下，第二封堵件32可以螺纹连接于第二通孔51中。
可见，在该实施例中，第一封堵件31和第二封堵件32螺纹连接于第二通孔51轴向的相对两侧。采用螺纹连接方式，第一封堵件31和第二封堵件32的封堵效果更好。
另外，如图2和图3所示，在该实施例中，第一腔室1a位于阀芯1的轴向第一端与第二封堵件32之间。具体地，第一腔室1a位于阀芯1的轴向第一端、第二封堵件32、第一柱塞21及第二通孔51的内壁之间。第一腔室1a与外控油口X连通，这样外控油口X引入的控制油能够进入第一腔室1a中，并作用于阀芯1的轴向第一端，使阀芯1产生由第一工作位向第二工作位移动的趋势，便于阀芯1在外控油口X的控制作用下由第一工作位切换至第二工作位。其中，为了进一步改善密封效果，如图2所示，第二封堵件32与壳体5之间还设有密封圈6，该密封圈6可以实现对第一腔室1a更严密地密封。
综合以上可知，在该实施例中，第一腔室1a位于阀芯1的轴向第一端与第二封堵件32之间，与外控油口X连通；第二腔室1b和第三腔室1c位于阀芯1上并分别位于阀芯1的轴向第一端和轴向第二端，其中，第三腔室1c与反馈油口C连通，而 第二腔室1b与第三工作油口Z连通并在阀芯1在第一工作位向第二工作位移动的过程中先后与第二工作油口L和第一工作油口Y连通。
具体地，由图2-4可知，该实施例的阀芯1，其沿轴向依次具有四个密封区段，分别为沿着由轴向第一端至轴向第二端依次分布的第一密封区段11、第二密封区段12、第三密封区段13和第四密封区段14，且这四个密封区段与第二通孔51的内壁滑动密封。相邻的密封区段之间具有颈缩段。这样，阀芯1在第一工作位和第二工作位之间移动的过程中能够通过这四个密封区段来控制第一腔室1a、第二腔室1b和第三腔室1c与各油口的连通关系。
其中，如图2所示，当阀芯1处于第一工作位(图中最右方)时，第一密封区段11对第二通孔51的位于第一腔室1a与第二工作油口L之间的内壁表面进行密封，从而将第一腔室1a与第二工作油口L隔离，保证第一腔室1a只与外控油口X连通；同时，第二密封区段12对第二通孔51的位于第二腔室1b与第一工作油口Y之间的内壁表面进行密封，而第一密封区段11和第二密封区段12之间的颈缩段对第二通孔51的位于第二腔室1b与第二工作油口L之间的内壁表面形成避让，从而使得第二腔室1b与第二工作油口L连通并与第一工作油口Y隔离；第三密封区段13对第二通孔51的位于第一工作油口Y与第三腔室1c之间的内壁表面进行密封，同时，第三密封区段13和第四密封区段14之间的颈缩段对第二通孔51的位于第三腔室1c与反馈油口C之间的内壁表面形成避让，且第四密封区段14对第二通孔51的位于反馈油口C与弹簧腔之间的内壁表面进行密封，使得第三腔室1c与第一工作油口Y及弹簧腔均隔离，而只与反馈油口C连通。
而如图3所示，当阀芯1处于第二工作位(图中最左方)时，第一密封区段11仍对第二通孔51的位于第一腔室1a与第二工作油口L之间的内壁表面进行密封，实现第一腔室1a与第二工作油口L的隔离，保证第一腔室1a只与外控油口X连通；但不同地，第一密封区段11对第二通孔51的位于第二腔室1b与第二工作油口L之间的内壁表面进行密封，而第一密封区段11和第二密封区段12之间的颈缩段对第二通孔51的位于第二腔室1b与第一工作油口Y之间的内壁表面形成避让，从而使得第二腔室1b改变为与第一工作油口Y连通并与第二工作油口L隔离；第三密封区段13和第四密封区段14虽然向左移动，但第三密封区段13和第四密封区段14之间的颈缩段仍然对第二通孔51的位于第三腔室1c与反馈油口C之间的内壁表面形成避让，同时，第三密封区段13仍对第二通孔51的位于第一工作油口Y与第三腔室1c之间 的内壁表面进行密封，且第四密封区段14仍对第二通孔51的位于反馈油口C与弹簧腔之间的内壁表面进行密封，从而使得第三腔室1c仍与第一工作油口Y及弹簧腔均隔离，而仍只与反馈油口C连通。
可见，在该实施例中，当阀芯1处于第一工作位时，第一腔室1a与外控油口X连通，第二腔室1b与第二工作油口L及第三工作油口Z连通并与第一工作油口Y隔离，第三腔室1c与反馈油口C连通；而当阀芯1处于第二工作位时，第一腔室1a与外控油口X连通，第二腔室1b与第一工作油口Y及第三工作油口Z连通并与第二工作油口L隔离，第三腔室1c与反馈油口C连通。
下面结合图2和图3对该实施例行走马达换挡阀100控制换挡的原理及边界条件进行说明。
首先，为了方便描述，将第一工作油口Y、第二工作油口L、第三工作油口Z、外控油口X及反馈油口C的压力分别定义为P Y、P L、P Z、P X及P C，并将第一腔室1a、第二腔室1b和第三腔室1c的有效压力作用面积分别定义为A 1、A 2和A 3，将弹簧4在第一工作位和第二工作位对阀芯1施加的作用力分别定义为F 1和F 2，且将马达400在第一工作位和第二工作位时的排量分别定义为V 1和V 2。由于第二工作油口L与油箱连通，因此，可以认为P L＝0。另外，由于如前所述，第一工作油口Y和反馈油口C的压力实际上均为马达400的实际工作压力，因此，P Y＝P C。
基于上述，由于如图2所示和如前所述，当阀芯1处于第一工作位，第一腔室1a与外控油口X连通，第二腔室1b与第二工作油口L及第三工作油口Z连通，第三腔室1c与反馈油口C连通，且弹簧4的弹性力为F 1，因此，在忽略液动力和摩擦力对阀芯1在第二通孔51中滑动的影响，可以得到阀芯1此时的受力平衡状态方程为：
P X×A 1+P L×A 2＝P C×A 3+F 1      (1)。
由于P L＝0，因此，可以推导出在外控油口X控制压力P X的作用下，能够将阀芯1由第一工作位推动至第二工作位，即，能够将行走马达由低速模式切换至高速模式的反馈油口C的压力P C(即马达400的实际工作压力)应满足：
P C＜(P X×A 1-F 1)/A3      (2)。
进而可知，在外控油口X控制压力P X的作用下，将行走马达由低速模式切换至高速模式的边界条件(简称为边界条件1)为：
P C1＝(P X×A 1-F 1)/A3      (3)。
该P C1被称为第一预设值。由此可知，当反馈油口C的油压小于第一预设值P C1时， 阀芯1能够由第一工作位移动至第二工作位。
而由于如图3所示和如前所述，当阀芯1处于第二工作位时，第一腔室1a与外控油口X连通，第二腔室1b与第一工作油口Y及第三工作油口Z连通，第三腔室1c与反馈油口C连通，弹簧4的弹性力为F 2，因此，在忽略液动力和摩擦力对阀芯1在第二通孔51中滑动的影响，可以得到阀芯1此时的受力平衡状态方程为：
P X×A 1+P Y×A 2＝P C×A 3+F 2      (4)。
由于P Y＝P C，因此，可以推导出阀芯1能够由第二工作位移动至第一工作位，即，行走马达能够由高速模式切换至低速模式的反馈油口C的压力P C(即马达400的实际工作压力)应满足：
P C＞(P X×A 1-F 2)/(A 3-A 2)      (5)。
进而可知，将行走马达由高速模式切换至低速模式的边界条件(简称为边界条件2)为：
P C2＝(P X×A 1-F 2)/(A 3-A 2)      (6)。
该P C2被称为第二预设值。由此可知，当反馈油口C的油压大于第二预设值P C2时，阀芯1能够由第二工作位移动至第一工作位。
为了防止由于基于同一预设值进行换挡所造成的反复切换的问题，该实施例将第一预设值P C1与第二预设值P C2设置为不相等的，从而基于公式(3)和公式(6)，可以得到三个腔室的面积A 1、A 2和A 3之间的相应关系。
而且，进一步地，该实施例还在考虑行走马达高低速模式下的排量情况的基础上，通过对三个腔室的面积A 1、A 2和A 3进行设计，来控制换挡后马达400的实际工作压力值，使得由低速切换至高速后马达400的实际工作压力值不满足边界条件2，从而能够按照预期稳定保持于高速模式，并使得由高速切换至低速后马达400的实际工作压力值不满足边界条件1，从而能够按照预期稳定地保持于低速模式，进而更有效地防止高低速反复切换现象地发生。
为了方便描述，将阀芯1由第一工作位移动至第二工作位(即行走马达由低速切换至高速)后反馈油口C的油压(即马达400的实际工作压力)计为第一工作值P C3，并将阀芯1由第二工作位移动至第一工作位(即行走马达由低速切换至高速)后反馈油口C的油压(即马达400的实际工作压力)计为第二工作值P C4。
基于此，为了使由低速切换至高速后马达400的实际工作压力值不满足边界条件2，便于控制行走马达稳定于高速模式下，在该实施例中，第一工作值P C3满足的边界 条件(简称为边界条件3)为：
P C3＜K 1P C2，K 1＜1，      (7)。
其中，由于马达400的最大输入功率为一恒定值，马达400的输出扭矩T与马达400的排量V和输入口压力(即实际工作压力)P满足：T＝K×V×P，其中K为比例系数，因此，马达400的输出扭矩T与马达400的排量V和输入口压力(即实际工作压力)P之间成正比，从而，若马达由低速切换至高速时的实际工作压力为P C1，则切换后的实际工作压力P C3与P C1之间满足：P C3×V 2＝P C1×V 1，从而可以推导出第一工作值P C3为：
Figure PCTCN2018079068-appb-000003
进而，由公式(7)、公式(8)和公式(3)，可以确定三个腔室的面积A 1、A 2和A 3之间的相应关系。
另外，类似地，为了使由高速切换至低速后马达400的实际工作压力值不满足边界条件1，便于控制行走马达稳定于低速模式下，在该实施例中，第二工作值P C4满足的边界条件(简称为边界条件3)为：
P C4＞K 2P C1，K 2＞1，      (9)。
其中，若马达由高速切换至低速时的实际工作压力为P C2，则切换后的实际工作压力P C4与P C2之间满足：P C4×V 1＝P C2×V 2，从而可以推导出第一工作值P C4为：
Figure PCTCN2018079068-appb-000004
进而，由公式(10)、公式(9)和公式(6)，可以确定三个腔室的面积A 1、A 2和A 3之间的相应关系。
由上述可知，综合边界条件1、边界条件2、边界条件3和边界条件4，可以确定第一腔室1a、第二腔室1b和第三腔室1c的有效压力作用面积A 1、A 2和A 3之间的关系。换句话说，可以通过对有效压力作用面积A 1、A 2和A 3进行设计，来使行走马达换挡阀100能够在控制行走马达换挡后较稳定地保持于所期望的速度模式下，而不至于反复切换、引起整机颤动。
所以，依据边界条件1、边界条件2、边界条件3及边界条件4，对图2-4所示的行走马达换挡阀100的第一腔室1a的有效压力作用面积A 1、第二腔室1b的有效压力作用面积A 2以及第三腔室1c的有效压力作用面积A 3进行设计与校核，可以有效防止行走马达高低速反复切换。设计完成后，行走马达换挡阀100的工作流程可以如下：
当行走马达的实际工作压力大于P C1时，外控油无法推动阀芯1左移，行走马达仅能在低速模式下运行；当行走马达的实际工作压力小于P C1时，外控油推动阀芯1左移，待左移至最左方、阀芯1切换至第二工作位(行走马达切换至高速模式)时，由边界条件3的限制，行走马达压力将低于K 1P C2，由于不满足边界条件2，因此，行走马达能够稳定在高速模式下工作；而当行走马达的实际工作压力大于P C2时，在弹簧力与各密闭腔的共同作用下，阀芯1右移，由边界条件4的限制，当切换至低速模式后，行走马达压力将高于K 2P C1，由于不满足边界条件1，因此，行走马达将稳定在低速模式下运行。
可见，该实施例中通过使行走马达换挡阀100具有第一腔室1a、第二腔室1b和第三腔室1c，并分别对第一腔室1a、第二腔室1b和第三腔室1c的有效压力作用面积A 1、A 2和A 3进行设计，可以控制行走马达在换挡后能够稳定地保持于所相应的工作模式下，而不会频繁地反复切换，从而能够有效地解决整机颤动问题，有利于延长行走马达换挡阀100、行走马达乃至工程机械产品的寿命，提高工程机械行驶的安全性。而且，由于无需附加额外的控制元件及检测元件等，因此，整体结构较为简单，控制较为方便，控制精度及工作可靠性相对较高，同时，成本也较低。
虽然，在未图示的其他实施例中，第二腔室1b和第三腔室1c也可以不设置于阀芯1上，例如可以设置于阀芯1与壳体5或专门的阀体之间，但该实施例将第二腔室1b和第三腔室1c设置于阀芯1上，其好处在于，可以使得行走马达换挡阀100的结构较为简单紧凑，油路设计较为方便，且使得只需主要对阀芯1的结构进行设计，即可降低高低速反复切换的风险，更加简单方便。
另外，虽然图4所示的阀芯1，其四个密封区段的直径相同，但应当理解，这并不构成对本公开的限制，例如，将阀芯1的不同密封区段设置为具有不同的直径，或者在壳体5等上开设一些辅助孔道，也是可行的。
基于本公开的行走马达换挡阀100，本公开还提供了一种行走马达和一种工程机械。其中，行走马达包括马达400和与马达400的斜盘驱动连接的斜盘控制机构500，并且，其还包括本公开的行走马达换挡阀100，行走马达换挡阀100设置于马达400的壳体5内部。而工程机械则包括本公开的行走马达。本公开的工程机械例如可以为挖掘机等履带机械。
以上仅为本公开的示例性实施例，并不用以限制本公开，凡在本公开的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本公开的保护范围之内。

Claims (15)

  1. 一种行走马达换挡阀(100)，其中，包括阀芯(1)、第一工作油口(Y)、第二工作油口(L)、第三工作油口(Z)、外控油口(X)和反馈油口(C)，所述阀芯(1)具有第一工作位和第二工作位，在所述第一工作位时，所述第一工作油口(Y)截止且所述第二工作油口(L)与所述第三工作油口(Z)连通，在所述第二工作位时，所述第一工作油口(Y)与所述第三工作油口(Z)连通且所述第二工作油口(L)截止；所述第一工作油口(Y)用于与油源连通，所述第二工作油口(L)用于与油箱连通，所述第三工作油口(Z)用于与行走马达的斜盘控制机构(500)连通；所述外控油口(X)用于引导控制油作用于所述阀芯(1)的轴向第一端并使所述阀芯(1)产生由所述第一工作位向所述第二工作位移动的趋势，所述反馈油口(C)用于将所述行走马达的马达(400)的实际工作压力反馈至所述阀芯(1)的轴向第二端并使所述阀芯(1)产生由所述第二工作位向所述第一工作位移动的趋势，并且，所述行走马达换挡阀(100)被设置为使得：
    所述反馈油口(C)的油压小于第一预设值P C1时，所述阀芯(1)能够由所述第一工作位移动至所述第二工作位，所述反馈油口(C)的油压大于第二预设值P C2时，所述阀芯(1)能够由所述第二工作位移动至所述第一工作位，其中，所述第一预设值P C1与所述第二预设值P C2不相等；
    并且，所述阀芯(1)由所述第一工作位移动至所述第二工作位后，所述反馈油口(C)的油压为第一工作值P C3，所述阀芯(1)由所述第二工作位切换至所述第一工作位后，所述反馈油口(C)的油压为第二工作值P C4，其中，所述第一工作值P C3与所述第二预设值P C2之间满足P C3<K 1P C2，K 1≤1，且所述第二工作值P C4与所述第一预设值P C1之间满足P C4>K 2P C1，K 2≥1。
  2. 根据权利要求1所述的行走马达换挡阀(100)，其中，所述行走马达换挡阀(100)还包括第一腔室(1a)、第二腔室(1b)和第三腔室(1c)，所述第一腔室(1a)与所述外控油口(X)连通，所述第三腔室(1c)与所述反馈油口(C)连通，所述第二腔室(1b)与所述第三工作油口(Z)连通并在所述阀芯(1)由所述第一工作位向所述第二工作位移动的过程中切换地与所述第二工作油口(L)和所述第一工作油口(Y)连通，且所述第二腔室(1b)的有效压力作用面积小于所述第三腔室(1c)的有效压力作用面积。
  3. 根据权利要求2所述的行走马达换挡阀(100)，其中，所述行走马达换挡阀(100)还包括弹簧(4)，所述弹簧(4)设置于所述阀芯(1)的轴向第二端并对所述阀芯(1)施加使所述阀芯(1)产生由所述第二工作位向所述第一工作位移动趋势的作用力，所述第一预设值P C1为P C1＝(P X×A 1-F 1)/A 3，所述第二预设值P C2为P C2＝(P X×A 1-F 2)/(A 3-A 2)，所述第一工作值
    Figure PCTCN2018079068-appb-100001
    所述第二工作值为
    Figure PCTCN2018079068-appb-100002
    其中，P X为所述外控油口(X)的油压，A 1、A 2和A 3分别为所述第一腔室(1a)、所述第二腔室(1b)和所述第三腔室(1c)的有效压力作用面积，F 1和F 2分别为所述弹簧(4)在所述第一工作位和所述第二工作位对所述阀芯(1)施加的作用力，V 1和V 2分别为所述马达(400)在所述第一工作位和所述第二工作位时的排量。
  4. 根据权利要求2所述的行走马达换挡阀(100)，其中，所述第二腔室(1b)和所述第三腔室(1c)设置于所述阀芯(1)上并分别位于所述阀芯(1)的轴向第一端和轴向第二端。
  5. 根据权利要求4所述的行走马达换挡阀(100)，其中，所述阀芯(1)的轴向第一端和轴向第二端分别设有第一柱塞腔(1f)和第二柱塞腔(1g)，所述第一柱塞腔(1f)中设有第一柱塞(21)，所述第二柱塞腔(1g)中设有第二柱塞(22)，所述第二腔室(1b)位于所述第一柱塞(21)与所述第一柱塞腔(1f)的内壁之间，所述第三腔室(1c)位于第二柱塞(22)与所述第二柱塞腔(1g)的内壁之间。
  6. 根据权利要求4所述的行走马达换挡阀(100)，其中，所述阀芯(1)上还设有第一通道(1d)，所述第二腔室(1b)通过所述第一通道(1d)与所述第一工作油口(Y)和所述第二工作油口(L)中的一个连通；和/或，所述阀芯(1)上还设有第二通道(1e)，所述第三腔室(1c)通过所述第二通道(1e)与所述反馈油口(C)连通。
  7. 根据权利要求1所述的行走马达换挡阀(100)，其中，所述行走马达换挡阀(100)还包括第一封堵件(31)，所述第一封堵件(31)设置于所述阀芯(1)的轴向第二端，所述行走马达换挡阀(100)的弹簧(4)抵设于所述第一封堵件(31)与所述阀芯(1)的轴向第二端之间并对所述阀芯(1)施加使所述阀芯(1)产生由所述第二工作位向所述第一工作位移动趋势的作用力。
  8. 根据权利要求7所述的行走马达换挡阀(100)，其中，所述第一封堵件(31) 的靠近所述阀芯(1)的表面上设有弹簧容纳腔(31c)，所述弹簧(4)设置于所述弹簧容纳腔(31c)中。
  9. 根据权利要求8所述的行走马达换挡阀(100)，其中，所述第一封堵件(31)上还设有第一通孔(31a)，所述第一通孔(31a)与所述弹簧容纳腔(31c)连通。
  10. 根据权利要求7所述的行走马达换挡阀(100)，其中，所述第一封堵件(31)的远离所述阀芯(1)的表面上设有紧固槽(31b)。
  11. 根据权利要求1所述的行走马达换挡阀(100)，其中，所述阀芯(1)的轴向第一端具有颈缩部。
  12. 根据权利要求11所述的行走马达换挡阀(100)，其中，所述颈缩部的周向表面上设有凹槽(15)。
  13. 一种行走马达，包括马达(400)和与所述马达(400)的斜盘驱动连接的斜盘控制机构(500)，其中，还包括如权利要求1所述的行走马达换挡阀(100)，所述行走马达换挡阀(100)设置于所述马达(400)的壳体(5)内部。
  14. 根据权利要求13所述的行走马达，其中，所述壳体(5)上设有第二通孔(51)，所述行走马达换挡阀(100)的阀芯(1)容置于所述第二通孔(51)中，且所述行走马达换挡阀(100)的第一工作油口(Y)、第二工作油口(L)、第三工作油口(Z)、外控油口(X)和反馈油口(C)均设置于所述壳体(5)的内壁上。
  15. 一种工程机械，其中，包括如权利要求13所述的行走马达。
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