Operating mode switching control system and excavator

Abstract

This invention relates to excavators, and specifically to an operating mode switching control system and an excavator. The system includes a hydraulically controlled mode switching valve, a mode control valve, a control unit, and a mode setting device. The mode control valve has a control port connected to the hydraulic control end of the mode switching valve, an inlet port connected to a pilot oil source, and a return port connected to a return oil circuit. In the left position, the inlet port is connected to the control port; in the middle position, the control port is closed; and in the right position, the control port is connected to the return port. The control unit is electrically connected to the mode control valve and is used to control the mode control valve to intermittently switch between the left and middle positions in a second operating mode. In this invention, the mode switching valve can operate in the second operating mode by intermittently energizing the mode control valve. This intermittent energization reduces heat generation and extends the valve's lifespan.

Description

Technical Field

[0001] This invention relates to an excavator, and more specifically, to an operating mode switching control system and an excavator. Background Technology

[0002] Construction machinery such as excavators typically include actions or similar movements such as boom raising and lowering, stick retraction and extension, bucket retraction and extension, and slewing. For excavators, the boom, stick, bucket, and slewing movements are all controlled by two levers. Generally, the left lever controls stick outward swing, stick retraction, upper left rotation, and upper right rotation in four directions, respectively; the right lever controls boom lowering, boom raising, bucket retraction, and bucket outward swing in four directions, respectively. Due to differences between manufacturers, the operating modes of some machines may vary slightly, leading to different familiarity and proficiency among excavator operators. Selecting the appropriate operating mode for different excavator working conditions can effectively improve work efficiency; therefore, convenient and quick switching between operating modes is particularly important.

[0003] The current mainstream solution uses a mechanical switching valve, which controls the flow of pilot control oil to switch actions and achieve different operating modes. Compared to switching by reconnecting the hydraulic lines on the handle, this method not only improves the efficiency of switching operating modes but also effectively avoids hydraulic oil leakage and environmental pollution during pipeline disassembly, and reduces the likelihood of machine malfunction due to foreign object contamination of the hydraulic system. However, since the switching valve is usually installed outside the cab, the operator needs to get out of the machine and use tools to switch operating modes each time. Furthermore, the location of the switching valve varies depending on the layout of different machines, reducing the efficiency of operating mode switching. With the increasing automation requirements of excavators, mechanical switching valves no longer meet the requirements.

[0004] The latest control method uses an electromagnetic switching valve to switch operating modes. Operators can directly switch modes from the cab, and the mode status is displayed on the instrument panel. The control principle is that when the operator toggles the switching button, the electromagnet on one side of the electromagnetic switching valve is energized, causing the valve core to reverse and completing the oil circuit switch, thus achieving rapid mode switching. The electromagnetic switching valve is a two-position valve. One working position is held by a spring when the electromagnet is de-energized, while the other working position requires the electromagnet to be energized to overcome the spring force. To maintain the switched mode, the electromagnetic coil needs to be continuously energized, which can easily cause the coil to overheat, increase current loss, and affect the lifespan of the electromagnetic valve. Furthermore, each time the entire machine is shut down, the operating mode defaults to the initial state due to the de-energization of the electromagnetic valve. If the electrical function fails after restarting the machine, and the operator is accustomed to the switched mode, operating the entire machine may pose a safety risk. Moreover, if the electrical control of the electromagnetic valve fails, the electromagnetic switching valve cannot switch modes, thus affecting the operator's work efficiency. Summary of the Invention

[0005] The technical problem to be solved by the present invention is the drawback of electromagnetic switching valve switching in the existing operation mode switching control system, and the present invention provides an operation mode switching control system and an excavator.

[0006] The technical solution of the present invention to achieve its purpose is: an operation mode switching control system, including a mode switching valve, a mode control valve, a control unit, and a mode setting device disposed on the pilot control oil circuit for switching between a first operation mode and a second operation mode;

[0007] The mode switching valve is a hydraulically controlled valve;

[0008] The mode control valve has a control terminal electrically connected to the control unit, and has a control port connected to the hydraulic control terminal of the mode switching valve, an inlet port connected to the pilot oil source, and a return port connected to the return oil circuit. When in the left position, the inlet port is connected to the control port, when in the middle position, the control port is cut off, and when in the right position, the control port is connected to the return port.

[0009] The mode setting device is electrically connected to the control unit and is used to input the first operation mode working command and the second operation mode working command.

[0010] The control unit is used to control the mode control valve to intermittently switch between the left and middle positions in the second operating mode.

[0011] In the operation mode switching control system of the present invention, the control unit is configured to control the mode control valve to work in the middle position in the first operation mode, and when the mode setting device outputs the working command to switch from the second operation mode to the first operation mode, it controls the mode control valve to switch to the right position and then switch to the middle position.

[0012] In the operation mode switching control system of the present invention, the hydraulic control end of the mode switching valve is connected to an accumulator.

[0013] In the operation mode switching control system of the present invention, the mode switching valve has a manual switching lever for manual switching and reversing.

[0014] In the operation mode switching control system of the present invention, the mode setting device is configured as an in-vehicle instrument capable of displaying the current operation mode.

[0015] In the operation mode switching control system of the present invention, the control unit includes a timing module, and the control unit is configured to periodically control the mode control valve to switch between the left position and the middle position in the second operation mode.

[0016] In the operating mode switching control system of the present invention, the system further includes a pressure detection device for detecting the pressure at the hydraulic control end of the mode switching valve and electrically connected to the control unit. The control unit is configured to control the mode control valve to operate in the left position in the second operating mode when the pressure at the hydraulic control end of the mode switching valve is less than a preset value; or the system further includes a valve stem position sensor for detecting the valve stem position of the mode switching valve. The control unit is configured to control the mode control valve to operate in the left position in the second operating mode when the valve stem of the mode switching valve is reset to a predetermined position.

[0017] In the operation mode switching control system of this invention, the mode control valve is a three-position three-way solenoid valve. Alternatively, the mode control valve includes a three-position four-way solenoid valve and a hydraulically controlled check valve; the first port of the three-position four-way solenoid valve is an inlet, the second port is a return port, the third port is connected to the forward-flowing inlet end of the hydraulically controlled check valve, and the fourth port is connected to the hydraulically controlled end of the hydraulically controlled check valve; the outlet end of the hydraulically controlled check valve is a control port; when the three-position four-way solenoid valve is in the left position, the first port and the third port are connected; when it is in the middle position, the first port is cut off; and when it is in the right position, the first port and the fourth port are connected, and the second port and the third port are connected.

[0018] Compared with the prior art, in this invention, the mode switching valve adopts a hydraulic control valve and is controlled by a mode control valve. In the second working mode, the mode control valve intermittently switches between the left and middle positions, thereby keeping the pressure at the hydraulic control end of the mode switching valve within a certain range so that the mode switching valve works in the second operating mode. The intermittent energization of the mode control valve reduces its heat generation and extends its service life. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the operation mode switching control system of the present invention.

[0020] Figure 2This is another control principle diagram of the mode switching valve in the operation mode switching control system of the present invention.

[0021] Component names and serial numbers in the diagram:

[0022] First pilot valve 10, second pilot valve 11, pilot control oil circuit 12, mode switching valve 21, mode control valve 22, manual switching lever 23, pressure detection device 24, three-position four-way solenoid valve 221, hydraulic control check valve 222, first control main valve 30, second control main valve 31, control unit 40, mode setting device 50. Detailed Implementation

[0023] The specific implementation plan is described below with reference to the attached diagram.

[0024] Example 1.

[0025] The operation mode switching control system includes a mode switching valve 21, a mode control valve 22, a control unit 40, and a mode setting device 50, which are installed on the pilot control oil circuit 12 for switching between a first operation mode and a second operation mode.

[0026] The mode control valve 22 is used to control the mode switching valve 21 to operate in the left or right position. The control unit 40 is used to control the mode control valve 22 to operate in the left, middle, or right position.

[0027] like Figure 1 As shown, the mode switching valve 21 is a hydraulic control valve. The mode control valve 22 has a control port (D port) connected to the hydraulic control end of the mode switching valve 21, an inlet port (P port) connected to the pilot oil source, and a return port (T port) connected to the return oil circuit. When in the left position, the inlet port (P port) and the control port (D port) are connected; when in the middle position, the control port (D port) is cut off; and when in the right position, the control port (D port) and the return port (T port) are connected.

[0028] The mode setting device 50 is electrically connected to the control unit 40 and is used to input the first operation mode working command and the second operation mode working command.

[0029] When the control unit 40 receives a first operating mode command or a second operating mode command, it outputs a control current to the mode control valve 22 to make the operating mode switching control system operate in the first operating mode or the second operating mode.

[0030] The control unit 40 is electrically connected to the electronic control terminal of the mode control valve 22 and is used to control the mode control valve 22 to intermittently switch between the left position and the middle position in the second working mode.

[0031] like Figure 1As shown, the mode switching valve 21 is installed on the pilot control oil circuit 12, which has two sets of pilot valves: a first pilot valve 10 and a second pilot valve 11. The two sets of pilot valves are used to control two main control valves: a first main control valve 30 and a second main control valve 31.

[0032] The mode switching valve 21 is a two-position valve. When the force of the hydraulic oil at its pilot end acting on the valve stem is less than the spring force of the spring cavity, it is in the left position. In this position, port A1 is connected to port P1, port B1 to port T1, port A2 to port P2, and port B2 to port T2. At this time, the first pilot valve 10 controls the first control main valve 30, and the second pilot valve 11 controls the second control main valve 31. This is the first operating mode. When the pilot end of the mode switching valve 21 is filled with pilot pressure oil at a certain pressure, and the force of the hydraulic oil at the pilot end acting on the valve stem is greater than the spring force of the spring cavity, the mode switching valve 21 is in the right position. In this position, port A1 is connected to port T1, port B1 to port P1, port A2 to port T2, and port B2 to port P2. At this time, the first pilot valve 10 controls the second control main valve 31, and the second pilot valve 11 controls the first control main valve 30. This is the second operating mode. The first operating mode and the second operating mode can be switched by controlling the working position of the mode switching valve 21.

[0033] The mode control valve 22 is a three-position, three-way solenoid valve. Its control port (D port) is connected to the hydraulic control end of the mode switching valve 21, its inlet port (P port) is connected to the pilot oil source, and its return port (T port) is connected to the return oil circuit. The pilot oil source provides pilot pressure oil for the pilot control of the hydraulic system. It can be provided by a pilot pump or obtained by reducing the pressure from the main working oil circuit connected to the main pump port of the hydraulic system through the pilot supply valve. The return oil circuit is connected to the hydraulic oil tank.

[0034] When the mode control valve 22 is in the left position, the inlet port (P port) and the control port (D port) are connected. The pilot pressure oil provided by the pilot oil source enters the hydraulic control end of the mode switching valve 21 through the inlet port (P port) and the control port (D port) of the mode control valve 22, pushing the valve stem of the mode switching valve 21 to move to the left, so that the mode switching valve 21 works in the right position.

[0035] When mode control valve 22 is in the neutral position, the control port (D port) is closed. Because the control port (D port) is closed, the pilot oil at the hydraulic control end of mode switching valve 21 is blocked and cannot flow back to the hydraulic oil tank. Therefore, when mode control valve 22 switches from the left position to the neutral position, the valve stem of mode switching valve 21 cannot return from the right position to the left position because the oil at the hydraulic control end cannot flow back to the hydraulic oil tank. Thus, mode switching valve 21 still operates in the right position.

[0036] When the mode control valve 22 is in the right position, the control port (D port) and the return port (T port) are connected. The hydraulic control end of the mode switching valve 21 is connected to the return oil circuit through the control port (D port) and the return port (T port) of the mode control valve 22. The valve stem of the mode switching valve 21 is reset under the action of the spring force in its spring chamber. When the mode switching valve 21 is in the left position, it switches from the second operating mode to the first operating mode.

[0037] The mode setting device 50 is electrically connected to the control unit 40. The mode setting device 50 is used to input a first operating mode command and a second operating mode command, so that the mode switching valve 21 operates in either the first or second operating mode. The control unit 40 can be a controller, such as the overall controller of an excavator. The mode setting device 50 can be an on-board instrument for the machine, allowing for operation mode setting and displaying the current operating mode.

[0038] In this embodiment, when the operator sets the machine's operating mode to the second operating mode (previously the first operating mode) via the mode setting device 50, the control unit 40 controls the mode control valve 22 to operate in the left position, and the mode switching valve 21 switches to the right position, operating in the second operating mode. Subsequently, the control unit 40 controls the mode control valve 22 to operate in the middle position, preventing oil from flowing out of the hydraulic control end of the mode switching valve 21, and the mode switching valve 21 continues to operate in the right position, maintaining the second operating mode.

[0039] When mode control valve 22 is in the neutral position, the return oil passage of the hydraulic control end of mode switching valve 21 is blocked by mode control valve 22. Under the pressure of the spring pushing the valve stem in the spring chamber, the hydraulic pressure at the hydraulic control end of mode switching valve 21 is higher than the atmospheric pressure (pressure of the hydraulic oil tank). Since both mode control valve 22 and mode switching valve 21 are spool valves, leakage is inevitable. The oil at the hydraulic control end of mode switching valve 21 also leaks under the pressure of the valve stem. Therefore, when mode control valve 22 is in the neutral position, mode switching valve 21 slowly resets to the left position. To prevent mode switching valve 21 from automatically resetting to the first operating mode in the second operating mode, in the second operating mode, control unit 40 controls mode control valve 22 to intermittently switch between the left and neutral positions, that is, intermittently fills the hydraulic control end of mode switching valve 21, so that mode switching valve 21 always works in the right position. The interval between switching mode control valve 22 between the left and middle positions depends on the rate of oil leakage from the hydraulic control end of mode switching valve 21. If the oil leakage is negligible, the interval between switching mode control valve 22 from the middle to the left position in the second operating mode will be longer. If the oil leakage is more significant, the interval between switching mode control valve 22 from the middle to the left position in the second operating mode will be shorter, and may even require frequent periodic switching.

[0040] When the operator sets the machine's operating mode to the first operating mode (previously the second operating mode) via the mode setting device 50, the control unit 40 controls the mode control valve 22 to operate in the right position. The hydraulic control end of the mode switching valve 21 is connected to the return oil circuit via the control oil port (D port) and return oil port (T port) of the mode control valve 22. Under the action of the spring force in its spring chamber, the mode switching valve 21 resets to the left position, and the mode switching valve 21 also switches from the second operating mode to the first operating mode. After the mode switching valve 21 switches to the left position, the mode control valve 22 is de-energized and automatically resets to the neutral position. When the mode control valve 22 resets to the neutral position, the mode switching valve 21 remains in the left position.

[0041] Optionally, an accumulator (not shown in the figure) is connected to the hydraulic control terminal of the mode switching valve 21. When the mode switching valve 21 switches from the right position to the left position, the volume change at its hydraulic control terminal is small. If the speed at which oil leaks out from the hydraulic control terminal of the mode switching valve 21 is fast, the time for the mode switching valve 21 to reset from the right position to the left position is short. With the accumulator connected to the hydraulic control terminal of the mode switching valve 21, when oil leaks out from the hydraulic control terminal of the mode switching valve 21, the accumulator can release supplementary oil to the hydraulic control terminal of the mode switching valve 21, thereby extending the time for the mode switching valve 21 to switch from the right position to the left position.

[0042] Optionally, the operation mode switching control system may also be equipped with a pressure detection device 24 electrically connected to the control unit 40. The pressure detection device 24 is used to detect the pressure at the hydraulic control end of the mode switching valve 21. As the oil leaks from the hydraulic control end of the mode switching valve 21, the spring in the spring chamber of the mode switching valve 21 is released due to the movement of the valve stem, and the pressure at the hydraulic control end of the mode switching valve 21 also decreases accordingly. By detecting the pressure at the hydraulic control end of the mode switching valve 21 through the pressure detection device 24, the degree of reset of the mode switching valve 21 in the second operation mode can be determined. In the second operation mode, when the pressure at the hydraulic control end of the mode switching valve 21 drops to a certain value, the control unit 40 controls the mode control valve 22 to operate in the left position for a certain period of time, and then controls the mode control valve 22 to return to the middle position. When the mode control valve 22 is operating in the left position, oil is replenished to the hydraulic control end of the mode switching valve 21 so that the mode switching valve 21 always operates in the right position. The pressure detection device 24 can be a pressure sensor, a pressure switch, or a pressure relay. When the pressure at the hydraulic control end of the mode switching valve 21 is lower than a predetermined value, the control unit 40 can obtain a trigger electrical signal from the pressure detection device 24 that can be used for judgment.

[0043] To detect the degree to which the mode switching valve 21 resets to the left position when it is in the right position, a valve stem position sensor (not shown in the figure) can also be installed. The valve stem position sensor is connected to the valve stem of the mode switching valve. When the mode switching valve 21 resets from the right position to the left position, the valve stem position sensor triggers and sends a corresponding electrical signal to the control unit 40 when it resets to the predetermined position. In the second operating mode, when the control unit 40 receives the trigger signal from the valve stem position sensor, the control unit 40 controls the mode control valve 22 to operate in the left position for a certain period of time before controlling the mode control valve 22 to return to the neutral position. When the mode control valve 22 is in the left position, oil is added to the hydraulic control end of the mode switching valve 21 to keep the mode switching valve always operating in the right position.

[0044] In the second operating mode, in order to keep the mode switching valve 21 always working in the right position, it can also be achieved by periodically filling the hydraulic control end of the mode switching valve with liquid. That is, the control unit 40 controls the mode control valve 22 to periodically switch from the middle position to the left position. For this purpose, a timing module and timing cycle can be set in the control unit 40. The control unit 40 is configured to periodically control the mode control valve 22 to switch between the left position and the middle position in the second operating mode with one timing cycle as the cycle.

[0045] Optionally, in the operation mode switching control system, the mode switching valve 21 has a manual switching lever 23 for manual switching. The manual switching lever 23 is connected to the valve stem of the mode switching valve 21. By pulling the manual switching lever 23, the valve stem of the mode switching valve 21 can be moved, thereby enabling the mode switching valve 21 to switch between the first operation mode and the second operation mode. The manual switching lever 23 is provided so that when the mode control valve 22, control unit 40, mode setting device 50, etc., malfunction and mode switching cannot be performed, the operation mode of the mode switching valve 21 can be switched using the manual switching lever 23.

[0046] This embodiment also provides an excavator having the aforementioned operation mode switching control system.

[0047] Example 2.

[0048] Compared with Embodiment 1, the difference in the operation mode switching control system of this embodiment lies in the mode control valve 22.

[0049] like Figure 2 As shown, in this embodiment, the mode control valve 22 includes a three-position four-way solenoid valve 221 and a hydraulically controlled check valve 222.

[0050] The first port (e port) of the three-position four-way solenoid valve 221 is the inlet port (P port), the second port (f port) is the return port (T port), the third port (g port) is connected to the forward-flow inlet end of the hydraulic control check valve 222, and the fourth port (h port) is connected to the hydraulic control end of the hydraulic control check valve 222; the outlet end of the hydraulic control check valve 222 is the control port (D port).

[0051] The three working positions of the three-position four-way solenoid valve 221 (left, middle, and right) correspond one-to-one with the three working positions of the mode control valve 22 (left, middle, and right). When the three-position four-way solenoid valve 221 is in the left position, the first port (e) and the third port (g) are connected. When the three-position four-way solenoid valve 221 is in the middle position, the first port (e) is closed, and at this time, the third port (g) and the fourth port (h) can both be connected to the second port (f), thus preventing the hydraulic control check valve 222 from accidentally opening due to pressure buildup caused by valve leakage at the hydraulic control end. When in the right position, the first port (e) and the fourth port (h) are connected, and the second port (f) and the third port (g) are connected.

[0052] When the mode control valve 22 is in the left position, the pilot oil from the inlet (P port) flows forward through the left position oil path of the three-position four-way solenoid valve 221, through the pilot check valve 222, and into the pilot end of the mode switching valve 21, thus placing the mode switching valve 21 in the right position. When the mode control valve 22 is in the neutral position, because the three-position four-way solenoid valve 221 is in the neutral position, the pilot check valve 222 is in the reverse cut-off state. The oil at the pilot end of the mode switching valve 21 cannot leak outward through the pilot check valve 222 and the neutral position oil path of the three-position four-way solenoid valve 221, thereby reducing the rate of leakage. When the mode control valve 22 is in the right position, since the three-position four-way solenoid valve 221 is also in the right position, the pilot pressure oil from the inlet (P port) acts on the hydraulic control end of the hydraulic check valve 222 through the right-position oil passage (e port and h port are connected) of the three-position four-way solenoid valve 221. The hydraulic check valve 222 is in the reverse conduction state. The oil at the hydraulic control end of the mode switching valve 21 flows to the return oil passage through the control oil port (D port), the right-position oil passage (g port and f port are connected) of the three-position four-way solenoid valve 221, and the return oil port (T port), thereby switching the mode switching valve 21 from the right position to the left position. The operation mode switching control system also switches from the second operation mode to the first operation mode. The valve core and valve body of the hydraulic check valve 222 can be sealed by a conical line contact, which has good sealing performance.

[0053] In this embodiment, the mode switching valve 21 is hydraulically controlled, and its switching is controlled by an electrically controlled mode control valve 22. In the second operating mode, the mode switching valve 21 is kept in the right position by intermittently controlling the mode control valve 22. The intermittent energization of the mode control valve 22 reduces its heat generation, lowers its failure rate, and extends its service life.

Claims

1. An operating mode switching control system, comprising a mode switching valve disposed in a pilot control oil circuit for switching between a first operating mode and a second operating mode, characterized in that, It also includes a mode control valve, a control unit, and a mode setting device; The mode switching valve is a hydraulically controlled valve; The mode control valve has a control terminal electrically connected to the control unit, and has a control port connected to the hydraulic control terminal of the mode switching valve, an inlet port connected to the pilot oil source, and a return port connected to the return oil circuit. When in the left position, the inlet port is connected to the control port, when in the middle position, the control port is cut off, and when in the right position, the control port is connected to the return port. The mode setting device is electrically connected to the control unit and is used to input the first operation mode working command and the second operation mode working command. The control unit is used to control the mode control valve to intermittently switch between the left and middle positions in the second working mode. The mode control valve intermittently fills the hydraulic control end of the mode switching valve so that the mode switching valve always works in the right position.

2. The operation mode switching control system according to claim 1, characterized in that, The control unit is configured to control the mode control valve to operate in the middle position in the first operating mode, and when the mode setting device outputs an operating command to switch from the second operating mode to the first operating mode, it controls the mode control valve to switch to the right position and then switch back to the middle position.

3. The operation mode switching control system according to claim 1, characterized in that, The mode switching valve is connected to an accumulator at its hydraulic control end.

4. The operation mode switching control system according to claim 1, characterized in that, The mode switching valve has a manual switching lever for manually switching the direction.

5. The operation mode switching control system according to claim 1, characterized in that, The mode setting device is configured as an in-vehicle instrument panel capable of displaying the current operating mode.

6. The operation mode switching control system according to claim 1, characterized in that, The control unit includes a timing module, and the control unit is configured to periodically control the mode control solenoid valve to switch between the left and middle positions in the second operating mode.

7. The operation mode switching control system according to claim 1, characterized in that: The system also includes a pressure detection device for detecting the pressure at the hydraulic end of the mode switching valve and electrically connected to the control unit. The control unit is configured to control the mode control valve to operate in the left position in the second operating mode when the pressure at the hydraulic end of the mode switching valve is less than a preset value. Alternatively, the system may also include a stem position sensor for detecting the stem position of the mode switching valve, and the control unit is configured to control the mode control valve to operate in the left position in the second operating mode when the stem of the mode switching valve is reset to a predetermined position.

8. The operation mode switching control system according to any one of claims 1 to 7, characterized in that, The mode control valve is a three-position three-way solenoid valve.

9. The operation mode switching control system according to any one of claims 1 to 7, characterized in that, The mode control valve includes a three-position four-way solenoid valve and a hydraulically controlled check valve. The first port of the three-position four-way solenoid valve is the oil inlet, the second port is the oil return port, the third port is connected to the forward-flowing oil inlet end of the hydraulic control check valve, and the fourth port is connected to the hydraulic control end of the hydraulic control check valve; the oil outlet end of the hydraulic control check valve is the control port. When the three-position four-way solenoid valve is in the left position, the first oil port and the third oil port are connected; when it is in the middle position, the first oil port is cut off; and when it is in the right position, the first oil port and the fourth oil port are connected, and the second oil port and the third oil port are connected.

10. An excavator having an operation mode switching control system according to any one of claims 1 to 9.

Images