CN115638161A - Hydraulic control system capable of avoiding unexpected action - Google Patents
Hydraulic control system capable of avoiding unexpected action Download PDFInfo
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- CN115638161A CN115638161A CN202110817258.0A CN202110817258A CN115638161A CN 115638161 A CN115638161 A CN 115638161A CN 202110817258 A CN202110817258 A CN 202110817258A CN 115638161 A CN115638161 A CN 115638161A
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Abstract
A hydraulic control system comprising: the action command element is used for inputting a desired actuator action command; a safety locking element in a locked state or an unlocked state; a main valve which controls the hydraulic pump to supply hydraulic oil to the actuator; and a controller that controls a valve position of the main valve based on an action command from the action command element and a state of the safety lock element; wherein, in the action start phase, upon receipt of an action command by the action command element, if the safety lock element is not previously placed in the unlocked state, the controller places the main valve in the home position by prohibiting energization to the main valve solenoid to cut off the supply of the hydraulic oil from the hydraulic pump to the actuator; and in the action ending phase, the controller detects the current in the main valve solenoid after receiving the action ending instruction, and if the current in the main valve solenoid is not lower than a preset value after a preset time period, the controller cuts off the current in the main valve solenoid forcibly.
Description
Technical Field
The present application relates to a hydraulic control system capable of avoiding unintended operation of an actuator.
Background
In hydraulic systems, the supply of hydraulic fluid to an actuator is often controlled by different valve positions of a solenoid valve, thereby controlling the actuation of the actuator. The valve position of the electromagnetic valve is controlled by the electrification and the outage of an electromagnetic coil of the electromagnetic valve. Due to software and hardware reasons of the hydraulic control system, unintended actions of the actuator may occur. For example, the actuator may begin to act in a state where the safety lockout element is locked. Further, after the end of the actuation command input, the solenoid valve spool is slowly actuated due to the residual current in the solenoid, and the actuator cannot immediately end the actuation. Further, after a command for action zeroing is input, a long reverse current may occur in the solenoid coil on the opposite side, and thus the spool may be unintentionally moved in the reverse direction, resulting in reverse action of the actuator, which is harmful to the operator and the surrounding equipment.
Disclosure of Invention
The present application is directed to providing a hydraulic control scheme that avoids unintended actuation of an actuator.
According to an aspect of the present application, there is provided a hydraulic control system including:
a motion command element arranged to be operable by an operator to input a desired actuator motion command;
a safety locking element arranged to be operable by an operator to be in a locked state or an unlocked state;
a main valve configured to control the hydraulic pump to supply hydraulic oil to the actuator; and
a controller configured to control a valve position of the main valve based on an action command from the action command element and a state of the safety lock element;
wherein, the valve position control of the controller comprises an action starting stage and an action finishing stage:
in the action starting phase, when an action command is received by the action command element, if the safety locking element is not previously placed in the unlocking state, the controller places the main valve in a home position by prohibiting the energization of the main valve solenoid to cut off the supply of the hydraulic oil to the actuator from the hydraulic pump; and is
In the action end phase, the controller detects the current in the main valve solenoid after receiving an action end instruction, and if the current in the main valve solenoid is not lower than a preset value after a predetermined period of time has elapsed, the controller forcibly cuts off the current in the main valve solenoid.
In one embodiment, in the motion initiation phase, upon receipt of a motion command by the motion command element, if the safety lockout element is in a lockout state and then placed in an unlocked state, the controller maintains the main valve in place by disabling energization of the main valve solenoid.
In one embodiment, the main valve comprises two side electromagnetic coils, when any one side electromagnetic coil is electrified, the main valve is placed at a corresponding working valve position, so that the actuator acts along a corresponding direction;
wherein, in an action end phase of the actuator in the first direction, the controller detects the current in the first side electromagnetic coil after receiving the action end command, and if the current in the first side electromagnetic coil is not lower than a first threshold value after a first predetermined period after the action end command has elapsed, the controller zeroes the current in the first side electromagnetic coil.
In one embodiment, the controller sets the currents in both the first side solenoid coil and the second side solenoid coil to zero if the current in the first side solenoid coil is not lower than the first threshold after a first predetermined period of time after the end-of-motion command has elapsed during the end-of-motion phase of the actuator in the first direction.
In one embodiment, in an end-of-stroke phase of the actuator in the first direction, the controller detects the current in the second side electromagnetic coil after receiving an end-of-stroke command, and if the current in the second side electromagnetic coil is not lower than a second threshold after a second predetermined period of time has elapsed after the end-of-stroke command, the controller zeroes the current in the second side electromagnetic coil.
In one embodiment, in the end-of-stroke phase of the actuator in the first direction, the controller detects the current in the second side electromagnetic coil if the current in the first side electromagnetic coil is lower than a first threshold after a first predetermined period of time after the end-of-stroke command has elapsed, and zeroes the current in the second side electromagnetic coil if the current in the second side electromagnetic coil is not lower than a second threshold after a second predetermined period of time after the end-of-stroke command has elapsed.
In one embodiment, in the end-of-stroke phase of the actuator in the second direction, the controller detects the current in the second side electromagnetic coil after receiving the end-of-stroke command, and if the current in the second side electromagnetic coil is not lower than the first threshold after a third predetermined period of time has elapsed after the end-of-stroke command, the controller sets the current in the second side electromagnetic coil to zero.
In one embodiment, in the end-of-motion phase of the actuator in the second direction, the controller detects the current in the first side solenoid coil after receiving the end-of-motion command, and if the current in the first side solenoid coil is not lower than the second threshold after a fourth predetermined period of time has elapsed after the end-of-motion command, the controller sets the current in the first side solenoid coil to zero.
In one embodiment, the first direction is a forward direction of the actuator, and the first direction is a reverse direction of the actuator;
optionally, the first time period is equal to the third time period;
optionally, the second time period is equal to the fourth time period;
optionally, the second time period is longer than the first time period;
optionally, the fourth time period is longer than the third time period.
In one embodiment, the first and second thresholds are set to 0mA, respectively, or to the minimum current that causes the actuator to actuate, or between 0mA and the minimum current that causes the actuator to actuate, and optionally the first and second thresholds are adjustable.
According to the hydraulic control scheme of the present application, in a state where the safety lock element is not unlocked, the solenoid valve is prohibited from being switched from the static valve position to the operating valve position based on the operation command from the operation command element. Further, if there is a current in the solenoid during a set period of time after the action command element is reset to zero, the solenoid current is forcibly cut off. Therefore, unexpected action of the actuator can be ensured, and the safety of the hydraulic system is improved.
Drawings
Embodiments of the present application will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a schematic illustration of a hydraulic control system according to an exemplary embodiment of the present application;
FIG. 2 is a flowchart of a control flow executed in the hydraulic control system of the present application;
fig. 3 to 5 are graphs explaining respective steps of the hydraulic control flow of the present application.
Detailed Description
The present application relates generally to a hydraulic control scheme that may be applied to various hydraulic systems. The hydraulic control scheme is described herein with reference to the hydraulic system schematically illustrated in fig. 1, but it will be appreciated that the hydraulic control scheme is equally applicable to other forms of hydraulic systems.
As shown in fig. 1, the hydraulic system includes a hydraulic pump 1 that supplies hydraulic oil to a hydraulic cylinder 2 to drive the operation of the hydraulic cylinder 2. In the present example, a single-acting hydraulic cylinder 2 is shown and described as an example of a hydraulic actuator, but other types of actuators, such as hydraulic motors, double-acting hydraulic pumps, etc., may also be driven here.
The operation of the hydraulic pump 1 to supply hydraulic oil to the hydraulic cylinder 2 is controlled by the hydraulic control system of the present application. The hydraulic control system mainly comprises a controller 3, an action command element 4, a safety locking element 5 and a main valve 6.
A motion command element 4, such as an operation handle, is used for inputting a desired motion command of the actuator 2 by an operator. The motion command element 4 typically has a plurality of motion positions, each motion position representing a desired speed of motion of the actuator 2. For example, a zero position represents a desired actuator 2 stop and a 100% motion position represents a desired actuator 2 motion at maximum speed. Furthermore, the position of the movement command element 4 may also be related to the desired direction of movement of the actuator 2, for example the first direction (+) movement 100% position represents the desired maximum forward speed of the actuator 2 and the second direction (-) movement 100% position represents the desired maximum reverse speed of the actuator 2. The action positions between zero and 100% represent a desire for the actuator 2 to act at a speed below the maximum speed.
A safety locking element 5, such as a safety handle or button, is used to be manipulated by the operator to enable or disable the controller 3 from executing input commands from the action command element 4. When the safety lock member 5 is in the lock position, the controller 3 prohibits the operation of the hydraulic cylinder 2 regardless of whether the operation command member 4 has an input command. When the safety lock element 5 is in the unlocked position, the controller 3 detects the position of the motion command element 4 to determine the motion command input by the operator, and allows the hydraulic cylinder 2 to perform corresponding motion by controlling the valve position of the main valve 6 upon receiving the input command from the motion command element 4.
In this example, the main valve 6 is a three-position four-way solenoid directional valve having three valve positions controlled by two control ports a, B. Each control end is provided with a corresponding electromagnet and a return spring. The valve position of the main valve 6 is switched by energizing and deenergizing the electromagnetic coil of the electromagnet of the main valve 6. When any one of the two control terminals a, B of the main valve 6 is energized, the solenoid on the other side remains de-energized.
It will be appreciated that other forms of solenoid operated directional valves may be used herein to achieve the desired functionality.
The controller 3 is connected to the operation command element 4, the safety lock element 5, and the control ends a and B of the main valve 6, and controls the valve position of the main valve 6 and the operation of the hydraulic cylinder 2 by controlling the on/off of the solenoids at the control ends a and B of the main valve 6 based on the input command of the operation command element 4 and the state of the safety lock element 5. The controller 3 may also control the operation of the pump 1, including controlling the displacement of the pump 1 based on the position of the motion command element 4, wherein the displacement of the pump 1 determines the speed of motion of the hydraulic cylinder 2.
When the action command element 4 is in the zero position, the controller 3 powers off the electromagnetic coils at the control ends A and B, the main valve 6 is in the original position, all oil ports of the main valve 6 are cut off, and the hydraulic cylinder 2 is stopped.
When the action command element 4 is moved from the zero position to the first direction position, if the safety locking element 5 is in the unlocking state, the controller 3 energizes the electromagnetic coil of the control end a, the main valve 6 is switched to the first working valve position, the oil inlet of the main valve 6 is communicated with the first working oil port, the oil drain port is communicated with the second working oil port, the output hydraulic oil of the hydraulic pump 1 is supplied to the rodless cavity of the hydraulic cylinder 2 through the oil inlet of the main valve 6 and the first working oil port, the hydraulic oil in the rod cavity of the hydraulic cylinder 2 flows back to the oil tank through the second working oil port of the main valve 6 and the oil drain port, and thus, the cylinder rod of the hydraulic cylinder 2 advances.
On the other hand, when the operation command element 4 is moved from the zero position to the second direction position, if the safety locking element 5 is in the unlocking state, the controller 3 energizes the solenoid coil of the control end B, the main valve 6 is switched to the second working valve position, the oil inlet of the main valve 6 is communicated with the second working oil port, the oil drain port is communicated with the first working oil port, the output hydraulic oil of the hydraulic pump 1 is supplied to the rod chamber of the hydraulic cylinder 2 through the oil inlet of the main valve 6 and the second working oil port, the hydraulic oil in the rodless chamber of the hydraulic cylinder 2 flows back to the oil tank through the first working oil port and the oil drain port of the main valve 6, and thus, the cylinder rod of the hydraulic cylinder 2 is retracted.
It is to be noted that the safety locking element 5 is used to allow or prohibit the main valve 6 to be switched from the home position to the operating valve position, thereby allowing or prohibiting the action of the hydraulic cylinder 2. Thus, when the action command member 4 is displaced from the zero position to the first or second directional position, if the safety lock member 5 is in the locked state, the controller 3 inhibits the energization of the solenoids of the control terminals a and B; even if the safety lock element 5 is subsequently switched to the unlock position, the controller 3 keeps prohibiting the solenoids of the control terminals a and B from being energized.
It should be noted that the hydraulic system may include a plurality of hydraulic actuators, such as hydraulic actuators for the boom, the arm, and the bucket of the excavator, respectively. In such a case, each actuator may be provided with a corresponding action command element and a main valve, and a common controller may be used to control a common hydraulic pump to supply hydraulic oil to the respective actuators via the corresponding main valves. A single safety locking element may allow or prohibit switching of all main valves from the home position to the working position, thereby allowing or prohibiting actuation of each actuator.
One example of a control flow executed by the hydraulic control system of the present application is schematically shown in fig. 2, and includes various steps described below.
In step S1, the control flow is started.
Next, in step S2, after the controller 3 confirms that the operator has input the start operation command by detecting that the operation command member 4 is out of the zero position, it checks whether the safety lock member 5 has been in the unlock state in advance. Step S3 is performed if the security locking element 5 has not been in the unlocked state first (i.e. is in the locked state at this time), and step S4 is performed if the security locking element 5 has been in the unlocked state first.
In step S3, the controller 3 sets 0 to both the currents of the solenoids at both side control ends of the main valve 6 (cuts off the current supply to the solenoids at both side control ends). Thereafter, it goes to step S8 to end the control flow, or it goes back to step S1 to cyclically execute the control flow.
In step S4, the controller 3 controls energization of the solenoid of one control end of the main valve 6 based on the motion command from the motion command element 4 to extend or retract the rod of the hydraulic cylinder 2; the controller 3 then detects the return to zero action of the action command element 4 and de-energises the solenoid of the said one control end of the main valve 6. It then goes to step S5.
In step S5, the controller 3 detects whether the current in the solenoid coil at the side control end of the main valve 6 is smaller than a preset value (e.g., zero) in a first preset time period after the action command element 4 is reset to zero. If it is detected that the current in the side solenoid is smaller than the preset value (e.g., zero), the process goes to step S6. If it is detected that the current in the side solenoid coil is equal to or greater than the preset value, the process goes to step S3.
In step S6, the controller 3 detects whether the current in the solenoid coil at the other side control end of the main valve 6 is smaller than a preset value (e.g., zero) within a second preset time period after the action command element 4 is reset to zero. If it is detected that the current in the other side solenoid coil is smaller than the preset value (e.g., zero), it goes to step S8 to end the control flow, or it goes back to step S1 to cyclically execute the control flow. If it is detected that the current in the other side solenoid coil is equal to or greater than the preset value, it goes to step S7.
In step S7, the controller 3 sets the current of the solenoid of the other side control end of the main valve 6 to 0 (turns off the solenoid of the other side control end). Thereafter, it goes to step S8 to end the control flow, or it goes back to step S1 to cyclically execute the control flow.
The first preset time period and the second preset time period may be equal or different.
The above steps S2 to S7 are further explained below with reference to fig. 3 to 5, in which the horizontal axis represents time.
Referring to fig. 3, the situation in the above step S2 → S3 is illustrated, wherein the upper half of fig. 3 represents the action curve CA of the action command element 4 and the action curve L of the safety locking element 5, and the lower half represents the current IA in the solenoid of the control end a of the main valve 6. The motion command element 4 represented by the motion curve CA is moved to the first directional position. However, the operating curve L of the safety locking element 5 indicates that, when the operating command element 4 is moved into the first direction position, the safety locking element 5 is in the locked position, and therefore the controller 3 inhibits the energization of the solenoid of the control terminal a. Even if the subsequent safety lock element 5 is switched to the unlock position, the controller 3 keeps prohibiting the energization of the solenoid of the control terminal a. In this way, the current IA in the solenoid at the control end a of the main valve 6 is kept at 0.
It will be appreciated that when the motion command element 4 is moved from the zero position to the second directional position, the controller 3 also inhibits energisation of the solenoid of the control end B of the main valve 6 if the safety locking element 5 is in the locked position.
Referring to fig. 4, the situation of the above step S4 → S5 → S3 is shown, wherein the upper part of fig. 4 represents the action curve CA of the action command element 4, and the lower part represents the current IA in the solenoid coil of the control end a of the main valve 6. As represented by the action curve CA, in the state in which the safety locking element 5 is already in the unlocked position, the action command element 4 is moved from the zero position to the first direction position at time t1 and reaches the desired first direction position (for example the +100% position, or the position less than + 100%) at time t 2. The first directional position is then maintained. Then, at time t3, the movement from the first orientation position to the zero position is started, and at time t4, the zero position is reached. In accordance with the above-described respective points in time, as shown in the current IA curve, the current IA starts increasing at time t1, reaches the rated value at time t2, and thereafter is substantially maintained at the rated value. At time t3, current IA begins to decrease. When the controller 3 detects that the current IA is not lower than the preset value (tending to decrease to 0 as the rule indicated by the dotted line after the time t 5) at the time t5 after the preset time period Δ tA is started at the time t4, the controller 3 forcibly turns off the solenoid at the control end a of the main valve 6 to forcibly decrease the current therein to 0. During the time that the solenoid of control terminal a is on/off, the solenoid of control terminal B remains off.
It will be appreciated that the solenoid on-off control for control terminal B is the same as that described above for control terminal a. That is, if the current in the solenoid at the control end B of the main valve 6 does not decrease below the preset value after a preset time period Δ tB after the movement command element 4 moves back from the second directional position to the zero position, the controller 3 also forcibly turns off the solenoid at the control end B of the main valve 6 to forcibly decrease the current therein to 0.Δ tB may be equal to or different from Δ tA, for example, Δ tB may be set larger than Δ tA, considering that the return motion of the actuator (e.g., the hydraulic cylinder 2) is generally slower than the forward motion.
Referring to fig. 5, the case of the above step S5 → S6 → S7 is shown, wherein the upper part of fig. 5 represents the action curve CA of the action command element 4, the middle part represents the current IA in the solenoid of the control end a of the main valve 6, and the lower part represents the current IB in the solenoid of the control end B of the main valve 6. As is indicated by the action curve CA, in the state in which the safety locking element 5 is first in the unlocked position, the action command element 4 is moved from the zero position to the first direction position at time t1, reaches the desired first direction position at time t2, then maintains the first direction position and starts moving from the first direction position to the zero position at time t3, and reaches the zero position at time t 4. As shown in the current IA curve, the current IA starts increasing at time t1, reaches the rated value at time t2, and then is maintained at the rated value. At time t3, the current IA starts to decrease, and at time t5 after the preset time period Δ tA starts to elapse at time t4, the current IA decreases to 0.
While controlling the current IA in the control-side a solenoid, the controller 3 also monitors the current IB in the control-side B solenoid, in particular after time t3 or t 4. At times t1 to t4, the current IB remains 0. However, after time t4, the controller 3 monitors that the current IB in the solenoid at control terminal B rises suddenly. This current, which briefly occurs in the solenoid coil on the other side during the time the solenoid coil on one side is de-energized, is referred to as a reverse current or kickback current. If the controller 3 detects at time t6 after a preset time period Δ tB' has elapsed since time t4 that the reverse current IB is still present and not below the first threshold (tending towards the continuation of the law as indicated by the dashed line after time t6 and then decreasing to 0), the controller 3 forcibly opens the solenoid of the control end B of the main valve 6, forcing the current therein to decrease to 0.Δ tB' may be equal to or different from Δ tA, Δ tB.
It is to be understood that the monitoring and control of the reverse current in the solenoid of the control terminal a for the solenoid power-off control of the control terminal B is the same as described above for the monitoring and control of the reverse current in the solenoid of the control terminal B for the solenoid power-off control of the control terminal a. That is, if the reverse current appearing in the solenoid coil at the control end a of the main valve 6 does not decrease below the second threshold value after a preset time period Δ tA' after the movement command element 4 moves back from the second direction position to the zero position, the controller 3 also forcibly turns off the solenoid coil at the control end a of the main valve 6 to forcibly reduce the reverse current therein to 0.Δ tA 'may be equal to or different from Δ tA, Δ tB'.
The first and second thresholds may each be set to 0mA, or to the minimum current that causes the actuator to actuate, or between 0mA and the minimum current that causes the actuator to actuate. And the first threshold and the second threshold are preferably adjustable, and may be equal or different.
In summary, the hydraulic control scheme of the present application includes safety measures to avoid unintended actions by the actuators.
First, when an operator inputs an operation command via the operation command element, if the safety lock element has not been placed in the unlocked state before, the main valve is held in the home position, and the supply of the hydraulic fluid to the actuator is blocked, whereby the actuator is prohibited from operating, and even after the operator inputs an operation command via the operation command element, the safety lock element is placed in the unlocked state. By this safety measure, it is possible to avoid the actuator being accidentally activated.
Next, after the actuator is actuated by energizing the main valve side solenoid, if the operator returns the action command element to zero, it is then detected whether or not the current in the side solenoid is reduced to 0 within a preset time period. If not, the current in the one-side electromagnetic coil is forced to be reduced to 0 (the one-side electromagnetic coil is turned off). By this safety measure, a quick end of the action of the actuator can be ensured. Further, if the current in the electromagnetic coil on the one side has decreased to 0 for a preset time period, it is detected whether or not there is a reverse current in the electromagnetic coil on the other side. If there is a reverse current, the current in the other side solenoid coil is forced to decrease to 0 (the other side solenoid coil is turned off). By this safety measure it is ensured that no accidental actuation of the actuator takes place.
The above-described safety measures may be used in combination with other additional safety measures for a particular hydraulic system.
Although the present application has been described herein with reference to particular embodiments, the scope of the present application is not intended to be limited to the details shown. Various modifications may be made to these details without departing from the underlying principles of the application.
Claims (10)
1. A hydraulic control system comprising:
a motion command element (4) arranged to be operable by an operator to input a desired actuator motion command;
a safety locking element (5) arranged to be operable by an operator to be in a locked state or an unlocked state;
a main valve (6) arranged to control the hydraulic pump (1) to supply hydraulic oil to the actuator; and
a controller (3) configured to control a valve position of the main valve based on an action command from the action command element and a state of the safety lock element;
wherein, the valve position control of controller includes action start phase and action end phase:
in the action starting phase, when an action command is received by the action command element, if the safety locking element is not previously placed in the unlocking state, the controller places the main valve in a home position by prohibiting the energization of the main valve solenoid to cut off the supply of the hydraulic oil to the actuator from the hydraulic pump; and is
In the action end phase, the controller detects the current in the main valve solenoid after receiving an action end instruction, and if the current in the main valve solenoid is not lower than a preset value after a predetermined period of time has elapsed, the controller forcibly cuts off the current in the main valve solenoid.
2. The hydraulic control system of claim 1, wherein in the actuation initiation phase, upon receipt of an actuation command by the actuation command element, if the safety lockout element is in a locked state and subsequently placed in an unlocked state, the controller maintains the main valve in place by disabling energization of the main valve solenoid.
3. A hydraulic control system as claimed in claim 1 or 2 wherein the main valve includes a two-sided solenoid, wherein on energisation of either side solenoid the main valve is placed in the respective operating valve position such that the actuator acts in the respective direction;
wherein, in an action end phase of the actuator in the first direction, the controller detects the current in the first side electromagnetic coil after receiving the action end command, and if the current in the first side electromagnetic coil is not lower than a first threshold value after a first predetermined period after the action end command has elapsed, the controller zeroes the current in the first side electromagnetic coil.
4. A hydraulic control system as claimed in claim 3, wherein, in the end-of-actuation phase of the actuator in the first direction, the controller sets the currents in the first and second side solenoid coils to zero if the current in the first side solenoid coil is not lower than the first threshold value after a first predetermined period of time has elapsed after the end-of-actuation command.
5. The hydraulic control system of claim 3, wherein in an end-of-stroke phase of the actuator in the first direction, the controller detects the current in the second side solenoid after receiving the end-of-stroke command, and if the current in the second side solenoid is not lower than a second threshold after a second predetermined period of time has elapsed after the end-of-stroke command, the controller zeroes the current in the second side solenoid.
6. The hydraulic control system according to claim 3, wherein in the end-of-stroke phase of the actuator in the first direction, the controller detects the current in the second side solenoid if the current in the first side solenoid is lower than a first threshold after a first predetermined period of time has elapsed after the end-of-stroke command, and zeroes the current in the second side solenoid if the current in the second side solenoid is not lower than a second threshold after a second predetermined period of time has elapsed after the end-of-stroke command.
7. The hydraulic control system according to any one of claims 3 to 6, wherein in an end-of-stroke phase of the actuator in the second direction, the controller detects the current in the second side electromagnetic coil after receiving the end-of-stroke command, and if the current in the second side electromagnetic coil is not lower than the first threshold value after a third predetermined period of time after the end-of-stroke command has elapsed, the controller sets the current in the second side electromagnetic coil to zero.
8. The hydraulic control system according to claim 7, wherein in an end-of-actuation phase of the actuator in the second direction, the controller detects the current in the first side solenoid coil after receiving the end-of-actuation command, and if the current in the first side solenoid coil is not lower than the second threshold value after a fourth predetermined period of time has elapsed after the end-of-actuation command, the controller zeroes the current in the first side solenoid coil.
9. The hydraulic control system of claim 8, wherein the first direction is a forward direction of the actuator and the first direction is a reverse direction of the actuator;
optionally, the first time period is equal to the third time period;
optionally, the second time period is equal to the fourth time period;
optionally, the second time period is longer than the first time period;
optionally, the fourth time period is longer than the third time period.
10. A hydraulic control system as claimed in claim 5, 6, 8 or 9, wherein the first and second thresholds are set to 0mA, or to the minimum current to cause actuation of the actuator, or between 0mA and the minimum current to cause actuation of the actuator, respectively, and are optionally adjustable.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110817258.0A CN115638161A (en) | 2021-07-20 | 2021-07-20 | Hydraulic control system capable of avoiding unexpected action |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110817258.0A CN115638161A (en) | 2021-07-20 | 2021-07-20 | Hydraulic control system capable of avoiding unexpected action |
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