TWI822499B - Control method and system for hydraulic drive device - Google Patents

Abstract

The present invention is a control method and system for a hydraulic drive device. The hydraulic drive device includes a motor drive device, an electric motor, a hydraulic pump and at least one hydraulic cylinder. The hydraulic pump is connected to the hydraulic cylinder through a hydraulic pipeline; Among them, a controller executes the control method of the present invention to control the hydraulic drive device. The control method includes a slow start phase, a hydraulic cylinder action phase and a slow closing phase. In the slow start phase, the controller commands the electric motor to maintain a relatively low speed to save power; in the hydraulic cylinder action phase, the controller increases or decreases the electric motor in a timely manner based on the detected changes in the total hydraulic pressure. The rotation speed maintains sufficient pressure in the hydraulic pipeline and saves the power consumption of the electric motor; during the slow closing stage, the controller commands the electric motor to gradually slow down and stop, avoiding the back electromotive force generated by the instantaneous shutdown.

Description

Control method and system for hydraulic drive device

The present invention relates to a hydraulic control device, and in particular, to a control system and method that can save power consumption of a hydraulic drive device.

Hydraulic technology is widely used in people's daily lives. It can be used in various types of mechanical equipment, production equipment, etc. Taking heavy equipment as an example, hydraulic oil will be pressurized by a hydraulic pump and sent to an actuator. The actuator is allowed to produce the required action, such as controlling a robotic arm to produce the required clamping, movement, etc.

The power source to drive the hydraulic pump can be an engine or an electric motor. In an engine-driven hydraulic system, the engine speed can be controlled based on the data detected in the hydraulic pipeline. For example, when the hydraulic pressure value is low , will immediately increase the engine speed to reach a sufficient pressure value. However, such repeated operations of turning the engine on and off will increase the fuel consumption of the engine. It not only consumes a lot of energy, but also creates serious environmental problems such as air pollution. The pressure changes experienced by the hydraulic oil in the pipeline are also very large. Violent.

On the other hand, if an electric motor is used as the power source to drive a hydraulic pump, taking the hydraulic pump used in engineering vehicles as an example, the above-mentioned problem of frequent on and off operation is still not solved. When the hydraulic pressure value is detected to be low, the speed of the electric motor will be directly increased to achieve a sufficient pressure value. Such a control method of frequently turning on and off will cause the electric motor's speed to be quickly increased and consume serious power. The hydraulic pressure changes drastically, causing the power output of the hydraulic cylinder to be unstable.

In view of this, the present invention proposes a control method for a hydraulic drive device, which enables the pressure of the hydraulic pump to change in a relatively gentle manner, maintains stable power of the hydraulic cylinder, and saves the consumption of the electric motor that drives the hydraulic pump. Electricity.

In order to achieve the foregoing object of the invention, there is a control method for a hydraulic drive device of the present invention. The hydraulic drive device includes a motor drive device, an electric motor, a hydraulic pump and at least one hydraulic cylinder. The hydraulic pump is connected to the hydraulic drive through a hydraulic pipeline. Cylinder, wherein the control method is executed by a controller and includes the following steps: when the hydraulic drive device turns on the power, the controller receives a total hydraulic pressure detected from the hydraulic pipeline, and determines the total hydraulic pressure When it is less than a preset reference hydraulic value, a slow-start motor control command is output to the motor drive device, so that the motor drive device controls the electric motor to maintain operation at a basic speed; the controller determines that a hydraulic cylinder operation has been received When commanding, a motor control command corresponding to the hydraulic cylinder operation command is output to the motor drive device, so that the motor drive device controls the electric motor to increase to a corresponding operating speed; the controller outputs the motor control command corresponding to the hydraulic cylinder operation command. After the motor control command, a control valve command is output after a preset period of delay to control the hydraulic cylinder to start operating; during the operation of the hydraulic cylinder, the controller immediately outputs a speed increase based on the current total hydraulic pressure. Or a motor control command for deceleration is given to the motor drive device to dynamically adjust the working speed of the electric motor; when the controller determines that a shutdown signal is received, it outputs a motor control command for shutdown to the motor drive device. , causing the motor driving device to gradually reduce the operating voltage provided to the electric motor and slowly turn off the electric motor.

Through the aforementioned method, the present invention provides a slow start mechanism when the power is turned on, allowing the electric motor to operate at a relatively low base speed to save power and gradually establish a base hydraulic pressure. When the controller receives the hydraulic cylinder operation command output by the user and controls the corresponding hydraulic cylinder to act, the controller continuously monitors the total hydraulic pressure and dynamically increases/decreases the speed of the electric motor in a timely manner to make the hydraulic pipeline Maintain sufficient pressure value and save power consumption of the electric motor. During the slow closing stage, the electric motor will not stop instantaneously, avoiding the high-voltage impact of reverse electromotive force and ensuring the stability and safety of the system.

100:Hydraulic drive device

10: Motor drive device

20: Electric motor

30:Hydraulic pump

31:Control valve

40: Sensor group

41: Pressure sensor

42:Temperature sensor

51:Heavy duty hydraulic cylinder

52:Light load hydraulic cylinder

200:Controller

rpm: motor speed

P: total hydraulic pressure

T: Hydraulic oil temperature

S1: Motor control command

S2: Control valve command

Figure 1: Block diagram of the control system of the hydraulic drive device of the present invention.

Figure 2: Flow chart of the control method of the hydraulic drive device of the present invention.

Figure 3: Schematic signal waveform diagram of the control method of the present invention applied to control a heavy-duty hydraulic cylinder.

Figure 4: Schematic signal waveform diagram of the control method of the present invention applied to control a heavy-load hydraulic cylinder and a light-load hydraulic cylinder.

The present invention is widely used in various types of hydraulic application fields. For example, it can be applied to various engineering vehicles that require the use of hydraulic pressure, such as garbage trucks, cement mixer trucks, or injection molding machines and stamping equipment that require the use of stamping principles. Please refer to Figure 1. The control system of the present invention includes a hydraulic drive device 100 and a controller 200. The hydraulic drive device 100 has a motor drive device 10, an electric motor 20, a hydraulic pump 30, and a sensor. The controller 200 is used to control the hydraulic drive device 100.

The motor driving device 10 is electrically connected to the electric motor 20 and provides a working voltage to control a motor speed rpm of the electric motor 20. When the working voltage is higher, the motor speed rpm increases; conversely, when the working voltage is low, Motor speed rpm drops.

The electric motor 20 provides power to drive the hydraulic pump 30 to operate, thereby controlling the rotation speed of the hydraulic pump 30 . The oil suction port and oil outlet of the hydraulic pump 30 are connected to hydraulic pipelines. A plurality of control valves 31 with different functions are provided on the hydraulic pipeline according to requirements. These control valves 31 include but are not limited to, for example, pressure control valves, flow control valves, etc. Control valves, directional control valves, etc. are used to control the pressure, flow or movement direction of hydraulic oil respectively. The hydraulic oil in the hydraulic pipeline can push at least one hydraulic cylinder 51, 52. The following description of this article takes a heavy-load hydraulic cylinder 51 and a light-load hydraulic cylinder 52 as an example, but is not limited to this number or type.

The sensor group 40 includes one or more sensors for detecting status information of the hydraulic oil. In this embodiment, the sensor group 40 includes a pressure sensor 41 and a temperature sensor 42. The pressure sensor 41 is used to detect the total hydraulic pressure P, and the temperature sensor 42 is used to detect the total hydraulic pressure P. Detect the temperature T of the hydraulic oil; in one embodiment, the pressure sensor 41 is disposed at the oil outlet of the hydraulic pump 30 to sense the total hydraulic pressure P. The temperature sensor 42 can be disposed on the hydraulic pipe. Any position in the road to sense the temperature T of the hydraulic oil.

The controller 200 is electrically connected to the motor driving device 10, the sensor group 40 and the control valves 31. The controller 200 can output a motor control command S1 to the motor driving device 10 to cause the motor to drive The device 10 controls the motor speed rpm of the electric motor 20 according to the motor control command S1; and the controller 200 also receives the hydraulic oil status information measured from the sensor group 40, such as receiving the information measured from the pressure sensor 41. The total hydraulic pressure P and the hydraulic oil temperature T measured by the temperature sensor 42; the controller 200 also outputs control valve instructions to each control valve 31, thereby controlling the actuation of the hydraulic cylinders 51 and 52.

The control method of the present invention can be implemented through the above-mentioned system architecture. Please refer to Figure 2, which is a flow chart of the control method of the present invention. Generally speaking, it includes an initial slow start phase, a hydraulic cylinder action phase and a slow closing phase. , the specific steps of each stage are explained as follows:

Slow start phase S21:

S21: After starting up, the controller 200 receives the status information of the hydraulic oil detected by the sensor group 40, where the status information of the hydraulic oil includes the total hydraulic pressure P and the hydraulic oil temperature T, and determines that the total hydraulic pressure P is less than When a preset reference hydraulic pressure value is reached, a slow-start motor control command S1 is output to the motor driving device 10 so that the motor driving device 10 controls the electric motor 20 to maintain operation at a basic rotation speed. Because when the system is initially started, the total hydraulic pressure P has not yet reached the reference hydraulic value, the controller 200 controls the electric motor 20 to start slowly to gradually increase the total hydraulic pressure P, so that the electric motor 20 can be maintained at the basic speed, thereby saving money. Electricity.

Hydraulic cylinder action stage S22~S24:

S22: The controller 200 determines whether a hydraulic cylinder operation command input by the user is received. If so, the controller 200 outputs a motor control command S1 corresponding to the hydraulic operation command to the motor driving device 10, and the motor driving device 10. Control the speed of the electric motor 20 to increase the motor speed rpm to the required working speed; wherein, according to different hydraulic cylinder operation commands input by the user, the controller 200 can output corresponding motor control commands S1 respectively, so as to Obtain the corresponding motor speed rpm. For example, if the hydraulic cylinder operation command input by the user is used to start the heavy-duty hydraulic cylinder 51, the corresponding motor control command S1 can drive the electric motor 20 to generate a higher operating speed, To provide a relatively high total hydraulic pressure P. On the contrary, if the hydraulic cylinder operation command input by the user is used to start the light-load hydraulic cylinder 52, the corresponding motor control command S1 can drive the electric motor 20 to generate a lower pressure. Working speed to provide relatively low total hydraulic pressure P.

S23: After delaying a preset period of time T _d , the controller 200 outputs the control valve command S2 corresponding to the hydraulic operation signal to the relevant control valve 31, causing the corresponding hydraulic cylinders 51, 52 to start operating; it delays after the motor control command S1 The preset period T _d is to ensure that the total hydraulic pressure P is sufficient, and then the control valve command S2 is output to control the operation of the hydraulic cylinders 51 and 52 to allow the hydraulic cylinders 51 and 52 to operate when the pressure is sufficient.

S24: During the operation of the hydraulic cylinders 51 and 52, the controller 200 continues to receive the total hydraulic pressure P measured from the pressure sensor 41 and the hydraulic oil temperature T measured from the temperature sensor 42. The controller 200 The current total hydraulic pressure P is continuously monitored, and the motor speed rpm is appropriately dynamically adjusted according to the total hydraulic pressure P. The following uses two different embodiments to illustrate how to control the motor speed rpm based on the total hydraulic pressure P.

In the first preferred embodiment, the controller 200 determines whether the measured total hydraulic pressure P is lower than a preset lower limit of working pressure. Because when the hydraulic cylinders 51 and 52 start to operate, the total hydraulic pressure P will drop from an original target pressure value. If the drop is too large, it may affect the power output of the hydraulic cylinders 51 and 52. The target pressure value is Refers to the pressure value required to operate the hydraulic cylinders 51 and 52. The target pressure value is greater than the aforementioned reference pressure value. The required target pressure value can be set separately for different hydraulic cylinders 51 and 52. For example, heavy load The target pressure value of the hydraulic cylinder 51 can be greater than the target pressure value of the light-load hydraulic cylinder 52. When the hydraulic cylinders 51 and 52 are operating, if the monitored total hydraulic pressure P drops below or equal to the lower limit of the working pressure. At this time, the controller 200 outputs the motor control command S1 to the motor driving device 10 to increase the operating speed of the electric motor 20 again, so that the total hydraulic pressure P gradually returns to the target pressure value. For example, if the target pressure value is set to 200kg/cm ² and the lower limit of the working pressure is set to 160kg/cm ² , when the hydraulic cylinders 51 and 52 start to operate, once the total hydraulic pressure P drops to the preset working pressure When the lower limit value is 160kg/cm ² , the controller 200 outputs a motor control command S1 to increase the rotation speed to the motor drive device 10 so that the total hydraulic pressure can be restored to the target pressure value of 200kg/cm ² .

In the second preferred embodiment, the controller 200 calculates a pressure difference ΔP between the sensed total hydraulic pressure P and the target pressure value, and adjusts the electric motor 20 according to the pressure difference ΔP. The adjustment range of the working speed. When the pressure difference ΔP is larger, the electric motor 20 is increased to run at a relatively higher speed; when the pressure difference ΔP is smaller, the electric motor 20 is controlled to run at a relatively lower speed. For example, The electric motor 20 can reach the target pressure value of 200kg/cm ² when running at 200rpm. When the controller 200 calculates that the pressure difference ΔP is 160kg/cm ² , it controls the electric motor 20 to run at 2000rpm; when the pressure difference ΔP When P decreases to 80kg/cm ² , the rotation speed of the electric motor 20 is controlled to decrease to 800rpm.

On the other hand, when the controller 200 detects that the total hydraulic pressure P continues to decrease or is even lower than a preset abnormal lower limit value, such as lower than 10kg/cm ² , it means that there may be a hydraulic oil leakage problem. At this time, The controller 200 outputs a motor control command S1 for speed reduction to the motor drive device 10 to reduce the rotation speed of the electric motor 20 to avoid the risk of oil leakage, where the abnormal lower limit value will be lower than the working pressure lower limit value.

In terms of temperature monitoring, when the controller 200 determines whether the hydraulic oil temperature T measured by the temperature sensor 42 is higher than an upper temperature limit, if so, the controller 200 outputs a motor control command S1 for speed reduction to the motor. The driving device 10 is used to reduce the rotation speed of the electric motor 20 .

Slow closing phase S25:

S25: When the controller 200 receives a shutdown signal input by the user, the controller 200 outputs a motor control command S1 for shutdown to the motor driving device 10 . After receiving the motor control command S1, the motor driving device 10 does not immediately interrupt the power supply to the electric motor 20, but adopts a gradual slow shutdown to gradually reduce the operating voltage provided to the electric motor 20 to control the motor speed. The rpm gradually decreases, so the electric motor 20 will not stop momentarily, and the generation of a huge reverse electromotive force can be avoided.

In order to more clearly illustrate the initial slow start phase, hydraulic cylinder action phase and slow closing phase of the control method of the present invention, Figure 3 takes the control of a heavy-load hydraulic cylinder as an example. The period from t0 to t1 is the initial slow start phase, and the controller 200 After the system is started up, when it is determined that the total hydraulic pressure P is less than a preset reference hydraulic pressure value of 200kg/ ^cm2 , a slow-start motor control command S1 is output to the motor drive device 10 to control the motor speed rpm to gradually increase and maintain operation at A basic speed of 400rpm.

At time t1, after receiving a hydraulic cylinder operation command input by the user, the controller 200 outputs a motor control command S1 corresponding to the hydraulic operation command to the motor driving device 10. The motor driving device 10 increases the pressure of the electric motor 20. Rotate to 800rpm. Between t1 and t2 is a delayed preset period T _d . The controller 200 outputs the control valve command S2 to the relevant control valve 31 at time t2, thereby controlling the heavy-duty hydraulic cylinder 51 to start operating.

During the operation period t2~t3 of the heavy-duty hydraulic cylinder 51, the controller 200 continues to monitor the total hydraulic pressure P and the hydraulic oil temperature T. When the total hydraulic pressure P is lower than a lower working pressure limit of 160kg/cm ² (Fig. (not shown), the controller 200 will output the motor control command S1 to the motor driving device 10 to increase the operating speed of the electric motor 20 to 1600 rpm again, until the total hydraulic pressure P returns to the reference hydraulic pressure value of 200kg/cm ² , then it will decrease. The speed of the electric motor 20 reaches a base speed of 400rpm.

At time t3, the controller 200 receives a shutdown signal input by the user, and the controller 200 outputs a motor control command S1 for shutting down the hydraulic system to the motor driving device 10. After receiving the motor control command S1, the motor driving device 10 gradually reduces the operating speed of the electric motor 20 until it completely stops.

The various pressure values and rotational speed values in the above examples are only for illustration and do not limit the numerical range used in the present invention.

Please refer to another example shown in FIG. 4 , which takes the control of a heavy-load hydraulic cylinder 51 and a light-load hydraulic cylinder 52 as an example. The actions from t0 to t3 are the same as those explained in FIG. 3 , so they will not be described again. The difference is that at time t4, after the controller 200 receives the user's input of a hydraulic cylinder operation command corresponding to the light-load hydraulic cylinder 52, the controller 200 outputs a motor control command S1 corresponding to the hydraulic operation command to the motor driving device 10 , the motor driving device 10 slightly reduces the working speed of the electric motor 20 to make it slightly lower than the motor speed under heavy load, and the corresponding total hydraulic pressure P will also be slightly lower than the pressure value under heavy load, but it can still Ensure that the light-load hydraulic cylinder 52 can operate normally. At time t5, the controller 200 receives a closing signal input by the user, and the controller 200 outputs a motor control command S1 for closing to the motor driving device 10. According to the motor control command S1, the motor driving device 10 gradually reduces the operating speed of the electric motor 20 until it completely stops.

To sum up, in the slow start phase of the present invention, the controller allows the electric motor to run at a relatively low basic speed to save power, and first establishes a basic oil pressure value to avoid subsequent hydraulic cylinder action phases. The power surge and power burden caused by the rapid increase from zero to the target pressure value. During the hydraulic cylinder action phase, the controller dynamically increases or decreases the electric motor speed appropriately based on the detected total hydraulic pressure and the current load status. During the slow closing stage, the electric motor will not cause instantaneous stop problems, avoid high-voltage impact of reverse electromotive force, and ensure the stability and safety of the system.

In the overall control process, when the electric motor speed drops to 50%, the flow rate of hydraulic oil also drops to 50%. However, the power consumed by an electric motor is proportional to the cube of the motor speed rpm. When the motor speed drops to 50%, the power consumption will be significantly reduced to 12.5%. Overall, since the electric motor of the present invention does not continuously maintain a high speed and does not undergo frequent on/off control, the pressure change of the total hydraulic pressure can be slowly reduced, and the power consumption can also be reduced.

Claims (10)

A control method for a hydraulic drive device, wherein the hydraulic drive device includes a motor drive device, an electric motor, a hydraulic pump and at least one hydraulic cylinder, and the hydraulic pump is connected to the hydraulic cylinder through a hydraulic pipeline; the control method It is executed by a controller and includes the following steps: when the hydraulic drive device is powered on, the controller receives a total hydraulic pressure detected from the hydraulic pipeline and determines that the total hydraulic pressure is less than a preset reference hydraulic pressure. When the value is reached, a slow-start motor control command is output to the motor driving device, so that the motor driving device controls the electric motor to maintain operation at a basic speed; when the controller determines that a hydraulic cylinder operation command is received, it outputs the corresponding hydraulic pressure A motor control command of the cylinder operation command is given to the motor drive device, so that the motor drive device controls the electric motor to increase to a corresponding operating speed; after the controller outputs the motor control command corresponding to the hydraulic cylinder operation command, it is delayed After a preset period of time, a control valve command is output to control the hydraulic cylinder to start operating; during the operation of the hydraulic cylinder, the controller immediately outputs a motor control command to increase or decrease the speed based on the current total hydraulic pressure. The motor driving device is used to dynamically adjust the working speed of the electric motor; when the controller determines that a shutdown signal is received, it outputs a motor control instruction for shutdown to the motor driving device, so that the motor driving device gradually Reduce the operating voltage provided to the electric motor to slowly shut down the electric motor. The control method of a hydraulic drive device as described in claim 1, wherein in the step of the controller immediately outputting a motor control command to increase or decrease the operating speed of the motor to the motor drive device, the controller is further: When it is judged that the measured total hydraulic pressure is lower than or equal to a lower limit of working pressure, the controller immediately outputs a motor control command for speed increase to the motor driving device to increase the working speed of the electric motor; and When it is judged that the measured total hydraulic pressure has returned to a target pressure value, the controller immediately outputs a motor control command for speed reduction to the motor drive device, where the target pressure value is the pressure required for the operation of the hydraulic cylinder. , the target pressure value is greater than the base pressure value. The control method of a hydraulic drive device as described in claim 1, wherein in the step of the controller immediately outputting a motor control command to increase or decrease the operating speed of the motor to the motor drive device, the controller is further: Calculate a pressure difference between the sensed total hydraulic pressure and a target pressure value, and determine the adjustment range of the operating speed of the electric motor according to the pressure difference, wherein the target pressure value is determined by the operation of the hydraulic cylinder The required pressure at the time, the target pressure value is greater than the basic pressure value; when the pressure difference is larger, the electric motor is controlled to operate at a higher operating speed; when the pressure difference is smaller, the electric motor is controlled to operate at a lower operating speed working speed. The control method of a hydraulic drive device according to any one of claims 1 to 3, wherein the controller further receives a hydraulic temperature detected from the hydraulic pipeline, and when it is determined that the hydraulic temperature is higher than a temperature above When the limit value is reached, the controller outputs a motor control command for speed reduction to the motor drive device to reduce the speed of the electric motor. The control method of a hydraulic drive device as described in any one of claims 1 to 3, wherein when the controller determines that the total hydraulic pressure is lower than a preset abnormal lower limit value, the controller outputs a speed reduction signal. The motor control command is given to the motor drive device to reduce the speed of the electric motor. The control method of a hydraulic drive device as described in any one of claims 1 to 3, wherein in the step of the controller outputting the motor control command to the motor drive device, the controller is based on the load state of the hydraulic cylinder. , output the motor control command corresponding to the load state, so that the electric motor generates the operating speed corresponding to the load state. The control method of a hydraulic drive device as claimed in claim 1, wherein the total hydraulic pressure is measured through a pressure sensor provided at the oil outlet of the hydraulic pump. As claimed in claim 4, the control method of a hydraulic drive device, wherein the hydraulic temperature is measured through a temperature sensor disposed on the hydraulic pipeline. The control method of a hydraulic drive device as claimed in claim 1, wherein the control valve command is used to control a plurality of control valves provided in the hydraulic pipeline, and the hydraulic cylinder is controlled by opening or closing the control valves. . A control system for a hydraulic drive device, including: a hydraulic drive device, including: a motor drive device, electrically connected to an electric motor, the motor drive device provides a working voltage to control a motor speed of the electric motor; a hydraulic The pump is driven by the electric motor, wherein the hydraulic pump is connected to at least one hydraulic cylinder through a hydraulic pipeline; and a pressure sensor is used to detect the hydraulic system of the hydraulic oil in the hydraulic pipeline. pressure; a controller electrically connected to the motor drive device and the pressure sensor, wherein the controller executes the control method of the hydraulic drive device as described in any one of claims 1 to 9.

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