Variable speed control system and control method for a quantitative pump of an electric excavator

Abstract

The application provides a variable speed control system and control method of an electric excavator constant flow pump, comprising: a whole machine controller, a motor controller, a motor, a constant flow pump and a battery; the whole machine controller is used for sending a control instruction to the motor controller; the motor controller is used for receiving the control instruction sent by the whole machine controller, obtaining electric energy from the battery, modulating through a self inverter, outputting current and voltage to the motor to make the motor rotate; the motor combines the constant flow pump to form a power source for supplying oil to a load sensitive multi-way valve system of the excavator; the device adopts the motor variable speed drive constant flow pump to form the power source for supplying oil to the load sensitive multi-way valve, cancels the load pressure feedback pipeline from the load sensitive multi-way valve to the pump, and fully gives play to the advantages of the motor in speed regulation accuracy, speed regulation response time and speed regulation stability.

Description

Technical Field

[0001] This invention relates to a variable speed control system and control method for a fixed displacement pump in an electric excavator, belonging to the field of excavator control technology. Background Technology

[0002] Pure electric excavator systems are zero-carbon emission drive systems, aligning with the national goal of low-carbon and green development. They can effectively alleviate resource scarcity and air pollution, and the electrification of construction machinery is rapidly developing. However, current pure electric excavators simply replace engines with electric motors, fixing the speed at a constant value and having only one constant power point. They fail to develop specialized control strategies for the power system based on the hydraulic system, thus not fully utilizing the advantages of electric motors in speed regulation accuracy, response time, and stability. This results in low overall machine efficiency and a poor user experience; furthermore, they fail to leverage the advantages of electric motors in short-term overload operation under high-power loads. Summary of the Invention

[0003] The purpose of this invention is to provide a variable speed control system and method for a fixed displacement pump in an electric excavator. By replacing the traditional motor plus plunger pump with a motor plus a fixed displacement pump, the advantages of the motor in terms of speed regulation accuracy, speed regulation response time, and speed regulation stability are fully utilized.

[0004] To achieve the above objectives / to solve the above technical problems, the present invention is implemented using the following technical solution.

[0005] On one hand, the present invention provides a variable speed control system for a fixed displacement pump in an electric excavator, comprising: a machine controller, a motor controller, a motor, a fixed displacement pump, and a battery;

[0006] The overall controller is used to send control commands to the motor controller;

[0007] The motor controller is used to receive control commands sent by the vehicle controller, obtain electrical energy from the battery, and output current and voltage to the motor after modulation by its own inverter, so as to make the motor rotate.

[0008] The motor, combined with a metering pump, forms a power source used to supply oil to the excavator's load-sensitive multi-way valve system;

[0009] The battery is used to provide electrical energy to the motor controller.

[0010] Furthermore, it also includes: a pressure sensor, which is used to acquire the outlet pressure P of the metering pump. p and maximum load pressure P Lmax It is then transmitted to the overall controller to provide control commands for adjusting the motor's operating speed.

[0011] Secondly, the present invention provides a control method for the above-described electric excavator fixed displacement pump variable speed control system, comprising the following steps:

[0012] Calculate the set power P of the fixed displacement pump based on the maximum output power of the motor and the maximum discharge power Ps of the battery. Pset ;

[0013] According to the set power P of the metering pump Pset Calculate the pressure inflection point of the corresponding gear of the metering pump by combining the predetermined speed of the metering pump and the displacement of the metering pump.

[0014] Based on the set power of the fixed displacement pump and the maximum load pressure P Lmax And the displacement of the fixed displacement pump, and calculate the target speed of the motor for the corresponding gear;

[0015] When the maximum load pressure P Lmax When the pressure is less than the pressure inflection point of the corresponding gear of the metering pump, the pressure is determined according to the outlet pressure P of the metering pump. p and maximum load pressure P Lmax The motor operating speed is adjusted in real time according to the pressure difference between them;

[0016] When the maximum load pressure P Lmax When the pressure inflection point of the corresponding gear of the fixed displacement pump is greater than the pressure inflection point, the motor operating speed is the target speed of the corresponding gear.

[0017] Furthermore, the maximum output power of the motor is determined as follows:

[0018] When the current temperature of the motor controller is T mc Temperature less than the upper limit of normal operation of the motor controller (T) mcmax Current motor temperature T mo Less than the upper limit temperature of normal operation of the motor T momax When the battery SOC exceeds the battery SOC threshold, the maximum output power of the motor is equal to the instantaneous power P of the motor controller. MCS ;

[0019] Otherwise, the maximum output power of the motor is equal to the rated operating power P of the motor controller. MCL .

[0020] Furthermore, the method for obtaining the set power of the metering pump is as follows:

[0021] Maximum output power of motor and maximum discharge power of battery P s The smaller of the two values ​​is used to set the power;

[0022] Among them; the maximum discharge power of the battery P s The specific method for obtaining it is as follows:

[0023] Calculate the battery's maximum discharge power based on its state of charge (SOC).

[0024] Furthermore, the expression for calculating the pressure inflection point of the corresponding gear of the metering pump based on the set power of the metering pump, the predetermined speed of the metering pump gear, and the displacement of the metering pump is as follows:

[0025] ;

[0026] in: This is the pressure inflection point for a metering pump. The set power of the metering pump, Preset the speed for the corresponding gear of the fixed displacement pump. This refers to the displacement of a fixed-displacement pump.

[0027] Furthermore, the method of combining the set power of the metering pump with the maximum load pressure P Lmax And the expression for calculating the target speed of the motor at the corresponding gear, based on the displacement of the fixed displacement pump, is as follows:

[0028] ;

[0029] in: The target speed of the motor. For maximum load pressure, The set power of the metering pump, This refers to the displacement of a fixed-displacement pump.

[0030] Furthermore, based on the outlet pressure P of the fixed displacement pump p and maximum load pressure The motor operating speed is adjusted in real time according to the pressure difference between them, specifically:

[0031] When the pressure difference ΔP is less than the set pressure difference ΔP set The lower limit is determined by the overall controller increasing the motor speed with a gradient Δn.

[0032] When the pressure difference ΔP is greater than the set pressure difference ΔP set The upper limit is reached, and the overall controller reduces the motor speed with a gradient Δn.

[0033] The gradient Δn is calculated as follows:

[0034] ;

[0035] in: The system speed gradient of the load-sensitive multi-way valve system under no-load conditions. For the load-sensitive multi-way valve system, the pilot pressure is given by x, where x is the speed gradient correction factor. The pilot pressure at which the valve port opens corresponds to the action of the load-sensitive multi-way valve system. To achieve the pilot pressure required for the maximum differential pressure of the load-sensitive multi-way valve system, Set the maximum speed gradient for the load-sensitive multi-way valve system;

[0036] Where: the pressure difference ΔP is set. set The calculation method is as follows:

[0037] ;

[0038] in: Set the differential pressure for the load-sensitive multi-way valve system when it is unloaded. For the load-sensitive multi-way valve system, the pilot pressure is given by k, where k is the differential pressure correction factor, and P is the pilot pressure. o P is the pilot pressure when the valve port opens in a load-sensitive multi-way valve system. imax To achieve the pilot pressure required for the maximum differential pressure of the load-sensitive multi-way valve system, Set the maximum differential pressure for the load-sensitive multi-way valve system.

[0039] The set pressure difference ΔP set The adjustment method for gradient Δn is as follows:

[0040] Reduce the set pressure difference ΔP when operating at low speed and low flow rate. set and gradient ;

[0041] In motor start-up and acceleration scenarios, increase the set pressure difference ΔP. set and gradient ;

[0042] When operating at high speed and high flow rate, increase the set pressure difference ΔP. set and gradient .

[0043] Furthermore, under no-load conditions in a load-sensitive multi-way valve system, when the load pressure... When the time interval between zero and zero is greater than T1 and less than T2, the motor operates at the set minimum speed.

[0044] When the load pressure P Lmax When the time interval is zero or greater than or equal to T2, the motor's operating speed is zero.

[0045] Wherein: T 1、 T2 is the preset motor idling time, and T1 < T2.

[0046] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The present invention uses a variable speed motor to drive a fixed displacement pump as a power source to supply oil to a load-sensitive multi-way valve, replacing the traditional motor plus plunger pump, giving full play to the advantages of the motor in speed regulation accuracy, speed regulation response time and speed regulation stability; it can effectively improve the comfort and stability of operation and enhance the driver's driving experience.

[0047] This invention develops a specialized control strategy for the power system based on the hydraulic system. The system pressure difference and constant power point can be adaptively adjusted, and the advantages of the motor in short-term overload operation when encountering high power loads are also utilized, which can improve the safety and economy of the whole vehicle. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the hydraulic system principle of the present invention;

[0049] Figure 2 To set up the power flow chart;

[0050] Figure 3 This is a schematic diagram of the motor control of the present invention;

[0051] Figure 4 This is a flowchart of the idle speed control process. Detailed Implementation

[0052] It should be noted that:

[0053] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solution of the present invention, rather than limitations thereof. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0054] The term "and / or" simply describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. Additionally, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0055] Example 1

[0056] like Figure 1 The embodiment shown provides a variable speed control system for a fixed displacement pump in an electric excavator, including: a machine controller 1, a motor controller 2, a motor 3, a fixed displacement pump 4, and a battery;

[0057] The overall controller 1 is electrically connected to the motor controller 2, and the motor controller 2 is electrically connected to the motor 3. The output shaft of the motor 3 is connected to the fixed displacement pump 4. The first connection point of the fixed displacement pump 4 is connected to the oil tank to draw oil from the tank, and the second connection point of the fixed displacement pump 4 is connected to the pressure reducing valve 5. The hydraulic oil output by the fixed displacement pump 4 is supplied to the pilot handle 6 after passing through the pressure reducing valve 5. After receiving the two hydraulic oil outputs from the pressure reducing valve 5, the pilot handle 6 inputs the two hydraulic oils to two throttle ports 7 through hydraulic pipelines to control the size of the throttle ports 7. The two throttle ports 7 are connected to the pressure compensation valve 8 through hydraulic pipelines. The pressure compensation valve 8 outputs hydraulic oil to the corresponding actuator 9 to perform the corresponding action. The actuator 9 and the pressure compensation valve 8... A shuttle valve 10 is connected between the components; a first pressure sensor is connected to the third connection point of the metering pump 4, which collects the outlet pressure of the metering pump 4 and transmits it to the whole machine controller 1 via electrical hardwire; the fourth connection point of the metering pump 4 is connected to the overflow valve 11, which realizes the overflow function when the system exceeds the flow rate; a second pressure sensor and a third pressure sensor are connected to the pilot handle 6, which collect the pilot pressure of the left handle and the right handle respectively, and transmit it to the whole machine controller 1 via electrical hardwire; the fourth pressure sensor is connected to the shuttle valve 10 and the overflow valve through the hydraulic pipeline, collects the maximum load pressure, and transmits it to the whole machine controller 1 via electrical hardwire. The whole machine controller 1 is used to send control commands to the motor controller 2.

[0058] The motor controller 2 is used to receive control commands sent by the vehicle controller, obtain electrical energy from the battery, and output current and voltage to the motor 3 after modulation by its own inverter, so that the motor 3 can rotate.

[0059] The motor 3, combined with the metering pump 4, forms a power source for supplying oil to the load-sensitive multi-way valve system of the excavator.

[0060] The battery is used to provide electrical energy to the motor controller 2.

[0061] It also includes: a pressure sensor, which is used to acquire the outlet pressure P of the metering pump 4. p and maximum load pressure P Lmax It is then transmitted to the main controller 1 to control the speed of motor 3.

[0062] Example 2

[0063] like Figures 2-4 As shown, this embodiment provides a control method based on the above-described electric excavator fixed displacement pump variable speed control system, including the following steps:

[0064] Step 1: Calculate the set power P of the fixed displacement pump based on the maximum output power of the motor and the maximum discharge power Ps of the battery. Pset Specifically, it includes:

[0065] Step 1.1: The method for determining the maximum output power of the motor is as follows:

[0066] When the current temperature of the motor controller is T mc Temperature less than the upper limit of normal operation of the motor controller (T) mcmax Current motor temperature T mo Less than the upper limit temperature of normal operation of the motor T momax When the battery SOC exceeds the battery SOC threshold, the maximum output power of the motor is equal to the instantaneous power P of the motor controller. MCS ;

[0067] Otherwise, the maximum output power of the motor is equal to the rated operating power P of the motor controller. MCL .

[0068] Step 1.2: Maximum battery discharge power P s The method for obtaining it is as follows:

[0069] Calculate the maximum discharge power of the battery based on its State of Charge (SOC).

[0070] Step 1.3: The method for obtaining the set power of the metering pump is as follows:

[0071] Maximum output power of motor and maximum discharge power of battery P s The smaller value between the two is used to set the power.

[0072] Step 2: According to the set power P of the metering pump Pset Based on the predetermined speed and displacement of the corresponding gear of the fixed displacement pump, the pressure inflection point of the corresponding gear is calculated. The expression for the pressure inflection point is:

[0073] ;

[0074] in: This is the pressure inflection point for a metering pump. The set power of the metering pump, Preset the speed for the corresponding gear of the fixed displacement pump. This refers to the displacement of a fixed-displacement pump.

[0075] Step 3: Based on the set power of the metering pump and the maximum load pressure P Lmax In addition to the displacement of the fixed displacement pump, the target speed of the motor at the corresponding gear is calculated. The expression for the target speed is:

[0076] ;

[0077] in: The target speed of the motor. For maximum load pressure, The set power of the metering pump, This refers to the displacement of a fixed-displacement pump.

[0078] Step 4: When the maximum load pressure P Lmax When the pressure is less than the pressure inflection point of the corresponding gear of the metering pump, the pressure is determined according to the outlet pressure P of the metering pump. p and maximum load pressure P Lmax The pressure difference ΔP between them is adjusted in real time to control the motor speed.

[0079] When the maximum load pressure P Lmax When the pressure exceeds the inflection point of the corresponding gear of the fixed displacement pump, the motor operating speed is the target speed of the corresponding gear, specifically including:

[0080] When the pressure difference ΔP is less than the set pressure difference ΔP set The lower limit is determined by the overall controller increasing the motor speed with a gradient Δn.

[0081] When the pressure difference ΔP is greater than the set pressure difference ΔP set The upper limit is reached, and the overall controller reduces the motor speed with a gradient Δn.

[0082] Where: Calculate the set pressure difference ΔP set The expression is:

[0083] ;

[0084] in: Set the differential pressure for the load-sensitive multi-way valve system when it is unloaded. For the load-sensitive multi-way valve system, the pilot pressure is given by k, where k is the differential pressure correction factor, and P is the pilot pressure. o P is the pilot pressure when the valve port opens in a load-sensitive multi-way valve system. imax To achieve the pilot pressure required for the maximum differential pressure of the load-sensitive multi-way valve system, Set the maximum differential pressure for the load-sensitive multi-way valve system.

[0085] The gradient Δn is calculated as follows:

[0086] ;

[0087] in: The system speed gradient of the load-sensitive multi-way valve system under no-load conditions. For the load-sensitive multi-way valve system, the pilot pressure is given by x, where x is the speed gradient correction factor. The pilot pressure at which the valve port opens corresponds to the action of the load-sensitive multi-way valve system. To achieve the pilot pressure required for the maximum differential pressure of the load-sensitive multi-way valve system, Set the maximum speed gradient for the load-sensitive multi-way valve system;

[0088] Wherein: the set pressure difference ΔP set The adjustment method for gradient Δn is as follows:

[0089] Reduce the set pressure difference ΔP when operating at low speed and low flow rate. set and gradient ;

[0090] In motor start-up and acceleration scenarios, increase the set pressure difference ΔP. set and gradient ;

[0091] When operating at high speed and high flow rate, increase the set pressure difference ΔP. set and gradient .

[0092] Step 5: Under no-load conditions of the load-sensitive multi-way valve system, when the load pressure... When the time between zero and zero is greater than T1 and less than T2, the motor operates at the set minimum speed. When the load pressure P... Lmax When the time interval is greater than or equal to T2, the motor's operating speed is zero, where: T 1、 T2 is the preset motor idling time, T1 <T2。

[0093] Example 3

[0094] This embodiment provides a method for controlling the variable speed of a fixed displacement pump in an electric excavator.

[0095] This includes: the controller collects the battery's SOC, and then the controller obtains the battery's maximum discharge power Ps by looking up a table. Since the battery's discharge capacity is different when the SOC is different, the larger the battery's SOC, the stronger the battery's discharge capacity and the greater the discharge power.

[0096] When the current temperature of the motor controller is less than 90℃, the current temperature of the motor is less than 100℃, and the battery SOC is greater than 30%, the maximum output power of the motor is equal to the instantaneous power P of the motor controller. MCS Otherwise, the maximum output power of the motor is the rated operating power P of the motor controller. MCL .

[0097] Maximum output power of motor and maximum discharge power of battery P s The smaller of the two values ​​is used as the set power P. Pset .

[0098] The set power of the metering pump Combined with the predetermined speed of the fixed displacement pump gear and the displacement of the metering pump Calculate the pressure inflection point of the corresponding gear of the fixed displacement pump. The expression is as follows:

[0099] ;

[0100] The set power of the metering pump Combined with maximum load pressure P Lmax and the displacement of the metering pump The expression for calculating the target speed of the motor at the corresponding gear. Specifically:

[0101] ;

[0102] When the machine is first started and has not yet moved, the motor runs at the predetermined speed of the corresponding gear. When the operator operates the handle and the maximum load pressure P... Lmax The pressure inflection point is less than the corresponding gear of the metering pump. At this time, based on the outlet pressure P of the metering pump p and maximum load pressure P Lmax The motor speed is adjusted in real time according to the pressure difference between the two sides. When the pressure difference ΔP is less than the set pressure difference ΔP, the motor speed is adjusted accordingly. set The lower limit is reached when the controller increases the motor speed by a gradient Δn, and the pressure difference ΔP is greater than the set pressure difference ΔP. set The upper limit of the speed is reached, and the whole machine controller reduces the motor speed with a gradient Δn.

[0103] Set the pressure difference ΔP and the speed gradient ΔP set The pressure changes according to the handle pilot signal. When the handle pilot pressure is less than the pilot pressure at the corresponding valve port opening of the load-sensitive multi-way valve system, the pressure difference ΔP is set. set Both the gradient Δn and the pressure difference ΔP are too small. When the pilot pressure of the handle is greater than the pilot pressure at which the corresponding valve port of the load-sensitive multi-way valve system opens, the pressure difference ΔP is set. set The gradient Δn increases with the lead pressure of the handle, where the maximum upper limits are respectively... and At this time, the motor speed will be adjusted in real time, when the pressure difference ΔP is at ΔP set The lower limit and ΔP set Set the pressure difference ΔP between the upper and lower limits. set Since the gradient Δn no longer changes, the motor speed also no longer changes, and it operates at the existing speed.

[0104] When the maximum load pressure P Lmax The pressure inflection point is greater than the corresponding gear of the fixed displacement pump. The motor operates at the target speed corresponding to the gear. run.

[0105] When the whole machine is in no-load condition, the load pressure When the time between zero and zero is greater than T1 and less than T2, the motor operates at the set minimum speed. When the load pressure P... Lmax When the time interval is zero or greater than or equal to T2, the motor's operating speed is zero.

[0106] This invention uses a variable-speed electric motor to drive a fixed-displacement pump as a power source to supply oil to a load-sensitive multi-way valve, replacing the traditional electric motor and plunger pump. This fully leverages the advantages of electric motors in speed regulation accuracy, speed regulation response time, and speed regulation stability, effectively improving the comfort and stability of operation and enhancing the driver's driving experience.

[0107] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for controlling the variable speed of a fixed displacement pump in an electric excavator, applied to a variable speed control system for a fixed displacement pump in an electric excavator, characterized in that, The system includes: a whole machine controller, a motor controller, a motor, a metering pump, and a battery; The overall controller is used to send control commands to the motor controller; The motor controller is used to receive control commands sent by the vehicle controller, obtain electrical energy from the battery, and output current and voltage to the motor after modulation by its own inverter, so as to make the motor rotate. The motor, combined with a metering pump, forms a power source used to supply oil to the excavator's load-sensitive multi-way valve system; The battery is used to provide electrical energy to the motor controller; The method includes the following steps: calculating the set power P of the metering pump based on the maximum output power of the motor and the maximum discharge power Ps of the battery. Pset ; According to the set power P of the metering pump Pset Calculate the pressure inflection point of the corresponding gear of the metering pump by combining the predetermined speed of the metering pump and the displacement of the metering pump. Based on the set power of the fixed displacement pump and the maximum load pressure P Lmax And the displacement of the fixed displacement pump, and calculate the target speed of the motor for the corresponding gear; When the maximum load pressure P Lmax When the pressure is less than the pressure inflection point of the corresponding gear of the metering pump, the pressure is determined according to the outlet pressure P of the metering pump. p and maximum load pressure P Lmax The motor operating speed is adjusted in real time according to the pressure difference between them; When the maximum load pressure P Lmax When the pressure inflection point of the corresponding gear of the fixed displacement pump is greater than the pressure inflection point, the target speed of the corresponding gear shall be taken as the motor operating speed.

2. The variable speed control method for a quantitative pump in an electric excavator according to claim 1, characterized in that, Also includes: Pressure sensor, the pressure sensor being used to acquire the outlet pressure P of the metering pump. p and maximum load pressure P Lmax It is then transmitted to the overall controller to provide control commands for adjusting the motor's operating speed.

3. The variable speed control method for a quantitative pump in an electric excavator according to claim 1, characterized in that, The method for determining the maximum output power of the motor is as follows: When the current temperature of the motor controller is T mc Temperature less than the upper limit of normal operation of the motor controller (T) mcmax The current temperature of the motor is T. mo Less than the upper limit temperature of normal operation of the motor T momax When the battery SOC exceeds the battery SOC threshold, the maximum output power of the motor is equal to the instantaneous power P of the motor controller. MCS ; Otherwise, the maximum output power of the motor is equal to the rated operating power P of the motor controller. MCL .

4. The variable speed control method for a quantitative pump in an electric excavator according to claim 1, characterized in that, The method for obtaining the set power of the metering pump is as follows: Maximum output power of motor and maximum discharge power of battery P s The smaller value between the two is used to set the power.

5. The variable speed control method for a quantitative pump in an electric excavator according to claim 1, characterized in that, The expression for calculating the pressure inflection point of the corresponding gear of the metering pump based on the set power of the metering pump, the predetermined speed of the metering pump gear, and the displacement of the metering pump is as follows: ； in: This is the pressure inflection point for a metering pump. The set power of the metering pump, Preset the speed for the corresponding gear of the fixed displacement pump. This refers to the displacement of a fixed-displacement pump.

6. The variable speed control method for a quantitative pump in an electric excavator according to claim 1, characterized in that, The method is based on the set power of the metering pump combined with the maximum load pressure P. Lmax And the expression for calculating the target speed of the motor at the corresponding gear, based on the displacement of the fixed displacement pump, is as follows: ； in: The target speed of the motor. For maximum load pressure, The set power of the metering pump, This refers to the displacement of a fixed-displacement pump.

7. The variable speed control method for a quantitative pump in an electric excavator according to claim 1, characterized in that, Based on the outlet pressure P of the metering pump p and maximum load pressure The motor operating speed is adjusted in real time according to the pressure difference between them, specifically: When the pressure difference ΔP is less than the set pressure difference ΔP set The lower limit is determined by the overall controller increasing the motor speed with a gradient Δn. When the pressure difference ΔP is greater than the set pressure difference ΔP set The upper limit is reached, and the overall controller reduces the motor speed with a gradient Δn. The gradient Δn is calculated as follows: ； in: The system speed gradient of the load-sensitive multi-way valve system under no-load conditions. For the load-sensitive multi-way valve system, the pilot pressure is given by x, where x is the speed gradient correction factor. The pilot pressure at which the valve port opens corresponds to the action of the load-sensitive multi-way valve system. To achieve the pilot pressure required for the maximum differential pressure of the load-sensitive multi-way valve system, Set the maximum speed gradient for the load-sensitive multi-way valve system; Where: the pressure difference ΔP is set. set The calculation method is as follows: ； in: Set the differential pressure for the load-sensitive multi-way valve system when it is unloaded. For the load-sensitive multi-way valve system, the pilot pressure is given by k, where k is the differential pressure correction factor, and P is the pilot pressure. o P is the pilot pressure when the valve port opens in a load-sensitive multi-way valve system. imax To achieve the pilot pressure required for the maximum differential pressure of the load-sensitive multi-way valve system, Set the maximum differential pressure for the load-sensitive multi-way valve system.

8. The variable speed control method for a quantitative pump in an electric excavator according to claim 1, characterized in that, Under no-load conditions in a load-sensitive multi-way valve system, when the load pressure... When the time interval between zero and zero is greater than T1 and less than T2, the motor operates at the set minimum speed. When the load pressure P Lmax When the time interval is zero or greater than or equal to T2, the motor's operating speed is zero. Wherein: T 1、 T2 is the preset motor idling time, T1 <T2。

Images