Pure electric linear electromagnetic driving breaking hammer and control method thereof

Abstract

The invention discloses a pure electric type linear electromagnetic drive breaking hammer and a control method thereof, the pure electric type linear electromagnetic drive breaking hammer comprises a cylinder body composed of an upper cylinder body, a middle cylinder body and a lower cylinder body, and the adjacent cylinder bodies are coaxially positioned through positioning rings and are axially connected through a whole-body bolt; comprising a stator and a mover, a cylindrical cavity is formed in the middle of the stator, the mover penetrates through the cylindrical cavity, and an air gap exists between the cylindrical cavity and the mover; the middle cylinder body is fixed on a middle cylinder body driver, is connected with a power battery of the excavator through an input cable and performs information interaction with an excavator control system; the nitrogen chamber is arranged in the upper cylinder body, and the upper end of the rotor extends into the nitrogen chamber to compress internal nitrogen; the drill rod is arranged at the bottom of the lower cylinder body and connected with the lower cylinder body through a drill rod sleeve and a limiting pin, the drill rod sleeve and the lower cylinder body are fixed, the drill rod has an axial movement range, and the lower end of the rotor can hit the drill rod. The invention is suitable for crushing operations such as mining and concrete removal on engineering vehicles such as electric-driven excavators.

Description

Technical Field

[0001] This invention relates to the field of crushing machinery and equipment, and in particular to a pure electric linear electromagnetic drive breaker and its control method. Background Technology

[0002] Existing construction machinery, such as excavators, is gradually shifting from fuel-powered to pure electric drive due to factors such as economy and intelligence. Traditional hydraulic breakers used with excavators also need to be upgraded to pure electric versions.

[0003] Traditional hydraulic breakers use hydraulic energy generated by a hydraulic pump driven by an internal engine in the excavator to move a piston, achieving high-frequency reciprocating motion under the action of a directional valve. This results in problems such as complex structure, low efficiency, frequent maintenance, and poor controllability. Existing electric breakers on the market, such as electric hammers, use a rotary motor to drive a crank-slider mechanism. The slider reciprocates to compress air, creating a reciprocating impact hammer. Due to the numerous transmission links and the lack of an energy storage mechanism, the energy conversion efficiency of electric hammers is less than 50%, even lower than some hydraulic breakers.

[0004] Linear electromagnetic drive is a driving method that directly generates linear thrust through electromagnetic induction. It has a simple structure, requires no intermediate transmission mechanism, and can easily achieve high-speed motion. In recent years, with the development of high-performance rare-earth permanent magnet materials and electromagnetic drive technology, the thrust, response time, and control precision of linear electromagnetic drives have reached extremely high levels, making their application in the field of pure electric hydraulic breakers possible.

[0005] However, applying linear electromagnetic drive technology to the field of hydraulic breakers presents the following challenges: 1. Common pure electric excavators and other engineering vehicles are equipped with DC power batteries ranging from tens to hundreds of volts. The driving method of pure electric hydraulic breakers needs to be matched with the power supply and be simple and efficient.

[0006] 2. Pure electric hydraulic breakers abandon traditional hydraulic control valves and require the design of new control schemes tailored to the characteristics and control logic of linear electromagnetic mechanisms.

[0007] 3. Hydraulic breakers generally require high frequency and high impact power, which necessitates that the electromagnetic mechanism can provide sufficient electromagnetic thrust and maximum speed, but this is limited by the maximum output power. At high speeds, electromagnetic thrust drops sharply, so the electromagnetic and structural parameters of the electromagnetic mechanism need to be optimized.

[0008] 4. The high-frequency reciprocating motion of the mover requires frequent return braking. If there is no energy storage mechanism or the energy storage design is inappropriate, it will cause a significant energy loss. Summary of the Invention

[0009] The purpose of this invention is to address the shortcomings of existing technologies by proposing a pure electric linear electromagnetic drive breaker and its control method, which is suitable for crushing operations such as mining and concrete demolition on electric excavators and other engineering vehicles.

[0010] The objective of this invention is achieved through the following technical solution: a pure electric linear electromagnetic drive hydraulic breaker, the hydraulic breaker comprising: The cylinder block consists of an upper cylinder block, a middle cylinder block, and a lower cylinder block. Adjacent cylinder blocks are coaxially positioned by locating rings and axially connected by through bolts. A linear electromagnetic drive device includes a stator composed of stacked toroidal iron cores and a mover containing an excitation structure. The stator has a cylindrical cavity in the middle, through which the mover passes and there is an air gap. The drive unit, fixed to the middle cylinder block, is connected to the excavator's power battery via an input cable and interacts with the excavator's control system. The nitrogen chamber is located in the upper cylinder body, with an opening at the bottom. The upper end of the mover extends into the nitrogen chamber to compress the nitrogen inside. The chisel is located at the bottom of the lower cylinder and is connected to the lower cylinder via a chisel sleeve and a limiting pin. The chisel sleeve is fixed to the lower cylinder and has an axial range of motion. The lower end of the mover can strike the chisel.

[0011] Furthermore, the stator is composed of multiple stacked annular iron cores, with annular grooves carved between the iron cores for placing hollow disc coils. The outer side of the iron cores is provided with lead-out grooves, and the coil leads are led out and connected to each other to form a three-phase winding.

[0012] Furthermore, the excitation structure is cylindrical and fits onto the moving shaft. The moving shaft has a shoulder, which, together with the moving shaft sleeve, axially fixes the excitation structure.

[0013] Furthermore, the excitation structure is composed of annular permanent magnets and annular magnetic steels stacked axially in an alternating manner, with adjacent permanent magnets having opposite magnetization directions. This structure forms an axially periodically changing surface magnetic field. Buffer blocks are provided on the contact surfaces on both sides of the excitation structure to protect the permanent magnets, which are brittle materials.

[0014] Furthermore, the middle cylinder body includes a stator housing and stator end caps. The stator of the linear electromagnetic drive device is located inside the stator housing and fixed by two stator end caps. A displacement sensor and a temperature sensor are provided inside the middle cylinder body to detect the position and speed information of the mover and the internal temperature of the electromagnetic drive device. Each of the two stator end caps is connected to a positioning ring. Both ends of the mover pass through the entire middle cylinder body and extend out of the positioning ring. A bushing and a retaining ring are installed on the inner side of the positioning ring, which slide in cooperation with the shaft surfaces at both ends of the mover.

[0015] Furthermore, each of the two stator end caps of the middle cylinder is provided with a heat dissipation channel. One end of the heat dissipation channel is connected to the outside through a filter, and the other end is connected to the air gap between the stator and the mover. The external cooling medium enters the air gap through one heat dissipation channel, flows through the inner surface of the stator, and is discharged from the other heat dissipation channel, thereby achieving heat dissipation for the linear electromagnetic drive structure.

[0016] Furthermore, the driver is provided with a pressure signal interface on its outside, which is connected to a pressure sensor to receive pressure numerical signals; the driver is provided with a three-phase inverter circuit to convert the DC input of the power battery into a three-phase AC output. The three-phase winding coil inside the stator generates a traveling wave magnetic field that moves in a linear direction under the input of the three-phase AC power. The traveling wave magnetic field interacts with the magnetic field of the mover excitation structure to generate an axial electromagnetic thrust, driving the mover to perform axial reciprocating motion.

[0017] On the other hand, the present invention also provides a control method for a purely electric linear electromagnetic drive hydraulic breaker, the method comprising the following steps: Step S1: The hydraulic breaker is in its initial state. The chisel and the mover are pressed down to the lower limit of the stroke by gravity and the initial thrust of the nitrogen chamber, and the chisel and the mover remain in contact. Step S2: The hydraulic breaker enters the ready-to-start state. The excavator controls the hydraulic breaker to descend vertically to hold the target material to be broken. The chisel is lifted by force, and the mover moves upward together. Based on the displacement detected by the position sensor, the driver confirms that the hydraulic breaker has entered the ready-to-start state. In step S3, the hydraulic breaker performs a return lift, the driver outputs three-phase AC power, and the mover is lifted continuously by the electromagnetic thrust, detaching from the chisel and rising a set distance. During this period, the electromagnetic thrust does work against gravity and the thrust of the nitrogen chamber, which is converted into the kinetic energy of the mover, gravitational potential energy and the elastic potential energy of the gas inside the nitrogen chamber. Step S4: When the driver output current reverses, the electromagnetic thrust begins to brake downwards, and it is accelerated downwards. It continues to move upwards until the kinetic energy of the mover returns to zero, and then begins to move downwards. In step S5, the hydraulic breaker enters its stroke. The mover continues to descend and accelerate under the action of electromagnetic thrust, gravity, and nitrogen chamber thrust, reaching its maximum speed when it contacts the chisel at the top dead center. In step S6, the hydraulic breaker impacts the chisel, causing its speed to quickly return to zero. The kinetic energy is converted into impact energy and transmitted to the target material through the chisel. If the target material is not broken, the hydraulic breaker returns to step S2 and continues to operate. If the target material is broken, the driver stops supplying power until the two materials meet and lift again, entering the next impact cycle.

[0018] Furthermore, by changing the magnitude of the electromagnetic thrust, the return lifting distance, or adjusting the control strategy, different impact energy and impact frequencies can be achieved. Among them, the greater the return lifting distance, the greater the impact energy of the hydraulic breaker, but the impact frequency will decrease. The output current and power of the linear electromagnetic drive device can be increased or decreased according to the load conditions.

[0019] Furthermore, in step S3, for applications requiring greater impact power, the braking detection signal is changed from the mover displacement distance to the mover speed. After detecting that the speed has returned to zero, the driver is commanded to reverse the current and directly enter the stroke stage of step S5, enabling the hydraulic breaker to achieve maximum impact power and impact efficiency.

[0020] The beneficial effects of this invention are: 1. A linear electromagnetic drive device is used as the actuator of the pure electric breaker. The DC power battery equipped in the electric excavator is used as the power source. The three-phase AC output is realized through the inverter circuit inside the driver to drive the electromagnetic device. This system eliminates the traditional engine and hydraulic pump, and directly converts electrical energy into the kinetic energy of the mover. It can achieve extremely high energy conversion efficiency. At the same time, it has a simple structure, high unit integration, is easy to manufacture, more durable and easy to maintain.

[0021] 2. A driver control circuit, coupled with displacement sensors, air pressure sensors, and temperature sensors, is used to replace the traditional self-reversing hydraulic valve, and an electrically controlled impact process is designed based on this. This control system can not only detect key parameters such as the position and speed of the moving part, the temperature rise of the electromagnetic device, and the air pressure in the nitrogen chamber during the operation of the breaker, but also achieve different impact forces and impact frequencies according to actual working conditions by adjusting the magnitude of the electromagnetic thrust, the return lifting distance, and control strategies.

[0022] 3. By using a nitrogen chamber as the energy storage device for the return stroke, and by optimizing the rated parameters of the linear electromagnetic drive device and the proportional relationship between the electromagnetic thrust, the weight of the mover, and the thrust of the nitrogen chamber, the optimal range of motion parameters for the pure electric linear electromagnetic drive breaker was determined. This ensures that the impact power and impact frequency of the breaker meet industry standards while greatly reducing the energy consumption required for braking. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of a system scheme for a pure electric linear electromagnetic drive hydraulic breaker. Figure 2 This is a three-dimensional structural diagram of the hydraulic breaker of the present invention; Figure 3 This is an exploded view of the hydraulic breaker of the present invention; Figure 4 This is a cross-sectional view of the cylinder body of the hydraulic breaker of the present invention; Figure 5 This is a structural diagram of the linear electromagnetic drive device of the present invention; Figure 6 This is a cross-sectional view of the linear electromagnetic drive device of the present invention; Figure 7 This is a schematic diagram of the impact process of the hydraulic breaker of the present invention; Figure 8 This is a diagram showing the mechanical output characteristics of the linear electromagnetic drive device according to an embodiment of the present invention; Figure 9 This is a curve showing the change in thrust of the nitrogen chamber in an embodiment of the present invention; Figure 10 These are the velocity-time curves and velocity-displacement curves using control strategy one in this embodiment of the invention; Figure 11 These are the velocity-time curves and velocity-displacement curves using control strategy two in this embodiment of the invention. In the diagram: 1. Cylinder block; 11. Upper cylinder block; 111. Nitrogen chamber; 112. Nitrogen seal; 113. Nitrogen valve; 114. Pressure sensor; 12. Middle cylinder block; 121. Stator housing; 122. Cable outlet; 123. Stator end cover; 124. Displacement sensor; 125. Temperature sensor; 126. Heat dissipation channel; 127. Filter; 128. Filter screen; 13. Lower cylinder block; 131. Drill rod; 132. Drill rod sleeve; 133. Limit pin; 14. Positioning ring; 141. Shaft sleeve ; 142 Retaining ring; 143 Dustproof ring; 15 Through bolt; 16 Upper nut; 2 Stator; 21 Iron core; 211 Outlet slot; 22 Coil; 3 Mover; 31 Mover shaft; 32 Mover bushing; 33 Permanent magnet; 34 Magnetic steel; 35 Buffer block; 36 Sleeve; 4 Driver; 41 Input cable; 42 Pneumatic signal interface; 5 Housing; 51 Bucket shaft; 52 Housing; 53 Upper liner; 54 Lower liner; 55 Fixing bolt; 6 Power battery. Detailed Implementation

[0025] The technical solutions in the embodiments of this application will be described below with reference to the accompanying drawings. The embodiments are merely examples and do not limit the scope of application of the present invention.

[0026] The terms "connection" and "fixing" used in this document include conventional connection methods such as welding and threaded connections, without explicitly limiting the connection methods. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application.

[0027] This invention provides a pure electric linear electromagnetic drive breaker, the principle of which is as follows: Figure 1 As shown, the power battery 6 is located inside the excavator, outputting hundreds of volts of DC power, which is connected to the driver 4 located on the outside of the breaker cylinder 1 via a cable. The driver 4 contains a three-phase inverter circuit that converts the DC input into a three-phase AC output. The stator 2 is fixed inside the cylinder 1 and contains a three-phase winding composed of multiple coils 22, which generates a linearly moving traveling wave magnetic field under the three-phase AC input.

[0028] The mover 3 is located inside the stator 2. Its interior is an excitation structure composed of permanent magnet 33 and magnetic steel 34, which can form an axially periodically changing surface magnetic field. The traveling wave magnetic field interacts with the magnetic field of the mover excitation structure to generate an axial electromagnetic thrust, driving the mover 3 to perform vertical reciprocating motion.

[0029] The upper and lower ends of the cylinder 1 are provided with a nitrogen chamber 111 and a chisel 131. When the mover 3 rises, the gas inside the nitrogen chamber 111 is compressed to generate a downward thrust. When the mover 3 falls, it will impact the chisel 131 at the bottom, converting kinetic energy into impact energy and acting on the broken material held at the lower end of the chisel 131.

[0030] The chisel 131 moves up and down a short distance via the limiting pin 133. In its vertical state, it is at the lower stop point, and when it is against the broken material, it is raised to the upper stop point.

[0031] There is an air gap between the stator 2 and the mover 3. There is a heat dissipation channel 126 on each of the upper and lower sides of the cylinder body 1, which is connected to the air gap. The other end of the heat dissipation channel 126 is connected to the outside through a filter 127. The filter screen 128 inside can filter the external air. The external cooling airflow enters the air gap from the lower channel under the action of external force, flows through the inner surface of the stator and is discharged from the upper channel, thereby realizing the heat dissipation of the electromagnetic structure.

[0032] The cylinder block 1 is equipped with a position sensor 124, a temperature sensor 125 and a pressure sensor 114 to feed back motion parameters, internal temperature, nitrogen chamber pressure and other parameters to the actuator 4. The actuator 4 changes the impact parameters by adjusting the current and the stroke of the mover, or controls the cooling airflow speed to cool down in time.

[0033] The three-dimensional structure and installation method of a pure electric linear electromagnetic drive breaker are as follows: Figure 2 , Figure 3As shown, the main body of the breaker hammer consists of a cylinder 1, a stator 2, a mover 3, a driver 4, and a housing 5. The housing 5 is equipped with two bucket shafts 51 that connect to the end of the robotic arm of excavators and other construction machinery. Its housing 52 is a two-plate structure. The cylinder 1 of the breaker hammer is positioned on the inside by an upper liner 53 and a lower liner 54. Fixing bolts 55 pass through the liners and are fixed to the housing.

[0034] Cylinder block structure as follows Figure 3 As shown, the cylinder body 1 is divided into three parts: an upper cylinder body 11, a middle cylinder body 12, and a lower cylinder body 13. Two positioning rings 14 are located between adjacent cylinder bodies for coaxial positioning between the three cylinder bodies. The lower cylinder body 13 is provided with four corner threaded holes, and the other two cylinder bodies are provided with four corner through holes. The bottom of four through bolts 15 are threaded to the lower cylinder body 13, and the top ends pass through the through holes of the middle cylinder body 12 and the upper cylinder body 11 in sequence. The three cylinder bodies are axially fixed by the upper nut 16.

[0035] The overall sectional view of the hydraulic breaker cylinder 1 is as follows: Figure 4 As shown, the drill rod 131 is located in the lower cylinder 13, the stator 2 and the mover 3 form a linear electromagnetic drive device located in the middle cylinder 12, and the nitrogen chamber 111 is located in the upper cylinder 11.

[0036] The specific structure and cross-sectional view of the linear electromagnetic drive device are as follows: Figure 5 , Figure 6 As shown, the stator 2 is located inside the stator housing 121 of the middle cylinder 12, and is fixed at both ends by two stator end caps 123. The stator end caps 123 are also connected to two positioning rings 14 at both ends. The mover 3 runs through the entire interior of the middle cylinder 12, with both ends extending out of the positioning rings 14. The upper part extends into the nitrogen chamber 111 of the upper cylinder 11, and the lower part can contact the chisel 131 in the lower cylinder 13. There is an air gap between the stator 2 and the mover 3.

[0037] The stator 2 is composed of multiple toroidal iron cores 21 stacked together. An annular groove is dug between two layers of iron cores 21 to accommodate coils 22. The coils 22 are hollow disc coils. The coil wires are led out through the wire outlet grooves 211 on the outside of the iron cores 21 and connected to each other to form the three-phase winding of the stator.

[0038] The cylindrical cavity in the middle of the stator 2 is used to accommodate the mover 3, which includes a mover shaft 31, an excitation structure, and a mover shaft sleeve 32. The outer ring of the mover shaft 31 is a permanent magnet excitation structure, which is mainly composed of annular permanent magnets 33 and annular magnetic steel 34 axially interleaved and stacked, with the magnetization directions of two adjacent permanent magnets 33 being opposite, ultimately forming an axially periodically changing surface magnetic field. The excitation structure is cylindrical and fits onto the mover shaft 31, with one end abutting against the shoulder on the mover shaft 31 and the other end being axially fixed by the mover shaft sleeve 32. The contact surfaces on both sides of the excitation structure are also provided with buffer blocks 35 to protect the permanent magnets, which are brittle materials. A thin-walled sleeve 36 is provided on the outer side of the excitation structure. The sleeve 36 is made of non-magnetic materials such as stainless steel, which protects the permanent magnets 33 without affecting the magnetic field strength.

[0039] like Figure 4 As shown, each of the two stator end caps 123 of the middle cylinder block 12 has a heat dissipation channel 126. One end of the heat dissipation channel 126 is connected to the outside through a filter, and the other end is connected to the air gap between the stator 2 and the mover 3. The external cooling medium can enter the air gap through one heat dissipation channel 126, flow through the inner surface of the stator and then be discharged from the other heat dissipation channel 126 to dissipate heat from the linear electromagnetic drive structure.

[0040] The cylinder block 12 is also equipped with an integrated displacement sensor 124 and a temperature sensor 125, which are close to the stator 2 and the mover 3 and are set on both sides of the stator 2. They can detect the position and speed information of the mover 3 and the internal temperature of the electromagnetic drive device. The sensor signal line and the lead wire of the coil 22 enter the driver 4 through the outlet 122 of the stator housing 121 and are connected to the internal circuit.

[0041] The driver 4 is fixed to the side of the middle cylinder block 12 and is connected to an external power source via an input cable 41 to exchange information with the excavator control system. The driver 4 also has a pneumatic signal interface 42 on its outer side, which connects to a pneumatic sensor in the upper cylinder block to receive pneumatic pressure signals.

[0042] like Figure 4 The enlarged view of the connection between the middle cylinder 12 and the upper cylinder 11 is shown. The positioning ring 14 is located between the two adjacent cylinders and is mainly used for positioning. The bushing 141 is installed on its inner side and slides with the two ends of the moving part 3. The bushing 141 is fixed by the retaining ring 142. The retaining ring 142 has a groove on its inner side for installing the dustproof ring 143 to prevent dust from entering the middle cylinder 13.

[0043] The nitrogen chamber 111 has an opening at its bottom, through which the mover 3 extends to compress the internal nitrogen. A nitrogen seal 112 is provided on the wall of the opening, contacting the upper shaft surface of the mover 3 to prevent nitrogen leakage. The outer side of the upper cylinder block 11 also has two connecting holes communicating with the nitrogen chamber 111. One connects to the nitrogen valve 113 for replenishing nitrogen, and the other connects to the pressure sensor 114, whose signal line is connected to the pressure signal interface 42 on the outside of the driver 4 for feedback of the pressure value.

[0044] The drill rod 131 and the drill rod sleeve 132 are connected to the lower cylinder 13 through the limiting pin 133. The drill rod sleeve 132 and the lower cylinder 13 are completely fixed together, and the drill rod 131 has a certain range of axial movement.

[0045] The lifting of the mover compresses the gas in the nitrogen chamber to store energy, and the energy is released during descent, striking the bottom chisel to transfer the energy to the material being broken, thus achieving one impact motion. The impact process of this purely electric hydraulic breaker is as follows: Figure 7 As shown, the specific steps are as follows: In step S1, the hydraulic breaker is in its initial state. The chisel 131 and the mover 3 are pressed down to the lower limit of their stroke by gravity and the initial thrust of the nitrogen chamber 111, and the chisel 131 and the mover 3 remain in contact.

[0046] In step S2, the hydraulic breaker enters the ready-to-start state. The excavator controls the hydraulic breaker to descend vertically and hold the target material to be broken. The chisel 131 is lifted by force, and the moving part 3 moves upward a certain distance. The position sensor 124 detected the displacement, and the driver 4 confirmed that the breaker had entered the ready-to-start state.

[0047] In step S3, the hydraulic breaker performs a return lift, and the driver 4 outputs three-phase AC power. The mover 3, under the action of electromagnetic thrust, detaches from the chisel 131 and continues to rise. During this process, the electromagnetic thrust overcomes gravity and the thrust of the nitrogen chamber 111, converting into the kinetic energy of the mover 3, the gravitational release energy, and the elastic potential energy of the gas inside the nitrogen chamber 111. As the mover 3 continues to rise a certain distance... Then, the output current of driver 4 reverses, and the electromagnetic thrust begins to brake downwards.

[0048] In step S4, the hydraulic breaker performs a return braking maneuver. Although the moving part 3 still has upward velocity, it experiences a huge downward acceleration under the influence of electromagnetic thrust, gravity, and the thrust of the nitrogen chamber 111, and continues to move upward a certain distance. Afterwards, the kinetic energy of mover 3 returns to zero, and it begins to move downwards.

[0049] In step S5, the hydraulic breaker enters its stroke. Under the influence of electromagnetic thrust, gravity, and the thrust of the nitrogen chamber 111, the rotor 3 continues to descend and accelerates, reaching its maximum speed upon contact with the chisel 131 at the top dead center. .

[0050] In step S6, the hydraulic breaker impacts, and the moving part 3 moves at a speed of... The impact drill rod 131 rapidly reduced its speed to zero, while its kinetic energy... Converted into impact energy The material is transferred to the target material via the drill rod 131. If the target material is not broken, the breaker returns to step S2 to continue operating; if the target material is broken, the drill rod 131 and the mover 3 will move downwards to the displacement position. Next, driver 4 stops supplying power until the two come into contact and rise again, entering the next impact cycle.

[0051] To calculate the impact energy and impact frequency of a purely electric hydraulic breaker, electromagnetic thrust is used. 3-gravity of the moving part Nitrogen chamber 111 thrust kinetic friction The dynamic equations of the hydraulic breaker's rotor, constructed using Newton's second law, are as follows: Where x is the displacement distance of the mover, positive for upward and negative for downward, and represents the electromagnetic thrust. During the return stroke in step S3, the direction is upward; during the return braking and stroke phases in steps S4 and S5, the direction is downward. This is due to the linear electromagnetic drive power... There is an upper limit; when the speed of the moving part 3 is less than the rated speed... At that time, the electromagnetic thrust is constant, and is When the speed exceeds the rated speed, it enters a constant power state, and the thrust will continuously decrease, as shown in the following expression: Nitrogen chamber 111 thrust Size and compression length, gas contact area Initial volume Initial pressure thermal insulation coefficient Regarding the nitrogen chamber, the compression ratio CR has a generally applicable value of 1.1~2.5. If it is too small, the gas thrust change is not significant, and if it is too large, the temperature rise is large and the lifespan is short. The expression is as follows: For ease of calculation and comparison, the final kinetic energy of the hydraulic breaker's rotor 3 is used. Equivalent to impact energy By the law of conservation of energy, the impact energy equals the electromagnetic thrust. The positive work done during the return lift and stroke in steps S3 and S5 and Subtract the negative work done by the return braking in step S4. Subtract the friction force Negative work done in one round trip Its expression is: To ensure the impact effect matches industry requirements and achieves optimal performance, this invention uses dynamic simulation to determine some preferred parameters to optimize the impact effect. These parameters include the mechanical characteristics of the linear electromagnetic drive device, nitrogen chamber parameters, and mover operating parameters, as detailed below: Output power in linear electromagnetic drive device Rated speed Below 1.5 m / s, maximum operating speed can reach 10 m / s, rated electromagnetic thrust With an initial acceleration of 45 to 75 times the weight of the mover and 1.5 to 2.5 times the return resistance at the starting position, the mover can obtain a large initial acceleration and quickly approach the rated speed.

[0052] In the nitrogen chamber parameters, the compression ratio CR is controlled between 1.5 and 2 to avoid excessively small thrust variations or excessive temperature rise. The contact area A is calculated from the drill rod diameter to avoid excessive differences in the dimensions of the mover and the drill rod. The chamber pressure generally does not exceed 2 MPa. Adjust the above parameters so that the nitrogen chamber thrust is at the ready-to-start position. 0.4 to 0.6 times, at the maximum displacement. The displacement distance is generally no more than 1.4 times the diameter of the drill rod, which is 1.1 to 1.2 times the diameter of the drill rod.

[0053] Under the above parameter settings, the mover experiences a large acceleration and rises rapidly at the start of its return stroke. However, as the speed and displacement increase, the electromagnetic thrust decreases, the downward resistance increases, and the mover's acceleration decreases rapidly. Thus, the mover will maintain its rated speed. The speed is no more than 3 m / s in the vicinity. Due to the low return speed, the electromagnetic thrust is always kept at a high level. Most of the electrical energy is converted into the elastic potential energy of the gas in the nitrogen chamber, and the kinetic energy of the mover that needs to be offset during the return braking is greatly reduced.

[0054] Because of the low mover speed and the large thrust of the nitrogen chamber, the mover speed can quickly return to zero in a very short time and distance during the return braking phase, which greatly reduces the energy consumed by the electromagnetic drive device during braking.

[0055] During the stroke phase, most of the return energy stored in the nitrogen chamber is released, driving the mover to descend rapidly. The end-stroke speed is higher than 8 m / s but not more than 10 m / s, ensuring that while achieving a large impact power, it is still within the effective operating speed of the linear electromagnetic drive device.

[0056] This embodiment uses the specifications of a traditional 68 hydraulic breaker as a reference. Its chisel diameter is 68mm, the input hydraulic power is 11.5Kw, the impact energy is about 677J, the impact frequency is about 700bpm (number of blows per minute), and its mechanical efficiency is about 68.7%. This does not include the energy loss of the excavator's engine, hydraulic pump, hydraulic valve, and hydraulic pipeline.

[0057] Based on the impact performance of a hydraulic hammer, this embodiment provides an electromagnetic output power... This is an 11kW pure electric linear electromagnetic drive breaker, wherein the mechanical characteristics of the electromagnetic drive mechanism are as follows: Figure 8 As shown, rated thrust 9000N, rated speed Approximately 1.22 m / s.

[0058] In this embodiment, the values ​​of various parameters were selected based on the above-mentioned preferred parameters. Specifically, the compression ratio (CR) of the nitrogen chamber was set to 1.65, and the charging pressure was 1.4 MPa. The nitrogen chamber thrust curve is shown below. Figure 9 As shown, the thrust at the start-up position is 5084N, approximately 0.56 At the maximum displacement of 90 mm, the thrust is 10250 N, approximately 1.14. The moving part weighs 17 kg. Approximately 54 times the force of gravity, the return lift distance The radius is set to 80mm. The velocity-time and velocity-displacement curves of the mover are obtained through dynamic simulation, as shown below. Figure 10 As shown, the mover initially experiences a large acceleration and rises rapidly. However, as the velocity and displacement increase, the electromagnetic thrust decreases, the downward resistance increases, and the mover's acceleration decreases rapidly, causing the mover's velocity to be slightly greater than the rated velocity during the return lifting phase. However, it is less than 2 m / s. Due to the low return speed, the electromagnetic thrust remains at a high level and the mover kinetic energy is relatively low. Most of the work done by the electromagnetic thrust during the return lifting phase is converted into the gravitational potential energy of the mover and the elastic potential energy of the nitrogen chamber gas, which greatly reduces the energy loss required for return braking.

[0059] Through the above-mentioned optimized design, during the return braking phase, due to the small kinetic energy of the mover and the extremely large braking force, the mover speed quickly returns to zero within a very short time and distance, which greatly reduces the energy consumed by the electromagnetic drive device during braking. Finally, the impact energy of this embodiment reaches 717J, the impact frequency is 838bpm, the impact power is about 10kW, the average output power of the electromagnetic drive device is about 10.4kW, and the mechanical efficiency reaches 96.2%.

[0060] This embodiment can also achieve different impact energy magnitudes and impact frequencies by changing the magnitude of the electromagnetic thrust, the return lift distance, or adjusting the control logic. For example, changing the return lift distance... The work done by electromagnetic thrust is positively correlated with distance. The larger the size, the greater the impact power of the hydraulic breaker, but the lower the impact frequency, and vice versa. It can achieve both low impact power and high impact frequency. For example, by adjusting the output current and power of the electromagnetic drive device, the current and power can be increased or decreased according to the load conditions. This can meet the demand for high impact power under high load conditions, while reducing power consumption and heat generation during low load operation.

[0061] This invention also provides a control strategy for maximizing impact power. In step S3, during the return stroke, all other parameters remain unchanged, but the braking detection signal is changed from the mover displacement to the mover speed. As the resistance increases continuously during the mover's upward movement, the mover speed gradually decelerates until it reaches zero. This control method detects that the speed has reached zero and then commands the driver 4 to reverse the current. At this point, the mover directly enters the stroke stage of step S5. Under this control method, the electromagnetic drive device has no braking loss and the stroke is the longest, allowing the hydraulic breaker to achieve maximum impact power and impact efficiency. However, because the mover operates at low speed for a long time in the later stages of the return stroke, the overall impact frequency and impact power of the hydraulic breaker will be lower. This is suitable for applications requiring high impact power. Figure 11 The figure shows the speed-time curve and speed-displacement curve of the control method used in this embodiment. The impact energy reaches 825J, the impact frequency is 686bpm, the impact power is 9.43kW, and the average output power of the electromagnetic drive device is 9.63kW with an efficiency of 98%.

[0062] The above embodiments demonstrate that, while meeting or even exceeding industry requirements, pure electric linear electromagnetic drive hydraulic breakers can achieve higher mechanical efficiency and a wider adjustable range with a simpler structure, fully adapting to the new development of electric drive technology in the field of engineering machinery.

[0063] The above embodiments are only illustrative examples and do not limit their scope of protection. Any modifications or substitutions that do not exceed the spirit and essence of the present invention are within the scope of protection of the present invention.

Claims

1. A pure electric linear electromagnetic drive hydraulic breaker, characterized in that, The hydraulic breaker includes: The cylinder block consists of an upper cylinder block, a middle cylinder block, and a lower cylinder block. Adjacent cylinder blocks are coaxially positioned by locating rings and axially connected by through bolts. A linear electromagnetic drive device includes a stator composed of stacked toroidal iron cores and a mover containing an excitation structure. The stator has a cylindrical cavity in the middle, through which the mover passes and there is an air gap. The drive unit, fixed to the middle cylinder block, is connected to the excavator's power battery via an input cable and interacts with the excavator's control system. The nitrogen chamber is located in the upper cylinder body, with an opening at the bottom. The upper end of the mover extends into the nitrogen chamber to compress the nitrogen inside. The chisel is located at the bottom of the lower cylinder and is connected to the lower cylinder via a chisel sleeve and a limiting pin. The chisel sleeve is fixed to the lower cylinder and has an axial range of motion. The lower end of the mover can strike the chisel.

2. The pure electric linear electromagnetic drive breaker according to claim 1, characterized in that, The stator is composed of multiple stacked annular iron cores, with annular grooves cut between the iron cores for placing hollow disc coils. The outer side of the iron cores is provided with lead-out grooves, and the coil leads are led out and connected to each other to form a three-phase winding.

3. The pure electric linear electromagnetic drive breaker according to claim 1, characterized in that, The excitation structure is cylindrical and fits onto the moving shaft. The moving shaft has a shoulder, which, together with the moving shaft sleeve, axially fixes the excitation structure.

4. The pure electric linear electromagnetic drive breaker according to claim 1, characterized in that, The excitation structure is composed of annular permanent magnets and annular magnetic steels stacked axially in an alternating manner, with adjacent permanent magnets having opposite magnetization directions. This structure forms a surface magnetic field that changes periodically along the axis. Buffer blocks are provided on the contact surfaces on both sides of the excitation structure to protect the permanent magnets, which are brittle materials.

5. A pure electric linear electromagnetic drive breaker according to claim 1, characterized in that, The middle cylinder body includes a stator housing and stator end caps. The stator of the linear electromagnetic drive device is located inside the stator housing and fixed by two stator end caps. The middle cylinder body is equipped with a displacement sensor and a temperature sensor to detect the position and speed information of the mover and the internal temperature of the electromagnetic drive device. Each of the two stator end caps is connected to a positioning ring. Both ends of the mover pass through the entire middle cylinder body and extend out of the positioning rings. The inner side of the positioning rings is equipped with bushings and retaining rings, which slide in contact with the shaft surfaces at both ends of the mover.

6. A pure electric linear electromagnetic drive breaker according to claim 5, characterized in that, The two stator end caps of the middle cylinder are each provided with a heat dissipation channel. One end of the heat dissipation channel is connected to the outside through a filter, and the other end is connected to the air gap between the stator and the mover. The external cooling medium enters the air gap through one heat dissipation channel, flows through the inner surface of the stator and is discharged from the other heat dissipation channel, thereby achieving heat dissipation of the linear electromagnetic drive structure.

7. A pure electric linear electromagnetic drive breaker according to claim 2, characterized in that, The driver has a pressure signal interface on its outside that connects to a pressure sensor to receive pressure signals. Inside the driver, a three-phase inverter circuit is installed to convert the DC input of the power battery into a three-phase AC output. The three-phase winding coils inside the stator generate a traveling wave magnetic field that moves in a linear direction under the input of the three-phase AC power. The traveling wave magnetic field interacts with the magnetic field of the mover excitation structure to generate an axial electromagnetic thrust, which drives the mover to perform axial reciprocating motion.

8. A control method for a pure electric linear electromagnetic drive hydraulic breaker according to any one of claims 1-7, characterized in that, The method includes the following steps: Step S1: The hydraulic breaker is in its initial state. The chisel and the mover are pressed down to the lower limit of the stroke by gravity and the initial thrust of the nitrogen chamber, and the chisel and the mover remain in contact. Step S2: The hydraulic breaker enters the ready-to-start state. The excavator controls the hydraulic breaker to descend vertically to hold the target material to be broken. The chisel is lifted by force, and the mover moves upward together. Based on the displacement detected by the position sensor, the driver confirms that the hydraulic breaker has entered the ready-to-start state. In step S3, the hydraulic breaker performs a return lift, the driver outputs three-phase AC power, and the mover is lifted continuously by the electromagnetic thrust, detaching from the chisel and rising a set distance. During this period, the electromagnetic thrust does work against gravity and the thrust of the nitrogen chamber, which is converted into the kinetic energy of the mover, gravitational potential energy and the elastic potential energy of the gas inside the nitrogen chamber. Step S4: When the driver output current reverses, the electromagnetic thrust begins to brake downwards, and it is accelerated downwards. It continues to move upwards until the kinetic energy of the mover returns to zero, and then begins to move downwards. In step S5, the hydraulic breaker enters its stroke. The mover continues to descend and accelerate under the action of electromagnetic thrust, gravity, and nitrogen chamber thrust, reaching its maximum speed when it contacts the chisel at the top dead center. In step S6, the hydraulic breaker impacts the chisel, causing its speed to quickly return to zero. The kinetic energy is converted into impact energy and transmitted to the target material through the chisel. If the target material is not broken, the hydraulic breaker returns to step S2 and continues to operate. If the target material is broken, the driver stops supplying power until the two materials meet and lift again, entering the next impact cycle.

9. The control method for a pure electric linear electromagnetic drive hydraulic breaker according to claim 8, characterized in that, Different impact forces and impact frequencies can be achieved by changing the magnitude of the electromagnetic thrust, the return lifting distance, or adjusting the control strategy. The greater the return lifting distance, the greater the impact force of the hydraulic breaker, but the lower the impact frequency. The output current and power of the linear electromagnetic drive device can be increased or decreased according to the load conditions.

10. The control method for a pure electric linear electromagnetic drive hydraulic breaker according to claim 8, characterized in that, In step S3, for applications requiring greater impact power, the braking detection signal is changed from the mover displacement distance to the mover speed. After the speed is detected to be zero, the driver is commanded to reverse the current and directly enter the stroke stage of step S5, enabling the hydraulic breaker to achieve maximum impact power and impact efficiency.

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