Variable motor, hydraulic system, working machine and motor control method

Abstract

The application discloses a variable motor, a hydraulic system, a construction machine and a motor control method, the variable motor is integrated with a variable electromagnetic valve and a servo oil cylinder, a pipeline is connected between M and G ports of the motor, and a pipeline on-off control mechanism is arranged on the pipeline; the pipeline on-off control mechanism adopts a normally open electromagnetic valve, and the electromagnetic valve is closed after being powered; in the telescopic arm telescopic working condition, the variable electromagnetic valve is powered, and the motor is in minimum displacement; meanwhile, the electromagnetic valve is powered off, the pressure of the A port or the B port of the motor reaches the M port through the G port, and also acts on the rodless cavity of the servo oil cylinder of the motor; if the variable electromagnetic valve is powered off, the pressure of the A port or the B port of the motor can still reach the M port through the G port, and acts on the rodless cavity of the servo oil cylinder of the motor, so that the motor is always in minimum displacement. The application can improve the safety of the super-lift variable motor, significantly reduce the operation risk of the crane, and reduce the risk of arm damage caused by circuit failure.

Description

Technical Field

[0001] This invention belongs to the field of engineering machinery technology, specifically relating to a variable displacement motor, a hydraulic system, engineering machinery, and a motor control method. Background Technology

[0002] Ultra-large tonnage cranes are generally equipped with super-lift devices on their booms to reduce boom deformation and improve lifting performance.

[0003] The winch of the super-lift device is connected to the boom head via a super-lift wire rope (hereinafter referred to as the wire rope). During boom extension, to prevent the wire rope from becoming tangled, the starter of the super-lift motor must maintain a certain pressure to ensure the wire rope has sufficient tension. This tension must be within a reasonable range. If the tension is too low, the wire rope's own weight will cause it to slip out, making it impossible to coil tightly during retraction, resulting in tangling and potential damage under stress. If the boom extension speed is too fast and the winch cannot keep up, the wire rope tension will be too high, causing the boom to tilt upwards and potentially damaging it.

[0004] Similarly, if the winch speed is too slow when the boom retracts, the wire rope will not tighten properly, potentially damaging it later. If the winch speed is too fast, the boom will tilt upwards, possibly causing it to break. After the boom has extended or retracted to its designated position, the motor torque is needed to tighten the wire rope to the specified tension. Under the same pressure, the motor torque is directly proportional to the motor's displacement; to ensure the specified tension is reached, the motor must have a certain displacement.

[0005] For lifting operations, there are currently two main types of lifting motors used in the industry: fixed displacement motors and variable displacement motors.

[0006] Fixed displacement motors are primarily used in models where the required motor displacement variation is minimal—that is, models where the difference between the boom extension / retraction speed and the winch speed is small, and the superlift motor torque is sufficient for superlift tensioning conditions. Generally, all superlifting operations are met by matching the boom extension / retraction speed and the winch speed. When extending the boom, to improve efficiency, the motor displacement is often reduced to allow the winch to achieve a higher speed, thus maximizing the speed of the extension cylinder and minimizing the extension / retraction time. Conversely, when the winch needs to tighten, a larger motor displacement is required to generate greater force and meet the demand for rapid tightening. Therefore, using a fixed displacement motor necessitates balancing these two operating conditions, often sacrificing performance in one condition or partially sacrificing performance in both to achieve a balance, inevitably preventing the attainment of optimal performance in both areas.

[0007] As mentioned earlier, during boom extension and retraction, the wire rope must be extended or retracted synchronously, requiring a high winch speed. After the boom is fully extended or retracted, the wire rope needs to be tightened to increase the rigidity of the boom, requiring the winch to provide a large torque. This presents a technical contradiction: both a large torque and a high speed are required from the motor. Furthermore, as the boom length increases, the contradiction between the extension speed and the tension becomes increasingly significant, making it increasingly difficult for a fixed-displacement motor to meet the demands. Therefore, a variable-displacement motor is upgraded by adding a variable displacement mechanism to the fixed-displacement motor. The variable-displacement motor operates at a small displacement during boom extension and retraction to achieve a high winch speed while maintaining a low wire rope tension. Conversely, when the wire rope needs tightening, the motor operates at a large displacement to obtain a large winch torque, ensuring sufficient tension in the wire rope to meet the tightening requirements.

[0008] Figure 1 The image shows a variable displacement motor solution currently used in the industry, and its working principle is as follows:

[0009] The pressure from port A or port B of motor 1 acts on the rod chamber of servo cylinder 3, pushing servo cylinder 3 to move to the right, bringing motor 1 to its maximum displacement. If the variable displacement solenoid valve 2 of motor 1 is energized, the pressure from port A or port B of motor 1 simultaneously enters the rodless chamber of servo cylinder 3 through the variable displacement solenoid valve 2. According to the differential cylinder principle, servo cylinder 3 moves to the left, bringing motor 1 to its minimum displacement. During boom extension / retraction, variable displacement solenoid valve 2 is energized, and motor 1 is at its minimum displacement; during hoist tensioning, variable displacement solenoid valve 2 is de-energized, and motor 1 is at its maximum displacement.

[0010] The existing technical problems with variable displacement motors are:

[0011] Existing variable displacement motors are all electro-proportional variable displacement motors, which pose safety hazards. Specifically, motor 1 initially operates at its maximum displacement for winch tensioning. After the variable displacement solenoid valve 2 is energized, motor 1 swings to a small displacement, at which point the speed is relatively high and the wire rope tension is low, used for boom extension. If a circuit fault occurs (e.g., poor wiring contact or open circuit during boom extension), causing the variable displacement solenoid valve 2 to lose power, motor 1 will automatically swing back to its maximum displacement. This increases the torque of motor 1 and the wire rope tension, exceeding the allowable range for wire rope tension during boom extension, causing the boom to bend or break. Summary of the Invention

[0012] Objectives of the Invention: The first objective of this invention is to provide a variable displacement motor to address the risk of boom damage caused by power failure of the variable displacement solenoid valve due to circuit malfunction; the second objective of this invention is to provide a control method for the variable displacement motor; the third objective of this invention is to provide a hydraulic system incorporating the variable displacement motor; and the fourth objective of this invention is to provide engineering machinery incorporating the hydraulic system.

[0013] Technical solution: The variable displacement motor of the present invention integrates a variable displacement solenoid valve and a servo cylinder. A pipeline is connected to the M port and G port of the motor. A pipeline on / off control mechanism is provided on the pipeline to ensure that the motor can still maintain the minimum displacement when the variable displacement solenoid valve is de-energized.

[0014] Furthermore, the pipeline on / off control mechanism adopts a normally open solenoid valve, which is electromagnetically closed when energized.

[0015] Furthermore, the solenoid valve can be a two-position two-way solenoid valve, a two-position three-way solenoid valve, or a two-position four-way solenoid valve.

[0016] Furthermore, the pipeline on / off control mechanism adopts a manual valve.

[0017] Furthermore, the pipeline on / off control mechanism employs a hydraulic valve.

[0018] The variable displacement motor control method described in this invention, during the boom extension and retraction operation, energizes the variable displacement solenoid valve, and the motor is at its minimum displacement. Simultaneously, when the solenoid valve is de-energized, the pressure at port A or B of the motor reaches port M through port G, and also acts on the rodless chamber of the motor's servo cylinder. At this time, even if the variable displacement solenoid valve is de-energized, the pressure at port A or B of the motor can still reach port M through port G, acting on the rodless chamber of the motor's servo cylinder, always keeping the motor at its minimum displacement.

[0019] Furthermore, during hoisting tensioning, if the variable solenoid valve is de-energized, the pressure at port A or B of the motor acts on the rod chamber of the motor's servo cylinder; if the solenoid valve is energized, the oil circuit between port G and port M is cut off, and the pressure at port A or B of the motor cannot act on the rodless chamber of the motor's servo cylinder, causing the servo cylinder to move to the right, and the motor to be at maximum displacement; if the solenoid valve malfunctions and loses power at this time, then port G and port M communicate, and pressurized oil enters the rodless chamber of the motor's servo cylinder, and the motor will switch to low displacement.

[0020] The hydraulic system of the present invention includes the variable displacement motor.

[0021] The engineering machinery described in this invention includes the hydraulic system.

[0022] Furthermore, the engineering machinery mentioned includes cranes.

[0023] The hydraulic system and engineering machinery described above have the advantages of variable displacement motors.

[0024] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0025] This invention can improve the safety of variable displacement motors, significantly reduce the operational risks of cranes, and reduce the risk of boom damage due to circuit failures. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of an existing variable displacement motor;

[0027] Figure 2 This is a schematic diagram of the structure of the variable motor provided in the embodiment of this application. Detailed Implementation

[0028] The invention will now be further described with reference to the accompanying drawings.

[0029] Appendix Figure 1 and 2 The accompanying figure labels are as follows:

[0030] 1. Motor; 2. Variable solenoid valve; 3. Servo cylinder; 4. Pipeline on / off control mechanism.

[0031] This application provides a variable displacement motor, such as... Figure 2 As shown, the motor 1 integrates a variable solenoid valve 2 and a servo cylinder 3. A pipeline is connected to the M port and G port of the motor 1. A pipeline on / off control mechanism 4 is installed on the pipeline to ensure that the motor 1 can maintain the minimum displacement even after the variable solenoid valve 2 is de-energized.

[0032] In this embodiment, the pipeline on / off control mechanism 4 adopts a normally open solenoid valve, which closes electromagnetically upon energization. More specifically, the solenoid valve is a two-position, two-way solenoid valve.

[0033] This application embodiment also provides a control method for the variable motor, including:

[0034] During the boom extension / retraction operation, variable solenoid valve 2 is energized, and motor 1 is at its minimum displacement. Simultaneously, when the solenoid valve is de-energized, the pressure at port A or B of motor 1 travels through port G to port M, also acting on the rodless chamber of the servo cylinder 3 of motor 1. Even if variable solenoid valve 2 is de-energized, the pressure at port A or B of motor 1 can still travel through port G to port M, acting on the rodless chamber of the servo cylinder 3 of motor 1, thus always keeping motor 1 at its minimum displacement. This prevents an increase in the torque of motor 1 and avoids damage to the boom.

[0035] During hoisting tensioning, if the variable solenoid valve 2 is de-energized, the pressure from port A or B of motor 1 acts on the rod chamber of the servo cylinder 3 of motor 1. If the solenoid valve is energized, the oil circuit between ports G and M is cut off, and the pressure from ports A or B of motor 1 cannot act on the rodless chamber of the servo cylinder 3 of motor 1. Therefore, the servo cylinder 3 of motor 1 moves to the right, and motor 1 is at its maximum displacement. If the solenoid valve malfunctions and loses power at this time, ports G and M communicate, and pressurized oil enters the rodless chamber of the servo cylinder 3 of motor 1, causing motor 1 to operate at a lower displacement. This will reduce the motor torque and prevent tensioning, but it will not damage the equipment; only troubleshooting and repair are required.

[0036] It should be noted that the solenoid valves controlling the on / off state of ports M and G of motor 1 are not limited to two-position two-way solenoid valves; for example, they can also be two-position three-way or two-position four-way solenoid valves. Similarly, the pipeline on / off control mechanism 4 is not limited to solenoid valves; for example, manual valves or hydraulic valves can be used to control the on / off state of ports G and M of the motor. The control method is similar to that of solenoid valves and will not be elaborated upon here. In other words, any scheme that controls the on / off state of ports G and M of the motor through a pipeline on / off control mechanism to achieve the target displacement of the motor should be considered within the scope of protection of this invention.

[0037] This application also provides a hydraulic system, including the variable displacement motor described in this application embodiment.

[0038] This application also provides an engineering machinery, including the hydraulic system described in this application embodiment. The engineering machinery may be, for example, a crane, and the variable displacement motor is applied to the crane's super-lift device. Of course, the engineering machinery is not limited to cranes, but also includes other engineering machinery that uses variable displacement motor control to improve equipment safety.

Claims

1. A control method for a variable displacement motor, characterized in that, The variable displacement motor integrates a variable displacement solenoid valve and a servo cylinder. A pipeline connects the motor's M and G ports, and a pipeline on / off control mechanism is installed on this pipeline to maintain the minimum displacement even after the variable displacement solenoid valve is de-energized. The pipeline on / off control mechanism uses a normally open solenoid valve, which closes electromagnetically upon energization. The control method includes: During the boom extension / retraction operation, the variable solenoid valve is energized, and the motor is at its minimum displacement. At the same time, when the solenoid valve is de-energized, the pressure at port A or B of the motor reaches port M through port G, and also acts on the rodless chamber of the motor's servo cylinder. At this time, if the variable solenoid valve is de-energized, the pressure at port A or B of the motor can still reach port M through port G, and act on the rodless chamber of the motor's servo cylinder, always keeping the motor at its minimum displacement. When the hoist is in tensioning mode, if the variable solenoid valve is de-energized, the pressure at port A or B of the motor acts on the rod chamber of the motor's servo cylinder. If the solenoid valve is energized, the oil circuit between ports G and M is cut off, and the pressure at ports A or B of the motor cannot act on the rodless chamber of the motor's servo cylinder. The servo cylinder moves to the right, and the motor is at its maximum displacement. If the solenoid valve malfunctions and loses power at this time, ports G and M communicate, and pressurized oil enters the rodless chamber of the motor's servo cylinder, causing the motor to switch to a smaller displacement.

2. The control method for a variable displacement motor according to claim 1, characterized in that, The solenoid valves can be two-position two-way solenoid valves, two-position three-way solenoid valves, or two-position four-way solenoid valves.

3. The control method for a variable displacement motor according to claim 1, characterized in that, The pipeline on / off control mechanism uses a manual valve.

4. The control method for a variable displacement motor according to claim 1, characterized in that, The pipeline on / off control mechanism uses hydraulic valves.

5. A hydraulic system, characterized in that, The control method of the variable motor according to any one of claims 1 to 4.

6. An engineering machinery, characterized in that, Includes the hydraulic system described in claim 5.

7. The engineering machinery according to claim 6, characterized in that, The engineering machinery mentioned includes cranes.

Images