Variable-speed electric cylinder

Abstract

The invention discloses a variable-speed electric cylinder which comprises a cylinder body unit and a driving unit. The driving unit comprises a motor I, a motor II and a speed change mechanism, the motor I and the motor II are both in transmission connection with the speed change mechanism, and an output shaft of the speed change mechanism is in transmission connection with a lead screw of the cylinder body unit. The multi-degree-of-freedom parallel mechanism can operate at different movement speeds, and meets the requirements of different working conditions for output force and movement speeds to a certain extent.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric cylinders, and in particular relates to a variable speed electric cylinder. Background Art

[0002] As a high-precision linear actuator, the electric cylinder is designed for medium to high load continuous motion conditions. Its core advantage lies in its long life and support for high-frequency cyclic use.

[0003] In actual use, electric cylinders often need to face changing working conditions. Electric cylinders must provide the required thrust force and thrust speed according to actual needs.

[0004] In some working conditions, the required jacking force is large, but the required jacking speed is small;

[0005] On the contrary, in some working conditions, the required jacking force is very small, but the required jacking speed is very high;

[0006] Due to the changing working conditions, the motor of the electric cylinder usually requires a large power to cover the needs of different working conditions. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a variable speed electric cylinder that can operate at different movement speeds in response to the deficiencies in the above-mentioned existing technology, and to a certain extent adapt to the requirements of different working conditions for output force and movement speed, thereby reducing the required power of the motor.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: a variable speed electric cylinder, comprising: a cylinder unit and a drive unit; the drive unit comprises motor I, motor II and a speed change mechanism;

[0009] The speed change mechanism includes a sun gear, planetary gears, a planetary carrier, a ring gear and a driving gear;

[0010] The sun gear is connected to the output shaft of motor I;

[0011] The planetary gears are mounted on a planetary carrier, and the planetary gears are meshed with the sun gear;

[0012] The gear ring is coaxially sleeved on the outside of the sun gear, and the inner teeth of the gear ring are meshed with the planetary gears;

[0013] The outer teeth of the gear ring are meshed with the driving gear;

[0014] The driving gear is connected to the output shaft of motor II;

[0015] The output shaft of the planetary carrier is connected to the screw drive of the cylinder unit.

[0016] The above-mentioned variable speed electric cylinder also includes a first box body, and the speed change mechanism is installed in the first box body.

[0017] In the above-mentioned variable speed electric cylinder, the output shaft of the planetary carrier and the lead screw of the cylinder unit are connected through a gear pair.

[0018] The above-mentioned variable speed electric cylinder, the gear pair is installed in the second box body.

[0019] In the above-mentioned variable speed electric cylinder, the motor I and the motor II are both servo motors with brakes.

[0020] The variable speed electric cylinder further comprises a multi-turn absolute value encoder, which is drivingly connected to the output shaft of the planetary carrier.

[0021] The variable speed electric cylinder has a plurality of planetary gears, and the plurality of planetary gears are evenly distributed on the planetary carrier along the circumferential direction of the sun gear.

[0022] A second aspect of the present invention discloses a method for controlling the variable speed electric cylinder, comprising the following steps:

[0023] (a) Establish the speed ratio of motor I as i1, the speed ratio of motor II as i2, and set the current threshold as A_set;

[0024] (b) During the initial operation phase, motor II is controlled to operate independently, and the operating current A2 of motor II is monitored in real time. (c) When A2 > A_set is detected, a stop signal is triggered to brake motor II, while motor I is activated to start operating.

[0025] (d) Continuously monitor the operating current A1 of motor I during its operation;

[0026] (e) When A1 < A_set, a switching command is generated to stop motor I and restart motor II;

[0027] (f) By alternately executing the closed-loop control of steps (c) to (e), adaptive matching of the load range and speed range of the electric cylinder is achieved.

[0028] A third aspect of the present invention discloses a method for controlling a variable speed electric cylinder, comprising the following steps:

[0029] S1. Establish the input torque of motor I as M1 and the input torque of motor II as M2;

[0030] When the sun gear and the ring gear rotate in the same direction, the torque at the screw end is [M1×i1-M2×i2]×η;

[0031] i1 is the speed ratio of motor I, i2 is the speed ratio of motor II, and η is the transmission efficiency;

[0032] The speed of the screw end is

[0033] When the sun gear and the ring gear rotate in opposite directions, the torque at the screw end is [M1×i1+M2×i2]×η;

[0034] The speed of the screw end is

[0035] S2. Real-time monitoring of the required parameters of the jacking load and the jacking speed;

[0036] S3. According to the monitoring results, the direction of motor I or motor II is adjusted to achieve switching control between high torque mode and high speed mode.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] 1. The drive unit uses two motors, one for use and one for backup, which plays a redundancy role. When one of the motors fails, its motor brakes and transmits the nut position signal of the cylinder unit to the other motor, which continues to drive the electric cylinder to move. It is particularly suitable for important working occasions where the electric cylinder cannot be stopped at will.

[0039] 2. The drive unit uses two motors, which is suitable for occasions with a wide range of loads and speeds. Some working conditions require that the speed can be very slow when heavy loads are applied, while the speed can be very high when light loads are applied. At this time, the different speed ratios of the two transmission lines can be fully utilized. For example, when motor II brakes, motor I uses a small speed ratio to make the electric cylinder extend and retract at high speed, while when motor I brakes, motor II uses a large speed ratio to make the electric cylinder extend and retract at low speed, thereby allowing the electric cylinder to transmit a large load.

[0040] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a structural schematic diagram of the present invention.

[0042] Figure 2 for Figure 1 A sectional view of a vertical section.

[0043] Figure 3 for Figure 2 A partial enlarged view of .

[0044] Figure 4 It is a cross-sectional view of a horizontal section of the present invention.

[0045] Description of the accompanying drawings:

[0046] 1—Cylinder unit; 2—Drive unit; 3—Screw;

[0047] 4—sun gear; 5—planet gear; 6—planet carrier;

[0048] 7—ring gear; 8—drive gear; 9—first housing;

[0049] 10—Gear pair; 11—Multi-turn absolute encoder. DETAILED DESCRIPTION

[0050] like Figure 1 — Figure 4 As shown, Figure 1 As shown, a variable speed electric cylinder includes: a cylinder unit 1 and a drive unit 2; the drive unit 2 includes a motor I, a motor II and a speed change mechanism, the motor I and the motor II are both transmission-connected to the speed change mechanism, and the output shaft of the speed change mechanism is transmission-connected to the screw 3 of the cylinder unit 1.

[0051] In this embodiment, the speed change mechanism includes a sun gear 4, planetary gears 5, a planetary carrier 6, a ring gear 7 and a drive gear 8; the sun gear 4 is connected to the output shaft of motor I; the planetary gears 5 are mounted on the planetary carrier 6, and the planetary gears 5 and the sun gear 4 are meshed; the ring gear 7 is coaxially sleeved on the outside of the sun gear 4, and the inner teeth of the ring gear 7 are meshed with the planetary gears 5; the outer teeth of the ring gear 7 are meshed with the drive gear 8; the drive gear 8 is connected to the output shaft of motor II; the output shaft of the planetary carrier 6 is transmission-connected to the screw 3 of the cylinder unit 1.

[0052] In this embodiment, a first housing 9 is further included, and the speed change mechanism is installed in the first housing 9 .

[0053] In this embodiment, the output shaft of the planetary carrier 6 and the lead screw 3 of the cylinder unit 1 are connected through a gear pair 10 .

[0054] In this embodiment, the gear pair 10 is installed in the second housing.

[0055] In this embodiment, both the motor I and the motor II are servo motors with brakes.

[0056] In this embodiment, a multi-turn absolute value encoder 11 is further included, and the multi-turn absolute value encoder 11 is drivingly connected to the output shaft of the planet carrier 6 .

[0057] In this embodiment, there are multiple planetary gears 5 , and the multiple planetary gears 5 are evenly distributed on the planet carrier 6 along the circumferential direction of the sun gear 4 .

[0058] When the present invention is used, when the servo motor II is in the braking state, the motor I transmits the torque to the sun gear 4, the sun gear 4 transmits the torque to the planetary gear 5, drives the planetary carrier 6 to rotate, and transmits the torque to the lead screw 3 through the gear pair 10, thereby driving the push rod to do reciprocating linear motion. At this time, the speed ratio of the electric cylinder is

[0059] When servo motor I is in a specified state, servo motor II transmits torque to the driving wheel, which meshes with the outer teeth of the ring gear 7, driving the ring gear 7 to rotate. The ring gear 7 transmits torque to the planetary carrier 6 to rotate, and transmits torque to the lead screw 3 through the gear pair 10, thereby driving the push rod to do reciprocating linear motion. At this time, the speed ratio of the electric cylinder is

[0060] When Motor I stops, the Motor I driver transmits the position signal to the Motor II driver to ensure that the position of the electric cylinder is not messed up when the drive of Motor I switches to that of Motor II, and vice versa. Motor I and Motor II do not drive the electric cylinder at the same time to ensure the correct position.

[0061] Those skilled in the art should know that the planetary gear pair 10 connected to the motor I can be a multi-stage transmission, and the fixed-axis gear pair 10 connected to the motor II can also be a multi-stage transmission.

[0062] Practical Application Example 1: The electric cylinder's two motors, one active and one standby, provide redundancy. If one motor fails, it engages the brake, transmitting the position signal to the other motor, which then continues to drive the cylinder. This is particularly suitable for critical work environments where the cylinder cannot be shut down at will. Motor I is driven by low-voltage AC 220 / 380V or DC 600V, while Motor II is controlled by a safe 24V voltage. During normal operation, Motor I operates, while Motor II is driven by the backup power supply. If the main power supply fails for some reason, the backup power supply takes over. This is particularly useful for vehicle steering applications, where the backup power supply can continue to drive Motor II after a power outage.

[0063] Practical Application Case 2: Suitable for applications with a wide range of loads and speeds. Some operating conditions require very slow speeds for heavy loads, while very high speeds for light loads. In these cases, the different speed ratios of the two transmission lines can be fully utilized. For example, when Motor II brakes, Motor I uses a small speed ratio to enable the electric cylinder to extend and retract at high speed. When Motor I brakes, Motor II uses a large speed ratio to enable the electric cylinder to extend and retract at low speed, thereby enabling the electric cylinder to transmit large loads at high speeds. If a single motor were used, the motor power would be very high, often far greater than the combined power of the two motors described in this patent. For example, in the oil industry, when the top drive is unloaded or lightly loaded, the electric cylinder needs to extend and retract at high speed. However, when the electric cylinder is running with a large number of drill rods installed or when the drill rod is stuck, the electric cylinder needs to be able to handle a large load at a lower speed.

[0064] Practical Application Example 3: When both servo motors I and II are in motion, the electric cylinder's position is fed back by a multi-turn absolute encoder 11, enabling infinitely variable speeds. If servo motor I is the main output motor, a high-power motor is selected, and servo motor II is the speed-regulating motor, with a low-power motor selected for motor II, infinitely variable speed control can be achieved using low power to control high power. This invention allows for a very wide operating range of speeds and loads, which is unattainable with conventional electric cylinders.

[0065] When the present invention is used, motor I and motor II can be controlled according to information of the multi-turn absolute value encoder.

[0066] Motor I can realize multiple speed changes or multiple load changes under the condition of constant power, and has the function of constant power "universal use".

[0067] When the rotation direction of the sun gear 4 is consistent with that of the ring gear 7, the speed of the screw 3 is

[0068]

[0069] When the sun gear 4 rotates in the opposite direction to the ring gear 7, the speed of the screw 3 is

[0070]

[0071] Compared with the traditional single motor structure, the present invention has great advantages in energy saving, such as:

[0072] The required working condition of an electric cylinder is:

[0073] Heavy-load working conditions: thrust requirement is 5500KN, speed requirement is 0-100mm / s;

[0074] Light load condition: thrust requirement is 1000KN, speed requirement is 0-600mm / s;

[0075] Assuming the transmission efficiency is 0.75, the single motor of the traditional electric cylinder needs

[0076] However, the present invention only requires 733KW+800KW=1533KW, and 1533KW is much smaller than 4400KW. In actual applications, the power of the control components used in conjunction with the 1533KW motor will also be much smaller than the power of the control components used in conjunction with the 4400KW motor. Specifically, motor I (733KW) corresponds to heavy-load conditions, and motor II (800KW) corresponds to light-load conditions.

[0077] In practical applications, the no-load energy consumption of motor I (733KW) and motor II (800KW) of the present invention is also less than that of a 4400KW motor. Compared with traditional electric cylinders, the energy consumption of the motors of the present invention and the cost of the motors and supporting control components are significantly reduced.

[0078] A second aspect of the present invention discloses a method for controlling the variable speed electric cylinder, comprising the following steps:

[0079] (a) Establish the speed ratio of motor I as i1, the speed ratio of motor II as i2, and set the current threshold as A_set;

[0080] (b) During the initial operation phase, motor II is controlled to operate independently, and the operating current A2 of motor II is monitored in real time. (c) When A2 > A_set is detected, a stop signal is triggered to brake motor II, while motor I is activated to start operating.

[0081] (d) Continuously monitor the operating current A1 of motor I during its operation;

[0082] (e) When A1 < A_set, a switching command is generated to stop motor I and restart motor II;

[0083] (f) By alternately executing the closed-loop control of steps (c) to (e), adaptive matching of the load range and speed range of the electric cylinder is achieved.

[0084] A third aspect of the present invention discloses a method for controlling a variable speed electric cylinder, comprising the following steps:

[0085] S1. Establish the input torque of motor I as M1 and the input torque of motor II as M2;

[0086] When the sun gear and the ring gear rotate in the same direction, the torque at the screw end is [M1×i1-M2×i2]×η;

[0087] i1 is the speed ratio of motor I, i2 is the speed ratio of motor II, η is the transmission efficiency, η is 0.85;

[0088] The speed of the screw end is

[0089] When the sun gear and the ring gear rotate in opposite directions, the torque at the screw end is [M1×i1+M2×i2]×η;

[0090] The speed of the screw end is

[0091] S2. Real-time monitoring of the required parameters of the jacking load and the jacking speed;

[0092] S3. According to the monitoring results, the direction of motor I or motor II is adjusted to achieve switching control between high torque mode and high speed mode.

[0093] In summary, the present invention has four working modes:

[0094] Mode 1: Motor II is working and Motor I is stopped;

[0095] Mode 2: Motor I works and Motor II stops;

[0096] Mode 3: Both motors I and II are working, driving the sun gear and ring gear to rotate in the same direction;

[0097] Mode 3: Both motor I and motor II are working, driving the sun gear and ring gear to rotate in opposite directions.

[0098] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A variable speed electric cylinder comprising: Cylinder unit and drive unit; characterized in that the drive unit includes motor I, motor II and a speed change mechanism; The speed change mechanism includes a sun gear, planetary gears, a planetary carrier, a ring gear and a driving gear; The sun gear is connected to the output shaft of motor I; The planetary gears are mounted on the planetary carrier, and the planetary gears are meshed with the sun gear; The gear ring is coaxially sleeved on the outside of the sun gear, and the inner teeth of the gear ring are meshed with the planetary gears; The outer teeth of the gear ring are meshed with the driving gear; The driving gear is connected to the output shaft of motor II; The output shaft of the planetary carrier is connected to the screw drive of the cylinder unit.

2. The variable speed electric cylinder according to claim 1, characterized in that: It also includes a first case, in which the speed change mechanism is installed.

3. The variable speed electric cylinder according to claim 1 or 2, characterized in that: The output shaft of the planetary carrier and the lead screw of the cylinder unit are connected through a gear pair.

4. The variable speed electric cylinder according to claim 3, characterized in that: The gear pair is installed in the second housing.

5. The variable speed electric cylinder according to claim 1, characterized in that: There are multiple planetary gears, and the multiple planetary gears are evenly distributed on the planetary carrier along the circumferential direction of the sun gear.

6. The variable speed electric cylinder according to claim 1, characterized in that: Both the motor I and the motor II are servo motors with brakes.

7. The variable speed electric cylinder according to claim 6, characterized in that: It also includes a multi-turn absolute value encoder, which is drivingly connected to the output shaft of the planetary carrier.

8. The control method of the variable speed electric cylinder according to any one of claims 1 to 7, characterized in that: The following steps are involved: (a) Establish the speed ratio of motor I as i1, the speed ratio of motor II as i2, and set the current threshold as A_set; (b) During the initial operation phase, motor II is controlled to operate independently, and the operating current A2 of motor II is monitored in real time. (c) When A2 > A_set is detected, a stop signal is triggered to brake motor II, while motor I is activated to start operating. (d) Continuously monitor the operating current A1 of motor I during its operation; (e) When A1 < A_set, a switching command is generated to stop motor I and restart motor II; (f) By alternately executing the closed-loop control of steps (c) to (e), adaptive matching of the load range and speed range of the electric cylinder is achieved.

9. The control method of the variable speed electric cylinder according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Establish the input torque of motor I as M1 and the input torque of motor II as M2; When the sun gear and the ring gear rotate in the same direction, the torque at the screw end is [M1×i1-M2×i2]×η; i1 is the speed ratio of motor I, i2 is the speed ratio of motor II, and η is the transmission efficiency; The speed of the screw end is When the sun gear and the ring gear rotate in opposite directions, the torque at the screw end is [M1×i1+M2×i2]×η; The speed of the screw end is S2. Real-time monitoring of the required parameters of the jacking load and the jacking speed; S3. According to the monitoring results, the direction of motor I or motor II is adjusted to achieve switching control between high torque mode and high speed mode.

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