CN118346727A - Electric mechanical braking electric cylinder and braking method thereof - Google Patents

Abstract

The invention discloses an electric mechanical braking electric cylinder and a braking method thereof. The electric cylinder comprises a screw rod, wherein a rotor shaft is rotatably sleeved on the screw rod, a rotor is sleeved on the periphery of the rotor shaft, and a stator is sleeved on the periphery of the rotor; the axial front end part of the rotor shaft is provided with a primary sun gear, the primary sun gear is connected with an output shaft through a hollow planetary reducer in a transmission way, an internal thread matched with a screw rod is arranged inside the output shaft, and the output shaft is sleeved on the screw rod in a transmission way and is connected with the screw rod; and a pressure sensor is arranged in the hollow planetary reducer or at the front end of the screw rod. The method comprises the following steps: the motor is powered on, the rotor rotates, and the rotor drives a rotor output shaft in transmission connection with the rotor to rotate together; the rotary motion of the rotor shaft is transmitted to a first-stage sun gear, and the rotary motion is transmitted to an output shaft through a hollow planetary reducer; the output shaft rotates, and the screw rod is driven to push out outwards by taking the internal thread structure as a screw rod nut.

Description

Electric mechanical braking electric cylinder and braking method thereof

Technical Field

The invention relates to the technical field of electric cylinders, in particular to an electric mechanical braking electric cylinder and a braking method thereof.

Background

At present, urban modern railway vehicles are developing towards intellectualization, full electrification and greenization, and the traditional air braking and hydraulic braking cannot meet the new development trend of the vehicles. The electronic mechanical braking unit has the advantages of good control performance, simple system, light weight, low maintenance cost, high energy utilization efficiency and the like, and has the potential of replacing the original air braking and hydraulic braking system of the urban rail vehicle.

With the innovation of industrial control technology and the vigorous development of electronic information technology, an electronic mechanical braking system is generated. The electromechanical braking system uses an electric wire as a medium, transmits a braking instruction through an electric signal, has the advantages of simple pipelines, high energy efficiency, high response speed and the like, and has become the development trend of future railway vehicle braking systems.

In order to realize accurate control and feedback of output force and displacement, an electric cylinder in the current electromechanical brake unit is required to be additionally provided with a rotary transformer, a pressure sensor and the like, so that the structure of the electric cylinder becomes complex, and the volume, the weight and the like have optimized space; because the reduction ratio of the speed reducer is smaller due to space limitation, the output torque of the torque motor is larger, the power is higher, and the power load consumption of the whole vehicle is larger during the common braking; when parking and parking braking, the torque that the power-off brake needs to overcome is great, so that the power requirement is increased when the power-off brake is electrified, the heating is increased, and the performance and the service life of the power-off brake are influenced.

Disclosure of Invention

The invention aims at: aiming at the problems, the electric cylinder for braking the electric machine and the braking method thereof are provided, so that the space is saved, the integration level is higher, and the compactness is realized.

The technical scheme adopted by the invention is as follows:

An electric cylinder for electromechanical braking comprises a screw rod, wherein a rotor shaft is rotatably sleeved on the screw rod, a rotor is sleeved on the periphery of the rotor shaft, and a stator is sleeved on the periphery of the rotor; the axial front end part of the rotor shaft is provided with a primary sun gear, the primary sun gear is connected with an output shaft through a hollow planetary reducer in a transmission way, an internal thread matched with a screw rod is arranged inside the output shaft, and the output shaft is sleeved on the screw rod in a transmission way and is connected with the screw rod; and a pressure sensor is arranged in the planetary reducer or at the front end of the screw rod.

Alternatively, the axial front end of the screw rod is provided with a push head.

Alternatively, the primary sun gear and the rotor shaft are integrally formed.

Alternatively, the periphery of the primary sun gear is provided with a plurality of primary planet gears, and the plurality of primary planet gears are connected through a primary planet carrier; the first-stage planetary gear is in transmission connection with a second-stage sun gear, a plurality of second-stage planetary gears are arranged on the periphery of the second-stage sun gear, and the plurality of second-stage planetary gears are connected through a second-stage planetary carrier; the second-stage planet wheel is connected with the output shaft.

Alternatively, the output shaft is arranged in front of the primary sun gear in the axial direction, and a sealing bearing is arranged between the output shaft and the primary sun gear in the axial direction.

Alternatively, spoke type pressure sensors are arranged in the hollow planetary reducer.

Alternatively, a screw push-pull sensor is arranged at the front end of the screw rod.

Alternatively, the rear end of the rotor shaft is provided with a power-off brake through a brake mounting plate.

Alternatively, the rotor shaft is provided with a rotary transformer.

Optionally, the motor further comprises a motor shell, wherein the screw rod, the rotor, the stator, the primary sun gear, the hollow planetary reducer and the output shaft are arranged in the motor shell, a front cover is arranged on the front side of the motor shell in the axial direction, and the screw rod penetrates out of the front cover forwards; the rear side of the motor main body is provided with a rear cover.

A braking method of an electromechanical brake electric cylinder, comprising the steps of:

Step 1, a motor is powered on, a rotor rotates according to a certain direction and a certain rotating speed, and the rotor drives a rotor output shaft in transmission connection with the rotor to rotate together;

Step 2, the rotary motion of the rotor shaft is transmitted to a first-stage sun gear, and the first-stage sun gear transmits the rotary motion to an output shaft through a hollow planetary reducer to realize speed reduction and moment increase;

And 3, the output shaft rotates, the screw rod is driven to push out outwards through an internal thread structure serving as a screw rod nut to perform linear motion, conversion from the rotation motion to the linear motion and from torque to linear thrust is completed, at the moment, the torque is output by a motor through pressure feedback of a pressure sensor, and the accurate control of braking thrust is realized.

Alternatively, in the step 3, the front end of the screw rod is pushed out and then acts on the brake shoe and the brake wheel forwards, and in the braking process, the reaction force of the brake shoe is transmitted to the output shaft through the screw rod and then transmitted to the spoke type pressure sensor in the hollow planetary reducer, and the braking force is obtained through data acquisition.

Alternatively, in the step 3, the screw rod is pushed out during braking and acts on one end of the screw rod type push-pull sensor, and the other end of the screw rod type push-pull sensor is directly connected with the clamp, the brake shoe and the like to directly measure the push-out force of the screw rod end.

Alternatively, the method further comprises the step 4 of powering off the brake, wherein the magnetic force of the electromagnetic coil disappears, the friction plate is attached to the brake mounting plate under the action of the spring force, and generates friction force for preventing the rotor shaft from rotating, the rotor shaft cannot perform rotational movement, the push-out state of the screw rod during braking is maintained, and the braking force during braking is locked and always maintained.

In summary, due to the adoption of the technical scheme, the beneficial effects of the invention are as follows:

1. the invention provides an electric mechanical braking electric cylinder and a braking method thereof, wherein a hollow torque motor is combined with a second-stage hollow planetary reducer, a torque motor rotor is arranged on a first-stage sun gear of the hollow planetary reducer, the first-stage sun gear transmits rotation torque to a second-stage sun gear through a first-stage planet carrier, and then the second-stage sun gear is connected with a screw rod nut through an output shaft of the hollow planetary reducer, and the screw rod is connected with a push rod head to realize conversion from electric energy to mechanical thrust, namely conversion from rotary motion to linear motion.

2. According to the electric mechanical braking cylinder and the braking method thereof, provided by the invention, the output torque requirement of the torque motor and the parking torque required to be overcome by the parking mechanism can be effectively reduced through the speed reduction and torque increase effects of the hollow planetary reducer; the sensor is directly arranged on the push rod to monitor the output force of the electric cylinder in real time; when the power-off brake at the tail part is electrified, the motor rotor, the nut and the like can rotate freely, and when parking braking is needed, the rotating part can be rapidly clamped after the power-off brake is powered off, so that the parking function after parking is realized.

3. The invention provides an electric cylinder for braking an electric machine and a braking method thereof, which adopt structures such as a motor, a hollow planetary reducer, a screw rod, a force sensor, a power-off brake and the like, wherein a torque motor provides output torque, the screw rod converts rotary motion into linear motion through the reducer or is directly connected to the screw rod, and is connected to a clamp and other devices, so that braking is finally realized, the conversion process from electric energy to braking force is realized, and the electric cylinder has the advantages of quick response, light weight, small volume and no need of air or hydraulic medium compared with braking modes such as air, hydraulic pressure and the like. The hydraulic brake pipeline and the brake fluid are canceled, so that the problems of replacement of hydraulic oil and leakage of the hydraulic oil are solved, and the environment is protected; the air compressor is omitted, vibration sources of the system are reduced, mechanical connection is few, no pneumatic and hydraulic brake pipelines are arranged, and the quality of the whole braking system can be effectively reduced.

4. According to the electric cylinder for braking the electric machine and the braking method thereof, provided by the invention, the mode of combining the motor and the hollow planetary reducer is adopted, the pressure sensor is integrated into the planetary reducer structure, the installation space is reduced, the magnitude of braking force can be accurately controlled through the feedback of the magnitude of real-time force of the pressure sensor, and the braking process is more stable, safer and more comfortable. The abrasion of the brake disc and the brake shoe caused by overlarge braking force is reduced, and the condition of the broken brake shoe holding can be accurately judged through the magnitude of the pressure value of the pressure sensor.

Drawings

The invention will now be described by way of example and with reference to the accompanying drawings in which:

fig. 1 is a schematic structural view of an electromechanical brake electric cylinder.

FIG. 2 is a schematic view of a hollow planetary reducer

Fig. 3 is a schematic view of the electric brake cylinder in a braking state.

The marks in the figure: the brake device comprises the following components of a 1-push head, a 2-screw rod, a 3-output shaft, a 4-front cover, a 5-hollow planetary reducer, a 51-first-stage planetary gear, a 52-first-stage planetary carrier, a 53-spoke type pressure sensor, a 54-second-stage planetary gear, a 55-second-stage sun gear, a 56-second-stage planetary carrier, a 6-sealing bearing, a 7-motor housing, an 8-stator, a 9-rotor, a 10-rotor shaft, an 11-rotor compression ring, a 12-stator compression ring, a 13-rotation transformer, a 14-brake mounting plate, a 15-transition bearing, a 16-anti-falling plate, a 17-rear cover, an 18-power-loss brake, a 19-clamp, a 20-brake pad and a 21-brake disc.

Detailed Description

The present invention will be described in detail with reference to the accompanying drawings.

All of the features disclosed in this specification, or all of the steps in a method or process disclosed, may be combined in any combination, except for mutually exclusive features and/or steps.

Any feature disclosed in this specification may be replaced by alternative features serving the same or equivalent purpose, unless expressly stated otherwise. That is, each feature is one example only of a generic series of equivalent or similar features, unless expressly stated otherwise.

An electric mechanical braking cylinder, as shown in fig. 1-3, comprises a screw rod 2, wherein a rotor shaft 10 is rotatably sleeved on the screw rod 2, a rotor 9 is sleeved on the periphery of the rotor shaft 10, and a stator 8 is sleeved on the periphery of the rotor 9; the axial front end part of the rotor shaft 10 is provided with a primary sun gear, the primary sun gear is in transmission connection with an output shaft 3 through a hollow planetary reducer 5, an internal thread matched with a screw rod 2 is arranged inside the output shaft 3, and the output shaft 3 is sleeved on the screw rod 2 and in transmission connection with the screw rod 2; and a pressure sensor is arranged in the planetary reducer or at the front end of the screw rod.

Specifically, in an electromechanical braking system, the rotation of the screw 2 is powered by a motor in an electric cylinder. The stator 8 generates a rotating magnetic field, and the rotor 9 is rotated by electromagnetic force. The rotor 9 receives electromagnetic force in a magnetic field generated by the stator 8 after being energized, and rotates, thereby converting electric energy into mechanical energy. The rotor shaft 10 is used to support and fix the rotor 9 and rotates together with the rotor 9 after being energized, converts electric energy into mechanical energy, and transmits mechanical energy for input or output. The rotor shaft 10 is decelerated through the hollow planetary reducer 5, and the output torque is increased while the output rotation speed of the motor is reduced, so that the braking force required during braking is met, and meanwhile, the parking torque required to be overcome by the parking mechanism is effectively reduced. The screw rod 2 is selectively rotated by the power provided by a motor in the electric cylinder, an output shaft 3 provided with internal threads is used as a nut, and the screw rod 2 and the output shaft 3 jointly convert rotary motion into linear motion. The screw rod 2 is connected with a braking device such as a clamp 19, and the like, and the screw rod 2 is pushed out to enable brake shoes and the like to be abutted against the braking wheel to generate braking force, so that the conversion process from electric energy to braking friction force is realized. In the hollow planetary reducer 5, the motor output shaft 3 and the sun gear of the hollow planetary reducer 5 are integrated, so that the installation space and the intermediate links of torque transmission can be reduced, the torque transmission efficiency is improved, the structure is compact, and the use of connecting fasteners such as bolts and keys is reduced; and the output shaft 3 of the hollow planetary reducer 5 is integrated with the nut, so that the transmission links are reduced, the transmission efficiency is improved, the structure is compact, and the use of connecting fasteners such as bolts, keys and the like is reduced. The rotor shaft 10 is sleeved on the screw rod 2, and the screw rod 2 can freely reciprocate in the hollow planetary reducer 5 through a large hollow structure. The pressure sensor 53 is integrated into the electric cylinder, saving installation space. Further, one axial side of the rotor 9 and the stator 8 is respectively provided with a rotor compression ring 11 and a stator compression ring 12, so as to realize positioning and prevent the rotor 9 and the stator 8 from moving along the axial direction.

As another specific embodiment, the axial front end of the screw rod 2 is provided with a push head 1. The push head 1 bears the thrust from the screw rod 2 and transmits the thrust to a brake shoe to realize braking, and the push head 1 is directly contacted with a working part, so that the load from the screw rod 2 can be borne and dispersed, the abrasion of the screw rod 2 is reduced, and the service life is prolonged.

As another specific embodiment, the primary sun gear and the rotor shaft 10 may be welded together or integrally formed. Preferably, the primary sun gear and the rotor shaft 10 are integrally formed. The integrally formed parts generally have higher structural strength and durability because without welded joints, the parts are less prone to fracture from the joints when subjected to pressure or load. And no welded joint may leak, with better sealing properties.

As another specific embodiment, a plurality of primary planet gears 51 are arranged on the periphery of the primary sun gear, and the plurality of primary planet gears 51 are connected through a primary planet carrier 52; the first-stage planetary gears 51 are in transmission connection with a second-stage sun gear 55, a plurality of second-stage planetary gears 54 are arranged on the periphery of the second-stage sun gear 55, and the second-stage planetary gears 54 are connected through a second-stage planetary carrier 56; the secondary planet 54 is connected to the output shaft 3. The speed reduction and torque increase device of the second-stage hollow planetary reducer 5 has large torque increase on the torque motor, reduces the dependence on the torque motor, and the power-off brake 18 of the parking mechanism is directly arranged on the motor rotor shaft 10 without passing through the speed reduction and torque increase device, so that the output torque is small, and the requirement on the power-off brake 18 is greatly reduced. Further, the outer sides of the primary planet gears 51 and the secondary planet gears 54 are correspondingly provided with a primary gear ring and a secondary gear ring, and the gear ring provides a fixed reference object for the planet gears, so that the planet gears can rotate around the sun gear to transmit torque. Further, positioning members are provided between the primary planet carrier 52 and the secondary planet carrier 56, and the positioning members can position the components in the axial direction and the radial direction, so that unnecessary movement or relative displacement of the components such as the sun gear, the planet gear, the ring gear and the like in the speed reducer in the axial direction can be prevented.

As another specific embodiment, the output shaft 3 is disposed axially in front of the primary sun gear, and a seal bearing 6 is disposed between the output shaft 3 and the primary sun gear in the axial direction. In particular, the seal bearing 6 is a rolling bearing, and can be equipped with an efficient seal to prevent leakage of lubricating oil.

As an embodiment of one specific pressure sensor, a spoke type pressure sensor 53 is disposed in the hollow planetary reducer 5. Specifically, the spoke-type pressure sensor 53 is disposed between the secondary planet carrier 56 and the primary planet carrier 52, and is sleeved on the secondary sun gear 55. The pressure sensor is arranged at the nut end, so that the force transmission path is reduced, and the real-time measurement is more accurate. The end of the screw rod 2 is pushed out and then acts on the brake shoe and the brake wheel forwards, in the braking process, the reaction force of the brake shoe can enable the screw rod 2 to move backwards, the screw rod 2 has a retreating trend under the reaction force, the reaction force is transmitted to the output shaft 3 through the screw rod 2, and then is transmitted to the spoke-type pressure sensor 53 through the secondary planet carrier 56 and the connecting component, and the braking force is obtained through data acquisition. Further, the spoke-type pressure sensor 53 is provided on the radially inner side of the positioning member, and the spoke-type pressure sensor 53 can be positioned.

As another specific pressure sensor embodiment, a screw push-pull sensor is arranged at the front end of the screw rod 2. The screw rod type push-pull sensor is directly arranged at the end head of the screw rod 2, the screw rod 2 is pushed out during braking and acts on one end of the screw rod type push-pull sensor, the other end of the screw rod type push-pull sensor is directly connected with the clamp 19, the brake shoe and the like, and the push-out force of the end of the screw rod 2 can be directly measured; when the electric brake cylinder is released, the screw rod 2 also pulls the screw rod type push-pull sensor net to push out and move in the opposite direction, and at the moment, the releasing force of the electric brake cylinder can be measured. Further, the screw type push-pull sensor is arranged on the push head 1.

As another specific embodiment, the rear end of the rotor shaft 10 is provided with a power-off brake 18 axially movable forward and backward by a brake mounting plate 14. The brake mounting plate 14 is fixedly arranged, and a transition bearing 15 is arranged between the brake mounting plate 14 and the rotor shaft 10. When the power-off brake 18 is in an electrified state, the backward magnetic force generated by the coil overcomes the forward elastic force of the spring, so that the friction plate and the brake mounting plate 14 are in a separated state, and the rotor shaft 10, the primary sun gear and other rotating parts can normally rotate; when the power-off brake 18 is powered off, the friction plate moves forward under the action of the spring force to abut against the brake mounting plate 14, and the generated friction force prevents the rotation of the rotor shaft 10 and the rotating parts such as the primary sun gear, and maintains the state when power is lost. Further, the internal structure of the power-off brake 18 is not shown in the drawings, but is well known to those skilled in the art.

As another specific embodiment, the rotor shaft 10 is provided with a rotary transformer 13. When the electromechanical braking electric cylinder works, the rotating part of the rotary transformer 13 rotates along with the sun gear, parameters such as the rotating speed and the rotating number of turns of the motor rotor 9 can be fed back in real time, and the motor is controlled and regulated in real time through collected data information, so that the output torque of the motor is kept in an optimal state.

As another specific embodiment, the motor further comprises a motor housing 7, wherein the screw rod 2, the rotor 9, the stator 8, the primary sun gear, the hollow planetary reducer 5 and the output shaft 3 are arranged in the motor housing 7, a front cover 4 is arranged on the axial front side of the motor housing 7, and the screw rod 2 penetrates out of the front cover 4 forwards; the rear side of the motor body is provided with a rear cover 17. The housing protects the motor, screw 2, guide rails, wires and other electronic components inside the electric cylinder from external environmental influences, such as dust, moisture, chemicals and mechanical damage. And can be as safe isolation layer, prevent that operating personnel from accidentally touching inside moving part and high-voltage power supply, reduce accident risk. The screw rod 2 can move back and forth through the front cover 4. Further, a plurality of steps for limiting each component are further arranged in the motor housing 7.

As another specific embodiment, the rear end portion of the screw 2 is provided with a drop-off preventing plate 16. The lead screw 2 can be prevented from moving forward too much to disengage from the output shaft 3 by the escape prevention plate 16.

A braking method of an electromechanical brake electric cylinder, comprising the steps of:

Step 1, a motor is powered on, a rotor 9 rotates according to a certain direction and a certain rotating speed, and the rotor 9 drives an output shaft 3 in transmission connection with the rotor 9 to rotate together;

Step 2.1, the rotor shaft 10 and the first-stage sun gear of the hollow planetary reducer 5 are in an integrated structure, the rotary motion of the rotor shaft 10 is transmitted to the first-stage sun gear, the first-stage sun gear transmits the rotary motion to the second-stage sun gear 55 through the first-stage driven wheel and the first-stage planet carrier 52, the rotating speed is reduced, the output torque is increased, and the output shaft 3 and the second-stage planet carrier 56 of the hollow planetary reducer 5 are in an integrated structure, so that the first-time speed reduction and moment increase are realized;

Step 2.2, the secondary sun gear 55 transmits the rotary motion to the output shaft 3 through the secondary driven wheel and the secondary planet carrier 56, so as to realize the second speed reduction and moment increase;

And 3, the output shaft 3 rotates, the screw rod 2 is driven to push out outwards through an internal thread structure serving as a screw rod nut to perform linear motion, and conversion from rotation to linear motion, torque to linear thrust is completed. The end of the screw rod 2 is connected with a clamp 19 mechanism, the outward pushing process of the screw rod 2 enables brake shoes and the like to be abutted against the brake wheel, braking force is generated, the conversion process from electric energy to braking friction force is achieved, at the moment, the output torque of the motor is adjusted through rotation and transformation of the pressure fed back by the pressure sensor, and accurate control of braking thrust is achieved.

As another specific embodiment, in the step 3, the front end of the screw rod 2 is pushed out and then acts on the brake shoe and the brake wheel, during the braking process, the reaction force of the brake shoe can make the screw rod 2 move backwards, the screw rod 2 has a tendency to retract under the reaction force, the reaction force is transmitted to the output shaft 3 through the screw rod 2, and then is transmitted to the spoke type pressure sensor 53 through the secondary planet carrier 56 and the connecting component, and the braking force is obtained through data acquisition.

In the step 3, as another specific embodiment, the screw rod type push-pull sensor is directly installed at the end of the screw rod 2, the screw rod 2 is pushed out during braking, the screw rod acts on one end of the screw rod type push-pull sensor, the other end of the screw rod type push-pull sensor is directly connected with the clamp 19, the brake shoe and the like, and the push-out force of the end of the screw rod 2 can be directly measured.

As another specific embodiment, the method further comprises the step 4 of powering off the power-off brake 18, wherein the magnetic force of the electromagnetic coil disappears, the friction plate is abutted against the brake mounting plate 14 under the action of the spring force, and generates friction force for preventing the rotation of the rotor shaft 10, the rotor shaft 10 cannot perform rotational movement, the push-out state of the screw rod 2 during braking is kept, and the braking force during braking is locked and kept all the time. The vehicle and the like are parked in place, and the parking braking effect is achieved.

Correspondingly, the method for relieving the electromechanical braking electric cylinder comprises the following steps of:

Step 1, a motor is powered on, a rotor 9 rotates according to a certain direction and a certain rotating speed, and the rotor 9 drives an output shaft 3 in transmission connection with the rotor 9 to rotate together;

Step 2.1, the rotor shaft 10 and a first-stage sun gear of the hollow planetary reducer are of an integrated structure, the rotary motion of the rotor shaft 10 is transmitted to the first-stage sun gear, the first-stage sun gear transmits the rotary motion to a second-stage sun gear 55 through a first-stage driven wheel and a first-stage planet carrier 52, the rotating speed is reduced, the output torque is increased, and the first-time speed reduction and torque increase are realized;

step 2.2, the secondary sun gear 55 transmits the rotary motion to the output shaft 3 through the secondary driven wheel and the secondary planet carrier 56, and the output shaft 3 and the secondary planet carrier 56 of the hollow planetary reducer 5 are of an integrated structure, so that the second speed reduction and torque increase are realized;

And 3, carrying out rotary motion on the output shaft 3, driving the screw rod 2 to retract through an internal thread structure serving as a screw rod nut, and carrying out linear motion to finish conversion from rotary motion to linear motion and torque to linear thrust. The brake shoes and the like are driven to be far away from the brake wheel, and the release process of braking is realized.

In the step 3, the screw rod 2 is pushed out during braking and acts on one end of the screw rod type push-pull sensor, the other end of the screw rod type push-pull sensor is directly connected with the clamp 19, the brake shoe and the like, and the screw rod 2 pulls the screw rod type push-pull sensor to move backwards, so that the magnitude of the relieving force of the electric brake cylinder is measured.

Step 0 is also included, in which the de-energized brake 18 remains energized and the solenoid generates a magnetic force to move the friction plate back away from the brake mounting plate 14 against the spring force, allowing the rotor shaft 10 to freely rotate.

The invention is not limited to the specific embodiments described above. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification, as well as to any novel one, or any novel combination, of the steps of the method or process disclosed.

Claims (10)

1. An electromechanical brake electric cylinder, characterized in that: the motor rotor comprises a screw rod (2), wherein a rotor shaft (10) is rotatably sleeved on the screw rod (2), a rotor (9) is sleeved on the periphery of the rotor shaft (10), and a stator (8) is sleeved on the periphery of the rotor (9); the axial front end part of the rotor shaft (10) is provided with a first-stage sun gear, the first-stage sun gear is connected with an output shaft (3) through a hollow planetary reducer in a transmission way, an internal thread matched with the screw rod (2) is arranged inside the output shaft (3), and the output shaft (3) is sleeved on the screw rod (2) and is in transmission connection with the screw rod (2); a pressure sensor is arranged in the hollow planetary reducer or at the front end of the screw rod (2).

2. The electro-mechanical brake cylinder of claim 1, wherein: the primary sun gear and the rotor shaft (10) are integrally formed.

3. The electro-mechanical brake cylinder of claim 1, wherein: the periphery of the primary sun gear is provided with a plurality of primary planet gears (51), and the plurality of primary planet gears (51) are connected through a primary planet carrier (52); the first-stage planetary gear (51) is in transmission connection with a second-stage sun gear (55), a plurality of second-stage planetary gears (54) are arranged on the periphery of the second-stage sun gear (55), and the plurality of second-stage planetary gears (54) are connected through a second-stage planetary carrier (56); the secondary planet wheel (54) is connected with the output shaft (3).

4. The electro-mechanical brake cylinder of claim 1, wherein: a spoke type pressure sensor (53) is arranged in the hollow planetary reducer.

5. The electro-mechanical brake cylinder of claim 1, wherein: the front end of the screw rod (2) is provided with a screw rod type push-pull sensor.

6. The electro-mechanical brake cylinder of claim 1, wherein: the rear end of the rotor shaft (10) is provided with a power-off brake (18) through a brake mounting plate (14).

7. A braking method of an electromechanical brake electric cylinder, comprising the steps of:

Step 1, the motor is powered on, the rotor (9) rotates according to a certain direction and a certain rotating speed, and the rotor (9) drives the output shaft (3) of the rotor (9) in transmission connection with the rotor to rotate together;

Step 2, the rotary motion of a rotor shaft (10) is transmitted to a first-stage sun gear, and the first-stage sun gear transmits the rotary motion to an output shaft (3) through a hollow planetary reducer to realize speed reduction and moment increase;

And 3, the output shaft (3) rotates, the screw rod (2) is driven to push outwards through an internal thread structure serving as a screw rod nut to perform linear motion, conversion from the rotation motion to the linear motion and from torque to linear thrust are completed, at the moment, the torque is output by a rotary change adjusting motor through the pressure fed back by a pressure sensor, and the accurate control of braking thrust is realized.

8. The electro-mechanical brake cylinder of claim 7 wherein: in the step 3, the front end of the screw rod (2) is pushed out and then acts on the brake shoe and the brake wheel forwards, and in the braking process, the reaction force of the brake shoe is transmitted to the output shaft (3) through the screw rod (2) and then transmitted to the spoke type pressure sensor (53) in the hollow planetary reducer, and the braking force is obtained through data acquisition.

9. The electro-mechanical brake cylinder of claim 7 wherein: in the step 3, the screw rod (2) is pushed out during braking and acts on one end of the screw rod type push-pull sensor, the other end of the screw rod type push-pull sensor is directly connected with the clamp (19), the brake shoe and the like, and the pushing force of the end of the screw rod (2) is directly measured.

10. The electro-mechanical brake cylinder of claim 7 wherein: the method further comprises the step 4 of powering off the power-off brake (18), the magnetic force of the electromagnetic coil disappears, the friction plate is attached to the brake mounting plate (14) under the action of the spring force, friction force for preventing the rotor shaft (10) from rotating is generated, the rotor shaft (10) cannot rotate, the push-out state of the screw rod (2) during braking is kept, and braking force during braking is locked and kept all the time.