In-place protection mechanism for a driving device

Abstract

The present invention discloses a in-place protection mechanism for a driving device, which includes a splined lead screw shaft, a gear ring, a nut with a gear, an in-place protection assembly, and a lead screw gear with an internal spline; the in-place protection assemblies are symmetrically arranged at both ends of the splined lead screw shaft; a gear ring is arranged around the middle section of the splined lead screw shaft, an external spline is provided at the center of the splined lead screw shaft, and the external spline is meshed with the gear ring through the lead screw gear with an internal spline to form motion transmission; nuts with gears are also arranged on both sides of the external spline at the center of the splined lead screw shaft, the periphery of the nut with a gear is meshed with the gear ring, and the number of teeth on the periphery of the nut with a gear is different from the number of teeth of the lead screw gear with an internal spline; the internal thread of the nut with a gear is matched with the middle section of the splined lead screw shaft; when the splined lead screw shaft rotates forward or backward by a certain angle, one of the two nuts with gears can trigger the in-place protection assembly to form braking on the splined lead screw shaft, so as to achieve the purpose of limit protection.

Description

Technical Field

[0001] The present invention belongs to the technical field of mechanical transmission, and particularly relates to a position protection mechanism for a driving device. Background Art

[0002] The operation of systems such as aircraft cabin doors and slats is usually driven by a driving device to drive one or more groups of rotary actuators. During its movement, due to factors such as errors, it is difficult for the driving device to stop at an exact position. When its movement exceeds the specified range of the stroke, it may exert excessive force on the door or actuator. Obviously, this is not advisable. Therefore, a position protection mechanism is needed to ensure that the movement stroke of the system is within the specified range. The traditional design idea of position protection generally realizes position protection after judging the position through an electrical signal; for example, a position sensor or a displacement sensor is set, and the position information is collected by the sensor and sent to the control system in real time. The control system makes a judgment based on the position information. When the position information reaches the set threshold, the driving motor is cut off to achieve the purpose of position protection; when controlling by an electric control method, the critical point of protection is an instantaneous action, and the threshold set during the control process requires extremely precise accuracy. Otherwise, it is very difficult for the mechanism to stop at an exact position, and the situation of incomplete positioning may occur for the driving of aircraft cabin doors and slats.

[0003] In order to avoid the defect in reliability of electrical signal control in position protection, there are also improved designs of pure mechanical protection mechanisms proposed in this field. In some known mechanical braking protection devices, for example, US 4751988 provides an over-travel braking device for an aircraft drive system. The device includes a drive shaft with two gears of different tooth numbers at the distal end, which are simultaneously engaged with two gears of different tooth numbers on the driven shaft of the device, so as to provide a relative speed difference between the moving nut and the driven shaft to reduce the stroke. When the nut moves to either end, the jaws of the device are used to stop the movement of the moving nut, thereby restricting the overall movement of the system. However, the use of an external meshing form in this device results in a relatively long overall structure and inefficient use of space, and the "hard impact" caused by directly restricting the movement of the nut by the jaws is not considered, which may cause permanent damage to some parts. To solve this problem, some devices use elastic shock pads on the jaws to limit the damage caused by such collisions. During the collision between the nut and the jaws, the shock pad promotes the release of the energy generated by the collision through elastic deformation, reducing damage to the mechanism. However, such elastic shock pads are prone to wear. Summary of the Invention

[0004] The purpose of the present invention is to provide a position protection mechanism for a driving device, which can realize the restriction of the movement stroke range of the system by adopting a pure mechanical structure and avoid damage to structural parts.

[0005] Technical solution of the present invention: A position protection mechanism for a driving device, including a splined lead screw shaft, a one-way bearing, a splined shaft, a brake, a guiding end cover, a disc spring, a push plate, a gear ring, a pressing plate, a spacer sleeve, a nut with a gear, and a lead screw gear with an internal spline; wherein, the one-way bearing, the splined shaft, the brake, the guiding end cover, the disc spring, the push plate, the pressing plate, and the spacer sleeve are coaxially combined to form a position protection assembly, and the position protection assembly is symmetrically arranged at both ends of the splined lead screw shaft; a gear ring is arranged around the middle section of the splined lead screw shaft, an external spline is arranged at the center of the splined lead screw shaft, and the external spline is meshed with the gear ring through the lead screw gear with an internal spline to form motion transmission; on both sides of the external spline at the center of the splined lead screw shaft, there are also arranged nuts with gears, the periphery of the nut with a gear is meshed with the gear ring, and the number of teeth on the periphery of the nut with a gear is different from the number of teeth of the lead screw gear with an internal spline; the internal thread of the nut with a gear is matched with the middle section of the splined lead screw shaft; when the splined lead screw shaft rotates forward or backward by a certain angle, one of the two nuts with gears can trigger the position protection assembly to form braking on the splined lead screw shaft, so as to achieve the purpose of limit protection.

[0006] Further, the splined lead screw shaft and the lead screw gear with an internal spline are in spline fit, and their axes are not on the same straight line. While driving the gear ring to rotate, it drives the nut with a gear to move, and the nut with a gear has a certain rotational speed difference relative to the splined lead screw shaft.

[0007] Further, external teeth are machined on the outer ring of the nut with a gear. In order to ensure meshing with the gear ring, a modification method is adopted to ensure a difference in the number of teeth from the lead screw gear with an internal spline.

[0008] Further, in the position protection assembly, for the one-way bearing, the splined shaft, the brake, the guiding end cover, the disc spring, the push plate, the pressing plate, and the spacer sleeve, the splined shaft is sleeved at the end of the splined lead screw shaft, and a one-way bearing is arranged between the two; the brake is sleeved around the splined shaft, the guiding end cover is connected to the brake and limits the pressing plate within the guiding end cover; the spacer sleeve is installed on the splined lead screw shaft, the push plate is matched with the spacer sleeve, and the disc spring is arranged between the push plate and the pressing plate; the end of the nut with a gear is in extrusion fit with the push plate to trigger the actuation of the position protection assembly.

[0009] Further, symmetric long grooves are machined in the guiding end cover and are matched with the protrusions on the outer circle of the pressing plate to ensure that the pressing plate can only move axially without rotation.

[0010] Further, steps are machined on both the splined lead screw shaft and the push plate. Under normal circumstances, under the thrust of the disc spring and with the limitation of the spacer sleeve, the two steps can limit the axial movement of the push plate and play a positioning role.

[0011] Further, a disc spring is placed between the pressure plate and the push plate. When the nut with a gear impacts the push plate, the disc spring compresses to absorb the energy generated by the collision.

[0012] Further, the brake housing is machined with internal splines that cooperate with the external splines of the static friction plate; one end of the spline shaft is provided with external splines that cooperate with the internal splines of the dynamic friction plate, and the other end is internally provided with a flat keyway that cooperates with the flat keyway of the outer ring of the one-way bearing; the splined lead screw shaft is also provided with a flat keyway that cooperates with the flat keyway of the inner ring of the one-way bearing.

[0013] Further, the two one-way bearings are symmetrically installed to ensure that when rotating in one direction, the torque can be transmitted from the splined lead screw shaft to the spline shaft, and the transmission of torque can be cut off at the other end.

[0014] Further, the two nuts with gears are respectively at the end of the lead screw gear close to the internal splines and at the end of the lead screw gear far from the internal splines, so as to ensure that no matter whether the mechanism rotates forward or backward, there is a nut that can impact the pressure plate, thereby activating the braking function of the brake and restricting the movement of the mechanism.

[0015] Advantages of the present invention: The present invention adopts the form of combining internal meshing gears and ball screws. Compared with traditional ball screws, under the same working conditions, it can effectively shorten the moving stroke of the nut; at the same time, a disc spring is used to absorb the energy generated by the collision through elastic deformation, reducing damage to the mechanism.

[0016] A position protection mechanism for a driving device specifically designed by the present invention has a compact overall structure and adopts an approximately symmetrical distribution to ensure that the product can operate normally under both forward and reverse rotations. By adopting the form of combining internal meshing gears and ball screws to convert rotational motion into linear motion, compared with the traditional lead screw nut structure, it can effectively shorten the stroke. At the same time, a disc spring is used to absorb the impact generated by mechanical collisions, reducing damage to the structure and playing a certain limiting and protecting role. A one-way bearing is used to cut off or transmit torque according to the movement direction of the product, and combined with static and dynamic friction plates to achieve the effect of speed reduction and braking. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of the mechanical position protection mechanism of the present invention;

[0018] Figure 2 is a schematic diagram of the cooperation between the lead screw gear with internal splines and the gear ring. DETAILED DESCRIPTION OF THE INVENTION

[0019] The following further describes the specific implementation of the present invention in conjunction with the drawings.

[0020] As shown in the atta Figure 1As shown in the figure, the present invention is a position protection mechanism for a driving device, including a splined lead screw shaft 1, two one-way bearings (2, 2'), two splined shafts (3, 3'), two brakes (4, 4'), two guiding end covers (5, 5'), two groups of disc springs (6, 6'), two push plates (7, 7'), a gear ring 8, two pressing plates (9, 9'), two spacer sleeves (10, 10'), two nuts with gears (11, 11'), and a lead screw gear 12 with internal splines; wherein, the one-way bearings, splined shafts, brakes, guiding end covers, disc springs, push plates, pressing plates, and spacer sleeves are coaxially combined to form a position protection assembly, and the position protection assembly is symmetrically arranged at both ends of the splined lead screw shaft; a gear ring is arranged on the outer periphery of the middle section of the splined lead screw shaft, and an external spline is arranged at the center of the splined lead screw shaft, and the external spline meshes with the gear ring through the lead screw gear with internal splines to form motion transmission; on both sides of the external spline at the center of the splined lead screw shaft, nuts with gears are also arranged, the outer periphery of the nuts with gears meshes with the gear ring, and the number of teeth on the outer periphery of the nuts with gears is different from the number of teeth of the lead screw gear with internal splines; the internal thread of the nuts with gears cooperates with the middle section of the splined lead screw shaft; when the splined lead screw shaft rotates forward or backward by a certain angle, one of the two nuts with gears will surely trigger the position protection assembly to form braking on the splined lead screw shaft, so as to achieve the purpose of limit protection.

[0021] This device is composed of two sets of symmetrical structures. During normal operation, an external power source drives the rotation of the splined lead screw shaft 1, and the lead screw gear 12 with internal splines that is spline-fitted with the splined lead screw shaft 1 drives the gear ring 8 to rotate. At the same time, the gear ring 8 will also drive the cooperating nuts with gears 11, 11'. Generally speaking, in the case where only the lead screw can rotate, restricting the rotation of the nut, the nut will move along the axial direction of the lead screw, or only the lead screw is fixed, and the nut can still maintain linear motion while rotating. In order to utilize this characteristic and at the same time reduce the overall stroke, in the case of adopting the above-mentioned structural form, there is a difference in the number of teeth between the nuts with gears 11, 11' and the lead screw gear 12 with internal splines. In order to ensure meshing with the same gear ring, a modification method is adopted. In this way, it can be ensured that both the nut and the lead screw can rotate in the same direction at the same time. However, due to the speed difference, the nut always lags behind or is ahead of the rotational speed of the lead screw. Utilizing the relative motion relationship, at this time, the nut will move along the axial direction of the lead screw at a relatively small moving speed.

[0022] To ensure that when the device rotates in both forward and reverse directions, a nut with a gear can reach the braking end to play a role in stroke protection, two nuts with gears need to be arranged at the spline positions of the splined lead screw shaft 1 close to and far from the spline respectively, and a certain stroke is reserved to ensure that the balls will not slide out of the raceway. Assume that when the splined lead screw shaft 1 rotates forward, the nut 11 with a gear moves to the left until it pushes the push plate 7 to compress the disc spring 6, and then the pressure plate 9 moves, causing the moving friction plate and the static friction plate in the brake to contact. When the braking torque is greater than the output torque, the rotation of the spline shaft 3 that cooperates with the moving friction plate is restricted. Since the spline shaft 3 is connected to the one-way bearing 2 through a flat key, and the one-way bearing 2 is also connected to the splined lead screw shaft 1 through a flat key, because the rotation direction of the splined lead screw shaft 1 at this time is the direction in which the one-way bearing 2 is locked, the torque on the splined lead screw shaft 1 can be transmitted to the spline shaft 3. When the spline shaft 3 is torque-limited, the splined lead screw shaft 1 also stops moving. At this time, the energy generated by the impact is absorbed by the disc spring 6 in the form of deformation. When the splined lead screw shaft 1 moves in the reverse direction, the rotation direction at this time is the direction in which the one-way bearing 2 can rotate freely. Since the splined lead screw shaft 1 is not directly connected to the brake and, under the action of the one-way bearing 2, there is no need to apply pressure to reduce the normal pressure between the friction plates, thus ensuring the reverse movement of the splined lead screw shaft 1.

[0023] To help understand the principle of the above lead screw nut, assume that the number of teeth on the nut 11 with a gear is one less than the number of teeth on the splined lead screw gear 12 with internal splines, and both are meshed with the same tooth ring 8 (for example, if the splined lead screw gear 12 with internal splines has 48 teeth, the nut 11 with a gear has 47 teeth, and the tooth ring 8 has 65 teeth, and profile shifting is used to ensure the same center distance). Let n be the number of turns of the splined lead screw shaft 1, n 1 be the number of turns of the tooth ring 8, and n 2 be the number of turns of the nut 11 with a gear. Then the effective number of turns of the nut gear 11 with a gear moving along the splined lead screw shaft 1 is equal to n 2 -n.

[0024]

[0025]

[0026] The effective number of turns is obtained.

[0027]

[0028] Compared with a ball screw with the same lead, this greatly reduces the moving stroke of the nut.

[0029] One end of the in-place protection mechanism of the present invention is installed at the output shaft end of the driving device, and the other end is installed at the input end of the rotary actuator. During normal operation, the driving device drives the in-place protection mechanism of the present invention to move, thereby driving systems such as the aircraft cabin door and the slat / flap to work. Through precise calculation, it is ensured that when systems such as the cabin door and the slat / flap approach the limit of the movement stroke, the nut with a gear of this mechanism triggers the in-place protection component, locking the splined lead screw shaft to play a role in stroke protection.

[0030] The overall structure layout of the present invention is reasonable. The symmetrical design at both ends and the asymmetric installation of the nut ensure that the product meets the usage requirements of forward and reverse rotation. Utilizing the characteristics of the disc spring with high stiffness and strong shock absorption ability, the impact generated during product impact is absorbed, reducing the probability of mechanism damage. In addition, relying on the characteristics of the one-way bearing to cut off or transmit torque, and combining with dynamic and static friction plates to achieve the effect of speed reduction and braking, it can effectively protect the normal operation of the system.

[0031] The present invention is described in detail above in combination with the accompanying drawings of the specification or specific implementation cases. It should be noted that some (but not all) of the public examples are shown in the drawings. In fact, many different examples can be described and these examples should not be understood as being limited to the examples described herein. On the contrary, these examples are described to better demonstrate the positive effects of the present invention. Those parts not elaborated in the text are regarded as well-known technologies or conventional technical means in the art.

Claims

1. In-place protection mechanism for a driving device, characterized in that, the in-place protection mechanism includes a splined lead screw shaft, a one-way bearing, a splined shaft, a brake, a guiding end cover, a disc spring, a push plate, a gear ring, a pressing plate, a spacer sleeve, a nut with a gear, and a lead screw gear with an internal spline; among them, the one-way bearing, the splined shaft, the brake, the guiding end cover, the disc spring, the push plate, the pressing plate, and the spacer sleeve are coaxially combined to form an in-place protection assembly, and the in-place protection assembly is symmetrically arranged at both ends of the splined lead screw shaft; a gear ring is arranged around the middle section of the splined lead screw shaft, and an external spline is provided at the center of the splined lead screw shaft. The external spline meshes with the gear ring through the lead screw gear with an internal spline to form motion transmission; on both sides of the external spline at the center of the splined lead screw shaft, there are also nuts with gears arranged. The outer periphery of the nut with a gear meshes with the gear ring, and the number of teeth on the outer periphery of the nut with a gear is different from the number of teeth of the lead screw gear with an internal spline; the internal thread of the nut with a gear cooperates with the middle section of the splined lead screw shaft; when the splined lead screw shaft rotates forward or backward by a certain angle, one of the two nuts with gears can trigger the in-place protection assembly to form braking on the splined lead screw shaft to achieve the purpose of limit protection.

2. The in-place protection mechanism for a driving device according to claim 1, characterized in that, the splined lead screw shaft and the lead screw gear with an internal spline are in spline fit, and their axes are not on the same straight line. While driving the gear ring to rotate, it drives the nut with a gear to move, and the nut with a gear has a certain rotational speed difference relative to the splined lead screw shaft.

3. The in-place protection mechanism for a driving device according to claim 2, characterized in that, the outer ring of the nut with a gear is machined with external teeth. In order to ensure meshing with the gear ring, a modification method is adopted to ensure a difference in the number of teeth from the lead screw gear with an internal spline.

4. The in-place protection mechanism for a driving device according to claim 1, characterized in that, the in-place protection assembly is composed of a one-way bearing, a splined shaft, a brake, a guiding end cover, a disc spring, a push plate, a pressing plate, and a spacer sleeve. The splined shaft is sleeved at the end of the splined lead screw shaft, and a one-way bearing is arranged between them. The brake is sleeved around the splined shaft, and the guiding end cover is connected to the brake and limits the pressing plate within the guiding end cover; the spacer sleeve is installed on the splined lead screw shaft, the push plate is matched with the spacer sleeve, and the disc spring is arranged between the push plate and the pressing plate; the end of the nut with a gear is in extrusion fit with the push plate to trigger the actuation of the in-place protection assembly.

5. The in-place protection mechanism for a driving device according to claim 4, characterized in that, symmetric long grooves are machined in the guiding end cover and cooperate with the protrusions on the outer ring of the pressing plate to ensure that the pressing plate can only move axially without rotation.

6. The in-place protection mechanism for a driving device according to claim 4, characterized in that, both the splined lead screw shaft and the push plate are machined with steps. Under normal circumstances, under the thrust of the disc spring and with the limit of the spacer sleeve, the two steps can limit the axial movement of the push plate and play a positioning role.

7. The in-place protection mechanism for a driving device according to claim 4, characterized in that, The brake housing is machined with an internal spline that mates with the external spline of the static friction plate; one end of the spline shaft is provided with an external spline that mates with the internal spline of the dynamic friction plate, and the other end is internally provided with a flat keyway that mates with the flat keyway of the outer ring of the one-way bearing; the splined lead screw shaft is also provided with a flat keyway that mates with the flat keyway of the inner ring of the one-way bearing.

8. The in-place protection mechanism of the drive device according to claim 4, characterized in that, the two one-way bearings are symmetrically installed to ensure that when rotating in one direction, the torque can be transmitted from the splined lead screw shaft to the spline shaft, and the torque transmission can be cut off at the other end.

9. The in-place protection mechanism of the drive device according to claim 4, characterized in that, the two nuts with gears are respectively at the end of the lead screw gear close to the internal spline and at the end of the lead screw gear far from the internal spline, so as to ensure that no matter whether the mechanism rotates forward or backward, there is a nut that can hit the pressure plate, thereby activating the braking function of the brake and restricting the movement of the mechanism.

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