Differential planetary roller screw structure

Abstract

The utility model discloses a differential type planetary roller screw structure which is characterized in that a planetary screw rod is positioned and mounted in a shell, a motor is in transmission connection with the planetary screw rod through a motor force transmission seat, a planetary nut is sleeved on the planetary screw rod, the planetary nut is in clearance fit with the planetary screw rod, and a walking space is formed between the planetary nut and the planetary screw rod. The planetary rollers are arranged in the walking space, the axes of the planetary rollers are parallel to the axis of the planetary screw rod, screw rod threads are arranged on the surface of the planetary screw rod, roller threads are arranged on the surfaces of the planetary rollers, nut threads are arranged on the inner surface of the planetary nut, and the screw rod threads and the nut threads are opposite in thread rotation direction. The roller threads are meshed and matched with the lead screw threads and the nut threads at the same time, the planetary roller can axially move in the walking space and rotate around the planetary lead screw, and the push head seat is fixed to the front end of the planetary nut and can stretch out of the front end of the shell. The utility model has the advantages of large thrust and high displacement precision.

Description

Technical Field

[0001] The utility model belongs to the technical field of planetary roller screws, and in particular relates to a differential planetary roller screw structure. Background Art

[0002] Planetary roller screws are highly efficient and precise transmission devices widely used in mechanical transmission systems. Combining the advantages of planetary gear mechanisms, they achieve high load carrying capacity and high-precision positioning by combining force and motion transmission. They offer higher transmission efficiency than traditional screws, typically exceeding 90%. Their compact design allows for high load capacity within limited space, making them widely used in automation equipment, robotics, industrial machinery, aerospace, and other fields.

[0003] With the development of society, the internal structures of automotive electrical machine boxes (EMBs) are increasing, and the space for electric cylinder installation is limited. However, the requirements for control accuracy and thrust output of electric cylinders are gradually increasing. Therefore, how to achieve high thrust output within this limited space is a technical challenge that needs to be solved in current electric cylinder design. In some electric cylinders, the main force transmission mechanism is a planetary roller screw. Therefore, research and development of how to achieve high thrust with a small stroke of the planetary roller screw is particularly important. Utility Model Content

[0004] The technical problem to be solved by the present invention is to provide a differential planetary roller screw structure in view of the deficiencies of the above-mentioned prior art.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the utility model is:

[0006] A differential planetary roller screw structure includes a housing, in which a motor, a motor force transmission seat, a planetary screw, a planetary roller, a planetary nut and a push head seat are installed. The planetary screw is positioned and installed in the housing, and the motor is connected to the planetary screw through the motor force transmission seat. The planetary nut is sleeved on the planetary screw, and the planetary nut and the planetary screw are clearance-matched. A walking space is formed between the planetary nut and the planetary screw. There are several planetary rollers, which are arranged in the walking space. The axis of the planetary roller is parallel to the axis of the planetary screw. The surface of the planetary screw is provided with a screw thread, the surface of the planetary roller is provided with a roller thread, and the inner surface of the planetary nut is provided with a nut thread. The thread rotation directions of the screw thread and the nut thread are opposite, and the roller thread is engaged with the screw thread and the nut thread at the same time. The planetary roller can move axially in the walking space and rotate around the planetary screw. The push head seat is fixed to the front end of the planetary nut, and the push head seat can extend from the front end of the housing.

[0007] To optimize the above technical solutions, specific measures taken also include:

[0008] The front and rear ends of the above-mentioned shell are both provided with openings, the front end of the shell is installed with an end cover A, and the rear end of the shell is installed with an end cover B. The end cover A and the end cover B respectively close the front and rear ends of the shell, and a through hole is provided on the end cover A for the push head seat to pass through.

[0009] The rear end of the planetary screw is provided with a mounting hole, and the motor force transmission seat is provided with a locking bolt, which can be inserted into the mounting hole to fix the planetary screw and the motor force transmission seat.

[0010] A thrust bearing is installed on the rear side of the above-mentioned motor force transmission seat. The thrust bearing and the rear side of the motor force transmission seat are circumferentially rotatable. The rear end of the thrust bearing is fixedly connected to the pressure sensor, and the pressure sensor is fixedly connected to the end cover B.

[0011] An encoder is installed on the above-mentioned motor force transmission seat, and the encoder is used to collect the number of rotations of the motor force transmission seat.

[0012] The front and rear ends of the motor force transmission seat are respectively in contact with the end cover A and the end cover B through cylindrical roller bearings. The cylindrical roller bearings enable the motor force transmission seat to rotatably cooperate with the end cover A and the end cover B.

[0013] The number of the planetary rollers is 4-6, and they are arranged around the planetary screw at equal arcs.

[0014] The pusher head seat is provided with a pusher head connection hole for connecting with an external structure.

[0015] The above-mentioned roller thread is an annular groove without a direction of rotation.

[0016] The above-mentioned motor is a frameless motor.

[0017] The beneficial effects of the utility model are:

[0018] 1. The differential planetary roller screw structure of the present invention utilizes a motor force transmission seat to position the planetary screw and transmits the motor's driving force through the motor force transmission seat, enabling the planetary screw to rotate in place. The planetary screw, planetary rollers, and planetary nut form a planetary reduction mechanism. During planetary screw rotation, the planetary rollers rotate around the planetary screw, converting rotation into axial movement of the planetary nut. During this process, the axial movement of the planetary nut is significantly reduced. Furthermore, the present invention sets the screw thread and nut threads in opposite directions and does not axially limit the planetary rollers, allowing axial movement of the planetary rollers. Therefore, when the planetary screw rotates, the planetary rollers and planetary nut move in opposite directions. For example, if the planetary screw drives the planetary rollers backward by 1 mm, while the rotation of the planetary rollers drives the planetary nut forward by 2 mm, the planetary nut will ultimately extend forward by 1 mm. By setting the screw thread and nut threads in opposite directions, the planetary nut stroke can be reduced while maintaining the motor torque, thereby generating greater thrust and improving screw displacement accuracy. The utility model is very suitable for application in EMBs that have extremely high requirements on space.

[0019] 2. The utility model can control the axial stroke of the planetary nut corresponding to each rotation of the planetary screw by adopting planetary screws and planetary nuts with different thread slopes. The utility model is also equipped with an encoder to accurately control the axial stroke of the planetary nut, which can greatly improve the application scenarios and working accuracy of the differential planetary roller screw structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the initial position state diagram of the utility model;

[0021] Figure 2 This is the maximum stroke position state diagram of the utility model;

[0022] Figure 3 This is a structural breakdown diagram of the utility model;

[0023] The figures are marked as follows: housing 1, motor 2, motor force transmission seat 3, planetary screw 4, planetary roller 5, walking space 5a, planetary nut 6, push head seat 7, end cover A8, end cover B9, thrust bearing 10, pressure sensor 11, encoder 12, locking bolt 13, cylindrical roller bearing 14, push head connecting hole 15. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is described and illustrated below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely used to explain this application and are not intended to limit this application. Based on the embodiments provided in this application, all other embodiments obtained by those of ordinary skill in the art without making any creative efforts are within the scope of protection of this application.

[0025] Obviously, the drawings described below are merely examples or embodiments of the present application. Those skilled in the art can, without inventive effort, apply the present application to other similar scenarios based on these drawings. Furthermore, it is also understood that, although the effort involved in such a development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, changes in design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as an insufficiency of the content disclosed in this application.

[0026] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it refer to independent or alternative embodiments that are mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described in this application may be combined with other embodiments unless there is a conflict.

[0027] Unless otherwise defined, the technical or scientific terms used in this application should have the ordinary meaning understood by a person of ordinary skill in the technical field to which this application belongs. The words "a", "an", "a", "the" and the like used in this application do not indicate a limit on quantity and may indicate the singular or plural. The terms "include", "comprise", "have" and any variations thereof used in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or units (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units that are inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like used in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The words "multiple" / "several" used in this application refer to two or more. "And / or" describes the association relationship between associated objects, indicating that three relationships can exist. For example, "A and / or B" can mean: A exists alone, A and B exist at the same time, or B exists alone. The character " / " generally indicates that the objects before and after are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific order for the objects.

[0028] like Figure 1-3 As shown, the utility model is a differential planetary roller screw structure, the main structure of which includes a housing 1, a motor 2, a motor force transmission seat 3, a planetary screw 4, a planetary roller 5, a planetary nut 6, a thrust head seat 7, an end cover A8, an end cover B9, a thrust bearing 10, a pressure sensor 11, an encoder 12, a cylindrical roller bearing 14, etc.

[0029] The housing 1 is an annular housing made of stainless steel. The front and rear ends of the housing 1 are covered by end caps A8 and B9 respectively. The motor 2 is connected to the motor transmission seat 3, and the motor transmission seat 3 is installed in the housing 1 through a cylindrical roller bearing 14.

[0030] The planetary screw 4, planetary roller 5 and planetary nut 6 constitute a planetary reduction structure, the planetary screw 4 is the driving part, the planetary nut 6 is the power output part, the planetary roller 5 is located in the walking space 5a formed by the planetary screw 4 and the planetary nut 6, the planetary roller 5 can move axially in the walking space 5a, the axis of the planetary roller 5 is parallel to the axis of the planetary screw 4, the surface of the planetary screw 4, the surface of the planetary roller 5 and the inner surface of the planetary nut 6 are all provided with threads, and the thread rotation directions of the screw thread and the nut thread are opposite, and the thread pitch is equal. The thread pitch of the roller thread of the planetary roller 5 is also the same as that of the screw thread and the nut thread, but the roller thread is a non-directional annular groove, and the roller thread engages with the screw thread and the nut thread respectively. The roller thread is set to 1 head, the screw thread is set to 3 heads, and the nut thread is set to 5 heads. The number of thread heads is the number of parallel threads on the working part.

[0031] A mounting hole is provided at the rear end of the planetary screw 4 , and a locking bolt 13 is installed on the motor force transmission seat 3 . The locking bolt 13 penetrates the mounting hole to fix the planetary screw 4 to the motor force transmission seat 3 .

[0032] An encoder 12 is mounted on the motor force transmission seat 3 to collect the number of rotations of the motor force transmission seat 3. The encoder 12 is connected to the vehicle computer outside the differential planetary roller screw structure and converts the number of rotations of the motor force transmission seat 3 into the extension length of the push head seat 7.

[0033] The working mode of the utility model is as follows:

[0034] like Figure 1 As shown, this is the initial position state where the push head seat 7 has not yet been pushed out. At this time, the motor 2 generates a magnetic field by energizing, driving the motor force transmission seat 3 to rotate, and the motor force transmission seat 3 drives the planetary screw 4 to rotate. The screw thread of the planetary screw 4 forces the planetary roller 5 to rotate circumferentially around the planetary screw 4, while also driving the planetary roller 5 to move to the right. The circumferential rotation of the planetary roller 5 drives the planetary nut 6 to move axially to the left. However, the distance that the planetary nut 6 moves axially to the left is greater than the distance that the planetary roller 5 moves to the right. Finally, the leftward displacement of the planetary nut 6 and the push head seat 7 = the distance that the planetary nut 6 moves to the left relative to the planetary roller 5 - the distance that the planetary roller 5 moves to the right. After the movement is completed, the state is as follows Figure 2 shown.

[0035] The utility model effectively reduces the stroke of the planetary nut by reversely designing the screw thread and the nut thread, thereby generating greater thrust and higher screw displacement accuracy.

[0036] It can be understood that the above specific description of the present invention is only used to illustrate the present invention and is not limited to the technical solution described in the calculation method implementation of the present invention. Ordinary technicians in this field should understand that the present invention can still be modified or replaced by equivalents to achieve the same technical effect; as long as the requirements of the calculation method are met, it is within the scope of protection of the present invention.

Claims

1. A differential planetary roller screw structure, comprising a housing (1), characterized in that: The housing (1) is provided with a motor (2), a motor transmission seat (3), a planetary screw (4), a planetary roller (5), a planetary nut (6) and a push head seat (7); the planetary screw (4) is positioned and installed in the housing (1); the motor (2) is connected to the planetary screw (4) through the motor transmission seat (3); the planetary nut (6) is sleeved on the planetary screw (4); the planetary nut (6) and the planetary screw (4) are clearance-matched; a walking space (5a) is formed between the planetary nut (6) and the planetary screw (4); the number of the planetary rollers (5) is several, and they are arranged in the walking space. In the space (5a), the axis of the planetary roller (5) is parallel to the axis of the planetary screw (4), the surface of the planetary screw (4) is provided with a screw thread, the surface of the planetary roller (5) is provided with a roller thread, the inner surface of the planetary nut (6) is provided with a nut thread, the screw thread and the nut thread have opposite thread rotation directions, the roller thread is engaged with the screw thread and the nut thread at the same time, the planetary roller (5) can move axially in the walking space (5a) and rotate around the planetary screw (4), the push head seat (7) is fixed to the front end of the planetary nut (6), and the push head seat (7) can extend from the front end of the housing (1).

2. The differential planetary roller screw structure according to claim 1, characterized in that: The front and rear ends of the shell (1) are both provided with openings, the front end of the shell (1) is installed with an end cover A (8), and the rear end of the shell (1) is installed with an end cover B (9), the end cover A (8) and the end cover B (9) respectively close the front and rear ends of the shell (1), and the end cover A (8) is provided with a through hole, and the through hole is for the push head seat (7) to pass through.

3. The differential planetary roller screw structure according to claim 2, characterized in that: The rear end of the planetary screw (4) is provided with a mounting hole, and the motor force transmission seat (3) is provided with a locking bolt (13). The locking bolt (13) can be inserted into the mounting hole to fix the planetary screw (4) and the motor force transmission seat (3).

4. The differential planetary roller screw structure according to claim 3, characterized in that: A thrust bearing (10) is installed on the rear side of the motor force transmission seat (3); the thrust bearing (10) and the rear side of the motor force transmission seat (3) are rotatably matched in the circumferential direction; the rear end of the thrust bearing (10) is fixedly connected to the pressure sensor (11); and the pressure sensor (11) is fixedly connected to the end cover B.

5. The differential planetary roller screw structure according to claim 4, characterized in that: An encoder (12) is installed on the motor force transmission seat (3), and the encoder (12) is used to collect the number of rotations of the motor force transmission seat (3).

6. The differential planetary roller screw structure according to claim 5, characterized in that: The front and rear ends of the motor force transmission seat (3) are respectively in contact with the end cover A (8) and the end cover B (9) through cylindrical roller bearings (14). The cylindrical roller bearings (14) enable the motor force transmission seat (3) to rotatably cooperate with the end cover A (8) and the end cover B (9).

7. The differential planetary roller screw structure according to claim 6, characterized in that: The number of the planetary rollers (5) is 4-6 and they are arranged around the planetary screw rod (4) with equal arcs.

8. The differential planetary roller screw structure according to claim 1, characterized in that: The pusher head seat (7) is provided with a pusher head connection hole (15) for connecting with an external structure.

9. The differential planetary roller screw structure according to claim 1, characterized in that: The roller thread is an annular groove without a rotation direction.

10. The differential planetary roller screw structure according to claim 1, characterized in that: The motor (2) is a frameless motor.

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