ES2990095A1 - Rotary driving mechanism, boom, and engineering machinery - Google Patents

Abstract

Disclosed are a rotary driving mechanism, a boom, and engineering machinery. The rotary driving mechanism comprises an annular piston (10) and a stator (20, 30); the annular piston (10) is provided with a piston tooth portion (11, 13) having a protruding curved tooth surface and a piston tooth portion (12, 14) having an inclined flat tooth surface; the stator (20, 30) is provided with a stator tooth portion (21, 31) having a protruding curved tooth surface and a stator tooth portion (22, 32) having an inclined flat tooth surface; the annular piston (10) can be driven to move axially with respect to the stator (20, 30). The combination of engagement of the curved tooth surface and engagement of the flat tooth surface can ensure smooth transmission at an initial engagement stage, so that the noise is smaller, and the axial movement can be converted into uniform rotation in a subsequent engagement state, thereby providing more stable torque output.

Description

DESCRIPTION

Rotary drive mechanism, boom and engineering machinery

CROSS REFERENCE TO A RELATED APPLICATION

This application claims the benefits of Chinese Patent Application No.

202210259497.3 filed on March 16, 2022, the content of which is incorporated herein by reference.

FIELD

The present description relates to the field of booms, in particular to a rotary drive mechanism, a boom and engineering machinery.

BACKGROUND

A boom is generally composed of a plurality of boom sections hinged together, and is folded and unfolded under the driving actions of the oil cylinders of the respective boom sections. The relative rotation angle between every two adjacent boom sections is a key factor affecting the flexibility and working range of the boom. The larger the relative rotation angle between every two adjacent boom sections, the larger the flexibility and working range of the boom, and vice versa.

At present, in most boom systems, the maximum relative rotation angle between two adjacent boom sections is not more than 220°, which sometimes makes it difficult to meet the material distribution conditions in complex construction environments; especially, when the boom system needs to go around obstacles, the limited relative rotation angle makes it difficult for the boom system to be deployed in a desired attitude. In addition, due to the connections of the boom sections formed by the linkage between the oil cylinders and the curved plates, the movement pattern of the boom is very simple when deployed, specifically, the boom sections can only be deployed in a clockwise or counterclockwise direction; in addition, in order to fold the boom sections when the relative rotation angle of the boom sections is very large, the boom sections can be rotated at a very large angle in the opposite direction, consequently, the flexibility and working efficiency of the boom are seriously compromised.

In addition, the relative angular velocity between boom sections is not proportional to the stroke of the oil cylinder. The relative angular velocity between boom sections varies with the varying relative rotation angle. In addition, since the boom sections are very long, an "amplification" effect will form at the ends, and such fluctuations will significantly decrease the stability and accuracy of the boom ends.

SUMMARY

An object of the present disclosure is to provide a rotary drive mechanism for solving the problems of uneven torque output and unstable rotation speed.

To achieve the above object, in one aspect, the present disclosure provides a rotary drive mechanism, comprising an annular piston and a stator, wherein the annular piston is provided with a piston tooth portion having a protruding curved tooth surface and a piston tooth portion having an inclined flat tooth surface; the stator is provided with a stator tooth portion having a protruding curved tooth surface and a stator tooth portion having an inclined flat tooth surface; the annular piston is driveable to move axially relative to the stator, and the annular piston engages with the stator tooth portion having the protruding curved tooth surface through the piston tooth portion having the protruding curved tooth surface first, and then engages with the stator tooth portion having the inclined flat tooth surface through the piston tooth portion having the inclined flat tooth surface, so that the annular piston is driven to rotate circumferentially.

Optionally, the stator comprises a first annular stator and a second annular stator, and the annular piston is arranged between the first stator and the second stator.

Optionally, a first axial end of the annular piston is provided with a first piston tooth portion and a second piston tooth portion, and a second axial end of the annular piston is provided with a third piston tooth portion and a fourth piston tooth portion; the first stator is provided with a first stator tooth portion capable of engaging with the first piston tooth portion and a second stator tooth portion capable of engaging with the second piston tooth portion; the second stator is provided with a third stator tooth portion capable of engaging with the third piston tooth portion and a fourth stator tooth portion capable of engaging with the fourth piston tooth portion; the first piston tooth portion and the first stator tooth portion have a protruding curved tooth surface respectively; the second piston tooth portion and the second stator tooth portion have an inclined flat tooth surface respectively; the third piston tooth portion and the third stator tooth portion have a protruding curved tooth surface respectively; and the fourth piston tooth portion and the fourth stator tooth portion have an inclined flat tooth surface respectively, where the annular piston can be driven to reciprocate axially, where the first piston tooth portion first engages with the first stator tooth portion and then the second piston tooth portion engages with the second stator tooth portion; the third piston tooth portion first engages with the third stator tooth portion and then the fourth piston tooth portion engages with the fourth stator tooth portion, so that the annular piston is urged to rotate.

Optionally, the first piston tooth portion, the first stator tooth portion, the third piston tooth portion and the third stator tooth portion have an involute tooth surface, respectively.

Optionally, the first piston tooth portion and the second piston tooth portion are located on an inner side and an outer side radially, respectively, and the third piston tooth portion and the fourth piston tooth portion are located on the inner side and the outer side radially, respectively.

Optionally, the first piston tooth portion and the second piston tooth portion are in correspondence with each other and their center lines are aligned with each other; the first stator tooth portion and the second stator tooth portion are in correspondence with each other and their center lines are aligned with each other; the third piston tooth portion and the fourth piston tooth portion are in correspondence with each other and their center lines are aligned with each other; and the third stator tooth portion and the fourth stator tooth portion are in correspondence with each other and their center lines are aligned with each other.

Optionally, the center lines of the first stator tooth portion and the second stator tooth portion are staggered from the center lines of the third stator tooth portion and the fourth stator tooth portion; and the center lines of the first piston tooth portion and the second piston tooth portion are aligned with the center lines of the third piston tooth portion and the fourth piston tooth portion.

Optionally, a distance between tooth tips of the first piston tooth portion and the second piston tooth portion and tooth tips of the third piston tooth portion and the fourth piston tooth portion is greater than a distance between tooth tips of the first stator tooth portion and the second stator tooth portion and tooth tips of the third stator tooth portion and the fourth stator tooth portion, and less than a distance between tooth tips of the first stator tooth portion and the second stator tooth portion and tooth roots of the third stator tooth portion and the fourth stator tooth portion, and less than a distance between tooth roots of the first stator tooth portion and the second stator tooth portion and tooth tips of the third stator tooth portion and the fourth stator tooth portion.

As an option, the rotary drive mechanism comprises two axially arranged sets of first stators, second stators and annular pistons, the first stators and the second stators in the two sets being fixed relative to each other, and the two annular pistons in the two sets being fixed relative to each other circumferentially and movable relative to each other axially.

Optionally, the center lines of the first piston tooth portions of the two annular pistons are staggered relative to each other.

Optionally, the rotary drive mechanism comprises an inner ring, the two annular pistons are axially slidably mounted in the inner ring, and the two annular pistons are fixed circumferentially with respect to the inner ring.

Furthermore, the present disclosure also provides a pen, which is provided with the rotary drive mechanism described in the previous solution.

Furthermore, the present description also provides engineering machinery, provided with the boom described in the previous solution.

With the above technical solution, the combination of curved tooth surface engagement and flat tooth surface engagement can ensure smooth transmission at an early engagement stage, so that the noise is lower and the axial motion can be converted into uniform rotation at a later engagement stage, thus providing a more stable torque output.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a partial schematic view of the rotary drive mechanism according to one embodiment of the present disclosure;

Fig. 2 is an exploded view of the rotary drive mechanism according to the embodiment of the present disclosure;

Fig. 3 is a perspective view of the annular piston according to the embodiment of the present disclosure;

Fig. 4 is a schematic structural view of the coupling between the annular piston and the stator according to the embodiment of the present disclosure;

Fig. 5 is a flow chart of the engagement between the toothed portions of the annular piston and the toothed portions of the stator according to the embodiment of the present disclosure; and

Fig.6 and 7 are flow diagrams of the rotation of the annular piston relative to the stator in two different directions, respectively.

Reference numbers:

10: annular piston; 11: first piston tooth portion; 12: second piston tooth portion; 13: third piston tooth portion; 14: fourth piston tooth portion; 20: first stator; 21: first stator tooth portion; 22: second stator tooth portion; 30: second stator; 31: third stator tooth portion; 32: fourth stator tooth portion; 40: inner ring; 50: end cap.

DETAILED DESCRIPTION

Some embodiments of the present disclosure will now be detailed with reference to the accompanying drawings. It is to be understood that the embodiments described in this invention are provided only to describe and explain the present disclosure, but are not intended to constitute any limitation of the present disclosure.

The present disclosure provides a rotary drive mechanism, comprising an annular piston 10 and a stator, wherein the annular piston 10 is provided with a piston tooth portion having a protruding curved tooth surface and a piston tooth portion having an inclined flat tooth surface; the stator is provided with a stator tooth portion having a protruding curved tooth surface and a stator tooth portion having an inclined flat tooth surface; the annular piston 10 is actuatable to move axially relative to the stator, and the annular piston 10 engages with the stator tooth portion having the protruding curved tooth surface through the piston tooth portion having the protruding curved tooth surface first, and then engages with the stator tooth portion having the inclined flat tooth surface through the piston tooth portion having the inclined flat tooth surface, so that the annular piston 10 is driven to rotate circumferentially.

In the two tooth portions of the annular piston 10, the tooth surface of one tooth portion is a curved tooth surface and in a protruding shape, while the tooth surface of the other tooth portion is a flat tooth surface. Accordingly, the tooth surface of one tooth portion of the stator is a curved tooth surface protruding outward, and the tooth surface of the other tooth portion of the stator is a flat tooth surface. The curved tooth surface of the annular piston 10 is engaged with the curved tooth surface of the stator, and the flat tooth surface of the annular piston 10 is engaged with the flat tooth surface of the stator.

Tooth surfaces refer to the surfaces that are engaged with each other when two parts of the teeth are engaged with each other. The axial direction refers to the axial direction of the annular piston 10, and the circumferential direction refers to the circumferential direction of the annular piston 10.

In particular, the annular piston 10 can be driven to move axially, for example, by hydraulic pressure or air pressure, etc., so that the toothed portions at the two ends of the annular piston 10 are engaged and disengaged from the toothed portions of the stator, respectively. In the two-tooth engagement method, the tooth tip of the stator is slightly stepped from the tooth tip of the annular piston 10, and the tooth on the stator can guide the tooth on the annular piston 10 to move relatively circumferentially, so that the tooth tip of the annular piston 10 moves to align with the tooth root of the stator tooth, whereby the annular piston 10 rotates relative to the stator.

As shown in Fig. 5, when the annular piston 10 is engaged with the stator (for example, the first stator 20), the annular piston 10 is initially engaged with the first stator 20 by means of tooth engagement between the curved tooth surfaces, which are existing tooth structures, and such a design is helpful for reducing wear between the tooth portions and realizing stable transmission, and has advantages such as labor saving, durability and low noise, etc. Of course, even if the axial relative motion of the two components is uniform, the circumferential relative motion caused by the engagement is not uniform. Next, the second piston tooth portion 12 is engaged with the second stator tooth portion 22. The two teeth are irregular structures different from the existing teeth, that is, the tooth surface of each tooth is flat and forms an angle with respect to the axial direction (or the tooth center line). When the axial relative motion is uniform, the circumferential motion of the annular piston 10 relative to the first stator 20 is also uniform, i.e., uniform rotation is performed.

The stator comprises a first annular stator 20 and a second annular stator 30, and the annular piston 10 is disposed between the first stator 20 and the second stator 30. The annular piston 10 is axially movable between the first stator 20 and the second stator 30, and the annular piston 10 is driven to rotate circumferentially by means of the engagement between the tooth portions, thereby realizing continuous rotation.

Specifically, a first axial end of the annular piston 10 is provided with a first piston tooth portion 11 and a second piston tooth portion 12, and a second axial end of the annular piston 10 is provided with a third piston tooth portion 13 and a fourth piston tooth portion 14; the first stator 20 is provided with a first stator tooth portion 21 engageable with the first piston tooth portion 11 and a second stator tooth portion 22 engageable with the second piston tooth portion 12; the second stator 30 is provided with a third stator tooth portion 31 engageable with the third piston tooth portion 13 and a fourth stator tooth portion 32 engageable with the fourth piston tooth portion 14; the first piston tooth portion 11 and the first stator tooth portion 21 have a protruding curved tooth surface, respectively; The second piston tooth portion 12 and the second stator tooth portion 22 have an inclined flat tooth surface respectively; the third piston tooth portion 13 and the third stator tooth portion 31 have a protruding curved tooth surface respectively; and the fourth piston tooth portion 14 and the fourth stator tooth portion 32 have an inclined flat tooth surface respectively, where the annular piston 10 can be driven to reciprocate axially, where the first piston tooth portion 11 engages with the first stator tooth portion 21 first, and then the second piston tooth portion 12 engages with the second stator tooth portion 22; the third piston tooth portion 13 engages with the third stator tooth portion 31 first, and then the fourth piston tooth portion 14 engages with the fourth stator tooth portion 32, so that the annular piston 10 is urged to rotate.

The annular piston 10, the first stator 20 and the second stator 30 can be formed in an essentially tubular shape, respectively, and are arranged coaxially. The rotation of the annular piston 10 is the rotation around its central axis.

As shown in Fig. 5, when the annular piston 10 engages with the first stator 20, the first piston tooth portion 11 first engages with the first stator tooth portion 21, that is, the annular piston 10 initially engages with the first stator 20 by means of tooth engagement between the curved tooth surfaces, which are existing tooth structures, and such a design is helpful for reducing wear between the tooth portions and realizing stable transmission, and has advantages such as labor saving, durability and low noise, etc. Of course, even if the axial relative motion of the two components is uniform, the circumferential relative motion caused by the engagement is not uniform. Next, the second piston tooth portion 12 engages with the second stator tooth portion 22. The two teeth are irregular structures different from the existing teeth, that is, the tooth surface of each tooth is flat and forms an angle with respect to the axial direction (or the tooth center line). When the axial relative motion is uniform, the circumferential motion of the annular piston 10 relative to the first stator 20 is also uniform, i.e., uniform rotation is performed.

It should be noted that, in the stage where the first piston tooth portion 11 engages with the first stator tooth portion 21, the second piston tooth portion 12 does not engage with the second stator tooth portion 22; and when the second piston tooth portion 12 begins to engage with the second stator tooth portion 22, the first piston tooth portion 11 begins to disengage from the first stator tooth portion 21.

The engagement of the third piston tooth portion 13 and the fourth piston tooth portion 14 of the annular piston 10 with the second stator 30 is essentially the same as the engagement of the annular piston 10 with the first stator as described above, and will not be detailed further here.

Optionally, the first piston tooth portion 11, the first stator tooth portion 21, the third piston tooth portion 13 and the third stator tooth portion 31 have an involute tooth surface, respectively. In other words, the curved tooth surface is an involute tooth surface, i.e., the tooth surface structure of teeth in existing gears.

The first piston tooth portion 11 and the second piston tooth portion 12 are located on an inner side and an outer side radially, respectively, and the third piston tooth portion 13 and the fourth piston tooth portion 14 are located on the inner side and the outer side radially, respectively. As shown in Fig. 1-4, the axial ends of the annular piston 10 are provided with a toothed portion respectively, and the toothed portion at each end is composed of an inner layer and an outer layer. Accordingly, the two stators to be meshed with the annular piston 10 are also respectively provided with a toothed portion composed of an inner layer and an outer layer. It should be noted that the tooth portion having a curved tooth surface or the tooth portion having a flat tooth surface may be arranged on the outer layer or the inner layer.

The first piston tooth portion 11 and the second piston tooth portion 12 are in correspondence with each other and their center lines are aligned with each other; the first stator tooth portion 21 and the second stator tooth portion 22 are in correspondence with each other and their center lines are aligned with each other; the third piston tooth portion 13 and the fourth piston tooth portion 14 are in correspondence with each other and their center lines are aligned with each other; and the third stator tooth portion 31 and the fourth stator tooth portion 32 are in correspondence with each other and their center lines are aligned with each other. The teeth on the annular piston 10, the first stator 20 and the second stator 30 may be axisymmetric structures, the teeth on the radial outer layer are in the same amount as the teeth on the radial inner layer, and the center lines of the teeth on the radial outer layer are aligned with the center lines of the teeth on the radial inner layer; Such structures are more convenient to process and manufacture. Of course, in other embodiments, the teeth on the outer layer of the annular piston 10, the first stator 20, and the second stator 30 may be staggered from the teeth on the inner layer, provided that the annular piston 10, the first stator 20, and the second stator 30 are engaged via teeth having curved tooth surfaces first, and then engaged via teeth having flat tooth surfaces.

The center lines of the first stator tooth portion 21 and the second stator tooth portion 22 are staggered from the center lines of the third stator tooth portion 31 and the fourth stator tooth portion 32; and the center lines of the first piston tooth portion 11 and the second piston tooth portion 12 are aligned with the center lines of the third piston tooth portion 13 and the fourth piston tooth portion 14. In said structure, when the annular piston 10 is fully engaged with the first stator 20, the center line of the first piston tooth portion 11 is aligned with the tooth root of the first stator tooth portion 21, and the center line of the third piston tooth portion 13 is staggered from the tooth root of the third stator tooth portion 31. Therefore, when the annular piston 10 is disengaged from the first stator 20 and engaged with the second stator 30, the third piston tooth portion 13 and the third stator tooth portion 31 will move securely relative to each other in the circumferential direction. That is, the center line of the third piston tooth portion 13 is prevented from being aligned with the tooth root of the third stator tooth portion 31, thereby preventing a phenomenon that the annular piston 10 and the second stator 30 do not move relatively to each other in the circumferential direction when the annular piston 10 engages with the second stator 30. Such a structural design enables the annular piston 10 to rotate continuously when it reciprocates axially.

In other embodiments, the center lines of the first piston tooth portion 11 and the second piston tooth portion 12 may be staggered from the center lines of the third piston tooth portion 13 and the fourth piston tooth portion 14, and the relative positional relationship between the center lines of the first stator tooth portion 21 and the second stator tooth portion 22 and the center lines of the third stator tooth portion 31 and the fourth stator tooth portion 32 may be adjusted accordingly, to ensure that when the tooth portion at one end of the annular piston 10 is aligned with the corresponding stator tooth root, the tooth portion at the other end of the annular piston 10 is staggered from the corresponding stator tooth root.

Optionally, a distance between the tooth tips of the first piston tooth portion 11 and the second piston tooth portion 12 and the tooth tips of the third piston tooth portion 13 and the fourth piston tooth portion 14 is greater than a distance between the tooth tips of the first stator tooth portion 21 and the second stator tooth portion 22 and the tooth tips of the third stator tooth portion 31 and the fourth stator tooth portion 32, and less than a distance between the tooth tips of the first stator tooth portion 21 and the second stator tooth portion 22 and the tooth roots of the third stator tooth portion 31 and the fourth stator tooth portion 32, and less than a distance between the tooth roots of the first stator tooth portion 21 and the second stator tooth portion 22 and the tooth tips of the third stator tooth portion 31 and the fourth stator tooth portion 32. 31 and the fourth stator tooth portion 32. The distance between the tooth tips of the teeth at the two ends of the annular piston 10 is smaller than the distance between the tooth tips of the two stators, so that, when the tooth portion at one end of the annular piston 10 is about to be disengaged from the corresponding stator tooth portion, the tooth portion at the other end of the annular piston 10 has already begun to engage with the corresponding stator tooth portion, that is, the tooth portion at least one end of the annular piston 10 is kept engaged with the corresponding stator tooth portion, and the engagement enables the annular piston 10 to move circumferentially continuously, so that the annular piston 10 can always move circumferentially, that is, rotate continuously, when moving axially. Furthermore, the distance between the tooth tips at the two ends of the annular piston 10 is smaller than the distance between the tooth tip of any stator and the tooth root of another stator, so that when the annular piston 10 is fully engaged with one of the stators (the tooth tip of the piston tooth portion is engaged with the stator tooth portion at the tooth root), the piston tooth portion at the other end of the annular piston 10 is disengaged from the tooth tip of the other stator tooth portion, so that the annular piston 10 can rotate circumferentially to execute the tooth tip of the other stator.

The method of engaging the first piston tooth portion 11 and the second piston tooth portion 12 with the first stator tooth portion 21 and the second stator tooth portion 22 is shown in Fig. 5. In the initial stage, the first piston tooth portion 11 and the first stator tooth portion 21, which respectively have a curved tooth surface, begin to engage with each other, but the second piston tooth portion 12 and the second stator tooth portion 22 become disengaged with each other. In step 3 in Fig. 5, the second piston tooth portion 12 and the second stator tooth portion 22 begin to engage with each other, while the first piston tooth portion 11 and the first stator tooth portion 21 begin to become disengaged with each other.

It should be noted: for a curved tooth surface, the contour line of the curved tooth surface is a smooth curve, and the included angle between the tangent line of the contour line and the tooth center axis gradually decreases in the direction from the top of the tooth to the tooth root, and the tangent line at each point on the contour line corresponds to the relative motion direction of the tooth when the tooth engages at that point; similarly, for a flat tooth surface, the contour line of the flat tooth surface is a straight line, and the included angle between the straight line and the tooth center line is constant. When the first piston tooth portion 11 and the first stator tooth portion 21 begin to disengage from each other and the second piston tooth portion 12 and the second stator tooth portion 22 begin to engage with each other, the tangent directions of the tooth surfaces at the engagement point between the first piston tooth portion 11 and the first stator tooth portion 21 are the same as the tangent directions of the tooth surfaces of the first piston tooth portion 11 and the first stator tooth portion 21 (actually the directions of the contour lines of the tooth surfaces), thereby achieving a smooth transition. The same is true for the engagement structures between the third piston tooth portion 13, the fourth piston tooth portion 14, the third start tooth portion 31 and the fourth stator tooth portion 32 at the other end of the annular piston 10, which will not be further detailed here.

The rotary drive mechanism comprises two axially arranged sets of first stators 20, second stators 30 and annular pistons 10, the first stators 20 and the second stators 30 in the two sets are fixed relative to each other, and the two annular pistons 10 in the two sets are fixed relative to each other circumferentially and are movable relative to each other axially. As shown in Fig. 1 and 2, two sets of first stators 20, second stators 30 and annular pistons 10 are arranged in the axial direction. In particular, the second stator 30 in one set and the first stator 20 in the other set are connected to each other and can be integrally formed. The functions of the two sets of structures are essentially the same; therefore, the overall reliability can be improved. When one set is damaged, the other set can be used.

In particular, the center lines of the first piston tooth portions 11 of the two annular pistons 10 are staggered relative to each other. When the rotary drive mechanism is stopped, an annular piston 10 can be moved so as to be completely engaged with a stator to realize self-locking, that is, the annular piston 10 will not rotate because an external torque now acts on the annular piston 10. In other words, when the rotary drive mechanism is not driven, if the piston tooth portion at one end of the first annular piston 10 is completely engaged with the stator tooth portion, the annular piston 10 can only rotate in one direction due to the engagement of the piston tooth portion at the other end with the stator tooth portion when the annular piston 10 moves axially; At the same time, the second annular piston 10 is in an incompletely engaged state, and the annular portion 10 will rotate in a reverse direction when the annular piston 10 is driven to move reversely in the axial direction, that is, the rotation direction can be determined by selecting the movement direction of the annular piston 10 in the axial direction; furthermore, the second annular piston 10 can drive the first annular piston 10 to rotate, therefore, continuous rotation can be realized by means of the axial movement of the two annular pistons.

See Fig. 6 and 7, which are planar development views of the tooth portions, where sequence numbers represent sequential steps. When the two annular pistons 10 (hereinafter, distinguished as a left annular piston 10 and a right annular piston 10) are in the same initial position, the left annular piston 10 is in a self-locking position, and the teeth at the two ends of the right annular piston 10 are partially engaged with the corresponding stator tooth portion. In Fig. 6, the left annular piston 10 and the right annular piston 10 are simultaneously driven to move to the right, and the right annular piston 10 rotates "upward" under the guidance of the second stator 30, so that the left annular piston 10 can also be driven to rotate "upward", and then the two annular pistons 10 are additionally driven to reciprocate axially, thereby realizing continuous "upward" rotation; In Fig. 7, the right annular piston 10 is driven to move axially to the left, and the left annular piston 10 is driven to move axially to the right, and the right annular piston 10 rotates "downward" under the guidance of the first stator 20, so that the left annular piston 10 can also be driven to rotate "downward", and then the two annular pistons 10 are further driven to reciprocate axially, thereby realizing continuous "downward" rotation.

The rotary drive mechanism comprises an inner ring 40, the two annular pistons 10 are axially slidably mounted on the inner ring 40, and the two annular pistons 10 are circumferentially fixed with respect to the inner ring 40. The annular piston 10 can be mounted on the inner ring 40 through the fit between a spline and a spline groove, whereby it can be axially moved with respect to the inner ring 40, but cannot rotate circumferentially. The movement direction of the inner ring 40 is limited by means of relatively fixed structures, that is, the inner ring 40 can only rotate with respect to the stators, but cannot move axially with respect to the stators. For example, the structure for guiding the inner ring 40 can be provided in a plurality of stators. As shown in Fig. 2, the inner ring 40 passes through the stators and the annular pistons, and the other end of the inner ring 40 may be provided with an end cap 50, which can limit the axial movement of the inner ring 40 and achieve sealing. The end cap 50 may be annular, and the integral rotary drive mechanism is provided with a central hole for pipes to pass through.

In the structure where the first stator 20 and the second stator 30 are integrally connected, a cavity may be provided to accommodate the movement of the two annular pistons 10, and the annular pistons 10 may be driven to move axially by supplying hydraulic power in the cavity.

Furthermore, the present disclosure also provides a boom, which is provided with the rotary drive mechanism described in the previous solution. The stator portions may be relatively fixed to a boom section of the boom, and the annular piston 10, especially the inner ring 40, may be coupled with another adjacent boom section to drive the adjacent boom section such that it rotates.

Furthermore, the present description also provides engineering machinery, which is provided with the boom described in the previous solution. The engineering machinery may be a concrete pumping truck, a crane or the like.

While some preferred embodiments of the present disclosure are described above in detail with reference to the accompanying drawings, the present disclosure is not limited to those embodiments. Various simple variations to the technical solution of the present disclosure may be made, including combinations of the specific technical features in any appropriate manner, within the scope of the technical ideal of the present disclosure. In order to avoid unnecessary repetitions, various possible combinations are not specifically described in the present disclosure. However, such variations and simple combinations shall also be considered to be described herein and included within the scope of protection of the present disclosure.

Claims (13)

1. A rotary drive mechanism, comprising an annular piston (10) and a stator, wherein the annular piston (10) is provided with a piston tooth portion having a protruding curved tooth surface and a piston tooth portion having an inclined flat tooth surface; the stator is provided with a stator tooth portion having a protruding curved tooth surface and a stator tooth portion having an inclined flat tooth surface; The annular piston (10) is actuatable to move axially relative to the stator, and the annular piston (10) engages with the stator tooth portion having the protruding curved tooth surface through the piston tooth portion having the protruding curved tooth surface first and then engages with the stator tooth portion having the inclined flat tooth surface through the piston tooth portion having the inclined flat tooth surface, so that the annular piston (10) is driven to rotate circumferentially. 2. The rotary drive mechanism according to claim 1, wherein the stator comprises a first annular stator (20) and a second annular stator (30), and the annular piston (10) is disposed between the first stator (20) and the second stator (30). 3. The rotary drive mechanism according to claim 2, wherein a first axial end of the annular piston (10) is provided with a first piston tooth portion (11) and a second piston tooth portion (12), and a second axial end of the annular piston (10) is provided with a third piston tooth portion (13) and a fourth piston tooth portion (14); the first stator (20) is provided with a first stator tooth portion (21) capable of engaging with the first piston tooth portion (11) and a second stator tooth portion (22) capable of engaging with the second piston tooth portion (12); the second stator (30) is provided with a third stator tooth portion (31) capable of engaging with the third piston tooth portion (13) and a fourth stator tooth portion (32) capable of engaging with the fourth piston tooth portion (14); The first piston tooth portion (11) and the first stator tooth portion (21) have a protruding curved tooth surface respectively; the second piston tooth portion (12) and the second stator tooth portion (22) have an inclined flat tooth surface, respectively; the third piston tooth portion (13) and the third stator tooth portion (31) have a protruding curved tooth surface, respectively; and the fourth piston tooth portion (14) and the fourth stator tooth portion (32) have an inclined flat tooth surface, respectively, where the annular piston (10) can be driven to reciprocate axially, where the first piston tooth portion (11) first engages with the first stator tooth portion (21) and then the second piston tooth portion (12) engages with the second stator tooth portion (22); The third portion of the piston tooth (13) first engages with the third portion of the stator tooth (31), and then the fourth portion of the piston tooth (14) engages with the fourth portion of the stator tooth (32), so that the annular piston (10) is urged to rotate. 4. The rotary drive mechanism according to claim 3, wherein the first piston tooth portion (11), the first stator tooth portion (21), the third piston tooth portion (13) and the third stator tooth portion (31) have an involute tooth surface, respectively. 5. The rotary drive mechanism according to claim 3, wherein the first piston tooth portion (11) and the second piston tooth portion (12) are located on an inner side and an outer side radially, respectively, and the third piston tooth portion (13) and the fourth piston tooth portion (14) are located on the inner side and the outer side radially, respectively. 6. The rotary drive mechanism according to claim 5, wherein the first piston tooth portion (11) and the second piston tooth portion (12) are in one-to-one correspondence and their center lines are aligned with each other; the first stator tooth portion (21) and the second stator tooth portion (22) are in one-to-one correspondence and their center lines are aligned with each other; the third piston tooth portion (13) and the fourth piston tooth portion (14) are in one-to-one correspondence and their center lines are aligned with each other; and the third stator tooth portion (31) and the fourth stator tooth portion (32) are in one-to-one correspondence and their center lines are aligned with each other. 7. The rotary drive mechanism according to claim 6, wherein the center lines of the first stator tooth portion (21) and the second stator tooth portion (22) are staggered from the center lines of the third stator tooth portion (31) and the fourth stator tooth portion (32); and the center lines of the first piston tooth portion (11) and the second piston tooth portion (12) are aligned with the center lines of the third piston tooth portion (13) and the fourth piston tooth portion (14). 8. The rotary drive mechanism according to claim 7, wherein a distance between the tips of the teeth of the first piston tooth portion (11) and the second piston tooth portion (12) and the tips of the teeth of the third piston tooth portion (13) and the fourth piston tooth portion (14) is greater than a distance between the tips of the teeth of the first stator tooth portion (21) and the second stator tooth portion (22) and the tips of the teeth of the third stator tooth portion (31) and the fourth stator tooth portion (32), and less than a distance between the tips of the teeth of the first stator tooth portion (21) and the second stator tooth portion (22) and the roots of the teeth of the third stator tooth portion (31) and the fourth stator tooth portion (32), and less than a distance between the roots of the teeth of the first stator tooth portion (21) and the second stator tooth portion (22). (21) and the second stator tooth portion (22) and the tooth tips of the third stator tooth portion (31) and the fourth stator tooth portion (32). 9. The rotary drive mechanism according to claim 8, wherein the rotary drive mechanism comprises two axially arranged sets of first stators (20), second stators (30) and annular pistons (10), the first stators (20) and the second stators (30) in the two sets are fixed relative to each other, and the two annular pistons (10) in the two sets are fixed relative to each other circumferentially and are axially movable relative to each other. 10. The rotary drive mechanism according to claim 9, wherein the center lines of the first piston tooth portions (11) of the two annular pistons (10) are staggered relative to each other. 11. The rotary drive mechanism according to claim 9, wherein the rotary drive mechanism comprises an inner ring (40), the two annular pistons (10) are axially slidably mounted on the inner ring (40), and the two annular pistons (10) are circumferentially fixed with respect to the inner ring (40). 12. A pen provided with the rotary drive mechanism according to any of claims 1-11. 13. An engineering machinery provided with the boom according to claim 12.