Rotary drive mechanism, boom and technical machine

Abstract

A rotary drive mechanism, a boom, and a technical machine are described. The rotary drive mechanism comprises an annular piston (10) and a stator (20, 30); the annular piston (10) is provided with a piston tooth section (11, 13) having a projecting curved tooth surface and a piston tooth section (12, 14) having an inclined flat tooth surface; the stator (20, 30) is provided with a stator tooth section (21, 31) having a projecting curved tooth surface and a stator tooth section (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 the engagement of the curved tooth surface and the engagement of the flat tooth surface can ensure a uniform transmission in an initial engagement phase, so that the noise is lower, and the axial movement can be converted into a uniform rotation in a subsequent engagement phase, thus providing a more stable torque output.

Description

CROSS-REFERENCE TO A RELATED APPLICATION

[0001] This application claims the benefit of Chinese Patent Application No. 202210259497.3, filed on March 16, 2022, the contents of which are incorporated herein by reference. TECHNICAL BACKGROUND

[0002] The present disclosure relates to the field of booms, in particular to a rotary drive mechanism, a boom and a technical machine. BACKGROUND

[0003] A boom typically comprises several interconnected articulated boom sections and is extended and collapsed by driving the oil cylinders of each boom section. The relative angle of rotation between any two adjacent boom sections is a key factor influencing the flexibility and working range of the boom. The greater the relative angle of rotation between any two adjacent boom sections, the greater the flexibility and working range of the boom, and vice versa.

[0004] Currently, for most boom systems, the maximum relative rotation angle between two adjacent boom sections is no more than 220°, which sometimes makes it difficult to meet material distribution requirements in complex construction environments; especially when the boom system is to be guided around obstacles, the limited relative rotation angle makes it difficult to unfold the boom system to a desired position.In addition, due to the connections of the boom sections formed by hinges between oil cylinders and curved plates, the movement pattern of the boom is very simple when it is unfolded, in particular, the boom sections can only be unfolded clockwise or counterclockwise; moreover, if the relative rotation angle of the boom sections is very large to fold the boom sections, the boom sections can be rotated in the opposite direction by a very large angle, which greatly affects the flexibility and working efficiency of the boom.

[0005] In addition, the relative angular velocity between the boom sections is not proportional to the stroke of the oil cylinder. The relative angular velocity between the boom sections varies with the varying relative angle of rotation. Furthermore, because the boom sections are very long, a "reinforcing effect" occurs at the ends, and such fluctuations significantly reduce the stability and accuracy of the boom ends. SUMMARY

[0006] An object of the present disclosure is to provide a rotary drive mechanism that solves the problems of uneven torque output and unstable rotation speed.

[0007] To achieve the above object, the present disclosure provides, in one aspect, 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 can be driven to move axially with respect to the stator, wherein the annular piston first engages with the stator tooth portion having the projecting curved tooth surface via the piston tooth portion having the projecting curved tooth surface and then engages with the stator tooth portion having the inclined flat tooth surface via the piston tooth portion having the inclined flat tooth surface, so that the annular piston is driven to rotate in the circumferential direction;

[0008] Optionally, the stator comprises an annular first stator and an annular second stator, and the annular piston is arranged between the first stator and the second stator.

[0009] 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 engageable with the first piston tooth portion and a second stator tooth portion engageable with the second piston tooth portion; the second stator is provided with a third stator tooth portion engageable with the third piston tooth portion and a fourth stator tooth portion engageable with the fourth piston tooth portion; the first piston tooth portion and the first stator tooth portion each have a projecting curved tooth surface;the second piston tooth portion and the second stator tooth portion each have an inclined flat tooth surface; the third piston tooth portion and the third stator tooth portion each have a projecting curved tooth surface; and the fourth piston tooth portion and the fourth stator tooth portion each have an inclined flat tooth surface; wherein the annular piston is driveable to reciprocate axially, wherein the first piston tooth portion is first engaged with the first stator tooth portion and then the second piston tooth portion is engaged with the second stator tooth portion; the third piston tooth portion is first engaged with the third stator tooth portion and then the fourth piston tooth portion is engaged with the fourth stator tooth portion, such that the annular piston is urged to rotate.

[0010] Optionally, the first piston tooth section, the first stator tooth section, the third piston tooth section and the third stator tooth section each have an involute tooth surface.

[0011] Optionally, the first piston tooth portion and the second piston tooth portion are arranged radially on an inner side and an outer side, respectively, and the third piston tooth portion and the fourth piston tooth portion are arranged radially on the inner side and the outer side, respectively.

[0012] Optionally, the first piston tooth portion and the second piston tooth portion are in one-to-one correspondence and their centerlines are aligned with each other; the first stator tooth portion and the second stator tooth portion are in one-to-one correspondence and their centerlines are aligned with each other; the third piston tooth portion and the fourth piston tooth portion are in one-to-one correspondence and their centerlines are aligned with each other; and the third stator tooth portion and the fourth stator tooth portion are in one-to-one correspondence and their centerlines are aligned with each other.

[0013] Optionally, the centerlines of the first stator tooth portion and the second stator tooth portion are offset from the centerlines of the third stator tooth portion and the fourth stator tooth portion; and the centerlines of the first piston tooth portion and the second piston tooth portion are aligned with the centerlines of the third piston tooth portion and the fourth piston tooth portion.

[0014] Optionally, a distance between the tooth tips of the first piston tooth section and the second piston tooth section and the tooth tips of the third piston tooth section and the fourth piston tooth section is greater than a distance between the tooth tips of the first stator tooth section and the second stator tooth section and the tooth tips of the third stator tooth section and the fourth stator tooth section, and smaller than a distance between the tooth tips of the first stator tooth section and the second stator tooth section and the tooth bases of the third stator tooth section and the fourth stator tooth section, and smaller than a distance between the tooth bases of the first stator tooth section and the second stator tooth section and the tooth tips of the third stator tooth section and the fourth stator tooth section.

[0015] Optionally, the rotary drive mechanism comprises two axially arranged sets of first stators, second stators and annular pistons, wherein the first stators and the second stators in the two sets are fixed with respect to each other and the two annular pistons in the two sets are fixed with respect to each other in the circumferential direction and movable with respect to each other in the axial direction.

[0016] Optionally, the center lines of the first piston tooth sections of the two ring pistons are offset from each other.

[0017] Optionally, the rotary drive mechanism comprises an inner ring, the two annular pistons are mounted axially displaceably on the inner ring, and the two annular pistons are fixed in the circumferential direction with respect to the inner ring.

[0018] Furthermore, the present disclosure provides a boom equipped with the rotary drive mechanism described in the above solution.

[0019] Furthermore, the present disclosure also provides a technical machine equipped with the boom described in the above solution.

[0020] With the above technical solution, the combination of the engagement of the curved tooth surface and the engagement of the flat tooth surface can ensure smooth transmission in an initial engagement phase, so that the noise is lower and the axial movement can be converted into smooth rotation in a subsequent engagement phase, thereby achieving more stable torque output. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a partial schematic view of the rotary drive mechanism according to an embodiment of the present disclosure; Fig. 2 is an exploded view of the rotary drive mechanism according to the present embodiment of the disclosure; Fig. 3 is a perspective view of the annular piston according to the present embodiment of the disclosure; Fig. 4 is a schematic structural view of the engagement between the annular piston and the stator according to the present embodiment of the disclosure; Fig. 5 is a flowchart of the engagement between the tooth portions of the annular piston and the tooth portions of the stator according to the embodiment of the present disclosure; and Fig. 6 and Fig. 7 are flow diagrams of the rotation of the annular piston with respect to the stator in two different directions. Reference symbol

[0021] 10 - annular piston, 11 - first piston tooth section, 12 - second piston tooth section, 13 - third piston tooth section, 14 - fourth piston tooth section, 20 - first stator, 21 - first stator tooth section, 22 - second stator tooth section, 30 - second stator, 31 - third stator tooth section, 32 - fourth stator tooth section, 40 - inner ring, 50 - end cap. DETAILED DESCRIPTION

[0022] Some embodiments of the present disclosure are explained in more detail below with reference to the accompanying drawings. It should be understood that the embodiments described herein are for the purpose of describing and explaining the present disclosure only, but are not intended to limit the present disclosure.

[0023] 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 can be driven to move axially with respect to the stator, wherein the annular piston 10 is first engaged with the stator tooth portion having the protruding curved tooth surface via the piston tooth portion having the protruding curved tooth surface and then engaged with the stator tooth portion having the inclined flat tooth surface via the piston tooth portion having the inclined flat tooth surface, so that the annular piston 10 is driven to rotate in the circumferential direction.;

[0024] In the two tooth sections of the annular piston 10, the tooth surface of one tooth section is a curved tooth surface and has a protruding shape, while the tooth surface of the other tooth section is a flat tooth surface. Accordingly, the tooth surface of one tooth section of the stator is a curved tooth surface and protrudes outward, while the tooth surface of the other tooth section of the stator is a flat tooth surface. The curved tooth surface of the annular piston 10 engages with the curved tooth surface of the stator, and the flat tooth surface of the annular piston 10 engages with the flat tooth surface of the stator.

[0025] The tooth surfaces refer to the surfaces that mesh when two tooth sections mesh. 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.

[0026] Specifically, the annular piston 10 may be driven to move axially, e.g., by hydraulic pressure or air pressure, etc., so that the tooth portions at both ends of the annular piston 10 are engaged and disengaged from the tooth portions of the stator. During the engagement process of two teeth, the tip of the stator tooth is slightly offset from the tip of the annular piston 10, and the tooth on the stator may guide the tooth on the annular piston 10 to move relatively circumferentially, so that the tip of the annular piston 10 moves to align with the base of the stator tooth, thereby rotating the annular piston 10 with respect to the stator.

[0027] As in Fig. 5, when the annular piston 10 is engaged with the stator (e.g., the first stator 20), it is first engaged with the first stator 20 through the tooth engagement between the curved tooth surfaces, which are the existing tooth structures. Such a structure is helpful for reducing wear between the tooth portions and realizing stable transmission, and realizing advantages such as work relief, durability, and low noise, etc. Of course, even if the axial relative movement of the two components is uniform, the relative movement in the circumferential direction caused by the engagement is uneven. Then, the second piston tooth portion 12 is engaged with the second stator tooth portion 22.The two teeth are irregular structures that differ from existing teeth. This means that the tooth surface of each tooth is flat and forms an angle with respect to the axial direction (or the centerline of the tooth). When the axial relative movement is uniform, the circumferential movement of the annular piston 10 with respect to the first stator 20 is also uniform, i.e., uniform rotation is realized.

[0028] The stator includes an annular first stator 20 and an annular second stator 30, and the annular piston 10 is disposed between the first stator 20 and the second stator 30. The annular piston 10 can move axially between the first stator 20 and the second stator 30, and the annular piston 10 is driven to rotate in the circumferential direction by the engagement between the tooth portions, thereby realizing continuous rotation.

[0029] 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 each have a projecting curved tooth surface;the second piston tooth portion 12 and the second stator tooth portion 22 each have an inclined flat tooth surface; the third piston tooth portion 13 and the third stator tooth portion 31 each have a projecting curved tooth surface; and the fourth piston tooth portion 14 and the fourth stator tooth portion 32 each have an inclined flat tooth surface; wherein the annular piston 10 can be driven to reciprocate axially, wherein the first piston tooth portion 11 is first engaged with the first stator tooth portion 21 and then the second piston tooth portion 12 is engaged with the second stator tooth portion 22; the third piston tooth portion 13 is first engaged with the third stator tooth portion 31 and then the fourth piston tooth portion 14 is engaged with the fourth stator tooth portion 32, so that the annular piston 10 is rotated.

[0030] The annular piston 10, the first stator 20, and the second stator 30 can be substantially tubular and are arranged coaxially. The rotation of the annular piston 10 is a rotation about its central axis.

[0031] As in Fig. 5, when the annular piston 10 is engaged with the first stator 20, the first piston tooth portion 11 is first engaged with the first stator tooth portion 21, that is, the annular piston 10 is first engaged with the first stator 20 by means of the tooth engagement between the curved tooth surfaces, which are existing tooth structures. Such a structure is helpful for reducing wear between the tooth portions and realizing stable transmission, and has advantages such as workability, durability, and quietness, etc. Of course, even if the axial relative movement of the two components is uniform, the relative movement in the circumferential direction caused by the engagement is uneven. Then, the second piston tooth portion 12 is engaged with the second stator tooth portion 22.The two teeth are irregular structures that differ from existing teeth. This means that the tooth surface of each tooth is flat and forms an angle with respect to the axial direction (or the centerline of the tooth). When the axial relative movement is uniform, the circumferential movement of the annular piston 10 with respect to the first stator 20 is also uniform, meaning that uniform rotation is realized.

[0032] It should be noted that in the phase where the first piston tooth portion 11 is engaged with the first stator tooth portion 21, the second piston tooth portion 12 is not engaged with the second stator tooth portion 22; and when the second piston tooth portion 12 starts to engage with the second stator tooth portion 22, the first piston tooth portion 11 starts to disengage from the first stator tooth portion 21.

[0033] 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 substantially the same as the engagement of the annular piston 10 with the first stator as described above and will not be further described here.

[0034] 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 each have an involute tooth surface. In other words, the curved tooth surface is an involute tooth surface, i.e., the tooth surface structure of the teeth in existing gears.

[0035] The first piston tooth portion 11 and the second piston tooth portion 12 are located radially on an inner side and an outer side, respectively, and the third piston tooth portion 13 and the fourth piston tooth portion 14 are located radially on the inner side and the outer side, respectively. As shown in the Fig. As shown in Figures 1-4, the axial ends of the annular piston 10 are each provided with a toothed portion, and the toothed portion comprises an inner layer and an outer layer at each end. Accordingly, the two stators intended to engage with the annular piston 10 are each provided with a toothed portion comprising an inner layer and an outer layer. It should be noted that either the toothed portion with a curved tooth surface or the toothed portion with a flat tooth surface can be arranged on the outer layer or the inner layer.

[0036] The first piston tooth portion 11 and the second piston tooth portion 12 correspond one-to-one and their center lines are aligned with each other; the first stator tooth portion 21 and the second stator tooth portion 22 correspond one-to-one and their center lines are aligned with each other; the third piston tooth portion 13 and the fourth piston tooth portion 14 correspond one-to-one and their center lines are aligned with each other; and the third stator tooth portion 31 and the fourth stator tooth portion 32 correspond one-to-one 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 can be axisymmetric structures, the teeth on the radially outer layer are the same number as the teeth on the radially inner layer, and the centerlines of the teeth on the radially outer layer are aligned with the centerlines of the teeth on the radially inner layer; such structures are easier 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 can be offset from the teeth on the inner layer, as long as the annular piston 10, the first stator 20, and the second stator 30 are first engaged via the teeth with curved tooth surfaces and then via the teeth with flat tooth surfaces.

[0037] The centerlines of the first stator tooth portion 21 and the second stator tooth portion 22 are offset from the centerlines of the third stator tooth portion 31 and the fourth stator tooth portion 32; and the centerlines of the first piston tooth portion 11 and the second piston tooth portion 12 are aligned with the centerlines of the third piston tooth portion 13 and the fourth piston tooth portion 14. With such a structure, when the annular piston 10 is fully engaged with the first stator 20, the centerline of the first piston tooth portion 11 is aligned with the tooth base of the first stator tooth portion 21, and the centerline of the third piston tooth portion 13 is offset from the tooth base 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 are guaranteed to move relative to each other in the circumferential direction. That is, the center line of the third piston tooth portion 13 is prevented from aligning with the tooth base of the third stator tooth portion 31, thus preventing the phenomenon that the annular piston 10 and the second stator 30 do not move relative to each other in the circumferential direction when the annular piston 10 is engaged with the second stator 30. Such a structure allows the annular piston 10 to rotate continuously while reciprocating axially.

[0038] In other embodiments, the centerlines of the first piston tooth portion 11 and the second piston tooth portion 12 may be offset from the centerlines of the third piston tooth portion 13 and the fourth piston tooth portion 14, and the relative positional relationship between the centerlines of the first stator tooth portion 21 and the second stator tooth portion 22 and the centerlines 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 tooth base of the corresponding stator, the tooth portion at the other end of the annular piston 10 is offset from the tooth base of the corresponding stator.

[0039] Optionally, a distance between the tooth tips of the first piston tooth section 11 and the second piston tooth section 12 and the tooth tips of the third piston tooth section 13 and the fourth piston tooth section 14 is greater than a distance between the tooth tips of the first stator tooth section 21 and the second stator tooth section 22 and the tooth tips of the third stator tooth section 31 and the fourth stator tooth section 32, and smaller than a distance between the tooth tips of the first stator tooth section 21 and the second stator tooth section 22 and the tooth bases of the third stator tooth section 31 and the fourth stator tooth section 32, and smaller than a distance between the tooth bases of the first stator tooth section 21 and the second stator tooth section 22 and the tooth tips of the third stator tooth section 31 and the fourth stator tooth section 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 detach from the tooth portion of the corresponding stator, the tooth portion at the other end of the annular piston 10 has already begun to engage with the tooth portion of the corresponding stator, which means that the tooth portion at at least one end of the annular piston 10 is held in engagement with the tooth portion of the corresponding stator, and the engagement allows the annular piston 10 to move continuously in the circumferential direction, so that the annular piston 10 can always move in the circumferential direction, ie, can rotate continuously when it moves axially.In addition, 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 base 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 base), 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 is able to rotate circumferentially to move the tooth tip of the other stator.

[0040] The process of engagement of 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 phase, the first piston tooth portion 11 and the first stator tooth portion 21, each having a curved tooth surface, begin to mesh with each other, but the second piston tooth portion 12 and the second stator tooth portion 22 are not meshed with each other. In step 3 in Fig. 5, the second piston tooth section 12 and the second stator tooth section 22 begin to mesh with each other, while the first piston tooth section 11 and the first stator tooth section 21 begin to separate from each other.

[0041] It should be noted that for a curved tooth surface, the contour line of the curved tooth surface is a smooth curve, and the included angle between the tangent of the contour line and the tooth center line gradually decreases in the direction from the tooth tip to the tooth base, and the tangent at any point on the contour line corresponds to the relative movement direction of the tooth when the tooth is in mesh 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 separate from each other, and the second piston tooth portion 12 and the second stator tooth portion 22 begin to mesh with each other, the tangent directions of the tooth surfaces at the meshing 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), thus achieving a smooth transition. The same applies to the meshing structures between the third piston tooth portion 13, the fourth piston tooth portion 14, the third starting tooth portion 31, and the fourth stator tooth portion 32 at the other end of the annular piston 10, which will not be discussed further here.

[0042] The rotary drive mechanism comprises two axially arranged sets of first stators 20, second stators 30 and annular pistons 10, wherein 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 in the circumferential direction and movable relative to each other in the axial direction. As shown in the Fig. 1 and Fig. As shown in Figure 2, two sets of first stators 20, second stators 30, and annular piston 10 are arranged in the axial direction. Specifically, the second stator 30 in one group and the first stator 20 in the other group are connected to each other and may be integrally formed. The functions of the two sets of structures are essentially the same; therefore, overall reliability can be improved. If one set is damaged, the other set can be used.

[0043] Specifically, the center lines of the first piston tooth portions 11 of the two annular pistons 10 are offset from each other. When the rotary drive mechanism is stopped, one annular piston 10 can be moved so that it fully engages with a stator to realize self-locking, i.e., the annular piston 10 will not rotate because an external torque now acts on the annular piston 10. In other words, if the rotary drive mechanism is not actuated when the piston tooth portion at one end of the first annular piston 10 is fully engaged with the stator tooth portion, the annular piston 10 can only rotate in one direction when the annular piston 10 is moved axially due to the engagement of the piston tooth portion at the other end with the stator tooth portion;At the same time, the second annular piston 10 is in an incomplete engagement state, and the annular portion 10 will rotate in a reverse direction when the annular piston 10 is driven to move backward in the axial direction. This means that the rotation direction can be determined by selecting the movement direction of the annular piston 10 in the axial direction. In addition, the second annular piston 10 can drive the first annular piston 10 to rotate, thereby realizing continuous rotation by means of the axial movement of the two annular pistons.

[0044] See Fig. 6 and Fig. 7, which are planar development views of the tooth sections, in which the consecutive numbers represent successive steps. When the two annular pistons 10 (hereinafter referred to as the left annular piston 10 and the 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 both ends of the right annular piston 10 are partially engaged with the corresponding stator tooth section. Fig. 6, the left annular piston 10 and the right annular piston 10 are driven simultaneously 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 further driven to move axially back and forth, so that a continuous "upward" rotation is realized; 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 move back and forth axially, thereby realizing a continuous "downward" rotation.

[0045] The rotary drive mechanism includes an inner ring 40. The two annular pistons 10 are mounted axially displaceably on the inner ring 40, and the two annular pistons 10 are fixed circumferentially with respect to the inner ring 40. The annular piston 10 can be mounted on the inner ring 40 by the fit between a key and a keyway, so that it can move axially with respect to the inner ring 40, but cannot rotate in the circumferential direction. The direction of movement of the inner ring 40 is limited by relatively fixed structures, i.e., the inner ring 40 can only rotate with respect to the stators, but cannot move axially with respect to the stators. For example, structures for guiding the inner ring 40 can be provided on a variety of stators. As shown in Fig.As shown in Figure 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 that can limit the axial movement of the inner ring 40 and achieve sealing. The end cap 50 may be annular, and the integrated rotary drive mechanism is provided with a central hole through which piping can pass.

[0046] In the structure in which the first stator 20 and the second stator 30 are integrally connected, a cavity may be provided for receiving the movement of the two annular pistons 10, and the annular pistons 10 may be axially driven by supplying hydraulic power in the cavity.

[0047] Furthermore, the present disclosure provides a boom equipped with the rotary drive mechanism described in the above solution. The stator sections can be relatively fixedly connected to one boom section of the boom, and the annular piston 10, in particular the inner ring 40, can be engaged with another adjacent boom section to rotate the adjacent boom section.

[0048] Furthermore, the present disclosure also provides technical machines equipped with the boom described in the above solution. The technical machines may be a concrete pump truck, a crane, or the like.

[0049] Although some preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, the present disclosure is not limited to these embodiments. Within the scope of the technical ideal of the present disclosure, various simple variations of the technical solution of the present disclosure can be made, including combinations of the specific technical features in any suitable form. To avoid unnecessary repetition, various possible combinations are not explicitly described in the present disclosure. However, it is understood that such simple variations and combinations are also disclosed herein and fall within the scope of the present disclosure. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] CN 202210259497.3

[0001]

Claims

[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 projecting 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 projecting curved tooth surface and a stator tooth portion having an inclined flat tooth surface; the annular piston (10) can be driven to move axially with respect to the stator, and the annular piston (10) is first engaged with the stator tooth portion having the projecting curved tooth surface via the piston tooth portion having the projecting curved tooth surface and then with the stator tooth portion having the inclined flat tooth surface via the piston tooth portion having the inclined flat tooth surface, so that the annular piston (10) is driven to rotate in the circumferential direction. [2] A rotary drive mechanism according to claim 1, wherein the stator comprises an annular first stator (20) and an annular second stator (30), and the annular piston (10) is arranged between the first stator (20) and the second stator (30). [3] A 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) 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) each have a projecting curved tooth surface; the second piston tooth portion (12) and the second stator tooth portion (22) each include an inclined flat tooth surface; the third piston tooth portion (13) and the third stator tooth portion (31) each include a projecting curved tooth surface; and the fourth piston tooth portion (14) and the fourth stator tooth portion (32) each include an inclined flat tooth surface, wherein the annular piston (10) can be driven to reciprocate axially, wherein the first piston tooth portion (11) is first engaged with the first stator tooth portion (21) and then the second piston tooth portion (12) is engaged with the second stator tooth portion (22);the third piston tooth portion (13) is first engaged with the third stator tooth portion (31) and then the fourth piston tooth portion (14) is engaged with the fourth stator tooth portion (32) so that the annular piston (10) is pressed to rotate; [4] A 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) each have an involute tooth surface. [5] A rotary drive mechanism according to claim 3, wherein the first piston tooth portion (11) and the second piston tooth portion (12) are radially arranged on an inner side and an outer side, respectively, and the third piston tooth portion (13) and the fourth piston tooth portion (14) are radially arranged on the inner side and the outer side, respectively. [6] A 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] A 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 offset 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 tooth tips of the first piston tooth portion (11) and the second piston tooth portion (12) and tooth tips of the third piston tooth portion (13) and the fourth piston tooth portion (14) is greater than a distance between tooth tips of the first stator tooth portion (21) and the second stator tooth portion (22) and tooth tips of the third stator tooth portion (31) and the fourth stator tooth portion (32), and smaller than a distance between the tooth tips of the first stator tooth portion (21) and the second stator tooth portion (22) and the tooth bases of the third stator tooth portion (31) and the fourth stator tooth portion (32), and smaller than a distance between the tooth bases 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). [9] A 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), wherein the first stators (20) and the second stators (30) in the two sets are fixed with respect to each other and the two annular pistons (10) in the two sets are fixed with respect to each other in the circumferential direction and are axially movable with respect to each other. [10] 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 offset from each other. [11] Rotary drive mechanism according to claim 9, wherein the rotary drive mechanism comprises an inner ring (40), the two annular pistons (10) are mounted axially displaceably on the inner ring (40), and the two annular pistons (10) are fixed in the circumferential direction with respect to the inner ring (40). [12] Boom with a rotary drive mechanism according to any one of claims 1-11. [13] A technical machine with a boom according to claim 12.

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