CN115807819A - A composite slider type constant velocity universal joint and universal joint transmission device - Google Patents

Abstract

The invention relates to the technical field of constant velocity universal joints, in particular to a composite slider type constant velocity universal joint and a universal joint transmission device. The composite slider type constant velocity universal joint includes a spline-like shaft, an axial limiter The end cover assembly, the composite slider assembly and the housing, a plurality of spline-like protrusions are arranged around the outer peripheral surface of the spline-like shaft, and a plurality of spline-like protrusions are arranged around the inner peripheral surface of the housing. The spline-like groove is compatible with the composite slider assembly, the spline-like shaft is connected to the housing through the composite slider assembly, and the axial limit end cover assembly is sealed to seal the annular gap between the spline-like shaft and the housing within the gap. The driving shaft transmits power to the housing through the composite slider assembly through any type of coupling structure; the composite slider assembly slides in the spline-like protrusion of the spline-like shaft and the spline-like groove of the housing, and passes through The spherical pair of the block assembly realizes the movement of the spherical lower pair to adapt to the change of the angle between the shafts, and realizes the multi-point load equal-speed transmission of the torque from the spline-like shaft to the housing.

Description

A composite slider type constant velocity universal joint and universal joint transmission device

technical field

The invention relates to the technical field of constant velocity universal joints, in particular to a composite slider type constant velocity universal joint and a universal joint transmission device.

Background technique

The universal joint is the universal joint, which is a machine that realizes variable-angle power transmission. It is used for the position where the direction of the transmission axis needs to be changed. It is the "joint" part of the universal transmission device. The constant velocity universal joint is a device that connects two shafts with an angle between the shafts or changes in mutual position, and makes the two shafts transmit power at the same angular velocity. speed problem.

In the prior art, the universal joint transmission device includes a universal joint and a driving shaft and a driven shaft respectively fixedly connected to the universal joint. During operation, power is transmitted from the driving shaft to the universal joint, and then transmitted by the universal joint. To the driven shaft, in the process of power transmission, the universal joint adapts to the change of the angle between the shafts and the relative position between the driving shaft and the driven shaft, so as to realize the transmission of power between the driving shaft and the driven shaft. Universal joints include cross-axis universal joints, tripod-type universal joints, ball-fork universal joints, ball-cage universal joints, etc. At present, the traditional variable-angle power transmission mechanism has its own scope of application. For example, the cross-shaft universal joint is suitable for medium and low speeds and high torque, but it is large in size, non-constant speed transmission, and difficult to seal the joint; the ball-joint universal joint is suitable for high-power Transmission, and constant speed transmission can be achieved, but under high torque, the ball joint will self-lock and cause damage. The above-mentioned variable-angle power transmission mechanism has problems such as poor use effect and unsuitability for applications with space volume restrictions, sealing restrictions, and high-torque rotation restrictions, such as petroleum downhole power transmission mechanisms.

Therefore, for low-speed, high-torque, variable-angle constant-velocity transmission applications, the present invention proposes a novel composite slider-type constant velocity universal joint and universal joint transmission device.

Contents of the invention

The object of the present invention is to provide a composite slider type constant velocity universal joint, which is suitable for low-speed, high-torque, variable-angle, constant-velocity transmission applications.

In the first aspect, the present invention provides a composite slider type constant velocity universal joint, which includes a spline-like shaft, an axial limit end cover assembly, a composite slider assembly and a housing, and the outer peripheral surface of the spline-like shaft A plurality of spline-like protrusions are arranged around the upper surface, and a plurality of spline-like grooves matching the spline-like protrusions and the composite slider assembly are arranged around the inner peripheral surface of the housing. The spline-like shaft is connected to the casing through the composite slider assembly, and the axial limit end cover assembly is sealed and arranged in the annular gap between the spline-like shaft and the casing .

As a preferred solution of this technical solution, the composite slider assembly includes multiple sets of slider groups and multiple sets of gap compensation springs, each set of slider groups includes a first slider and a second slider, and the first slider The block is arranged in the limit groove on the spline-like protrusion, and one side of the first slider and the other first slider in the adjacent slider group are made up by the gap The springs achieve elastic contact and mutual support, the other side of the first slider is connected to one side of the second slider in a spherical pair, and the other side of the second slider is connected to the spline-like groove. The inner side wall is connected by a semi-open cylinder sleeve pair.

Preferably, as the technical solution, each of the spline-like protrusions is provided with two limiting grooves in parallel and symmetrically, and one or more through holes are opened on the side wall between the two limiting grooves, so that The gap compensating spring is correspondingly arranged in the through hole, and the two ends of the gap compensating spring respectively abut one side of the two first sliders in the adjacent slider groups.

Preferably, as the technical solution, the sides where the first slider and the second slider are connected by a spherical pair are respectively a concave surface and a convex surface that cooperate with each other.

Preferably as this technical solution, a rolling ball is arranged between the first slider and the second slider, and the surfaces of the first slider and the second slider that are in contact with the rolling ball Both are concave, and both the first slider and the second slider are connected with the rolling ball in a spherical pair.

Preferably, as the technical solution, the axial limit end cover assembly includes a snap ring, a limit end cover and an end cover lock block, and the snap ring, the limit end cover and the end cover lock block are sequentially inserted It is arranged on the spline-like shaft and is located in the annular gap between the spline-like shaft and the housing, wherein the outer side of the limiting end cap is provided with external threads, and the housing and Internal threads are provided inside the end cover locking blocks, and the housing and the end cover locking blocks are respectively threaded with the limiting end caps.

Preferably, as the technical solution, a sealing member is further included, and the sealing member is arranged between the position-limiting end cap and the end cap locking block.

As a preferred solution of this technical solution, the sealing member includes a cup pad.

Preferably, as the technical solution, a spherical sub-base is detachably provided in the housing, and a spherical sub-structure matching the spherical sub-base is provided at one end of the spline-like shaft close to the housing.

In the second aspect, the present invention also discloses a universal joint transmission device provided with the composite slider type constant velocity universal joint, which should also belong to the protection scope of the present invention. Moreover, the universal joint transmission device has the same advantages as the above-mentioned composite slider type universal joint compared with the prior art.

Compared with the prior art, the composite slider type constant velocity universal joint of the present invention has at least the following technical effects:

1. The composite slider type constant velocity universal joint of the present invention includes a spline-like shaft, an axial limit end cover assembly, a composite slider assembly and a housing, wherein the outer peripheral surface of the spline-like shaft is surrounded by multiple There are a plurality of spline-like protrusions, and a plurality of spline-like grooves matching the spline-like protrusions and the composite slider assembly are arranged around the inner peripheral surface of the housing. When the composite slider type constant velocity universal joint of the present invention is applied to the universal joint transmission device, the driving shaft is inserted into the spline hole of the spline-like shaft, and the driving shaft transmits power to the The spline-like shaft, the spline-like shaft transmits the power to the housing through the composite slider assembly, and then directly transmits the power to the driven shaft; when the angle between the driving shaft and the driven shaft changes, the composite slider The composite slider assembly in the constant velocity universal joint slides in the spline-like projection of the spline-like shaft and the spline-like groove of the housing, and through the spherical low pair of the composite slider, it adapts to the relationship between the drive shaft and the drive shaft. The angle between the shafts changes to realize the multi-point equal-load and constant-speed transmission of torque from the spline-like shaft to the housing;

2. The composite slider-type constant velocity universal joint of the present invention realizes the space variable angle function of the fixed connection point through the spherical joint structure composed of the spline-like shaft and the housing, the axial limit end cover assembly and the composite slider assembly and axial bearing function. The composite slider assembly is a plurality of sets of sliders that are ball-milled with each other. The corresponding sides of the spherical surfaces of the parallel sliders form a low pair with a total degree of freedom of 1. The composite slider assembly can meet multiple requirements. The point flexible transmission mechanism requires degrees of freedom. When the angle between the driving shaft and the driven shaft changes, the composite slider assembly can move the center of the spherical pair outward to achieve contact with a large radius spherical surface, thereby realizing large torque transmission. The position of the high-speed pair at the position of the flexible point can ensure the low-stress requirements of the high-side by adjusting the radius of the spherical surface, so that it is suitable for low-speed, high-torque, variable-angle, and constant-speed transmission applications.

Description of drawings

In order to more clearly illustrate the specific implementation of the present invention or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings that need to be used in the specific implementation or description of the prior art. Obviously, the accompanying drawings in the following description The drawings show some implementations of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative work.

Fig. 1 is a schematic diagram of the design principle of the composite slider type constant velocity universal joint of the present invention;

Fig. 2 is an exploded view of the compound slider type constant velocity universal joint structure of the present invention;

Fig. 3 is a sectional view of the compound slider type constant velocity universal joint shaft of the present invention;

Fig. 4 is a cross-sectional view of the flexible joint of the compound slider type constant velocity universal joint of the present invention;

Fig. 5 is a schematic diagram of the connection between the axial limit end cover assembly and the spline-like shaft of the present invention;

Figure 6 is the second schematic diagram of the connection between the axial limit end cover assembly and the spline-like shaft of the present invention;

Fig. 7 is a schematic diagram of a composite slider assembly of the present invention;

Fig. 8 is the second schematic diagram of the composite slider assembly of the present invention.

Explanation of reference signs:

1: spline-like shaft; 2: housing; 3: spline-like protrusion; 4: spline-like groove; 5: slider group; 6: gap compensation spring; 7: first slider; 8: second slider block; 9: limit groove; 10: through hole; 11: rolling ball; 12: snap ring; 13: limit end cover; 14: end cover lock block; 15: seal; 16: spherical sub-base; 17 : input shaft; 18: output shaft; 19: fixed node of input shaft; 20: fixed node of output shaft; 21: flexible transmission node.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

In describing the present invention, it is to be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " Back", "Left", "Right", "Straight", "Horizontal", "Top", "Bottom", "Inner", "Outer", "Clockwise", "Counterclockwise", etc. or The positional relationship is based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, Therefore, it should not be construed as limiting the invention.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of said features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined. In addition, the terms "installation", "connection" and "connection" should be interpreted in a broad sense, for example, it can be fixed connection, detachable connection, or integral connection; it can be mechanical connection or electrical connection; it can be It can be directly connected, or indirectly connected through an intermediary, and can be internal communication between two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations.

As shown in Figures 1-8, this embodiment provides a composite slider type constant velocity universal joint, including a spline-like shaft 1, an axial limit end cover assembly, 5 composite slider groups and a housing 2, The outer peripheral surface of the spline-like shaft 1 is surrounded by a plurality of spline-like protrusions 3 , and the inner peripheral surface of the housing 2 is surrounded by a plurality of spline-like protrusions 3 and the described spline-like protrusions 3 . The spline-like groove 4 that is suitable for the composite slider assembly, the spline-like shaft 1 is in transmission connection with the housing 2 through the composite slider assembly, and the axial limit end cover assembly is sealed and arranged on the In the annular gap between the spline-like shaft 1 and the housing 2 .

Fig. 1 is a schematic diagram of the design of the composite slider type constant velocity universal joint in this embodiment, the input shaft 17 and the output shaft 18 respectively output from the input shaft fixed node 19 and the output shaft fixed node 20 intersect at the flexible transmission node 21, According to the calculation principle of the degree of freedom of the kinematic chain, this universal joint is designed with multiple sets of slider groups 5 that cooperate with each other on spherical surfaces. The composite slider assembly with this structure just satisfies the degree-of-freedom requirements of the flexible transmission node 21 in Fig. 1 , and thus can meet the freedom-degree requirements of the multi-point flexible transmission mechanism.

When the composite slider type constant velocity universal joint of this embodiment is applied to the universal joint transmission device, the driving shaft transmits power to the spline-like shaft 1 through any type of coupling structure, and the spline-like shaft 1 will The power is transmitted to the housing 2 through the compound slider assembly, and then the power is directly transmitted to the driven shaft; when the angle between the driving shaft and the driven shaft changes, the compound slider in the compound slider type constant velocity universal joint The block assembly can slide in the spline-like protrusion 3 of the spline-like shaft 1 and the spline-like groove 4 of the housing 2, and realize the spherical low pair motion through the spherical pair of the compound slider assembly to adapt to the driving shaft and the transmission shaft The angle between the shafts changes, and then the multi-point load equalization and constant velocity transmission of the composite slider type constant velocity universal joint is realized. The composite slider type constant velocity universal joint of the present invention can realize equal load and constant velocity torque transmission with more than four contact points of the same order as the spherical cage universal joint.

On the basis of the above technical solution, the composite slider assembly specifically includes multiple sets of slider sets 5 and multiple sets of gap compensation springs 6, and each set of slider sets 5 includes a first slider 7 and a second slider 8. The first slider 7 is set in the limiting groove 9 on the spline-like protrusion, and one side of the first slider 7 is connected to the other side of the adjacent slider group 5 The first slider 7 realizes elastic contact and mutual support through the gap compensation spring 6, and the other side of the first slider 7 is connected to one side of the second slider 8 in a spherical pair, and the The other side of the second slider 8 is connected with the inner sidewall of the spline-like groove 4 in a semi-open cylindrical sleeve pair.

The connection between the first slider 7 and the second slider 8 in each slider group 5 is a spherical pair and a lower pair. The composite slider assembly can adapt to the change of the angle between the spline-like shaft 1 and the housing 2 and automatically Evenly distribute the circumferential force to each slider group 5. The slider group 5 can move the spherical center of the spherical pair outward to realize the contact of the large radius spherical surface, and then realize the position of the high pair at the flexible point position during large torque transmission. The radius of the spherical surface ensures the requirement of high pair and low stress, so it is suitable for low-speed, high-torque, variable-angle and constant-speed transmission applications. The setting of the gap compensation spring 6 further ensures the stability of the composite slider assembly when the large torque is transmitted at variable angles, and can automatically compensate for the gap caused by the increased accuracy and design accuracy, ensuring that the non-loaded side can maintain the preload during transmission. .

On the basis of the above technical solution, further, each of the spline-like protrusions 3 is provided with two parallel and symmetrical limiting grooves 9 to accommodate the two first sliders 7 in the adjacent slider group 5 respectively. One or more through holes 10 are opened on the side wall between the two limiting grooves 9, the gap compensation spring 6 is correspondingly arranged in the through holes 10, and the two gap compensation springs 6 The ends are respectively against one side of the two first sliders 7 in the adjacent slider group 5, that is, the two adjacent first sliders 7 are elastically connected by a gap compensation spring 6 Yes, the side of the first slider 7 away from the gap compensating spring 6 is connected to the second slider 8 in a spherical pair, and the side of the second slider 8 away from the first slider 7 is connected to the inner peripheral surface of the housing 2. The spline grooves 4 are offset, that is, the spline-like grooves 4 inside the housing 2 can just accommodate two adjacent sets of sliders 5 and the spline-like projections 3 that fix the adjacent two sets of sliders 5 .

In a specific embodiment of the present invention, the first slider 7 and the second slider 8 are connected in a spherical pair, specifically means that the sides where the first slider 7 and the second slider 8 are in contact are respectively Concave and convex surfaces that cooperate with each other. When the angle between the driving shaft and the driven shaft is relatively large, the composite slider assembly can move the center of the spherical pair outward to realize the contact of the large-radius spherical surface, and then realize the high-pair position at the flexible point position during large torque transmission. The requirement of high and low stress can be guaranteed by adjusting the radius of the spherical surface.

In another specific embodiment of the present invention, a rolling ball 11 is arranged between the first slider 7 and the second slider 8, and the first slider 7 and the second slider 8 and the surface in contact with the rolling ball 11 are both concave, and the first slider 7 and the second slider 8 are both connected to the rolling ball 11 in a spherical pair. This structure turns the ball and arc-shaped raceway structure of the traditional spherical cage joint into a spherical contact pair. Therefore, although the structure does not move the center of the spherical pair to increase the radius to reduce the contact stress, the structure The structure can ensure the rolling performance of the rolling ball 11 under heavy load. Therefore, this structure not only solves the problem of constant speed transmission at low speed and high torque with variable angle, but also solves the problem that the rolling ball 11 does not roll under the high torque of the traditional ball cage universal joint.

What needs to be explained here is that the composite slider assembly of the present invention includes but is not limited to the above two forms, and other double-slider structures that meet the positional freedom requirements of the flexible transmission node in Fig. 1 can also be selected.

On the basis of the above technical solution, in order to further realize the axial position limitation of the spline-like shaft 1 and the housing 2, a shaft with a concave spherical structure and an inner diameter smaller than the maximum diameter of the spline-like shaft 1 is connected to the open end of the housing 2 However, the present invention does not strictly limit the specific composition and structure of the axial limit end cap assembly. According to different spline-like shaft 1 structures, axial limit end caps with different structures and compositions can be selected. components.

As shown in FIG. 5 , in an embodiment of the present invention, an integral limit end cap is selected, and the integral limit end cap can be directly slid into the end of the spline-like shaft 1 away from the spline-like protrusion 3 .

As shown in Figure 6, in another embodiment of the present invention, a split-type limit end cap is selected, and the split-type limit end cap slides in from the end of the spline-like shaft 1 close to the spline-like protrusion 3 respectively, Specifically, the axial limit end cap assembly includes a snap ring 12, a limit end cap 13, and an end cap lock block 14. The spline structure of the snap ring 12 and the limit end cap 13 has the following characteristics: the spline The number is equal to the spline-like quantity of the spline-like shaft; the spline widths of the snap ring 12 and the limit end cap 13 are equal to complement each other; the splines of the snap ring 12 and the limit end cap 13 The width of the key is smaller than the width between the spline-like protrusions of the spline-like shaft, so that the snap ring 12 and the limit end cover 13 can slide in by changing the angular relative position of the spline-like shaft, the snap ring 12, the The limiting end cap 13 and the end cap locking block 14 are sequentially sleeved on the spline-like shaft 1 and located at the joint between the spline-like shaft 1 and the housing 2, wherein the limiting The outside of the end cover 13 is provided with external threads, and the inside of the housing 2 and the end cover lock block 14 are all provided with internal threads, and the housing 2 and the end cover lock block 14 are respectively connected to the limit Bit end cap 13 threaded connections.

Whether it is an integral limit end cover or a split limit end cover, it is finally connected to the housing 2 through the end cover lock cover, and then cooperates with the function of the housing 2 to limit the axial movement of the spline shaft 1, which can realize The restriction on the position of the spline-like shaft 1 can also meet the bearing requirements of the axial force of the universal joint in some occasions, and improve the stability of the universal joint transmission device when transmitting power.

On the basis of the above technical solution, in order to further realize the sealing between the spline-like shaft 1 and the housing 2, and prevent dust and impurities in the external environment from entering into the universal joint. The composite slider type constant velocity universal joint in this embodiment also includes a seal 15, the large diameter end of which is arranged between the limit end cover 13 and the end cover lock block 14, and its small diameter The end fits and seals on the spline-like, 1 smooth peripheral surface, and the seal 15 includes but not limited to a cup pad.

When selecting the leather bowl pad to seal, the end cover lock block 14 is fixed and sealed on the large mouth side of the leather bowl pad, and the small mouth side of the leather bowl pad is tightly sealed on the circumferential surface of the flower-like shaft 1.

On the basis of the above-mentioned technical solution, it is further preferred that the housing 2 is a housing 2 containing a spherical pair, or a housing 2 with a spherical sub-base 16 detachably arranged inside, and a spline-like spline is used. The end of the shaft 1 close to the housing 2 is provided with a spherical sub-structure compatible with the spherical sub-base 16 to reduce wear on the spline-like shaft 1 and the housing 2 during power transmission.

The embodiment of the present invention also provides a universal joint transmission device provided with the above-mentioned composite slider type constant velocity universal joint. Compared with the above-mentioned composite slider type constant velocity universal joint, the universal joint transmission device The advantages of the technology are the same and will not be repeated here.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. scope.

Claims (10)

1. A compound slider type constant velocity universal joint, characterized in that it comprises a spline-like shaft (1), an axial limit end cap assembly, a composite slider assembly and a housing (2), The outer peripheral surface of the spline-like shaft (1) is surrounded by a plurality of spline-like protrusions (3), and the inner peripheral surface of the housing (2) is surrounded by a plurality of spline-like protrusions (3). The protrusion (3) is adapted to the spline-like groove (4) of the composite slider assembly, and the spline-like shaft (1) is in drive connection with the housing (2) through the composite slider assembly, The axial limit end cover assembly is sealed and arranged in the annular gap between the spline-like shaft (1) and the housing (2). 2. The composite slider type constant velocity universal joint according to claim 1, characterized in that, the composite slider assembly includes multiple groups of slider groups (5) and multiple groups of gap compensation springs (6), Each set of slider groups (5) includes a first slider (7) and a second slider (8), and the first slider (7) is arranged on the spline-like protrusion (3) In the limiting groove (9), and one side of the first slider (7) and the other first slider (7) in the adjacent slider group (5) pass through the gap The compensation spring (6) realizes elastic contact and mutual support, and the other side of the first slider (7) is connected with a side of the second slider (8) in a spherical pair, and the second slider ( 8) The other side is connected with the inner side wall of the spline-like groove (4) in a semi-open cylindrical sleeve pair. 3. The composite slider type constant velocity universal joint according to claim 2, characterized in that, each said spline-like protrusion (3) is provided with two limiting grooves (9) parallel and symmetrical, and the two One or more through holes (10) are provided on the side wall between the two limiting slots (9), The gap compensation spring (6) is correspondingly arranged in the through hole (10), and the two ends of the gap compensation spring (6) are respectively connected to the two adjacent slider groups (5). One side of the first slide block (7) offsets. 4. The composite slider-type constant velocity universal joint according to claim 2, characterized in that, the sides where the first slider (7) and the second slider (8) are connected by a spherical pair are respectively Concave and convex surfaces that cooperate with each other. 5. The composite slider type constant velocity universal joint according to claim 2, characterized in that, a rolling ball (11) is arranged between the first slider (7) and the second slider (8) ), and the surfaces of the first slider (7) and the second slider (8) in contact with the rolling ball (11) are concave, and the first slider (7) and the The second sliders (8) are all connected with the rolling balls (11) in a spherical pair. 6. The composite slider type constant velocity universal joint according to claim 1, characterized in that, the axial limit end cover assembly includes a snap ring (12), a limit end cover (13) and an end cover lock block(14), The snap ring (12), the limit end cover (13) and the end cover lock block (14) are sequentially sleeved on the spline-like shaft (1) and positioned on the spline-like shaft ( In the annular gap between 1) and the housing (2), Wherein, the outer side of the limit end cap (13) is provided with external threads, the inside of the housing (2) and the end cap locking block (14) are all provided with internal threads, and the housing (2) and the end cover lock block (14) are respectively threaded with the limit end cover (13). 7. The composite slider type constant velocity universal joint according to claim 6, characterized in that it further comprises a seal (15), the seal (15) is arranged on the limit end cover (13) and between the end cover lock blocks (14). 8. The compound slider type constant velocity universal joint according to claim 7, characterized in that, the sealing member (15) comprises a cup pad. 9. The composite slider type constant velocity universal joint according to claim 1, characterized in that, a spherical sub-base (16) is detachably arranged in the housing (2), and the spline-like shaft ( 1) A spherical sub-structure adapted to the spherical sub-base (16) is provided near one end of the housing (2). 10. A universal joint transmission device, characterized in that the universal joint transmission device is provided with the composite slider type constant velocity universal joint according to any one of claims 1-9.

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