Cardan Joint

Description

TECHNICAL FIELD The present invention relates to a toy fork pin according to the preamble of claim 1, a toy fork receptacle according to claim 9, and a cardan joint according to claim 10.

BACKGROUND

A toy fork pin according to the preamble of current claim 1 is known from the European Community design 008337372-0008.

SUMMARY

It is the object of the present invention to improve the known toy component.

Starting from a toy fork pin that can be plugged together with a toy fork receptacle to form a cardan joint, with a torque transmission piece for receiving or transmitting a torque about an insertion direction, with a wall-shaped carrier piece arranged on the torque transmission piece and extending in the insertion direction as well as in a nodding direction transverse to the insertion direction, and with a ball element mounted, in the insertion direction, opposite the torque transmission piece on the wall-shaped carrier piece, the toy fork pin according to the invention comprises at least one wall-shaped joint needle piece held on the ball element, which extends in the insertion direction and in a yawing direction extending transverse to the insertion direction and transverse to the nodding direction.

The given toy fork pin is based on the idea of relocating slots for receiving joint needle pieces from the known toy fork pin into the toy fork receptacle. In this way, forces can be distributed more effectively and wear can be minimized. This leads to smoother and more efficient power transmission as well as optimized mobility of a cardan joint formed from a toy fork pin and a toy fork receptacle. A cardan joint is to be understood hereinafter as a mechanical component that enables the transmission of torque at variable bend angles between two shafts that it connects. This bend-angle-variable transmission of torque is achieved by two degrees of freedom: a rotational movement about a longitudinal axis aligned in the insertion direction, and a pivoting movement about a transverse axis aligned perpendicular to the insertion direction.

In detail, relocating the slots into the toy fork receptacle improves mechanical stability, since the toy fork receptacle tends to be more massive and stable, which enables better load distribution and reduced material fatigue. The joint needle piece on the toy fork pin reduces wear, since the toy fork pin tends to be subject to less play and less load than the toy fork receptacle, which increases the service life of the cardan joint. Slots in the toy fork receptacle are easier to maintain, since they are more accessible. This facilitates regular disassembly and improves the functionality and service life of the cardan joint, particularly in its application as a toy. By swapping the positions, the movement angle is optimized, since the slots in the toy fork receptacle offer greater freedom of movement than in the toy fork pin, resulting in a larger bend angle. A more stable mounting of the joint needle pieces on the toy fork pin also helps to minimize play and vibrations in the joint, which leads to smoother and more efficient transmission of forces. The swapping also optimizes manufacturing tolerances, since the slots in the toy fork receptacle can be manufactured and controlled more precisely, improving the fitting accuracy and function of the cardan joint.

In one refinement of the specified toy fork pin, the wall-shaped carrier piece comprises a post from which, in and counter to the nodding direction, one wall element projects in each case. In this way, the structural stability can be increased. The arrangement enables a more uniform distribution of the forces acting on the toy fork pin, which leads to improved load capacity and reduced material fatigue. The wall elements projecting on both sides also provide more precise guidance of the joint needle pieces, which further optimizes movement accuracy and the efficiency of torque transmission. In addition, this construction increases torsional stiffness, thereby minimizing undesirable twisting and extending the service life of the cardan joint. Finally, the clearly defined structure of the post with the projecting wall elements simplifies manufacturing and assembly, since the components can be positioned and fixed more precisely.

In an additional refinement of the specified toy fork pin, the post tapers conically in the insertion direction. In this way, the fitting accuracy and self-centering of the toy fork pin can be improved. The conical shape facilitates the insertion of the shaft connection piece into the toy fork receptacle, which simplifies and speeds up assembly. Furthermore, the conical taper ensures a more uniform distribution of the contact forces along the insertion direction, which reduces wear and increases the service life of the cardan joint. The conical shape also minimizes undesirable play by ensuring a precise and firm connection, resulting in smoother and more efficient torque transmission. Finally, the conical taper allows for higher tolerance to manufacturing deviations, since the self-centering property of the conical shape compensates for minor inaccuracies and thus improves the overall functionality and reliability of the cardan joint.

In another refinement of the specified toy fork pin, the post is coaxially arranged on a socket formed on the torque transmission piece, which tapers conically towards the ball element. In this way, the structural integrity and stability can be increased. The conical socket ensures improved force distribution in supporting the ball element, which increases the load capacity and service life of the cardan joint. The coaxial alignment further increases the precision of centering, which simplifies assembly and improves fitting accuracy. The conical taper of the socket also enables effective self-centering and facilitates the insertion of the post, which simplifies handling and assembly. This contributes to reduced friction and minimal play, resulting in smoother and more efficient torque transmission. Furthermore, the conical shape improves torsional stiffness and minimizes undesirable twisting, which further optimizes the functionality and reliability of the cardan joint in its application as a toy.

In yet another refinement of the specified toy fork pin, the sides of the wall elements, viewed in and counter to the nodding direction, are designed to converge towards each other in the direction of the ball element. In this way, the bend angle of the cardan joint, i.e. the angle at which the two shafts connected to each other by the cardan joint can be angled relative to one another, can be increased. In detail, the converging design of the wall elements enables greater freedom of movement of the ball element, as the movement space is expanded and is subject to fewer restrictions. As a result, the ball element can be pivoted at a larger angle, which leads to increased angular variability and flexibility of the cardan joint. This increased mobility improves the ability of the cardan joint to efficiently transmit torque at larger angles and contributes to optimized functionality. In addition, this design ensures a more even distribution of the forces occurring and thus minimizes wear and material fatigue, which extends the service life of the cardan joint. The more precise guidance of the ball element and the increased freedom of movement lead to smoother and more efficient torque transmission, which improves the overall performance of the cardan joint, particularly in its application as a toy.

In a further refinement of the specified toy fork pin, the ball element, viewed in the nodding direction, is formed with a smaller extension than an extension of the wall-shaped carrier piece, preferably a minimum extension of the wall-shaped carrier piece. In this way, the aforementioned bend angle of the cardan joint can be further increased, because the reduced extension of the ball element in the nodding direction additionally enlarges the movement space for the pivoting movement, which supports the converging strategy and further increases the maximum angle that the joint can achieve. This refinement enables even greater angular variability and flexibility, allowing the cardan joint to efficiently transmit torque at even more extreme angles. The reduced extension of the ball element compared to the wall-shaped carrier piece also minimizes potential contact points and friction surfaces between the ball element and the adjacent components, which further reduces wear and increases the service life of the cardan joint. Additionally, the smaller extension leads to improved freedom of movement and precision, as there are fewer physical constraints that could hinder movement. This results in smoother and more efficient torque transmission and improves the overall performance and reliability of the cardan joint, particularly in its application as a toy.

In a special refinement of the specified toy fork pin, the joint needle piece, viewed in the yawing direction, has a trapezoidal, preferably rhombic, cross-section, wherein a main diagonal of the trapezoidal cross-section is aligned in the insertion direction. In this way, force distribution can be further improved and thus stability further increased. The trapezoidal or rhombic cross-section enables optimal distribution of the forces acting on the joint, which increases load capacity and reduces material fatigue. By aligning the main diagonal in the insertion direction, the forces are efficiently guided along the strongest axis of the cross-section, which improves the structural integrity of the joint. The cross-sectional shape also increases the freedom of movement of the joint, as it offers fewer physical constraints and allows for greater flexibility. This contributes to a larger bend angle, since the joint needle piece has more movement space and is less easily blocked. Furthermore, the trapezoidal or rhombic cross-section ensures more precise guidance and a more stable connection between the components, which increases the functionality and reliability of the cardan joint. The geometric shape of the joint needle piece also facilitates manufacturing and assembly, as the clearly defined edges and surfaces allow for precise production and easy fitting accuracy. Overall, the trapezoidal, and especially the rhombic, cross-sectional shape leads to smoother and more efficient torque transmission, an extended service life of the cardan joint, and optimized performance, particularly in its application as a toy.

In a preferred refinement, the toy fork pin is designed to be rotationally symmetrical about a rotation axis aligned in the insertion direction, with a rotational symmetry angle of 180°.

In this context, rotational symmetry (German: Drehsymmetrie) is to be distinguished from continuous rotational symmetry (German: Rotationssymmetrie), although both terms describe the symmetry of an object about an axis. Rotational symmetry exists when an object is rotated about a certain axis and thereby assumes multiple stable positions in which it appears identical. This symmetry generally refers to discrete rotation angles. An example of this is a regular hexagon, which appears identical after a rotation of 60°, 120°, 180°, 240°, 300°, and 360°. Continuous rotational symmetry, on the other hand, describes an object that can be rotated about a central axis by any arbitrary angle and appears identical in every position. This symmetry is continuous and does not refer to discrete rotation angles, but rather to continuous ones. An example of this is a circle, which appears identical after a rotation by any arbitrary angle. The distinction between the two terms therefore lies in the fact that rotational symmetry (German: Drehsymmetrie) typically refers to discrete, specific rotation angles at which the object appears identical, while continuous rotational symmetry (German: Rotationssymmetrie) refers to the continuous symmetry of an object about an axis, in which the object remains identical at any arbitrary rotation.

If the toy fork pin is designed to be rotationally symmetrical about a rotation axis aligned in the insertion direction, the uniformity and stability of torque transmission can be improved. Rotational symmetry ensures that the forces are evenly distributed around the rotation axis, which leads to reduced load on individual areas and more uniform wear. This reduces wear and increases the service life of the cardan joint. Rotational symmetry also simplifies the assembly and adjustment of the toy fork pin, since the symmetrical shape enables precise alignment. This leads to higher fitting accuracy and reduces the risk of assembly errors. In addition, the rotationally symmetrical design allows uniform rotation without imbalances, which contributes to smoother and more efficient torque transmission. Another advantage of rotational symmetry is increased manufacturing efficiency. Symmetrical parts are easier and more cost-effective to produce, since the geometry is less complex and standardized manufacturing techniques can be used. This can lead to a reduction in production costs and an improvement in quality control.

According to a further aspect of the invention, a toy fork receptacle for receiving one of the specified toy fork pins comprises a torque transmission piece for receiving or transmitting a torque about an insertion direction, and a receiving piece arranged on the torque transmission piece and rising cylindrically in the insertion direction, with a receiving opening formed, in the insertion direction, opposite the torque transmission piece, into which the ball element can be inserted into a receiving space, wherein slots for receiving the wall-shaped carrier piece and the joint needle piece are formed in the walls of the receiving space, as viewed in the nodding direction and in the yawing direction.

According to a further aspect of the invention, a cardan joint comprises one of the specified toy fork pins and a specified toy fork receptacle, wherein the ball element of the toy fork pin is inserted into the receiving space of the toy fork receptacle.

The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become more comprehensible in connection with the following description of the exemplary embodiments, which are explained in greater detail in connection with the drawings.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 is a side view of a cardan joint composed of a toy fork receptacle and a toy fork pin,

FIG. 2 is a perspective view of a toy fork pin for the cardan joint from FIG. 1, and

FIG. 3 is a perspective view of a toy fork receptacle for the cardan joint from FIG. 1.

In the figures, identical technical elements are provided with the same reference numerals and are described only once. The figures are purely schematic and, in particular, do not represent the actual geometric proportions.

DETAILED DESCRIPTION

Reference is now made to FIG. 1, which is used to describe in more detail a cardan joint 2 that is composed of a toy fork receptacle 4 and a toy fork pin 6 movably held in the toy fork receptacle 4.

The cardan joint 2 is a mechanical component installable between two shafts (not shown) that can be used. The shafts are inserted in an insertion direction 8 into a corresponding torque transmission piece 10, which can transmit torques 12 about the insertion direction 8 between the two shafts. The shafts are here merely illustrative machine elements that may serve as a torque source or torque sink. The torque transmission pieces 10 can be attached to any machine elements for torque transmission, such as wheel hubs in connection with vehicle steering, where cardan joints play a key role.

The cardan joint 2 enables the transmission of the torques 12 at variable bend angles 14 between two rotation axes 16 about which the torques 12 act. This bend-angle-variable transmission of the torques 12 is achieved by two degrees of freedom, namely by a rotational movement about the respective rotation axis 16 and a pivoting movement in the direction of the bend angle 14.

The movable joint partners, i.e., the toy fork receptacle 4 and the toy fork pin 6, are hereinafter considered in separate coordinate systems, since, due to the movability of the two joint partners 4, 6 relative to each other, a meaningful description in a common coordinate system would significantly complicate the further explanations. Each joint partner 4, 6 therefore has its own coordinate system hereinafter, with the insertion direction 8 aligned in the rotation axis 16, a yawing direction 18 perpendicular to the insertion direction 8, and a yawing direction 20 perpendicular to the insertion direction 8 and perpendicular to the nodding direction 18. The reason for the naming of these directions 8, 18, 20 arises only from the further description and will not be discussed in detail here for the sake of brevity.

Reference is now made to FIG. 2, which in a perspective view shows an example of the toy fork pin 6 for the cardan joint 2 from FIG. 1.

The toy fork pin 6 comprises, as a torque transmission piece 10, a shaft connection piece into which a shaft (not shown) can be inserted. As a shaft in the toy application area, for example, a cross axle is suitable, such as that catalogued by the company Lego A/S under part number 4519 on the website www.bricklink.com. The cross shape is shown later in FIG. 3. For receiving such a cross axle, the torque transmission piece 10 is formed with a receiving space (not further shown) into which the cross axle can be inserted in the insertion direction 8, the cross shape ensuring that forces transverse to the insertion direction 8 take up the torque 12 about the rotation axis 16 and that the cross axle is held in a form-fitting manner on the torque transmission piece 10.

Viewed in the insertion direction 8, a wall-shaped carrier piece 22 is attached to the torque transmission piece 10, which is set up in the insertion direction 8 and extends in the nodding direction 20. The wall-shaped carrier piece 22 is, in the present embodiment, designed in three parts and has a post 24 on whose front side and rear side, viewed in the nodding direction 20, one wall element 26 each is connected. The post 24 is conically shaped and concentrically mounted on a conical end piece 27 at the front end, in the insertion direction 8, of the torque connection piece 10.

The wall elements 26, viewed in the nodding direction 20, have on their sides opposite the post 24 outer edges 28, which, viewed in the insertion direction 8, converge towards each other. This means that a distance (not further referenced in the figures) between the two outer edges 28 decreases with increasing distance in the insertion direction 8. The outer edges 28 are each provided with a step 30, with only one of the two steps 30 being visible and therefore referenced in the view of FIG. 2. The technical background of this step will be discussed in more detail at a later point.

In the region of the step 30, the wall elements 26 act like fork prongs, between which a ball element 32 is held. This ball element 32 is seated on the post 24 and is gripped by the wall elements 26 in and counter to the nodding direction 20. In this way, the ball element 32 is stably supported by the wall-shaped carrier piece 22.

On the ball element 32, in and counter to the yawing direction 18, one joint needle piece 34 each is held. The joint needle pieces 34 in the present embodiment are rhombic in shape and aligned with their main axis in the insertion direction 8. In principle, the joint needle pieces 34 can also be otherwise formed wall-shaped, meaning that their extension in the insertion direction 8 is greater than in the nodding direction 20. The function of the joint needle pieces 34 is related to the technical effect of the cardan joint 2 to be formed, which will be explained in more detail at a later point.

The toy fork pin 6 is rotationally symmetrical about the rotation axis 6, with a rotational symmetry angle of 180°, not further referenced in the figures. This means that when the toy fork pin 6 is rotated by 180°, it appears the same to an observer viewing the toy fork pin 6 from a given position as it did in the original position.

Reference is now made to FIG. 3, which, in a perspective view, shows an example of the toy fork receptacle 4 for the cardan joint 2 from FIG. 1.

The toy fork receptacle 4 is constructed analogously to the toy fork pin 6 and likewise extends in the insertion direction 8, with the torque connection piece 10 arranged at the rear end in the insertion direction 8. In the present embodiment, this is designed as the aforementioned cross axle and has two cross axle walls 36 held perpendicular to each other, which extend in the yawing direction 18 and in the nodding direction 20 respectively, and together form the cross shape visible in FIG. 3.

Connected to the torque connection piece 10 in the form of the cross axle is a cylindrical receiving piece 38, into which the ball element 32 of the toy fork pin 6 can be inserted.

For this purpose, the receiving piece 38 has a receiving opening 40, through which the ball element 32 can be inserted, in a manner to be described later, into a receiving space 42 of the receiving piece 38.

On the walls of this receiving space 42 there are slots, with a semicircular slot 44 starting from the receiving opening 40, running over a bottom of the receiving space 42 (not further shown), and returning to the receiving opening 40. Furthermore, wall slots 46, opening from the receiving space 42 outward in the nodding direction 20, are formed into the walls of the receiving space 42.

The wall slots 46 are followed, counter to the insertion direction 8, by receiving grooves 48, while play spaces 50 are formed around the two end regions of the semicircular slot 44. In FIG. 3, only one of the receiving grooves 48 and one of the play spaces 50 are provided with their own reference numeral.

To assemble the cardan joint 2, the toy fork receptacle 4 with the wall slots 48 and the toy fork pin 6 with the wall-shaped carrier piece 22 are first aligned in the nodding direction 20. The wall-shaped carrier piece 22 is then inserted into the wall slots 48, and the toy fork receptacle 4 and the toy fork pin 6 are each moved in their insertion direction 8, so that the wall-shaped carrier piece 22 is introduced into the wall slots 48. In this way, at the same time, the joint needle pieces 34 are inserted into the semicircular slot 44, whereby the toy fork pin 6 can be rotated relative to the toy fork receptacle 4 in the yawing direction 18 (referred to as yawing) and in the nodding direction 20 (referred to as nodding).

Through the receiving grooves 48, the play spaces 50, and the step 30, a maximum range of movement for nodding and yawing is ensured, which leads to a maximum possible bend angle 14.