Push chain device comprising a toothed sprocket with long asymmetrical teeth

Abstract

The present invention relates to a push chain device, comprising: a push chain (10) including a curved portion (10b) and a straight portion (10a) along an axis, the chain including links (12) hinged to the axis; a push chain guide (20); a drive sprocket (1) having teeth (2) interlocked with the push chain, the sprocket contacting the push chain through a circular involute-shaped contact surface (2a), the contact surface (2a) being a tooth, the teeth (2) engaging with the chain, and defining a line of action at an angle between -10° and 10° to the axis of the straight portion, the line of action being offset relative to the hinge axis of the link, the sprocket contacting the straight portion (10a) but not the curved portion (10b), and being mounted such that it can rotate on an axis located on the side of the chain opposite to the center of curvature of the curved portion (10b), the contact surface (2a) including a convex front surface toward the straight portion (10a) and a rear surface toward the curved portion (10b) when the teeth (2) interlock.

Description

Technical Field

[0001] This invention relates to thrust-load moving machinery, and more particularly to transmission components for such machinery. Background Technology

[0002] In applications requiring long-stroke, high-load motion with limited available space, chain-driven machinery known to use rigid chains is known. FR2786476, on behalf of the applicant, describes an articulated load-bearing column using a rigid chain.

[0003] Rigid chain or hinged rod mechanics allows the chain to be moved from a folded state, occupying a small overall size, to an unfolded state, which can withstand high compressive loads in a straight, rigid structural form.

[0004] Compared to cylinders, arms, or scaling systems, rigid chains have a reduced overall size in the folded state and allow for a long unfolding stroke.

[0005] For example, rigid chain machinery is used in the entertainment industry for high-speed, long-stroke movement of scenery or stage components. This type of machinery can also be used in the manufacturing industry, such as for mass production lines.

[0006] The operating stroke of a rigid chain can be adapted to the operating environment by changing the number of links in the chain.

[0007] The applicant has determined that it needs a pusher chain with high power, low noise and vibration, longer service life and low maintenance.

[0008] This invention improves upon the present situation. Summary of the Invention

[0009] The applicant provides a chain pusher device comprising: a chain pusher including a curved portion and a straight portion along an axis; a chain pusher guide; and a drive sprocket having teeth that mesh with the chain and contacting the chain via an involute contact surface, the contact surface being the teeth, the teeth meshing with the chain by defining a line of action having an angle between -10° and 10°, particularly close to 0°, with respect to the axis of the straight portion. The chain includes links hinged on the axis. The line of action is offset from the hinge axis of the links. The drive sprocket contacts the straight portion and not the curved portion. The drive sprocket is rotatably mounted on an axis located on the side of the chain opposite to the center of curvature of the curved portion. The contact surface of each tooth includes: a convex front surface facing the straight portion when the teeth are engaged and a convex-concave rear surface facing the curved portion when the teeth are engaged. The convex front surface occupies an angle greater than half the angle occupied by the tooth. Along the axis of the straight portion, the sprocket shaft is disposed in a region between the boundary between the curved portion and the straight portion and a maximum distance from said boundary. The teeth exert a thrust on the sprocket at an angle ε. The angle σ from one tooth to the next is equal to 360° / n, where n is the number of teeth on the sprocket, and the difference between ε and σ is greater than 30°.

[0010] The sum of the angle 'a' occupied by the tooth and the angle 'b' occupied by the rounded base separating the tooth equals 360°. Therefore, a + b = 360° / n, where n is the number of teeth. For prior art sprockets, the contact between the teeth and the chain occurs at an angle equal to a / 2 via the chain rollers. This angle is equal to 1 / 2((360° / n) - b). For the sprocket of the present invention, the contact between the teeth and the chain occurs at an angle greater than a / 2 via the chain rollers. This angle can exceed the value of a, but is generally kept less than or equal to a. In other words, the angular position of the free end of the contact surface of the tooth can be behind the tangent between the bottom and back face of the tooth, and is generally kept in front of the angular position at the center of the bottom face.

[0011] When the teeth push the roller in the push chain clockwise, the linear velocity V of the roller along the Z-axis is constant. At the contact point, which is part of the contact surface, V = W. p ×R i , where R i W is the instantaneous radius or distance between the contact point and the rotation axis of the sprocket. p Let R be the instantaneous angular velocity at the point of contact. As R increases and W decreases, the angular velocity of the sprocket remains constant. This is achieved through the involute tooth profile of the front surface or the leading edge of the teeth forming the contact surface.

[0012] Such a device results in advantages for lifting variable loads. Wear is reduced. The asymmetry of each tooth corresponds to the asymmetry of the roller trajectories of adjacent rows of rollers on either side of a plane passing through the axis of rotation of the sprocket and perpendicular to the straight portion of the push chain (i.e., towards and opposite the curved portion). In the straight portion, the distance between the axes of the two consecutive rollers is constant. In the curved portion, the distance between the axes of the two consecutive rollers is variable. This distance increases away from the sprocket, reaches a maximum, and then decreases towards the magazine portion. The increase in this distance in the half of the curved portion adjacent to the sprocket in the direction away from the sprocket allows the teeth and rollers in the curved portion of the push chain to disengage while maintaining distance between them.

[0013] This transmission assembly allows the chain to withstand forces distributed across several teeth and at the point where the chain is guided. Apart from the component of force in the translational direction of the chain, the component of force transmitted to adjacent links is negligible. The energy efficiency of the transmission is significantly higher than previously known. For the same number of sprocket teeth, the sprocket can transmit greater force to the chain. In other words, for the same pitch circle diameter, the sprocket can receive greater torque from the engine. The load on the chain can be increased. Compared to known systems, vibration, wear, and noise during operation are significantly reduced.

[0014] The sprocket engages with the pusher bar. The bar is arranged in two rows, one on the inside of the bend and the other on the outside. Thus, the pitch change of the pusher bar on the bend releases the sprocket teeth.

[0015] In one embodiment, the diameter of the inner rod is reduced by, for example, at least 20% relative to the diameter of the outer rod. This increases the space available for the sprocket teeth.

[0016] In one exemplary embodiment, the diameter of the inner rod is variable along the axis of the rod, for example, a large diameter at the link plate and a small diameter at the center facing away from the sprocket teeth.

[0017] In one implementation, the gap between the rows of rods is increased to increase the length of the sprocket teeth.

[0018] The increase in tooth length is radial and involute. The increase in radial tooth length allows for an increase in the angle occupied by the leading edge of the tooth. It can be increased from a / 2 angle to 2a / 3 or even 3a / 4 angle, or even a, meaning the leading edge occupies at least the angle of each tooth. This significant increase reduces the load supported by each tooth for the same number of teeth.

[0019] In one embodiment, the contact surface is a rolling surface.

[0020] In one embodiment, the contact surface is a sliding surface.

[0021] In one implementation, the drive sprocket is a single sprocket. The drive sprocket may include one or more rows of teeth.

[0022] In one implementation, the drive sprocket is mounted on the same shaft.

[0023] In one implementation, the difference between ε and σ is greater than 34°, more preferably greater than 40°.

[0024] In one implementation, for a sprocket with up to 12 teeth, the difference in ε-σ is greater than 46°.

[0025] In one implementation, for a sprocket with up to 6 teeth, the difference in ε-σ is greater than 49°.

[0026] In one embodiment, the radial dimension of the teeth is selected such that at least two front surfaces of the drive sprocket simultaneously contact the push chain at an angle, wherein the angle is at least 200° for a 5-tooth sprocket; at least 250° for a 6-tooth sprocket; at least 300° for a 7-tooth sprocket; and at least 340° for an 8-tooth sprocket. In another embodiment, the radial dimension of the teeth is selected such that at least three front surfaces of the drive sprocket (1) simultaneously contact the push chain (10) at an angle, wherein the angle is at least 20° for a 9-tooth sprocket; at least 60° for a 10- or 11-tooth sprocket; at least 140° for a 12-tooth sprocket; at least 180° for a 13- to 15-tooth sprocket; at least 260° for a 16- to 24-tooth sprocket; and at least 360° for a 25- to 48-tooth sprocket.

[0027] In one embodiment, the sprocket includes straight teeth comprising 5 to 30 teeth. This number of teeth ensures good continuity of motion between the wheel and the chain, avoids uncontrolled movement when transferring from one tooth to another, and limits vibration and associated noise.

[0028] In one embodiment, the sprocket includes straight teeth with a module between 3 and 64 mm.

[0029] In one embodiment, the push chain includes a chain link and a shaft for mounting the chain link, the shaft being in contact with teeth, at least two of the drive sprocket teeth being in contact with the shaft of the straight portion, the sprocket having at least 8 or even 9 teeth, and the shaft of the straight portion and the shaft of the curved portion being in adjacent rows and columns.

[0030] In one embodiment, the chain comprises links hinged to each other via rods. The rods are freely mounted on the chain links. Rolling between the wheel and the rod is more advantageous than friction, reducing wear on the transmission components during use.

[0031] In one embodiment, the shaft of the drive sprocket is arranged along the shaft of the straight section between the lower end of the straight section and the lower end of the straight section with an increased push chain link length, preferably between the lower end of the straight section and the lower end of the straight section with an increased push chain link length of 150%.

[0032] In one embodiment, the pusher guide is arranged on the side of the pusher chain opposite to the drive sprocket.

[0033] In one embodiment, the guide has a straight push chain guide surface.

[0034] In one implementation, an additional guide is provided outside the curved portion.

[0035] In one embodiment, the front surface of the convex tooth is not flat, and each tooth has a tip and a radial axis, the tip being angled off from the axis toward the curved portion.

[0036] In one embodiment, the force exerted by one tooth on the push chain is transmitted to the next tooth over a sprocket rotation stroke greater than a / 2, preferably at least 3a / 8, more preferably at least a. The force exerted by one tooth on the push chain is transmitted to the next tooth over at least the following drive sprocket rotation strokes:

[0037] For a 6-tooth sprocket, each rotation is 40°;

[0038] For a 12-tooth sprocket, each rotation is 25°.

[0039] For a 24-tooth sprocket, each rotation is 16°;

[0040] For a 48-tooth sprocket, each rotation is 12°.

[0041] In one embodiment, at least one rod includes a substantially cylindrical body and at least one ring that rotates freely around the body to form a guide and / or drive roller for the chain. The roller then acts as a wear part, which can be quickly and easily replaced during maintenance operations without completely disassembling the chain, thereby reducing maintenance costs.

[0042] In one implementation, the sprocket's axis of rotation is horizontal during operation.

[0043] In one implementation, the thrust section is straight.

[0044] The guide may include a contact surface made of synthetic material.

[0045] In one embodiment, the drive sprocket has a linear load capacity between 80 mm and 600 mm, or even 1000 mm. Compared to known sprockets, sprockets with 5 or 6 teeth have a linear load capacity gain of greater than 60%, sprockets with 7 to 12 teeth have a linear load capacity gain of greater than 53%, sprockets with 13 to 24 teeth have a linear load capacity gain of greater than 47%, and sprockets with 25 to 48 teeth have a linear load capacity gain of greater than 45%.

[0046] In one implementation, specifically for 48 teeth, the angle occupied by the front side of the drive sprocket teeth is... Greater than 5 degrees; specifically for 24 teeth, preferably greater than 11 degrees; specifically for 12 teeth, more preferably greater than 23 degrees; specifically for 6 teeth, more preferably greater than 47 degrees.

[0047] In one implementation, the drive sprocket has a sprocket height positioning H between 0 and 1.5 pitch.

[0048] In one embodiment, the flange width Lj of the drive sprocket is between 30 mm and 150 mm, preferably between 40 mm and 120 mm. Attached Figure Description

[0049] Other features, details, and advantages of the invention will become clear from the following detailed description and accompanying drawings, wherein:

[0050] Figure 1 This is a side view of a rigid chain device with a 6-tooth sprocket according to one aspect of the present invention, and also shows the shape of a conventional sprocket for illustrative purposes;

[0051] Figure 2 They are located at different sprocket angles. Figure 1 Detailed view;

[0052] Figure 3 It is a side view of a rigid chain device with a sprocket whose leading edge occupies the first additional angle;

[0053] Figure 4 This is a side view of the sprocket with its leading edge occupying the second additional angle;

[0054] Figure 5 This is a side view of a sprocket with one tooth separated to display dimensional parameters;

[0055] Figure 6 This is a side view of the sprocket, showing the linear load capacity of the teeth and several consecutive positions of the teeth;

[0056] Figure 7 This is a side view of a rigid chain assembly with sprockets, showing the pitch and height, and the chain flange width is greater than... Figure 3 The width of the chain flange in the middle; and

[0057] Figure 8 This is a side view of a rigid chain assembly with a 9-tooth sprocket. Detailed Implementation

[0058] The following figures and descriptions contain largely deterministic elements. Therefore, they are intended not only to enhance understanding of the invention, but also, where appropriate, to aid in its definition.

[0059] The shape of a sprocket engaging with a chain differs significantly from that of two gears engaging together. The chain has cylindrical rods that rotate in contact with the sprocket teeth. These rods are freely mounted to rotate in contact with the sprocket. The diameter of the rods and the distance between the axes of two consecutive rods are chain parameters that affect the sprocket. The characteristics of a sprocket specifically lie in the number of teeth, their diameter, the opening between two adjacent teeth, and the thrust angle. FR2780472 describes a chain pusher drive comprising a sprocket with rollers freely mounted between two toothed flanges, one roller for each sprocket tooth. The chain is free in its bent portions. The thrust is applied to the chain axis in a direction away from the direction of chain translation.

[0060] The applicant seeks to reduce noise, vibration, and wear. Achieving this goal makes it possible to expand the use of push chains to areas where other technologies, such as cables or belts, were previously used.

[0061] Therefore, in addition to making gradual improvements, the applicant also sought to understand the limitations of the current mechanism. Starting with the sprocket and chain configuration shown in FR3061753, good alignment between the line of action and the axis of the straight section is beneficial. By maintaining this characteristic, it was found that the symmetry of each tooth about the plane passing through the axis of rotation is used to ensure no geometric interference between the tooth and the chain, and is also necessary to achieve the required transmission contact. Therefore, there is no interference between the tooth after engagement and the next roller in the chain, and they gradually approach each other to contact, then engage sequentially.

[0062] At this stage, the applicant conducted an extensive analysis of the vibration phenomenon and determined that a significant portion of the vibration occurs during the period of sudden deviation in the sprocket profile when the load supported by the chain is transferred to the next tooth. Therefore, a longer contact time was sought so that the sprocket could be supported simultaneously by several teeth, thereby distributing the load. To this end, increasing the sprocket pitch circle diameter and the number of sprocket teeth was considered, but this would mean an increase in the overall size of the sprocket, an increase in the sprocket's drive torque under the same load, and changes to the engine system.

[0063] The applicant then sought a method to maintain the pitch circle diameter and the number of teeth of the sprocket. The sprocket teeth were designed to be extended to allow for asymmetry in tooth profile and to change the sprocket's position in the direction of the top surface of the curved section. Extending the teeth caused interference problems with rollers adjacent to the meshing rollers. Making the teeth asymmetrical also caused interference problems. Changing the sprocket's positioning towards the top surface of the curved section tended to reduce the stroke during the period of operable roller-tooth contact. The applicant recognized the need to guide the chain flange in a straight line in its vertical section while applying thrust through the sprocket teeth. The curved section is guided by the sprocket teeth without thrust. It is necessary to avoid transmitting force to the guide of the curved section.

[0064] During the research, the applicant realized that there were areas where sprockets were positioned in an interesting way. As the shaft of a preceding sprocket with the same number of teeth and the same pitch diameter, and mating with a chain and rollers of the same diameter, the sprocket's shaft was located at the same axial distance from the straight portion of the chain. Pitch is the axial distance between two roller shafts of the chain, specifically between the two roller shafts along the straight portion of the chain on the side closest to the sprocket.

[0065] In FR3061753, the lowest contact point between the tooth and the roller is also located at a certain distance from the curved portion. In practice, this contact point is located above the curved portion. According to the invention, the shaft of the sprocket 1 is positioned along the axis of the straight portion 10a of the chain at a short distance from the curved portion 10b. The lowest contact point between the tooth 2 and the roller 171 is far from the curved portion 10b. The lowest contact point between the tooth 2 and the roller 171 is above the curved portion 10b, see details below. Figure 7 .

[0066] According to the invention, the shaft of the sprocket 1 is positioned along the axis of the straight portion 10a of the chain 10 between the boundary 30 separating the curved portion 10b and the straight portion 10a and a distance greater than half the pitch from the boundary 30 relative to the curved portion 10b. This distance can be greater than 0 to one and a half pitches. An orthogonal reference frame XYZ is defined, with the X-axis parallel to the rotation axis of the sprocket 1, the Z-axis being the translation axis of the straight portion 10a, and the Y-axis perpendicular to both the X and Z axes. In most cases, the X and Y axes are horizontal, and the Z-axis is vertical. In other words, the shaft of the sprocket 1 is arranged in the region between the boundary 30 separating the curved portion 10b and the straight portion 10a and the maximum distance from the boundary 30, where the maximum distance is greater than 0, less than or equal to 1.5 pitches, and preferably equal to half a pitch.

[0067] The distance allows the front side 2a of tooth 2 or the load side of tooth 2 to support the roller 171 located above the shaft of sprocket 1 on a higher angular path. The distance also allows the roller 171 located in the curved portion 10b to approach the front side 2a of tooth 2 in the clockwise rotational direction of sprocket 1 corresponding to the chain rise in the figure, without interfering with the tip of the previous tooth 2 on the rear side 2b or its front side 2a, which has already engaged with the previous roller 171. In the counterclockwise direction, the roller 171 escapes in the direction opposite to tooth 2. In other words, according to the invention, the roller 171 has a non-zero velocity along the Y-axis in a direction opposite to the velocity component along the Y-axis of the corresponding tooth 2, instead of having a zero component along the Y-axis as in the prior art, where the roller 171 continues to travel along the straight portion 10a. The front side 2a has a convex shape. The curvature of the front side 2a is chosen to avoid variations in chain speed and engine torque. The rear side 2b has a concave shape (partially concave and partially straight or partially concave and partially convex). The rear side 2b may have a shape symmetrical to the front side 2a near the base of tooth 2 and a partially concave shape away from the base of tooth 2. In another embodiment, such as Figure 4 and Figure 7 As shown, the shape of the rear side 2b is symmetrical to the front side 2a portion away from the end of tooth 2, and the portion near the end of tooth 2 is concave. The front side 2a or the convex front surface occupies an angle greater than half the angle occupied by tooth 2. The front side can occupy an angle greater than 5 degrees, especially for 48 teeth. The front side can occupy an angle greater than 11 degrees, especially for 24 teeth. The front side can occupy an angle greater than 23 degrees, especially for 12 teeth. The guiding side can occupy an angle greater than 47 degrees, especially for 6 teeth.

[0068] The front side 2a faces the straight portion 10a. The rear side 2b faces the curved portion 10b. The sprocket 1 is capable of operating under compression and traction.

[0069] The transmission element or curved portion 10b, along the Y-axis, near the sprocket 1, utilizes the openings in the chain links to space the rollers 171 apart, allowing the passage of the long tooth 2 between two consecutive rollers 171. The tooth 2 is long because it is longer radially than the teeth of a known chain sprocket, both inwardly and through its front side 2a. The overall dimensions of the winding distance and angle of the front side 2a are increased. The front side 2a extends at an angle greater than half the angular dimension of the tooth 2. For a 6-tooth sprocket, the front side 2a extends more than 30° or even more than 60°, preferably between 40° and 55°. For a 5-tooth sprocket, the front side 2a extends more than 36° or even more than 72°, preferably between 50° and 65°. For a 7-tooth sprocket, the front side 2a extends more than 25° or even more than 51°, preferably between 30° and 45°. For an 8-tooth sprocket, the front side 2a extends more than 22.5° or even more than 45°, preferably between 28° and 40°.

[0070] Therefore, in the clockwise rotation direction of sprocket 1, at the same rotational speed, tooth 2 remains under the load of the roller for a longer angular path and a longer time period. The contact loss between tooth 2 and the corresponding roller 171 is farther from the starting point of the front side 2a of the next tooth 2. By analogy to sprocket 1 with n teeth, each tooth 2 occupies an angle of 360° / nb. In the simple assumption that the front side 2a of each tooth 2 occupies 75% of the angle a occupied by tooth 2, the front side 2a extends angularly by 50%. If the front side 2a occupies 100% of the angle a occupied by tooth 2, then the front side 2a extends angularly by 100% compared to the symmetrical tooth. The increase in the angular path during the roller driven by tooth 2 enables simultaneous support of two teeth on two consecutive teeth and provides a smooth transition between zero and maximum support for the incoming tooth 2 and between maximum and zero support for the outgoing tooth 2.

[0071] This transition can be provided over an angular region of several degrees. The angular region of the transition can be between 1°, preferably 5°, and an extension of 2a above the front side, i.e., a / 4 for 50% extension. The meshing becomes smoother and gentler. The acceleration of the vibration peak is reduced by at least 10% to 30%, the velocity by at least 10% to 30%, and the displacement by at least 60% to 90%, depending on the upward and downward operating modes and the speed. In terms of vibration, the sprocket 1 according to the invention performs similarly to that of a sprocket with one or two teeth, while maintaining the same torque required for an engine with a sprocket with six teeth and for at least two more teeth of a sprocket with 12 or more teeth. Furthermore, due to the wear on the chain and sprocket surfaces caused by vibration, the abrasion of the contact surfaces is reduced, thereby extending the service life.

[0072] The pusher mechanism includes an open pusher. "Open" here means a chain with separate ends. The chain includes a straight or pushing portion 10a, a magazine portion 10c, and a drive or curved portion 10b between the pushing portion 10a and the magazine portion 10c. The mechanism includes a pusher guide 20 on the curved portion 10b. The straight portion is typically vertical and is guided to withstand lateral, typically horizontal, forces. The mechanism includes a drive sprocket 1 with teeth 2 that mesh with the pusher in the straight portion 10a. The sprocket 1 includes one or more rows of teeth 2. Rows include teeth 2 located in the same plane. The mechanism includes a storage space for the magazine portion 10c. The storage space may be parallel to the straight portion 10a and located opposite the center of curvature of the curved portion 10b to the straight portion 10a.

[0073] Under compression, and optionally under tension, the drive sprocket 1 engages with the push chain on the side opposite to the storage section 10c. The drive sprocket 1 contacts the push chain via an involute surface belonging to teeth 2, which engage with the chain by defining a line of action having an angle between -10° and 10°, preferably around 0°, with respect to the push section.

[0074] Preferably, the angle between the line of action and the thrust portion is between -2° and 2°, more preferably between -1° and 1°. The force borne by the guide 20 is as low as a first approximation defined by the sine of the aforementioned angle, i.e., less than 3.5% of the chain thrust. The contact surface provides low friction and negligible chain wear, while it itself undergoes wear compatible with interval maintenance visits.

[0075] As shown in the figure, a toothed sprocket 1 is rotatably mounted about an axis parallel to the X-axis. A circular engagement surface 100 belonging to the chain 10 is translatably mounted along the Z-axis. Here, the term "axis" is used in its geometric sense. In the above embodiment, the circular engagement surface 100 corresponds to the circular shape of the rod 11 as seen in the side view. The X-axis corresponds to the main direction of the drive shaft or sprocket shaft. The Z-axis corresponds to the vertical direction of movement along the circular engagement surface 100 carried by the rod 11.

[0076] Pointing to C from the center n-1 C n and C n+1i The circular meshing surface 100, represented by the circle, is directly supported by the body of the rod 11 without a ring, or by an intermediate component, such as a roller, which is supported by the body of the rod 11 and forms a drive roller.

[0077] The rotation axis of sprocket 1 and the translation axis of circular meshing surface 100 are orthogonal and are separated from each other by a distance equal to the pitch circle radius Rp.

[0078] During the meshing motion, at least two teeth 2 of the sprocket 1 contact the circular meshing surface 100. Since the teeth 2 are spurs and the circular meshing surface 100 can move orthogonally to the X-axis, contact is established along a line extending along the X-axis. As seen in the plane figure, the contact can therefore be represented by the contact point marked M. This connection is a straight-line connection.

[0079] In mechanics, one of the most common applications of motion transmission is the conversion of one rotational motion into another. Known transmissions involve a first toothed sprocket with spur teeth and a second toothed sprocket with spur teeth meshing together to form a spur gear to convert the first rotation into the second. In the literature, this simple gear type serves as a reference for defining other gear types. By analogy, some technical terms will be used to describe push-chain gears.

[0080] In this case, the component converts rotational motion about the X-axis into translational motion along the Z-axis. In this respect, the device is similar to a rack and sprocket. However, the circular meshing surface 100 differs in shape from that of a conventional rack. Therefore, the meshing between the shape of the tooth 2 on one hand and the circular meshing surface 100 on the other hand provides the device's gears with meshing characteristics different from those of racks and sprockets. Here, the lever 11 performs two different functions, namely:

[0081] - The circular meshing surface 100 that forms or carries the teeth 2 of the contact sprocket 1, and

[0082] - Ensure a good connection between the two plates 121 of the same link, and thus ensure good stability of the chain.

[0083] The sprocket 1 meshes with the straight, vertical portion of the chain. Therefore, the movement of the lever 11 during meshing is a combination of upper translation and lower rotation. This complex translational and rotational motion distinguishes the gears of the chain 10 from conventional systems that include closed chains with curved portions wound around toothed pulleys, such as traction chain systems or bicycle drive systems, and push chains where only the straight portion meshes with the sprocket. The sprocket 1 meshes on the surfaces of the straight portion 10a and the curved portion 10b, opposite the center of curvature of the curved portion 10b. The storage portion 10c is arranged in the storage space.

[0084] In summary, the meshing of chain 10 cannot be made similar to that of a conventional rack or roller chain.

[0085] The combination of complex linear and pivotal motions and the circular shape of rod 11 enables the meshing of transmission assembly 1 to have high vibration performance and low amplitude vibration, allowing for high speed, high load, quiet operation, compact drive, or a combination thereof, and is particularly suitable for rigid chain machinery.

[0086] The Z-axis corresponds to the contact line, and the tangential velocity of sprocket 1 along the contact line is equal to the linear velocity of the circular meshing surface 100. Therefore, the pitch circle radius Rp or distance separating the contact line of sprocket 1 from the rotation axis can be equivalent to the pitch circle radius of sprocket 1, which is equal to half the pitch circle diameter Dp. By analogy with racks and sprockets, the contact line can be equivalent to the pitch line of the straight portion 10a of chain 10. The pitch radius of sprocket 1 is the distance between the rotation axis of sprocket 1 and the axis of the roller at the point closest to the rotation axis (i.e., where the roller axis is located in the XY plane passing through the rotation axis). The module m of sprocket 1 is equal to the module m of chain 10. The pitch p of sprocket 1 is equal to the pitch p of chain 10. Pitch p is defined as the length of the arc taken on the pitch circle of sprocket 1 between two points on similar meshing sides of two consecutive teeth 2. The relationship between pitch p and module m is the following equation: p = m * Π.

[0087] During engagement, the meshing side of tooth 2 establishes contact with the circular meshing surface 100. In the side view, the contact between the two convex surfaces is defined by the tangent 181, which is a dashed line. During engagement, the contact point M moves along a theoretical straight line called the line of action, marked 182. Physically, the line of action 182 represents the direction in which force is transmitted from one meshing component to another through the contact point M.

[0088] The line of action 182 is substantially perpendicular to the contact tangent 181. In a conventional two-tooth gear with a conjugate involute tooth profile, the direction of the contact tangent and the center line, i.e., the straight line connecting the centers of the two gears, forms a pressure angle. Therefore, the direction of the line of action and the center line forms a pressure angle ±π / 2.

[0089] In rack and pinion gears with conjugate involute tooth profiles, the rack can be considered as a gear with an infinite radius. The straight line extending in the translational direction of the rack and corresponding to the pitch circle of the infinitely large radius gear is called the reference line or pitch line. In this case, the line of action forms a pressure angle with the reference line. Therefore, the contact tangent forms a pressure angle ±π / 2 with the reference line.

[0090] Compared to the first barrier transmission system, especially Leonardo da Vinci's system, gears with conjugate involute tooth profiles, whether wheel-to-wheel or rack-to-gear, offer superior performance. The first property is that the transmission is essentially of equal kinetic energy: if the speed of one gear component is constant, then the speed of the other component is also constant. The second property is that during meshing, the pressure angle remains essentially constant within machining tolerances and the phenomena of contact initiation and termination. The third property is that it promotes rolling contact between two convex surfaces without slippage. Therefore, the transmission of motion is continuous and uniform. Furthermore, friction and wear are finite.

[0091] To withstand large forces and avoid embrittlement of the rack, involute teeth are generally truncated. In other words, the radial end of each tooth is clamped, and the tooth gullet (between two teeth) is not machined to the tooth gullet. Therefore, the radial ends of the teeth are essentially flat or rounded, rather than pointed, and for the same reason, the tooth gullet has a substantially corresponding parent shape. These adaptations of the conjugate involute tooth profile also limit certain slip phenomena. On the other hand, operational disturbances occurring at the beginning and end of contact between two conjugate teeth, also known as the approach and exit phases, are addressed in known mechanisms by lowering the sprocket 1, causing the approach phase to occur in the curved portion 10b of the chain 10. This lowering limits the clamping of the tooth 2.

[0092] The value of the pressure angle is usually set according to a standard. For example, the nominal value is 20° according to European standards and 25° according to American standards. Some gears, especially older gears, are specifically allowed a value of 14.5°. Setting a standard value also allows gear components, such as wheels and racks, to be manufactured (machined) with a single tool. In other words, designing a gear with a pressure angle different from the standard pressure angle would mean designing a special machining tool, which is both complex and expensive. Finally, gear design is generally done using charts related to a large number of parameters such as the number of teeth and the module. These charts are built on the basis of the standard pressure angle. It is generally not recommended for technicians to deviate from this.

[0093] In this implementation, the teeth 2 of the sprocket 1 are operatively engaged with the rod 11, which has a circular meshing shape. This avoids certain slippage and operational interference phenomena, including during the approach and disengagement phases.

[0094] The sprocket 1 contains, for example, 5 to 30 teeth 2. In the example, the sprocket 1 is shaped as a six-tooth gear 2. The shape of the sprocket 1 is similar to that of a gear having an involute tooth profile conjugate to a rack with a pitch p. The teeth 2 have a front side 2a and a rear side 2b. The concepts of front and rear sides relate to the force applied between the sprocket 1 and the chain 10. The teeth 2 are essentially pointed. The pitch circle radius Rp of the sprocket 1 is adjusted so that the pressure angle at the point of contact is essentially zero. Here, the pitch circle radius Rp is less than the distance corresponding to a standard pressure angle of 20° or 25°. The value of the pitch circle radius Rp is selected based on the dimensions of the components, particularly the diameter of the rod 11 and the pitch p. For example, the pitch p is between 10 and 200 mm. The module m is between 10 / π and 200 / π mm, i.e., between approximately 3 and 64 mm. Furthermore, R is the radius of the curved portion 10b, rg is the radius of the roller 171, and D is the diameter of the circle whose center is the axis of rotation of the roller 171 in the column opposite to the sprocket 1 and passes through the axis of rotation of the adjacent roller 171 in the column near the sprocket 1.

[0095] The table below lists some examples of pitch circle radius values ​​Rp in millimeters, which are functions of the pitch p in millimeters in the left column and the number of teeth n indicated in the first row.

[0096] [Table 1]

[0097] Number of teeth 5 6 8 9 10 12 15 p = 20mm 15.915 19.099 25.465 28.648 31.831 38.197 47.746 p = 30mm 23.873 28.648 38.197 42.972 47.746 57.296 71.620 p = 40mm 31.831 38.197 50.930 57.296 63.662 76.394 95.493 p = 50mm 39.789 47.746 63.662 71.620 79.577 95.493 119.366 p = 60mm 47.746 57.296 76.394 85.944 95.493 114.592 143.239 p = 80mm 63.662 76.394 101.859 114.592 127.324 152.789 190.986 p = 90mm 71.620 85.944 114.592 128.916 143.239 171.887 214.859 P = 100mm 79.577 95.493 127.324 143.239 159.155 190.986 238.732

[0098] The combinations of values ​​provided are exemplary embodiments of the present invention. They correspond to pressure angles with absolute values ​​close to zero.

[0099] The gear shown includes teeth 2 of sprocket 1 and a conjugate circular meshing surface 100, thus having a pressure angle α that is essentially zero. In other words, the line of action forms an angle of essentially zero with the translational direction of the thrust portion 10a of chain 10. The line of action is essentially parallel to the Z-axis. The contact tangent forms a substantially right angle (pressure angle ±π / 2) with the translational direction of the thrust portion 10a of chain 10. In practice, considering machining tolerances, the absolute value of the angle is less than 5°.

[0100] Alternatively, the absolute value of the pressure angle may be lower than the aforementioned standard value, but greater than 0. For example, the pressure angle may be between -10° and 10°, or between -5° and 5°, or between -2° and 2°, or between -1° and 1°. Then, the contact tangent 181 and the translational direction of the thrust portion 10a of the chain 10 form angles (α ± π / 2) between 80° and 100°, 85° and 95°, 88° and 92°, and 89° and 91°, respectively.

[0101] In the example shown, the space between the circular meshing surfaces 100 supported by the rod 11 is free. There is no "bottom" connection between one outer rod 11 and the other rod. The movement of the teeth 2 of the sprocket 1 is free during the meshing motion.

[0102] Here, the radial end of tooth 2 is theoretically pointed, but is machined with a rounded corner in production. The radial end of tooth 2 is not clamped. According to the invention, as Figure 1 As can be seen, there is a search for achieving several simultaneous contacts, preferably one or two more than the single contact sought in the prior art, to reduce vibration and the resulting noise. Furthermore, when contact point M... n+1 Approaching tooth 2 n+1 At the end (at the top of the attached diagram), in the next tooth 2 n 100 and circular meshing surface n A new contact point M has been established between them. n And so on. Although in practice the angular region of tooth 2 is usually the boundary that favors the design of tooth 2, the leading edge also occupies a significant angular region greater than half of the angular region of tooth 2, and theoretically can extend beyond the angular region of tooth 2. Therefore, when the contact point M n+1 Approaching tooth 2 n+1 When half of the angular region is reached, at the next tooth 2 n / Circular meshing surface 100 n A new contact point Mn is formed between the pairs, and so on. The force is shared and gradually transferred to the new pairs 2n / 100n, thereby reducing the derivative of the force at the contact point M, and thus reducing vibration.

[0103] In the example shown, the intertooth grooves of the teeth 2 of the sprocket 1 are machined into a basic circular profile with a diameter equal to or greater than the diameter of the circular meshing surface 100. Thus, within machining tolerances, each circular meshing surface 100 is positioned within the intertooth groove between the two teeth 2 before being driven by the downstream tooth 2.

[0104] In the example described here, the rod 11 is freely mounted relative to the link 12 of chain 10. Therefore, during engagement, it facilitates the rolling of the outer rod 11 against the meshing surface of the tooth 2, reducing friction. Similar to the wear of the tooth 2, the wear of the rod 11 is also reduced. Alternatively, the rod 11 is fixedly mounted between one of the two links 12 to which it is connected. In this case, slippage occurs during engagement when directly contacting the rotationally locked circular meshing surface 100. Therefore, despite this, the manufacture of chain 10 can be facilitated. For example, the link 12 and the outer rod 11 can be integrally formed or welded together.

[0105] The device described so far can generate very little radial force in the gears. The radial force is essentially directed in the Y direction. This further stabilizes the chain 10 during chain movement and prevents vibrations transmitted from the sprocket 1 to the chain 10, especially when performing high-speed movements.

[0106] The general operating principles, especially the kinematics of the machine, are described in FR2786476, which readers are advised to consult.

[0107] Chain 10 includes links 12. Links 12 are hinged to each other to form chain 10. Chain 10, in conjunction with the device, forms a motion transmission component. Hereinafter, the chain 10 is referred to from the tail link 121 carrying the hook plate to the head link 12. N Let's index link 12 from 1 to N. Index n refers to link 12. n or link 12 n This refers to the part of the chain. In this context, the term "chain link" will be understood as the basic mechanical model of equivalent replication along chain 10. Chain link 12 n One side is connected to link 12 n-1 And on the other hand, it is connected to link 12 n+1 , of which 1 <n<N。

[0108] When rising, that is, when sprocket 1 rotates clockwise, link 12 n The storage portion 10c, the curved portion 10b, and the straight portion 10a belong to chain 10 in sequence, and the same applies when descending.

[0109] The device also includes a fixed guide 20. The guide 20 forms a rolling surface for the guide roller 171 described below. The guide 20 may include portions forming the rolling surface made of a low-abrasion material. The guide 20 has a first straight portion corresponding to the straight portion 10a, a second straight portion corresponding to the storage portion 10c, and a curved portion 10b corresponding to the curved portion 10b. The guide 20 provides an outward-facing rolling surface, and the curved portion 10b is convex. One end of the curved portion 10b smoothly connects to the first straight portion, and the other end smoothly connects to the second straight portion; in other words, there is no singularity of derivative. The curved portion 10b forms a transmission component. In the illustrated embodiment, the curved portion 10b is a semicircle with a constant radius.

[0110] When sprocket 1 rotates counterclockwise, chain 10 is pushed toward the storage by each tooth 2 in contact with chain 10. When sprocket 1 rotates clockwise, chain 10 is pushed upward by each tooth 2 and out of storage. Contact is established at the start of engagement and remains at the end of engagement, loading the straight section 10a.

[0111] Chain 10 may be of the type described in FR2780472, for the reader's reference.

[0112] Chain 10 comprises a plurality of consecutive links 12. These links 12 are hinged around a rod 11 forming a transverse axis. Each link 12 includes two substantially parallel flanges or pairs of parallel plates 121. Each plate 121 has three through holes for receiving a hinge shaft and two notches forming half-holes. Each plate 121 defines a front transverse movement surface and a rear transverse movement surface, such that when the links 12 are in a straight line, particularly within the straight portion 10a of chain 10, they are supported on the rear transverse movement surface of the front link plate 121 and the front transverse movement surface of the rear link plate 121, respectively. Each plate 121 is arranged in the YZ plane. One plate 121 is disposed within the link, and another plate 121 is mounted outside the link, they being symmetrical with respect to the YZ plane. The inner plate 121 of the same link adjacent to the outer plate 121 is hinged to a common rod 11. The inner plate 121 of an adjacent link adjacent to the outer plate 121 is hinged to another common rod 11. The common rod is located on the side opposite to the sprocket 1. On this side of the sprocket 1, each rod 11 is connected to alternating inner and outer plates 121.

[0113] Each end of the shaft or hinge rod of link 12 is provided with a guide roller 171. The guide roller 171 is located outside plate 121. The guide roller 171 mates with a side guide rail provided on the side flange of the housing, forming a guide portion in the thrust and storage section, and mates with an offset member in the connection section.

[0114] To improve readability, the outline of the conventional tooth 200 is also shown in the accompanying drawings. Figure 3In this design, the shape of tooth 2 is extended to what is called the outer radius, corresponding to the theoretical maximum radius at the intersection of the front side 2a and the rear side 2b. The maximum radius is equal to the distance between the rotation axis of sprocket 1 and the outer surface of roller 171 in the row of rollers opposite sprocket 1. If the maximum radius is greater than this distance, interference will occur between tooth 2 and roller 171 in the row of rollers opposite sprocket 1. In practice, a safety margin is adopted. The actual radius of sprocket 1 is chosen to be a distance F a few millimeters smaller than the maximum radius. Figure 1 and Figure 2 As shown, this avoids the acute angle between the front side 2a and the rear side 2b, which is dangerous to the operator, and rounds the end of the tooth 2. Another way to avoid this interference is to mount the rotation axis of the sprocket 1 closer to the boundary plane 30 between the straight portion 10a and the curved portion 10b. Figure 3 It is understood that the winding length of the front side 2a can be greater than 70% of the pitch circle radius, preferably 95%, and more preferably 130%.

[0115] In one implementation, the front side 2a with the involute tooth profile stops at the intersection of the shaft and the center of the concave fillet of the next tooth 2. This avoids geometric overlap of tooth 2 on the next tooth. However, such overlap is possible as an alternative by changing the dimensions of the chain flange along the Z-axis.

[0116] In practice, the maximum diameter Dmax of the sprocket of the present invention with n teeth and chain pitch p is equal to the Dmax of the standard symmetrical sprocket with n / 2 teeth and chain pitch 2p.

[0117] Therefore, the length of the involute tooth profile of the tooth 2 of the sprocket 1 of the present invention having n teeth is equal to the length of the involute tooth profile of the symmetrical tooth of a known sprocket having n / 2 teeth and a chain pitch of 2p.

[0118] The tooth bearing capacity 2 of the sprocket 1 of the present invention is the same as that of a tooth with twice the pitch, but its pitch diameter is divided by 2.

[0119] In order to understand Figures 4 to 7 Name the following variables:

[0120]

[0121] The table below compares the triangular variables obtained from the above formula for the meshing sprocket 1 of the present invention and a conventional sprocket. The pitch p, number of teeth n, and radius Rci of the intermediate circle between two teeth are input parameters. The pitch circle diameter Dp and the increment Delta PI of the linear load capacity PI for the meshing sprocket 1 of the present invention and the conventional sprocket are calculated based on the input parameters. Distances are expressed in mm.

[0122]

[0123]

[0124]

[0125]

[0126]

[0127] Increased load-bearing capacity

[0128] The above results clearly demonstrate that the load-bearing capacity of the teeth 2 of the sprocket 1 of the present invention is greater than that of conventional sprocket teeth, thereby allowing for greater diversity in the simultaneous contact between the teeth 2 of the sprocket 1 and the roller 171 of the push chain 10, while avoiding an increase in the number of teeth 2 of the sprocket 1, and thus avoiding an increase in its pitch circle diameter.

[0129] exist Figure 4 In the middle, the teeth 2 have been extended as much as possible while avoiding interference with the inner roller 171. The linear load capacity gain of the front side 2a is at least 60%. The linear load capacity can be between 80mm and 1000mm, particularly greater than 120mm for 12 teeth, preferably greater than 180mm, or even 300mm for 24 teeth.

[0130] exist Figure 6 In the pusher chain 10 with wider-spaced rows of rollers 171, the linear load capacity has been maximized while avoiding interference with the inner rows of rollers 171. The linear load capacity gain of the front side 2a is at least 80%. Increasing the distance between rows of rollers 171 is beneficial for increasing angular load capacity. This can lead to an increase in flange width, resulting in increased inertia and stability. The flange width Lj is between 30 mm and 150 mm, preferably between 40 mm and 120 mm.

[0131] The applicant has identified several parameters reflecting the present invention and allows for quantitative comparisons. The difference in ε-σ reflects the increase in the unit load capacity of the teeth. The ε-σ difference of the sprocket of the present invention is greater than 34°, more preferably greater than 40°. For a sprocket with a maximum of 12 teeth, the ε-σ difference may be greater than 46°. For a sprocket with a maximum of 6 teeth, the ε-σ difference may be greater than 49°.

[0132] exist Figure 7 The height H has been shown, defining the vertical position of sprocket 1 relative to the boundary 30 between the curved section 10b and the straight section 10a. This height is between 0 and one and a half pitches. The height H depends on the definitions of parameters Lj, Dmax, and R, allowing the involute of tooth 2 to pass freely between each roller 171 spaced by a variable pitch Pv, which varies due to the pivoting of the flange in the curved section. The variable pitch Pv is at least... Figure 7It exists within the region enclosed by a slanted rectangle drawn by thin lines. The pitch is constant in the straight section. In the curved section, the pitch increases from the straight section, reaches its maximum at the plateau or peak, and decreases as it approaches the storage section.

[0133] The transmission components can be in the form of modules or component kits. For example, two identical chassis with the same drive can be compatible with storage compartments and / or chains of different lengths. The kit may include several chains or optional chain links that can be added / removed.

[0134] The present invention is not limited to the transmission components and mechanisms described above as examples only, but includes all alternatives that can be conceived by those skilled in the art.

Claims

1. A chain pusher device, comprising: A push chain (10) comprising a curved portion (10b) and a straight portion (10a) along an axis, the chain comprising links (12) hinged to the axis; a guide (20) for the push chain; a drive sprocket (1) having teeth (2) engaging with the push chain, the drive sprocket (1) contacting the push chain via an involute contact surface (2a) belonging to the teeth (2), the teeth (2) engaging with the chain (10) by defining a line of action having an angle between -10° and 10° with the axis of the straight portion (10a), the line of action being offset relative to the hinge axis of the links (12), characterized in that: The drive sprocket (1) contacts the straight portion (10a) but not the curved portion (10b). The drive sprocket (1) is rotatably mounted on a shaft located on the side opposite the center of curvature of the push chain and the curved portion (10b). The contact surface (2a) of each tooth (2) includes a convex front surface facing the straight portion (10a) when the tooth (2) is engaged and a rear surface facing the curved portion when the tooth (2) is engaged. The convex front surface occupies an angle greater than half the angle occupied by the tooth (2). The sprocket shaft is arranged along the axis of the straight portion (10a) in the region between the boundary between the curved portion (10b) and the straight portion (10a) and the maximum distance from the boundary (30). The tooth (2) applies a thrust to the rotation angle ε of the sprocket (1). The angle σ from one tooth to the next tooth is equal to 360° / n, where n is the number of teeth of the sprocket (1). The difference between ε and σ is greater than 30°.

2. The apparatus of claim 1, wherein, The push chain includes a rolling or sliding surface that contacts the tooth (2), the drive sprocket (1) is a single sprocket, or multiple drive sprockets are mounted on the same shaft, and the difference between ε and σ is greater than 34°.

3. The apparatus of claim 2, wherein the difference between ε and σ is greater than 40°.

4. The apparatus of claim 3, wherein for a sprocket having at most 12 teeth, the difference of ε-σ is greater than 46°.

5. The apparatus of claim 3, wherein for a sprocket having at most 6 teeth, the difference of ε-σ is greater than 49°.

6. The apparatus of claim 1, wherein, The radial dimension of the tooth (2) is selected such that at least two front surfaces of the drive sprocket (1) simultaneously contact the push chain (10) at a certain angle. For a 5-tooth sprocket, this angle is at least 200°; for a 6-tooth sprocket, this angle is at least 250°; for a 7-tooth sprocket, this angle is at least 300°; and for an 8-tooth sprocket, this angle is at least 340°. The drive sprocket (1) is positioned such that at least three front surfaces simultaneously contact the push chain (10) at an angle of at least 20° for a 9-tooth sprocket; at least 60° for a 10- or 11-tooth sprocket; at least 140° for a 12-tooth sprocket; at least 180° for a 13- to 15-tooth sprocket; at least 260° for a 16- to 24-tooth sprocket; and at least 360° for a 25- to 48-tooth sprocket.

7. The apparatus of claim 1, wherein, The drive sprocket (1) is a single sprocket, or multiple drive sprockets are mounted on the same shaft.

8. The apparatus of claim 1, wherein, The push chain includes a link and a shaft on which the link is mounted, the shaft contacting the teeth (2), at least two teeth (2) of the drive sprocket (1) contacting the shaft of the straight portion (10a), the sprocket (1) having at least 8 or even 9 teeth, and the shaft of the straight portion (10a) and the shaft of the curved portion (10b) being in adjacent rows and columns.

9. The apparatus of claim 1, wherein, The shaft of the drive sprocket (1) is arranged along the shaft of the straight section (10a) between the lower end of the straight section (10a) and the lower end of the straight section (10a) with the increased link length of the push chain.

10. The apparatus of claim 9, wherein, The shaft of the drive sprocket (1) is arranged along the shaft of the straight section (10a) between the lower end of the straight section and the lower end of the straight section (10a) which has increased the length of the push chain link by 150%.

11. The apparatus of claim 1, wherein, The push chain guide (20) is disposed on the side of the push chain opposite to the drive sprocket (1). The guide (20) has a straight push chain guiding surface and an additional guide is disposed outside the curved portion (10b).

12. The apparatus of claim 1, wherein, The force exerted on the push chain by one of the teeth (2) is transmitted to the next tooth (2) over the rotational stroke of the following drive sprocket (1): at least 40° per revolution for a 6-tooth sprocket, at least 25° per revolution for a 12-tooth sprocket, at least 16° per revolution for a 24-tooth sprocket, and at least 12° per revolution for a 48-tooth sprocket.

13. The apparatus of claim 1, wherein, The front surface of the convex tooth is not flat, each tooth (2) has a round tip and a radial axis, the round tip being angularly offset from the axis toward the curved portion (10b), and the rear surface is convex and concave.

14. The apparatus of claim 1, wherein, The drive sprocket (1) has 5 to 30 involute teeth (2) rotatably mounted around an axis, the chain (10) includes a rod (11), at least one of the rods (11) meshes with the drive sprocket (1), and the drive sprocket (1) includes straight teeth with a module m between 3 mm and 64 mm.

15. The apparatus of claim 1, wherein, The drive sprocket (1) has a linear load capacity between 80 mm and 1000 mm, the leading edge of the tooth occupies an angle (φ) greater than 5 degrees, the height H of the sprocket is positioned between 0 and 1.5 pitches, and the width Lj of the flange is between 40 mm and 120 mm.

16. The apparatus of claim 15, wherein, The leading edge of the tooth of the drive sprocket (1) occupies an angle (φ) greater than 11 degrees.

17. The apparatus of claim 16, wherein, The leading edge of the tooth of the drive sprocket (1) occupies an angle (φ) greater than 23 degrees.

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