Connection system and connection arrangement

Abstract

The present invention relates to a connection system having a first element (20) and a second element (22), wherein the first element (20) and the second element (22) can be inserted into one another for connection to one another. The first element (20) has cutting teeth (26) which cut a corresponding tooth profile (32) into the second element (22) in a cutting direction (34) during insertion. The second element (22) has a chip removal groove (60) which results in a chip being removed from the second element (22) by means of the cutting teeth (26) when an assembly position is reached. The invention also relates to a connection arrangement.

Description

[0001] Connection system and connection arrangement

[0002] The present invention relates to a connection system with which two elements can be connected to each other by means of corresponding toothing, in particular for a bicycle. The invention also relates to a connection arrangement.

[0003] It is known to join two components using a cutting tooth connection. In this process, the two components are pressed together, with one component's cutting toothing engaging the other. However, the resulting chips can hinder the pressing action. For example, a chip can block further pressing, even before the components have reached their desired assembly position. Furthermore, a chip compressed by the pressing action can create a spring effect that pushes the pressed-in component out of its final position.

[0004] From DE 23 47372 AI a positive locking connection of two components is known, in which one of the two components has teeth with cutting surfaces which: when the two components are pressed together, cut a toothing in the other component.

[0005] From DE 102007 000 659 A1, a positive-locking connection of two interlocking components with toothing is known. Guide surfaces are provided to center the two components relative to each other when the connection is made.

[0006] It is therefore an object of the present invention to propose a connection system that is an improvement over the prior art. This object is achieved by the items with the features of the dependent claims. Preferred embodiments are described in the dependent claims.

[0007] A first aspect concerns a connection system with a first element and a second element. The two elements can be, for example, components of a drivetrain. For instance, the first element can be a shaft and the second element can also be a shaft. The shafts can be designed, for example, as a motor shaft and a gearbox shaft. For example, the first element can be a bicycle crankshaft and the second element a rotating element of a bicycle planetary gear system. For example, the two elements can form the bicycle crankshaft after being connected. One of the two elements can also be designed, for example, as a stationary component, such as a housing. The connection system can be designed to join the two elements together. The connection system can be designed to stiffen a defined press fit between the two elements.The two elements can also be connected using a transition fit or loose fit.

[0008] The first and second elements can be inserted into one another for connection. For example, the second element can have a recess into which the first element can be at least partially inserted. Conversely, the first element can also have a recess into which the second element can be at least partially inserted. The examples described below, in which the first element is inserted into the second element, also apply equally to configurations in which the second element is inserted into the first element. The two elements can be moved relative to each other for insertion. Insertion allows the two elements to be permanently connected. Insertion creates a connection arrangement from the two elements. The connection arrangement can be a two-part component. During insertion, the two elements can be pressed together.The recess in one of the two elements for receiving the other of the two elements can be designed to correspond to an outer contour of an insertion section of the other of the two elements. The recess in one of the two elements for receiving the other of the two elements can, for example, be cylindrical.

[0009] The first element has a cutting tooth. The cutting tooth can have teeth, each with a cutting end. The teeth of the cutting tooth can be arranged around the circumference of the first element. The cutting end can be designed, for example, as a cutting edge or a cutting surface. A toothed section can adjoin the cutting tooth, through which torque can be transmitted from the first component to the second component after they are joined. The cutting tooth, for example, cuts material from the second element during insertion, such as on an adjacent surface. The toothed section does not cut material from the second element during insertion. Torque transmission can occur, for example, via the respective tooth flanks of the cutting tooth, such as the tooth flanks of the toothed section.The first element can, for example, be hardened in the cutting area. The first element can, for example, be made of a harder material than the second element. The cutting teeth can, for example, extend axially only over a portion of the first element. The cutting teeth can, for example, protrude radially, for instance, towards the second element after insertion.

[0010] The cutting teeth are designed to cut a corresponding tooth profile into the second element in a cutting direction during insertion. The cutting direction can, for example, correspond to the insertion direction of the first element into the second element. The cutting direction can also be the direction in which the material is cut from the second element during insertion. A chip is formed, for example, for each tooth of the cutting teeth. The chip is pushed ahead of the cutting teeth, for example, through the cutting zone. The cutting direction can run from the point that is cut first during insertion to the point that is cut last. The cutting direction can be parallel to a longitudinal axis of the first component and, alternatively or additionally, to a longitudinal axis of the second component.The cutting direction can be coaxial with a longitudinal axis of a recess in one of the two components. The tooth profile can have a corresponding number of teeth to the teeth of the cutting teeth of the first element. The teeth of the tooth profile can be arranged on a circumference of the second element. Torque can be transmitted between the first and second components via the tooth profile after they are joined. The torque transmission can be achieved, for example, via respective... :The tooth flanks of the tooth profile are connected. The tooth flanks of the tooth profile and the cutting teeth can be in contact with each other after the two elements are joined. The first element, and alternatively or additionally the second element, can have a cylindrical basic shape in the area of ​​the connection arrangement, the cutting teeth, and the tooth profile. The cutting teeth and the tooth profile can form a positive-locking connection after the first element is joined to the second element.

[0011] The second element has a chip release groove. Upon reaching a mounting position, the chip release groove causes chip separation from the second element by the cutting teeth. For example, the cutting area of ​​the cutting teeth, along with the chip being pushed in front of it, can break into the chip release groove, thus causing chip separation. Alternatively, the cutting teeth can break through a wall of the chip release groove and thus be pushed into it. Complete chip separation or at least partial chip separation can occur. All chips or at least one chip can be separated from a tooth of the second element's tooth profile. There can be one chip per tooth of the cutting teeth. Where descriptions below refer to a single chip, they can equally apply to multiple chips, where applicable.The chip release groove can be designed, for example, as a circumferential groove. Alternatively, a separate chip release groove can be provided for each tooth of the cutting teeth. The assembly position can be a desired connection position of the two elements. The assembly position can be a final position when the two elements are joined. The assembly position can be defined, for example, by a stop.

[0012] Chip separation allows the chip to fall into a chip chamber. Chip separation prevents the chip from hindering the movement of the two elements into their final assembly position, for example, because the chip might block the complete insertion of the first element into the second element at the cutting edge. Furthermore, it prevents chip compression in the assembly position, which can cause the chip to become spring-like. This tension of an uncompressed chip can generate a high force that pushes the two elements out of their assembly position. It was observed that even a chip that is not compressed in its final position can create a spring effect during operation, thus pushing the two elements out of their assembly position. Chip separation prevents this effect.Accordingly, axial fixation, for example by a fixing element, can be less severe, since it does not potentially have to withstand the clamping force of an uncut chip. Thus, a fixing screw can have a smaller diameter. Furthermore, the overall clamping force required to hold the two elements together in the assembly position can be lower.

[0013] Furthermore, the chip removal groove can facilitate assembly. At the end of a pressing operation, the pressing force can decrease because the chip is removed. This allows a press log to show that the assembly position has been reached. Without chip removal, however, the pressing force can increase continuously without an intermediate drop when the assembly position is reached, making it unclear whether the pressing action is against a stop or just a jammed chip.

[0014] In a further embodiment of the connection system, the cutting teeth, with their leading end region in the cutting direction, can project into the chip release groove in the assembly position. The chip release groove can be arranged such that, for example, the cutting area and optionally also a portion of the toothed area project into the chip release groove in the assembly position. This ensures chip separation. For example, the chip release grooves of both elements are axially located in the same area in the assembly position. The cutting edge can thus be at least partially or completely separated from the walls of the chip release groove or even entirely from the second element.

[0015] In another embodiment of the connection system, the chip release groove can extend further in a vertical direction than the respective teeth of the cutting teeth. At least the front end portion, which projects into the chip release groove, can, for example, be less high than the chip release groove itself. The vertical direction can be, for example, radial. For the teeth of the cutting teeth, the vertical direction can correspond to an extension from the root to the tip. Thus, the tip of a tooth of the cutting teeth can be less high than the chip release groove. This allows the chip to be separated particularly cleanly upon reaching the assembly position. The front end portion of the cutting teeth can be accommodated in a clearance without contact with the second element. The chip release groove can enlarge the chip chamber for the chips produced when cutting the tooth profile.This can, for example, significantly simplify the cutting of an axially long tooth profile.

[0016] In a further embodiment of the connection system, a wall of the chip release groove facing the cutting direction may be steeper than a wall of the chip release groove facing away from the cutting direction. The wall of the chip release groove facing the cutting direction may, for example, be penetrated by the cutting teeth when the assembly position is reached. The wall of the chip release groove facing away from the cutting direction may, for example, not be reached by the cutting teeth when the assembly position is reached. The steepness of a wall may be defined by an angle to the cutting direction. For example, the wall of the chip release groove facing the cutting direction may extend orthogonally to the cutting direction. Alternatively, the wall of the chip release groove facing away from the cutting direction may extend at an angle of less than 90° to the cutting direction.The steeper the wall of the chip release groove facing the cutting direction, the shorter the chip release groove can be. This also results in better chip release.

[0017] A shallower angle of the chip-release groove wall facing the cutting direction can simplify its production. Furthermore, the force required when the cutting teeth break through this wall can be reduced.

[0018] In a further embodiment of the connection system, the connection system may include a fixing element. The connection system may be designed to fix the first element to the second element in the cutting direction by means of the fixing element. For example, the fixing element may block axial movement of the two elements relative to each other in the cutting direction.

[0019] This reliably prevents the two elements from separating, for example due to vibrations. The fixing element can, for example, be used as

[0020] The fixing element can be designed as a screw or dowel pin. For example, the second element can have a through-hole through which the fixing element is inserted and engages in an internal thread of the first element. By tightening the screw, the two elements can then be fixed together. The fixing element can also be used to slide the two elements together. For example, by tightening the screw, the first element can be pressed into the second element. Tightening the screw can also cut the tooth profile with the cutting teeth. This can make assembly particularly simple and require few steps. The connection system can be designed to use the fixing element to pull the first and second elements together in one cutting direction for joining them, cutting the tooth profile, and forming the press fit.Alternatively or additionally, a press can be provided for this purpose.

[0021] In a further embodiment of the connection system, the second element may have a recess for inserting the first element. For example, the second element may have a cylindrical through-hole or a cylindrical blind hole into which a corresponding section of the first element with the cutting teeth can be inserted. The second element may have a radial recess at its end in the cutting direction, i.e., for example, on the bottom side. This radial recess may form a further groove, which, however, may only simplify the manufacturing of the recess and does not collect chips when connected. The cutting teeth may be formed on an outer circumference of the first element. For example, the first element with the cutting teeth may thus cut the tooth profile on an inner circumference of the recess of the second element.The manufacturing of the cutting teeth on the outer circumference of the first element can be particularly simple and cost-effective. The chip release groove can be formed on an inner circumference of the second element, which, for example, defines the recess. The chip release groove can be axially spaced from an end region of the recess and the bottom-side radial recess in the direction of cutting.

[0022] In a further embodiment of the connection system, the first element may have a recess for inserting the second element. The cutting teeth may be formed on an inner circumference of the recess of the first element. The chip-removal groove may be formed on an outer circumference of the second element. The recess of the first element slides along this outer circumference during insertion. The design here can therefore be the reverse of the embodiment described above. For example, the first element may have a cylindrical through-hole or a cylindrical blind hole into which a corresponding section of the second element can be inserted. The tooth profile can then be cut in this section of the second element. For example, the first element with its cutting teeth can thus cut the tooth profile on an outer circumference of the second element.The cutting teeth on the inner circumference of the first element can be well protected from damage before the two elements are joined together.

[0023] In a further embodiment of the connection system, the first and second elements can be designed to abut each other in the cutting direction during joining. This allows for a defined connection or assembly position. For example, when inserted into the blind hole recess of the second element, the first element can abut the bottom of the blind hole. This achieves a defined assembly position. The abutment can also be formed, for example, by a protruding portion of the first element that abuts the outer wall of the recess of the second element during insertion.

[0024] In a further embodiment of the connection system, the first element may have a first mating surface in the cutting direction in front of the cutting teeth. This first mating surface can guide the first and second elements during insertion. It can also absorb bending loads. The second element may have a first mating surface corresponding to the first mating surface of the first element. These two first mating surfaces may be arranged adjacent to each other in the connected state, for example, abutting each other in the same axial area of ​​the crank axle. The two first mating surfaces may, for example, form a loose fit, a transition fit, or an interference fit. The fit in the area of ​​the first mating surfaces may be tighter than in the area of ​​the teeth.For example, the first mating surface of the first element can be formed by a cylindrical section in the cutting direction in front of the cutting teeth. The first mating surface of the first element can, for example, ensure concentricity of the two elements during their insertion before the start of a cutting operation on the tooth profile. The first mating surface of the first element can be separated from the cutting teeth, for example, by a circumferential cutting relief groove. This prevents the mating surface from interfering with the cutting process.

[0025] In a further embodiment of the connection system, the first element may have a second mating surface behind the cutting teeth in the cutting direction. This second mating surface can also withstand bending loads. The second element may have a second mating surface corresponding to the second mating surface of the first element. These two second mating surfaces may be arranged adjacent to each other in the connected state, for example, abutting each other in the same axial region of the crank axle. The two second mating surfaces may, for example, form a loose fit, transition fit, or interference fit. A fit in the region of the second mating surfaces may be tighter than in the region of the teeth. For example, the second mating surface of the first element may be formed by a cylindrical section behind the cutting teeth in the cutting direction.The second mating surface can also rest against another crankshaft component or drivetrain component, for example, to support bending forces. For instance, the second mating surface can rest against a bottom bracket bearing. The second mating surface of the first element can be separated from the cutting teeth, for example, by a circumferential groove. This can facilitate manufacturing. In a further embodiment of the connection system, the first element can have a cutting edge relief groove in the cutting direction in front of the cutting teeth. The cutting edge relief groove can be arranged in the cutting direction between the cutting teeth and the mating surface. The cutting edge relief groove can be designed as a circumferential groove. A separate cutting edge relief groove can also be provided for each tooth of the cutting teeth.In the cutting edge relief groove, the chip can be deflected before reaching the assembly position during the cutting process, thus reducing joining forces. In the assembly position, the cutting edge relief groove and the chip release groove can form a chip chamber. Detached chips can be collected in this chip chamber. The cutting edge relief groove can be at least partially overlapping with the chip release groove in the assembly position. The cutting edge relief groove can also be connected to the chip release groove in the assembly position.

[0026] In another embodiment of the connection system, a toothed section of the cutting teeth can have a constant cross-section. This can reduce the cost of manufacturing the cutting teeth. Furthermore, it allows for the formation of a continuous, uniform tooth profile between the two elements. For example, the cutting teeth can have a constant height and width after the cutting edge. The cross-section can change only at the respective axial ends of the cutting teeth, for instance, to transition into the mating surfaces and, alternatively or additionally, to form the cutting edge.

[0027] A second aspect concerns a connection arrangement with a first element and a second element. The connection arrangement can be formed from the connection system according to the first aspect. Further features, embodiments, and advantages are described in the first aspect. Conversely, features, embodiments, and advantages of the second aspect also represent features, embodiments, and advantages of the first aspect. The connection arrangement can, for example, form a two-part crank arm of a bicycle, such as a pedelec. The first element of the connection arrangement has a cutting tooth profile, and the second element has a corresponding tooth profile. The tooth profile was cut by the cutting tooth profile when the first and second elements were inserted into each other.The cutting teeth and tooth profile can form an interference fit, transition fit, or loose fit. The second element has a chip release groove, which, for example, causes chip separation from the second element by the cutting teeth when the first and second elements are inserted into each other and a mounting position is reached. The connection assembly can contain the separated chip. The chip can be collected in the chip release groove and, alternatively or additionally, in a cutting edge relief groove.

[0028] Another aspect concerns a bicycle drivetrain with the connection arrangement described in the second aspect. Yet another aspect concerns a bicycle with such a drivetrain. Further features, embodiments, and advantages are described in the second and first aspects. Conversely, features, embodiments, and advantages of the second and first aspects also represent features, embodiments, and advantages of the further aspects.

[0029] Fig. 1 shows a schematic sectional view of a pedal crank shaft with a first element and a second element.

[0030] Fig. 1 shows a schematic sectional view of a pedal crank shaft with a first element 20 and a second element 22. The two elements 20 and 22 are designed as pedal crank shaft components. The second element 22 has a cylindrical recess 24 into which the first element 20 has been inserted with a cylindrical end section. Thus, the pedal crank shaft is formed from a connection system with the two elements 20 and 22.

[0031] The first element 20 has a cutting tooth profile 26 on its outer circumference in an axial section, which is formed by radially outer teeth 28. To connect the two elements 20, 22, the first element 20 is inserted along its axial extent in an insertion direction, and thus a cutting direction, towards the bottom of the recess 24 into the second element 22. The bottom of the recess forms a stop for the first crank arm section 20, thereby defining an assembly position. The cutting direction is illustrated in Fig. 1 by arrow 34. The recess has a manufacturing-related indentation at its bottom. At a leading end of the cutting tooth profile 26 in this cutting direction, each of the teeth 28 of the first crank arm section 20 has a cutting area 30.This cutting area 30 cuts a tooth profile 32 corresponding to the cutting area of ​​the cutting teeth 26 into the recess 24 of the inner circumference of the second crank arm section 22. A chip is cut from the second element 22 for each tooth 28 of the cutting teeth 26. The tooth profile 32 has a constant cross-section along its longitudinal extent in the cutting direction. The teeth of the tooth profile 32 of the second crank arm section 22 have a constant height and a constant width.

[0032] The second element 22 has a through-opening 36 at the base of the recess 24. A fixing element in the form of a screw 38 is arranged in the through-opening 36. The screw 38 fixes the first element 20 to the second element 22 in the cutting direction and thus axially. The screw 38 engages with an internal thread in a through-opening 42 of the first element 20. By tightening the screw 38, the first element 20 can also be drawn into the recess 24 to connect the two elements 20 and 22, and thus pressed in. During this drawing in and insertion of the first element 20 into the second element 22, the tooth profile 32 is also cut into the second crank arm section 22. Alternatively, the pressing in can be carried out using a press without using the screw 38.

[0033] The first element 20 has, at its end facing the bottom of the recess 24 and thus at the front end in the cutting direction, a first cylindrical end piece 44 in front of the cutting teeth 26 and the cutting area 30, which forms a first mating surface on its outer circumference. The first mating surface guides the first pedal crank shaft part 20 and the second pedal crank shaft part 22 against each other during engagement and ensures concentricity of the two elements 20, 22 before the tooth profile 32 begins to cut. Furthermore, in the connected state shown, the first mating surface rests against a corresponding mating surface of the second pedal crank shaft part 22. The first mating surfaces can thus withstand bending loads. The first mating surface and the end piece 44 are axially separated from the cutting teeth 26 by a circumferential cutting relief groove 46 in the first pedal crank shaft part 20.When the tooth profile 32 cuts into the second element 22, the respective chips are picked up and carried along in the cutting relief groove 46. This reduces the resistance of the resulting chips to the cutting of the tooth profile 32.

[0034] The first crankshaft section 20 has a second cylindrical end piece 50j on its end facing away from the bottom of the recess 24 and thus behind the cutting teeth 26 and the cutting area 30 in the cutting direction. This end piece forms a second mating surface on its outer circumference. This second mating surface rests against a bottom bracket in a section not shown and also absorbs bending loads.

[0035] The second element 22 has a circumferential chip-removal groove 60 on its inner circumference, which defines the recess for receiving the first element 20. Upon reaching the assembly position, chip separation from the second element 22 is caused by the cutting teeth 26 through the chip-removal groove 60. In the assembly position, the cutting teeth 26, with their leading end region in the cutting direction 34, project into the chip-removal groove in the cutting direction. ::which causes a chip to be separated. In the example shown, the cutting tooth 26 projects axially, or in the cutting direction, into the chip release groove 60 by at least an average or maximum chip thickness. In the example shown, this is 0.4 mm. As a result, the chip is cleanly separated by each tooth 28 of the cutting tooth 26 against a wall of the chip release groove 60 facing the cutting direction 34 as it breaks through. The chip release groove 60 extends further in a vertical direction, which here is a radial direction, than the respective teeth 28 of the cutting tooth 26. Therefore, one tooth surface of the teeth 28 of the cutting tooth 26 is free in the chip release groove 60. The wall of the chip removal groove 60 facing the cutting direction 34 is steeper relative to the axial extent of the second element 22 and thus to the cutting direction 34 than a wall of the chip removal groove 60 facing away from the cutting direction 34.The chip release groove 60 and the cutting edge relief groove 46 are arranged overlapping in an axial area in the assembly position and are thus connected to each other. The chip release groove 60 and the cutting edge relief groove 46 together form a chip space in which separated chips are collected. The chip space has a minimum size corresponding to the volume of separated chips.

[0036] Reference sign

[0037] 20 first element;

[0038] 22 second element

[0039] 24 cylindrical recesses

[0040] 26 cutting teeth

[0041] 28 teeth

[0042] 30 cutting area

[0043] 32 Tooth Profile

[0044] 34 Arrow V Cutting direction

[0045] 36. Passage opening of the second element-

[0046] 38 Screw / Fixing element

[0047] 42 Through opening of the first element¬

[0048] 44 first end piece / fitting surface

[0049] 46 Cutting relief groove

[0050] 50 second end piece / fitting surface

[0051] 60 Chip removal groove

Claims

Patent claims 1. Connection system comprising a first element (20) and a second element (22), wherein the first element (20) and the second element (22) are insertable into one another for connection, wherein the first element (20) has a cutting tooth (26) which, upon insertion, cuts a corresponding tooth profile (32) into the second element (22) in a cutting direction (34), wherein the second element (22) has a chip removal groove (60) which, upon reaching an assembly position, causes chip separation from the second element (22) by the cutting tooth (26).

2. Connection system according to claim 1, characterized in that the cutting toothing (26) with its front end region in the cutting direction (34) projects into the chip removal groove (60) in the cutting direction in the assembly position.

3. Connection system according to claim 1 or 2, characterized in that the chip removal groove (60) extends further in a vertical direction than the respective teeth (28) of the cutting teeth (26).

4. Connection system according to one of the preceding claims, characterized in that a wall of the chip removal groove (60) facing the cutting direction is steeper than a wall of the chip removal groove (60) facing away from the cutting direction.

5. Connection system according to one of the preceding claims, characterized in that the connection system has a fixing element (38), wherein the connection system is designed for fixing the first element (20) to the second element (22) in the cutting direction (34) by means of the fixing element (38).

6. Connection system according to one of the preceding claims, characterized in that the second element (22) has a recess (24) for the insertion of the first element (20) and the cutting teeth (26) are formed on an outer circumference of the first element (20).

7. Connection system according to one of claims 1 to 5, characterized in that the first element (20) has a recess (24) for the insertion of the second element (22) and the cutting teeth (26) are formed on an inner circumference of the recess (24) of the first element (20).

8. Connection system according to one of the preceding claims, characterized in that the first element (20) and the second element (22) are designed to strike each other when connecting them in the cutting direction (34).

9. Connection system according to one of the preceding claims, characterized in that the first element (20) has a first mating surface (44) in the cutting direction (34) in front of the cutting teeth (26).

10. Connection system according to one of the preceding claims, characterized in that the first element (20) has a cutting relief groove (46) in the cutting direction (34) in front of the cutting teeth (26).

11. Connection arrangement with a first element (20) and a second element (22) which are inserted into one another, wherein the first element (20) has a cutting tooth (26) and the second element (22) has a corresponding tooth profile (32) which was cut by the cutting tooth (26) when the first element (20) and the second element (22) were inserted into one another, wherein the second element (22) has a chip removal groove (60) which caused chip removal from the second element (22) by the cutting tooth (26) when the first element (20) and the second element (22) were inserted into one another and a mounting position was reached.

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