JP2006038128A - Propeller shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a propeller shaft having a structure capable of surely generating and advancing breaking by a required low load. <P>SOLUTION: This propeller shaft has an FRP cylindrical body and a metallic joint pressed in an end of the FRP cylindrical body. The propeller shaft is characterized in that the metallic joint is provided with a flange capable of transmitting a shaft directional compressive load applied to the metallic joint to the end surface of the FRP cylindrical body, and the end of the FRP cylindrical body is provided with a layered and annular trigger part extending in the shaft direction from the end surface of the FRP cylindrical body in a position corresponding to an outer diameter of the flange part and becoming a starting point of the breaking of the FRP cylindrical body to the shaft directional compressive load. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a propeller shaft (drive propulsion shaft) for an automobile or the like, and more particularly to a propeller shaft configured using an FRP cylindrical body.

  In recent years, there has been a strong demand for weight reduction of automobiles for the purpose of improving fuel efficiency from the viewpoints of energy saving and global environmental protection. As one of the means, it has been considered to replace the propeller shaft with one made of FRP (fiber reinforced plastics) instead of metal. At that time, there are various types of reinforcing fibers to be used. For example, carbon fibers, glass fibers, aramid fibers, and the like have been studied. Among them, carbon fibers excellent in terms of specific strength and specific elastic modulus are reinforced. CFRP (carbon fiber reinforced plastics), which is used as a fiber, is considered to be promising and has already been partially adopted.

  Since the propeller shaft of an automobile needs to transmit a large torque generated from the engine, it requires a torsional strength of about 1,000 to 4,000 Nm. Conventional CFRP propeller shafts, in particular, the main body cylinder portion, as described in Patent Document 1 and the like, are used to transmit a necessary torque in order to transmit a necessary angle, a stacking configuration, a shaft size (inner diameter, outer (Diameter, wall thickness), types of reinforcing fibers used, fiber content, and the like. By appropriately setting these design parameters, it is possible to achieve the torsional strength required for practical use as described above. Further, it is also required that the critical rotational speed is about 5,000 to 15,000 rpm so that resonance does not occur during high-speed rotation. Therefore, in order to satisfy these basic requirements, the main body made of FRP considers parameters such as the type and content of reinforcing fibers, the arrangement direction of reinforcing fibers, the layer configuration, outer diameter, inner diameter, and wall thickness. Design is made. For example, the following is considered in selecting the arrangement direction of the reinforcing fibers. That is, with respect to the torsional strength, it is most effective to arrange the reinforcing fibers in a spiral shape at an angle of ± 45 ° with respect to the axial direction of the main body. It is most effective to arrange them in the circumferential direction at an angle of ± 80 to 90 °. Further, mainly regarding the critical rotational speed, reinforcing fibers are arranged in the axial direction as much as possible to increase the bending elastic modulus in the axial direction so that a high bending resonance frequency can be obtained.

  As described above, in the main body cylinder, there are the most effective reinforcing fiber arrangement directions with respect to basic requirements such as torsional strength and dangerous rotation speed. Therefore, a layer configuration in which arrangement directions suitable for these requirements are combined is adopted. However, since the problem of torsional strength can be solved from dimensions such as outer diameter and wall thickness, usually, priority is given to the critical rotational speed, which has a large dependence on the arrangement direction of reinforcing fibers. The ratio of the layers arranged at a small angle with respect to the axial direction is increased. However, this causes problems as described below.

  That is, in addition to weight reduction, it is important to ensure the safety of passengers in the event of a collision. The design philosophy of automobiles in recent years for ensuring safety is dominated by the fact that the body has a crushable structure and the impact energy at the time of collision is absorbed by deformation and destruction of the body, thus mitigating rapid acceleration on the passenger. However, if the FRP main body cylinder is designed under the above-mentioned concept of giving priority to the dangerous rotation speed, the strength against the axial compressive load is inevitably increased, and the body is destroyed at the time of collision, and the destruction is successively performed. When the propeller shaft is reached by advancing, the propeller shaft acts like a thick rod and the impact energy absorbing effect is lost.

  In an attempt to solve such a problem, the invention described in Patent Document 2 is such that the joint moves in the axial direction at the joint surface with the main body cylinder by a compressive load at the time of collision, and at the same time, the joint gradually moves the entire main body cylinder from its end. Propeller shafts that are expanded and destroyed are proposed. However, in this conventional propeller shaft, in order to ensure the movement of the joint, the main body cylinder and the joint must be joined through complicated tooth shapes and separating agents, which not only makes the structure complicated, The intricacies of unavoidable. In addition, when attempting to press-fit a joint in a propeller shaft having such a configuration, the main body cylinder must be strong enough to withstand the force during press-fitting. Spread and make destruction difficult. That is, it is difficult to satisfy the above-mentioned basic requirements and conflicting requirements such as expansion and destruction at the same time.

As described above, any of the conventional propeller shafts may be difficult to be balanced in terms of basic requirements such as torsional strength and dangerous rotational speed and ensuring the safety of passengers in the event of a collision.
JP-A-2-236014 JP-A-3-37416

  Therefore, the object of the present invention is to ensure that the FRP propeller shaft has the characteristics of high torsional strength and dangerous rotational speed required for automobiles and the like, and is adapted to a crashable vehicle body etc. with respect to the axial load. An object of the present invention is to provide a propeller shaft having a structure capable of reliably generating and advancing fracture at a necessary low load.

  In order to solve the above problems, a propeller shaft according to the present invention is a propeller shaft having an FRP cylindrical body and a metal joint press-fitted into an end of the FRP cylindrical body, and the metal joint A flange portion capable of transmitting an axial compressive load applied to the metal joint to the end surface of the FRP cylindrical body, and a position corresponding to the outer diameter of the flange portion at the end portion of the FRP cylindrical body. In this embodiment, a layered and annular trigger portion is provided which extends in the axial direction from the end face of the FRP cylindrical body and serves as a starting point of destruction of the FRP cylindrical body against the axial compression load.

  In the propeller shaft, the end portion of the FRP cylindrical body is located on the radially inner side, and includes a reinforcing layer including a circumferential winding layer of reinforcing fibers (for example, a winding layer of ± 70 to 90 degrees with respect to the axial direction) , Located outside the reinforcing layer, and extending over the entire axial length of the cylindrical body for transmitting torque, including a spiral wound layer of reinforcing fibers (for example, a wound layer of ± 10 to 65 degrees with respect to the axial direction) A position where the outer diameter of the flange portion corresponds to the boundary between the reinforcing layer and the cylinder forming layer, and the trigger portion corresponds to the boundary. Is provided.

  Moreover, the trigger part is comprised by embedding a sheet-like thing, for example. For example, at the boundary of the FRP cylindrical body, the adhesive shear strength with the matrix resin used for the FRP of the cylindrical body is lower than the interlayer shear strength of FRP, and the layer thickness is a laminated structure of reinforcing fibers Is formed by embedding a sheet-like material that is thinner than the thickness of a single layer of FRP of the cylindrical body forming As the shape of the sheet-like material forming the trigger portion, a belt-like sheet having a constant width can be annularly extended, and the axially inner end surface of the sheet-like material is formed in a wave shape or a zigzag shape. A shape can also be adopted.

  This sheet-like material can be selected from a plastic film, a metal thin plate, a metal net, an organic fiber fabric, a glass fiber fabric, an aramid fiber fabric, and the like.

  FRP cylindrical body forming methods include filament winding molding, sheet winding molding, and the like. The target propeller shaft FRP cylinder is formed by inserting a sheet-like material that forms a trigger portion at a predetermined position during molding. The body is obtained.

  As another method of forming the trigger portion, an annular groove is formed in the boundary layer portion of the FRP cylindrical tube formed by a predetermined method, that is, an annular slit is formed. By doing so, a desired trigger portion can be configured.

  As a more preferable structure, a recess having an outer diameter smaller than the inner diameter of the FRP cylindrical body is provided in front of the flange portion of the metal joint on the press-fitting side, and the axial length of the trigger portion is the recess. It is possible to employ a structure that is set to a length that is substantially the same as the axial length.

  In this structure, a serration portion is further provided on the outer periphery of the press-fitting portion of the metal joint into the FRP cylinder, and the inner diameter of at least the end of the FRP cylinder extends over the axial length of the recess. Thus, a structure that is set larger than the outer diameter of the serration portion of the metal joint can be employed.

  In such a propeller shaft, when an axial compressive load is applied to the FRP cylinder, the load is transmitted from the flange portion of the metal joint to the trigger portion at the end of the FRP cylinder, resulting in a large stress concentration in the trigger portion. Is generated and breakage starts and progresses, and the breakage starts with a smaller compressive load than other portions of the cylindrical body. In addition, all the trigger parts adopt a structure that does not substantially reduce the strength during press-fitting of metal joints and the torsional strength of FRP cylindrical bodies, so there is no problem in the required strength for normal use. Does not occur.

  As described above, the torsional strength required for the propeller shaft for automobiles can be achieved by optimizing the design of the FRP cylindrical body, so that the necessary torsional strength can be ensured by providing the trigger portion, For cylinder axial compression load, the cylinder body can be reliably destroyed with a load lower than the axial compression strength of the cylinder body, and the same impact energy absorption ability as the vehicle body itself can be exhibited. Can do.

  Further, a concave portion having an outer diameter smaller than the inner diameter of the cylindrical body is formed in front of the flange portion of the metal joint, and the axial length of the trigger portion is disposed in front of the flange portion. By setting the length, it becomes possible to use the trigger portion without applying a load to it during normal torque transmission.

  Furthermore, according to the axial length of the trigger part provided in the FRP cylindrical body, the inner diameter of the cylindrical body is made larger than the outer diameter of the serration part of the metal joint, thereby loading the trigger part when the metal joint is press-fitted. It becomes possible to assemble without loading.

  According to the present invention, the FRP cylindrical body end portion of the propeller shaft is provided with the trigger portion that is the starting point of the fracture against the compressive load in the cylinder axial direction in an appropriate form, and the compression fracture is reliably triggered. Since it starts and progresses from a part, the desirable form of destruction required at the time of a collision, etc. can be revealed, ensuring the high torsional strength required for automobiles and the like.

Hereinafter, preferred embodiments of a propeller shaft according to the present invention will be described with reference to the drawings.
1 to 3 show a propeller shaft according to a first embodiment of the present invention. In FIG. 1, 1 shows the entire propeller shaft, 2 is an FRP cylindrical body, 3 is a metal joint press-fitted into both ends of the FRP cylindrical body 2 (only one end is shown in FIG. 1). Respectively. In the present embodiment, the inner diameter of the FRP cylindrical body 2 is 74.05 mm, and the FRP cylindrical body 2 is ± 70 degrees with respect to the axial direction of the cylindrical body 2 located radially inward at the end. Reinforcing layer 2b including a circumferentially wound layer of reinforcing fibers wound at an angle of ˜90 degrees, and a spiral winding positioned on the outer side and having an angle of, for example, ± 10 degrees to 65 degrees with respect to the axial direction of cylindrical body 2 It consists of the cylinder formation layer 2a including the layer and extending over the full length of the cylindrical body 2. In this embodiment, the reinforcing layer 2b is formed of a straight portion having a thickness of 2.5 mm and an axial length of 60 mm and a tapered portion having a length of 60 mm toward the axial center. The cylinder forming layer 2a has a main layer composed of a plurality of ± 15 degrees layers extending over the entire length in the axial direction of the cylinder, and is formed to a thickness of 2.5 mm.

  The metal joint 3 has a serration portion 3a at the press-fitting portion into the FRP cylinder 2 and is axially compressed to the end surface of the FRP cylinder 2 at a position facing the end surface of the FRP cylinder 2. It has a flange portion 3b capable of transmitting a load. In this embodiment, a recess 3c having an outer diameter smaller than the inner diameter of the FRP cylindrical body 2 is provided in front of the flange portion 3b on the press-fitting side, and the axial length of the recess 3c is described later. The length is set to be substantially the same as the axial length of the trigger portion.

  The outer diameter of the flange portion 3b is preferably approximately matched to the diameter of the trigger portion of the FRP cylindrical body 2 at the radial position, and is 78.5 mm. The length of the recess 3c in the axial direction is set to 13 mm in consideration of the length of a trigger portion described later. The serration part 3a used a serration having a pitch of about 2 mm, a tooth height of 0.9 mm, a tip R of 0.05 mm, and a tooth tip angle of 90 degrees, and the outer diameter was processed to 74.45 mm. Therefore, it has a press-fitting allowance of 0.40 mm in diameter.

  In this embodiment, the trigger portion 4 that is the starting point of the fracture of the FRP cylindrical body 2 against the axial compression load (compression impact load) is formed by a layered and annular sheet-like material embedded in the end of the cylindrical body 2. Is formed. The trigger portion 4 is disposed at substantially the same position as the outer diameter of the flange 3b, and the axial length is 10 mm. The trigger part 4 by this sheet-like material can be embedded by inserting and winding a predetermined sheet-like material after laminating the inner circumferential winding reinforcing layer 2b when manufacturing the FRP cylindrical body 2. A metal joint 3 was press-fitted into the end portion of the FRP cylindrical body 2 by pressing, and both were integrated. The press-fitting speed at this time is preferably 1 to 20 mm / sec. If it is too slow, the working efficiency will be reduced, and if it is too fast, there is a concern of damaging the FRP cylinder 2. The final press-fitting load generated at this time was 4 tons.

  The material of the sheet-like material forming the trigger portion 4 is not particularly limited, but for example, a fluororesin film, a polyethylene terephthalate film, a polypropylene film, etc. are suitable. In addition, in order to optimize the function as the trigger part 4, depending on the case, you may perform mold release processing, such as apply | coating a mold release agent to the surface of a film.

  As the FRP matrix resin constituting the FRP propeller shaft of the present invention, an epoxy resin, a phenol resin, a polyimide resin, a vinyl ester resin, a thermosetting resin such as an unsaturated polyester is used, but other resins, for example, It is also possible to use thermoplastic resins such as polyamide, polycarbonate, and polyetherimide. Further, the reinforcing fibers are not limited to carbon fibers, and for example, glass fibers, aramid fibers, and the like can be used, and these can be used in combination.

  With the above structure, when an axial compressive load is applied, a large load is instantaneously applied from the flange portion 3b of the metal joint 3 to the trigger portion 4, and destruction always starts from the tip of the trigger portion 4. Then, as shown in FIG. 4, delamination failure proceeds at the boundary between the circumferential winding reinforcing layer 2b and the cylinder forming layer 2a. Furthermore, destruction of the cylindrical body forming layer 2a which is the main layer of the FRP cylindrical body 2 is advanced by the wedge effect of the separated circumferentially wound reinforcing layer 2b. In this embodiment, when an axial compression load was applied from the metal joint 3, the load was transmitted from the flange portion 3b to the trigger portion 4, an initial failure occurred at about 6 tons, and sequential failure proceeded.

  Since this trigger part 4 intentionally weakens the strength only against the axial compressive load at the edge of the FRP cylindrical body 2, the axial strength and the elastic modulus at other parts of the cylindrical body 2. In particular, it has substantially no effect on the torsional strength. Accordingly, the target axial compressive fracture is reliably started while the necessary torsional strength is ensured.

  The fracture start load for compression can be set to an optimum load by setting the material, thickness, length, etc. of the trigger portion.

  Moreover, as a form of the sheet-like material forming the trigger portion 4, as shown in FIG. 5, a belt-like sheet material may be simply extended in an annular shape (4 a in FIG. 5). It is also possible to use one having a back end face formed in a wave shape or a zigzag shape (4b in FIG. 5). By forming in a shape like the sheet-like material 4b, it is possible to further reduce the fracture start load when a compressive load is applied.

  Furthermore, the recess 3c having an outer diameter smaller than the inner diameter of the FRP cylindrical body 2 is provided in front of the flange portion 3b of the metal joint 3, and the axial length of the trigger portion 4 is the recess 3c. By setting the length equal to the axial length, it is possible to prevent an undesirable torque from acting on the trigger portion 4. The recess 3c can be easily formed by machining after the serration portion 3a is formed.

  In addition to embedding the sheet-like material, the trigger portion is formed at the boundary between the circumferentially wound reinforcing layer 2b and the cylindrical body forming layer 2a as shown in FIG. 6 of the propeller shaft 5 according to the second embodiment. In addition, an annularly extending slit 6 may be provided. For the processing of the slit 6, for example, a machining method can be used. In this way, by forming the trigger portion by arranging the trigger portion in the slit shape at the boundary portion, when an axial compressive load is applied as in the case where the trigger portion is formed by the sheet-like material, the slit tip portion is formed. Thus, stress concentration can be generated and used as a starting point of fracture.

  FIG. 7 shows a propeller shaft 7 according to a third embodiment of the present invention. Trigger portions 4 are formed at both ends of the FRP cylindrical body 2 by embedding an annular sheet-like material as in the first embodiment. In this embodiment, the inner diameter of at least the end portion 2c of the FRP cylindrical body 2 is larger than the outer diameter of the serration portion 3a of the metal joint 3 over the axial length of the recess 3c of the metal joint 3. In this embodiment, the inner diameter is increased in a tapered shape toward the outside.

  In this way, the inner diameter of the FRP cylindrical body 2 is longer than the outer diameter of the serration part 3a of the metal joint 3 over the length of the recess 3c at a position corresponding to the trigger part installation position of the FRP cylindrical body 2. By setting a large value, it is possible to prevent the generation of the axial compressive force caused by the serration cut of the metal joint 3 during press-fit assembly, and to prevent the trigger portion from starting to break at this stage. The large range of the inner diameter of the end portion can be set in accordance with the axial length of the trigger portion. The processing of the inner diameter can be provided by machining by cutting or the like, winding a release film or the like on a mandrel at the time of forming the FRP cylindrical body 2, and removing it after the forming. Moreover, the effect which prevents the damage to the cylinder 2 made from FRP from the load which acts at the time of press fit can also be anticipated.

  In the propeller shaft of the present invention, a sealing material may be disposed at an appropriate position (for example, each member end position) between the FRP cylindrical body and the metal joint. As the sealing material, a resin, a ring-shaped elastic body, a film or the like is appropriate. By providing such a sealing material, it is possible to more reliably prevent moisture and the like from entering, and to prevent corrosion of the joint.

  In addition, when a metal joint is press-fitted, it is necessary to grip the joint with a press-fitting jig, but the press-fitting jig must be connected to the joint so that it can be securely gripped and the joint is not damaged by pressure input. It is preferable to provide a stop or engaging portion. Such a locking or engaging portion can be configured by forming a stepped portion or a groove portion at an appropriate position on the outer surface of the joint.

  The result at the time of using the prior art which does not use this invention as a comparative example is shown. The configuration of the FRP cylindrical body and the metal joint was the same, and the trigger portion was not disposed on the FRP cylindrical body. When an axial compression load was applied in the same manner as described above, initial fracture occurred at about 13 tons. The effect of the trigger portion according to the present invention is obvious when compared with the breaking start load of about 6 tons in the first embodiment described above.

  The propeller shaft according to the present invention can be applied to any propeller shaft provided with an FRP cylindrical body, and is particularly suitable for an FRP propeller shaft of an automobile in which a crushable structure is adopted for a vehicle body.

It is a schematic sectional drawing which shows the principal part of the propeller shaft which concerns on the 1st embodiment of this invention. It is a side view of the metal coupling of the propeller shaft of FIG. It is a fragmentary sectional view of the cylinder made from FRP of the propeller shaft of FIG. It is a schematic sectional drawing of the propeller shaft end part which shows the progress of destruction in the propeller shaft of FIG. It is a perspective view which shows the example of the sheet-like material which forms a trigger part. It is a schematic sectional drawing which shows the principal part of the propeller shaft which concerns on the 2nd embodiment of this invention. It is a schematic sectional drawing which shows the principal part of the propeller shaft which concerns on the 3rd embodiment of this invention.

Explanation of symbols

1, 5, 7 Propeller shaft 2 FRP cylinder 2a Tube forming layer 2b Reinforcing layer 2c Enlarged inner diameter part 3 Metal joint 3a Serration part 3b Flange part 3c Recessed part 4 Trigger part 4a, 4b Sheet-like material forming the trigger part 6 Slit

Claims (7)

  A propeller shaft having an FRP cylindrical body and a metal joint press-fitted into an end of the FRP cylindrical body, wherein an axial compressive load applied to the metal joint is applied to the metal joint. A flange portion capable of transmitting to the end surface of the cylindrical body is provided, and the end portion of the FRP cylindrical body extends in the axial direction from the end surface of the FRP cylindrical body at a position corresponding to the outer diameter of the flange portion. A propeller shaft, characterized in that a layered and annular trigger portion is provided as a starting point of destruction of an FRP cylindrical body against a compressive load.   Forming a cylindrical body including an end portion of the cylindrical body made of FRP positioned radially inside and including a circumferential wound layer of reinforcing fibers and a spiral wound layer of reinforcing fibers positioned outside the reinforcing layer And the outer diameter of the flange portion is set at a position corresponding to the boundary between the reinforcing layer and the cylinder forming layer, and the trigger portion is provided at a position corresponding to the boundary. The propeller shaft according to claim 1.   The propeller shaft according to claim 1, wherein the trigger portion is configured by embedding a sheet-like material.   The propeller shaft according to claim 1, wherein the trigger portion is configured by forming a slit.   A concave portion having an outer diameter smaller than the inner diameter of the FRP cylindrical body is provided in front of the flange portion of the metal joint on the press-fitting side, and the axial length of the trigger portion is equal to the axial length of the concave portion. The propeller shaft according to any one of claims 1 to 4, wherein the propeller shaft is set to substantially the same length.   A serration portion is provided on the outer periphery of the press-fitting portion of the metal joint into the FRP cylindrical body, and the inner diameter of at least the end of the FRP cylindrical body extends over the axial length of the concave portion. The propeller shaft according to claim 5, wherein the propeller shaft is set to be larger than an outer diameter of the serration portion.   4. The propeller shaft according to claim 3, wherein an end face in an axial direction of the sheet-like material forming the trigger portion is formed in a wave shape or a zigzag shape.

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