Shaft-tube joint structure of carbon fiber reinforced plastic drive shaft

Abstract

The present invention discloses a shaft-tube joint structure of a carbon fiber reinforced plastic (CFRP) drive shaft. The shaft-tube joint structure includes a hollow shaft tube, a plurality of first rectangular teeth being uniformly and circumferentially arranged at both ends of the hollow shaft tube; two shaft-tube joints which are respectively fixed at two ends of the hollow shaft tube, the thickness of the shaft-tube joint being smaller than that of the hollow shaft tube, and an inner wall of the shaft-tube joint being smoothly connected to an inner wall of the hollow shaft tube; and a universal joint, an end thereof being tubular, a plurality of second rectangular teeth being uniformly and circumferentially arranged, the universal joint being matched with and sleeving the outer wall of the shaft-tube joint, and the second rectangular teeth being meshed with the first rectangular teeth.

Claims

1. A shaft-tube joint structure of a carbon fiber reinforced plastic (CFRP) drive shaft, the shaft-tube joint structure comprising: a hollow shaft tube, a plurality of first rectangular teeth being uniformly and circumferentially arranged at both ends of the hollow shaft tube; two shaft-tube joints which are respectively fixed at two ends of the hollow shaft tube, a tube wall thickness of the shaft-tube joint being smaller than that of the hollow shaft tube, and an inner wall of the shaft-tube joint being connected to an inner wall of the hollow shaft tube; and a universal joint, an end of the universal joint being tubular, a plurality of second rectangular teeth being uniformly and circumferentially arranged, the universal joint sleeving the outer wall of the shaft-tube joint, and the second rectangular teeth being meshed with the first rectangular teeth.

2. The shaft-tube joint structure of the CFRP drive shaft according to claim 1, wherein the hollow shaft tube and the shaft-tube joint are both made of a CFRP, and carbon fibers are arranged at 0°, ±45° and 90° to an axial direction of the hollow shaft tube.

3. The shaft-tube joint structure of the CFRP drive shaft according to claim 2, wherein: the hollow shaft tube has a length of 200-5000 mm, an inner diameter of 10-200 mm and an outer diameter of 15-300 mm; and an axial length of the shaft-tube joint is 5-100 mm.

4. The shaft-tube joint structure of the CFRP drive shaft according to claim 3, wherein each of the rectangular teeth has a thickness of 3-30 mm.

5. The shaft-tube joint structure of the CFRP drive shaft according to claim 1, wherein the tube wall thickness of the shaft-tube joint is 20%-60% that of the hollow shaft tube.

6. The shaft-tube joint structure of the CFRP drive shaft according to claim 5, wherein the universal joint is made of steel B480QZR.

7. The shaft-tube joint structure of the CFRP drive shaft according to claim 6, wherein the universal joint is connected to the hollow shaft tube and the shaft-tube joint by structural adhesive.

8. The shaft-tube joint structure of the CFRP drive shaft according to claim 7, wherein the hollow shaft tube and the shaft-tube joint are manufactured by a hot press curing molding process.

9. The shaft-tube joint structure of the CFRP drive shaft according to claim 8, wherein: there are at least two first rectangular teeth; and each of the first rectangular teeth form a central angle of 360°/(number of first rectangular teeth*2) in circumferential distribution on the hollow shaft tube.

10. The shaft-tube joint structure of the CFRP drive shaft according to claim 1, wherein the other end of the universal joint is connected to a gearbox or a main reducer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a two-dimensional structural diagram of a drive shaft according to the present invention;

(2) FIG. 2 is a three-dimensional structural diagram of a drive shaft tube and a joint according to the present invention;

(3) FIG. 3 is a three-dimensional structural diagram of a drive shaft according to the present invention;

(4) FIG. 4 shows a stress distribution value of a joint of a drive shaft under a rated working condition according to the present invention;

(5) FIG. 5 shows a first-order modal shape and frequency of a drive shaft according to the present invention; and

(6) FIG. 6 is a failure index of a drive shaft tube according to the present invention.

DETAILED DESCRIPTION

(7) The present invention is further described in detail below with reference to the accompanying drawings, so as to enable those skilled in the art to implement it with reference to the specification.

(8) As shown in FIGS. 1-3, a shaft-tube joint structure of a CFRP drive shaft according to the present invention mainly includes a shaft tube 100 which has a hollow structure, where a plurality of first rectangular teeth 110 are uniformly and circumferentially arranged at both ends of the hollow shaft tube, and the first rectangular teeth 110 extend to both ends in the axial direction of the hollow shaft tube 100. Two shaft-tube joints 200 are fixed at both ends of the hollow shaft tube 100 respectively, and are formed together with the hollow shaft tube 100. The thickness of the shaft-tube joint 200 is smaller than that of the hollow shaft tube 100, and an inner wall of the shaft-tube joint 200 is smoothly connected to an inner wall of the hollow shaft tube 100, so a boss is formed at the joint of an outer wall of the shaft-tube joint 200 and an outer wall of the hollow shaft tube 100. An end of a universal joint 300 is tubular, and a plurality of second rectangular teeth 310 are circumferentially arranged. The universal joint 300 is matched with and sleeves the outer wall of the shaft-tube joint 200, and the second rectangular teeth 310 are meshed with the first rectangular teeth 110.

(9) In another example, the hollow shaft tube 100 and the shaft-tube joint 200 are both made of a CFRP, and carbon fibers are arranged at 0°, ±45° and 90° to the axial direction of the hollow shaft tube.

(10) In another example, an axial length of the shaft-tube joint 200 is 5-100 mm.

(11) In another example, the rectangular teeth each have a thickness of 3-30 mm.

(12) In another example, the wall thickness of the shaft-tube joint 200 is 20%-60% that of the hollow shaft tube 100.

(13) In another example, the universal joint 300 is made of steel B480QZR.

(14) In another example, the universal joint 300 is connected to the hollow shaft tube 100 and the shaft-tube joint 200 by structural adhesive.

(15) In another example, the hollow shaft tube 100 and the shaft-tube joint 200 are manufactured by a hot press curing molding process.

(16) In another example, there are two first rectangular teeth 110, and the first rectangular teeth 110 form a central angle of 90° in circumferential distribution on the hollow shaft tube.

(17) In another example, the other end of the universal joint 300 is connected to a gearbox or a main reducer.

(18) In a specific preparation process, the structure relates to a nesting-meshing composite connection structure between a hollow shaft tube and steel universal joints at two ends. The nesting-meshing composite connection structure is formed by connecting a CFRP drive shaft-tube joint to the steel universal joints at two ends. The bending resistance and torsion resistance of the lightweight CFRP drive shaft-tube joint of the automobile are achieved, and the problem of poor bending and torsion resistance of the existing dissimilar material connection structure between the hollow shaft tube and the steel universal joints is solved. According to the requirement for the torque to be transmitted, first a CFRP drive shaft tube with a certain outer diameter and wall thickness is selected, and when the shaft tube is formed, carbon fibers are distributed at 0°, ±45° and 90° with the axis, so that the CFRP drive shaft tube bears greater torque. At both ends of the hollow shaft tube, the outer diameter wall thickness t is cut by a certain thickness (e.g., 40% t-80% t) to obtain a 5-100 mm thin tube section (namely the shaft-tube joint 200) by axial machining, then machining is performed at the ends to obtain 2-6 uniformly and circumferentially distributed first rectangular teeth 110, and the first rectangular teeth 110 each have a thickness of 3-30 mm With respect to the tubular structures of the steel universal joints 300 matched with the hollow shaft tube at both ends, the inner diameters are enlarged to be the same as the outer diameter and length of the CFRP shaft joint 200, so that the steel universal joints are matched and sleeved with the shaft-tube joint 200 of the drive shaft. Similarly, 2-6 uniformly and circumferentially distributed second rectangular teeth are obtained by machining at the outer ends of the tubular structures of the universal joints 300, so that the second rectangular teeth are meshed with the first rectangular teeth of the shaft tube of the drive shaft, and it is ensured that the universal joint fork at both ends are in the same plane. Then, the CFRP shaft-tube joint is connected to steel universal joints at both ends by structural adhesive, and a nesting-meshing composite connection structure is formed after curing to obtain the CFRP drive shaft. The joint connection structure can bear enough torque and resist a certain bending load, and can avoid joint failure caused by different thermal expansion coefficients of steel and CFRP when the use environment temperature changes.

(19) In a specific example, it is determined that the CFRP shaft tube 100 is 1228 mm long, 79 mm in inner diameter and 89 mm in outer diameter, i.e., 5 mm in wall thickness, according to the transmitted torque and the space distance. The layer solution of the shaft tube is to lay 32 layers of CFRP One-way belt according to the sequence and angle in Table 1. The shaft tube is manufactured by a hot pressing curing molding process.

(20) TABLE-US-00001 TABLE 1 Laying sequence and fiber arrangement direction of the hollow shaft tube Sequence Fiber Sequence Fiber Sequence Fiber Sequence Fiber number angle number angle number angle number angle 1    0°  9   45° 17   90° 25 −45° 2   45° 10 −45° 18 −45° 26   45° 3 −45° 11   45° 19   45° 27   90° 4   45° 12 −45° 20    0° 28 −45° 5 −45° 13    0° 21 −45° 29   45° 6   90° 14   45° 22   45° 30 −45° 7   45° 15 −45° 23 −45° 31   45° 8 −45° 16   90  24   45° 32    0°

(21) The outer walls of both ends of the hollow shaft tube 100 are radially thinned by 3 mm, and the thinned length is 50 mm from the end in the axial direction, but two symmetrically distributed first rectangular teeth are reserved, thus the shaft-tube joint 200 is obtained. The first rectangular teeth form an angle of 90° in circumferential distribution the shaft tube, and each has a thickness of 3 mm and a length of 20 mm. A dedendum angle and an addendum angle are rounded with a fillet radius of 2 mm to form a joint structure of the CFRP drive shaft.

(22) An inner cavity material of the steel universal joint is cut, so that its diameter is the same as the outer diameter of the shaft-tube joint 200, and two second rectangular teeth which are uniformly and symmetrically distributed are obtained by cutting similarly. The second rectangular teeth form an angle of 90° in circumferential distribution, and each has a thickness of 3 mm and a length of 20 mm A dedendum angle and an addendum angle are rounded with a fillet radius of 2 mm.

(23) The shaft-tube joints 200 at both ends of the hollow shaft tube 100 are ground, then the positions where the outer circumferential surfaces of the shaft-tube joints 200 and the end faces and side faces of the first rectangular teeth and the steel universal joint are nested with each other are coated with structural adhesive, and then the shaft-tube joints 200 are inserted in inner cavities of the steel universal joint and just nested with the inner cavities. Two first rectangular teeth on the hollow shaft tube 100 and splines of two second rectangular teeth on the universal joint are meshed with each other respectively to form a nesting-meshing composite connection structure of the CFRP drive shaft tube and the steel universal joint, thus obtaining the CFRP automobile drive shaft for automobile power transmission.

(24) In order to further verify the performance effect of the shaft-tube joint structure of the drive shaft according to the present invention, laboratory performance tests are carried out:

(25) Beneficial Effects of Light Weight:

(26) Research by the International Aluminum Institute shows that for every 10% reduction in vehicle weight, fuel consumption can be reduced by 6%-8%, emissions can be reduced by 4%-6%, the 0-100 km acceleration capability of an automobile can be increased by 8%-10%, a braking distance can be shortened by 2-7 m, and the tire life can be increased by 7%. For every 100 kg reduction of automobile translation parts, 0.3-0.5 L of fuel can be saved per 100 km, and the carbon dioxide emission can be reduced by 800-1100 g. The energy-saving and emission-reducing effect of the drive shaft as an automobile rotating part is more obvious than that of the translation part by 6 times. The weight of the CFRP drive shaft of the present invention is 11.55 kg and is reduced by 9.66 kg compared with that of the steel drive shaft with the same structure, which is 21.21 kg. The CFRP drive shaft can save 0.174-0.290 L of oil and reduce carbon dioxide emission by 463.68-637.56 g as an automobile rotating part for every 100 km.

(27) VonMises Stress Performance at the Joint:

(28) As shown in FIG. 4, in the specific example, under the rated torque 7219 N.Math.m of the CFRP drive shaft, the maximum vonMises stress simulation value σ.sub.max at the joint is equal to 236.1 MPa. Considering the safety factor of 1.5 according to the automotive industry standard QC/T29082-1992, it can be seen that 1.5σ.sub.max=354.15 Mpa is smaller than the yield stress of the universal joint fork material, i.e., the CFRP drive shaft of the present invention meets structural strength requirement.

(29) Modal Performance:

(30) As shown in FIG. 5, in the specific example, the CFRP drive shaft is applied to an engine with a rated rotation speed of 2100 rpm, and its maximum rotation frequency is calculated as 44.7 Hz when the transmission ratio is 0.783. Modal analysis of the CFRP drive shaft shows that its first-order natural frequency is 96.7 Hz. Considering the safety factor of 0.7, 0.7*96.7 Hz=67.7 Hz>44.7 Hz, the first-order natural frequency of the drive shaft is much larger than its rotation frequency, that is, the drive shaft will not resonate and can rotate smoothly at the rated speed of the engine.

(31) Failure Index of the Composite Shaft Tube:

(32) As shown in FIG. 6, the failure index of the CFRP shaft tube is subjected to simulation calculation in the specific example, and its maximum failure index is 0.6038, and the reliability reaches 0.999 when the safety factor of the CFRP is 1.6. Therefore, it is verified that 1.6×0.6038=0.966<1 (when the failure index of the composite is less than 1, it can be considered as being safe and reliable), i.e., the CFRP shaft tube of the present invention meets the performance requirements.

(33) Although the implementation solution of the present invention has been disclosed above, it is not limited to the application listed in the specification and the implementation, it can be fully applied to various fields suitable for the present invention, and additional modifications can be easily implemented by those skilled in the art. Therefore, the present invention is not limited to the specific details and illustrations shown and described herein without departing from the general concept defined by the claims and the equivalent scope.