Torque transmission parts

Abstract

To provide a torque transmission component that has a retaining structure and can suppress deterioration of assembly ease. [Solution] A torque transmission component 10, wherein (a) the intermediate shaft 30, which is a first component, is cylindrical with an axis CL as its center, and has a hole 32e that opens toward the drive shaft 50 side in the direction of the axis CL and has a bottom, (b) the drive shaft 50, which is a second component, has a cylindrical projection 52 that protrudes toward the intermediate shaft 30 side in the direction of the axis CL, (c) the inner diameter Di of the hole 32e is larger than the outer diameter Do of the projection 52, (d) the difference ΔD between the inner diameter Di of the hole 32e and the outer diameter Do of the projection 52 is smaller than a predetermined dimensional difference ΔD_pred, and (e) the intermediate shaft 30 and the drive shaft 50 are connected with the projection 52 inserted into the hole 32e and grease 70 filled between the inner circumferential surface 32i of the hole 32e and the outer circumferential surface 56o of the projection 52.

Description

Technical Field

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[0001] The present invention relates to a torque transmission component that includes a first member and a second member and transmits torque between the first member and the second member.

Background Art

[0002] In a torque transmission component that connects a drive shaft and a differential gear in a vehicle, it is known to use a snap ring for anti-loosening. For example, the torque transmission component described in Patent Document 1 is such a component. The snap ring is fitted into a groove provided on the outer peripheral surface of the drive shaft. A gap is formed between the snap ring and the side surface of the groove so as not to prevent the diameter of the snap ring from expanding or contracting. Further, Patent Document 2 discloses that by injecting grease into the groove into which the snap ring is fitted, centering of the snap ring is performed to improve the assemblability of the drive shaft. "Centering" is an operation required when assembling members attached to various devices, and is to adjust the position or perform positioning so that the connecting portions are coaxial.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the torque transmission component described in Patent Document 1, the diameter of the snap ring expands when assembling the drive shaft to the differential gear, resulting in poor assembly. Furthermore, when inserting the drive shaft into the differential gear, the snap ring comes into contact with the mating portion of the differential gear, making work difficult, and there is a risk that the snap ring may break or fall off and remain inside the differential gear as foreign matter.

[0005] The present invention was made against the above circumstances, and its objective is to provide a torque transmission component that has a retaining structure and can suppress deterioration of assembly ease. [Means for solving the problem]

[0006] The gist of the present invention is a torque transmission component comprising a first member and a second member, for transmitting torque between the first member and the second member, wherein (a) the first member is cylindrical with an axis, and has a hole that opens toward the second member in the axial direction and has a bottom; (b) the second member has a cylindrical projection that protrudes toward the first member in the axial direction; (c) the inner diameter of the hole is larger than the outer diameter of the projection; (d) the difference between the inner diameter of the hole and the outer diameter of the projection is smaller than a predetermined dimensional difference; and (e) the first member and the second member are connected in a state where the projection is inserted into the hole and grease is filled between the inner circumferential surface of the hole and the outer circumferential surface of the projection. [Effects of the Invention]

[0007] According to the torque transmission component of the present invention, (a) the first member is cylindrical with an axis and has a hole that opens toward the second member in the axial direction and has a bottom; (b) the second member has a cylindrical projection that protrudes toward the first member in the axial direction; (c) the inner diameter of the hole is larger than the outer diameter of the projection; (d) the difference between the inner diameter of the hole and the outer diameter of the projection is smaller than a predetermined dimensional difference; and (e) the first member and the second member are connected with the projection inserted into the hole and grease filled between the inner circumferential surface of the hole and the outer circumferential surface of the projection. In this way, since the first member and the second member are connected with grease filled between the inner circumferential surface of the hole and the outer circumferential surface of the projection, a sealed space is formed inside the hole. When the second member tries to move out of the first member in the axial direction, the sealed space becomes a negative pressure lower than atmospheric pressure. This negative pressure prevents the second member from detaching axially from the first member. As a result, it becomes unnecessary to employ a retaining structure such as a snap ring or a bolt and nut fastening to prevent the second member from detaching axially from the first member. [Brief explanation of the drawing]

[0008] [Figure 1] This figure illustrates the state immediately before the start of assembly of the drive shaft to the intermediate shaft in a torque transmission component according to an embodiment of the present invention. [Figure 2] Figure 1 illustrates the intermediate stage of assembling the drive shaft to the intermediate shaft in the torque transmission component shown. [Figure 3] This diagram illustrates the state of the torque transmission component shown in Figure 1 after the drive shaft has been assembled to the intermediate shaft. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the embodiments, the drawings have been simplified or modified as appropriate, and the dimensional ratios and shapes of each part are not necessarily depicted accurately. [Examples]

[0010] Figure 1 is a diagram illustrating the state of the torque transmission component 10 according to an embodiment of the present invention, immediately before the start of assembly of the drive shaft 50 to the intermediate shaft 30.

[0011] The torque transmission component 10 comprises an intermediate shaft 30 and a drive shaft 50. In the state after the drive shaft 50 is assembled to the intermediate shaft 30, the torque transmission component 10 is a component that transmits torque from one of the intermediate shaft 30 and the drive shaft 50 to the other. The "intermediate shaft 30" and the "drive shaft 50" correspond to the "first component" and the "second component" in the present invention, respectively.

[0012] The intermediate shaft 30 is cylindrical with respect to the axis CL. The intermediate shaft 30 has a cylindrical shaft portion 32 on one end 30t side in the direction of the axis CL, and a cylindrical shaft portion 34 on the other end side opposite to the one end 30t side in the direction of the axis CL. Between the shaft portion 32 and the shaft portion 34 there is an inner wall 36 that divides their inner circumferences. As a result, the shaft portion 32 has a hole portion 32e that opens toward the one end 30t side in the direction of the axis CL and has a bottom. "One end 30t side" corresponds to the drive shaft 50 side in the direction of the axis CL, that is, the "second member side" in this invention. The inner circumferential surface 32i of the one end 30t side (opening side) of the shaft portion 32 in the direction of the axis CL is circular with respect to the axis CL and has an inner diameter Di [m]. The inner diameter Di is also the inner diameter of the hole portion 32e. A fitting portion 32s is provided on the inner circumferential surface 32i of the shaft portion 32 on the side opposite to the end 30t in the axial direction CL (the side facing the inner wall 36). The fitting portion 32s is, for example, an inner circumferential tooth that is spline-fitted. For example, in the axial direction CL, the other end of the shaft portion 34 opposite to the shaft portion 32 is connected to a side gear of a differential gear (not shown).

[0013] The drive shaft 50 comprises a cylindrical shaft portion 58 centered on the axis CL, and a cylindrical projection portion 52 projecting from the shaft portion 58 toward one end 50t on the axis CL. "One end 50t side" corresponds to the intermediate shaft 30 side in the direction of the axis CL, that is, the "first member side" in this invention. The shaft portion 58 has a larger diameter than the projection portion 52. The projection portion 52 comprises a first shaft portion 54 located toward one end 50t in the direction of the axis CL, and a second shaft portion 56 located opposite to one end 50t in the direction of the axis CL. The outer circumferential surface 54o of the first shaft portion 54 is provided with a fitting portion 54s that can be fitted with the fitting portion 32s of the intermediate shaft 30. The fitting portion 54s is, for example, an outer tooth that is spline fitted. The outer circumferential surface 56o of the second shaft portion 56 is circular centered on the axis CL and has an outer diameter Do [m]. The outer diameter Do is also the outer diameter of the protrusion 52. The outer circumferential surface 56o corresponds to the "outer circumferential surface of the protrusion" in this invention.

[0014] The inner diameter Di is larger than the outer diameter Do, but the difference ΔD (=Di-Do) between the inner diameter Di and the outer diameter Do is smaller than a predetermined dimensional difference ΔD_pred[m]. The predetermined dimensional difference ΔD_pred is a dimensional difference that is experimentally or design-predetermined so that assembly is within an acceptable range and the sealed space described later can maintain a negative pressure lower than atmospheric pressure.

[0015] The outer circumferential surface 56o of the second shaft portion 56 is provided with a groove 56d extending from one end 50t to the opposite end. The groove 56d has a groove width direction that is circumferential and a depth direction that is toward the inner circumference. For example, the center line of the groove 56d in the groove width direction extends in the direction of the axis CL. The groove width of the groove 56d gradually narrows from one end 50t to the opposite end in the direction of the axis CL.

[0016] Before assembling the drive shaft 50 to the intermediate shaft 30, grease 70 is applied to the outer circumferential surface 56o of the second shaft portion 56. Grease 70 is a high-viscosity lubricant.

[0017] FIG. 2 is a diagram for explaining a state in an intermediate stage of assembling the drive shaft 50 to the intermediate shaft 30 in the torque transmission component 10 shown in FIG. 1. FIG. 2 shows a state at the time when the fitting of the fitting portion 54s to the fitting portion 32s is started and the insertion into the hole portion 32e of the second shaft portion 56 is started.

[0018] There is a gap extending in the axial direction of the axis CL between the fitting portion 32s and the fitting portion 54s. Therefore, when the drive shaft 50 is inserted into the hole portion 32e of the intermediate shaft 30, the air in the hole portion 32e is discharged in the direction of arrow A via the groove portion 56d. In this case, the air in the hole portion 32e is discharged while pushing aside the grease 70. Note that the air easily flows in the direction from one end portion side 50t in the axial direction of the axis CL toward the opposite side in the groove portion 56d, while the air hardly flows in the opposite direction.

[0019] FIG. 3 is a diagram for explaining a state after the assembly of the drive shaft 50 to the intermediate shaft 30 in the torque transmission component 10 shown in FIG. 1 is completed.

[0020] In the state of FIG. 3, the fitting portion 32s and the fitting portion 54s are in a fitted state. That is, the intermediate shaft 30 and the drive shaft 50 are connected in a non-rotatable relative state. Also, a part of the air in the hole portion 32e has been discharged via the groove portion 56d according to the volume of the protruding portion 52 inserted into the hole portion 32e. In this state, the outer peripheral surface 56o of the second shaft portion 56 and the inner peripheral surface 32i of the hole portion 32e facing it are filled with the grease 70. Note that after the air is discharged via the groove portion 56d, the groove portion 56d is again filled with the grease 70. Thus, the hole portion 32e is a sealed space whose opening is sealed by the protruding portion 52 and the grease 70. The pressure in the sealed space is the same as the atmospheric pressure.

[0021] In the state of FIG. 3, when the drive shaft 50 tends to come out from the intermediate shaft 30 in the direction of the axis CL, the sealed space is enlarged while maintaining the sealed state. As a result, the pressure in the sealed space becomes a negative pressure lower than the atmospheric pressure. This negative pressure suppresses the drive shaft 50 from coming out from the intermediate shaft 30 in the direction of the axis CL.

[0022] According to the present embodiment, (a) the intermediate shaft 30 is cylindrical with the axis CL as the center, and has a hole 32e that opens toward the drive shaft 50 side in the direction of the axis CL and has a bottom, (b) the drive shaft 50 has a columnar protrusion 52 that protrudes toward the intermediate shaft 30 side in the direction of the axis CL, (c) the inner diameter Di of the hole 32e is larger than the outer diameter Do of the protrusion 52, (d) the difference ΔD between the inner diameter Di of the hole 32e and the outer diameter Do of the protrusion 52 is smaller than a predetermined dimensional difference ΔD_pred, and (e) the intermediate shaft 30 and the drive shaft 50 are connected in a state where the protrusion 52 is inserted into the hole 32e and grease 70 is filled between the inner peripheral surface 32i of the hole 32e and the outer peripheral surface 56o of the protrusion 52. Thus, since the intermediate shaft 30 and the drive shaft 50 are connected in a state where the grease 70 is filled between the inner peripheral surface 32i of the hole 32e and the outer peripheral surface 56o of the protrusion 52, a sealed space is formed in the hole 32e. When the drive shaft 50 tends to come out from the intermediate shaft 30 in the direction of the axis CL, the sealed space becomes a negative pressure lower than the atmospheric pressure. This negative pressure suppresses the drive shaft 50 from coming out from the intermediate shaft 30 in the direction of the axis CL. For example, in order to suppress the drive shaft 50 from coming out from the intermediate shaft 30 in the direction of the axis CL, it is not always necessary to adopt a retaining structure using a snap ring or a retaining structure by fastening bolts and nuts.

[0023] Note that what has been described above are embodiments of the present invention, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art without departing from the gist thereof.

[0024] In the embodiments described above, the intermediate shaft 30 and the drive shaft 50 corresponded to the "first member" and "second member" in the present invention, respectively, but the present invention is not limited to this embodiment. The present invention is applicable to various forms of torque transmission components that transmit torque. [Explanation of symbols]

[0025] 10: Torque transmission component, 30: Intermediate shaft (first member), 32e: Hole, 32i: Inner circumferential surface, 50: Drive shaft (second member), 52: Protrusion, 56o: Outer circumferential surface (outer circumferential surface of the protrusion), 70: Grease, CL: Axis, Di: Inner diameter (inner diameter of the hole), Do: Outer diameter (outer diameter of the protrusion), ΔD_pred: Specified dimensional difference

Claims

[Claim 1] A torque transmission component comprising a first member and a second member, which transmits torque between the first member and the second member, The first member is cylindrical with respect to its axis and has a hole that opens toward the second member in the axial direction and has a bottom. The second member has a cylindrical projection that protrudes toward the first member in the axial direction, The inner diameter of the hole is larger than the outer diameter of the protrusion. The difference between the inner diameter of the hole and the outer diameter of the protrusion is smaller than a predetermined dimensional difference. The first member and the second member are connected with the protruding portion inserted into the hole and grease filled between the inner circumferential surface of the hole and the outer circumferential surface of the protruding portion. Torque transmission components.

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