JP2007062493A - Drive shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress generation of spark at projection welding. <P>SOLUTION: The drive shaft 1 transmits engine propulsive force of an automobile to a wheel. A balance weight 5 is mounted to a predetermined part of an outer peripheral surface of the drive shaft 1 by projection welding. The balance weight has a projection part 5a for projection welding projected to a drive shaft side; and a body part 5b arranged between the outer peripheral surface of the drive shaft through a predetermined clearance h. An R chamfered part 5c for suppressing generation of spark is provided on an edge at a side opposed to the outer peripheral surface of the drive shaft on the body part 5b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a drive shaft that transmits a driving force of, for example, an automobile engine to wheels.

  The drive shaft (propeller shaft) that transmits the propulsive force of the automobile engine to the wheels rotates at a high speed, and thus vibration (rotation around the rotation) is likely to occur and accurate balance adjustment is required. For this reason, the drive shaft is usually subjected to unbalance correction. For this unbalance correction, a balance weight (balance tip) made of a press-formed product is used. The balance weight is welded to the outer peripheral surface of a cylindrical tube constituting the drive shaft. As this welding method, projection welding capable of multi-point welding at a time is used.

When performing projection welding, a projection for projection welding is provided on the balance weight, and the balance weight is pressed between the balance weight and the drive shaft while pressing the balance weight against the drive shaft with a predetermined pressure. Current is passed through. If it does in this way, an electric current and a pressure will concentrate on a convex part, and the said convex part and a drive shaft will be welded. In order to concentrate the current and pressure on the convex portion, the current flows with the contact portion between the balance weight and the drive shaft being only the convex portion (see Patent Document 1).
Japanese Utility Model Publication No. 5-94555

  During the above-described projection welding, a spark (spark) may fly between the edge of the balance weight facing the drive shaft and the outer peripheral surface of the drive shaft. Since this spark forms a minute recess on the surface of the drive shaft, the quality of the drive shaft is degraded. Moreover, since the electric current which should be concentrated on the convex part of a balance weight reduces by generation | occurrence | production of a spark, there exists a possibility that welding strength may fall.

  The present invention has been made in view of the above-described situation, and an object thereof is to suppress the occurrence of sparks during projection welding.

  The drive shaft of the present invention is a drive shaft in which a balance weight is attached to a part of the outer peripheral surface of the drive shaft by projection welding, and the balance weight is interposed between the outer peripheral surface of the drive shaft and a predetermined gap. And at least a part of an edge of the main body portion facing the outer peripheral surface of the drive shaft, and a projection welding projection protruding from the main body portion toward the drive shaft side. In addition, an R chamfering portion that suppresses the occurrence of sparks with the drive shaft is provided.

  The current is relatively concentrated on the edge portion of the balance weight main body, but by providing the R chamfered portion, the current concentration is mitigated and the occurrence of sparks is suppressed. The edge portion of the main body portion has a relatively large dimensional error (formation variation) due to press molding compared to the center side thereof, so that the separation distance (gap) from the surface of the drive shaft is more likely to approach the design value. However, the provision of the R chamfered portion at the edge increases the distance between the edge and the surface of the drive shaft, so that the occurrence of sparks is also suppressed from this viewpoint.

  Since the occurrence of sparks during projection welding is suppressed by the R chamfered portion provided at the edge of the balance weight, it is possible to prevent the quality of the drive shaft from being lowered and to prevent the welding strength from being lowered. be able to.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an overall view of a propeller shaft 1 for an automobile which is an embodiment of a drive shaft of the present invention.
The propeller shaft 1 has cross shaft joints 2 provided at both ends, and connecting portions 3 that connect the cross shaft joints 2 at both ends. The connecting portion 3 is provided with a tube 4 that is a cylindrical member. The tube 4 consists of a steel pipe, and the outer peripheral surface is a circumferential surface. Each cross joint 2 has two yokes 2b connected to a single cross shaft 2a in a swingable manner.

  A steel balance weight 5 for suppressing vibration during rotation of the propeller shaft 1 is attached to the tube 4 of the propeller shaft 1. The balance weight 5 is welded to the outer peripheral surface of the tube 4 by projection welding. The appropriate weight and attachment position of the balance weight 5 are calculated by a balancer that is a well-known measuring device.

  2 to 5 are views showing the balance weight 5, FIG. 2 is a plan view, FIG. 3 is a side view, FIG. 4 is a sectional view taken along the line AA in FIG. 2, and FIG. It is sectional drawing in a line. In FIG. 3, a cross-sectional view of the tube 4 to which the balance weight 5 is attached is indicated by phantom lines. As shown in FIGS. 2 and 3, the balance weight 5 includes a projection welding convex portion 5 a and a curved plate-like main body portion 5 b. The convex portions 5a and the main body portion 5b are integrally formed by pressing.

The main body 5 b has a shape along the outer peripheral surface of the tube 4 when attached to the tube 4. That is, the main body 5b is rectangular in plan view in FIG. 2, is curved with a constant curvature in the long side direction, and extends in parallel with the bus bar of the tube 4 in the short side direction. In the state of being attached to the tube 4, the curvature center of the main body 5 b is on the central axis of the tube 4. Further, corner chamfers 5d made of curved surfaces are formed at the four corners where the long side and the short side of the main body 5b intersect.
The main body 5 b is arranged so that its long side is parallel to the circumferential direction of the tube 4. Further, a gap h corresponding to the protruding length of the convex portion 5a is provided between the main body portion 5b and the outer peripheral surface of the tube 4 (see FIG. 3).

A pair of convex portions 5a of the balance weight 5 are provided at a predetermined interval in the long side direction. This convex part 5a protrudes toward the tube 4 side from the main-body part 5b (refer FIG.3 and FIG.5). The balance weight 5 is welded to the tube 4 by projection welding at the tip portion of the convex portion 5a. This projection welding is performed by flowing a welding current between the balance weight 5 and the tube 4 while pressing the balance weight 5 against the tube 4. When a welding current is passed while applying pressure, the welding current and the applied pressure are concentrated on the convex portion 5 a, and resistance heat is generated between the convex portion 5 a and the tube 4. Due to this resistance heat generation, a nugget (not shown) is formed between the convex portion 5 a and the tube 4.
As shown in FIG. 1, two balance weights 5 are attached to the propeller shaft 1 with a predetermined distance in the axial direction.

An R chamfered portion 5c is provided on the edge of the main body portion 5b facing the outer peripheral surface of the tube 4 (tube 4 side). The R chamfered portion 5c is provided over the entire periphery of the tube 4 side edge of the main body portion 5b. When the R chamfered portion 5c is not provided, a spark (spark) is likely to fly from the corner portion of the edge during projection welding. However, the provision of the R chamfered portion 5c effectively suppresses the occurrence of sparks (sparks).
The R chamfered portion 5c is formed simultaneously with the main body portion 5b and the convex portion 5a by pressing. For this reason, the manufacturing cost of the balance weight 5 is not increased by the R chamfered portion 5c. Further, the edge 5e opposite to the tube 4 side is not provided with an R chamfer (see FIGS. 3 and 4). Since the edge 5e is relatively far from the tube 4, it is not necessary to consider the occurrence of sparks from the edge 5e.

  There are two possible causes for the occurrence of the edge in the portion where spark is likely to occur. The first cause is that current tends to concentrate on the corners of the edge. The second cause is that the error of the gap h based on the dimensional error of the balance weight 5 becomes most obvious at the edge portion. That is, the press-molded rectangular balance weight 5 has the largest dimensional error at the edge portions at both ends in the longitudinal direction of the main body 5b. Therefore, when the R chamfer 5c is not provided (see the dotted line in FIG. 6), Due to this dimensional error, the edge portion is likely to be the narrowest gap h2 compared to the designed gap h1 (see FIG. 6).

  The R chamfered part effectively copes with the above two causes. Regarding the first cause, the R chamfered portion 5c eliminates the corner portion of the edge and relaxes the concentration of current on the edge, thereby suppressing the occurrence of sparks. Regarding the second cause, the R chamfered portion 5c makes the gap h3 between the edge and the tube 4 at both ends in the longitudinal direction of the main body portion 5b wider than the gap h2 when the R chamfered portion 5c is not provided. Suppresses the occurrence.

  As described above, according to the present embodiment, since it is possible to suppress the occurrence of spark between the balance weight 5 and the propeller shaft 1, it is possible to prevent the quality of the propeller shaft 1 from being deteriorated due to the spark. The Further, a decrease in welding current due to the occurrence of spark is suppressed, and the welding strength is improved.

  The R chamfered portion 5c only needs to be provided at least in a portion where the spark is easily generated in the edge of the main body portion 5b. Further, the present invention can be applied to various drive shafts such as a drive shaft for transmitting the power of a motor in addition to the above-described propeller shaft for an automobile.

It is a general view of the propeller shaft which is one Embodiment of this invention. It is a top view of a balance weight. It is a side view of a balance weight. It is sectional drawing of the short side direction of a balance weight. It is sectional drawing of the convex part vicinity in a balance weight. It is a side view for demonstrating the clearance gap between a balance weight and a tube.

Explanation of symbols

1 Propeller shaft (drive shaft)
5 Balance weight 5a Convex part 5b Body part 5c R chamfered part h Crevice

Claims (1)

A drive shaft having a balance weight attached to a part of the outer peripheral surface of the drive shaft by projection welding,
The balance weight has a main body portion disposed between the outer peripheral surface of the drive shaft via a predetermined gap, and a projection welding projection protruding from the main body portion toward the drive shaft side,
A drive shaft characterized in that an R chamfered portion that suppresses the occurrence of sparks with the drive shaft is provided on at least a part of an edge of the main body portion facing the outer peripheral surface of the drive shaft.

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