JP2011225086A - Axle housing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an axle housing structure capable of effectively improving acoustic characteristics and workability while achieving weight reduction.SOLUTION: In an axle housing 10 for housing a differential gear unit 100, the differential gear unit 100 and the axle housing 10 are interconnected through a reinforcing member 15. One end of the reinforcing member 15 is connected to a differential cap 14 of the differential gear unit 100, and the other end of the reinforcing member 15 is connected to a housing surface of the axle housing 10.

Description

  The present invention relates to a structure of an axle housing (axle case) that is a part of a suspension of a front wheel or a rear wheel of an automobile and accommodates a drive axle, a differential gear unit, and the like.

  The axle housing contains a differential gear, a drive shaft (drive shaft), and lubricating oil, and functions as a suspension component. Therefore, it has both the role as a differential gear case and the role of supporting the vehicle as a suspension member. First, in the characteristic as a differential gear case, since a differential gear is provided inside, the characteristic that the sound generated by the differential gear is not leaked to the outside or the vibration (noise) of the differential gear is not amplified is required.

  However, the axle housing has a specific shape or form, and in particular, a relatively large surface is formed on the rear side of the vehicle. The surface easily vibrates, and resonance that causes a peak in vibration at a specific frequency is likely to occur. As a cause of noise, the vibration generated by the engagement of the differential gear is used as the main sound source. However, if the resonance frequency of the axle housing and a multiple of the differential gear engagement frequency overlap, the sound of a specific frequency becomes remarkably loud. In other words, the noise has a frequency peak, which is very uncomfortable in terms of audibility, and has a great influence on the quality of the vehicle, particularly in terms of noise.

  The noise problem can be improved mainly by making it difficult for the rear surface of the axle housing to vibrate. That is, generally, increasing the plate thickness increases the rigidity of such a surface and makes it difficult to vibrate.

  On the other hand, the axle housing is a suspension member, and since this becomes an unsprung weight, there is a demand for weight reduction. However, if the plate thickness is reduced in order to reduce the weight, the rigidity of the surface is lowered and the vibration is likely to occur, and the audible characteristics (acoustic characteristics) are deteriorated. In other words, it is extremely difficult to satisfy the weight reduction and the acoustic characteristics at the same time.

  From the viewpoint of weight reduction, the integral molding capable of eliminating the welded portion is an extremely effective means. In that case, in the conventional axle housing described in Patent Document 1, for example, the boundary portion between the right and left straight pipe portions and the housing center A metal annular member is fitted to the base plate, and noise due to vibration in the vicinity thereof is to be suppressed.

JP 2006-213178 A

However, the method shown in Patent Document 1 has an opening for accommodating the differential gear on the front side of the vehicle on the rear surface of the housing center, which is the most acoustically problematic, so that it is extremely difficult to install the annular member. . Even if the annular member is extended and enlarged from the boundary toward the center of the housing center, an opening for inserting the differential gear must be provided, resulting in a significant decrease in the rigidity of the annular member. However, it becomes difficult to suppress vibration. Further, from the viewpoint of vibration suppression, a method of increasing the plate thickness of a large vibration surface can be considered, and for this purpose, a method of manufacturing an axle housing by a casting method can be considered, but the thickness is several mm or less. In the case of the plate thickness, molding by casting is substantially difficult, and thus plastic processing is unavoidable. However, in the sheet metal processing, it is difficult to make a specific part (near the center part of the axle housing) a desired thickness, and it is extremely difficult to improve acoustic characteristics by the plate thickness.
In addition, there is a method of additionally installing a reinforcing member or the like inside the axle housing by welding, but when the axle housing is integrally formed, it can be installed only from the opening side for incorporating the differential gear. For this reason, the direction of welding is limited, and assembling workability will be remarkably deteriorated as it is.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an axle housing structure that effectively improves acoustic characteristics, assembling workability, and the like while achieving weight reduction.

  An axle housing structure according to the present invention is an axle housing structure that accommodates a differential gear unit, and is characterized in that the differential gear unit and the axle housing are connected via a reinforcing member.

In the axle housing structure according to the present invention, one end of the reinforcing member is coupled to a differential cap of the differential unit, and the other end of the reinforcing member is coupled to a housing surface of the axle housing.
The axle housing structure according to the present invention is characterized in that at least two reinforcing members are arranged at a substantially central portion of the axle housing.
In the axle housing structure according to the present invention, the axle housing is integrally formed.

  According to the present invention, it is possible to arrange the reinforcing member at a portion where the vibration suppressing effect is greatest in the axle housing, thereby greatly improving the acoustic characteristics. Further, since this reinforcing member can be fixed from the outside of the axle housing, good assembling workability can be obtained.

1 is a schematic perspective view showing an embodiment of an axle housing structure according to the present invention. It is a partially broken perspective view which shows embodiment of the axle housing structure by this invention. It is a top view which shows embodiment of the axle housing structure by this invention. It is a top view which shows typically the principal part structure of the differential gear unit which concerns on the axle housing structure by this invention. It is a figure which shows the specific structural example around the rod in embodiment of the axle housing structure by this invention. It is the A section enlarged view of FIG. It is the figure which shows the specific structural example around the rod in the deformation | transformation of the axle housing structure by this invention, and its enlarged view.

Hereinafter, preferred embodiments of an axle housing structure according to the present invention will be described with reference to the drawings.
FIG. 1 shows an example of an axle housing 10 according to an embodiment of the present invention. First, an outline of an axle housing 10 to which the present invention is applied will be described. Here, for example, it is an example of a rear-wheel drive vehicle, and typically, the output of an engine mounted on the front portion of the vehicle is transmitted to the rear wheels via a propeller shaft. In the drawings used in the following description, the front of the vehicle is indicated by an arrow Fr, the rear of the vehicle is indicated by an arrow Rr, and the lateral right side of the vehicle is indicated by an arrow R, if necessary. Is indicated by an arrow L.
In this specification, descriptions such as up and down, front and rear, and left and right indicate directions and positional relationships based on the body of a general FR vehicle, that is, a rear wheel drive vehicle in which an engine is mounted on the front. Therefore, the axial direction means the axial direction of the axle housing and is substantially the same as the vehicle body width direction. When an axle housing is mounted on the front of a four-wheel drive vehicle or the like, the front-rear relationship is reversed. In the present specification and drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 1, the axle housing 10 is disposed in the left-right direction, and the shaft straight pipe portion 10 </ b> B extends on both the left and right sides of the center portion 10 </ b> A (center portion). The center portion 10A has an expanded form as a whole as shown in the figure, and the differential gear unit 100 is accommodated in the center portion 10A as shown in FIG.

  Here, the differential gear unit 100 will be schematically described with reference to FIG. FIG. 4 (plan view) schematically shows a main part configuration of the differential gear unit 100. Although a detailed description of a specific structure related to the method of supporting the differential gear unit 100 and the like is omitted here, the differential gear unit 100 includes a drive gear 101, a ring gear 102, a pinion gear 103, and a side gear 104. First, the propeller shaft 1 extends rearward from an engine mounted on the front of the vehicle via a transmission or the like, and the propeller shaft 1 is coupled to the drive gear 101. The drive gear 101 meshes with the ring gear 102 and rotationally drives it.

  A pair of pinion gears 103 are rotatably supported on the ring gear 102, and these pinion gears 103 mesh with a pair of left and right side gears 104, respectively. The left and right axles 2 are coupled to the side gears 104, and the left and right wheels 3 (rear wheels) are coupled to the axles 2, respectively. The left and right axles 2 are rotated through the differential gear unit 100 by the rotation of the propeller shaft 1, thereby driving the wheels 3 to rotate.

  Since the axle housing 10 accommodates the differential gear unit 100 and transmits the engine power to the wheels 3 via the differential gear unit 100, high rigidity and strength are required. In addition, as described above, good acoustic characteristics are required in terms of quality in relation to the operation sound and the like.

  In this embodiment, the axle housing 10 can be integrally formed by hydroforming, and the forming method will be schematically described here. In hydroforming, a metal pipe is sandwiched between an upper mold and a lower mold, and a working fluid is injected into the metal pipe to fill it. After the working fluid is filled, the metal element tube is pushed in the axial direction from the end of the metal element tube to the center by the axial pushing cylinder head while applying pressure in the metal element tube, so that the metal element tube has a desired shape, that is, an axle housing shape. Finish.

  3 and the like, an opening (not shown) is formed on the front side of the center portion 10A of the axle housing 10, and the differential gear unit 100 is incorporated into the axle housing 10 through this opening. It has become. A ring-shaped flange 11 is fixed around the opening, and a base 13 is fixed to the flange 11 by a plurality of bolts 12. A pair of differential caps 14 spaced apart on the left and right are attached to the base 13 side, and the inner ends of the left and right axles 2 are rotatably supported by the differential caps 14. The differential gear unit 100 is disposed inside the left and right differential caps 14.

  Now, particularly in the present invention, the differential gear unit 100 and the axle housing 10 are connected via a reinforcing member. In this embodiment, as shown in FIGS. 2 and 3, the rod 15 is provided as a reinforcing member, and the rod 15 is interposed between the left and right differential caps 14 and the housing surface (inner surface) of the axle housing 10. It has a connection structure. In this example, two rods 15 are arranged.

  5 and 6 show specific configuration examples around the rod 15. The rod 15 may typically be a cylindrical member, one end of which is coupled to the differential cap 14 and the other end is coupled to the housing surface of the axle housing 10. Here, the differential cap 14 is divided into two parts by a base part 14A protruding from the base 13 (on the rear side of the vehicle in the actual vehicle) and an upper half part 14B joined so as to overlap the base part 14A. The pair of bolts 16 are fastened and fixed to each other.

  In this case, a screw portion 17 (male screw) is formed on one end side of the rod 15, and a screw portion 18 (female screw) to which the screw portion 17 is screwed is formed in the center portion of the upper half portion 14B. In addition, you may provide the seat part 19 protruded in the boss shape around the screw part 18. FIG. A screw portion 20 (female screw) is formed on the other end side of the rod 15, and a bolt 21 is screwed to the screw portion 20 from the outside of the axle housing 10. It is assumed that the axle housing 10 has an insertion hole (not shown) through which the bolt 21 is inserted. A washer 22 is mounted between the bolt 21 (bolt head) and the axle housing 10.

  In the axle housing structure of the present invention, when the differential gear unit 100 or the like is assembled, the differential cap 14 and the differential gear unit 100 are first supported on the base 13 in a united state and formed on the front side of the axle housing 10. It is incorporated into the axle housing 10 through the opened opening. At that time, the screw portion 17 of the rod 15 is screwed to the screw portion 18 to be attached to the upper half portion 14B of the differential cap 14 in advance. By screwing a bolt 21 from the outside of the axle housing 10 to the threaded portion 20 of the rod 15 disposed inside the axle housing 10, the gap between the differential gear unit 100 and the axle housing 10 is shown in FIG. Are connected via a rod 15 as a reinforcing member.

  As described above, the rod 15 as a reinforcing member is arranged inside the axle housing 10, and thereby the rear surface of the axle housing 10 is fixed, and particularly, the rear surface vibration can be effectively suppressed. And, by the effect of suppressing the surface vibration, the acoustic characteristics can be greatly improved by lowering the noise peak or shifting the frequency. In this case, the installation site of the rod 15 is set in a space between the rear surface of the axle housing 10 and the differential gear unit 100. That is, a high vibration suppression effect can be obtained by applying it to a portion having the largest vibration suppression effect.

  Further, the rod 15 is finally disposed inside the axle housing 10, and is fixed by a bolt 21 from the outer rear side of the axle housing 10. Thus, since it can fix from the outer side of the axle housing 10, favorable assembly workability | operativity is obtained. For example, when it is fixed inside the axle housing 10 by welding or the like, workability is inevitably deteriorated in terms of space and welding direction.

  Here, in a specific application example of the present invention, first, when the rod 15 is not provided, vibration analysis was performed by modal analysis of the axle housing 10. As a result of the analysis, it was found that the rear portion of the axle housing 10 corresponding to the differential cap 14 vibrates in the vicinity of 650 Hz. On the other hand, according to the axle housing structure of the present invention in which the rod 15 is installed, noise having a peak near 650 Hz when traveling at 80 to 100 km / h could be improved by 2 dB or more.

  Furthermore, FIG. 7 shows a modification of the present invention. In this example, the rods 23 are disposed at corresponding positions of the bolts 16 for fastening the base portion 14A and the upper half portion 14B of the differential cap 14, respectively. The rod 23 also has a fastening function of the bolt 16, that is, a screw portion 24 (male screw) is formed at the tip of one end side thereof, while a screw portion 25 (threaded portion 24) is screwed into the base portion 14 </ b> A. Female thread). Similarly to the rod 15, a screw portion 20 (female screw) is formed on the other end side of the rod 23, and a bolt 21 is screwed into the screw portion 20 from the outside of the axle housing 10. Note that a D-cut 26 or the like may be formed at a suitable position on the outer periphery of the rod 23, and rotational torque may be applied when the screw portion 24 is screwed using this portion.

As mentioned above, although this invention was demonstrated with various embodiment, this invention is not limited only to these embodiment, A change etc. are possible within the scope of the present invention.
As a fixing method of the rod 15, for example, a male screw is formed at one end and the other end of the rod 15, and the male screw is inserted from the inside of the axle housing 10 to the outside through a bolt insertion hole formed in the axle housing 10. Then, the rod 15 may be fixed by screwing a nut into the male screw protruding outward. In addition to the case of using bolts and nuts as in the above example, methods such as adhesion and caulking are also possible.

  Further, when the differential cap 14 is manufactured by casting or forging, it is possible to integrally form a portion or shape corresponding to the rod 15. In that case, the tip of the part may be penetrated from the inside of the axle housing 10 to the outside, and the tip may be crushed for caulking.

  Moreover, although the example which arrange | positions the rod 15 as a reinforcement member along the vehicle front-back direction was demonstrated, it is also possible to arrange | position with a moderate inclination angle in the left-right direction or the up-down direction with respect to the front-back direction, In any modified example including this case, substantially the same effect as the above embodiment can be obtained.

1 propeller shaft, 2 axles, 3 wheels, 10 axle housing, 10A center portion, 11 flange, 13 base, 14 differential cap, 15 rod (reinforcing member), 16 bolt, 17, 18, 20 screw portion, 21 bolt, 100 Differential gear unit, 101 drive gear, 102 ring gear, 103 pinion gear, 104 side gear.

Claims (4)

An axle housing structure for accommodating a differential gear unit,
An axle housing structure in which the differential gear unit and the axle housing are connected via a reinforcing member.   The axle housing structure according to claim 1, wherein one end of the reinforcing member is coupled to a differential cap of the differential unit, and the other end of the reinforcing member is coupled to a housing surface of the axle housing.   The axle housing structure according to claim 1 or 2, wherein at least two of the reinforcing members are arranged at a substantially central portion of the axle housing.   The axle housing structure according to any one of claims 1 to 3, wherein the axle housing is integrally formed.

Images