Abstract:
A stabilizer bar is intended for use in a vehicle, and a torsion part of the stabilizer bar is fixed to the vehicle body by a fixing member. A resin sheathing is provided integrally on an outer peripheral surface of the stabilizer bar. The fixing member is composed of the sheathing, a rubber bush disposed on the outer periphery of the sheathing, and a mounting fixture for mounting the rubber bush on the vehicle body side so as to cover the outer periphery of the rubber bush. The sheathing and the rubber bush are immovably assembled to each other. Thus, there may be provided a vehicle stabilizer, highly durable, easily mountable and replaceable, low-cost, and highly operable.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a Divisional of U.S. application Ser. No. 12/797,807, filed Jun. 10, 2010 now abandoned, which is a Continuation application of PCT Application No. PCT/JP2009/053616, filed Feb. 20, 2009, which was published under PCT Article 21(2) in English. 
     This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2008-040500, filed Feb. 21, 2008, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a vehicle stabilizer provided with a stabilizer bar. 
     2. Description of the Related Art 
     A vehicle stabilizer provided with a stabilizer bar connects the stabilizer bar to a suspension of a vehicle and stabilizes the attitude of the vehicle by utilizing a reaction force of the stabilizer bar. For example, the vehicle stabilizer is constructed so that opposite ends of the U-shaped stabilizer bar are coupled to operating parts of the suspension, and a torsion part of the stabilizer bar is fixed to a vehicle body by a fixing member and serves to receive a torsional reaction force. 
     Conventionally, a rubber bush is used for the fixing member to fix the torsion part of the stabilizer bar to the vehicle body frame. Specifically, the rubber bush is provided with a hole portion through which the stabilizer bar is passed and a notch for opening the hole portion. The notch is opened in assembling the rubber bush to the stabilizer, and the rubber bush is attached to the vehicle body frame by means of bolts or the like with the aid of, for example, a U-shaped mounting fixture. 
     Also known is an example in which a rubber bush is fixed to a stabilizer bar with an adhesive agent or by vulcanization molding or the like. In the case of this rubber bush, no gap is formed between the stabilizer bar and the rubber bush. If a torsional motion acts on the stabilizer bar as the suspension moves up and down, the rubber bush is deformed correspondingly. Thus, functions and effects for the stabilizer can be obtained by the deformation of the rubber bush as well as by a torsional action of the torsion part. 
     [Patent Document 1] Jpn. Pat. Appln. KOKAI Publication No. 2006-27311 
     However, the fixing member configured so that the stabilizer bar is passed through the hole portion of the rubber bush and fixed to the frame by means of the mounting fixture cannot fully restrain the movement of the stabilizer bar. 
     In some cases, therefore, the stabilizer bar may rotate around its axis or move axially with respect to the rubber bush. Thereupon, a noise may be produced by the stabilizer bar and the rubber bush that rub against each other, and the stabilizing effect of the stabilizer may vary. 
     Further, fixing the rubber bush to the stabilizer bar requires, for example, a process for holding them in a heating furnace for a long time and entails a high cost. In replacing the rubber bush, moreover, the rubber bush must be removed from the stabilizer bar by cutting, melting, or some other operation. In addition, a new rubber bush must be fixed to the stabilizer bar with an adhesive agent or by vulcanization molding or the like, thus the replacement of the rubber bush requires much labor. 
     BRIEF SUMMARY OF THE INVENTION 
     A fixing member for fixing a torsion part of a stabilizer bar of the vehicle stabilizer to a vehicle body is composed of a sheathing provided integrally on an outer surface of the stabilizer bar, a rubber bush disposed on the outer periphery of the sheathing, and a mounting fixture for mounting the rubber bush on the vehicle body so as to cover the outer periphery of the rubber bush. The sheathing and the rubber bush are immovably assembled to each other. 
     Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention. 
         FIG. 1  is a perspective view showing one embodiment of a stabilizer according to the present invention; 
         FIG. 2  is a perspective view showing a fixing member of the stabilizer shown in  FIG. 1 ; 
         FIG. 3  is a perspective view showing a mounting fixture of the stabilizer shown in  FIG. 1 ; 
         FIG. 4  is a perspective view showing a rubber bush of the stabilizer shown in  FIG. 1 ; 
         FIG. 5  is a perspective view showing a sheathing of the stabilizer shown in  FIG. 1 ; 
         FIG. 6  is a sectional view showing the fixing member of the stabilizer shown in  FIG. 1 ; 
         FIG. 7  is a perspective view showing another example of the sheathing; 
         FIG. 8  is a perspective view showing another example of the sheathing; and 
         FIG. 9  is a perspective view showing another example of the fixing member. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following is a description of one embodiment of a vehicle stabilizer according to the present invention. 
       FIG. 1  shows a suspension  20  for front wheels of a vehicle provided with a stabilizer  10 . The suspension  20  (indicated by two-dot chain lines) is a double-wishbone suspension. The front wheels and the like (not shown) are mounted on left- and right-hand axle portions  21 . 
     The stabilizer  10  is composed of a stabilizer bar  12 , fixing members  14  that fix the stabilizer bar  12  to a vehicle body (not shown), stabilizer links  16  that connect end portions of the stabilizer bar  12  individually to operating parts of the suspension  20 , etc. 
     The stabilizer bar  12  is composed of a torsion part  13  spanning the width of the vehicle body and arm portions  15  individually formed on the opposite ends of the torsion part  13  and which is substantially U-shaped. When the operating parts of the suspension  20  move up and down, the arm portions  15  of the stabilizer bar  12  follow such actions, whereupon the torsion part  13  is twisted so that the suspension  20  is kept stable by its torsional reaction force. 
     The pair of fixing members  14  are provided individually on the axially opposite ends of the torsion part  13 . As shown in  FIG. 2 , each fixing member  14  is composed of a mounting fixture  22 , a rubber bush  24 , and a sheathing  26 , and is fixed to a frame part (not shown) of the vehicle body. 
     As shown in  FIG. 3 , the mounting fixture  22  is a substantially U-shaped metal plate, and lugs  27  extend individually sideways from the opposite ends of the fixture  22 . A bolt hole  28  is formed in each lug  27 . A bolt (not shown) is passed through each bolt hole  28 , whereby the mounting fixture  22  is fixed to the frame of the vehicle body. 
     The rubber bush  24  is formed of a rubber material with a predetermined hardness and has a shape suitable for the U-shape inside the mounting fixture  22 . Further, the rubber bush  24  is formed with a through-hole  30  that penetrates the substantial center of the rubber bush  24 . The through-hole  30  has an inner surface shape corresponding to the external shape of the sheathing  26 . Furthermore, the rubber bush  24  is formed with a cut portion  32  that extends from inside the through-hole  30  to the outer surface of the rubber bush  24 . The cut portion  32  in the rubber bush  24  enables the through-hole  30  to open above and below the cut portion  32 . 
     The sheathing  26  is made of a resin and composed of a collar portion  34  and a cylinder portion  36  continuous with the collar portion  34 , as shown in  FIG. 5 . The sheathing  26  is formed by, for example, injection molding and is integrally fixed to the stabilizer bar  12 . 
     The collar portion  34  is a discoid that is formed substantially at right angles to the stabilizer bar  12 , as shown in  FIG. 6 . The cylinder portion  36  is formed substantially parallel to the axis of the stabilizer bar  12  and has a rugged configuration on its outer peripheral surface. The rugged configuration is a point-symmetric shape such that its cross section perpendicular to the central axis of the stabilizer bar  12  has six uniform tops.  FIG. 6  is a sectional view of the fixing member  14  taken along a line that passes through the tops and bottoms of the rugged configuration of cylinder portion  36 . 
     Further, the sheathing  26  basically has a sufficient hardness such that it cannot be easily deformed and is fixed in close proximity to the stabilizer bar  12  without a gap. The sheathing  26  is molded after the outer surface of the stabilizer bar  12  is shot-peened and before the outer surface of the stabilizer bar  12  is coated. Fine irregularities are formed on the surface of the stabilizer bar  12  by shot peening, so that the bite of the sheathing  26  on the stabilizer bar  12  is improved by the anchor effect of the irregularities. 
     The shot peening may be that conventionally performed to improve the durability and the like of the stabilizer bar  12 . Further, any other processing means may be used for the purpose as long as the bite of the resin on the stabilizer bar  12  can be improved. Depending on the type of the resin, furthermore, the sheathing  26  may be molded on the stabilizer bar  12  with a smooth surface provided that the resin of the sheathing  26  and the stabilizer bar  12  to be combined are fully fixed. If the adhesion of the resin to the stabilizer bar  12  is unsatisfactory, in contrast with this, a molded portion of the sheathing  26  may additionally be knurled or serrated after being shot-peened. 
     Further, the rubber bush  24  has an external shape larger than the internal shape of the mounting fixture  22 , and the through-hole  30  is formed with a shape smaller than the external shape of the cylinder portion  36  of the sheathing  26 . Thus, if the mounting fixture  22  is fitted on the outside of the rubber bush  24 , which is mounted on the sheathing  26 , and fixed to the vehicle body frame, the rubber bush  24  is pressed inward by both the sheathing  26  and the mounting fixture  22 . Accordingly, the fixing member  14  that is fixed to the vehicle body frame is kept in a state such that a compressive force (preload) is continually applied to the inside of the rubber bush  24 . Preferably, the preload should be set to a sufficiently large value such that it cannot be reduced to zero when the stabilizer  10  operates. 
     The through-hole  30  may be formed with a shape equal to or larger than the external shape of the sheathing  26 . Also in this case, the through-hole  30  is formed so that the sheathing  26  is pressed inward and subjected to a compressive force by the rubber bush  24  when the rubber bush  24  is attached to the mounting fixture  22 . 
     The following is a description of functions and effects of the stabilizer  10 . 
     Since the sheathing  26  is formed on the surface of the stabilizer bar  12  by injection molding, the stabilizer bar  12  and the sheathing  26  closely contact each other, thereby preventing water or dust from infiltrating or adhering between them. Accordingly, the surface of the stabilizer bar  12  between the stabilizer bar  12  and the sheathing  26  can be prevented from rusting, so that its durability can be improved. Since the sheathing  26  and the stabilizer bar  12  cannot be dislocated from each other, moreover, no noise can be produced. 
     Since the sheathing  26  is formed on the stabilizer bar  12  by injection molding, it can be provided with ease. Further, the sheathing  26  can be securely fixed to the stabilizer bar  12  by the shot peening for the stabilizer bar  12  before molding without requiring any special processing before the injection molding. Thus, the time required for labor and processing can be shortened, so that the manufacturing cost can be reduced considerably, as compared with the case where a conventional rubber bush is adhesively bonded or vulcanization-molded. 
     The rubber bush  24  can be opened at its cut portion  32  and assembled to the sheathing  26 , so that the stabilizer bar  12  can be easily attached to the vehicle body frame. Since the rubber bush  24  and the sheathing  26  are not adhesively bonded, moreover, the rubber bush  24  can be easily removed from the sheathing  26 . Thus, the rubber bush  24  can be replaced by a simple operation, so that the replacement cost can be reduced. 
     Since the sheathing  26  is in close contact with the rubber bush  24 , the stabilizer effect can be fully exhibited. Let it be supposed that a wheel on one side drops into a depression so that one side of the suspension  20  lowers while the vehicle is running. Thereupon, an angle is formed or extended between the left- and right-hand arm portions  15 , which twists the torsion part  13  and produces a reaction force. As the arm portions  15  then rock, the sheathings  26  are also rotated around their respective axes, so that the cylinder portions  36  rotate, thereby compressing the rubber material of the rubber bushes  24  between the tops of the cylinder portions  36  in the rotating direction of the stabilizer bar  12 . Thereupon, the compressive reaction force of the rubber bushes  24  is transmitted to the arm portions  15 , whereby the responsiveness at the initial stage of rolling is improved, so that the driving stability of the vehicle is enhanced. 
     Since the faculty of the stabilizer can be partially allocated to the rubber bushes  24  with the sheathings  26  fixed to the stabilizer bar  12 , the rigidity and spring constant of the stabilizer bar  12  can be reduced. Thus, the stabilizer  10  can be reduced in weight and cost. 
     The sheathing  26  may be fixed to the stabilizer bar  12  by adhesive bonding or welding instead of injection molding. Although the sheathing  26  should preferably be formed of a resin, moreover, it may alternatively be formed of another material, e.g., hard rubber, synthetic rubber, etc. 
     The following is a description of another example of the stabilizer  10 . 
       FIG. 7  shows a sheathing  26 . In this example, the sheathing  26  has an axially rugged configuration on its outer peripheral surface. It is formed so as not to be circumferentially dislocated from a rubber bush  24  and is axially tapered on one side. Further, a rugged configuration for integral assembly is formed on the inner surface of a through-hole  30  of the rubber bush  24  so as to correspond to the rugged configuration of the sheathing  26 . 
     When the sheathing  26  formed in this manner is assembled to the rubber bush  24 , the sheathing  26  is prevented from rotating circumferentially and from moving axially in a direction in which the diameter of the sheathing  26  increases. Thus, in the stabilizer  10  in which such sheathings  26  are bilaterally molded on a stabilizer bar  12 , fixing members  14  can prevent the stabilizer bar  12  from rotating around the axis and moving axially, so that the same effect as aforementioned can be exhibited. 
     Further,  FIG. 8  shows another example. In this example, each top part of a cylinder portion  36  has a convex shape in cross-section when cut along a plane that passes through the central axis of a stabilizer bar  12 . If a sheathing  26  formed in this manner is assembled to a rubber bush  24  that has a through-hole  30  corresponding to this rugged configuration, circumferential dislocation can be restrained by the top parts. Since the top parts are convex with respect to the axial direction, moreover, an axial movement can also be restrained. In this example, each top part of the cylinder portion  36  may have a concave shape, depressed in the center, instead of being convex. 
       FIG. 9  shows an example in which the transverse width of a rubber bush  24  is longer than that of a sheathing  26  along the axis of a stabilizer bar  12 . Thus, the sheathing  26  covers the inside of the rubber bush  24  so that water, dust, etc., can be prevented from infiltrating between the rubber bush  24  and the sheathing  26 . Further, the sheathing  26  may be formed so that its axial width is longer than that of the rubber bush  24  along the stabilizer bar  12 , that is, the sheathing  26  is exposed on the opposite sides of the rubber bush  24 . 
     Although the sheathing  26  is formed axially with the stabilizer bar  12  in the example described above, they need not always be coaxial with each other. Further, the cross section of the stabilizer bar  12  may be of any desired shape other than a circular shape and may be either hollow or solid. Although the fixing member  14  is provided on the frame of the vehicle body, the distal end of the arm portion may be attached to the frame. 
     The sheathing  26  should only be formed with one irregularity provided that the rubber bush  24  and the sheathing  26  can engage each other at least circumferentially. The collar portion  34  may be formed in any desired position along the axis, e.g., in the center of the sheathing  26 , instead of being formed on the axial end portion of the sheathing  26 . 
     The outer surface of the sheathing  26  and the inner surface of the rubber bush  24  need not be in close contact with each other throughout the circumference of the sheathing  26 . Further, the sheathing  26  and the rubber bush  24  may be configured so that a gap is formed between them when the stabilizer  10  is driven to twist the stabilizer bar  12 . 
     Furthermore, the sheathing  26  may be provided with a projection member that is configured to be inserted through the inner surface of the rubber bush  24 . Specifically, the projection member may be inserted into a crack that is formed in the inner wall surface of the through-hole  30  of the rubber bush  24  by the projection member. Alternatively, a plurality of projections may be formed on the surface of the sheathing  26  and caused to engage with the inner surface of the through-hole  30  of the rubber bush  24 . 
     The rubber bush  24  may be attached to the sheathing  26  through the axial end of the stabilizer bar  12  without being formed with the cut portion  32 . 
     The mounting fixture  22  may be fitted into a hollow that is formed in the outer peripheral surface of the rubber bush  24 . If this is done, the rubber bush  24  can be prevented from being disengaged from the mounting fixture  22  even when the rubber bush  24  is subjected to a force along the axis of the stabilizer bar  12 . 
     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.