Abstract:
A head-lamp having an adjuster construction comprising a pivot portion and an adjusting screw portion, in which a ball joint is provided for at least one of said portions, a part of a carrying surface of the ball joint being formed of a soft elastic member which extends into the region of the ball joint.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to head-lamps mounted on an automobile or the like, and more specifically to a construction of an adjuster for matching an illuminating direction with a vehicle body. 
     2. Description of the Prior Art 
     FIG. 4 shows a conventional head-lamp 51 of this kind. A pivot portion 52 and an adjusting screw portion 53 are provided on the head-lamp 51 to form an adjuster construction, in which when it is mounted on an automobile (not shown), an illuminating direction can be corrected. Normally, as the pivot portion 52, a ball joint comprising a shaft surface 52a in the form of a spherical surface and a carrying surface 52 in the form of a spherical concave surface is used. The adjusting screw portion 53 is provided with an adjusting screw 53a, a screw head receiving portion 53b and a nut 53c. The adjusting screw 53a is rotated to vary a spacing between the screw receiving portion 53b and the nut 53c to correct an illuminating direction of the head lamp 51. Since the head-lamp 51 is rotated about the pivot portion 52, a ball joint having a construction similar to said pivot portion 52 is used for either said screw head receiving portion 53b or the nut 53c (an example of the screw head receiving portion 53b is shown) to cope therewith to prevent an occurrence of variation in the rotational torque when stress applied to the adjusting screw 53a is corrected. 
     However, it is general in terms of hardness or ease in molding, in the conventional ball joint the shaft surface 52a is principally formed from a metal member whereas the carrying surface 52b is formed from a resin member. Therefore, the external surface is surrounded by a member having a large coefficient of thermal expansion, and a surplus fastening force is produced due to a variation in environmental temperature, resulting in an occurrence of a rotational torque of the adjusting screw 53a. There poses a problem in that for example, in an extremely cold season, correction work becomes impossible due to the aforesaid fastening force. In an extremely hot season, the rotational torque becomes extremely small, thus posing a problem in that a retentiveness of correction is lowered. These problems have been required to be solved. 
     SUMMARY OF THE INVENTION 
     For solving the above-described problems encountered in the prior art, the present invention provides a head-lamp having an adjuster construction comprising a pivot portion and an adjusting screw portion, in which a ball joint is used for at least one side, characterized by the adjuster construction in which a part of a carrying surface of said ball joint is formed from a soft elastic member. With this arrangement, a variation of the rotational torque due to a temperature differential is prevented. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view showing one embodiment of a head-lamp according to the present invention; 
     FIG. 2 is an enlarged sectional view showing essential parts of the above embodiment; 
     FIG. 3 is likewise an enlarged sectional view of another essential parts; and 
     FIG. 4 is a sectional view of a conventional head-lamp. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In FIG. 1, a head-lamp is indicated at 1. The head-lamp 1 is provided with a pivot portion 2 and an adjusting portion 3 to form an adjuster construction, in which an illuminating direction can be corrected. The pivot portion 2 comprises a ball joint composed of a shaft surface 2a  in the form of a spherical convex surface and a carrying surface 2b in the form of a spherical concave surface. On the other hand, the adjusting screw portion 3 is composed of an adjusting screw 31, a screw head receiving portion 32 and a nut 33. Similar to prior art, a head of the adjusting screw 31 is machined into a spherical surface to form a shaft surface 31a, and the screw head receiving portion 32 is formed with a carrying surface 32a to form a ball joint. According to the present invention the carrying surfaces 2b and 32b are partly formed from soft elastic members 4 and 5, for example, such as rubber. 
     FIG. 2 shows in an enlarged scale the pivot portion 2 which constitutes an essential part. Since the carrying surface 2b is in the form of a spherical concave surface as described above, it cannot be molded in that state. Therefore, it is divided into two hemispherical concave surfaces, which are joined after the shaft surface 2a has been fitted. In this embodiment, the aforesaid division is carried out parallel with an axial direction 2 of the shaft surface 2a. 
     In this case, one hemispherical concave surfaces formed by dividing the carrying surface 2b is provided with a hole with a bottom 2c which is approximately at a right angle to the carrying surface. A rod-like elastic member 4 which is slightly longer than the depth of the hole with bottom 2c is inserted into the hole with bottom 2c. 
     FIG. 3 shows essential parts of the adjusting screw 3. In this example, a carrying surface 32a is divided approximately at right angles to the axial direction X of the shaft surface 31a. 
     In this case, one of the carrying surfaces 32a is provided with a circular groove 32b, into which is fitted an elastic member 5 commercially available as an O-ring, for example, so that the elastic member 5 is projected slightly in a direction of the shaft surface 31a. 
     In any of these examples as described above, the carrying surfaces 2b and 32a are formed in a proper fitting state with respect to the shaft surfaces 2a and 31a at a minimum temperature at which use of the head-lamp is expected. 
     The operation and effect of the present invention are as follows. The carrying surfaces 2b and 32a sides increase in size as a temperature during use rises to naturally produce a play in the shaft surfaces 2a and 31a. 
     Since the elastic members 4 and 5 are projected beyond the concave surfaces 26, 32a, the elastic members 4 and 5 are still in contact with the shaft surfaces 2a and 31a to absorb the play, and at the same time, torque for rotating the shaft surfaces 2a and 31a with the elasticity is prevented from being greatly varied. 
     As described above, according to the present invention, a head-lamp has an adjuster construction in which a part of a carrying surface of a ball joint is formed from a soft elastic member. Therefore, the present invention has an excellent advantage in that rotational torque of the adjusting screw portion caused by a variation in temperature is prevented from being greatly varied due to the elasticity of the elastic member and an occurrence of surplus fastening or play is prevented whereby correction can be made under any temperature conditions.