Abstract:
A tractor headlight device according to the present invention is configured from a pair of high-beam units and a pair of low-beam units, wherein the high-beam units and the low-beam units are respectively disposed at top and bottom. High-beam lamp lenses configuring the high-beam units are formed extending from the front to the sides of a hood. Low-beam lamp lenses configuring the low-beam units are formed along a front grill under the high-beam units.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a headlight device of a tractor. 
       BACKGROUND ART 
       [0002]    Conventionally, a tractor used in farmland is known (for example, see the Patent Literature 1). In a front part of the tractor, a bonnet is provided, and an engine is housed in the bonnet. In a front surface of the bonnet, a headlight device is arranged. 
         [0003]    The tractor has a characteristic that the bonnet is long and slender and a front surface area of the bonnet is small. In the tractor, a large front grill is provided in a front surface of the bonnet so as to take air in an inside of the bonnet. Accordingly, the headlight device of the tractor must be made small and cannot make a strong impression on a third person even when the headlight device is turned on. As a result, there is a problem that visibility by the third person is low. Accordingly, an art which can make a strong impression on a third person so as to improve visibility is desired. 
       PRIOR ART REFERENCE 
     Patent Literature 
       [0000]    
       
         Patent Literature 1: the Japanese Patent Laid Open Gazette 2010-163036 
       
     
       DISCLOSURE OF INVENTION 
     Problems to be Solved by the Invention 
       [0005]    The purpose of the present invention is to provide an art which can make a strong impression on a third person so as to improve visibility. 
       Means for Solving the Problems 
       [0006]    The first mode of the present invention is a headlight device of a tractor including a pair of high-beam units, and a pair of low-beam units, wherein the high-beam units and the low-beam units are arranged respectively at upper and lower sides. 
         [0007]    The second mode of the present invention is the headlight device according to the first mode wherein the high-beam unit includes a high-beam lamp, a high-beam lamp housing supporting the high-beam lamp, and a high-beam lamp lens covering the high-beam lamp, and the high-beam lamp lens is formed from a front surface to a side surface of a bonnet. 
         [0008]    The third mode of the present invention is the headlight device according to the second mode wherein the high-beam lamp lens is formed so as to be projected from the side surface of the bonnet. 
         [0009]    The fourth mode of the present invention is the headlight device according to the third mode wherein the high-beam unit includes a reflector reflecting light of the high-beam lamp, and an inner casing covering the reflector, and the inner casing is projected from the side surface of the bonnet and formed along an inner surface of the high-beam lamp lens. 
         [0010]    The fifth mode of the present invention is the headlight device according to the fourth mode wherein glossy plating is applied to an outer surface of the inner casing opposite to the high-beam lamp lens. 
         [0011]    The sixth mode of the present invention is the headlight device according to the first mode wherein the low-beam unit includes a low-beam lamp, a low-beam lamp housing supporting the low-beam lamp, and a low-beam lamp lens covering the low-beam lamp, and the low-beam lamp lens is formed along a front grill below the high-beam unit. 
         [0012]    The seventh mode of the present invention is the headlight device according to the sixth mode wherein the low-beam unit has one or more illumination lamps, and the illumination lamp highlights a zone along an outline of the low-beam lamp lens. 
         [0013]    The eighth mode of the present invention is the headlight device according to the seventh mode wherein the illumination lamps are turned on following turning on of a work lamp and turned off following turning off of the work lamp. 
         [0014]    The ninth mode of the present invention is the headlight device according to one of first to eighth modes wherein the high-beam unit and the low-beam unit are connected to each other via a bracket. 
         [0015]    The tenth mode of the present invention is a tractor including the headlight device according to one of first to ninth modes. 
         [0016]    The eleventh mode of the present invention is a tractor including the headlight device according to one of first to ninth modes, and a symbol mark arranged at a center of the headlight device. 
       Effect of the Invention 
       [0017]    The present invention brings the following effects. 
         [0018]    According to the first mode of the present invention, the headlight device of the tractor according to the application includes the pair of the high-beam units, and the pair of the low-beam units, wherein the high-beam units and the low-beam units are arranged respectively at the upper and lower sides. 
         [0019]    Accordingly, in the tractor having the headlight device, an illumination part in the front surface of the bonnet (a part which can emit light) has upper and lower two stages. Accordingly, the tractor can make a strong impression on a third person so as to improve visibility. 
         [0020]    According to the second mode of the present invention, the high-beam unit includes the high-beam lamp, the high-beam lamp housing supporting the high-beam lamp, and the high-beam lamp lens covering the high-beam lamp. The high-beam lamp lens is formed from the front surface to the side surface of the bonnet. Accordingly, in the tractor having the headlight device, an illumination part which is extended laterally can be secured from the front surface to the side surface of the bonnet. Therefore, the tractor can make a strong impression on a third person so as to improve visibility. 
         [0021]    According to the third mode of the present invention, the high-beam lamp lens is formed so as to be projected from the side surface of the bonnet. Accordingly, the tractor having the headlight device can illuminate by light emitted from an upper surface and a lower surface of the high-beam lamp lens. Therefore, the tractor can make a strong impression on a third person so as to improve visibility. 
         [0022]    According to the fourth mode of the present invention, the high-beam unit includes the reflector reflecting light of the high-beam lamp, and the inner casing covering the reflector. The inner casing is projected from the side surface of the bonnet and formed along the inner surface of the high-beam lamp lens. Accordingly, in the tractor having the headlight device, the high-beam lamp lens constituting the side surface of the bonnet can be made bright substantially uniformly. Therefore, the tractor can make a strong impression on a third person so as to improve visibility. 
         [0023]    According to the fifth mode of the present invention, glossy plating is applied to the outer surface of the inner casing opposite to the high-beam lamp lens. Accordingly, in the tractor having the headlight device, the high-beam lamp lens constituting the side surface of the bonnet can be made bright substantially uniformly further. Therefore, the tractor can make a strong impression on a third person so as to improve visibility. 
         [0024]    According to the sixth mode of the present invention, the low-beam unit includes the low-beam lamp, the low-beam lamp housing supporting the low-beam lamp, and the low-beam lamp lens covering the low-beam lamp. The low-beam lamp lens is formed along the front grill below the high-beam unit. Accordingly, in the tractor having the headlight device, an illumination part (a part which can emit light) which is extended longitudinally can be secured below the high-beam unit. Therefore, the tractor can make a strong impression on a third person so as to improve visibility. 
         [0025]    According to the seventh mode of the present invention, the low-beam unit has one or more illumination lamps. The illumination lamp highlights the zone along the outline of the low-beam lamp lens. Accordingly, in the tractor having the headlight device, the outline of the low-beam lamp lens extended longitudinally can be emphasized. Therefore, the tractor can make a strong impression on a third person so as to improve visibility. 
         [0026]    According to the eighth mode of the present invention, the illumination lamps are turned on following turning on of the work lamp and turned off following turning off of the work lamp. Accordingly, in the tractor having the headlight device, appearance of the low-beam lamp lens is changed corresponding to a driving state. Therefore, the tractor can make a strong impression on a third person so as to improve visibility. 
         [0027]    According to the ninth mode of the present invention, the high-beam unit and the low-beam unit are connected to each other via a bracket. Accordingly, in the tractor having the headlight device, the one high-beam unit and the one low-beam unit is configured integrally. Therefore, assembly processes of the tractor can be simplified so as to improve production efficiency. 
         [0028]    According to the tenth mode of the present invention, the tractor has the headlight device according to one of first to ninth modes. Accordingly, the tractor can make a strong impression on a third person so as to improve visibility. 
         [0029]    According to the eleventh mode of the present invention, the tractor has the headlight device according to one of first to ninth modes, and the symbol mark arranged at the center of the headlight device. Accordingly, the tractor can make a strong impression on a third person so as to improve visibility. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0030]      FIG. 1  is a drawing of a tractor. 
           [0031]      FIG. 2  is a drawing from a direction of an arrow X in  FIG. 1 . 
           [0032]      FIG. 3  is a drawing from a direction of an arrow Y in  FIG. 1 . 
           [0033]      FIG. 4  is a drawing from a direction of an arrow Z in  FIG. 1 . 
           [0034]      FIG. 5  is a drawing of a bonnet. 
           [0035]      FIG. 6  is a drawing from a direction of an arrow X in  FIG. 5 . 
           [0036]      FIG. 7  is a drawing from a direction of an arrow Y in  FIG. 5 . 
           [0037]      FIG. 8  is a drawing from a direction of an arrow Z in  FIG. 5 . 
           [0038]      FIG. 9  is a drawing of a headlight device. 
           [0039]      FIG. 10  is a drawing of a structure of the high-beam unit. 
           [0040]      FIG. 11  is a drawing of a section of the high-beam unit. 
           [0041]      FIG. 12  is a drawing of a state in which the high-beam unit illuminates the front. 
           [0042]      FIG. 13  is a drawing of a structure of the low-beam unit. 
           [0043]      FIG. 14  is a drawing of a section of the low-beam unit. 
           [0044]      FIG. 15  is a drawing of a state in which the low-beam unit illuminates the front. 
           [0045]      FIG. 16  is a drawing of a state in which an illumination lamp is turned on. 
           [0046]      FIG. 17  is a drawing of a state in which the high-beam unit is connected to the low-beam unit. 
           [0047]      FIG. 18  is a drawing of a headlight device according to a second embodiment. 
           [0048]      FIG. 19  is a drawing of a headlight device according to a third embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0049]    Technical thought of the present invention can be used for all agricultural machine vehicles and construction machine vehicles. 
         [0050]    Firstly, a tractor  1  is explained. 
         [0051]      FIG. 1  shows the tractor  1 .  FIG. 2  is a drawing from a direction of an arrow X in  FIG. 1 , and  FIG. 3  is a drawing from a direction of an arrow Y in  FIG. 1 . Furthermore,  FIG. 4  is a drawing from a direction of an arrow Z in  FIG. 1 . In the drawings, longitudinal, lateral and vertical directions of the tractor  1  are shown. 
         [0052]    The tractor  1  includes mainly a chassis frame  11 , an engine  12 , a transmission  13 , a front axle  14  and a rear axle  15 . In the tractor  1 , in addition to a cabin  16  which protects an operator from a rainstorm, a bonnet  2  which protects the engine  12  from a rainstorm is provided. 
         [0053]    The chassis frame  11  constitutes a frame of the tractor  1 . The engine  12  and the like explained below are attached to the chassis frame  11 . 
         [0054]    The engine  12  exchanges heat energy obtained by combustion of fuel into kinetic energy. Namely, the engine  12  generates rotation power by making the fuel burn. When an operator operates an accelerator pedal, driving state of the engine  12  is changed corresponding to the operation. 
         [0055]    The transmission  13  transmits the rotation power of the engine  12  to the front axle  14  and the rear axle  15 . The rotation power of the engine  12  is inputted to the transmission  13  via a connection mechanism. The transmission  13  has a hydraulic-mechanical type stepless transmission (HMT or iHMT). When an operator operates a shift lever, operation state of the stepless transmission is changed corresponding to the operation. 
         [0056]    The front axle  14  transmits the rotation power of the engine  12  to front wheels  141 . The rotation power of the engine  12  is inputted to the front axle  14  via the transmission  13 . The front axle  14  is juxtaposed with a steering device. When an operator operates a steering wheel, the steering device changes a steering angle of the front wheels  141  corresponding to the operation. 
         [0057]    The rear axle  15  transmits the rotation power of the engine  12  to rear wheels  151 . The rotation power of the engine  12  is inputted to the rear axle  15  via the transmission  13 . A PTO output device is provided in the rear axle  15 . The PTO output device inputs the rotation power to a led work machine. 
         [0058]    Next, the bonnet  2  is explained. 
         [0059]      FIG. 5  shows the bonnet  2 .  FIG. 6  is a drawing from a direction of an arrow X in  FIG. 5 , and  FIG. 7  is a drawing from a direction of an arrow Y in  FIG. 5 . Furthermore,  FIG. 8  is a drawing from a direction of an arrow Z in  FIG. 5 . In the drawings, the longitudinal, lateral and vertical directions of the tractor  1  are shown. 
         [0060]    The bonnet  2  includes mainly an upper cover  21 , a lower cover  22  and a front grill  23 . A headlight device  3  illuminating the front at night is provided in the bonnet  2 . 
         [0061]    The upper cover  21  is an exterior member covering an upper part of the engine  12 . The upper cover  21  rises up from a front end point Ua thereof and is bent downward from a middle point Ub. Behind a vent hole  21   h , the upper cover  21  curves gradually to a rear end point Uc. Furthermore, the upper cover  21  expands sideward from the front end point Ua and curves gradually so that side end points Uw are maximum width points. In the upper cover  21 , a character line C 1  is formed from the front end point Ua to the middle point Ub, and character lines C 2  are formed from the middle point Ub so as to expand sideward. The vent hole  21   h  is formed substantially wedge-like between the two character lines C 2 . 
         [0062]    The lower cover  22  is an exterior member covering a side part of the engine  12 . The lower cover  22  expands sideward from a front end point La thereof and curves gradually so that side end points Lw are maximum width points. Furthermore, whereas an upper half part of the lower cover  22  is based on a curved surface expanded outward, a lower half part of the lower cover  22  is based on a curved surface depressed inward. In the lower cover  22 , character lines C 3  which pass from the front end point La through the side end points Lw are formed. Vent holes  22   ha  are formed substantially lozenge-like above the character lines C 3 , and vent holes  22   hb  are formed substantially lozenge-like below the character lines C 3 . An upper front part of the lower cover  22  is formed corresponding to a shape of a high-beam lamp lens  43  discussed later. Since the shape of the high-beam lamp lens  43  hangs aslant, the shape of the upper front part of the lower cover  22  also hangs aslant. 
         [0063]    The front grill  23  is an exterior member covering a front part of the engine  12 . The front grill  23  has a structure in which a metal mesh  232  is stuck on a support column  231 . The support column  231  has beam parts  231 L and  231 R extended upward aslant from a center point Fa thereof and a pillar part  231 P extended downward from the center point Fa. The beam parts  231 L and  231 R and the pillar part  231 P become thin gradually as they separate from the center point Fa, and are connected to a grill frame  231 G. The metal mesh  232  covers three parts which includes a range surrounded by the beam parts  231 L and  231 R and the grill frame  231 G, a range surrounded by the beam part  231 L, the pillar part  231 P and the grill frame  231 G, and a range surrounded by the beam part  231 R, the pillar part  231 P and the grill frame  231 G. In addition, both sides of an upper part of the front grill  23  are formed corresponding to the shape of the high-beam lamp lens  43  discussed later. Since the shape of the high-beam lamp lens  43  hangs aslant, the shapes of the sides of an upper part of the front grill  23  also hang aslant. 
         [0064]    Furthermore, the bonnet  2  has below features. A center mark  21 M which is substantially I-like shaped is attached to an upper part of the upper cover  21  so as to cross the vent hole  21   h . The center mark  21 M is a sighting device for an operator to determine a traveling direction. A symbol mark  23 M which is substantially Y-like shaped is attached to a front surface of the support column  231  so as to cover the beam parts  231 L and  231 R and the pillar part  231 P. The symbol mark  23 M is a design which symbolizes a supplier maker. Glossy plating is applied to the center mark  21 M and the symbol mark  23 M so as to make a strong impression on a third person. 
         [0065]    Next, the headlight device  3  is explained in detail. 
         [0066]      FIG. 9  is shows the headlight device  3 . In the drawing, the longitudinal, lateral and vertical directions of the tractor  1  are shown. 
         [0067]    The headlight device  3  includes mainly a pair of high-beam units  4 L and  4 R and a pair of low-beam units  5 L and  5 R. The high-beam units  4 L and  4 R and the low-beam units  5 L and  5 R are arranged respectively at upper and lower sides. 
         [0068]    According to the configuration, in the tractor  1  having the headlight device  3 , an illumination part in a front surface of the bonnet  2  (a part which can emit light: see  FIGS. 12  and  15 ) has upper and lower two stages. Accordingly, the tractor  1  can make a strong impression on a third person so as to improve visibility. 
         [0069]    When the high-beam unit  4 L and the low-beam unit  5 L are fixed to predetermined positions of the bonnet  2 , they constitute a design having one light unit. Namely, the high-beam unit  4 L and the low-beam unit  5 L are combined so as to constitute the design in which they are connected integrally. 
         [0070]    Similarly, when the high-beam unit  4 R and the low-beam unit  5 R are fixed to predetermined positions of the bonnet  2 , they constitute a design having one light unit. Namely, the high-beam unit  4 R and the low-beam unit  5 R are combined so as to constitute the design in which they are connected integrally. 
         [0071]    Next, the high-beam units  4 L and  4 R are explained in detail. Below explanation pays attention to the left high-beam unit  4 L. For simplification, it is referred to as “high-beam unit  4 ”. 
         [0072]      FIG. 10  shows a structure of the high-beam unit  4 .  FIG. 11  shows a section of the high-beam unit  4 .  FIG. 12  shows a state in which the high-beam unit  4  illuminates the front. 
         [0073]    The high-beam unit  4  includes mainly a high-beam lamp  41 , a high-beam lamp housing  42  and a high-beam lamp lens  43 . 
         [0074]    The high-beam lamp  41  is a so-called halogen lamp. The halogen lamp emits light by using a halogen cycle. The halogen lamp has features of being bright and excelling in durability. 
         [0075]    The high-beam lamp housing  42  supports the high-beam lamp  41 . Concretely, a stand  42 S provided in a center part of the high-beam lamp housing  42  supports the high-beam lamp  41 . In an outer edge part  42 E of the high-beam lamp housing  42 , a plurality of slits  42   s  are formed. On the slits  42   s , lock pins  43 R of the high-beam lamp lens  43  are hooked. In the outer edge part  42 E of the high-beam lamp housing  42 , brackets  421  and  422  are provided. The high-beam lamp housing  42  is fixed via the bracket  421  to the beam part  231 L of the support column  231 . The high-beam lamp housing  42  is fixed via the bracket  422  to the grill frame  231 G of the support column  231 . 
         [0076]    The high-beam lamp lens  43  covers the high-beam lamp  41 . Concretely, the high-beam lamp lens  43  is combined with the high-beam lamp housing  42  while the high-beam lamp  41  is housed in the high-beam lamp lens  43  so as to cover the high-beam lamp  41 . In an outer edge part  43 E of the high-beam lamp lens  43 , the plurality of the lock pins  43 R are formed. The lock pins  43 R are hooked on the slits  42   s  of the high-beam lamp housing  42 . In the outer edge part  43 E of the high-beam lamp lens  43 , a projecting plate  43 P is provided. The high-beam lamp lens  43  is fixed while the projecting plate  43 P is inserted into a recessed groove  42   c  of the high-beam lamp housing  42 . Accordingly, dust and water are prevented from entering the inside. 
         [0077]    Characteristics of the high-beam unit  4  are explained below. 
         [0078]    The high-beam lamp lens  43  is formed from the front surface to a side surface of the bonnet  2  (see arrows A and B of  FIG. 9 ). Namely, the high-beam lamp lens  43  configures not only the front surface of the bonnet  2  but also the side surface of the bonnet  2  (see  FIGS. 5, 6 and 7 ). 
         [0079]    Accordingly, in the tractor  1  having the headlight device  3 , an illumination part (a part which can emit light: see  FIG. 12 ) which is extended laterally can be secured from the front surface to the side surface of the bonnet  2 . Therefore, the tractor can make a strong impression on a third person so as to improve visibility. 
         [0080]    Furthermore, the high-beam lamp lens  43  is formed so as to be projected from the side surface of the bonnet  2  (see an arrow C of  FIG. 9 ). Namely, the high-beam lamp lens  43  is not formed along the lower cover  22  but projected outward from the lower cover  22  (see  FIGS. 5, 6 and 8 ). 
         [0081]    Accordingly, the tractor  1  having the headlight device  3  can illuminate by light emitted from an upper surface  43 Us and a lower surface  43 Ds of the high-beam lamp lens  43  (see parts signed by  in  FIG. 12 ). Therefore, the tractor  1  can make a strong impression on a third person so as to improve visibility. 
         [0082]    Additionally, the high-beam unit  4  has a reflector  44  and an inner casing  45 . 
         [0083]    The reflector  44  reflects light of the high-beam lamp  41 . Concretely, the reflector  44  surrounds the high-beam lamp  41  from a center to an outer edge part  44 E thereof so as to reflect the light of the high-beam lamp  41 . In a rear surface of the reflector  44 , brackets  441  and  442  are provided. The reflector  44  is fixed via the brackets  441  and  442  to the stand  42 S of the high-beam lamp housing  42 . Glossy plating is applied to a front surface  44 Fs of the reflector  44 . Accordingly, reflectance of the light is improved. 
         [0084]    The inner casing  45  covers the reflector  44 . Concretely, the inner casing  45  is combined with the high-beam lamp housing  42  while the reflector  44  is housed in the inner casing  45  so as to cover the reflector  44 . In a predetermined position of the inner casing  45 , a substantially lozenge-like opening  45   h  is provided. The inner casing  45  is fixed so that the opening  45   h  is arranged inside the outer edge part  44 E of the reflector  44 . Glossy plating is applied to an outer surface  450   s  of the inner casing  45 . Accordingly, reflectance of the light is improved. 
         [0085]    Other characteristics of the high-beam unit  4  are explained below. 
         [0086]    The inner casing  45  is projected from the side surface of the bonnet  2  and formed along an inner surface  431   s  of the high-beam lamp lens  43  (see the arrow C of  FIG. 9 ). Namely, the inner casing  45  is projected outward from the lower cover  22  and is separated from the inner surface  431   s  of the high-beam lamp lens  43  for a fixed interval. Accordingly, the light of the high-beam lamp  41  passes between the outer surface  450   s  of the inner casing  45  and the inner surface  431   s  of the high-beam lamp lens  43  and reaches an end of the high-beam lamp lens  43  (see an arrow L of  FIG. 11 ). 
         [0087]    Accordingly, in the tractor  1  having the headlight device  3 , the high-beam lamp lens  43  constituting the side surface of the bonnet  2  can be made bright substantially uniformly (see  FIG. 12 ). Therefore, the tractor  1  can make a strong impression on a third person so as to improve visibility. 
         [0088]    Furthermore, as mentioned above, in the inner casing  45 , glossy plating is applied to the outer surface  450   s  opposite to the high-beam lamp lens  43 . Concretely, chromium plating is applied. Accordingly, the light of the high-beam lamp  41  is hard to decline even when reflected by the outer surface  450   s  of the inner casing  45  and reaches the end of the high-beam lamp lens  43  certainly. Accordingly, the whole high-beam lamp lens  43  is made bright. 
         [0089]    Accordingly, in the tractor  1  having the headlight device  3 , the high-beam lamp lens  43  constituting the side surface of the bonnet  2  can be made bright substantially uniformly further (see  FIG. 12 ). Therefore, the tractor  1  can make a strong impression on a third person so as to improve visibility. 
         [0090]    Next, the low-beam units  5 L and  5 R are explained in detail. Below explanation pays attention to the left low-beam unit  5 L. For simplification, it is referred to as “low-beam unit  5 ”. 
         [0091]      FIG. 13  shows a structure of the low-beam unit  5 .  FIG. 14  shows a section of the low-beam unit  5 .  FIG. 15  shows a state in which the low-beam unit  5  illuminates the front. 
         [0092]    The low-beam unit  5  includes mainly a low-beam lamp  51 , a low-beam lamp housing  52  and a low-beam lamp lens  53 . 
         [0093]    The low-beam lamp  51  is a so-called halogen lamp. The halogen lamp emits light by using a halogen cycle. The halogen lamp has features of being bright and excelling in durability. The low-beam lamp  51  is housed in a projector unit  511 . The projector unit  511  includes a reflector  512  and a lens  513 . The lens  513  converges light of the low-beam lamp  51  so that the light with high directivity is emitted (the light hard to be diffused is emitted) from the lens  513 . However, the lens  513  may be omitted. 
         [0094]    The low-beam lamp housing  52  supports the low-beam lamp  51 . Concretely, the projector unit  511  is fixed to a center part of the low-beam lamp housing  52  so as to support the low-beam lamp  51 . In an outer edge part  52 E of the low-beam lamp housing  52 , a plurality of slits  52   s  are formed. On the slits  52   s , lock pins  53 R of the low-beam lamp lens  53  are hooked. In the outer edge part  52 E of the low-beam lamp housing  52 , brackets  521  and  522  are provided. The low-beam lamp housing  52  is fixed via the bracket  521  to the grill frame  231 G of the support column  231 . The low-beam lamp housing  52  is fixed via the bracket  522  to the lower cover  22 . 
         [0095]    The low-beam lamp lens  53  covers the low-beam lamp  51 . Concretely, the low-beam lamp lens  53  is combined with the low-beam lamp housing  52  while the projector unit  511  is housed in the low-beam lamp housing  52  so as to cover the low-beam lamp  51 . In an outer edge part  53 E of the low-beam lamp lens  53 , the plurality of the lock pins  53 R are formed. The lock pins  53 R are hooked on the slits  52   s  of the low-beam lamp housing  52 . In the outer edge part  53 E of the low-beam lamp lens  53 , a projecting plate  53 P is provided. The low-beam lamp lens  53  is fixed while the projecting plate  53 P is inserted into a recessed groove  52   c  of the low-beam lamp housing  52 . Accordingly, dust and water are prevented from entering the inside. 
         [0096]    Characteristics of the low-beam unit  5  are explained below. 
         [0097]    The low-beam lamp lens  53  is formed along the front grill  23  below the high-beam unit  4  (see an arrow D of  FIG. 9 ). Namely, the low-beam lamp lens  53  is arranged below the high-beam lamp lens  43  while being engaged with the front grill  23  (see  FIGS. 5 and 6 ). 
         [0098]    Accordingly, in the tractor  1  having the headlight device  3 , an illumination part (a part which can emit light: see  FIG. 15 ) which is extended longitudinally can be secured below the high-beam unit  4 . Therefore, the tractor  1  can make a strong impression on a third person so as to improve visibility. 
         [0099]    Additionally, the low-beam unit  5  has an inner plate  54  and an illumination lamp  55 . 
         [0100]    The inner plate  54  covers the projector unit  511 . Concretely, the inner plate  54  is combined with the low-beam lamp housing  52  while the projector unit  511  is housed in the low-beam lamp housing  52  so as to cover the projector unit  511 . In a predetermined position of the inner plate  54 , a circular opening  54   h  is provided. The inner plate  54  is fixed by engaging the lens  513  of the projector unit  511  with the opening  54   h . Glossy plating is applied to a front surface  54 Fs of the inner plate  54 . Accordingly, reflectance of the light is improved. 
         [0101]    The illumination lamp  55  is a so-called LED light emitting diode. The LED light emitting diode emits light using an electroluminescence effect. The LED light emitting diode has features of being bright and excelling in durability. In the low-beam unit  5 , total 18 illumination lamps  55  are arranged along an outline of an inner end side of the low-beam lamp lens  53 . The illumination lamps  55  are housed in a highlight unit  551 . The highlight unit  551  includes a mount  552  and a cover  553 . Since the cover  553  irregularly reflects light of the LED light emitting diodes, it seems that the cover  553  emits light uniformly (it seems that surface light emission is performed). However, the cover  553  may be omitted. 
         [0102]    Other characteristics of the low-beam unit  5  are explained below. 
         [0103]    The illumination lamp  55  highlights a zone along an outline of the low-beam lamp lens  53 . Namely, the illumination lamp  55  illuminates a fixed range along the outline of the low-beam lamp lens  53  line-like. “Illuminates line-like” includes the case in which a curved surface of light is drawn by the surface light emission of the cover  553  and the case in which a curved surface of light is drawn by light emission of the illumination lamps  55  arranged continuously. 
         [0104]    Accordingly, in the tractor  1  having the headlight device  3 , the outline of the low-beam lamp lens  53  extended longitudinally can be emphasized (see  FIG. 16 ). Therefore, the tractor  1  can make a strong impression on a third person so as to improve visibility. 
         [0105]    Furthermore, the illumination lamps  55  are turned on following turning on of a work lamp  161  and turned off following turning off of the work lamp  161 . Herein, the work lamp  161  illuminates the front side and surrounding thereof of the bonnet  2  at the time of working. In the tractor  1 , the work lamp  161  is arranged in the cabin  16  (see  FIGS. 1, 2 and 3 ). 
         [0106]    Accordingly, in the tractor  1  having the headlight device  3 , appearance of the low-beam lamp lens  53  is changed corresponding to a driving state. Therefore, the tractor  1  can make a strong impression on a third person so as to improve visibility. 
         [0107]    The above is the explanation of the high-beam unit  4  and the low-beam unit  5  constituting the headlight device  3 . The high-beam unit  4  and the low-beam unit  5  are connected to each other via a bracket  6  (see  FIG. 17 ). 
         [0108]    Accordingly, in the tractor  1  having the headlight device  3 , the one high-beam unit  4  and the one low-beam unit  5  is configured integrally. Therefore, assembly processes of the tractor  1  can be simplified so as to improve production efficiency. 
         [0109]    In the headlight device  3 , the bracket  6  includes a first bracket  6   a  and a second bracket  6   b . The first bracket  6   a  is projected upward from the low-beam lamp housing  52  and connected to the high-beam unit  4 . The second bracket  6   b  is projected from the low-beam lamp housing  52  toward an inner end and connected to the high-beam unit  4 . The first bracket  6   a  and the second bracket  6   b  are separated suitably so as to suppress shakiness. 
         [0110]    Next, headlight devices  3 S and  3 T according to other embodiments are explained. 
         [0111]      FIG. 18  shows the headlight device  3 S according to a second embodiment.  FIG. 19  shows the headlight device  3 T according to a third embodiment. In each of the drawings, the headlight device  3  according to the first embodiment is shown for comparison. 
         [0112]    In the low-beam unit  5  of the headlight device  3 S, the plurality of the illumination lamps  55  are arranged along the outline at the sides of inner and lower ends of the low-beam lamp lens  53 . Accordingly, the illumination lamps  55  highlight a zone along the outline at the sides of inner and lower ends of the low-beam lamp lens  53 . Namely, the illumination lamp  55  illuminates a fixed range along the outline at the sides of inner and lower ends of the low-beam lamp lens  53  line-like. 
         [0113]    Accordingly, in the tractor  1  having the headlight device  3 S, the outline of the low-beam lamp lens  53  extended longitudinally can be emphasized. The design which emphasized the acute angle is obtained so as to bring a sharp impression. Therefore, the tractor  1  can make a strong impression on a third person so as to improve visibility. 
         [0114]    In the low-beam unit  5  of the headlight device  3 T, the plurality of the illumination lamps  55  are arranged so as to occupy an upper half of the low-beam lamp lens  53 . Accordingly, the illumination lamps  55  highlight the upper half of the low-beam lamp lens  53 . Namely, the illumination lamp  55  illuminates a range occupying the upper half of the low-beam lamp lens  53 . 
         [0115]    Accordingly, in the tractor  1  having the headlight device  3 T, the outline of the low-beam lamp lens  53  extended longitudinally can be emphasized. The design which emphasized width of the illumination part is obtained so as to bring a gorgeous impression. Therefore, the tractor  1  can make a strong impression on a third person so as to improve visibility. 
       INDUSTRIAL APPLICABILITY 
       [0116]    The present invention can be used for an art of a headlight device of a tractor. 
       DESCRIPTION OF NOTATIONS 
       [0000]    
       
         
           
               1  tractor 
               6  bracket 
               11  chassis frame 
               12  engine 
               13  transmission 
               14  front axle 
               15  rear axle 
               16  cabin 
               2  bonnet 
               21  upper cover 
               22  lower cover 
               23  front grill 
               3  headlight device 
               4  high-beam unit 
               41  high-beam lamp 
               42  high-beam lamp housing 
               43  high-beam lamp lens 
               44  reflector 
               45  inner casing 
               5  low-beam unit 
               51  low-beam lamp 
               52  low-beam lamp housing 
               53  low-beam lamp lens 
               54  inner plate 
               55  illumination lamp