| Title of Invention | VEHICLE LAMP WITH TRANSPARENT RESIN COVER |
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| Abstract | A vehicle lamp includes: a lamp body that is formed in a shape to have a front opening portion being opened forward; a transparent resin cover that is attached to the lamp body to cover the front opening portion and to form a lamp room between the transparent resin cover and the lamp body; and a light source that is disposed inside the lamp room, wherein the transparent resin cover is formed to have a flange portion for a gate, the flange portion having a linear fan gate trace on a leading edge thereof and being formed to protrude outward from an outer peripheral edge portion of the transparent resin cover. |
| Full Text | VEHICLE LAMP CROSS REFERENCE TO RELATED APPLICATION(S) The present disclosure relates to the subject matters contained in Japanese Patent Application No. 2008-332510 filed on December 26, 2008, which are incorporated herein by reference in its entirety. FIELD The present invention relates to a vehicle lamp having a light source in a lamp room formed by a lamp body being opened forward and a transparent resin cover attached to the lamp body at the opening. BACKGROUND In recent years, vehicle lamps which are to be provided on vehicles are tend to have a larger size of a front opening portion of a lamp body and to have a complex three-dimensional shape in which a resin cover is provided to cover a wide three-dimensional area from a front to a side of the vehicle. On the other hand, the vehicle lamp is generally required to be lighter in weight in order to reduce a power for driving the vehicle and is desired to reduce a thickness of the resin cover that has a high weight component percentage. Generally, the resin cover is monolithically molded by a polycarbonate (PC) resin which has great impact strength and is also excellent in a heat resistance. However, the polycarbonate resin has a low fluidity. When injection molding is to be performed with a cavity of a metal mold having a standard side gate, a pressure loss of an injection pressure at the side gate is increased. Therefore, the metal mold having the standard side gate cannot cope with a large-sized thin resin cover. In view of this, there is proposed a method of injection molding a comparatively large-sized thin component by employing a fan gate formed in fan-shape toward a cavity of a metal mold. An example of such fan gate is disclosed in JP-A-11-077758. The fan gate is a gate having a large width and a large sectional area. For this reason, a cut remainder, a burr or a bite is caused so that quality of a gate processing surface is apt to be deteriorated. Particularly in a case in which a gate position is provided on a curved part of the cavity, it becomes difficult to cut the gate by a cutter and it also becomes difficult to ensure repeating precision in a cutting trace by a cutting work performed by use of a laser beam. Accordingly, by positioning the gate on a straight part of the cavity, cutting precision can be enhanced because the gate processing surface becomes straight shape. However, many resin covers of recent vehicle lamps take a complex three-dimensional shape being formed by combining a plurality of curved portions and fewer amounts of portions having simple rectangular shape. When the gate is positioned on the straight part of the cavity, a, flow length of a molten resin is increased so that a pressure loss of an injection pressure is increased. For this reason, there is a difficulty in that an advantage for reducing a thickness through an employment of a fan gate is lessened. SUMMARY One of objects of the present invention is to provide a vehicle lamp provided with a resin cover having a complex three-dimensional shape and having a small thickness and weight. According to an aspect of the invention, there is provided a vehicle lamp including: a lamp body that is formed in a shape to have a front opening portion being opened forward; a transparent resin cover that is attached to the lamp body to cover the front opening portion and to form a lamp room between the transparent resin cover and the lamp body; and a light source that is disposed inside the lamp room, wherein the transparent resin cover is formed to have a flange portion for a gate, the flange portion having a linear fan gate trace on a leading edge thereof and being formed to protrude outward from an outer peripheral edge portion of the transparent resin cover. BRIEF DESCRIPTION OF THE DRAWINGS A general configuration that implements the various feature of the invention will be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention. Fig. 1 is a vertical sectional view showing a vehicle lamp according to an embodiment of the present invention. Fig. 2 is a perspective view showing a overall appearance of a resin cover illustrated in Fig. 1. Fig. 3 is a partial sectional view showing a metal mold used for injection molding, which molds the resin cover according to the embodiment. Fig. 4 is a schematic view for explaining a flow length of a molten resin in a cavity of the metal mold illustrated in Fig. 3. Fig. 5 is a partial sectional view showing a state after cutting a gate of a product taken out of the metal mold. Fig. 6 is an enlarged partial sectional view showing the vehicle lamp illustrated in ,Fig. 1. j DETAILED DESCRIPTION OF THE EMBODIMENT(S) A vehicle lamp according to an embodiment of the present invention will be described below in detail with reference to the accompanying drawings. Fig. 1 is a vertical sectional view showing the vehicle lamp according to the embodiment, and Fig. 2 is a perspective view showing an overall appearance of a resin cover illustrated in Fig. 1. The vehicle lamp 100 according to the embodiment is configured as a headlamp to be provided at a forward right side of a vehicle. As shown in Fig. 1, the vehicle lamp 100 is provided with: a lamp body 17 opened forward to have a front opening portion; and a transparent resin cover 31 attached to the front opening portion. A lamp room 15 is formed by the lamp body 17 and the resin cover 31. Inside the lamp room 15, the vehicle lamp 100 is further provided with: a discharge bulb 13 that serves as a light source; and a reflector 19 that reflects light emitted from the discharge bulb 13 toward a frontward direction. The reflector 19 is provided with an aiming mechanism (not shown) that moves the reflector 19. An extension member 10 is provided between the lamp body 17 and the resin cover 31 to cover a portion between a peripheral edge of the lamp body 17 and a peripheral edge of the reflector 19. . The discharge bulb 13 is removably attached to,a,bulb attaching hole 19a provided at a center of a rear part of the reflector 19. A connector 23 connected to a high voltage cord 21 led from a lighting circuit 20 is fitted and attached into a plug 14 of the discharge bulb 13. Although it is assumed that the discharge bulb 13 is used as a light source in the embodiment, the vehicle lamp 100 may be provided with a semiconductor light emitting device, such as an LED, or an incandescent lamp as the light source or as an additional light source. Moreover, the vehicle lamp may be configured as a so-called projector type lamp unit having a projection lens or a shade being disposed in front of the light source. The lamp body 17 is monolithically molded by a synthetic resin material. As the synthetic resin material, for example, a polycarbonate resin (a PC resin), a polycarbonate ABS resin (a PC - ABS resin) or an acrylic resin (PMMA), may be used. The lamp body 17 is formed to have a concave portion in a part corresponding to the lamp room 15 and to have a flat housing space toward a rearward direction along a side surface of the vehicle. The opening peripheral edge portion of the lamp body 17 has a sealing groove 18 opened in a forward direction of the vehicle. The sealing groove 18 serves to fit a sealing projection 32 formed on an outer peripheral edge portion of the resin cover 31 which will be described below. The resin cover 31 is molded by a transparent synthetic resin material such as a polycarbonate resin, a polycarbonate ABS resin or an acrylic resin. As shown in Fig. 1, the sealing projection 32 formed on the outer peripheral edge portion is inserted into the sealing groove 18 of the lamp body 17 and an adhesive S is filled in the sealing groove 18 so that substantially the entire area of the front opening portion of the lamp body 17 is covered by the resin cover 31 when being assembled. As shown in Fig. 2, a flange portion 33 for a gate which has a linear fan gate trace 35 on a leading edge is protruded from the outer peripheral edge portion of the resin cover 31. The flange portion 33 for a gate according to the embodiment is protruded from a curved part of an outer peripheral edge positioned on an almost center in a transverse direction on a lower side of the vehicle in the resin cover 31 in a state in which the vehicle lamp loo is attached to the vehicle. As shown in Fig. 1, a slight clearance is formed from a lower wall 31a of the resin cover 31 just below the vehicle lamp 100 and a front bumper cover 40 is thus disposed in a state in which a flange 40a formed on a rear side edge of the vehicle is held on a reinforcement 41. The lower side of the vehicle in the vehicle lamp 100 is covered with the front bumper cover 40 to be a part of the body in an attachment to the vehicle. Accordingly, when the vehicle lamp 100 is viewed from the forward direction of the vehicle, the flange portion 33 for a gate would not deteriorate an appearance of the vehicle lamp 100 in a state being attached to the vehicle. Fig. 3 is a partial sectional view showing a metal mold for injection molding which molds the resin cover according to the embodiment. Fig. 4 is a schematic view for explaining a flow length of a molten resin in a cavity of the metal mold illustrated in Fig. 3, and Fig. 5 is a partial sectional view illustrating a state brought after cutting a gate of a product taken out of the metal mold. As shown in Fig. 3, a metal mold 50 is formed by a fixed mold 51 which is fixed to an injection molding machine (not shown) and a movable mold 52 that is moved to open the metal mold 50. A cavity C for molding the resin cover 31 is formed on a metal mold dividing surface (a parting line) of the fixed mold 51 and the movable mold 52. A molten resin (a PC resin) is filled in the cavity C through a sprue S and a runner L which are bonded to a nozzle of the injection molding machine, and a fan gate G is provided on a joint of the cavity C and the runner L. As shown in Figs. 3 and 4, the fan gate G substantially has a shape of an isosceles triangle, and communicates with the runner L in a top part thereof and is opened into the cavity C taking a corresponding shape to the resin cover 31 in a bottom side part. The molten resin injected from the nozzle of the injection molding machine flows into the fan gate G through the sprue S and the runner L and passes through the fan gate G, and is then injected into the cavity C and is thereafter cooled and solidified in the mold. Consequently, it is possible to obtain the resin cover 31 taking a corresponding sh^e to the cavity C. For a dimension of the fan gate G corresponding to the resin cover 31 according to the embodiment, it is preferable that a gate width w should be equal to or greater than at least 30 mm and a gate thickness d should be equal to or greater than at least 2.5 mm. The dimension of the fan gate G is properly set depending on a size of a resin cover to be molded. It is apparent that a smaller fan gate than the dimension of the fan gate G is used when the resin cover to be molded is smaller than the resin cover 31 according to the embodiment. Furthermore, the fan gate G according to the embodiment is designed to be positioned at the tip of the cavity C taking a corresponding shape to the flange portion 33 for a gate which is protruded from the outer peripheral edge portion of the resin cover 31 to be molded. Even if a gate position of the fan gate G is placed on the curved part in the outer peripheral edge portion of the resin cover 31 as shown in Fig. 4, it is possible to set the fan gate G to the cavity C of the metal mold through the flange portion 33 for a gate which is protruded from the outer peripheral edge portion. In other words, a gate processing surface 34 can be formed to be straight over the flange portion 33 for a gate positioned in the curved part of the outer peripheral edge portion. As a result, as shown in Fig. 5, it is possible to cut the gate processing surface 34 straight also in the curved part of the outer peripheral edge portion when cutting a resin 58 solidified in the fan gate G, a resin 55 solidified in the runner L and a resin 57 solidified in the sprue S in the flange portion 33 for a gate in the resin cover (molded product) 31 taken out of the metal mold 50 for injection molding. Also in the case in which the cutting operation is performed by a cutting method using f. a water jet or a laser beam or an internal mold gate cutting method, therefore, it is possible to enhance cutting precision. In order to ensure the cutting precision in an operation for straight cutting the curved part of the resin cover 31, it is desirable that a dimension of the protrusion of the flange portion 33 for a gate should be equal to or greater than 1 mm. In other words, as shown in Fig. 4, it is possible to set the fan gate G at substantially central position in the transverse direction of the resin cover 31 in which flow lengths (distances from the fan gate G to left and right flow ends) LI and L2 of the molten resin are the shortest irrespective of the shape of the outer peripheral edge portion. Thus, it is possible to reduce a pressure loss of an injection pressure, thereby molding the resin cover 31 having a small thickness. Accordingly, it is possible to provide the vehicle lamp 100 which includes the resin cover 31 taking a deformed shape and having a small thickness and weight and a large size . As shown in Fig. 6, an extended portion 18b for covering the tip of the flange portion 33 for a gate is formed on an outer sidewall 18a of the sealing groove 18 in which the adjacent sealing projection 32 to the flange portion 33 for a gate is to be fitted when the resin cover 31 is assembled into the lamp body 17. Therefore, the tip of the flange portion 33 for a gate . is covered with the extended portion 18b of the lamp body 17. Consequently, the fan gate trace 35 is not exposed to an outer part in the assembly. Thus, it is possible to prevent a burr of the fan gate trace 35 from touching a hand or finger and to inhibit an appearance from being deteriorated. In the vehicle lamp 100 according to the embodiment, the flange portion 33 for a gate is protruded from the lower i side of the vehicle in the resin cover 31 in a state in which the vehicle lamp 100 is attached to the vehicle as shown in Fig. 2. In the vehicle lamp 100, therefore, it is possible to easily hide the flange portion 33 for a gate in the bumper cover 40 to be a part of the body. Consequently, it is possible to prevent an appearance from being deteriorated in the attachment to the vehicle. In the resin cover 31, furthermore, it is possible to gradually decrease a thickness of a molded product apart from the fan gate G. As shown in Fig. 1, therefore, it is possible to gradually decrease the thickness of the resin cover 31 from the lower side of the vehicle toward the upper side of the vehicle. As a result, it is possible to easily deform an upper part of adesign surface in the resin cover31, therebyenhancing a pedestrian protecting performance of the vehicle lamp 100. By gradually decreasing the thickness of the resin bover 31 from the lower side of the vehicle toward the upper side of the vehicle, moreover, it is also possible to reduce a glare light of an emitted light. As descried above, according to the vehicle lamp of the embodiment, it is possible to m^nolithically mold the resin cover by injecting the molten resin from the fan gate positioned at the tip of the flange portion for a gate which is protruded from the outer peripheral edge portion. Also in the curved part at the outer peripheral edge portion of the resin cover, it is possible to set the fan gate into the position in which the flow length of the molten resin is the shortest. Thus, it is possible to reduce the ipressure loss of the injection pressure, thereby molding the resin cover having a small thickness. j Accordingly, it is possible to provide a vehicle lamp which includes a resin cover having a complex three-dimensional shape and having a small thickness and weight. The structures of the lamp body, the light source and the flange portion for a gate which are related to the vehicle lamp according to the present invention are not limited to the structures described above. It is to be understood that the present invention is not limited to the specific embodiment described above and that the invention can be embodied with the components modified without departing from the spirit and scope of the invention. The invention can be embodied in various forms according to appropriate combinations of the components disclosed in the embodiment described above. For example, some components may be deleted from the configuration shown as the embodiment. WHAT IS CLAIMED IS: 1. A vehicle lamp comprising: a lamp body that is formed in a shape to have a front opening portion being opened forward; a transparent resin cover that is attached to the lamp Ibody to cover the front opening portion and to form a lamp room between the transparent resin cover and the lamp body; and a light source that is disposed inside the lamp room, wherein the transparent resin cover is formed to have a flange portion for a gate, the flange portion having a linear fan gate trace on a leading edge thereof and being jformed to protrude outward from an outer peripheral edge portion of the transparent resin cover. 2. The vehicle lamp according to claim 1, wherein the lamp body comprises a sealing groove being formed along a peripheral edge at the front opening portion, wherein the transparent resin cover comprises a sealing projection being formed along a peripheral edge thereof,and wherein the lamp body comprises an outer sidewall that forms a part of the sealing groove, the outer sidewall being formed with an extended portion that covers the leading edge of the flange portion. 3. The vehicle lamp according to claim 1 or 2, wherein the flange portion is formed to protrude toward a lower side of the vehicle. |
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| Patent Number | 272504 | |||||||||
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| Indian Patent Application Number | 3164/CHE/2009 | |||||||||
| PG Journal Number | 15/2016 | |||||||||
| Publication Date | 08-Apr-2016 | |||||||||
| Grant Date | 05-Apr-2016 | |||||||||
| Date of Filing | 23-Dec-2009 | |||||||||
| Name of Patentee | KOITO MANUFACTURING CO., LTD. | |||||||||
| Applicant Address | 8-3, TAKANAWA 4-CHOME, MINATO-KU, TOKYO 108-8711 | |||||||||
Inventors:
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| PCT International Classification Number | F21W 101/10 | |||||||||
| PCT International Application Number | N/A | |||||||||
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PCT Conventions:
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