Patent Publication Number: US-2015069685-A1

Title: Structure of motor-mount for electric vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to Korean Patent Application No. 10-2013-106975, filed Sep. 6, 2013, the entire contents of which is incorporated herein for all purposes by this reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a structure of a motor-mount for an electric vehicle, and more particularly, to a structure of a motor-mount for an electric vehicle that supports a lower part of a motor of an electric vehicle in which an outer circumferential surface of a stopper comes in contact with an inner circumferential surface of a housing, a circular pressing ring coupled to an outer circumferential surface of an upper end of the stopper is further provided, and the stopper is previously compressed in a horizontal direction by the pressing ring before being forcibly inserted into the housing. 
     2. Description of Related Art 
     Vehicles equipped with a gasoline engine and a diesel engine that use fossil fuel have many problems such as environment pollution caused by an exhaust gas, global warming caused by carbon dioxide, and a respiratory disease caused by ozone production. Further, since there is a limited amount of fossil fuel on earth, the fossil fuel is in the danger of being exhausted. 
     In order to solve the problems, there have been developed electric vehicles such as a pure electric vehicle (EV) that travels by driving a driving motor, a hybrid electric vehicle (HEV) that travels by an engine and a driving motor, and a fuel cell electric vehicle (FCEV) that travels by driving a driving motor by a power generated in a fuel cell. 
     In general, the engine of the vehicle constantly generates vibration and generates vibration in all directions by a combination of various factors depending on bumps in the road during traveling of the vehicle. 
     Particularly, in the vehicle using the gasoline engine, a piston is operated in an order of suction, compression, explosion and exhaust through four stroke cycles to cause rotational torque of a crank shaft, and in this process, considerable vibration is generated. 
     In order to isolate such vibration, an engine-mount supporting the engine of the vehicle has been developed, and particularly, various researches for securing an isolation rate for main exciting force generated in the gasoline engine have been conducted. 
     However, unlike the vehicle using the gasoline engine, since there is no piston reciprocating motion such as explosion in the electric vehicle using the driving motor, a motor-mount needs to be changed so as to isolate shock vibration, jerk vibration, traveling vibration and gear whine noise unlike the engine-mount of the vehicle using the gasoline engine. 
     Similarly to the vehicle using the gasoline engine, in a structure of a motor-mount for an electric vehicle according to the related art, a rubber-mount structure, a hydro-mount structure and a pneumatic-mount structure are used, and  FIG. 1  illustrates a structure of a motor-mount for an electric vehicle using the rubber-mount according to the related art. 
     Although not illustrated in the drawing, the hydro-mount structure is a structure in which a fluid is accommodated below a lower part of an insulator, and is configured to allow the fluid to flow and attenuate high-frequency vibration and low-frequency vibration. However, in the hydro-mount structure, a high-frequency dynamic characteristic is less effective than that of the rubber-mount structure because of viscosity of the fluid and flow resistance. 
     The pneumatic-mount structure is a structure in which damping force is obtained by using elastic force of a material of the insulator and allowing air to flow as a working fluid. The pneumatic-mount structure includes a chamber provided with an air hole for allowing the air to enter by elastic deformation of the insulator. Since the pneumatic-mount structure is easily manufactured, the pneumatic-mount structure is mostly used in a compact vehicle. 
     As illustrated in  FIG. 1 , the rubber-mount structure is a structure in which a damping effect is obtained by using elastic force of a material of an insulator  4 , and a structure in which a bolt  1  inserted in a center of a core  2  and a motor of an electric vehicle are coupled and the insulator  4  is elastically deformed and restored along with vibration of the motor to attenuate the vibration. 
     Particularly, in the rubber-mount structure according to the related art, when a gear shift level of the gasoline engine is D, a gap is formed between a stopper  3  coupled to an outer circumferential surface of the core  2  and an inner circumferential surface of a housing  5  so as not to exhibit a high vibration characteristic. 
     However, in the electric vehicle in which there is no piston reciprocating motion, such a gap may be disadvantageous to shock and jerk, and large impact may be given to the housing when the stopper moves back and forth to cause vibration in a sear-rail of the vehicle. 
     Unlike the general gasoline vehicle of a concentrated mass, since the electric vehicle has a structure in which a mass of a vehicle body is distributed over a large area to have moment of inertia of 5 to 7 times greater than that of the general gasoline vehicle, the electric vehicle may be further adversely affected by shock or jerk. 
     The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art. 
     BRIEF SUMMARY 
     Various aspects of the present invention are directed to providing a structure of a motor-mount for an electric vehicle in which there is no gap between an outer circumferential surface of a stopper and an inner circumferential surface of a housing that come in contact with each other, the stopper is previously compressed in a horizontal direction by a pressing ring to have high stiffness in the horizontal direction before being forcibly inserted into the housing, and a fluid system is applicable to a lower part of the housing. 
     In an aspect of the present invention, a motor-mount for an electric vehicle that supports a lower part of a motor of an electric vehicle includes a core into which a bolt fastened to the motor is inserted in a center, a stopper that is coupled to surround an outer circumferential surface of the core, and is made of rubber, an insulator that is connected to a lower end of the stopper, is coupled to a lower part of the core, and has a concave lower surface, and a housing into which the core, the stopper and the insulator are forcibly inserted, and that has a cylindrical shape in which a bottom is opened. An outer circumferential surface of the stopper comes in contact with an inner circumferential surface of the housing. 
     The structure of a motor-mount for an electric vehicle may further include a circular pressing ring that is coupled to an outer circumferential surface of an upper end of the stopper. The stopper may be previously compressed in a horizontal direction by the pressing ring before being forcibly inserted into the housing. 
     An outer diameter of the stopper, which is compressed in the horizontal direction by the pressing ring before being forcibly inserted into the housing, may be relatively smaller that an inner diameter of the housing. 
     An inclined angle of an upper end surface of the stopper with respect to a horizontal axis of the stopper after being forcibly inserted into the housing may be relatively smaller than an inclined angle of the upper end surface of the stopper with respect to the horizontal axis of the stopper before being forcibly inserted into the housing. 
     The inclined angle of the upper end surface of the stopper with respect to the horizontal line of the stopper after the stopper is forcibly inserted into the housing may be between 1° and 5°. 
     The structure of a motor-mount for an electric vehicle may further include a case that is coupled to an outer circumferential surface of a lower part of the insulator, and is disposed at a lower end of the housing, a nozzle lower plate that is disposed adjacent to the lower end of the insulator to be coupled to an inner circumferential surface of the case, has a central opening to which a membrane that vibrates along with flow of a fluid is attached, and has a circular flow path formed between the opening and an outer circumferential surface of the nozzle lower plate so as to allow the fluid to flow, a circular nozzle upper plate that is disposed between the lower end of the insulator and the nozzle lower plate, and has a hole formed to open or close the flow path of the nozzle lower plate, an upper fluid chamber that is formed between the concave lower surface of the insulator and the nozzle upper plate, and accommodates the fluid therein, a lower fluid chamber that is formed between a diaphragm coupled to a lower end of the case and the nozzle lower plate, and accommodates the fluid therein, and an outer pipe that is coupled to surround an outer circumferential surface of the case. 
     According to an exemplary embodiment of the present invention, since the core, the stopper and the insulator are forcibly inserted into the housing and the outer circumferential surface of the stopper comes in contact with the inner circumferential surface of the housing, there is no gap between the stopper and the housing, impact is not given to the housing even though the stopper is moved in the horizontal direction. 
     Since the structure further includes the circular pressing ring coupled to the outer circumferential surface of the stopper and the stopper is previously pressed by the pressing ring to be compressed in the horizontal direction before being forcibly inserted into the housing, even though the stopper expands, the stopper is not separated from the housing. Further, shock generated by collision with the housing when the stopper is restored can be removed. 
     Since the inclined angle of the upper end surface of the stopper with respect to the horizontal axis of the stopper after being forcibly inserted into the housing is relatively smaller than the inclined angle of the upper end surface of the stopper with respect to the horizontal axis of the stopper before being forcibly inserted into the housing, the stopper is pressed by the pressing ring before being forcibly inserted into the housing so as to receive force in the vertical direction, and when the stopper is forcibly inserted into the housing, the stopper receives force in the horizontal direction. Accordingly, stiffness in the horizontal direction is remarkably more increased than stiffness in the vertical direction, so that shock vibration of the vehicle can be improved. 
     Since the stopper is forcibly inserted into the housing to cause force in a direction opposite to the vertical direction, even though the insulator has high hardness, it is possible to maintain low static and dynamic characteristics in the vertical direction in the structure of a motor-mount for an electric vehicle as a whole. As a result, it is possible to secure high vibration insulation performance while improving durability performance of components. 
     Since the nozzle lower plate, the nozzle upper plate, the upper fluid chamber and the lower fluid chamber are provided below the insulator to allow the accommodated fluids to flow, high-frequency vibration and low-frequency vibration can be attenuated, and it is possible to improve traveling performance of the electric vehicle. 
     It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g., fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered vehicles. 
     The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a structure of a motor-mount for an electric vehicle according to the related art. 
         FIG. 2  is a cross-sectional view of a structure of a motor-mount for an electric vehicle according to an exemplary embodiment of the present invention. 
         FIG. 3  is a cross-sectional view illustrating a state where the structure of the motor-mount for the electric vehicle is separated from a housing before being forcibly inserted into the housing according to an exemplary embodiment of the present invention. 
         FIG. 4  is a cross-sectional view illustrating an inclined angle of a pressing ring and a length of a stopper compressed before being forcibly inserted into the housing in the structure of the motor-mount for the electric vehicle according to an exemplary embodiment of the present invention. 
         FIG. 5  is a cross-sectional view for describing supporting force applied to the stopper before being completely inserted into the housing in the structure of the motor-mount for the electric vehicle according to an exemplary embodiment of the present invention. 
         FIG. 6  is a cross-sectional view for describing supporting force applied to the stopper after being completely inserted into the housing in the structure of the motor-mount for the electric vehicle according to an exemplary embodiment of the present invention. 
         FIG. 7  is a cross-sectional view illustrating a direction of supporting stiffness received by the stopper and an insulator after being completely inserted into the housing in the structure of the motor-mount for the electric vehicle according to an exemplary embodiment of the present invention. 
     
    
    
     It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment. 
     In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing. 
     DETAILED DESCRIPTION 
     Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that the present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. 
     Hereinafter, an exemplary embodiment of the present invention will be described with reference to the accompanying drawings so that those skilled in the Field of the Invention to which the present invention pertains may carry out the exemplary embodiment. 
     In an aspect of the present invention, a structure of a motor-mount for an electric vehicle that supports a lower part of a motor of the electric vehicle includes a core  10  into which a bolt  12  fastened to the motor is inserted in a center, a stopper  20  that is coupled to surround an outer circumferential surface of the core  10  and is made of rubber, an insulator  30  that is connected to a lower end of the stopper  20 , is coupled to a lower part of the core  10 , and has a concave lower surface, and a housing  40  into which the core  10 , the stopper  20  and the insulator  30  are forcibly inserted and that has a cylindrical shape in which a bottom is opened. An outer circumferential surface of the stopper  20  comes in contact with an inner circumferential surface of the housing  40 . 
     As illustrated in  FIG. 2 , the bolt  12  coupled to the lower part of the motor in order to mount the motor of the electric vehicle is vertically inserted into the center of the core  10 , and upper parts of the bolt  12  and the core  10  protrude from a top of the housing  40 . 
     When the structure of a motor-mount for an electric vehicle according to the present invention is viewed from the top as a whole, the bolt  12  and the core  10  preferably have a circular horizontal cross-section, but may have various shapes depending on a kind of the vehicle, a shape of the motor, and a fastened point of the motor and the bolt. 
     As illustrated in  FIG. 2 , the stopper  20  is coupled to the core  10  while surrounding the outer circumferential surface of the core  10 . Since the stopper  20  is made of rubber such as natural rubber or synthetic rubber, the stopper can be elastically deformed by vibration of the motor. 
     That is, when the motor of the electric vehicle is moved in a horizontal direction by vibration causing the bolt  12  and the core  10  to be moved in the horizontal direction, the vibration of the motor is attenuated by the elastic deformation of the stopper  20 . 
     As illustrated in  FIG. 2 , the insulator  30  is connected to a lower end of the stopper  20 . Further, the insulator  30  is coupled to the lower part of the core  10 , and the concave lower surface thereof forms a space for accommodating an upper fluid chamber  90  to be described below. 
     In the illustrated exemplary embodiment, the stopper  20  and the insulator  30  are connected to each other so as to have an “X”-shaped vertical cross-section as a whole. Similarly to the stopper  20 , the insulator  30  is also made of rubber to isolate the vibration of the motor. 
     Similarly to the bolt  12  and the core  10 , when the structure of a motor-mount for an electric vehicle according to the present invention is viewed from the top as a whole, the stopper  20  and the insulator  30  preferably have circular horizontal cross-sections, but may have various shapes depending on various factors. 
     As illustrated in  FIG. 2 , the core  10  is coupled to an upper center of the housing  40 , and the housing has a cylindrical shape in which the bottom is opened. The inner circumferential surface of the housing  40  comes in contact with the outer circumferential surface of the stopper  20 . 
     As illustrated in  FIG. 1 , in the structure of a motor-mount for an electric vehicle according to the related art, since a predetermined gap is formed between the stopper  3  and the housing  5 , when torque is input to or output from the motor, the stopper  3  and the housing  5  collide with each other to cause shock vibration. However, in the structure of a motor-mount for an electric vehicle according to the present invention, since there is no gap between the stopper  20  and the housing  40 , the shock vibration is decreased. 
     As illustrated in  FIG. 2 , the structure of a motor-mount for an electric vehicle according to the present invention further includes a circular pressing ring  50  coupled to an outer circumferential surface of an upper end of the stopper  20 . The stopper  20  is preferably compressed in the horizontal direction in advance by the pressing ring  50  before being forcibly inserted into the housing  40 . 
     As illustrated in  FIG. 3 , the bolt  12 , the core  10 , the stopper  20  and the insulator  30  are coupled to each other to be forcibly inserted into the housing  40 . At this time, the stopper is compressed toward its center in the horizontal direction by the pressing ring  50  as a whole before being forcibly inserted into the housing  40 . 
     Since an outer diameter of the stopper  20 , which is compressed by the pressing ring  50  before being forcibly inserted into the housing  40 , is relatively smaller than an inner diameter of the housing  40 , the stopper is inserted into the housing with ease. Specifically, it is preferred that the outer diameter of the stopper  20  before being forcibly inserted be 86 mm and the inner diameter of the housing  40  be 88 mm, but may have various dimensions. 
     As illustrated in  FIG. 4 , the pressing ring  50  that compresses the stopper  20  before being forcibly inserted into the housing  40  has a predetermined inclined angle with respect to a horizontal axis of the stopper  20 , and may have an inclined angle of about 45°. 
     A length of the stopper  20 , which is a straight-line distance between the pressing ring  50  and an end of the stopper  20  at which the stopper before being forcibly inserted into the housing  40  is coupled to the core  10 , may be 18 mm or other suitable dimension. 
     As illustrated in  FIGS. 5 and 6 , it is preferred that an inclined angle of an upper end surface of the stopper  20  with respect to the horizontal axis of the stopper  20  after the stopper  20  is forcibly inserted into the housing  40  be relatively smaller than an inclined angle of the upper end surface of the stopper  20  with respect to the horizontal axis of the stopper before being forcibly inserted into the housing  40 . 
     Specifically, the inclined angle of the upper end surface of the stopper  20  with respect to the horizontal line of the stopper  20  before the stopper  20  is forcibly inserted into the housing  40  is preferably about 45°, and the inclined angle of the upper end surface of the stopper  20  with respect to the horizontal line of the stopper  20  after the stopper  20  is completely inserted into the housing  40  is preferably 1° or more and 5° or less. 
     The length of the stopper  20 , which is the straight-line distance between the pressing ring  50  and the end of the stopper  20  at which the stopper after being forcibly inserted into the housing  40  is coupled to the core  10 , is preferably 13 mm or other suitable dimension. 
     As illustrated in  FIG. 5 , the stopper  20  is pressed by the pressing ring  50  so as to receive supporting force in a vertical direction before the stopper  20  is forcibly inserted into the housing  40 . However, as illustrated in  FIG. 6 , when the stopper  20  is forcibly inserted into the housing  40 , the stopper  20  gradually receives the supporting force in the horizontal direction. 
     As stated above, since the stopper receives the supporting force in the horizontal direction, stiffness in the horizontal direction can be increased 3.5 times greater than stiffness in a vertical direction, and it is possible to prevent the stopper  20  from being separated from the housing  40 . 
     When the stopper  20  and the insulator  30  having high hardness are generally used, durability performance of components is improved. However, since a static characteristic and a dynamic characteristic are increased, vibration isolation performance is degraded, so that the stopper  20  and the insulator  30  having low hardness need to be used. Accordingly, the durability performance of the components may be degraded. 
     However, as illustrated in  FIG. 7 , in the structure of a motor-mount for an electric vehicle according to the present invention, since the stopper  20  is forcibly inserted into the housing  40  to generate force in a vertical lower direction, even though the stopper  20  having high hardness is used, it is possible to maintain low static and dynamic characteristics in the vertical direction. 
     For example, in the structure of a motor-mount for an electric vehicle according to the present invention, when the stopper  20  is compressed within the housing  40 , the stopper  20  has a supporting stiffness of −10 kgf/mm in the vertical lower direction (in a direction of {circle around ( 1 )} in  FIG. 7 ), and the insulator  30  has a supporting stiffness of +30 kgf/mm in a vertical upper direction (in a direction of {circle around ( 2 )} in  FIG. 7 ). Accordingly, a total supporting stiffness is +20 kgf/mm in the vertical upper direction. 
     The structure of a motor-mount for an electric vehicle according to the present invention can improve insulation performance by 30% or more than that of the structure of a motor-mount for an electric vehicle of the related art in which the insulator  4  has a supporting stiffness of +20 kgf/mm in the vertical upper direction in order to have the total supporting stiffness of +20 kgf/mm in the vertical upper direction. 
     As illustrated in  FIG. 2 , the structure of a motor-mount for an electric vehicle according to the present invention preferably further includes a case  60  that is coupled to an outer circumferential surface of a lower part of the insulator  30  and is disposed at a lower end of the housing  40 , a nozzle lower plate  80  that is disposed adjacent to a lower end of the insulator  30  to be coupled to an inner circumferential surface of the case  60 , has a central opening  84  to which a membrane  82  that vibrates along with flow of a fluid can be attached, and has a circular flow path  86  formed between the opening  84  and an outer circumferential surface so as to allow the fluid to flow, a circular nozzle upper plate  70  that is disposed between the lower end of the insulator  30  and the nozzle lower plate  80  and has a hole  72  formed to open or close the flow path  86  of the nozzle lower plate  80 , an upper fluid chamber  90  that is formed between the concave lower surface of the insulator  30  and the nozzle upper plate  70  and accommodates the fluid therein, a lower fluid chamber  92  that is formed between a diaphragm  94  coupled to the lower end of the case  60  and the nozzle lower plate  80  and accommodates the fluid therein, and an outer pipe  62  that is coupled to surround an outer circumferential surface of the case  60 . 
     As illustrated in  FIG. 2 , the case  60  has a cylindrical pipe shape in which an upper surface and a lower surface coupled to the outer circumferential surface of the lower part of the insulator  30  are opened, and is disposed right below the lower end of the housing  40 . 
     As illustrated in  FIG. 2 , the nozzle lower plate  80  has a substantially circular shape in which the opening  84  to which the membrane  82  can be attached is formed, and the circular flow path  86  is formed between the opening  84  and the outer circumferential surface of the nozzle lower plate  80  to allow the fluid to flow. 
     The fluid may flow through the flow path  86  formed in the nozzle lower plate  80  as described above, or may flow through a gap of the opening  84  to which the membrane  82  is attached. Vibration transferred to the structure of a motor-mount for an electric vehicle is attenuated by the flow of the fluid. 
     As illustrated in  FIG. 2 , the circular nozzle upper plate  70  having the hole  72  for opening or closing the flow path  86  of the nozzle lower plate  80  is disposed between the lower end of the insulator  30  and the nozzle lower plate  80 , and the amount of the fluid flowing through the flow path  86  of the nozzle lower plate  80  is adjusted through the hole  72 . 
     The upper fluid chamber  90  that accommodates the fluid therein is formed between the nozzle upper plate  70  and the lower surface of the insulator  30 , and the lower fluid chamber  92  that accommodates the fluid is formed between the diaphragm  94  coupled to the lower end of the case  60  and the lower surface of the nozzle lower plate  80 . 
     When the vibration is transferred through the motor of the vehicle in operation, the fluid accommodated in the upper fluid chamber  90  flows through the flow path  86  formed in the nozzle lower plate  80  or flows to the lower fluid chamber  92  through the gap of the opening  84  to which the membrane  82  is attached, so that the vibration of the motor is attenuated. 
     Accordingly, the structure of a motor-mount for an electric vehicle according to the present invention is a structure in which both a rubber-mount structure including the stopper  20  and the insulator  30  and a hydro-mount structure including the upper fluid chamber  90  and the lower fluid chamber  92  are used to remarkably improve traveling performance of the vehicle. 
     The present invention described above is not to be restricted by the aforementioned exemplary embodiments and the accompanying drawings. It is to be appreciated that those skilled in the art can variously substitute, change or modify the embodiments without departing from the technical spirit of the present invention. 
     For convenience in explanation and accurate definition in the appended claims, the terms “upper”, “lower”, “inner” and “outer” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. 
     The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.