Patent Publication Number: US-2012043839-A1

Title: Connecting structure for relay terminal

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a connecting structure for relay terminal. 
     2. Description of the Related Art 
     Devices such as a motor fixed to an engine and an inverter are mounted in a hybrid vehicle. The motor is connected to the inverter by a wiring harness such as a power cable. 
     U.S. Patent Application Publication No. 2004/0124332 and  FIG. 10  herein show a known structure in which a motor  1  and an inverter  2  are untied for space saving and are connected electrically by relay terminals  3 . The relay terminals  3  are in the form of straight bars and directly connect three motor terminals  5  on the motor  1  and three inverter terminals  6  on the inverter  2 . In this way, a wiring harness for connecting the motor  1  and the inverter  2  can be omitted. 
     The motor  1  is fixed to an engine and vibration from the engine is transmitted directly to the relay terminal  3  via the motor  1 . Vibration generated from the inverter  2  also is transmitted directly to the relay terminals  3 . The vibrations from the engine and from the inverter  2  have different frequencies. Thus, vibrations having different frequencies are transmitted simultaneously to the relay terminals  3 . Resonance occurs at or near the natural frequency of the relay terminals  3  and metal fatigue progresses. As a result, there is a problem of crack and cut. 
     The invention was developed in view of the above situation and an object thereof is to improve lifetime of a relay terminal. 
     A further object of the invention is to suppress damage of a relay terminal due to metal fatigue and to improve the lifetime of a relay terminal by absorbing vibrations transmitted from devices. 
     SUMMARY OF THE INVENTION 
     The invention relates to a connecting structure for a relay terminal made of an enameled wire. The connecting structure is adapted to electrically connect a first device side terminal on a first device to a second device side terminal on a second device. The relay terminal comprises: a first connecting portion to be connected to the first device side terminal; a second connecting portion to be connected to the second device side terminal; and at least one vibration absorbing portion electrically conductively connecting the first and second connecting portions. The vibration absorbing portion has a wound configuration. 
     The vibration absorbing portion may be spirally wound about a line connecting the first and second connecting portions as an axial center. 
     The spirally wound vibration absorbing portion of the above-described relay terminal connecting structure absorbs vibrations transmitted to the relay terminal from the first and second device side terminals and hence suppresses damage to the relay terminal due to metal fatigue. 
     A plurality of relay terminals may be provided and may be arranged so that the positions of the axial centers of the respective vibration absorbing portions substantially align. For example, the plural vibration absorbing portions may be arranged in series in a vertical direction so that the positions of the axial centers of the respective vibration absorbing portions substantially align. Thus, an area taken up by the vibration absorbing portions can be reduced in a lateral direction as compared with the case where the vibration absorbing portions are juxtaposed in the lateral direction. 
     The vibration absorbing portion may comprise at least one coil spring extending in a direction of the axial center of the vibration absorbing portion. Accordingly, vibrations transmitted from the first and second devices can be absorbed by resilient deformation of the coil spring in the direction of the axial center. Thus, the relay terminal is not likely to be damaged by metal fatigue. 
     The enamel wires may be arranged at intervals in a circumferential direction about the axial centers of the vibration absorbing portion in a cross section of the vibration absorbing portion perpendicular to the direction of the axial centers. Thus, for example, in the case of three relay terminals, three coil springs are wound spirally together. This enables an area taken up by the coil springs to be reduced in the vertical direction as compared with the case where the coil springs are arranged in series in the vertical direction. 
     The first device may comprise a three-phase motor fixed to an engine and the first device side terminal may be three motor side terminals provided on the three-phase motor. The second device may comprise an inverter and the second device side terminal may be three inverter side terminals provided on the inverter. Corresponding pairs of the motor side terminals and the inverter side terminals may be connected individually by three relay terminals. Thus, the relay terminals of the invention can connect the three-phase motor and the inverter having different vibration frequencies. 
     The first connecting portion may be fastened to the first device side terminal and fixed to a portion of a terminal block by inserting a fastening bolt through a bolt insertion hole of the first device side terminal and the inside of the first connecting portion and tightening the fastening bolt to the terminal block. The second connecting portion may be fastened to the second device side terminal and fixed to a portion of the terminal block particularly by inserting a fastening bolt through a bolt insertion hole of the second device side terminal and the inside of the second connecting portion and tightening the fastening bolt to the terminal block. 
     The vibration absorbing portion may be arranged near a side surface of a terminal block. 
     The first and second connecting portions may include first and second relay wires bent at an angle and preferably substantially perpendicularly after extending substantially straight up to a side surface of a terminal block. 
     The vibration absorbing portion preferably is covered at least partly by a protection cover. The protection cover may be mounted to a terminal block by tapping screws inserted through respective mounting pieces. 
     At least one slit may be formed in the protection cover to accommodate at least one first relay wire extending from the first connecting portion. The slit may be dimensioned so that small clearances are formed between the first relay wire and an edge of the slit. 
     The vibration absorbing portion may comprise plural coil springs wound spirally together with their axial centers substantially aligned to define a plural spiral structure. The coil springs may substantially have equal diameters. 
     These and other features and advantages of the invention will become more apparent upon reading the following detailed description of preferred embodiments and accompanying drawings. It should be understood that even though embodiments are separately described, single features thereof may be combined to additional embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of three relay terminals of a first embodiment juxtaposed between a motor and an inverter with a protection cover partly in section. 
         FIG. 2  is a plan view showing the three relay terminals of the first embodiment juxtaposed between the motor and the inverter. 
         FIG. 3  is a bottom view of the state of  FIG. 2 . 
         FIG. 4  is a side view of the relay terminals of the first embodiment arranged between the motor and the inverter with the protection cover partly in section. 
         FIG. 5  is a front view of relay terminals of a second embodiment arranged between a motor and an inverter with a protection cover partly in section. 
         FIG. 6  is a plan view showing the relay terminals of the second embodiment arranged between the motor and the inverter. 
         FIG. 7  is a bottom view showing the state of  FIG. 6 . 
         FIG. 8  is a side view of the relay terminals of the second embodiment arranged between the motor and the inverter with the protection cover partly in section. 
         FIG. 9  is an enlarged section showing coil spring parts of  FIG. 6  cut in a direction perpendicular to a direction of axial centers. 
         FIG. 10  is a partial section of a prior art relay terminal mounting structure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 1 to 4  illustrate a first embodiment of a connecting structure for relay terminals  10  that electrically connect a motor  50  fixed to an unillustrated engine and an inverter  60 . The connecting structure preferably is used in a vehicle, such as a hybrid vehicle or an electric vehicle. 
     The motor  50  and the inverter  60  are housed in the same case (not shown) and are partitioned by an unillustrated partition wall. The motor  50  is used in the housing with a fluid for cooling (e.g. ATF) showered thereon. 
     The motor  50  includes three motor side terminals  51 , as shown in  FIGS. 1 and 4 . Each motor side terminal  51  is formed with a bolt insertion hole  51 A through which a fastening bolt V is insertable. 
     Similarly, the inverter  60  includes three inverter side terminals  61 . Each inverter side terminal  61  is formed with a bolt insertion hole  61 A, through which a fastening bolt V is insertable. 
     The relay terminals  10  are formed by bending enameled wires and, in this embodiment, three relay terminals  10  are juxtaposed in a lateral direction, as shown in  FIG. 1 . 
     Each relay terminal  10  includes a motor side annular connecting portion  11  located at a first distal end (e.g. a lower end) and an inverter side annular connecting portion  12  located at a second distal end (e.g. an upper end) as shown in  FIG. 1 . 
     The motor side annular connecting portion  11  and the inverter side annular connecting portion  12  are annular and have insulation coatings removed therefrom to expose conductors, as shown in  FIGS. 2 and 3 . 
     The fastening bolts V are insertable through the insides of the motor side annular connecting portions  11  and the inverter side annular connecting portions  12 . 
     As shown in  FIGS. 1 and 3 , each motor side annular connecting portion  11  is fastened to the motor side terminal  51  and fixed to the lower surface of a terminal block P by inserting the fastening bolt V through the bolt insertion hole  51 A of the motor side terminal  51  and the inside of the motor side annular connecting portion  11  and tightening the fastening bolt V to the terminal block P provided on the partition wall. Similarly, each inverter side annular connecting portion  12  is fastened to the inverter side terminal  61  and fixed to the upper surface of the terminal block P by inserting the fastening bolt V through a bolt insertion hole  61 A of the inverter side terminal  61  and the inside of the inverter side annular connecting portion  12  and tightening the fastening bolt V to the terminal block P as shown in  FIGS. 1 and 3 . 
     Note that three bolt holes P 1  are formed side by side in the lateral direction in each of the upper and lower end surfaces of the terminal block P and the respective motor side terminals  51  and the respective inverter side terminals  61  are to be fixed to the terminal block P. 
     The relay terminals  10  electrically connect the motor side terminals  51  and the inverter side terminals  61  by being fixed at outer ends of the terminal block P by the fastening bolts V. Note that the motor side terminals  51  and the inverter side terminals  61  are arranged so that the corresponding pairs of the terminals  51 ,  61  are aligned (particularly vertically) and are connected individually by the respective relay terminals  10  juxtaposed in the lateral direction, as shown in  FIG. 1 . 
     Each motor side annular connecting portion  11  includes a motor side relay wire  11 A that extends straight to a side surface of the terminal block P and then is bent substantially perpendicularly up and each inverter side annular connecting portion  12  includes an inverter side relay wire  12 A that extend straight to the side surface of the terminal block P and then is bent substantially perpendicularly down, as shown in  FIG. 4 . 
     A resilient vibration absorbing coil spring  13  extends unitarily between the motor side relay wire  11 A of the motor side annular connecting portion  11  and the inverter side relay wire  12 A of the inverter side annular connecting portion  12  of each relay terminal  10 . The coil springs  13  are arranged near the side surface of the terminal block P and are covered at least partly by a protection cover  70  made e.g. of synthetic resin. 
     As shown in  FIGS. 2 and 4 , the protection cover  70  includes a substantially rectangular covering portion  71  that is open at an upper side and a side facing the terminal block P. Two mounting pieces  72  are provided at the opposite lateral edges of an opening of the covering portion  71 . 
     Three slits  73  are formed in the lower end surface of the covering portion  71  and accommodate the three respective motor side relay wires  11 A extending from the motor side annular connecting portions  11 . As shown in  FIG. 3 , the slits  73  are dimensioned so that small clearances are formed between the motor side relay wires  11 A and edges of the slits  73 , thereby making it difficult for ATF oil and the like in the motor  50  to enter the covering portion  71 . Note that a measure to prevent oil such as an unillustrated cover is taken at a lower part of the protection cover  70  so that ATF oil and the like do not enter through the clearances between the motor side relay wires  11 A and the slits  73 . 
     Tapping screws T are inserted through the mounting pieces  72  and tightened to the side surface of the terminal block P for fixing the protection cover  70  to the terminal block P. 
     As shown in  FIGS. 2 and 4 , each coil spring  13  is wound spirally in a clockwise direction at a substantially uniform pitch from an upper end near the inverter  60  to a lower end near the motor  50  and is concentric about an imaginary straight line connecting the inverter side relay wire  12 A and the motor side relay wire  11 A. The coil spring  13  is resiliently deformable in a vertical direction and hence can expand or contract from a normal unbiased length. 
     The relay terminals  10  are connected directly to the motor side terminals  51  and the inverter side terminals  61 . Thus, vibrations generated by the unillustrated engine fixed to the motor  50  and to the inverter  60  are transmitted directly to the relay terminals  10 . The relay terminals  10  are subject to the vibration transmitted from the motor  50  and from the inverter  60  until the vehicle stops and hence the relay terminals  10  vibrate constantly. 
     Further, high-frequency vibration of the engine transmitted via the motor  50  and low-frequency vibration transmitted from the inverter  60  differ in frequency so that the relay terminals  10  vibrate irregularly. However, the coil springs  13  are wound spirally in central parts of the relay terminals  10 . Accordingly, vertical resilient deformations of the coil springs absorb vibrations at both upper and lower ends of the relay terminals  10  to suppress damage, such as cracks and cuts, due to metal fatigue. 
     Relay terminals  20  of a second embodiment of the invention are illustrated in  FIGS. 5 to 9 . The relay terminals  20  differ from the relay terminals  10  of the first embodiment with respect to parts of the coil springs  13 , the motor side relay wires  11 A and the inverter side relay wires  12 A. Elements of the second embodiment that are the same as or similar to the first embodiment are identified by the same reference numerals, but are not described again. The relay terminals  20  of the second embodiment have three coil springs  14  of equal diameters spirally wound around the same axial center to define a triple spiral structure. More specifically, as shown in  FIG. 5 , respective relay wires  15  extending from motor side annular connecting portions  11  at the opposite ends and inverter side relay wires  16  extending from inverter side annular connecting portions  12  at the opposite ends are pulled toward the three coil springs  14  that are wound spirally together. Windings of the coil springs  14  are in plural (e.g. three) levels so that pitches of the coil springs  14  are substantially uniform. 
     The enameled wires are arranged at substantially equal intervals in a circumferential direction about the axial centers of the coil springs  14 , in a cross section perpendicular to the axial centers of the coil springs  14  shown in  FIG. 9 . 
     Spirally winding the coil springs  14  of the relay terminals  20  together reduces the width of a covering portion  75  of a protection cover  74  covering the coil springs  14  to less than about half (particularly about ⅓) and one slit  76  is formed in the bottom surface of the covering portion  75 . Thus, the inverter side relay wires  16  extending from the lower ends of the respective coils  14  are pulled out from the slit  76  so as not to overlap each other, as shown in  FIG. 7 . 
     Generally, restriction on an arrangement space for electronic parts in a case uniting the motor  50  and the inverter  60  is quite large and great importance is attached to the saving of a space taken up by the relay terminals. This second embodiment reduces an area for arranging the coil springs  14 , including the protection cover  74 , to about ⅓ in the lateral direction as compared with the first embodiment. 
     In this way, it becomes possible to save the space taken up by the relay terminals  20  in the lateral direction and to absorb vibrations transmitted from the motor side terminals  51  and the inverter side terminals  61 . 
     The invention is not limited to the above described and illustrated embodiments. For example, the following embodiments are also included in the technical scope of the present invention. 
     The coil springs of the relay terminals are covered by the protection cover that is open at the upper side and the side facing the terminal block P in the above embodiments. However, the invention is not limited to such a mode. For example, the coil springs may be covered by a protection cover covering the entire outer peripheral surfaces of the coil springs in the relay terminals or a protection cover that is open only at the side facing the terminal block P. 
     The coil springs  13  of the relay terminals  10  are wound spirally in the clockwise direction in the first embodiment. However, all or some of the coil springs  13  of the relay terminals  10  may be wound spirally in a counterclockwise direction. 
     The coil springs  14  of the three relay terminals  20  of the second embodiment are wound spirally together in the clockwise direction. However, the coil springs  14  of the three relay terminals  20  may be wound spirally together in the counterclockwise direction. 
     The coil springs  14  of the three relay terminals  20  are wound spirally together in the second embodiment. However, coil springs of more or fewer relay terminals may be wound spirally together. 
     The coil springs of the relay terminals are wound spirally at substantially equal pitches in the above embodiments. However, the spiral winding pitches may be irregular. 
     The motor side annular connecting portions  11  and the inverter side annular connecting portions  12  are fixed to the same terminal block P in the above embodiments. However, the motor side annular connecting portions  11  and the inverter side annular connecting portions  12  may be fixed respectively to different terminal blocks. 
     The coil springs  14  of the three relay terminals  20  are wound spirally together in the second embodiment. However, coil springs having different diameters may be arranged in concentric circles. 
     The central parts of the relay terminals  10 ,  20  are formed into the coil springs in the above embodiments. However, the central parts of the relay terminals may be formed to have a conical spiral structure (spiral structure like a conch).