Sealing arrangement, electrical cable for a drive motor and a sealing method for it

Abstract

The electrical cable 114 comprises several conductors 102, each with its own insulation, all covered by the sheath 108. The sealing arrangement 100 comprises a sealing element 112, a first section 106 with an inlet, and a second section 104 with several outlets. The sealing element 112 is slidably inserted over the electrical cable 114 through the first section 106 such that the first section 106 covers the sheath 108 and the several conductors 102 of the electrical cable 114 pass through the several outlets of the second section 104. The sealing element 112 is made of heat-shrink tubing, which, when heat is applied, shrinks the first section 106 and the second section 104 and seals all gaps therein, characterized in that at least one airflow path 110 is formed between the first section 106 and the sheath 108 of the electrical cable 114.

Description

In the following specification, the nature of this invention and the manner in which it is practiced will be described and specified:Field of the InventionThe present disclosure relates to a sealing assembly for an electric cable of a drive motor, an electric cable for the drive motor, and a method for sealing the electric cable.BACKGROUND OF THE INVENTIONIn drive motors for two-wheel vehicles and other types of vehicles, water ingress into drive motors is a serious problem. It may result in beginning malfunctions and rust inside the engine, followed by engine seizure. In the existing construction, the water cannot enter from the motor portion (gaskets, shaft, cover, etc.), but the wire harness connecting the motor to the motor control unit is not IP67 certified. The wire harness is intentionally supported so as to ensure durability of the engine in consideration of the advantages of the breathing characteristic. However, at present, breathability also leads to water entering the engine during heavy rain / high pressure water washing.The solution currently in use on the market is to inject adhesive into the opening of the harness to a certain depth (up to 5 cm) to seal the terminal end 204 of the electrical cable 114. However, this solution has a concern in durability, and the effectiveness depends solely on the quality of the adhesive used. This concept also completely seals the motor, thereby removing the breathing function of the harness. The adhesive must also survive road vibrations, high temperature operation (>100 °C), and its effectiveness over the life of the engine is not currently known. Gel-filled wiring harnesses are also available but are rarely used because they are expensive.According to a prior art, DE2927558 discloses a watertight handle and cable termination - with stripped conductors and sheath enclosed and vulcanized, as well as the handle for the device. A handle and a watertight connection for the supply of electrical devices, in particular for the instrumentation of motor vehicles. The terminal includes a thermoplastic grommet vulcanized onto the end of the electrical lead and having a sleeve-like portion as an extension for each individual insulated conductor in the cable. The cable is inserted into the end of the sleeve sleeve so that the outer jacket of the cable is provided with a handle and protected. Each insulated single line string is stripped so that the insulated part leads forward into the extensions of the bushing unit. The stripped cord extending from the grommet extensions are further protected by boots which are slid over the ends and bonded or vulcanized to the main grommet unit. The outer surface of the bushing sleeve is of annular configuration in order to enable a vulcanized seal with respect to the housing of the device at the entry point.Brief Description of the Accompanying DrawingsAn embodiment of the disclosure will be described with reference to the following accompanying drawings, in which:, FIG. 1 illustrates an electric cable sealing structure of a drive motor according to an embodiment of the present invention; FIG. 2 is a perspective view of the assembled electric cable seal of the drive motor according to an embodiment of the present invention; and FIG. 3 illustrates a flow chart of a method for sealing an exposed end of the electric cable of the drive motor according to the present invention.Detailed Description of EmbodimentsFIG. 1 illustrates an electric cable sealing structure of a drive motor according to an embodiment of the present invention. The electrical cable 114 includes a plurality of conductors 102 having respective insulation and all covered by a sheath 108 (also known as an outer sheath). The plurality of conductors 102 are partially exposed from the insulation and the jacket 108 for connection to a battery, control unit of the vehicle. The sealing assembly 100 includes a sealing member 112 (also known as a breakout boat), a first portion 106 having an inlet, and a second portion 104 having multiple outlets. The sealing member 112 is slidably inserted over the electrical cable 114 through the first portion 106 such that the first portion 106 covers the jacket 108 of the electrical cable 114 and the plurality of conductors 102 of the electrical cable 114 pass through the plurality of outlets of the second portion 104. The sealing member 112 is made of heat shrink tubing that shrinks the first portion 106 and the second portion 104 upon application of heat and seals a gap between the sealing member 112 and the electrical cable 114 (and all gaps therein), characterized in that at least one airflow path 110 is formed between the first portion 106 of the sealing member 112 and the jacket 108 of the electrical cable 114.Two views are shown in FIG. 1. A first view 116 shows the sealing member 112 attached to an open / terminal end 204 (shown in FIG. 2 ) of the electrical cable 114. A second view 118 shows a cross-sectional view of the sealing member 112 attached to the open / terminal end 204 of the electrical cable 114. The electrical cable 114 is a multi-core cable having at least two or more conductors 102. The conductors 102 are insulated and partially stripped at the open / terminal end 204 to which a connection is to be made. Thus, the conductor 102, insulator, and jacket 108 are collectively referred to as the electrical cable 114. An air gap is present between the jacket 108 and the conductors 102 that is present over the entire length of the electrical cable 114.According to an embodiment of the present invention, the at least one airflow path 110 extends along the first portion 106 and communicates with the air gap within the electrical cable 114. According to another embodiment, before applying heat, an adhesive material is filled between the sealing member 112 and the electric cable 114. According to yet another embodiment, at least one air flow path 110 is formed in a straight line or curved line. The at least one airflow path 110 starts at the input end of the first portion 106, extends within or within the first portion 106 to the beginning of the second portion 104, and then connects to the air gap of the electrical cable 114.According to an embodiment of the present invention, the at least one airflow path 110 is formed by inserting a member (not shown) between the first portion 106 of the sealing member 112 and the jacket 108 of the electrical cable 114 prior to application of heat and removing the member after application of heat. The element functions as a place holder which is positioned before the application of heat and then extracted after the heat shrinking process is completed according to requirement.According to an embodiment of the present invention, the electric cable 114 is provided to the drive motor, or the drive motor is provided to the electric cable 114. The electrical cable 114 includes a plurality of conductors 102 having respective insulation and all covered by the jacket 108. The plurality of conductors 102 are partially exposed for connection from the insulation and the jacket 108. The electrical cable 114 includes the sealing member 112 (also known as a breakout boat) having the first portion 106 with the inlet and the second portion 104 with multiple outlets. The sealing member 112 is slidably inserted over the electrical cable 114 through the first portion 106 such that the first portion 106 covers the jacket 108 of the electrical cable 114 and the partially exposed plurality of conductors 102 pass through the plurality of outlets of the second portion 104. The sealing member 112 is made of heat shrink tubing that shrinks and seals each gap therein or upon which it is inserted upon application of heat, the first portion 106 and the second portion 104, characterized in that the at least one airflow path 110 is formed between the first portion 106 of the sealing member 112 and the jacket 108 of the electrical cable 114.According to an embodiment of the present invention, the at least one air flow path 110 is formed in one of the straight line and the curved line. The at least one airflow path 110 is in communication with the air gap within the electrical cable 114. According to another embodiment, the adhesive material is filled between the sealing member 112 and the electric cable 114 before application of heat. According to yet another embodiment, the at least one airflow path 110 is formed by inserting the element between the first portion 106 of the sealing member 112 and the jacket 108 of the electrical cable 114 prior to application of heat and removing the element after application of heat.According to an embodiment of the present invention, each of the air flow paths 110 is formed with a diameter of 1 millimeter. In another embodiment, the at least one airflow path 110 includes two airflow paths 110 formed on diametrically opposite sides of the electrical cable 114. The size of the opening of the at least one airflow path 110 and the number of airflow paths 110 are designed according to requirement and not limited to the example provided.According to an embodiment of the present invention, the drive motor is any one selected from a group comprising a hub motor or laterally mounted motor (with neodymium magnet), or as a motor mounted on the wheel of an electric or hybrid vehicle.FIG. 2 illustrates a perspective view of the assembled electric cable seal of the drive motor according to an embodiment of the present invention. The multi-core conductor 102 is shown in four times, but this is not to be understood as limiting. The multi-core cable may include two or more conductors 102. In FIG. 2, the at least one airflow path 110 is explicitly shown. The terminal end 204 of the electrical cable 114 is remote from an opening 202 of the at least one airflow path 110.According to an embodiment of the present invention, an application of the sealing assembly 100 is provided. It is assumed that the sealing member 112 is filled with a gel-based adhesive. The sealing member 112 includes an inlet and a plurality of outlets. Upon heating of the sealing member 112 (which is the heat shrink tube), the sealing member 112 shrinks and bonds firmly to the surface of the electrical cable 114. The sealing member 112 ensures that there are no open gaps through which water can enter the electrical cable 114. The adhesive gel within the sealing member 112 ensures that individual outlets (or breakouts) are well sealed upon shrinkage. This sealing member 112 works very well in operation at high temperature and does not pose a risk of water ingress.According to the present invention, a method of sealing using the sealing member 112 is provided. A first step involves mounting the gel-filled sealing member 112 (heat shrink tube) prior to mounting the electrical cable 114. A next step involves sealing the sealing member 112 to the electrical cable 114 using the heat shrinking process. The heat shrinking process is controlled so that after heating there is sufficient clearance at the entrance part. This maintains the breathability of the electric cable 114 of the drive motor. The electrical cable 114 or drive motor is leak tested at the end of the motor mounting line to ensure that the sealing member 112 is fully sealed. The specific steps are set forth in FIG. 3.FIG. 3 illustrates a flow chart of a method for sealing an exposed end of the electric cable of the drive motor according to the present invention. The method includes a plurality of steps, one step 302 of which includes inserting the sealing member 112 over a terminal end 204 of the electrical cable 114. The sealing member 112 includes the first portion 106 covering the jacket 108 of the electrical cable 114 and the second portion 104 having a plurality of outlets through which a plurality of conductors 102 of the electrical cable 114 pass. A step 304 includes applying heat to the sealing member 112 to shrink and seal all gaps between the sealing member 112 and the electrical cable 114. The method is characterized by a step 306 comprising inserting the element between the first portion 106 of the sealing member 112 and the sheath 108 of the electrical cable 114 prior to application of the heat. A step 308 includes removing the element after the heat shrinking process is completed. Step 306 occurs before step 306, and step 308 is performed after step 304.According to an embodiment of the present invention, the sealing member 112 prevents water ingress without losing the breathability of the drive motor. The sealing assembly 100 according to the present invention ensures that moisture is not trapped inside the driving motor at the time of manufacture, that pressure does not build up inside the driving motor with temperature rise during operation, and the air tightness test for the motor in the assembly line is very easy. Breathability of the drive motor is also maintained.It is to be understood that the embodiments described in the above description are for illustrative purposes only and do not limit the scope of this invention. Many such embodiments and other modifications and changes to the embodiment described in the specification are conceivable. The scope of the invention is limited only by the scope of the claims.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 2927558

[0005]

Claims

A sealing assembly (100) for an electric cable (114) of a drive motor, the electric cable (114) comprising a plurality of conductors (102) having respective insulation and all covered by a jacket (108), the plurality of conductors (102) being partially exposed from the insulation and the jacket for connection, the sealing assembly (100) comprising: a sealing member (112) comprising a first portion (106) having an inlet and a second portion (104) having a plurality of outlets, wherein the sealing member (112) is slidably inserted over the electric cable (108) through the first portion (106) such that the first portion (106) covers the jacket (108) of the electric cable (108) and the plurality of conductors (102) pass through the plurality of outlets of the second portion (104), the sealing member (112) is made of heat shrink tubing which shrinks and seals each gap therein upon application of heat, the first portion (106) and the second portion (104), characterized in that at least one air flow path (110) is formed between the first portion (106) of the sealing member (112) and the jacket (108) of the electrical cable (114).The sealing assembly (100) of claim 1, wherein the at least one airflow path (110) extends along the first portion (106) of the sealing member (112) and communicates with the air gap within the electrical cable (114).The sealing assembly (100) of claim 1, wherein prior to application of heat, an adhesive material is filled between the sealing member (112) and the electrical cable (114).The sealing assembly (100) of claim 1, wherein the at least one airflow path is formed in a straight line or curved line.The sealing assembly (100) of claim 1, wherein the at least one airflow path (110) is formed by inserting a member between the first portion (106) and the jacket (108) of the electrical cable (114) prior to application of heat and removing the member after application of heat.An electric cable (114) of a drive motor, the electric cable (114) comprising a plurality of conductors (102) having respective insulation and all covered by a jacket (108), the plurality of conductors (102) being partially exposed from the insulation and the jacket (108) for connection, the electric cable (114) comprising: a sealing member (112) having a first portion (106) with an inlet and a second portion (104) with a plurality of outlets, the sealing member (112) being slidably inserted over the electric cable (114) through the first portion (106) such that the first portion (106) covers the jacket (108) of the electric cable (114) and the partially exposed plurality of conductors (102) pass through the plurality of outlets of the second portion (104), the sealing member (112) is made of heat shrink tubing which shrinks the first portion (106) and the second portion (104) upon application of heat and seals any gap therein, characterised in that at least one air flow path (110) is formed between the first portion (106) of the sealing member (112) and a jacket (108) of the electrical cable (114).The electrical cable (114) of claim 6, wherein the at least one airflow path (110) is formed in a straight line or curved line, and wherein the at least one airflow path (110) is in communication with the air gap within the electrical cable (114).The electrical cable (114) of claim 6, wherein prior to application of heat, an adhesive material is filled between the sealing member (112) and the electrical cable (114).The electrical cable (114) of claim 6, wherein the at least one airflow path (110) is formed by inserting a member between the first portion (106) of the sealing member (112) and the electrical cable (114) prior to application of heat and removing the member after application of heat.A method of sealing an exposed end of an electrical cable (114) of a drive motor, the method comprising the steps of: inserting a sealing member (112) over a terminal end (204) of the electrical cable (114), the sealing member (112) comprising a first portion (106) covering the jacket (108) of the electrical cable (114) and a second portion (104) having a plurality of outlets through which a plurality of conductors (102) of the electrical cable (114) pass; applying heat to the sealing member (112) to shrink and seal all gaps therein; characterised by inserting a member between the first portion (106) of the sealing member (112) and the jacket (108) of the electrical cable (114) prior to application of the heat; and removing the member after completion of the heat shrinking process.

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