Description

STARTERHAVINGA STOPPING NOISE PREVENTABLE

STRUCTURE

[1] TECHNICAL HELD

[2] The present invention relates to a starter having a stopping noise preventable structure, and more specifically to a starter having a stopping noise preventable structure, in which the segment of commutator and the structure of the brush assembly in contact with the segment are improved so as to lower vibration sound due to friction.

[3] BACKGROUND ART

[4] In general, a starter for automobiles comprises, as shown in Fig. 1, a housing 10 having a front bracket and a rear bracket on both sides, a shaft 41 arranged inside of the housing, an armature assembly 40 mounted on the outer circumference of the shaft 41, a stator 20 that is arranged around the armature assembly 40 at a predetermined interval and which has magnets fixed on the inner circumference of the housing 10, a brush assembly 30 for supplying the electricity from battery to the armature assembly 40, an overrunning clutch 60 connected to one end of the shaft 41, a pinion 50 mounted on the overrunning clutch 60, a magnet switch assembly 80 fastened and fixed to the front bracket on one side of the outer circumference of the housing, and a lever 70 for manipulating the overrunning clutch 60 by a pop-up plunger of the magnet switch assembly 80.

[5] In such a starter, the pinion 50 can be in mesh with the ring gear (not shown) of the engine by the magnet switch assembly. In this condition if the driver turns on the key switch to start engine, the starter is operated and the pinion 50 comes into mesh with the ring gear to rotate it so that engine is started to be operated.

[6] And when engine is started and operated normally, from that moment on the rotational speed of ring gear becomes faster than the pinion, so the rotatory force is transmitted to the rotary axis of the starter in reverse through the pinion. By the rotatory force transmitted in reverse from the ring gear like above, the pinion is retreated to shunt the overrunning clutch 60 through the lever 70 to cut off battery power supply.

[7] At this time, after the armature assembly 40 mounted on the shaft rotates the shaft to supply starting power to engine, it rotates further for a certain time (about 1 to 5 seconds) by its own rotational inertia before it stops. Due to such excess rotation, vibration is generated by friction between commutator 42 and brush 31.

[8] The vibration generated at this time is transmitted to the armature assembly 40, the magnet around the armature assembly and the magnet holder 42. By such vibration, a

noise is generated until the armature assembly stops completely, and this is called a stopping noise.

[9] Meanwhile, conventional art proposed for the purpose of reducing such a stopping noise includes the following.

[10] As an example, Korea Patent Application No. 2002-29876 (Stopping noise reduction circuit for a starter) discloses a means of solution by use of a circuit in which current flowing in P coil and H coil inside the solenoid is made to flow to earth as quickly as possible. This art is just an effort to reduce the time in which a noise is generated but cannot prevent noise generation at the source.

[11] Korea Patent Application No. 2004-64558 (Noise prevention device for a starter) discloses an art in which a buffer member is inserted between magnets inside the housing. But this art also is to cut off transmission of vibration already generated and is not a structure of preventing a stopping noise at the source.

[12] DETAILED DESCRIPTION OF THE INVENTION

[ 13] (PROBLEM TO BE SOLVED BY THE INVENTION)

[14] Therefore, the major object of the present invention is to provide a starter having a stopping noise preventable structure in which the structure of the brush and brush assembly that are in contact with the commutator rotating by the excess rotatory force of the armature assembly is changed so as to induce vibration to occur irregularly, so that the noise can be lowered to a vibration sound so low that it cannot be heard, hidden by engine noise.

[15] (TECHNICAL SOLUTION)

[16] To achieve the above objects, there is provided a starter comprising a housing having a front bracket and a rear bracket, an armature assembly having a commutator mounted on a shaft inside of the housing, a stator having magnets fixed on the inner circumference of the housing around the armature assembly, a brush assembly for supplying power by contacting the commutator of the armature assembly, an overrunning clutch mounted on the front end of the shaft, a pinion mounted on the overrunning clutch, a magnet switch assembly assembled to the front bracket on one side of the outer circumferential surface of the housing, and a lever for manipulating the overrunning clutch by a pop-up plunger of the magnet switch assembly, the starter having a stopping noise preventable structure characterized in that: the brush assembly has at least one of the brush, brush spring and brush holder provided with a random vibration inducing means to induce random vibration.

[17] Preferably, the random vibration inducing means consists of a plurality of brushes of the brush assembly having contact portions with different shapes.

[18] Preferably, the random vibration inducing means consists of a plurality of brushes of the brush assembly having contact widths W with different sizes.

[19] Preferably, wherein the random vibration inducing means consists of a plurality of brushes of the brush assembly having contact surfaces with different surface roughnesses. [20] Preferably, the random vibration inducing means consists of a plurality of brushes of the brush assembly made of different materials. [21] Preferably, the random vibration inducing means consists of a plurality of brushes of the brush assembly having a central portion and an exterior portion surrounding the central portion, wherein the central portion and the exterior portion are made of different materials from each other. [22] Preferably, the random vibration inducing means consists of a plurality of brushes of the brush assembly supported by brush springs with mutual elastic forces. [23] Preferably, wherein the random vibration inducing means consists of a plurality of brushes of the brush assembly supported by brush holders 33 made of different materials. [24] Preferably, the random vibration inducing means consists of a plurality of brushes of the brush assembly supported by brush holders with different thicknesses t. [25] (ADVANTAGEOUS EFFECTS)

[26] According to the present invention, because the segments of the commutator rotating by the rotational inertia of excess rotatory force of the armature assembly rotate in contact with the irregular friction inducing means of the brush assembly, vibration due to friction occurs irregularly.

[27] BRIEF DESCRIPTION OF THE DRAWINGS

[28] These and other features, aspects, and advantages of preferred embodiments of the present invention will be more fully described in the following detailed description, taken in conjunction with the accompanying drawings. In the drawings: [29] Fig. 1 is a sectional view showing the configuration of a common starter;

[30] Fig. 2 is a perspective view of a brush assembly and commutator illustrated in Fig. 1'

[31] Fig. 3 is a front view showing the assembled condition of the brush assembly and commutator shown in Fig. 2; [32] Fig. 4 is a front view showing an example of brush according to the first embodiment of the present invention; [33] Fig. 5 is a perspective view showing another example of brush according to the first embodiment of the present invention; [34] Fig. 6 is a perspective view showing a further example of brush according to the first embodiment of the present invention; [35] Fig. 7 is a front view showing the mounted condition of a brush spring according to the second embodiment of the present invention; [36] Fig. 8 is a sectional view of a brush holder according to the third embodiment of the

present invention;

[37] Fig. 9 is a reference drawing showing the condition of the noise generated from the commutator according to the conventional art and the application of example of the present invention.

[38] BEST MODE FOR CARRYING OUT THE INVENTION

[39] Below will be described in detail the configuration and action of a starter having a stopping noise preventable structure according to the embodiments of the present invention with reference to the accompanying drawings.

[40] First, the configuration of a starter according to the present invention is roughly similar to the description given in Fig. 1. That is, the starter for automobiles comprises a housing 10 having a front bracket and a rear bracket on both sides, a shaft 41 arranged inside of the housing, an armature assembly 40 mounted on the outer circumference of the shaft 41, a stator 20 that is arranged around the armature assembly 40 at a predetermined interval and which has magnets fixed on the inner circumference of the housing 10, a brush assembly 30 for supplying the electricity from battery to the armature assembly 40, an overrunning clutch 60 connected to one end of the shaft 41, a pinion 50 mounted on the overrunning clutch 60, a magnet switch assembly 80 fastened and fixed to the front bracket on one side of the outer circumference of the housing, and a lever 70 for manipulating the overrunning clutch 60 by a pop-up plunger of the magnet switch assembly 80.

[41] The brush assembly 30 comprises, as shown in Fig. 2, a plate 34, a brush holder 33 fixed on the inside of the plate 34, a brush 31 assembled in the brush holder 33, and a brush spring that presses the rear of the brush 33 so that the front end of the brush comes into contact with the segment 42a of the commutator 42. The brush holder 33 is covered with a cover 43 for protection. Each of brushes 31 is connected to a cable 35 for power supply.

[42] At this time, the present invention for prevention of stopping noise is described by dividing into the first embodiment in which the aforementioned brush 31 is improved, the second embodiment in which the aforementioned brush spring 32 is improved, and the third embodiment in which the aforementioned brush holder 33 is improved.

[43] First Embodiment

[44] First, 4 brushes 31 are shown in Fig. 4. The first embodiment illustrates a structure of these brushes in which the cylinder plane of the commutator 42, that is, the contact portion 31a that is in contact with each segment 42a, is formed differently from each other.

[45] For example, whereas the contact surface 3 Ib of the brush 31 at the left top end in

Fig. 4 is formed in a concave shape so that the contact area with the surface of the cylindrical commutator 42 is large, the contact surface 31a of the brush 31 at the right

top end in Fig. 4 is formed in a convex shape or straight line shape so that the contact area with the surface of the cylindrical commutator 42 is small.

[46] In another embodiment, the surface roughness of the contact surface 3 Ib of the contact portion can be formed differently so as to induce irregular vibration.

[47] If formed like this, the sound wave according to the vibration becomes small due to irregular vibration even if vibration is generated by each of segments 42a.

[48] Also, as shown in Fig. 5, the widths W of brushes 31 are formed differently so as to induce vibration to be irregular.

[49] For example, all the widths W of 4 brushes may be formed differently, or the widths of the brushes facing each other with the commutator in between may be formed the same while the widths of the other adjacent brushes are formed differently.

[50] Meanwhile, brushes 31 of the present invention may be made of different materials so as to induce irregular vibration. For example, most brushes are made of copper in consideration of the flow of current, but by use of mutually adjacent brushes that are made of materials other than copper or made of copper alloy, it is possible to induce irregular vibration.

[51] On the other hand, since the irregular vibration inducing means 100 is to improve the sliding motion characteristic due to friction when the brush goes over each segment, the material of the brush unit itself may be made up of double layer of two materials. That is, the materials of the inside layer and outside layer of the brush can be different.

[52] For example, the central portion 3 Ic of the inside of brushes 31 can be made of material with electrical characteristics identical or similar to the existing brush, and the exterior portion 3 Id of the outside can be made of material with good sliding or lubricating characteristics.

[53] By forming like this, vibration can be reduced by lowering resistance at the time of sliding motion while maintaining the existing electrical characteristics.

[54] Second Embodiment

[55] As shown in Fig. 7, one brush spring 32 is provided for each of 4 brushes 31. In this embodiment, by use of brush springs 32 with the diameter d or elastic modulus different from each other (springs of different materials), the vibration generated when the front end of the brush comes into contact with the surface of commutator is induced irregularly due to the difference between diameters or elastic moduli.

[56] Third Embodiment

[57] And as shown in Fig. 8, it is possible to induce irregular vibration due to difference in thickness by forming the thickness t of the brush holder 33 differently from each other.

[58] For example, all the thicknesses t of 4 brush holders 33 may be made different, or the thickness of the brush holders 33 facing each other with the commutator 42 in between

may be formed with the same thicknesses while the thicknesses of the other adjacent brush holders 33 are formed with different thicknesses. [59] Not only that, if the aforementioned brush holders 33 are made of different materials such as steel and plastic, it is possible to induce irregular vibration due to different friction characteristics of material. [60] At this time, because the present invention is provided with an irregular vibration inducing means 100 that is formed in at least one of the brush 31 of the brush assembly

30, the brush spring 32 and the brush holder 33, irregular vibration is generated without fail.

[61] INDUSTRIAL APPLICABILITY

[62] According to the present invention, because the segments of the commutator rotating by the rotational inertia of excess rotatory force of the armature assembly rotate in contact with the irregular friction inducing means of the brush assembly, vibration due to friction occurs irregularly. [63] Although the present invention has been described in connection with the exemplary embodiments illustrated in the drawings, it is only illustrative. It will be understood by those skilled in the art that various modifications and equivalents can be made to the present invention. Therefore, the true technical scope of the present invention should be defined by the appended claims.