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 an irregular friction inducing means is formed in the segment of commutator rotating by the excess rotatory force of the armature assembly so as to induce vibration due to friction to occur irregularly, so that the noise can be lowered to a vibration sound of a level 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 commutator that the brush contacts is provided with a plurality of segments arranged circum- ferentially, and the circumferential surface of each segment is provided with a random friction inducing means consisting of any one of a randomly processed portion, a random radius portion and a random gap portion.

[17] Preferably, the randomly processed portion of the random friction inducing means is a plurality of protrusions formed randomly on the surfaces of at least one of the cir-

cumferential segments provided on the commutator. [18] Preferably, the plurality of protrusions are formed to be partly protruded by a caulking method and are formed randomly on the surface of at least one segment of the circumferentially arranged segments. [19] Preferably, the randomly processed portion of the random friction inducing means is arranged randomly on the surface of at least one of the circumferential segments provided on the commutator. [20] Preferably, the randomly processed portion of the random friction inducing means is an inclined plane formed in repetitive inclinations on the surfaces of the circumferential segments provided on the commutator. [21] Preferably, the random radius portion of the random friction inducing means consists of circumferential segments provided on the commutator so as to have different radiuses R. [22] Preferably, the random radius portion of the random friction inducing means consists of circumferential segments provided on the commutator so as to have an elliptical shape as a whole as the diameter d2 gradually increases and then decreases gradually to diameter dl. [23] Preferably, the random gap portion of the random friction inducing means consists of circumferential segments provided on the commutator so as to have different widths

W. [24] Preferably, the random gap portion of the random friction inducing means consists of the circumferential segments provided on the commutator so as to have different gaps

G between segments.

[25] (ADVANTAGEOUS EFFECTS)

[26] According to the present invention, because the segment of the commutator rotating by the excess rotatory force of the armature assembly is provided with a means of inducing irregular friction, vibration due to friction occurs irregularly. [27] Therefore, the level of noise generated due irregular vibration is very weak compared with the existing stopping noise, and the sound wave is a vibration sound so low that it cannot be heard as it is hidden by engine noise, so the consumer can hardly notice the noise, and thereby a starter that can prevent the stopping noise can be provided. [28] BRIEF DESCRIPTION OF THE DRAWINGS

[29] 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: [30] Fig. 1 is a sectional view showing the configuration of a conventional starter;

[31] Fig. 2 is a perspective view of the brush assembly and commutator illustrated in Fig.

1;

[32] Fig. 3 is a perspective view of a commutator according to the first embodiment of the present invention;

[33] Fig. 4 is a development view showing the array of segments according to the first embodiment of the present invention;

[34] Fig. 5 is a perspective view of a commutator in another processing condition according to the first embodiment of the present invention;

[35] Fig. 6 is a perspective view of a commutator having a knurling portion according to the first embodiment of the present invention;

[36] Fig. 7 is a perspective view and front view of a commutator having an inclined portion according to the first embodiment of the present invention;

[37] Fig. 8 is a perspective view and front view of a commutator having an irregular radius portion according the second embodiment of the present invention;

[38] Fig. 9 is a front view of an elliptical commutator according to the second embodiment of the present invention;

[39] Fig. 10 is a perspective view and front view of a commutator having irregular gap portions according to the third embodiment of the present invention;

[40] Fig. 11 is a perspective view and front view of a commutator having irregular gap portions according to the third embodiment of the present invention; and

[41] Fig. 12 is a reference drawing showing the condition of noise generated from a commutator according to application of examples of conventional art and the present invention.

[42] BEST MODE FOR CARRYING OUT THE INVENTION

[43] 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.

[44] 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.

[45] 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.

[46] The conventional commutator 42 is made in a cylindrical form as shown in Fig. 2, and a plurality of segments 42a are arranged on the surface of the cylindrical form. In general, the segments arranged at a predetermined gap G have a predetermined width W, and insulation of commutator is achieved by these segments.

[47] In the starter of the present invention, as an irregular friction inducing means 100 for preventing stopping noise, the first embodiment discloses an irregular processed portion 110, the second embodiment discloses an irregular radius portion 120, and the third embodiment discloses an irregular gap portion 130, and these means can be adopted selectively or in combination.

[48] First Embodiment

[49] According to the first embodiment, as shown in Figs. 3 to 7, as an irregular friction inducing means 100 for prevention of stopping noise, an irregular processed portion

110 formed on the surface of the segments 42a of the commutator mounted in the housing of starter is illustrated.

[50] First, in an example of this embodiment shown in Fig. 3, a plurality of protuberances

111 formed on the surface of the segment 42a are illustrated as a means of inducing irregular friction.

[51] At this time, it is preferable to process the protuberances 111 with the well-known caulking method, and they are arrayed irregularly as shown in Fig. 4.

[52] Also, in other example of this embodiment shown in Fig. 5, protuberances 111 are formed lengthily along the width direction of the segment. The protuberances 111 are arrayed on one segment 42a lengthwise of the segment with many of them in parallel, and the segments 42a can be configured in such a way that each segment is provided with a different number of protuberances.

[53] In another example of this embodiment shown in Fig. 6, a knurling portion 112 formed on the surface of the segment 42a is illustrated as a means of inducing irregular friction.

[54] This knurling portion 112 is to make surface roughness partially different on one segment 42a; in other words, it is possible to make the roughness extent of the surface partially different. It is also possible to make the surface roughness of each segment 42a different or the area of the knurling portion different.

[55] Another example of this embodiment shown in Fig. 7 illustrates an inclined plane

113 as a means of inducing irregular friction, which is formed in inclination by

lowering the height of some of segments 42a.

[56] This inclined plane 113 is processed with one side lower and the other side higher than the adjacent segment 42a, and it is also possible to form the rear side lower or the front side lower with respect to the rotation direction of the rotating commutator 42.

[57] Second Embodiment

[58] The second embodiment illustrates, as shown in Figs. 8 and 9, an irregular radius portion 12, in which the dimensions of segments 42a of the commutator 42 are irregularly formed, as a means of inducing irregular friction for prevention of stopping noise.

[59] An example of this embodiment shown in Fig. 8 illustrates that radiuses R from the center point of adjacent segments 42a are made different. Here, the array of different radiuses can be achieved by applying Fig. 4.

[60] Namely, as shown in Fig. 8, the dimensions of radius R from the center point, Rl,

R2, R3, etc. are made in various sizes. That is, the radiuses R between adjacent segments are made different, and it is preferable to array segments having different radiuses irregularly.

[61] Another example of this embodiment shown in Fig. 9 illustrates a structure in which the diameters d2 of all segments 42a increase and then gradually decrease to diameters dl, so that they have an elliptical shape as a whole.

[62] Third Embodiment

[63] The third embodiment illustrates, as shown in Figs. 10 and 11, an irregular gap portion 130, in which the circumferential dimensions of the segments 42a of the commutator 42 are formed irregularly, as a means of inducing irregular friction.

[64] An example of this embodiment shown in Fig. 10 illustrates a commutator 42 in which the width dimensions Wl and W2 of segments 42a are formed irregularly.

[65] Namely, the widths Wl and W2 of segments 42a are made in two (or more) different dimensions and the segments with different widths are arrayed in an irregular sequence.

[66] Another example of this embodiment shown in Fig. 11 illustrates a commutator 42 in which the gaps Gl and G2 between segments 42a are formed irregularly.

[67] Namely, the gaps Gl and G2 between segments are made in two (or more) different dimensions and the gaps between different segments are formed irregularly.

[68] The action of the starter of the present invention that is configured like the above embodiments will be described below.

[69] When the driver turns on the key switch to start car engine, power is supplied from battery and the armature assembly 40 is rotated like a common starter and engine is started by its rotatory force.

[70] When the engine is started and inertia of the armature assembly 40, that is, excess

rotatory force exists, friction by the excess rotatory force continues, because the brush 31 of the brush assembly 30 is still in contact with the commutator 42.

[71] At this time, in the present invention, since the commutator 42 is provided with an irregular friction inducing means 100 that includes any one of the various irregular processed portions 110, the irregular radius portion 120 and the irregular gap portion 130, vibration occurs irregularly.

[72] Therefore, the noise generated due to such irregular vibration is weaker than the existing stopping noise, so the operator can hardly notice it because it is hidden by engine noise, and it disappears as soon as rotational inertia becomes weak.

[73] Such a phenomenon can be confirmed through Fig. 12 in which the conventional noise diagram and the noise diagram of the present invention are compared.

[74] INDUSTRIAL APPLICABILITY

[75] According to the present invention, because the segment of the commutator rotating by the excess rotatory force of the armature assembly is provided with a means of inducing irregular friction, vibration due to friction occurs irregularly.

[76] Therefore, the level of noise generated due irregular vibration is very weak compared with the existing stopping noise, and the sound wave is a vibration sound so low that it cannot be heard as it is hidden by engine noise, so the consumer can hardly notice the noise, and thereby a starter that can prevent the stopping noise can be provided.

[77] 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.