WO2008029988A1

WO2008029988A1 - Wiper arm assembly

Info

Publication number: WO2008029988A1
Application number: PCT/KR2007/003482
Authority: WO
Inventors: Wi-Yeong Park
Original assignee: Dongyang Mechatronics Corp.
Priority date: 2006-09-06
Filing date: 2007-07-19
Publication date: 2008-03-13
Also published as: KR100800581B1

Abstract

The wiper arm assembly includes: an arm head having a support shaft; a retainer including combined with the arm head; and a rotation-preventing unit restricting rotation of the retainer so that the retainer is not rotated past the predetermined angle when the retainer is rotated around the support shaft due to an external force. The retainer includes an accommodation hole having an opened portion so that the support shaft can be attached to or detached from the retainer through the opened portion in a predetermined position, and the support shaft has a first position in which the support shaft cannot be separated from the accommodation hole and a second position in which the support shaft can be separated from the accommodation hole, while the support shaft is rotated within the rotation angle, due to a different cross-sections of the support shaft perpendicular to its lengthwise direction.

Description

WIPER ARM ASSEMBLY

Technical Field

[1] The present invention relates to a rear wiper arm assembly of a vehicle, and more particularly, to a wiper arm assembly having an improved structure in which the rear wiper arm assembly is prevented from being in a lockback state by an unintended external force. Background Art

[2] Conventionally, a rear wiper needs to be installed on a rear glass of a vehicle according to an inclination angle of the rear glass of a vehicle. In most cases, a rear wiper is not installed on a rear glass of a so-called sedan notch back type vehicle. However, a rear wiper is necessarily installed on a rear glass of a hatch back type vehicle, such as a sports utility vehicle (SUV). The installation of the rear wiper on the rear glass of a vehicle is done because a negative pressure is generated on the rear glass while driving and dust easily collects on the rear glass according to the type of vehicle.

[3] An example of a vehicle in which a rear wiper is installed on a rear glass of the vehicle is illustrated in FIG. 1. Conventionally, the rear wiper of a rear glass is an assembly comprised of a plurality of components and hence, hereinafter referred to as a wiper arm assembly 1.

[4] Referring to FIGS. 1 through 4, the wiper arm assembly 1 includes three elements. In detail, the wiper arm assembly 1 includes an arm head 2, a retainer 3, and a blade 4. The arm head 2 is fixed on a pivot shaft 6 that is installed on a body and is rotated together with the pivot shaft 6 due to rotations of the pivot shaft 6. The retainer 3 is combined with one end of the arm head 2 and transmits a rotation force of the arm head 2 to the blade 4. The blade 4 slides in contact with a glass of the vehicle and wipes and removes foreign substances stuck on the glass of the vehicle.

[5] In the wiper arm assembly 1 having the above structure, a tension spring 5 is usually installed in the structure for connecting the retainer 3 and the arm head 2 so that the blade 4 can apply pressure to the glass of the vehicle. One end of the tension spring 5 is attached to the retainer 3 and the other end thereof is attached to the arm head 2. Thus, when the retainer 3 is rotated by the elastic force of the tension spring 5 in a direction that is slightly distant from the glass of the vehicle, a position in which action directions of an elastic force of the tension spring 5 are opposite to each other according to the range of the rotation angle of the retainer 3, that is, a toggle line indicated by TL of FIG. 4, is reached. An event in which the action directions of the elastic force of the tension spring 5 are changed is referred to as a toggle action. If the retainer 3 is rotated over the toggle line TL by the toggle action, the blade 4 is in a state where the blade 4 is not applying pressure on the glass of the vehicle and is spaced apart from the glass by a predetermined gap, that is, in a lockback state as illustrated in FIGS. 2 and 4.

[6] Conventionally, the lockback state has been used for disassembling of the wiper arm assembly 1 so as to perform maintenance or repair of the wiper arm assembly 1.

[7] However, as vehicles are being washed more frequently with automatic car washing machines of car washes as opposed to being washed by hand, a brush of the automatic car washing machine rotates and wipes the outside of the vehicle. In this procedure, a portion of the brush is stuck with the wiper arm assembly 1 when the brush rotates and as such, the wiper arm assembly 1 reaches an unintended lockback state. Due to this, the wiper arm assembly 1 may be broken or damaged.

[8] In addition, since the appearance of the vehicle plays a big role for customers these days, the tendency for manufacturing the wiper arm assembly 1 using plastics has increased. Thus, cross-sections of the retainer 3 are formed of plastics that are generally ' D '-shaped and an opened cross-section thereof is directed toward the glass of the vehicle. Due to the cross-sections, if a strong flow of air is applied to the glass of the vehicle during a drying operation of an automatic car washing machine, as indicated by arrows of FIG. 1, the air reflected from the glass of the vehicle enters the ' D '-shaped opened cross-section of the retainer 3 and forcibly rotates the retainer 3 and thus, the lockback state as illustrated in FIG. 2 may occur. Also, the wiper arm assembly 1 may be damaged by colliding with a sensor member of the automatic car washing machine that moves along an outer contour of the vehicle during drying of the vehicle.

Disclosure of Invention Technical Problem

[9] Accordingly, a function of preventing a lockback state of the wiper arm assembly 1 mounted on the vehicle is required. In addition, easy assembling and disassembling of the retainer 3 and the arm head 2 so as to effectively reduce assembling and production costs of the wiper arm assembly 1 is highly required. Advantageous Effects

[10] As described above, in the wiper arm assembly according to the present invention, the rotation-preventing unit constituted by combining the lockback-pre venting jaw and the suspending portion prevents the wiper arm assembly from being in a lockback state due to an unintended external force and prevents the wiper arm assembly from being damaged due to the lockback state. As such, by properly combining the support shaft and the accommodation hole in a non-lockback state, i.e., in the first position, the support shaft cannot be separated from the accommodation hole and in the second position, the support shaft can be separated from the accommodation hole so that maintenance or repair of the wiper arm assembly can be easily performed and manufacturing costs can be reduced as compared to a structure in which the support shaft cannot be separated from the accommodation hole. Description of Drawings

[11] The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:

[12] FIG. 1 is a schematic view of a vehicle in which a conventional wiper arm assembly is installed;

[13] FIG. 2 illustrates a state where the wiper arm assembly illustrated in FIG. 1 is in a lockback state;

[14] FIG. 3 illustrates a portion of a schematic lengthwise cross-sectional view in which the conventional wiper arm assembly;

[15] FIG. 4 illustrates the state where the conventional wiper arm assembly illustrated in

FIG. 3 is in a lockback state;

[16] FIG. 5 is a schematic partial cross-sectional view of a wiper arm assembly according to an embodiment of the present invention;

[17] FIG. 6 is an enlarged view of portion 'A' of FIG. 5, according to an embodiment of the present invention;

[18] FIG. 7 illustrates a function of a rotation-preventing unit of the wiper arm assembly illustrated in FIG. 6, according to an embodiment of the present invention;

[19] FIG. 8 illustrates a state of the wiper arm assembly of FIG. 5 where a tension spring is removed, according to an embodiment of the present invention;

[20] FIG. 9 illustrates the state of FIG. 8 where a retainer is rotated and is attached to a lockback-pre venting jaw, according to an embodiment of the present invention; and

[21] FIG. 10 illustrates an operation of separating the retainer from an arm head, in the state of FIG. 9, according to an embodiment of the present invention. Best Mode

[22] The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown.

[23] FIG. 5 is a schematic partial cross-sectional view of a wiper arm assembly 10 according to an embodiment of the present invention, FIG. 6 is an enlarged view of portion 'A' of FIG. 5, and FIG. 7 illustrates a function of a rotation-preventing unit of the wiper arm assembly illustrated in FIG. 6, according to embodiments of the present invention.

[24] Referring to FIGS. 5 through 7, the wiper arm assembly 10 includes an arm head 20, a retainer 30, a blade 40, and a tension spring 50.

[25] One end of the arm head 20 is fixed on a pivot shaft 11 that is fixed on a vehicle using a cap nut, for example. The pivot shaft 11 is connected to a link structure (not shown) connected to a motor and is rotated by a driving force of the motor. The arm head 20 rotates around a portion of the pivot shaft 11 at a predetermined angle as the pivot shaft 11 is rotated. The arm head 20 includes a support shaft 22 and a lockback- preventing jaw 24.

[26] The support shaft 22 is disposed on the other side of the portion of the arm head 20 fixed on the pivot shaft 11. The support shaft 22 is formed integrally with the arm head 20. The support shaft 22 is disposed in a direction perpendicular to the lengthwise direction of the arm head 20. Cross-sections of the support shaft 22 perpendicular to the lengthwise direction of the support shaft 22 are 'D'-shaped, and a curve portion 223 is a portion of a circle. An interference evasion groove 226 is formed in the curve portion 223. The interference evasion groove 226 is formed concavely in the circumference of the curve portion 223. A first diameter dl of the curve portion 223 of the support shaft 22 corresponds to a dimension of the linear portion 221 in a lengthwise direction of the linear portion 221 and is greater than a second diameter d2 of the support shaft 22, and the second diameter d2 of the support shaft 22 corresponds to a dimension of the linear portion 221 in a direction perpendicular to the lengthwise direction of the linear portion 221. The support shaft 22 has a first position such that the support shaft 22 cannot be separated from the retainer 30 and a second position such that the support shaft 22 can be separated from the retainer 30 while the support shaft 22 rotates within a rotation angle. The first and second positions of the support shaft 22 are reached relative to the retainer 30 as will be described in detail when describing the retainer 30. The lockback-pre venting jaw 24 protrudes from the arm head 20.

[27] One end of the retainer 30 is combined with the support shaft 22 so that the retainer

30 can rotate around the support shaft 22. The other end of the retainer 30 is combined with the blade 40 for wiping the glass of the vehicle. The retainer 30 includes a suspending portion 36 and an accommodation hole 32. The suspending portion 36 is prevented from rotating by the lockback-pre venting jaw 24 disposed on the arm head 20. The suspending portion 36 and the lockback-pre venting jaw 24 prevent the rotation of the retainer 30 from reaching a lockback state. Such a function can be implemented by properly combining the position of the lockback-pre venting jaw 24 and the suspending portion 36. The accommodation hole 32 is disposed in the retainer 30 in order to accommodate the support shaft 22 of the arm head 20 that can be attached to or detached from the retainer 30. The accommodation hole 32 of the retainer 30 includes an accommodation portion 33 and an opened portion 34. The accommodation portion 33 of the accommodation hole 32 accommodates the support shaft 22, contacts the support shaft 22 and can rotate around the support shaft 22. An inner circumference of the accommodation portion 33 contacts the curve portion 223 of the support shaft 22. The opened portion 34 of the accommodation hole 32 extends from the accommodation portion 33 and is opened toward the outside. The opened portion 34 includes wall surfaces 341 spaced apart from one another in parallel by a distance that is less than the first diameter dl of the support shaft 22 and is greater than the second diameter d2 of the support shaft 22. The support shaft 22 may be separated from or attached to the accommodation portion 33 of the accommodation hole 32 through a space between the wall surfaces 341. The first position is a position in which, since the first diameter dl of the support shaft 22 does not allow the opened portion 34 of the retainer 30 to separate while the retainer 30 is rotated around the support shaft 22, the support shaft 22 cannot be separated from the accommodation hole 32. The second position is a position in which, since the second diameter d2 of the support shaft 22 allows the opened portion 34 of the retainer 30 to pass while the accommodation hole 32 of the retainer 30 is rotated around the support shaft 22, the support shaft 22 can be separated from the accommodation hole 32 of the retainer 30. The interference evasion groove 226 disposed in the support shaft 22 makes space between the support shaft 22 and the wall surfaces 341 so that, when the support shaft 22 is separated from the accommodation hole 32 of the retainer 30 in the second position, the support shaft 22 avoids interference with the wall surfaces 341 of the opened portion 34.

[28] The blade 40 is combined with the other end of the retainer 30 and is installed to rotate with the retainer 30. The blade 40 includes an elastic material such as rubber, directly contacts the glass of the vehicle, and wipes and removes foreign substances stuck on the surface of the glass. The blade 40 presses against the glass of the vehicle due to a tension spring 50 as described later.

[29] One end of the tension spring 50 is attached to the arm head 20 so as to combine the arm head 20 and the retainer 30, and the other end of the tension spring 50 is attached to the retainer 30. The case where an elastic force of the tension spring for restoring the retainer 30 to its initial position is not able to be applied is referred to as a lockback state and thus, the retainer 30 is distant from the glass of the vehicle as per when the retainer 30 is rotated over a position TL as illustrated in FIG. 7. In the present invention, the lockback state is prevented by combining the lockback-preventing jaw 24 and the suspending portion 36.

[30] An operation of the wiper arm assembly 10 having the above structure will now be described in detail.

[31] Firstly, referring to FIG. 7, in the state where the wiper arm assembly 10 is installed on the glass of the vehicle, the blade 40 presses against the glass of the vehicle due to a function of the tension spring 50. However, when high-pressure air is sprayed onto the glass of the vehicle during a drying operation of an automatic car washing machine, for example, the retainer 30 rotates around the support shaft 22 due to the high-pressure air and thus, the blade 40 connected to the retainer 30 moves away from the glass of the vehicle. If the retainer 30 rotates around the support shaft 22 in this way, the suspending portion 36 rotates around the support shaft 22 and combines with the lockback-preventing jaw 24 disposed in the arm head 20. The lockback-preventing jaw 24 combines with the suspending portion 36 so that rotation of the retainer 30 does not occur any more. Since an elastic force for restoring the tension spring 50 to its initial position acts on the tension spring 50 in this state, if an external force is removed, the retainer 30 is restored to its initial position due to the elastic force of the tension spring 50. That is, the state of the retainer 30 is not changed into the lockback state. Thus, since the blade 40 connected to the retainer 30 is also restored to its initial position and presses against the glass of the vehicle, the wiper arm assembly 10 is not damaged.

[32] An additional operation of the wiper arm assembly 10 according to the present invention will now be described in association with the case where the retainer 30 is disassembled from the wiper arm assembly 1.

[33] Referring to FIGS. 6 and 8 through 10, FIG. 6 illustrates an initial state in which the wiper arm assembly 10 is installed on the glass of the vehicle. When the retainer 30 is disassembled from the arm head 20 so as to perform maintenance or repair of the wiper arm assembly 10, the tension spring 50 is removed using a proper tool (not shown), as illustrated in FIG. 8. In this state, the retainer 30 cannot be separated from the arm head 20. That is, the state is a position corresponding to the first position and a portion of the support shaft 22 having the first diameter dl is attached to the opened portion 34 of the accommodation hole 32 such that the support shaft 22 cannot be separated from the accommodation hole 32. Thus, the retainer 30 is rotated in a direction that is distant from the glass of the vehicle up to a position in which the suspending portion 36 disposed on the retainer 30 is combined with the lockback-preventing jaw 24 disposed on the arm head 20, that is, the second position. In the second position, a portion of the support shaft 22 having the second diameter d2 is adjacent to the wall surfaces 341 of the opened portion 34 and allows the opened portion 34 to pass so that the support shaft 22 can be separated from the accommodation hole 32 in a separation direction X as illustrated in FIG. 10. In this procedure, the interference evasion groove 226 makes space between the wall surfaces 341 of the opened portion 34 and an outer surface of the support shaft 22 so that the support shaft 22 can more easily allow the opened portion 34 to pass.

[34] As described above, the rotation-preventing unit constituted by combining the lockback-preventing jaw 24 and the suspending portion 36 prevents the wiper arm assembly 10 from being in a lockback state due to an unintended external force and prevents the wiper arm assembly 10 from being damaged due to the lockback state. Meanwhile, as in FIG. 5, by properly combining the support shaft 22 and the accommodation hole 32, in the first position, the support shaft 22 cannot be separated from the accommodation hole 32 and in the second position, the support shaft 22 can be separated from the accommodation hole 32. Thus, maintenance or repair of the wiper arm assembly 10 can be easily performed and manufacturing costs can be reduced as compared to the structure in which the support shaft 22 cannot be separated from the accommodation hole 32.

[35] In the present embodiment, the rotation-preventing unit includes the lockback- pre venting jaw 24 protruding from the arm head 20 and the suspending portion 36 formed on the retainer 30, the suspending portion 36 combines with the lockback- preventing jaw 24 and prevents rotation of the retainer 30 into the lockback state. However, the objective of the present invention can be achieved by other elements having the same functions as those of the lockback-preventing jaw 24 and the suspending portion 36.

[36] In the present embodiment, the retainer 30 includes the accommodation hole 32 having the opened portion 34 so that the support shaft 22 can be attached to or detached from the retainer 30. The support shaft 22 can be in the first position in which the support shaft 22 cannot be separated from the accommodation hole 32 and the second position in which the support shaft 22 can be separated from the accommodation hole 32, while the support shaft 22 is rotated within the rotation angle, due to a difference in the sizes of cross-sections that are perpendicular to its lengthwise direction. Even when the sizes of the cross-sections of the support shaft 22 are the same, the objective of the present invention can be achieved when the cross-sections of the support shaft 22 have elasticity in the second position and the support shaft 22 allows the opened portion 34 to pass.

[37] In the present embodiment, cross-sections of the support shaft 22 perpendicular to its lengthwise direction are 'D'-shaped in which a portion of a circle is cut, and the first diameter dl is a dimension in the lengthwise direction of the linear portion 221 from the cross-sections of the support shaft 22 and is greater than the dimension of the opened portion 34, and the second diameter d2 is a dimension in a direction perpendicular to the lengthwise direction of the linear portion 221 and is less than the dimension of the opened portion 34. Thus, the support shaft 22 does not allow the opened portion 34 to pass and cannot be separated from the accommodation hole 32 in the first position, and the support shaft 22 does not allow the opened portion 34 to pass and can be separated from the accommodation hole 32 in the second position. However, even when the cross-sections of the support shaft 22 are not 'D'-shaped and the objective of the present invention can be achieved, the scope of the present invention is maintained.

[38] In the present embodiment, when the support shaft 22 allows the opened portion 34 to pass in the second position in the separation direction X from the accommodation hole 32, the interference evasion groove 226 of the support shaft 22 is formed to avoid interference with the wall surfaces 341 of the opened portion 34. However, the objective of the present invention can be achieved if the interference between the wall surfaces 341 of the opened portion 34 and the support shaft 22 can be avoided without the interference evasion groove 226 of the support shaft 22.

[39] As described above, in the wiper arm assembly according to the present invention, the rotation-preventing unit constituted by combining the lockback-pre venting jaw and the suspending portion prevents the wiper arm assembly from being in a lockback state due to an unintended external force and prevents the wiper arm assembly from being damaged due to the lockback state. As such, by properly combining the support shaft and the accommodation hole in a non-lockback state, i.e., in the first position, the support shaft cannot be separated from the accommodation hole and in the second position, the support shaft can be separated from the accommodation hole so that maintenance or repair of the wiper arm assembly can be easily performed and manufacturing costs can be reduced as compared to a structure in which the support shaft cannot be separated from the accommodation hole.

[40] While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by one of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. Mode for Invention

[41] According to an aspect of the present invention, there is provided a wiper arm

[42] assembly, the wiper arm assembly including: an arm head including one end fixed on a pivot shaft installed on a body and the other end having a support shaft; a retainer including one end combined with the arm head so that the retainer can rotate around the support shaft, and the other end combined with a blade for wiping a glass of a vehicle; a tension spring including one end attached to the retainer and the other end attached to the arm head, so as to connect and support the retainer and the arm head and to pull the retainer toward the glass of the vehicle within a predetermined rotation angle so that the blade presses against the glass of the vehicle; and a rotation- preventing unit restricting rotation of the retainer so that the retainer is not rotated past the rotation angle when the retainer is rotated around the support shaft in a direction in which the blade distances from the glass of the vehicle due to an external force.

[43] According to another aspect of the present invention, there is provided a wiper [44] arm assembly, the wiper arm assembly including: an arm head including one end fixed on a pivot shaft installed on a body and the other end having a support shaft; a retainer including one end combined with the arm head so that the retainer can rotate around the support shaft, and the other end combined with a blade for wiping a glass of a vehicle; and a tension spring including one end attached to the retainer and the other end attached to the arm head so as to connect and support the retainer and the arm head and to pull the retainer toward the glass of the vehicle within a predetermined rotation angle so that the blade presses against the glass of the vehicle, wherein the retainer comprises an accommodation hole having an opened portion so that the support shaft can be attached to or detached from the retainer through the opened portion in a predetermined position in which the retainer does not exceed the rotation angle, and the support shaft has a first position in which the support shaft cannot be separated from the accommodation hole and a second position in which the support shaft can be separated from the accommodation hole while the support shaft is rotated within the rotation angle, due to a difference in sizes of cross-sections of the support shaft perpendicular to its lengthwise direction.

[45] The rotation-preventing unit may include: a lockback-preventing jaw protruding from the arm head; and a suspending portion formed on the retainer, combined with the lockback-preventing jaw when the retainer rotates and preventing rotation of the retainer through the combination of the suspending portion and the lockback- preventing jaw.

[46] The retainer may include an accommodation hole having an opened portion

[47] so that the support shaft can be attached to or detached from the retainer through the opened portion, and the support shaft may be in a first position in which the support shaft cannot be separated from the accommodation hole of the retainer and in a second position in which the support shaft can be separated from the accommodation hole of the retainer while the support shaft rotates within the rotation angle due to a difference in sizes of cross-sections of the support shaft perpendicular to its lengthwise direction.

[48] The cross-sections of the support shaft perpendicular to its lengthwise direction may be 'D'-shaped in which a portion of a circle is cut, a first diameter which is a dimension in the lengthwise direction of a linear portion from the cross-sections may be greater than a dimension of the opened portion, and a second diameter which is a dimension in a direction perpendicular to the lengthwise direction of the linear portion may be less than the dimension of the opened portion so that, in the first position, the support shaft does not allow the opened portion to pass and cannot be separated from the accommodation hole, and in the second position, the support shaft allows the opened portion to pass and can be separated from the accommodation hole .

[49] An interference evasion groove may be formed in the support shaft to avoid in- terference with wall surfaces of the opened portion when the support shaft allows the opened portion to pass in a direction in which the support shaft is separated from the accommodation hole in the second position. Industrial Applicability

[50] The present invention provides a wiper arm assembly having an improved structure in which the wiper arm assembly is prevented from being in a lockback state due to an unintended external force or a blade of the wiper arm assembly is easily separated from a retainer of the wiper arm assembly when in a non-lockback state.

Claims

[1] A wiper arm assembly comprising: an arm head including one end fixed on a pivot shaft installed on a body and the other end having a support shaft; a retainer including one end combined with the arm head so that the retainer can rotate around the support shaft, and the other end combined with a blade for wiping a glass of a vehicle; a tension spring including one end attached to the retainer and the other end attached to the arm head, so as to connect and support the retainer and the arm head and to pull the retainer toward the glass of the vehicle within a predetermined rotation angle so that the blade presses against the glass of the vehicle; and a rotation-preventing unit restricting rotation of the retainer so that the retainer is not rotated past the rotation angle when the retainer is rotated around the support shaft in a direction in which the blade distances from the glass of the vehicle due to an external force.

[2] The wiper arm assembly of claim 1, wherein the rotation-preventing unit comprises: a lockback-pre venting jaw protruding from the arm head; and a suspending portion formed on the retainer, combined with the lockback- pre venting jaw when the retainer rotates and preventing rotation of the retainer through the combination of the suspending portion and the lockback-preventing jaw.

[3] The wiper arm assembly of claim 1, wherein the retainer comprises an accommodation hole having an opened portion so that the support shaft can be attached to or detached from the retainer through the opened portion, and the support shaft can be in a first position in which the support shaft cannot be separated from the accommodation hole of the retainer and in a second position in which the support shaft can be separated from the accommodation hole of the retainer while the support shaft rotates within the rotation angle due to a difference in sizes of cross-sections of the support shaft perpendicular to its lengthwise direction.

[4] The wiper arm assembly of claim 3, wherein the cross-sections of the support shaft perpendicular to its lengthwise direction are 'D'-shaped in which a portion of a circle is cut, a first diameter which is a dimension in the lengthwise direction of a linear portion from the cross-sections is greater than a dimension of the opened portion, and a second diameter which is a dimension in a direction per¬

il pendicular to the lengthwise direction of the linear portion is less than the dimension of the opened portion so that, in the first position, the support shaft does not allow the opened portion to pass and cannot be separated from the accommodation hole, and in the second position, the support shaft allows the opened portion to pass and can be separated from the accommodation hole .

[5] The wiper arm assembly of claim 4, wherein an interference evasion groove is formed in the support shaft to avoid interference with wall surfaces of the opened portion when the support shaft allows the opened portion to pass in a direction in which the support shaft is separated from the accommodation hole in the second position.

[6] A wiper arm assembly comprising: an arm head including one end fixed on a pivot shaft installed on a body and the other end having a support shaft; a retainer including one end combined with the arm head so that the retainer can rotate around the support shaft, and the other end combined with a blade for wiping a glass of a vehicle; and a tension spring including one end attached to the retainer and the other end attached to the arm head so as to connect and support the retainer and the arm head and to pull the retainer toward the glass of the vehicle within a predetermined rotation angle so that the blade presses against the glass of the vehicle, wherein the retainer comprises an accommodation hole having an opened portion so that the support shaft can be attached to or detached from the retainer through the opened portion in a predetermined position in which the retainer does not exceed the rotation angle, and the support shaft has a first position in which the support shaft cannot be separated from the accommodation hole and a second position in which the support shaft can be separated from the accommodation hole while the support shaft is rotated within the rotation angle, due to a difference in sizes of cross- sections of the support shaft perpendicular to its lengthwise direction.

[7] The wiper arm assembly of claim 6, wherein the cross-sections of the support shaft perpendicular to its lengthwise direction are 'D'-shaped in which a portion of a circle is cut, a first diameter which is a dimension in the lengthwise direction of a linear portion from the cross-sections is greater than a dimension of the opened portion, and a second diameter which is a dimension in a direction perpendicular to the lengthwise direction of the linear portion is less than the dimension of the opened portion so that, in the first position, the support shaft does not allow the opened portion to pass and cannot be separated from the ac- commodation hole, and in the second position, the support shaft allows the opened portion to pass and can be separated from the accommodation hole , and an interference evasion groove is formed in the support shaft to avoid interference with wall surfaces of the opened portion when the support shaft allows the opened portion to pass in a direction in which the support shaft is separated from the accommodation hole in the second position.