Operating angle adjusting structure for wiper

Abstract: An operable angle adjusting structure for a wiper producing a maximally wide wiping angle within the range where wiper arms will not interfere with window pillars and each other and will not require a precision machining apparatus. A drive link (7) includes a ball joint (16a) disposed in one end portion, and the ball joint (16a) is integrally mounted to one surface of an adjusting member (16c) such that the center axis (P) of the ball joint (16a) is eccentric with respect to the center of a screw hole (16d) by a distance α. The adjusting member (16c) is turned to change the axis-to-axis distance between a wiper drive shaft (6) and the ball joint (6a) for proper adjustment.

Description: FIELD OF THE INVENTION The present invention relates to an operating angle adjusting structure for a wiper for wiping windshield surfaces of motor vehicles such as automobiles, buses and trucks. DESCRIPTION OF THE RELATED ART Generally, a wiper has a wiper arm which is driven by a motor to reciprocally swing for wiping a windshield surface. It is desirable for a wiper to have a greater wiping angle for providing a wider field of view. The wiping angle of a wiper arm is determined by an axis-to-axis distance between an axis of a turnable shaft at a proximal end side of a link member and a center axis of a ball joint at a distal end side thereof, the link member being disposed in a power transmission path extending from a motor to a wiper shaft. The longer the axis-to-axis distance, the greater the wiping angle. From this standpoint, it is desirable to set the axis-to-axis distance so that the wiping angle is maximized. Due to manufacturing errors caused when machining and mounting the turnable shaft and the ball joint to the link member, however, the wiping angle may exceed the maximum axis-to-axis distance. This raises a problem that the wiping angle of the wiper arm is increased to such an extent so as to interfere with a pillar. The above problem can be avoided by employing special precision machining which provides higher accuracy than usual, when machining and mounting the turnable shaft and the ball joint to the link member, or by shortening the axis-to-axis distance in anticipation of the manufacture errors. However, the former method has poor production efficiency and requires a special precision machining apparatus, thus increasing the equipment cost. On the other hand, the latter method is free from the problems of the former method, but the wiping angle is necessarily reduced. An opposing type wiper comprises a crank arm rotatably driven by a motor, an intermediate link pivotally supported at a middle position, and a connecting rod disposed between the crank arm and the intermediate link for converting a rotating motion of the crank arm into a reciprocal swing motion of the intermediate link. Further, upper and lower ends of the intermediate link are connected respectively to right and left wiper shafts via drive rods, causing right and left wiper arms to be operated for wiping the windshield surface in oppositely moving relation. Additionally, changes in angular speeds of the right and left wiper arms are set to be asymmetrical therebetween so that wiper blades of the right and left wiper arms are overlapped with each other in their lower inverting positions. Specifically, the right and left wiper blades are laid one above the other without interfering with each other, by setting the angular speed of the overlying wiper arm (on the side of a driver's seat) to be larger than that of the underlying wiper arm (on the side of an assistant's seat) in the vicinity of the lower inverting positions. Thus, the opposing type wiper includes many components, and even a small error significantly affects the wiping angle and often leads to a risk that the wiper arms may interfere with each other. Also, because the angular speeds of the wiper arms are intentionally made different between the driver's side and the passenger;s side, high accuracy is required in setting of the components and setting errors result in a significant influence. FR-A-2356542 discloses an operating angle adjusting assembly substantially in accordance with the pre-characterising part of claim 1. According to the present invention there is provided an operating angle adjusting assembly for a wiper for use on a vehicle to produce a wiping angle initially intended comprising: a drive link; a ball joint attached to a first end of the drive link by a pin having an axis such that the ball joint is eccentric relative to the axis of the pin; a drive rod attached to the first end of the drive link by a ball retainer; and a plate-like adjusting member interposed between the ball joint and the first end of the drive link and being integrally attached to the proximal end of the ball joint such that rotation of the adjusting member adjusts the operating angle between the drive rod and the drive link, and a rotation prevention assembly for preventing rotation between said adjusting member and said drive link, characterised in that the rotation prevention assembly includes at least one projection extending from one of said drive link and said adjusting member, said at least one projection engaging a complementary recess in the other one of said adjusting member and said drive link opposite said at least one projection. One embodiment of the invention provides an operating angle adjusting structure for a wiper having a ball joint disposed in one end portion of a link member and a ball retainer disposed on a connecting rod. The ball retainer is supported by the ball joint in such a manner as to rotate through a spherical slide contact. The ball joint is integrally mounted to one surface of an adjusting member. The adjusting member is attached to one surface of the link member and is rotatable for adjustment through a setting shaft fixedly inserted in the ball joint at an eccentric position with respect to the center axis of the ball joint. In the above operating angle adjusting structure, preferably, an anti-rotation assembly is provided for checking rotation of the adjusting member after adjustment. The anti-rotation assembly is disposed between the other surface of the adjusting member and the one surface of the link member opposing each other. With the present invention arranged as set forth above, a maximally wide wiping angle can be realized within the range such that the wiper arms will not interfere with the window pillars and each other, without requiring a precision machining apparatus. The invention will be described now by way of example only, with particular reference to the accompanying drawings. In the drawings: Fig. 1(A) is a schematic front view of an opposing type wiper, and Fig. 1(B) is a front view of principal parts of the wiper. Fig. 2 is a perspective view of a drive link mechanism.Fig. 3 is a front view of the drive link mechanism with a drive link partly broken away. Fig. 4 is a plan view of the drive link. Fig. 5 is a bottom view of the drive link. Fig. 6(A) is a front view of a ball joint, Fig. 6(B) is a plan view of the ball joint, Fig. 6(C) is a side view of the ball joint partly broken, and Fig. 6(D) is a sectional view, in the developed form, of an adjusting member having projections. Fig. 7 is a view of a mechanism for adjusting an eccentric condition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to the accompanying drawings. In the drawings, denoted by 1 is an opposing type wiper. The wiper 1 comprises a motor 2 equipped with an integral speed reducing mechanism. A crank arm 3 is integrally mounted to an output shaft of the motor 2 for rotation with the output shaft. An intermediate link 4 is pivotally supported at a middle position about a pivot 4a. A connecting rod 5 is coupled between a lower end of the intermediate link 4 and a distal end of the crank arm 3. A pair of right and left wiper drive shafts 6 are disposed laterally, one on either side of the intermediate link 4. A right drive rod 8 is coupled between a drive link 7 of the right wiper drive shaft 6 and an upper end of the intermediate link 4. A left drive rod 9 is coupled between a drive link 7 of the left wiper drive shaft 6 and a lower end of the intermediate link 4. A pair of right and left wiper arms 10 are integrally mounted to the right and left wiper drive shafts 6, respectively. In the above arrangement, the rotating motion of the crank arm 3 driven by the motor 2 is converted into a reciprocal swing motion of the intermediate link 4 through the coupling of the crank arm 3 to the connecting rod 5. As the upper and lower ends of the intermediate link 4 swing transversely in opposite directions, the drive links 7 of the right and left wiper drive shafts 6 which are operatively coupled to the upper and lower ends of the intermediate link 4 through the drive rods 8 and 9, respectively, are turned to operate the wiper arms 10 joined to the right and left wiper drive shaft 6 for wiping the windshield surface in oppositely moving relation. The angular speeds of the left and right wiper arms 10 are set to change asymmetrically therebetween in the vicinity of their lower inverting positions, as described later, so that wiper blades 11 overlap vertically in the lower inverting position without interfering with each other. The right wiper blade 11 on the driver's seat side (Dr) overlies the left wiper blade 11 on the passenger's seat side. A drive unit 12 is constructed by integrally mounting the motor 2 and the pivot point 4a of the intermediate link 4 to a motor bracket 13. The crank arm 3, the connecting rod 5 and the intermediate link 4 are also mounted to the drive unit 12. The length of the connecting rod 5 and its coupling position to the intermediate link (i.e., the distance and the phase angle with respect to the link pivot point) are set so that the actual angular speed of the intermediate link 4 is changed substantially symmetrically between the right and left sides. A pair of right and left wiper shaft sleeves 14 is constructed by mounting the wiper drive shaft 6 and the drive link 7 to a wiper shaft bracket 15. The wiper shaft sleeves 14 are disposed in respective positions laterally of the drive unit 12 to the right and left. The wiper shaft sleeves 14 are operatively coupled to the intermediate link 4 through the drive rods 8 and 9. The lengths of the drive rods 8 and 9 and their coupling positions to the intermediate link 4(i.e., the distances and the phase angles with respect to the link pivot point) are set so that angular speeds of the right and left wiper arms 10 are changed asymmetrically between the right and left sides. Specifically, the wiper blades 11 of the right and left wiper arms 10 are laid one above the other at the lower inverting positions without interfering with each other. This is accomplished by setting the angular speed of the right wiper arm 10 to be larger than that of the left wiper arm 10 in the vicinity of the lower inverting positions. In this respect, since the angular speed of the intermediate link 4 is set to change substantially symmetrically between the right and left sides as described above, the angular speeds of the right and left wiper arms 10 are set to change asymmetrically between the right and left sides based on only setting of the lengths of the drive rods 8 and 9 and setting of their coupling positions to the intermediate link 4. When the wiper motor 2 is energized to rotate, the wiper arms 10 are angularly moved in a reciprocal manner, causing the wiper blades 11 to wipe the windshield surface W. Each of the wiper drive shafts 6 is integrally fixed to a proximal end of a link body 7a of the drive link 7. An attachment hole 7b is bored in one end portion of the link body 7a, and the one end portion of the link body 7a has a peripheral edge 7c formed into an arc shape concentric with the attachment hole 7b. A joint assembly 16 for coupling the link body 7a and each of the right and left drive rods 8 and 9 comprises a ball joint 16a attached to the one end portion of the link body 7a. A ball retainer 16b integrally provided on each of the right and left drive rods 8 and 9 is fitted over the ball joint 16a so that it can rotate through a spherical slide contact. The ball joint 16a is attached to one surface of the link body 7a in such a manner that it is eccentric with respect to the attachment hole 7b by a distance α. More specifically, a proximal end of the ball joint 16a is integrally attached to one surface of a plate-like adjusting member 16c. A screw hole 16d to which a screw pin 17 (described below) for fixing the ball joint 16a is inserted is bored in each of the adjusting member 16c and the ball joint 16a at a position eccentric with respect to the center axis of the ball joint 16a by the distance α. The ball joint 16a may be mounted to one surface of the link body 7a by placing the adjusting member 16c into abutment against one surface of the link body 7a. The screw pin 17 is screwed into the link body 7a until it penetrates and enters the screw holes 16d in the adjusting member 16c and the ball joint 16a. The axis-to-axis distance D between the center axis of the ball joint 16a and the axis of the wiper shaft 6 can be adjusted by turning the adjusting member 16c about the axis of the screw pin 17 in a condition when the screw pin 17 has been loosened. The adjusting member 16c has a peripheral edge with an arc shape concentric with the screw hole 16d. The adjusting member 16c has a plurality of rectangular anti-rotation projections 16e formed in a radial pattern on a surface of the adjusting member 16c. The projections 16e may have a rectangular cross-section, as shown in Fig. 6(D). The link body 7a has a plurality of recesses 7d formed on a surface in a radial pattern to receive the anti-rotation projections 16e. The projections 16e when located within the recesses 7d prevent the adjusting member 16c attached to the link body 7a from rotating. Alternatively, the rectangular projections may extend from the linkbody 7a and engage recesses in the adjusting member 16c. A position adjusting tongue 16f projects from a peripheral edge of the adjusting member 16c to extend in a radial direction Y passing the center O of the screw hole 16d substantially perpendicularly to a straight line X that passes the center O of the screw hole 16d and the center axis P of the ball joint 16a. The tongue 16f is bent toward the other surface of the link body 7a and has a nearly L-shape of which leg is extended facing the peripheral edge 7c of the one end portion of the link body 7a. The position of the ball joint 16a can be adjusted within a range Z exceeding 180 degrees. The tongue 16f comes into abutment against the respective side edges of the link body 7a limiting the adjusting range of the joint ball 16a. Additionally, a notch 16g is formed in a distal end of the tongue 16f. The position of the ball joint 16a may be adjusted by inserting a tool such as a screwdriver into the notch 16g. On an opposite surface of the link body 7a, graduations 7e numbered from "1" to "9" indicate respective positions of the tongue 16f for adjustment. The link body 7a is stepwisely curved at an intermediate portion such that one surface of the link body 7a is recessed toward the opposite surface thereof by a distance corresponding to the thickness C of the adjusting member 16c. The one surface of the link body 7a at the end adjacent the wiper drive shaft 6 is substantially flush with the one surface of the adjusting member 16c. In the embodiment of the present invention arranged as described above, since the connecting rod 5, which operatively couples the crank arm 3 driven by the motor to rotate and the intermediate link 4 coupled to the right and left wiper drive shafts 6 through the drive rods 8 and 9, is set in its length and its coupling positions to the intermediate link 4 so as to change the actual angular speed of the intermediate link 4 substantially symmetrically between the right and left sides. The angular speeds of the right and left wiper arms 10 are changed asymmetrically between the right and left sides based on setting of the lengths of the drive rods 8 and 9 and setting of their coupling positions to the intermediate link 4. The right and left wiper arms 10 are operated to swing reciprocally, causing the wiper blades 11 to wipe the windshield surface W. When the adjusting member 16c attached to the ball joint 16a is turned to a desired position about the axis of the screw pin 17, the ball joint 16a is turned eccentrically with respect to the center of the screw hole 16d. As a result, the axis-to-axis distance between the ball joint 16a fixed by the screw pin 17 and the wiper drive shaft 6 changes. With this arrangement, the wiping angle of each wiper blade can be simply adjusted to a maximum angle initially intended within the range where the wiper blade will not strike against the pillar, and manufacturing errors of individual products can be surely accommodated. Unlike the prior art, special precision machining which provides higher accuracy than usual is not required to machine and mount the turnable shaft (wiper driver shaft) and the ball joint to the link member. As described above, in an embodiment of the present invention, the ball joint 16a attached in an eccentric condition is turned about the center of the screw hole 16d to adjust the axis-to-axis distance between the ball joint 16a and the wiper drive shaft 6 for thereby absorbing the manufacturing errors. The wiping angle can be set to an ideal value depending on an extent of the windshield surface, an angle of the windshield surface with respect to the vehicle body, etc. within the range where the wiper arms will not interfere with the window pillars and each other. As a result, the ideal wiping angle initially intended can be easily realized without reducing the wiping angle, i.e., shortening the axis-to-axis distance, to prevent the wiper arms from interfering with the window pillars and each other, nor requiring special precision machining that has poor production efficiency. Also, after the ball joint 16a is adjusted, the position of the ball joint 16a is prevented from rotating by engagement between the rectangular projections 16e on the adjusting member 16c and the recesses 7d formed in the link body 7a. As a result when any external force is applied to the wiper arm 10 tending to rotate the ball joint 16a about the axis of screw pin 17, the rotational force produced is borne by vertical walls of the rectangular projections 16e and recesses 7d engaging each other. Accordingly, the ball joint 16a is prevented from deviating from its adjusted position, resulting in high reliability. Additionally, the ball joint 16a is positioned and prevented from rotating by the screw pin 17 by which the ball joint 16a is fixed to the link body 7a and the engagement of the rectangular projections 16e with recesses 7d. The stresses produced by the rotating force and the pushing/pulling force exerted on the joint ball 16a are not concentrated on one point, but borne in a distributed manner. Thus, the rotating force is borne by the rectangular projections 16e and recesses 7d engaging with each other, and the pushing/pulling force is borne by the screw pin 17 fixedly screwed in place. As a result, the wiper has superior durability. The adjusting member 16c can be conveniently adjusted by using the tongue 16f projecting from the adjusting member 16c. Since the notch 16g is formed in the tongue 16f, the adjustment can be made by inserting a tool such as a screwdriver to the notch 16g. The adjusting operation can be easily performed even in a condition where the wiper is assembled on the vehicle body and it is difficult for an assemblyman to access to the tongue 16f by a finger. The tongue 16f projects in the radial direction Y of the screw hole 16d substantially perpendicular to the straight line X that passes the center O of the screw hole 16d and the center axis P of the ball joint 16a. The center axis P of the joint ball 16a is positioned, as shown in Fig. 4, at the central position of the adjustment range, i.e., with the tongue 16f set to the position of the number "5" on the gradations. In such an orientation, the axis-to-axis distance between the axis Q of the wiper drive shaft 6 and the center axis P of the ball joint 16a is substantially equal to the distance D between the center O of the screw hole 16d and the axis Q of the wiper drive shaft 6. When the tongue 16f is turned toward the "+" mark, the center axis P of the ball joint 16a is displaced toward the wiper drive shaft 6 while following the path in the form of an arc-shaped line about the center O of the screw hole 16d, as shown in Fig. 7. Accordingly, the axis-to-axis distance between the axis Q of the wiper drive shaft 6 and the center axis P of the ball joint 16a can be adjusted to become shorter (i.e., increasing the wiping angle of the wiper arm). The amount by which the axis-to-axis distance is adjusted is maximized when the tongue 16f is swung from the central position to the number "9" on the gradations by 90 degrees. The maximum amount of adjustment corresponds to the eccentricity a of the ball joint 16a. When the tongue 16f is turned toward the "-" mark, the axis-to-axis distance can be adjusted to become longer (i.e., reducing the wiping angle of the wiper arm) by a distance corresponding to the maximum eccentricity a. As a result, the axis-to-axis distance can be adjusted totally by an amount twice the eccentricity a, which is advantageous in providing a wide adjustment range. The adjustment of the axis-to-axis distance is restricted by tongue 16f abutting the link body 7a in such a manner as not to exceed the positions between which the amount of adjustment is doubled (i.e., the positions of numbers "1" and "9" on the gradations). There is no risk that the ball joint 16a may be excessively rotated and the assemblyman may miss the adjustment position. Moreover, the gradations are numbered by integers from "1" to "9", to avoid misreading by the assemblyman which may occur when the scale is graduated by "0" at the central value and then "+1" to "+4" and "-1" to "-4" successively from "0" on each side. The tongue 16f is bent toward the other surface of the link body 7a to have substantially an L-shape and the peripheral edge 7c of the one end portion of the link body 7a is in the form of an arc about the center of the screw hole 16d. The adjusting operation can be performed by turning the tongue 16f along the arc-shaped peripheral edge 7c with good working efficiency. Since the gradations 7e are formed on the other surface of the link body 7a, the assemblyman can recognize the adjustment position in a quantitative manner by looking at the graduations 7e. As a result, the axis-to-axis distance can be easily adjusted with higher accuracy. Still another advantage, the link body 7a is stepwisely curved in its intermediate portion such that the one surface of the link body is recessed toward the other surface thereof by a distance corresponding to the thickness C of the adjusting member 16c. The one surface of the link body 7a on the same side as the wiper drive shaft 6 is kept substantially flush with the one surface of the adjusting member 16c. As a result, the link body 7a can be flat on the side of one surface thereof even with the presence of the adjusting member 16c thereon. The present invention is not limited to the above-described embodiment. For example, the present invention is also applicable to a ball joint by which a connecting rod is coupled to, rather than the drive link, a drive arm having a proximal end integrally fixed to the output shaft of the wiper motor. In this modified case, the output shaft corresponds to the wiper shaft and the crank arm corresponds to the wiper link. Further, the present invention is similarly applicable to a ball joint for the intermediate link. In short, according to the present arrangement described above, the axis-to-axis distance between the ball joint and the wiper drive shaft can be adjusted by turning the ball joint to which the connecting rod is coupled in such a manner that it can rotate through a spherical slide contact, about the axis of the screw pin by which the ball joint is attached to the link member. As a result, the manufacturing errors can be absorbed and the wiping angle of each wiper arm can be set to a maximum value depending on an extent of the windshield surface, an angle of the windshield surface with respect to the vehicle body, etc. within the range where the wiper arms will not interfere with the window pillars and each other. Thus, the maximum wiping angle initially intended can be easily realized without reducing the wiping angle, i.e., shortening the axis-to-axis distance, to prevent the wiper arms from interfering with the window pillars and each other, nor requiring special precision machining that has poor production efficiency.

Claims: An operating angle adjusting assembly for a wiper for use on a vehicle to produce a wiping angle initially intended comprising: a drive link (7); a ball joint (16a) attached to a first end of the drive link (7) by a pin (17) having an axis such that the ball joint (16a) is eccentric relative to the axis of the pin; a drive rod (8, 9) attached to the first end of the drive link by a ball retainer (16b); and a plate-like adjusting member (16c) interposed between the ball joint (16a) and the first end of the drive link (7) and being integrally attached to the proximal end of the ball joint (16a) such that rotation of the adjusting member (16c) adjusts the operating angle between the drive rod (8, 9) and the drive link (7), and a rotation prevention assembly for preventing rotation between said adjusting member (16c) and said drive link (7), characterised in that the rotation prevention assembly includes at least one projection (16e) extending from one of said drive link (7) and said adjusting member (16c), said at least one projection engaging a complementary recess (7d) in the other one of said adjusting member (16c) and said drive link (7) opposite said at least one projection. An operating angle adjusting structure for a wiper according to claim 1, wherein a tongue (16f) projects from said adjusting member (16c) for adjustment of its position. An operating angle adjusting structure for a wiper according to claim 2, wherein said tongue (16f) is bent toward the other surface of said drive link (7) so as to have substantially an L-shape, and the one end portion of said drive link (7) has a peripheral edge (7c) formed into an arc shape about the axis of said pin (17). An operating angle adjusting structure for a wiper according to claim 3, wherein graduations (7e) which provide indexes for positions of said tongue (16f) are formed on the other surface of said drive link (7). An operating angle adjusting structure for a wiper according to any one of claims 1 to 4, wherein the axis-to-axis distance between a drive shaft and said joint ball is adjusted to change over a range which is twice the eccentricity of said ball joint (16a) from the axis of said pin (17).

Inventors: HOSHINO TAKASHI, HOSHINO, TAKASHI
Applicants: MITSUBA CORP, MITSUBA CORPORATION
Application year: 1995
Main classification: B60S1
IPC codes: B60S1, F16C3