WINDSHIELD WIPER

Abstract: A windshield wiper including an arm head (1) being rotatably connected to a stationary part of a vehicle, a main arm (2) rotatively supported on the arm head and being connected to a wiper blade, and a sub-arm (3) supporting a wing (4) and being rotatively supported on the arm head. The axis (C-C) of the rotative movement of the sub-arm (3) and that (B-B) of the main arm (2) make an acute angle (α) therebetween whereby a part of the air force acting on the wing (4) is transmitted to the main arm (2) as determined by a partial force defined by the acute angle.

Description: Field of the Invention The present invention relates to a windshield wiper and, particularly to a windshield wiper having a device for preventing the lift up phenomenon or a pressure increasing device such as a wing. Description of Prior Art In a windshield wiper for cleaning a windshield of a vehicle, when the vehicle runs at a high speed, the wiper tends to lift up from the surface of the windshield, which deteriorates the wiping property and, in the worst case, the wiperblade of the wiper device will separate from the glass surface and, as a result, the glass surface will be damaged. For preventing such the lift up phenomenon various types of pressure increasing devices have been proposed. Such devices comprise a wing device, a pressure increasing actuator device with a control circuit therefor, a wiper device having a twisted arm head and the like. The wiper having a wing device has shortcomings such that the wing has a relatively large shape which increases the size and weight of the wiper device, the pressure decreases by the wind in the reverse direction, and the visibility of the driver deteriorates. The wiper device having a pressure increasing actuator and an electronic control circuit is complicated in construction and is expensive. Fig.18 through Fig.20 show one example of prior art wiper device having a twisted arm head. In the drawings, an arm head 1 is mounted on a stationary part (not shown) of a vehicle and oscillates around an axis A-A, a wiper arm 2 is mounted on the arm head 1 and oscillates around an axis B-B. The axis A-A intersects with the axis B-B at an acute angle, while in usual wiper devices the axes A-A and B-B intersect orthogonally. The device enables to utilize the air stream acting on the wiper arm 2 and on a wiperblade (not shown) so as to increase the pressing force. The device can effectively utilize the wind stream, but friction force acting between the windshield surface and the blade rubber will also acts increasing the pressing force, which increases further the friction force and tends to deteriorate the wiping property and to overload the wiper motor and the like. Further, the pressing force will also decreases under the wind of the reverse direction. The present invention has been made in view of the circumstances aforementioned, and aims to provide a windshield wiper which can effectively utilize the wind acting on the wing. Summary of the Invention According to the invention, there is provided a windshield wiper including an arm head being rotatively connected to a stationary part of a vehicle, a main arm rotatively supported on the arm head and being connected to a wiper blade, a sub-arm supporting a wing and being rotatively supported on the arm head, characterized in that the axis of the oscillation of the sub-arm and that of the main arm with respect to the arm head make an acute angle therebetween whereby a part of the air force acting on the wing is transmitted to the main arm through the sub-arm. According to the invention, only the main arm acts when the vehicle is not moving, and a part of the air force acting on the wing is additionally applied on the wiperblade when the vehicle is running, thus, the force acting on the wiperblade can reliably be controlled, and it is possible to maintain the wiping property and to avoid the overload on a wiper motor. Further developments in line with the invention defined in claim 1 are referred to in the dependent claims. Brief Description of the Drawings Further objects and effects of the invention will become apparent from the following detailed description in conjunction with the drawings, in which: Fig.1 is a schematic plan view of a windshield wiper according to a first embodiment of the present invention with a wiperblade thereof being omitted; Fig.2 is a side view of the wiper of Fig. 1; Fig.3 is a schematic end view as viewed from the left end of Fig. 2; Fig.4 is a diagram showing the relationship between the air stream and the axes of rotative movement according to the first embodiment; Fig. 5 is a schematic plan view similar to Fig. 1 but showing a second embodiment of the invention; Fig.6 is a schematic side view of Fig.5; Fig.7 is a section view taken along line B-B in Fig.5; Fig.8 is a section view taken along line C-C in Fig.5; Fig.9 is a section view similar to Fig.8 but showing the condition when the wiper takes rock back condition; Fig.10 is a schematic view showing a groove formed in a side surface of the arm head of the second embodiment; Fig.11 is a partial sectional view showing the depth of the groove of Fig. 10; Fig.12 is a schematic plan view of a third embodiment of the present invention; Fig.13 is a schematic side view of Fig. 12; Fig.14 is a view similar to Fig. 13 but showing the condition when the wiper is moving into rock back condition; Fig.15 is a sectional view taken generally along line B-B in Fig. 12; Fig. 16 is a sectional view taken generally along line E-E in Fig. 12; Fig.17 is a sectional view taken generally along line F-F in Fig. 12; Fig.18 is a schematic plan view showing a prior art windshield wiper with a wiperblade thereof being omitted; Fig.19 is a schematic side view of Fig. 18, and Fig.20 is a graph showing the relationship between the rotation of the wiper arm and the arm head according to the invention. Detailed Description of Preferred Embodiments The first embodiment according to the invention shown in Figs. 1 through 3 comprises an arm head 1 which is adapted to be mounted on a stationary part (not shown) of a vehicle and is reciprocatingly rotatable around the axis A-A, a main arm 2 rotatively mounted on the arm head 1 around the axis B-B with a wiperblade (not shown) being mounted on a tip end 2a, a sub-arm 3 supporting a wing 4 and being rotatively mounted on the arm head 1 around the axis C-C, a pivot pin 5 between the arm head 1 and the main arm 2 and defining the axis B-B, a pivot pin 6 between the arm head 1 and the sub-arm 3 and defining the axis C-C, and a main spring 8 acting between the arm head 1 and the main arm 2 through a hook 9. The sub-arm 3 has a generally inverted U-shape or a channel like shape and overlaps the main arm 2 of the similar cross-section. As shown in Figs.3 and 4, the axes B-B and C-C define an acute angle α therebetween, thus, a partial force of the aerodynamic force acting on the wing 4 acts on the main arm 2 in vertical downward direction. The wing 4 may have a vertical wind receiving surface which is vertical to the windshield surface or opposing to the direction of the wind, by which the interference on the visible field of the driver of the vehicle can be minimized. But the wing 4 may have an inclined surface. In assuming that the angle between axes B-B and C-C is α, the force acting on the wing 4 is F and the pressing force transmitted to the main arm 2 from the sub-arm 3 is P, then, P = F·sinα·cosα Shown at 10 in Fig.2 is a sub-spring acting between the main arm 2 and the sub-arm 3 to prevent the sub-arm 3 separating from the main arm 2. In particular, a wind in the reverse direction may sometimes push up the sub-arm when the sub-spring 10 is not provided. Fig. 5 through Fig. 11 show the second embodiment of the invention which is generally similar to the embodiment of Figs.1 through 3 and corresponding parts are denoted by the same reference numerals, and the description is omitted. The main arm 2 is mounted on the arm head 1 through the pivot pin 5 and is rotative around the axis B-B similar to the first embodiment. But, the sub-arm 3 is mounted on the arm head 1 through two ball joint like connecting portions consisting of a semi-spherical projection 11 on the sub-arm 3 and a semi-spherical recess 12 in the upper left (Fig.8) portion in the arm head 1, and a semi-spherical projection 13 on the sub-arm 3 and a semi-spherical recess 14 in the lower right (Fig. 8) portion in the arm head 1. These connecting portions constitute ball joints and define the axis C-C which makes the angle α similar to the first embodiment. The operation, in particular, the force transmitting function of the second embodiment is the same to that of the first embodiment. The spherical recess 14 is connected to a circular groove 15 as shown in Figs. 6, 10 and 11 which enables the spherical projection 13 to move along the groove 15 of a shallow depth as compared with the spherical recess 14 when the main arm 2 takes the rock back condition so that the sub-arm 3 will easily and smoothly follow the movement of the main arm 2. Fig. 12 through Fig. 17 show the third embodiment of the invention which is generally similar to the first and second embodiments and corresponding parts are denoted by the same reference numerals. The left (Fig. 16) side of the sub-arm 3 is pivotably supported on a pivot pin 6′ which is mounted on the arm head 1 and acts to support the hook 9, but the right side of the sub-arm 3 has an elongated opening 17 for receiving the pivot pin 6′ as shown in Fig. 13. Further, a projection 16 is formed on the right side surface of the arm head 1 so as to abut with the rear upper end of the sub-arm 3 during the normal operating condition. The abutting portion between the projection 16 and the sub-arm 3 and the left end portion of the pivot pin 6′ act to define the axis C-C as shown in Fig. 17 which makes the angle α to the axis B-B defined by the pivot pin 5, thereby the wind force acting on the wing 4 is transmitted to the main arm 2 similar to preceding embodiments. When the main arm 2 takes rock back condition as shown in Fig.14, the rear end of the sub-arm 3 separates from the projection 16 so that the sub-arm 3 rotatively moves around the pivot pin 6′ which is parallel to the pivot pin 5. Thus, the rock back movement of the sub-arm 3 is smooth and easy. As described heretofore, according to the invention, only the main arm acts when the vehicle is not moving, and a portion of the air force acting on the wing is applied additionally on the main arm to increase the pressing force when the vehicle is running, thus, the force acting on the wiperblade can be reliably controlled, and it is possible to maintain reliably the wiping characteristics and to avoid excessive load on a wiper motor. Although the various aspects of the present invention have been described with respect to its preferred embodiments, it will be understood that the invention is not limited to the embodiments and is entitled to cover within the full scope of the appended claims.

Claims: A windshield wiper including an arm head (1) being rotatably connected (A-A) to a stationary part of a vehicle, a main arm (2) rotatively supported (5,B-B) on the arm head (1) and being connected to a wiper blade, a sub-arm (3) supporting a wing (4) and being rotatively supported (6, C-C) on the arm head, characterized in that the axis (C-C) of the rotative movement of the sub-arm (3) and that (B-B) of the main arm (2) with respect to the arm head (1) make an acute angle (α) therebetween whereby a part of the air force acting on the wing (4) is transmitted to the main arm (2) through the sub-arm (3). A windshield wiper according to claim 1, wherein said wing (4) has a wind receiving surface substantially extending orthogonal to the surface of the windshield. A windshield wiper according to claim 1, wherein said wing (4) has a generally flat or recessed wind receiving surface which is inclined in the rear and upward direction. A windshield wiper according to claim 1, wherein a sub-spring (10) is provided between the main arm (2) and the sub-arm (3). A windshield wiper according to claim 1, wherein the main portion of the sub-arm (3) has a generally inverted U-shaped or a channel like cross-section and extends substantially overlying the main arm (2). A windshield wiper according to claim 5, wherein a pivot pin (5, B-B) is mounted on the arm head (1) to mount rotatively the main arm (2) and another pivot pin (6, C-C) is mounted on the arm head (1) to mount rotatively the sub-arm (3), said pivot pins (5,6) defining the acute angle therebetween. A windshield wiper according to claim 5, wherein pivot portions are provided respectively between the opposite side portions of the rear end portion of the sub-arm (3) and corresponding side surfaces of the arm head (1), said pivot portions defining an axis (C-C) of rotative movement of the sub-arm (3). A windshield wiper according to claim 7, wherein said pivot portions respectively comprise semi-spherical recesses (12,14) formed in the side surfaces of the arm head (1) and semi-spherical projections (11,13) formed on the sub-arm (3). A windshield wiper according to claim 8, wherein one of said semi-spherical recesses in the arm head (1) is continued to a shallow groove (15) extending along a circular arc. A windshield wiper according to claim 5, wherein a pivot pin (6, C-C) is mounted on the arm head (1) to mount rotatively the main arm (2), another pivot pin (5, B-B) is also mounted on the arm head (1) which passes through an elongated opening (17) in one side of the sub-arm (3) and through a circular opening in the other side of the sub-arm (3), the rear end of said one side of the sub-arm (3) engages normally with a stop or a projection (16) formed on the arm head (1), said engagement between the stop (16) and the sub-arm (3) and the circular opening in said the other side of the sub-arm (3) defines said axis (C-C) of the rocking movement of the sub-arm (3). A windshield wiper according to claim 10, wherein when the pivot pin (6′, C-C) between the arm head (1) and the sub-arm (3) takes the position near to one end of the elongated opening (17) the axis (C-C) of rotative movement of the sub-arm (3) is parallel to that of the main arm (2) and, when the pivot pin (6′, C-C) takes the position near to the other end of the elongated opening (17) the axes of rotative movement of the sub-arm (3) and the main arm (2) make an acute angle (α).

Inventors: ARAI, MASARU C/O NIPPON WIPERBLADE CO., LTD., SAITA, ITSURO C/O NIPPON WIPERBLADE CO., LTD.
Applicants: NIPPON WIPERBLADE CO., LTD.
Application year: 1989
Main classification: B60S1
IPC codes: B60S1