JPH04193650A - Driving device for wiper - Google Patents

Abstract

PURPOSE:To restrain fluctuation of torque so as to flatten torque characteristic by providing a first rotor which is rotated by a wiper motor and a second rotor which is rotated while being joined to the first rotor and which has an output shaft to which a crank arm is mounted, and specifying the outer shape of each rotor. CONSTITUTION:A driving device S for a wiper comprises a wiper motor 1, a worm gear 2, and an eccentric gear transmission mechanism 3, etc., and provides reciprocating and oscillating motion to the wiper via a crank arm 16a. The eccentric gear transmission mechanism 3 has two gears 11a, 11b and the second gear 11b is affixed to an output shaft 13 and meshes with the first gear 11a. The angular velocity ratio of the gears 11a, 11b, i.e., the ratio of the angular velocity of the gear 11b to that of the gear 11a consists of two ranges, i.e., a constant range wherein the angular velocity ratio is constant at its maximum value during rotation of the output shaft 13, and a variable range wherein the angular velocity ratio is varied in roughly sine wave on both sides of this constant angular velocity ratio range, and the outer shape of each gear 11a, 11b is such that the rotary angle of each gear 11a, 11b is in roughly one-to-one relationship.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a wiper drive device, and particularly relates to an improvement in output torque characteristics of a wiper drive device using an eccentric gear mechanism.

[Prior Art] Conventionally used wiper devices include, for example, a wiper drive device composed of a wiper motor and a crank arm connected to the output shaft of the wiper motor, which applies rotational motion to a pivot shaft via a link mechanism. It is known that a wiper arm is fixed to this pivot shaft to obtain a reciprocating swinging motion of the wiper. By the way, in a wiper device having such a configuration,
It is well known that the torque transmitted from the wiper drive device to the pivot shaft varies depending on the positional relationship between the crank arm and the link rod that constitutes the link mechanism. Therefore, depending on the mutual positional relationships among the crank arm, link rod, and swing lever, there is a risk that the torque transmitted to the pivot shaft will not be sufficiently satisfied near the center of the wiping area of the wiper, resulting in the wiper stalling.

This is particularly problematic when driving at high speeds or in cold regions where large motor torque is required.

Therefore, in order to increase the wiping force near the center of the wiper's wiping area, for example, the rotation of the wiper motor is outputted via an elliptical gear transmission mechanism, and from the motor output shaft near the center of the wiper's wiping area to the pivot shaft. Some proposals have been made to increase the transmission torque of
(See September 15, 1996, 1h49-035).

[Problem to be solved by the invention] However, in the wiper drive device using the elliptical gear as described above, although it is possible to improve the torque transmission efficiency,
Looking at the characteristics of the output torque and rotational speed on the motor shaft of the wiper motor, as shown by the solid line in Figure 4B, the distribution of the link mechanism due to the limited mounting space in the vehicle is due to imbalance, and the ratio of the link mechanism to the crank rotation angle increases. Load torque imbalance may occur.

Furthermore, as for the rotation speed, as shown by the two-dot chain line in the same figure, it changes with the fluctuation of the torque.

As a result, there is a protrusion in the torque characteristics, so a wiper motor must be selected that has a rating that can accommodate this protrusion value. You must use a motor that has one. This creates a problem in that the device configuration is wasteful and the price of the device increases.

Furthermore, the variation in the number of rotations of the wiper motor causes the wiper motor to generate whirring noise, causing a problem of becoming a noise source.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a wiper drive device that flattens the torque characteristics by suppressing fluctuations in the torque transmitted from the output shaft of the wiper motor to the pivot shaft as much as possible, and generates less noise from the wiper motor. It is something to do.

[Means for Solving the Problems] The present invention has been made to solve the above problems, and a wiper drive device according to the present invention includes a wiper motor, a first rotating body rotated by the wiper motor, and a wiper drive device according to the present invention. , a second rotating body that rotates in conjunction with the first rotating body, and an output shaft that serves as a rotation center of the second rotating body and to which a crank arm is attached, the wiper drive device comprising: The first rotating body and the second rotating body have an angular velocity ratio, which is a ratio of the angular velocity of the first rotating body to the angular velocity of the second rotating body, during one rotation of the output shaft. The rotation angle of the first rotating body consists of a constant region in which the angular velocity ratio is constant at a maximum value, and a changing region in which the angular velocity ratio changes approximately sinusoidally on both sides of this constant angular velocity ratio region. and the rotation angle of the second rotating body have an outer shape that corresponds approximately one-to-one.

[Operations] Therefore, in the wiper drive device according to the present invention,
In order to have a region in which the angular velocity ratio of the first rotating body, which is the ratio of the angular velocity of the first rotating body to the angular velocity of the output shaft, is constant at the maximum value during one rotation of the output shaft, this angular velocity In a constant speed ratio range, the torque transmitted from the output shaft of the wiper motor to the pivot shaft is constant. That is, since there is no longer a portion where the torque protrudes as in the prior art, the object of the present invention, which is to flatten the torque characteristics by suppressing fluctuations in the torque as much as possible, can be achieved.

In addition, in the above-mentioned constant torque range, the rotational speed of the wiper motor is also approximately constant, so the wiper motor no longer generates whine due to torque fluctuations as in the past, which reduces the noise generated from the wiper motor. Other objects of the invention can be achieved.

[Example] Hereinafter, an example of the present invention will be briefly described with reference to the drawings. Note that the members, arrangement, etc. described below do not limit the present invention, and can be variously modified within the scope of the spirit of the present invention.

FIG. 1 shows an embodiment of the wiper drive device according to the present invention, FIG. 1A is a plan view including a partial cross section of the device S, and FIG. 1B is a plan view including a partial cross section of the device S. FIG.

Further, FIG. 2 shows a schematic configuration diagram of the device S in a usage state.

This device S is composed of a wiper motor 1, a ohm gear 2, an eccentric gear transmission mechanism 3, a housing 4, etc., and includes a crank arm 16a fixed to an output shaft 13 of the eccentric gear transmission mechanism 3. It is connected to the link mechanism 16 and the wiper arm 15b via the link mechanism 16 and the wiper arm 15b to give the wiper 15 reciprocating rocking motion.

The wiper motor 1 has a well-known configuration, and includes a rotor 6 and the like housed inside a motor yoke 5. A housing 4 is connected to a motor yoke 5 of this wiper motor 1 . A ohm gear 2 and the like, which will be described later, are housed within the housing 4.

The rotating shaft 6a of the wiper motor 1 projects from the motor yoke 5 into the above-mentioned housing 4, and within the housing 4, a ohm 2a is formed at the tip of the rotating shaft 6a.

The housing 4 houses the ohm gear 2 and the eccentric gear transmission mechanism 3, and is composed of an upper housing 4a and a lower housing 4b.
is connected to the motor yoke 5 of the wiper motor 1 described above by screws or the like. The lower housing sink 4a is screwed to the lower housing sink 4b at appropriate locations, and the upper housing 4a and lower housing 4b can be separated in the vertical direction in FIG. 1B.

Inside the housing 4, the worm gear 2 is composed of the above-mentioned worm 2a and a worm wheel 2b that meshes with the worm 2a. The ohm wheel 2b is fixed to a shaft 7, and the upper end 7a of the shaft 7 is supported in a bearing recess 8 formed in the upper housing 4a through a bearing 9a such as a radial bearing. There is. On the other hand, the lower end portion 7b is connected to the lower housing 4b.
The shaft supports 10a are respectively inserted into concavely formed shaft supports 10a.

Further, in FIG. 1B, an eccentric gear transmission mechanism 3 is provided above the worm gear 2.

The eccentric gear transmission mechanism 3 is composed of a first gear 11a as a first rotating body and a second gear 11b as a second rotating body, and in this embodiment, the first gear 11a is fixed to the above-mentioned shaft 7 on one side 12 of the worm wheel 2b.

Further, the second gear 11b as a second rotating body is fixed to the output shaft 13 and meshes with the first gear 11a as the first rotating body. This second gear 1
The output shaft 13 to which the output shaft 1b is fixed has an upper end portion 13a protruding from the upper housing 4a to the outside. That is, a shaft support part 14 is formed protruding from the upper housing 4a, and a shaft hole 14a through which the output shaft 13 is inserted is formed in the shaft support part 14. Bearing 9b such as a bearing.

The output shaft 13 is rotatably supported by the shaft support portion 14 via the shaft 9c. Further, the lower end portion 13b of the output shaft 13 is formed in a concave shape in the lower housing 4b, and is supported by a bearing portion 10b.

A screw (not shown) is formed on the upper end 13a of the output shaft 13, and one end 19 of a crank arm 16a forming a part of a link mechanism 16, which will be described later, is fixed with a nut 2o.

Here, the first gear 11a and the second gear 11b are a type of eccentric gear, and their external shapes are determined from the following viewpoints.

That is, first, consider the relationship between the ratio of the angular velocity of the first gear 11a to the angular velocity of the second gear 11b (hereinafter simply referred to as "angular velocity ratio") and the torque transmitted between both gears 11a and llb. As is generally known in gear devices, the angular speed ratio and the transmitted torque are in an inversely proportional relationship. For example, when the angular speed ratio is maximum, the torque transmitted from the first gear 11a to the second gear 11b is the minimum.

On the other hand, in a conventional device in which both gears 11a and llb are circular, the output torque at the motor output shaft of the wiper motor is as shown in FIG. 4B, for example, when the rotation angle of the motor output shaft is approximately 40 degrees and approximately 320 degrees The maximum value is reached at the point of degree. These locations where the torque is maximum correspond to approximately the center of the wiping area. The rotation angle of the first gear 11a that produces such maximum torque is α1. If α2 is assumed, the angular velocity ratio of the gear 118° 11b in the wiper drive device S is set to take the minimum value at al and α2. This is due to α1, which requires a large torque as described above.
This is to enable the largest force to be transmitted from the gear 11a to the gear 11b at α2. And α1. α
The torque gradually decreases before and after 2 (4th B)
(see figure), the angular velocity ratio is made to change approximately sinusoidally.

However, in terms of θ, around 180 degrees (near the upper half rotation position of the wiper 15), the angular velocity ratio is kept constant to avoid fluctuations, although the torque may be small. The pattern of the angular velocity ratio determined based on such a viewpoint is shown by the solid line in FIG. 3A. Then, the first gear 11a and the second
The external shape of gear 1'lb is determined to satisfy the pattern of angular velocity ratio shown by the solid line in FIG. 3A.

Furthermore, in addition to the above-mentioned conditions, the external shapes of the first and second gears 11a and llb are such that the rotation angle θ2 of the second gear 11b corresponds one-to-one to the rotation angle θ1 of the first gear 11a. is determined.

The first and second gears 11a, l determined from such a point of view
The external shape of lb is such that the part where the angular speed ratio is constant is formed from a part of a circular gear, and the part where the angular speed ratio changes in a substantially sinusoidal manner is formed from a part of an elliptical gear.

Next, the connection between the wooden [S] and the wiper 15 will be briefly explained with reference to FIG. ing.

The link mechanism 16 has a well-known configuration used in this type of wiper drive, and includes a crank arm 16a fixed to the output shaft 13 of the device S, and a link rod 1'.
6b and a swing lever 16c. One end 17 of the swing lever 16c is connected to a pivot shaft 18.
One end of a wiper arm 15b is fixed to this pivot shaft 18. Therefore, when the swinging lever 16c swings, the swinging motion is transmitted to the wiper arm 15b via the pivot shaft □18.

The wiper 15 includes a wiper arm 15b and a wiper brake 15a attached to the wiper arm 15b.

In the above configuration, when the wiper motor 1 is started by the illustrated start switch, the rotating shaft 6 of the wiper motor 1
The rotation of a is transmitted to the first gear 11a of the eccentric gear transmission mechanism 3 via the ohmic gear 2, and the first gear 11a rotates counterclockwise, for example, as shown in FIG.

On the other hand, the second gear 11b begins to rotate clockwise (see FIG. 2) as the first gear 11a rotates. This second
Along with the rotation of the gear 11b, the crank arm 16a also starts to rotate, and the wiper arm 15b starts to swing from the lower inverted position in FIG. This will be wiped out.

With the rotation of the first gear 11a as the first rotating body,
The angular speed ratio between the first gear 11a and the second gear 11b is the third
As shown by the solid line in Figure A, in the region where the rotation angle θ□ of the first gear 11 as the first rotating body is 5360 degrees, where OsO4<α3 and α4≦θ, the maximum value β1 is approximately sinusoidal. and the minimum value β3 (β, 〉β
3).

Considering the magnitude of the torque transmitted from the wiper motor 1 to the crank arm 16a in this section of O≦θ, <α3, the torque transmitted to the wiper arm 15b is largest when the angular speed ratio is the minimum value β3.

As a result, when α5≦θ and ≦α6, the substantially sinusoidal torque fluctuations caused by the lever 16c and rod 16b of the wiper link are offset, and wiping is performed with maximum wiping force and at a constant rate. Also, 0kuθ1<α5. α6〈θ1×α7. At α8<θ1<360 degrees, it plays the role of recovering the speed that has been slowed down relative to the conventional perfect circle. That is, the lever ratio of the lever 16c and the rod 16b is increased, and the shape is more sharp than the conventional perfect circle.

Therefore, the number of rotations required for one wipe of the wiper is equivalent to that of a conventional perfect circular motor.

As described above, in this device S, the force transmitted to the crank arm 16a is maximized in the area approximately in the middle of the wiping area, so the force transmitted to the crank arm 16a is Similar to the conventional device (Nippon Denso Publishing, September 15, 1986, issue number 49-035), this device also has the function of improving the transmission torque at the center of the wiping area.

Next, a specific design example of the first and second gears 11a and llb will be shown.

First, as shown in FIG. 1C, the first and second gears 11
The distance between the axes of a and llb is rl, the maximum pitch radius of the first gear 11a is rl, and the maximum pitch radius of the second gear 11b is r2, and the specific design values of ρ, rl, and r2 are An example is shown in Table 1.

Table 1 In addition, in FIG. 1C, the distance from the rotation center C1, C2 of the first and second gears 11a, 11b to the pitch circumference of the parts other than the parts defined by ri and r2 is the axis The respective distances p are determined so as to satisfy the values shown in Table 1. Under these design values, the first gear 1
Rotation angle θ of the second gear 11b with respect to rotation angle θ1 of 1a
2 and the angular velocity ratio have characteristics as shown in FIG. 3B. That is, first, the first and second gears 11a.

The relationship between the rotation angles of gears 11b is shown by a two-dot chain line in FIG. Although the characteristic line indicated by the dotted line in FIG. 3B deviates from the characteristic line in which the rotation angle θ2 of the second gear 11b is the same as the rotation angle of the first gear 11a, it is approximately one-to-one as a whole. It becomes a relationship. Regarding the angular speed ratio, when looking at the relationship with the rotation angle θ1 of the first gear 11a, the angular speed ratio is maximum when the rotation angle θ1 is between 0 and about 120 degrees and between about 240 and 360 degrees. Value 1.160
49 and a minimum value of 0.756611. When the rotation angle θ is between approximately 120 and 240 degrees, the angular velocity ratio is approximately constant at a maximum value of 1.16049.

Under the dimensions and shapes of the first and second gears 11a and lib described above, the rotation angle of the wiper motor 1 is
Looking at the change characteristics of the output torque and the rotational speed at the rotating shaft 6a, first, as shown by the solid line in FIG. 4A, the output torque varies from approximately 40 degrees to approximately 120 degrees and about 240 degrees to about 32 degrees
Between 0 degrees, it becomes a constant value of about 32 kg-cm, and there is no longer a protruding portion of torque as in the conventional case (see Fig. 4A).

On the other hand, as for the rotational speed, as shown by the two-dot chain line in FIG. 4A, in the above-mentioned region where the output torque is approximately constant, the rotational speed is also approximately constant.

The design values of the first and second gears 11a and llb described above are merely examples, and are not limited thereto.
The second gear for the rotation angle of the first gear 11a shown in Figure A
As long as the basic characteristics of the rotation angle relationship of the gear 11b and the angular velocity ratio are satisfied, the same effect can be obtained even with other values.

[Effects of the Invention] Since the present invention is configured as described above, fluctuations in the torque transmitted to the crank arm of the crank mechanism that drives the wiper, especially the protrusion value, are eliminated, and at least the wiping area of the wiper is reduced. Since the torque near the center is approximately constant, it is therefore possible to use a wiper motor with a smaller rating than in the past, which in turn can contribute to reducing the cost of the device.

In addition, in the range where the output torque to the crank arm is constant, the rotation speed of the wiper motor is approximately constant, so the wiper motor does not generate whining noise due to fluctuations in rotation speed, which is the case with conventional wiper motors. This can meet the demand for quieter traffic.

[Brief explanation of the drawing]

FIG. 1A is a plan view including a partial cross section of the wiper drive device according to the present invention, FIG. 1B is a side view including a partial cross section of the same wiper device, and FIG. 1C is a plan view including a partial cross section of the wiper drive device according to the present invention. 2 is a schematic configuration diagram showing an outline of the connection state between the wiper drive device and the wiper, and FIG. 3A is an explanatory diagram for explaining a specific design example of the first gear and the second gear The relationship between the rotation angle of the second gear and the rotation angle of the first gear of the wiper drive device, and the relationship between the rotation angle of the second gear and the first gear
FIG. 3B is a characteristic diagram corresponding to FIG. 3A in a specific design example of the first gear and second gear of the present wiper drive device, and FIG. 4A is a characteristic diagram representing the ratio of the angular velocities of the gears. A characteristic diagram showing the output torque and rotational speed of the wiper motor with respect to the rotation angle of the wiper motor in an example of a single unit design of the first gear and the second gear of the present wiper drive device, and FIG. 4B shows the rotation of the wiper motor in the conventional device. FIG. 3 is a characteristic diagram showing the output torque and rotational speed of the same motor with respect to the angle. DESCRIPTION OF SYMBOLS 1... Wiper motor, 11a... 1st rotating body (1st gear), 11b...
・Second rotating body (second gear), 13...output shaft,
15... Wiper, 15a... Wiper blade, 15b... Wiper arm, 1, 6 a... Crank arm, S... Wiper drive device.

Claims (1)

[Claims] 1. A wiper motor, a first rotating body rotated by the wiper motor, a second rotating body that rotates in conjunction with the first rotating body, and a crank that serves as the rotation center of the second rotating body. an output shaft to which an arm is attached; the first rotating body and the second rotating body are arranged such that the first rotating body has an angular velocity of the first rotating body relative to the angular velocity of the second rotating body; The angular velocity ratio, which is the ratio of angular velocities, is a constant region where the angular velocity ratio is constant at a maximum value during one revolution of the output shaft, and an angular velocity ratio that is substantially sinusoidal on both sides of this constant angular velocity ratio region. What is claimed is: 1. A wiper drive device characterized in that the wiper drive device includes a changing range that changes, and has an outer shape in which a rotation angle of the first rotor and a rotation angle of the second rotor correspond approximately one-to-one.