JPH0437803Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention is a burnout prevention device for automobile wiper motors using a circuit breaker, and in particular promotes heat dissipation of the circuit breaker and improves the performance of the wiper motor under high loads. Concerning what you do.

[Prior Art] A wiper motor for an automobile may be subjected to a high load depending on its usage conditions, and it is necessary to provide a burnout prevention device. This burnout prevention device is housed within the main body of the wiper motor.

Here, an example of a conventional burnout device for a wiper motor for an automobile will be explained based on FIGS. 6 and 7. FIG. 6 shows the overall configuration of this conventional device, and FIG. 7 shows a cross section of its main parts. A stator 120 is fixed to the inner peripheral surface of the yoke 110 of the main body 100. and,
A rotor 130 is rotatably supported inside the stator 120 and opposite thereto. A gear housing 140 is provided at one end of the main body 100, and includes a screw shaft 150 which is an output shaft from the rotor 130 and a gear 1 meshed with the screw shaft 150.
60 are accommodated. A disk-shaped brush holder 170 is fixed to the connection portion between the yoke 110 and the gear housing 140. On the rotor 130 side surface of this brush holder 170, a brush (not shown) and a breaker holder 180 are fixed. A circuit breaker 200 is housed inside this breaker holder 180. Note that a portion of the breaker holder 180 protrudes into the gear housing 140 through an opening provided in the brush holder 170.

Next, the operation of this conventional example will be explained. When the wiper motor is energized, the screw shaft 150 is rotated together with the rotor 130. Then, the gear 160 meshed with the screw shaft 150 rotates, and this rotation drives the wiper. When the load on the wiper becomes high and the load on the wiper motor becomes high, a large current flows through the circuit breaker 200.
Circuit breaker 200 is opened and current is interrupted. The circuit breaker 200 is cooled by cutting off the current, and is automatically reset when the circuit breaker 200 is sufficiently cooled.

Although the structure of the circuit breaker, which is a feature of this invention, is not shown, the overall structure of the wiper motor for automobiles is based on the U.S. Pat.
78263, Utility Model Application No. 57-78264, Utility Model Application No. 57-45457, etc.

[Problem that the invention aims to solve] Circuit breakers operate by generating heat according to the amount of current flowing through them, so they are easily affected by the surrounding temperature, and if the motor is generating heat, The circuit breaker will operate more easily.
If the activation of the circuit breaker is delayed in an attempt to avoid this, once the circuit breaker is activated, it will take a long time to recover, and the current will remain cut off for a long time. Therefore, when the wiper is under a high load, the time during which the wiper motor can be continuously operated becomes very short, and the wiper cannot be operated satisfactorily.

Furthermore, by adjusting the resistivity of the circuit breaker, the time it takes for the circuit breaker to open for a given current can be changed, but it is not possible to shorten the release time alone; The problem could not be resolved.

Further, in the conventional configuration, the breaker holder needs to be fixed to the brush holder by screwing or the like, and there is a problem that assembly is troublesome.

This idea was developed to solve these conventional problems.It allows the desired current to be cut off during high loads, and also ensures that the wiper is fully activated even during high load operation in order to restore the current in a short time. An object of the present invention is to provide a burnout protection device for an automobile wiper motor that can ensure a long operating time.

[Means for solving the problem] The burnout prevention device for an automobile wiper motor of this invention is housed inside the main body of a wiper motor that drives the wiper of an automobile, and includes a gear housing provided at one end of the main body, and a gear housing provided at one end of the main body. A circuit breaker that is housed in the housing and cuts off the current to the wiper motor when the amount of current to the wiper motor exceeds a predetermined amount; and a circuit breaker that houses the circuit breaker and has a protruding stopper on the back side. a breaker holder, and a plate spring fixed within the gear housing so as to press and fix the circuit breaker against the inner surface of the gear housing, and having an opening or a recess that fits into the protruding stopper. The inside of the gear housing is partitioned from the inside of the housing by a brush holder, and the brush holder has a notch on its periphery, and the breaker holder housing the circuit breaker can be separated from the inside of the gear housing by the notch. It is characterized by being inserted into.

[Function] When the load on the wiper of the automobile is large, the load on the wiper motor also becomes large, and the amount of current flowing to the motor increases. When the increase in the amount of current reaches a predetermined amount, a circuit breaker operates to cut off the current. As a result, the current flowing to the motor through the circuit breaker is cut off, and the rotation of the motor is also stopped. The motor and circuit breaker are cooled by natural heat radiation.
When the temperature of the circuit breaker has dropped sufficiently, the circuit breaker is reset and power supply to the motor is resumed. In this way, burnout of the motor is prevented.

In the burnout prevention device for an automobile wiper motor of this invention, the circuit breaker body is pressed against the inner surface of the gear housing by a leaf spring. Therefore, the heat dissipation characteristics of the circuit breaker body are significantly improved. In other words, the heat of the circuit breaker is transferred to the gear housing and is radiated from there. Therefore, the amount of current that the circuit breaker uses to interrupt the current can be increased, and the continuous operation time under high load can be extended. When the amount of current reaches a predetermined limit value, the circuit breaker is activated and cuts off the current.
At this time as well, cooling of the circuit breaker is promoted by this heat dissipation, and the time required for the circuit breaker to recover can be significantly shortened.

In this way, the desired heat dissipation characteristics can be achieved by the very simple method of pressing and fixing the circuit breaker against the inner surface of the gear housing using the leaf spring. Thereby, the current can be cut off at a predetermined high current value, and the recovery time once the circuit breaker is activated can be significantly shortened. Therefore, while the function of preventing burnout of the motor is reliably performed, the operating time of the motor during high-load operation can be significantly increased.

In addition, in the present invention, the breaker holder is
A protruding stopper is provided on the back side to accommodate the circuit breaker and fit into an opening or recess formed in the leaf spring, and the brush holder has a notch on the periphery, so the circuit breaker can be stored in the circuit breaker. Easy installation and positioning can be achieved by inserting the breaker holder containing the kit breaker through the notch in the brush holder and fitting the stopper of the breaker holder into the opening or recess formed in the leaf spring. .

[Embodiment] A burnout prevention device for an automobile wiper motor according to an embodiment of this invention will be described with reference to FIGS. 1 to 4. FIG. Here, Fig. 1 is a sectional view of the main parts, Fig. 2 is a sectional view of the wiper motor as seen from the rotor side to the gear housing side, Fig. 3 is a perspective view of the breaker holder, and Fig. 4 is a perspective view of the leaf spring. It is. Note that FIG. 1 is a sectional view taken along line AA in FIG. 2.

Yoke 1 in which the main body of the wiper motor is housed
A gear housing 12 is fixedly connected to one end of the 0. Here, this gear housing 12 is formed of aluminum die-casting. A disc-shaped brush holder 14 is screwed to the gear housing 12. Three brushes 16 are fixed to this brush holder 14. A notch 14a is formed in a part of the brush holder 14,
A circuit breaker 20 housed in a breaker holder 18 is inserted here. Note that the brush holder 14 is made of an insulator such as glass-filled phenolic resin.

Here, as shown in FIG.
The lower member 18a of No. 8 has a box shape with an open front side, and the upper member 18b has an elongated plate shape with a diamond shape when viewed from the side. A pair of receiving plates 18c are provided on the back surface of the lower member 18a, and a stopper 18d is formed on the back surface near the connecting portion between the lower member 18a and the upper member 18b. A circuit breaker is housed within this breaker holder 18. In addition, breaker holder 1
8 is made of synthetic resin.

The circuit breaker 20 has a circuit portion covered with a metal case, and cords 22 from the two brushes 16 are connected to the circuit breaker 20. gear housing 12
There are protrusions 12b on both sides of the breaker accommodating part 12a.
is formed. Both ends of a plate spring 24 made of stainless steel are inserted and fixed into the protrusion 12b, respectively. This leaf spring 24 is elastically deformed toward the center when the breaker holder 18 is housed, and in this state, the receiving plate 18
By pressing c, the breaker holder 18
is pressed toward the inner surface of the gear housing 12.
Here, since the front surface of the circuit breaker 20 protrudes from the breaker holder 18, the circuit breaker 20 is directly pressed against the inner surface of the gear housing 12. And circuit breaker 20
The front surface is flat and rectangular. Also,
A breaker accommodating portion 12a of the gear housing 12 into which the circuit breaker 20 is inserted has a pair of guide strips 12 that guide the circuit breaker 20.
c is formed to match the width of the circuit breaker 20, and in order to make surface contact with the front surface of the circuit breaker 20, it is formed not into a curved surface but into a flat surface. In addition, when the front surface of the circuit breaker 20 is a curved surface, the inner surface of the gear housing 12 may be the same curved surface. As a result, the entire front surface of the circuit breaker 20 comes into contact with the inner surface of the gear housing 12.

Further, as shown in FIG. 4, the plate spring 24 has an opening 24 in which a stopper 18d is fitted to position the breaker holder 18 when the breaker holder 18 is inserted.
a is formed. As a result, when assembling, simply inserting the breaker holder 18 into the breaker accommodating portion 12a of the gear housing 12 with the circuit breaker 20 accommodated, the breaker holder 1
8 can be fixed in place. Here, the opening 24a may be replaced with a recess. Further, the brush 16 is in contact with a commutator 28 attached to the output shaft 26 to supply current. In addition, circuit breaker 20, breaker holder 1
The overall structure other than the mounting structure 8 is the same as that of the conventional example shown in FIG.

Next, the operation of the apparatus of this embodiment will be explained. When operating the wiper of an automobile, current is passed through the wiper motor through the circuit breaker 20, the brush 16, and the commutator 28, and the output shaft 26 is rotated. This rotation of the output shaft 26 drives a wiper (not shown).

Here, when the load on the wiper motor increases and the amount of current increases, the circuit breaker 2
Heat generation within 0 also increases. When the temperature inside the circuit breaker 20 reaches a certain level or higher, the circuit breaker 20 is activated and the current passing therethrough is cut off. When the current is cut off, heat generation within the circuit breaker 20 stops, and the temperature of the circuit breaker 20 decreases due to heat radiation. here,
Since the front surface of the circuit breaker 20 is in surface contact with the aluminum gear housing 12, heat radiation occurs due to good heat transfer, and the circuit breaker 2
The temperature of 0 rises slowly during heat generation and quickly falls during cooling.

Figures 5A and 5B show the results of a comparative experiment between an embodiment of this invention and a conventional example. This experiment investigated the time it takes for the circuit breaker to open for the first time and the time it takes for the circuit breaker to return for the first time when the same high current is applied to the embodiment of this invention and the embodiment of this invention. As is clear from this, the initial opening time is longer in the embodiment of this invention at both room temperature and high temperature. In addition, the initial recovery time is shorter in the embodiment of this invention, and the reduction is particularly significant at high temperatures.

As described above, according to the configuration of this invention, it is possible to delay the time until the circuit breaker opens, to lengthen the continuous operation time of the wiper motor under high load, and to significantly shorten the recovery time of the circuit breaker 20. I understand. Therefore, according to the device of this embodiment, the circuit breaker is activated as late as possible to prevent burnout of the motor, and the continuous operation time of the motor can be significantly extended while maintaining the function of preventing burnout. . Furthermore, even if the circuit breaker is tripped, the recovery time can be greatly reduced.
Operation downtime can also be extremely shortened.

Further, according to this embodiment, the following effects can also be obtained.

Since the gear housing is made of aluminum, it has good heat conduction and the heat dissipation effect of the circuit breaker is good.

The brush holder is made of glass-filled phenolic resin, which has poor thermal conductivity, so it can block the heat of the motor and has a good heat dissipation effect.

Since the surface of the gear housing that contacts the circuit breaker is made flat so that the circuit breaker and the inner surface of the gear housing can come into surface contact, the heat dissipation effect is good.

Since the circuit breaker is inserted through a notch provided in the brush holder, assembly is very easy.

Since an opening is provided in the leaf spring so that the stopper of the breaker holder engages with the opening, it is very easy to insert and position the breaker holder.

Since a pair of guide strips are provided in the circuit breaker accommodating portion of the gear housing, insertion of the breaker holder is ensured and rocking of the circuit breaker is also prevented.

[Effects] As described above, according to the burnout prevention device for automobile wiper motors of this invention, the time until the circuit breaker is activated can be made longer, so the continuous operation time of the wiper motor under high load can be significantly reduced. Furthermore, even if the load increases and the circuit breaker is tripped, the recovery time is significantly shortened, so the downtime can be minimized. As a result, it is possible to utilize the capability of the wiper motor to the maximum extent while ensuring the function of preventing burnout of the wiper motor.

In addition, the brush holder has a notch on its periphery, and the breaker holder containing the circuit breaker can be inserted through the notch, making assembly easy. Since it fits into the opening or recess, positioning can be easily performed.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view showing a main part of an embodiment of the burnout prevention device for an automobile wiper motor according to this invention, and FIG. 2 is a sectional view taken in a plane perpendicular to the output shaft of this embodiment. FIG. 3 is a perspective view of the breaker holder of this embodiment, FIG. 4 is a perspective view of the leaf spring of this embodiment, and FIG. 5 is a diagram showing the results of a comparative experiment between this embodiment and a conventional example. FIG. 6 is a partial sectional view showing the overall configuration of a conventional wiper motor, and FIG. 7 is a partial sectional view showing the main parts of this conventional example. 12... Gear housing, 14... Brush holder, 18... Breaker holder, 18a... Stopper, 20... Circuit breaker, 24... Leaf spring.

Claims (1)

[Scope of Claim for Utility Model Registration] A burnout prevention device for a wiper motor housed inside the body of a wiper motor that drives wipers of an automobile, comprising a gear housing provided at one end of the body, and a gear housing housed within the gear housing. , a circuit breaker that cuts off the current to the wiper motor when the amount of current to the wiper motor exceeds a predetermined amount, and a breaker holder that houses the circuit breaker and has a protruding stopper on the back side. , a leaf spring fixed within the gear housing so as to press and fix the circuit breaker against the inner surface of the gear housing, and having an opening or a recess that fits into the protruding stopper; is partitioned from the inside of the housing by a brush holder, the brush holder has a notch on its periphery, and the breaker holder housing the circuit breaker is inserted into the gear housing through the notch. A burnout prevention device for an automobile wiper motor, which is characterized by: