JPS6390414A - Blower motor control device for automobile air conditioner - Google Patents

Abstract

PURPOSE:To protect a transistor and a motor by fixedly providing a heat sensing body in between a radiating fin for a transistor and an electric conductor, as a part of the circuit of a motor current, and enabling said circuit to be shut off due to the fusion of said heat sensing body. CONSTITUTION:A heat sensing body is formed with a lead-bismuth alloy, while being formed so as to be fused when the temp. of a fin 6 becomes above its allowable temp. In this structure, if a blower is stopped and the temp. of the fin 6 rises above a defined value due to a locked motor, etc. the heat sensing body 5 is fused and separated from between the fin 6 and an electric conductor 4, shutting off the circuit between the fin 6 and the electric conductor 4. Accordingly, even if a short circuit condition takes place due to the overheating of a transistor T1, and the like, a short circuited current will not flow. Thereby, the burning of a motor and a transistor can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a control device for a blower motor for automobile air conditioning, and in particular, when an abnormal situation such as a motor lock occurs, the blower motor control transistor, motor, etc. are damaged or The present invention relates to a blower motor control device equipped with a mechanism for preventing burnout.

[Conventional technology]

When an abnormal situation such as a motor lock occurs in a blower motor for automobile air conditioning, the motor control transistor, which was previously cooled using the blower motor's air blower and heat radiation fins, generates heat and an excessive current flows, causing damage to the transistor. Since the blower motor burns out, various means have been developed to solve this problem.

For example, as disclosed in Japanese Utility Model Application Publication No. 57-197798, a positive characteristic thermistor is inserted into the base of a transistor for controlling a blower motor, and when the transistor reaches a predetermined temperature or higher, the base current and thus the transistor current are changed depending on the characteristics of the thermistor. Other methods have been proposed, such as reducing the amount of heat generated by the transistor to prevent damage to the transistor, and using a temperature fuse to cut off the current when the transistor overheats.

[Problems to be Solved by the Invention] Among the above-mentioned conventional technologies, those that use thermistor characteristics to reduce the transistor base current and eventually the motor current prevent excessive current flowing through the transistor and damage the transistor. However, if a short circuit occurs between the transistor and the collector due to heat generation of the transistor, etc., a short circuit current flows, making it impossible to protect the transistor and the blower motor.

Additionally, those that flow motor current through a transistor through a temperature fuse generally have no capacity to absorb the inrush current of the blower motor or a relatively large motor current, and the circuit may be disconnected more than necessary. Even if something existed that could withstand the long term, it would be difficult to put it into practical use because it would deteriorate over time and have problems with longevity.

The present invention has been made in view of one or more points, and its purpose is to effectively prevent damage and burnout of a blower motor control transistor and the motor, and in particular, to prevent the motor from being damaged or burnt out even when a short circuit occurs between the emitter and collector of the transistor. An object of the present invention is to provide a blower motor control device that can prevent burnout.

[Means for solving problems]

In order to achieve the above object, the present invention provides a blower motor control device comprising a transistor used to control a motor current of an air conditioning blower motor, a heat dissipation fin of the transistor, etc., in which the heat dissipation fin includes:
A heat sensing body is disposed in contact with the heat dissipation fins or via a conductive heat transfer plate, and a conductive plate is disposed opposite to either the heat dissipation fins or the heat transfer plate. The heat sensing body is fixedly interposed between either the fin or the heat transfer plate and the conductive plate, and the conductive plate, the heat sensing body, and the heat dissipation fin or the heat transfer plate form a series circuit, This series circuit is made a part of the motor current circuit, and the heat sensing body is set so that when the heat dissipation fin reaches a predetermined temperature or higher, it melts and falls in the direction of gravity, thereby interrupting the motor current circuit. This is what happens.

[Effect]

According to the present invention having such a configuration, when the transistor overheats and the heat dissipation fin reaches a predetermined temperature or higher due to an abnormal situation such as a motor lock of the blower motor, the heat sensing body senses this and melts the transistor. Then, the motor slips down from between the heat dissipation fin or the heat transfer plate and the conductive plate, and the motor current circuit is interrupted.

Therefore, damage and burnout of transistors, motors, etc. can be prevented, and even if the emitter-collector of the motor current control transistor is short-circuited due to abnormal heat generation of the transistor, the motor current circuit will be prevented due to melting of the heat sensing element. This prevents short-circuit current from flowing and protects equipment such as motors.

Further, the resin part to which the radiation fins are attached is prevented from becoming abnormally overheated, thereby preventing odor and smoke from being generated.

In addition, the heat sensing element interposed between the radiation fin and the conductive plate can have a sufficiently large current-carrying area compared to wires, etc., so it can ensure sufficient capacity to withstand blower motor inrush current and overload current. , it is possible to provide this kind of practical blower motor protection mechanism.

〔Example〕

A first embodiment of the present invention will be described based on FIGS. 1 to 4.

FIG. 1 is a schematic explanatory diagram of this embodiment, and in the figure, 1 is the (+) terminal' of the motor power supply, and 2 is the (-) terminal.

3 is a blower motor, and a conductive plate 4, a heat sensing element 5, and a heat dissipating fin 6 of a transistor are connected in series from a (+) terminal 1 through a blower motor 3 and a motor terminal M.

As will be described later, the conductive plate 4 is placed on a part of the fin 6 via an insulating collar 14, and a heat sensing body 5 having electrical conductivity is interposed between the conductive plate 4 and the fin 6. The sensing body 5 is fixedly disposed in pressure contact with each opposing surface of the conductive plate 4 and the fin 6 under the pressing force of the spring 8 . fin 6
is connected to the collector of the transistor T1 for controlling the blower motor, and the emitter of the transistor T1 is connected to the (-) power supply terminal 2. The base of the transistor T1 is connected to the motor speed command circuit 7 via a resistor R1, and the speed command signal of the command circuit 7 is input to the base of the transistor T1 to control the blower motor current.

A capacitor C and a Zener diode Z are connected between the collector and base of the transistor T1, and the (+) power supply line 1
When a high voltage surge is applied to the transistor T
The collector voltage of transistor T1 is kept constant to prevent the transistor T1 from being destroyed. Furthermore, a resistor R2 is connected between the base and emitter of the transistor Tz to prevent malfunction due to noise entering the base.

Thermal sensor #-5 is made of, for example, a button-bismuth alloy, and is set to melt when the fin 6 reaches a permissible temperature or higher. Therefore, when the blower is stopped due to a motor lock or the like and wind does not hit the fins 6, and the temperature of the radiation fins 6 rises above a predetermined level, the heat sensing body 5 melts and the fins 6
The fin 6 and the conductive plate 4 slide in the direction of gravity, and the connection between the fin 6 and the conductive plate 4 is interrupted. Therefore, even if the transistor T1 becomes short-circuited due to overheating or the like, no short-circuit current will flow, and burnout of the motor can be prevented. Further, even if the motor locks when the Zener diode Z or the capacitor C deteriorates over time and is in a short-circuited state, the motor current is cut off in the same manner as described above to prevent motor burnout.

Next, the specific structure of a blower motor control device incorporating the protection mechanism of the above embodiment will be explained based on FIGS. 2 to 5.

FIG. 2 is a front view of the blower motor control device of this embodiment;
3 is a cross-sectional view taken along the line A-A in FIG. 2, FIG. 4 is a cross-sectional view taken along the line B-B in FIG. 2, and FIG. 5 is a front view showing some of the parts used in this example. It is a diagram.

In FIG. 2, 10 is the command circuit 7 of FIG.
The printed circuit board 10 is arranged on the upper surface of the main body of the fin 6, and the figure shows the state with the printed circuit board 10 removed.

The fin 6 has a fin element 6a on one side as shown in FIG.
. . , and a conductive plate 4 on the other side. A heat sensing element 5, a transistor Tz, a printed circuit board 10, etc. are arranged.

A transistor TI is fixed to the lower side of the fin 6 surface with a screw 17, and the base terminal 11 and emitter terminal 12 of the first transistor Tz are insulated from the fin 6 and attached to the printed circuit board 10.
It is connected to the. In addition to the printed circuit board 1o,
The resistance Rt shown in FIG.

R2, capacitor C, Zener diode Z, external terminal I
B, (-) power supply terminal 2, etc. are connected.

Further, a case 9 made of synthetic resin is fixed to the upper side of the fin 6 surface with an adhesive or the like. The case 9 has screw holes 9a at symmetrical positions as shown in FIG.

9b is disposed, and a space 13 is formed in the central interior 13 in which the heat sensing body 5 slides down and receives it when it begins to melt. Therefore, the rectangular heat sensing body 5 is inserted into the upper part of the space 13 of the case 9 having such a structure so that only a small portion of the heat sensing body 5, which is indicated by the signal G, protrudes from the case 9. Ru. Common holes 9a, 9 of case 9
As shown in FIG. 4, a screw 16 is inserted through the insulating collar 14, a washer 15° and a spring 8, and the screw 16 is screwed onto the fin 6, as shown in FIG. Further, a conductive plate 4 is located between the insulating collar 14 and the case 9, and this conductive plate 4 is connected to the screw 1.
When 6 is tightened, it is pressed toward the heat sensing body 5 by the pressing force of the spring 8, and in this way, the heat sensing body 5 is interposed and fixed in a press-contact state between the conductive plate 4 and the fins 6. Further, a blower motor terminal M is connected to the conductive plate 4.

According to such a structure of the blower motor control device, the circuit configuration shown in FIG. 1 can be adopted.

Furthermore, as described above, the heat sensing body 4 comes into contact with the heat radiation fins 6 and begins to melt when the heat radiation fins 6 rise above a predetermined temperature. The internal space 1 of the case 9 slides down from the heat sensing body 5.
3 and prevents leakage to the outside.

Next, a second embodiment of the present invention will be described based on FIGS. 6 to 10.

FIG. 6 is a front view of the blower motor control device of this embodiment;
7 is a sectional view taken along the line C-C in FIG. 6, FIG. 8 is a sectional view taken along the line D-D in FIG. 6, FIG. 9 is a sectional view taken along the line E-E in FIG. Figure (a) is a front view of the resin parts attached to the radiation fin in this example, and Figure 10 (b) is a partially omitted front view showing the combined state of the conductive plate, heat sensing element, and transistor used in this example. It is a diagram.

In FIG. 6, 20 is a radiation fin, 21 is a (+) power supply terminal, 22 is a (-) power supply terminal, 23 is a signal input terminal, 2
4 is an upper conductive plate, 24' is a lower conductive plate (heat exchanger plate), 25
2 is a heat sensing body, and 26 is a synthetic resin case. The synthetic resin case 26 has a recess 26a formed in the center of the upper part.
A (+) power supply terminal 21 is arranged to protrude to the front, and one end of the upper conductive plate 24 bent in a step shape is located in the recess 2.
6a, and with one end of this upper conductive plate 24 and the base end 21a of the (+) power terminal 21 overlapping, screw 2
8 and is tightened and fixed.

The other end of the lower conductive plate 24 is located at a cutout 26b (see FIG. 10(a)), which is a cutout of a portion of the synthetic resin case 26. Further, a heat sensing body 25 is arranged on the heat radiation fin 20 near the notch 26b with a lower conductive plate 24' interposed therebetween. The heat sensing body 25 is solder-plated in advance, and is bonded to the upper and lower conductive plates 24 and 24' by plating and fixed between the conductive plates 24 and 24'. Lower conductive plate 24'
The other end is a transistor TI fixed on the fin 20.
is connected to the collector 29 of. The synthetic sesame oil case 26 also includes a (-) power terminal 22 and a signal input terminal 23.
A part of the terminals 22 and 23 are placed in a protruding manner, and the remaining parts of the terminals 22 and 23 are buried in the synthetic resin case 26, and as shown in FIG.
The power supply terminal 22 is connected to the emitter terminal 30 of the transistor T1, and the signal input terminal 23 is connected to the base terminal 3 of the transistor T1.
Connected to 1. Protruding portion 26 of synthetic resin case 26
G has a space of constant height H, and transistor T1
A part of the case can be assembled through the space of the protrusion 26C without interfering with each other.

In addition, the synthetic resin case 26. Upper and lower conductive plates 24°24',
For example, the synthetic resin case 26 shown in FIG. 10(a) is assembled at a predetermined position of the radiation fin 2o, and the upper and lower conductive plates 24 and 24' heat sensing shown in FIG. 10(b) are assembled. The solder joint assembly of the body 25 is connected from the heat radiation fin 20 (notch 26b of the synthetic resin case 26) to the synthetic resin case 2.
It is arranged so as to span across the recess 26a of No. 6, and the recess 2
At 6a, attach the (+) power terminal 21 and the upper conductive plate 24 with the screws 28.
Tightening is performed by fixing the lower conductive plate 24' and soldering it to the collector terminal 29 of the transistor TI.

With the above configuration, the (+) power supply terminal 26 having the blower motor (not shown), the electrically conductive plate 24,
The collector terminal 29 of the transistor T1 is connected in series through the heat sensing body 25 and the lower conductive plate 24', and the signal input terminal 23 for inputting the speed command of the blower motor is connected to the base terminal 31 of the transistor T1. -) The power supply terminal 22 is connected to the emitter terminal 30 of the transistor T1, forming a blower motor control circuit similar to the first embodiment. However, in the case of this embodiment, the upper conductive plate 24. The heat sensing element 25 and the lower conductive plate 24' form a part of a series circuit of the motor current circuit. When abnormal heat is generated in the transistor T1 and, in turn, in the fin 20, the heat sensing element 25 melts and slides down, similar to the first embodiment, and the current flow to the blower motor current circuit is cut off, thereby preventing motor burnout and the like. In the embodiment, the means for fixing the upper conductive plate 24 can be constituted by one tightening screw 28 and solder plating bonding of the heat sensing body 25 to the upper conductive plate 24, so the number of tightening screws 28 is changed from that in the first embodiment. can be done less than
In addition, since the upper conductive plate 24 itself exerts a leaf spring function and presses the heat sensing body 25, the solder surface between the heat sensing body 25 and the upper and lower conductive plates 24, 24' when the heat sensing body 25 is in a normal state. Even if the upper and lower conductive plates 24 should come off,
．． A heat sensing body 25 is pressed against each surface of 24', and the heat sensing body 25
can be fixed and held without any trouble, and the contact resistance at this solder surface position can be lowered to maintain a good current conduction state.

〔Effect of the invention〕

As described above, according to the present invention, when the transistor for controlling the blower motor and the heat dissipation fins reach a predetermined temperature or higher due to a motor lock or the like, the motor current circuit is cut off, thereby preventing damage and burnout of the transistor and the blower motor. Even if a transistor or a transistor shorts due to heat generation, it is possible to prevent abnormal situations such as burnout of the motor.

[Brief explanation of the drawing]

1 is a schematic explanatory diagram showing the first embodiment of the present invention;
The figure is a front view showing the apparatus body of the first embodiment, FIG. 3 is a sectional view taken along line A-A in FIG. 2, and FIG. 4 is a cross-sectional view taken along line B--
5 is a front view of the synthetic resin case used in the first embodiment, FIG. 6 is a front view showing the second embodiment of the present invention, and FIG. 7 is a front view of the synthetic resin case used in the first embodiment. 8th cross-sectional view along line C-C of
The figure is a sectional view taken along the line D-D in Fig. 6, and Fig. 9 is a sectional view taken along line E in Fig. 6.
10(a) is a front view of the resin case used in the second embodiment, and FIG. 10(b) is a sectional view taken along line -E. FIG. 7 is a front view showing an assembled state of the upper and lower conductive plates and the heat sensing body used in the second embodiment. 3... Blower motor, 4, 24... Conductive plate (upper conductive plate), 5, 25... Heat sensing element, 6, 20... Heat dissipation fin, 7... Motor speed command circuit, 8...・・Spring,
9゜26... Synthetic resin case, 14... Insulating collar, 24' Conductive heat transfer plate (lower conductive plate), Tz... 1゛/ Part 3 q - Kazuichi Imaki #Blade case name 4 figure heat 5 figure 6i27 2θ -4 mine quin Z5 - Kiyuki Tomoki 2≦--Ikima aruko! 2wo b case No. 7521 Kuzuq compilation lO diagram

Claims (1)

[Claims] 1. In a blower motor control device comprising a transistor used to control a motor current of an air conditioning blower motor, a heat radiation fin for the transistor, and the like, the heat radiation fin includes a heat radiation fin. A heat sensing body is disposed in contact with or via a conductive heat transfer plate, and a conductive plate is disposed opposite to either the heat dissipation fins or the heat transfer plate. The heat sensing body is fixedly interposed between one of the plates and the conductive plate, and the conductive plate, the heat sensing body, and the heat radiation fin or the heat transfer plate constitute a series circuit, and this series circuit is connected to the conductive plate. In addition to being part of the motor current circuit, the heat sensing body is configured so that when the heat dissipation fin reaches a predetermined temperature or higher, it melts and falls in the direction of gravity to interrupt the motor current circuit. A control device for a blower motor for automobile air conditioning. 2. In claim 1, the heat sensing body comprises:
A control device for a blower motor for an automobile air conditioner, which is fixedly interposed between the conductive plate and the heat dissipation fin by pressing the conductive plate disposed on the heat dissipation fin with a spring. 3. In claim 1, the heat sensing body comprises:
A control device for a blower motor for an automobile air conditioner, which is fixedly interposed between a conductive plate disposed on the heat radiation fin and the heat transfer plate by soldering. 4. The control device for a blower motor for an automobile air conditioner according to claim 1, wherein the heat dissipating fins include a case that catches the heat sensing body when the heat sensing body melts and falls.