JPS6336250B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a vacuum cleaner that effectively cools semiconductor devices.

Conventional Technology In recent years, vacuum cleaners with power consumption control devices have been commercialized from the perspective of energy conservation. Semiconductor devices such as three-terminal controlled rectifiers have come into use. In addition, magnetic relays were conventionally used to turn on and off the power by remote control, but due to problems such as dust getting into the contacts and poor durability, semiconductor relays were considered and put into practical use. It has been. When using such a semiconductor device in a vacuum cleaner, the most important thing to consider is how to prevent the semiconductor device from overheating. Needless to say, semiconductor devices have the characteristic of generating self-heating when current flows through them, and if this exceeds an upper limit, they will be destroyed. Especially in vacuum cleaners, electric blowers generate self-heating. When the exhaust gas temperature increases and the amount of air flowing in decreases due to clogging of the filter device, the temperature of the exhaust passage itself sometimes approaches the upper limit of the temperature of the semiconductor element. For this reason, in the past, a heat sink to which the semiconductor element was fixed was provided, and this heat sink was placed in a compartment that was isolated from the exhaust passage of the main body and communicated with the atmosphere, and this compartment was further communicated with the intake side of the front of the electric blower. A method was adopted in which cooling air was always sucked in from the atmosphere when the electric blower was rotating.

However, with the above-mentioned means, there is always an airflow that bypasses the filter device, which leads to a decrease in suction performance.

In addition, instead of guiding the air sucked by the electric blower into a compartment, the compartment was opened to the atmosphere, and in addition, a ventilated opening facing the exhaust path of the electric blower was formed in a part of the compartment. (Jikko 49-
Publication No. 31017).

Problems to be Solved by the Invention The pressure in the opening of the ventilate is low due to the effect of the exhaust flow (ventilic effect), and therefore the atmosphere is sucked into the compartment and cools the heat sink.

However, a fatal drawback of this cooling means is that when the filter device becomes clogged, the amount of air flowing through the compartment is reduced. That is,
If the intake flow rate of the electric blower decreases due to clogging of the filter device, the exhaust flow rate of the electric blower will naturally decrease as well. As is well known, the Ventilly effect changes in proportion to the flow rate, and therefore, the above-mentioned means cannot always reliably cool the heat sink.

The present invention solves these conventional problems and aims to accurately cool a semiconductor element at any time.

Means for Solving the Problems As shown in FIG. 5, the present invention incorporates an electric blower 4 and forms an exhaust passage 7 that communicates the electric blower 4 with an exhaust hole for discharging the exhaust flow a to the outside air. a main body, an exhaust passage 7 and a partition wall 31 of the main body.
A compartment 30 with a ventilation hole 26 that communicates with the outside air is connected to a negative pressure section at the front of the electric blower, and a pressure difference between this negative pressure section and the outside air is established. The device is equipped with a safety valve device 20 that opens and introduces outside air, and a metal heat sink 28 to which a current control semiconductor element 29 is fixed, which is provided across both the compartment 30 and the exhaust passage 7. be.

According to the present invention, when the filter device etc. are in a normal state and the safety valve device 20 is closed, the heat sink 28 is sufficiently cooled by the exhaust flow of the electric blower 4, and the filter device etc. are in a normal state and the safety valve device 20 is closed. When clogging occurs and the safety valve device 20 opens, the heat sink 28 is reliably cooled by the atmosphere b flowing into the compartment.

Example Examples thereof will be described below with reference to the accompanying drawings.

In the figure, 1 is a main body roughly divided into left and right sides,
Inside, an electric blower 4 held by a front support 2 and a rear support 3, and a winding device 6 for a power cord 5 are installed. Reference numeral 7 denotes an exhaust passage formed by an outer wall 8 and an inner wall 9 of the main body 1, through which exhaust air flows from an electric blower chamber 10 to an exhaust chamber 11, and is discharged to the outside air via an exhaust gasket 12 and an exhaust hole 13. Reference numeral 14 denotes a dust collection box that can be attached to and detached from the main body 1 using a buckle device 15, and has a filter device 16 inside it that can be attached and detached. 1 to form a negative pressure section 18. Reference numeral 19 denotes a handle formed integrally with the main body 1, and a pressure-type safety valve device 20 that operates when the suction power is lower than the maximum air volume and introduces outside air is installed inside. This safety valve device 20 includes a connecting pipe 21 that communicates with the negative pressure section 18, and a connecting pipe 21 that communicates with the negative pressure section 18.
A substantially cylindrical transparent valve cylinder 25 which has one end fitted into the valve body and has a valve spring 22 and a valve body 23 therein, and a valve hole 24 having an inner diameter smaller than the outer diameter of the valve body 23 at the other end. The valve element 23 is slidable within the valve cylinder 25 and is biased toward the valve hole 24 by a valve spring 22. 26 is a ventilation hole formed in the handle 19, through which outside air is introduced and introduced into the safety valve device 20.
27 is an open display window through which the movement of the valve body 23 can be confirmed through the transparent valve barrel 25. Reference numeral 28 denotes a metal heat sink to which a bidirectional three-terminal control rectifier element 29 (hereinafter referred to as a semiconductor element), which is a semiconductor element, is fixed with screws or the like, and a compartment 3 is formed at the rear of the handle 19.
0, and the compartment 30 and exhaust passage 7.
The heat sink 28 is sandwiched between left and right partition walls 31 of the main body 1, and a portion of the heat sink 28 projects into the exhaust passage 7. Reference numeral 32 denotes a printed circuit board incorporating a control circuit, which is held by a rib body 33 of the main body 1.

Next, the electric circuit will be briefly explained based on FIG. The printed circuit board 32 includes a trigger element 34 for sending a signal to the semiconductor element 29 fixed to the heat sink 28, and a variable resistor 35, a resistor 36, and a capacitor 37 for adjusting the signal current of the trigger element 34. A control circuit that controls the current flowing through the electric blower 4 and changes the rotation speed of the electric blower 4 is incorporated. A capacitor 38 and a resistor 39 are a protection circuit for the semiconductor element 29, and a hand switch 40 for remote control is also provided.
A current is caused to flow through the control circuit by turning on and off.
In addition, the current flowing through the auxiliary bidirectional three-terminal control rectifier element 41 (hereinafter referred to as auxiliary semiconductor element), the trigger element 42 that sends a signal to this auxiliary semiconductor element 41, the capacitor 43, and the hand switch 40 is converted into a minute current. A resistor 44 is provided. In the above circuit, when the hand switch 40 is turned on after applying voltage to the power source, the capacitance is stored in the capacitor 43, and when the voltage reaches a certain level, a signal is sent from the trigger element 42 to the auxiliary semiconductor element 41.
A current is passed through. Then, current flows into the control circuit by the auxiliary semiconductor element 41, and the capacitor 38
When a certain capacity is accumulated, a signal is sent from the trigger element 34 to the semiconductor element 29, current flows through the main circuit, and the electric blower 4 rotates. This semiconductor element 2
9 causes a self-heating effect when a large current flows, and if it exceeds a certain limit, the junction part inside the semiconductor element 29 is destroyed, so the heat sink 28
It must be kept constantly cooled. The maximum junction temperature of the semiconductor element 29 used in this embodiment is 125°C, and in this case, the junction case temperature Tj (hereinafter Tj
) has set the upper limit at 75℃. When the hand switch 40 is turned off, the auxiliary semiconductor element 41 no longer conducts current, so the current also stops in the main circuit, and the electric blower 4 stops.

In the above configuration, when the electric blower 4 rotates, the exhaust air flows through the exhaust passage 7, but if the filter device 16 is not clogged and there is sufficient air flow, the electric blower 4 is also cooled. , the temperature of the exhaust stream does not rise much,
The heat sink 28 protruding into the exhaust passage 7 is cooled to prevent the temperature of the semiconductor element 29 from rising excessively, but if the filter device 16 becomes clogged and the electric blower 4 is insufficiently cooled, the temperature of the exhaust passage 7 will drop. However, in this embodiment, the air volume at the tip of the hose extension pipe is 0.7.
m ³ /min, the pressure in the negative pressure section 18 becomes lower than the outside pressure, and pressure acts on the valve body 23 of the safety valve device 20 through the valve hole 24, causing the valve spring 2
2, the valve body 23 moves in the direction of the connecting pipe 21, and outside air flows into the negative pressure section 18 through the ventilation hole 26 and the valve hole 23, so the semiconductor element 29 is cooled by the outside air and is prevented from overtemperature. Prevent rising.

To explain about FIG. 4, it is a graph depicting how the temperature changes, and the curve shows the safety valve operation when the heat sink 28 with the semiconductor element 29 is installed in the compartment inside the main body 1. This shows the change in temperature rise at the immediately preceding air volume.As the exhaust passage temperature rises, the cooling effect worsens, and Tj
The upper limit has been exceeded. The curve shows the change in air volume immediately before the safety valve operates when all the heat sinks 28 with semiconductor elements 29 are stored in the compartment 30 of the handle 19.
Since it is isolated by the air and is in contact with the outside air, it has a certain cooling effect and does not exceed the Tj upper limit, but if the safety valve device 20 does not operate and the air volume further decreases, the temperature in the exhaust passage 7 will rise. Therefore, a safety valve device 20 is provided to prevent the temperature from rising by introducing cooling air when the air volume falls below a certain level. Of course, from the above,
If the heat dissipation plate 28 is completely separated from the exhaust passage 7 and other places where the temperature rises, the safety valve device 20 is unnecessary, but in this case, the main body 1 becomes large. Next, to explain the curve, the curve is the temperature change when the heat sink 28 is projected into the exhaust passage 7 as shown in FIG. 1, and the curve is the temperature change in the open air volume when the filter device 16 is not clogged. , is the temperature change when the air volume is just before the operation of the safety valve device 20 (approximately 0.7 m ³ /min in this example). As the air volume decreases, the temperature rise increases, and the cooling effect of the heat sink 28 decreases. However, when the air volume is sufficient (close to the open air volume), the heat sink 28 is cooled by the exhaust flow to prevent the temperature from rising. Immediately before the safety valve device 20 operates,
Although the effect of the heat radiating plate 28 protruding into the exhaust passage 7 disappears, when the air volume decreases slightly below this level, the safety valve device 20 is activated and cooling air flows through the compartment 30 of the handle 19 to cool the semiconductor element 29. Therefore, since the temperature rise value is lower than that of the curve, it is possible to use the semiconductor element 29 with a lower upper limit of Tj.

Effects of the Invention As described above, according to the present invention, when there is a large exhaust flow, the semiconductor elements installed on the heat sink can be cooled by the heat dissipation effect of the heat sink because the partition wall and the exhaust passage are separated from each other by the partition wall. If the exhaust gas temperature rises and the temperature in the compartment begins to rise due to a decrease in the air flow due to a clogged filter, etc., the safety valve device will operate to reduce the outside air flow. Since it flows into the compartment, it is possible to achieve a sufficient cooling effect on the semiconductor elements. In addition, the safety valve device reduces the air volume,
Since it operates when the suction becomes poor, the suction performance does not deteriorate during normal cleaning, allowing efficient cleaning. Note that, if the air volume at this time is set to be lower than the air volume at which the suction power has the highest value, normal suction performance will not be affected.

[Brief explanation of the drawing]

Fig. 1 is a front view showing the overall structure of a vacuum cleaner according to an embodiment of the present invention in partial cross section, Fig. 2 is a cross-sectional view taken along the line A-A in Fig. The electric circuit diagram adopted in the example, FIG. 4 is a temperature characteristic diagram showing the effects of this embodiment, and FIG. 5 is a schematic configuration diagram of the present invention. 1...Main body, 4...Electric blower, 7...Exhaust passage, 18...Negative pressure section, 20...Safety valve device, 28
... Heat sink, 29 ... Semiconductor element, 30 ... Compartment.

Claims (1)

[Claims] 1. A main body with a built-in electric blower and an exhaust passage that communicates the electric blower with an exhaust hole for discharging exhaust air to the outside air, and a main body that is separated by a partition wall from the exhaust passage of the main body and communicates with the outside air. a safety valve device that communicates a compartment provided with a ventilation hole with a negative pressure section at the front of the electric blower and opens and introduces outside air due to a pressure difference between the negative pressure section and the outside air; A vacuum cleaner equipped with a metal heat sink to which a current control semiconductor element is fixed, which is provided astride both a compartment and an exhaust passage.