JPS6120993B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface heating method, which is used for snow melting and freezing prevention in road heating, roof heating, etc.

When heating road surfaces or roof surfaces to melt snow or prevent freezing, heating wire circuits are installed on these surfaces, and when the surface temperature reaches the lower limit set temperature, the heating wire circuit is energized, and the heat generated by the electricity is used to heat the heating wire circuits. When the surface temperature reaches the upper limit set temperature, the above-mentioned energization is cut off, and after this energization is cut off, when the surface temperature falls to the lower limit set temperature again, the power is turned on again, and the above-mentioned cutoff and energization can be repeated from then on. be.

In this case, the surface to be heated may be divided into several areas, a heating wire circuit may be installed in each area, and each area may be electrically heated under independent control.

In this current heating method, the heating line circuits in each area are parallel to each other, and the power source for these circuits is common.

This energization heating method has the advantage that even if a failure such as a disconnection occurs in the heating line circuit in one area, heating in other areas is not affected and heating in other areas can be continued.

However, this current heating method, that is, the parallel heating wire circuit method, as with the series heating wire circuit method, requires a large load current and requires large-scale equipment for supplying power supply current. That is, since the state of temperature change in each zone is substantially the same, the heating line circuits in each zone are energized at substantially the same period. Therefore, if the current flowing through the heating line circuit in each zone is I, power supply equipment with a current capacity of NI (where N is the number of zones) is required.

In view of the above-mentioned points, the present invention reduces the current capacity required for power supply equipment, thereby making it possible to downsize the power supply equipment, or making it possible to use existing power supply equipment without restrictions in terms of current capacity. A surface heating method is provided. That is, in the surface heating method according to the present invention, the surface to be heated is divided into n areas, and the first, second,...
......The n-th heating wire circuits are each installed, and when the surface to be heated reaches the lower limit set temperature, a preliminary heating current is applied to all the heating wire circuits, and after the current is applied, it is immediately added to the first heating wire circuit. A heating current is supplied to heat the first zone to the upper limit set temperature, and immediately after this heating, supply of additional heating current to the first heating wire circuit is cut off, and additional heating is performed to the second heating wire circuit. Electric current is supplied to heat the second zone to the upper limit set temperature, and thereafter,
After selecting the 3rd, 4th, ... nth zone as described above, heating each zone in that selection order to the upper limit setting temperature, and heating the nth zone to the upper limit setting temperature, , immediately cut off the supply of additional heating current to the n-th heating line circuit and supply additional heating current to the first heating line circuit to heat the first area to the upper limit set temperature, and thereafter, the above-mentioned A method characterized by repeatedly selecting the second, third, etc. areas in this manner and heating each area in the selected order to the upper limit set temperature using an additional heating current. It is.

The present invention will be explained below with reference to the drawings.

In FIG. 1, A is the heated surface where snow melting and freezing prevention should be performed, and n areas, for example, three areas A ₁ to
It is divided into A ₃ areas, and heating line circuits C ₁ to C ₃ are installed in each area. These heating line circuits are configured to have the same current flow and the same amount of heat generated per unit area.

Now, when the temperature of the heated surface A reaches the lower limit set temperature (freezing temperature), the preheating current _I1 is applied to all the heating wire circuits _C1 to _C3 . The temperature of the heated surface A under this preheating current _I1 does not reach the upper limit set temperature (ice melting temperature). After the preliminary heating current is applied, the additional heating current I ₂ is supplied to the first heating line circuit C ₁ , and a current of I ₁ +I ₂ =Io is applied to the circuit.

Each of the heating line circuits described above is composed of several circuits, and the current flowing from I ₁ to I ₁ +I ₂ can be changed by switching the several circuits from series connection to parallel connection, or from △ connection to Y connection. ,It can be carried out.

By supplying the current I ₁ + I ₂ to the first heating line circuit C ₁ , the current in the first heating line circuit C ₁ is changed to I ₁ as soon as the temperature in the first area A ₁ reaches the upper limit temperature setting. At the same time, the current flowing through the second heating line circuit C ₂ is set to I ₁ +I ₂ . Due to the current I ₁ + I ₂ to the second heating line circuit C ₂ ,
As soon as the temperature in the second area _A2 reaches the upper limit set temperature, the current in the second heating line circuit _C2 is changed to _I1 , and the current in the third heating line circuit _C3 is increased to _I1 + _I2 . be done.
As soon as the temperature in the third area A ₃ reaches the upper limit set temperature by the current I ₁ + _{I 2 to} the third heating line circuit C 3 , the current in the third heating line circuit C ₃ is changed to I ₁ and again. The above-mentioned additional heating current _I2 is supplied to the first heating line circuit _C1 , and the current of the first heating line circuit _C1 is changed from _I1 to _I1 + _I2 .

After that, the above process is repeated.

The surface heating method according to the present invention is as described above, and the current supplied from the power source is (n-1)I ₁ + (I ₁
+I ₂ ) or nI ₁ +I ₂ (n is the number of areas on the heated surface)
It is. On the other hand, the conventional method of individually and independently controlling the energization of each heating line circuit requires a power supply current of nI ₁ +nI ₂ .

Therefore, the present invention has the advantage that the power supply equipment can be made small-scale or that there are fewer restrictions on the use of the power supply in terms of current capacity. Furthermore, although the electric heating load for each heating area differs depending on the amount of snowfall, etc., the temperature of each area can be calculated by combining the freezing temperature T _L and the ice melting temperature T _H , regardless of the snowfall amount or freezing state. Freezing can be reliably prevented since the temperature can be maintained at a temperature between Also, since preheating current is constantly flowing through each area, even if the heating rate of the additional current is not very rapid, it will not cause much of a traffic problem (sleet conditions will continue for a long time, but freezing will occur). (If you don't have one, you can avoid problems such as slips), and you can use a smaller power source.

FIG. 2 shows a switching control circuit between heating line circuits used in the present invention.

In Figure 2, Tc ₁ to Tc ₃ are the first to third areas.
Tc ₁ ′ to Tc ₃ ′ indicate the opening/closing contacts of the temperature regulators Tc ₁ to Tc ₃ , respectively. M ₁ to _{M 3} are electromagnetic switches for the first to third heating wire circuits, M ₁ ′ to _{M 3} ′ are b contacts for the electromagnetic switches M ₁ to M ₃ , T ₁ to _{T 3} are timers, T ₁ ′ to T ₃ ′ is a timer contact, TF is a timer, and TF′ is a timer contact.

In FIG. 2, when a voltage is applied to input terminal R-S, switches S ₁ and S ₂ are automatically turned on. Now, when the temperature of the heated surface reaches the lower limit set temperature, the temperature regulators Tc ₁ to Tc ₃ are activated, and the contacts Tc ₁ ′ to
Tc ₃ ′ is turned on and timers T ₁ to _{T 3} are activated. The setting time of timers T ₁ to _{T 3} is timer T ₁ ,
The timer contact T 1 ′ is set to be long enough to reach T ₂ and T ₃ , and the timer contact T ₁ ′ is turned on. This timer contact
The ON operation of T ₁ ′ operates the electromagnetic switch M ₁ and opens the b contact M ₂ ′M ₃ ′. Therefore, electromagnetic switches M ₂ and M ₃ are not activated.

When the temperature in the first zone reaches the upper limit set temperature, the contact Tc ₁ ' of the temperature regulator Tc ₁ is turned off, and the electromagnetic switch M ₁ is cut off. At the same time, the b contact M ₁ ' is turned on. In this state, the temperatures in the second zone and the third zone are below the upper limit set temperature, and the contacts Tc ₂ ' and Tc _{3 '} of the temperature regulators Tc ₂ and Tc ₃ are turned on. Therefore, timer T ₂ as well as
T ₃ operates, but since the set time of timer T ₂ is shorter than the set time of timer T ₃ , the electromagnetic switch is turned on by turning on contact T ₂ ′.
M ₂ is activated, and b contact M ₂ ' is turned off. Therefore, electromagnetic switches M ₁ and M ₃ do not operate.

When the temperature in the second zone reaches the upper limit set temperature, the contact Tc ₂ ' of the temperature regulator Tc ₂ is turned off, and the electromagnetic switch M ₂ is cut off. At the same time, b contact M ₂ ' is turned on. Due to the OFF operation of the above contact Tc ₂ ',
Timer TF is activated and timer contact TF' is turned off. Therefore, among the timers T ₁ and T ₃ for the electromagnetic switches M ₁ and M ₃ , voltage is not applied to the timer T ₁ because the contact TF' is off, and the timer T ₃
is activated, and timer contact T ₃ ' is turned on. Therefore, the electromagnetic switch M ₃ is activated, and the b contact M ₃ ' is turned off. Timer contact TF′ is this b contact
It is turned on immediately after M ₃ ' is turned off.

When the temperature in the third zone reaches the upper limit set temperature, the contact Tc ₃ ' of the temperature controller Tc ₃ is turned off, and the electromagnetic switch is turned off.
_M3 is blocked. At the same time, b contact M ₃ ' is turned on. In this case, the contacts Tc ₁ ′ and Tc ₃ ′ are on because the temperatures in the first and second zones have fallen below the upper limit set temperature, and therefore the timers T ₁ and T ₂
is energized. However, since the set time of timer _T1 is shorter than the set time of timer _T2 , timer contact _T1 ' is turned on and electromagnetic switch _M1 is activated. At the same time, the b contact
M ₁ ′ is turned off and electromagnetic switch M ₂ is not activated.

Thereafter, the operations of the electromagnetic switches M ₂ −M ₃ −M _{1 .} . . are repeated in the same manner as above.

FIG. 3 shows the heating wire circuit used in the present invention, and when the electromagnetic switches Mo ₁ to _{Mo 3} are turned on, the power supply voltage is applied to the first to third heating wire circuits C ₁ to _{C 3} .
RST is energized. When the electromagnetic switches M ₁ to _{M 3} are off, each heating line circuit C ₁ to _{C 3} is connected in series or in the Δ connection as described above. When the electromagnetic switches M ₁ to M ₃ are turned on, the heating line circuits C ₁ to _{C 3} are switched from the series connection to the parallel connection, or from the Δ connection to the Y connection.

FIG. 4 is a control circuit for the electromagnetic switches M ₁ to M 3 and Mo ₁ to Mo ₃ for the heating line circuit in FIG. ₃ . The control circuit of FIG. 4 is different from the control circuit of FIG. 2 described above in that contacts Tc ₁ ′ to Tc ₃ ′ are also inserted on the side of the electromagnetic switches Mo ₁ to _{Mo 3} . Additionally, manual contacts H ₁ to _{H 3}
is added.

In FIG _. 4, _the contact points Tc ₁ ′ to Tc ₃ ′ are as described above, because during heating of the surface to be heated, any area will always be below the set upper limit temperature. is in the on state. Therefore, the electromagnetic switch Mo ₁ ~
Mo ₃ is in an on state, and in this state, the above-described current I ₁ is applied to the first to third heating line circuits C ₁ to _{C 3} in FIG. 3. And electromagnetic switch M ₁ ~
As mentioned above, M ₃ is in the order of M ₁ → M ₂ → M ₃ → M ₁ , and only one of M ₁ to M ₃ is heated as described above for the period until the heating area reaches the set upper limit temperature. I ₁ + I ₂
current is supplied. That is, by switching the connection in the heating line circuit as described above, the conducting current is increased from I ₁ to I ₁ +I ₂ .

The circuits shown in FIGS. 2 and 3 described above are a series of circuits used to implement the present invention, and the present invention can be implemented with circuits other than those described above.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram to show the present invention, Fig. 2 is a circuit diagram showing a switching circuit of a heat generating line circuit used in the present invention, and Fig. 3 is a circuit diagram showing a heat generating line circuit used in the present invention. 4 are circuit diagrams showing the operation circuit of the electromagnetic switch shown in FIG. 3. In the figure, A is the surface to be heated, A ₁ to _{A 3} are the first to
The third area, _C1 to _C3 , are the first to third heating line circuits.

Claims (1)

[Claims] 1 Divide the surface to be heated into n areas, and divide the first, second,... nth areas into the first, second,...
... Each n-th heating wire circuit is laid, and when the surface to be heated reaches the lower limit set temperature, a preliminary heating current is applied to all the heating wire circuits, and immediately after the current is applied, additional heating is applied to the first heating wire circuit. Electric current is supplied to heat the first area to the upper limit set temperature, and immediately after this heating, supply of additional heating current to the first heating wire circuit is cut off, and additional heating is performed to the second heating wire circuit. Electric current is supplied to heat the second zone to the upper limit set temperature, and thereafter,
After selecting the 3rd, 4th, . Then, the supply of additional heating current to the n-th heating line circuit is cut off, and the additional heating current is supplied to the first heating line circuit to heat the first area to the upper limit set temperature, and thereafter, as described above. te second, third,
......A surface heating method characterized by repeatedly selecting areas and heating each area in the selected order to an upper limit set temperature with an additional heating current.