JPS58173318A - Timer for oven - Google Patents

Abstract

PURPOSE:To determine the preheating time, in which a mechanical type timer serving as the switch is still ON, in accordance with the initial temperature within an oven by providing a mechanical type timer which controls the baking time of the oven and a CR timer circuit which controls the preheating time, and simulating the discharge property of the capacitor of said CR timer circuit to the discharge property within the oven after turning OFF of the power source. CONSTITUTION:The timer 1 uses a spring 3 mounted on an operating shaft 2 as a driving source, and the templet 6 of an escapement 5 provided through a gear system 4 is vibrated and driven for a predetermined period. When the operating shaft 2 is wound up toward a direction indicated by arrow (a) in the drawing to set a time, a cam 7 mounted on the operating shaft 2 turns ON a switch 8 and the spring 3 is wound up, whereby the templet 6 is driven toward a direction indicated by the arrow (b), and a time switch 8 is turned OFF after lapse of a set time and a beat ball 9 beats a bell to report the finish of cooking. On the other hand, a relay 11 has a movable contact 13 fitted to a movable piece 12, an (a) side contact 14 which makes contact with said movable contact 13 by driving the relay 11, and a (b) side contact 15 which makes contact therewith when the relay is turned OFF. An engaging member 16 is mounted on the movable piece 12. Said engaging member 16 controls the templet 6 of the above timer 1 when the relay 11 is driven to stop the timer 1. When the relay 11 is turned OFF, the control is removed to start the timer 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oven timer that preheats the oven for a time determined depending on the initial temperature inside the oven and then controls the roasting time.

Conventionally, oven timers have been used such as the so-called wind-up timer, which uses a spring as the driving source, and the so-called motor-type timer, which uses a small synchronous motor as the driving source.
Both methods simply control the roasting time depending on the type of food, and the temperature inside the oven varies depending on whether the oven is cold or hot, that is, when it is used once and then used again. Since the temperatures vary widely, there is a drawback in that simply setting the roasting time according to the type of food will result in large changes in the outcome of the food.

In particular, when trying to make toast in a toaster oven, the above-mentioned drawbacks become noticeable because the roasting time is extremely short, 3 to 4 minutes compared to other types of cooking. When roasting, roasting is done for the same amount of time, such as the first roasting and the second roasting, or the second roasting after a short time after the first roasting. Even when toasting is performed, the initial temperature inside the oven causes a large difference in the toasted texture of the toast, and the time must be set extremely precisely each time roasting is performed, which is extremely inconvenient.

For this reason, attempts have been made to control the operating time of the timer by detecting the initial temperature inside the oven with a temperature sensing element such as a bimetal or thermistor. It is difficult to make the heat radiation follow the heat dissipation inside the oven, and the device becomes large and expensive, making it impractical.

This invention was made in view of the above points, and includes a mechanical timer that controls the roasting time of the oven and a CR timer circuit that controls the preheating time. An oven timer that eliminates the drawbacks of the conventional oven by approximating the heat dissipation characteristics of the later oven interior and determining the preheating time during which the mechanical timer waits with the switch on depending on the initial temperature inside the oven. Embodiments of the present invention will be described below with reference to the drawings.

1 to 4 show a first embodiment of the present invention, in which a timer (1) uses a mainspring (3) attached to an operating shaft (2) as a driving source, and is driven by a gear system (4). The device drives the main shaft (6) of the escapement (5) provided in
When the time is set by winding the clock in the direction indicated by the arrow, the cam (7) attached to the operating shaft (2) turns on the time switch (8) and winds up the mainspring (3), which drives the clock in the direction indicated by the arrow. After the set time has elapsed, the time switch (8) is turned off and the striking ball (9) strikes the bell (II) to notify the completion of the cooking. When the time switch (8) is restrained, the time switch (8) is restrained.
) can be turned on and the timer operation can be stopped, and the force that restrains the Obu (6) may be extremely small.

On the other hand, relay 0υ is a b-side contact that comes into contact when the movable contact 03 attached to the movable piece (2) and relay 0υ are driven to turn off the movable contact (a-side contact 0x and relay 01 that contact 13). α9, and a locking piece OQ is attached to the movable piece q, and the locking piece αQ is connected to the relay (1
When υ is driven by 1, the Obu (6) of the timer (1) is restrained to stop the timer (1), and when the relay OD is turned off, the restraint is released and the timer (1) is started. There is.

Next, FIG. 3 is an electrical circuit diagram, in which AC power (E) is supplied to the oven heater (H) via the time switch (8) of the timer (1), and the diode (DI)
), a resistor (R1), a capacitor (C1), and a Zener diode (ZDI). The CR timer circuit consists of a CR time constant circuit consisting of a variable resistor (VR) and a capacitor (C2) connected to a DC power supply, a feedback resistor ( It consists of a Schmitt trigger circuit in which the input resistor (R2) is connected in parallel and the input resistor (R3) is connected in series.
1) The movable contact (11 has a capacitor (C2), the a side contact 04) has a variable resistor (VR) and an input resistor (R3)
The connection point is the discharge resistor (R4) at the b side contact α.
are connected to the discharge resistor (R4), and a Zener diode (Zn2) is connected in parallel to the discharge resistor (R4), and is connected to the DC power supply circuit via the reverse current prevention diode (D2) and the current limiting resistor (R5). The discharge circuit is always maintained at a constant voltage value as long as DC power is supplied. Further, the output of the CR timer circuit is connected to an inverter (INT
3), and the transistor (
A relay 0]) is connected to the collector of the transistor (TR), and a relay 0]) is connected to the collector of the transistor (TR).
When TR) is turned on, relay 01) is driven, and the output side of the inverter (INT4) is connected to the base of the transistor (TR) via a backflow prevention diode (D3) and a resistor (R7). The inverter (INT4) and the capacitor (C3) constitute a cent circuit when the power is turned on, the resistors (R8) and (R9) are current limiting resistors, and the resistor (RIO) is the capacitor (C3).
This is the initial setting resistance.

Therefore, when the timer (1) is set for a time corresponding to the type of food, the time switch (8) is turned on, the heater (H) is energized, and the inverter (INT4) of the setting circuit generates a short pulse. The transistor (
TR) is turned on and the relay is energized, so that the capacitor (C2) is connected to the charging circuit side, and the locking piece 00 restrains the Obu (6) to put the timer (1) in a standby state. Also, by connecting the capacitor (C2), the output of the Schmitt trigger circuit becomes rLOWJ, the output of the inverter (INT3) becomes rHIGHJ, and the relay 0
Preheating is started by maintaining the energization in step 1). Then, while the capacitor (C2) is gradually being charged, when the voltage value exceeds the threshold of the inverter (INTI), the Schmitt trigger circuit is inverted and the transistor (T
R) is turned off, so the relay (1υ is turned off and the locking piece O
Q releases the restraint of Obu (6), so the timer (1)
starts, the preheating time ends, and the roasting time starts.Also, the capacitor (C2) is connected to the discharge circuit side, but is maintained at a constant voltage value by the Zener diode (Zn2).

When the roasting time set by the timer (1) is over, the time switch (8) is turned off and the bell 01 rings to notify the completion of the cooking, and the supply of DC power is also stopped. (C2) starts discharging only through the discharging resistor (R4).

By the way, the discharge characteristic of the capacitor (C2) shows a curve similar to the heat dissipation characteristic inside the oven as shown in Fig. 3, so the Zener voltage of the Zener diode (Zn2) and the discharge resistor (R4) By appropriately setting the resistance value, it is possible to make the two very similar. Therefore, as shown in Figure 4, it is possible to calculate how much time (x) has passed since the oven heater was turned off. The operating time (T) of the CR timer circuit, that is, the preheating time, can be automatically determined by using the button 1.This makes it possible to preheat according to the initial temperature inside the oven. Just by setting the roasting time with a single touch, you can always cook perfectly.

In this first embodiment, the top (6) of the timer (1) is restrained by a locking piece QQ provided on the relay Q], but in addition to this, the top is made of a magnetic material or a magnet, It can also be restrained by the magnetic force generated when the relay is activated.

Next, FIG. 5 is an electric circuit diagram showing a second embodiment of the present invention, in which a small synchronous motor (
Using a motor-type timer with M) as the driving source, relay (
1) In addition to the changeover switch, there is a timer control switch a.
motor (M) while relay 0υ is on.
The other configurations and effects are the same as those of the first embodiment, and the preheating time can be easily controlled even when a motor-type timer is used.

As described above, the present invention includes a mechanical timer having a time switch for controlling the roasting time of the oven, a CR timer circuit for controlling the preheating time of the oven, and a mechanical timer driven by the output of the CR timer circuit. and an f-relay having a changeover switch that controls the start of the CR timer circuit and switches the capacitor for setting the time constant of the CR timer circuit between the charging circuit side and the discharging circuit side. By approximating the release time of the time constant setting capacitor, the mechanical timer determines the preheating time for waiting with the time switch turned on depending on the initial temperature inside the open refrigerator. This allows the operator to simply set the roasting time according to the type of food, and the oven will automatically preheat according to its initial temperature and then roast before adding it to the food. The amount of heat is always constant, which has the effect of allowing extremely uniform roasting.

In addition, the mechanical timer uses the conventional spring-type timer or motor-type timer as is, and CR
It is extremely practical as it only requires the addition of a timer circuit and relay.

Furthermore, the configuration is extremely simple, and the CR timer circuit in particular can use a general-purpose IC that integrates a large number of gate circuits, so it has the advantage of being able to be provided at a much lower price than other methods that use temperature control. .

[BRIEF DESCRIPTION OF THE DRAWINGS] The drawings show an embodiment of the present invention. Fig. 1 is a front view of the first embodiment, Fig. 2 is an electric circuit diagram, and Fig. 3 shows heat dissipation characteristics in an open refrigerator. 4 is a graph showing the characteristics of preheating time, and FIG. 5 is an electric circuit diagram showing the second embodiment. (1)...-Timer (6)...Obu (7) Kai...Cam (8)...Time switch (1)
υ...Relay 0su...Movable piece (13...
Movable contact 04)...A side contact flFll...
b 11111 contact uQ...locking piece Uη...
Timer control switch (E)...AC power supply (H)...Heater (jv[
)...Motor (INTI~4) -...Inverter (TR)...Transistor (ZDI~2)・e・Zener diode (D1~3)
11e11 diode (ci~3)... capacitor

Claims (1)

[Scope of Claims] 1. A mechanical timer having a time switch that controls the open roasting time, a CR timer circuit that controls the open preheating time, and a mechanical timer driven by the output of the CR timer circuit. and a relay having a changeover switch that controls the start of the CR timer circuit and switches the time constant setting capacitor of the CR timer circuit between the charging circuit side and the discharging circuit side, and the heat dissipation characteristics inside the oven after the power is turned off. By approximating the discharge characteristics of the time constant setting capacitor, the preheating time during which the mechanical timer waits with the time switch turned on is determined according to the initial temperature in the open refrigerator. Oven timer 〇2. Claim 1, characterized in that a CR timer circuit for controlling open preheating time is constituted by a resistor and a capacitor for setting a time constant, and a Schmitt trigger circuit.
3. The mechanical timer is a spring-type timer that uses a mainspring as a driving source and operates at a constant speed by the action of an escapement, and by restraining the crown of the escapement, the mechanical timer is The oven timer according to claim 1 or 2, characterized in that the oven is in a standby state. 4. The mechanical timer is a motor-type timer whose driving source is a small motor, and the mechanical timer is put into a standby state by turning off the power of the small motor with a timer control switch provided in a relay. An oven timer according to claim 1 or 2.