GB2230534A

GB2230534A - The control device for an electric oil press

Info

Publication number: GB2230534A
Application number: GB9006506A
Authority: GB
Inventors: Chun-Ho Ma
Original assignee: MA CHUN HO
Current assignee: MA CHUN HO
Priority date: 1989-03-27
Filing date: 1990-03-23
Publication date: 1990-10-24
Anticipated expiration: 2010-03-23
Also published as: FR2644730B1; JPH07122070B2; SE9000971D0; IT9019842A0; IT9019842A1; IT1239420B; KR900013907A; JPH0372599A; GB2230534B; DE4009654C2; NL9000726A; CH683079A5; KR910004251B1; FR2644730A1; GB9006506D0; SE9000971L; DE4009654A1

Abstract

The invention relates to a control device for a domestic oil press. The invention comprises a means for detecting whether the sesame or other seed is or is not fed into the press; a means for detecting the temperature of a cylinder; a means for heating a cylinder; a means for switching power of motor on or off; and a microprocessor for controlling all these means. The invention increases the yield as well as the quality of oil by securing the proper temperatures of the cylinder and at the same time prevents the motor from being overloaded and prevents the feeding inlet from becoming blocked.

Description

1 THE CONTROL DEVICE FOR AN ELECTRIC OIL PRESS BACKCROUND OF INVENTION

1. Field of Invention

The present invention relates to a microproc-essing control device used in domestic electric oil presses.

2. Description of Prior Art

Conventional electric oil presses for domestic use are generally constituted of a motor shaft, a revolving shaft which, geared to the motor shaft, has a spiral screw formed around its tapering body for conveyance of sesame or other seed and is fixed inside a cylinder; a hopper with its outlet for material for pressing attached to the inlet of the conveyance screw of the revolving shaft; an outlet for pressed oil fixed below at one side and another outlet for the hulls below at another side; heaters fixed on the inside of the cylinder to heat sesame or other seed for efficient pressing of oil; and an oil 20 container for receiving the pressed oil attached to the outlet of the cylinder and another receptacle for the receiving hulls attached to the hulls-outlet.

When the properly parched sesame is put in the hopper and power is switched on the motor is set in 25 motion as the heater starts heating, and by the motion 2 of the motor the sesame moves down along the curves of the conveyance screw, and is pressed in the cylinder.

But in such conventional presses, when the switch is turned on, both the heater and the motor begin operation simulatanously, resulting in commencement of pressing oil before the cylinder is sufficiently preheated. Thus at a lower than adequate temperature the sesame, hulls, and pressed oil together become coagulated and stick onto the screw blades, often causing an overload on the motor. An overload can stop the motor. Not only can the process of pressing oil be interrupted but an overcurrent can flow to the motor. If these irregularities are left undetected, they can burn up the motor and cause serious damage to the press.

Another problem for conventional domestic oil presses is the lack of a device to monitor the temperature inside the cylinder and control the supply of power to the heater in order to adjust it at the correct temperature. When the temperature inside the cylinder becomes lower or higher than needed while the press is in operation, the yield of pressed oil decreases. And in worse cases, if the temperature inside the cylinder becomes extremely lower than needed, the overloading, and the flow of an overcurrent as stated above, can ensue to damage of the motor, and when the temperature becomes extremely 3 higher than needed, it can scorch the sesame, resulting in a yield of oil of inferior quality. Moreover, an overheating of the cylinder can at times reach the inlet for feeding the sesame -thereby causing evaporation of moisture of the sesame still deposited in the inlet area, causing the sesame to coagulate and to block the inlet itself. Yet anothera problem with the conventional press is the lack of a device that provides constant supervision over the entire operation of the press. Lack of such a device results in a failure to shut off the power switch fast enough at the completion of a pressing operation and causes both the heater and the motor to stay on resulting in not only a waste of power but also in a possible breakdown of the 15 press caused from overheating of the heater.

SUMMARY OF INVENTION

The primary objective of the present invention is to provide a control device for regulating operation of domestic electric oil presses. This control device increases the yield of oil and raises the oil's quality by securing proper temperatures of the cylinder when the press is originally turned on and maintains proper temperatures throughout the operation. In addition, the control device prevents the overloading of the motor and the blocking of the feeding inlet.

4 A Another objective of the present invention is to provide a control device for domestic electric oil presses with a regulatory -circuit system which, instantly detects an overcurrent flow to the motor, and cuts power off from the heater.

Yet another objective of the present invention is to provide a control device for domestic electric oil presses which regulates the press to adapt automatically to either 10Ov or 2 20v power depending on the need of the outlet.

To attain these main objectives the control device of the present invention has, as its special features, a means of detecting whether sesame or other seed to be pressed has yet been fed into the press; a means of detecting the temperature inside the cylinder; a means of heating the cylinder; a means of switching the power on and off; a microprocessor connected to each of the above means, which, by regulating the output of the means of detecting the feeding of sesame and the temperature, generates the output signals for cotrol of the corresponding means of heating and the means of switching the power for the motor.

The control device of the present invention begins to work immediately after the press is switched on. When the press is switched on the program stored in the microprocessor activates the feeding-detection means to determine whether sesame has been fed into the hopper. If the sesame is not fed into the hopper, the motor simply does nothing. The moment the ses.ame is fed into the hopper, the microprocessor activates the heating means to preheat the cylinder to a temperature proper for pressing the sesame. The temperature inside the cylinder is constantly monitored by the temperature-detecting means. As soon as the preheating of the cylinder is completed the microprocessor activates the motor through the power-switching means, and the pressing of oil begins.

While the pressing of oil continues the microprocessor monitors the temperature inside the. cylinder through the detection means to determine whether the proper temperatures are maintained, while regulating the operation of the heating means to secure the proper temperature at all times.

Thus, the best suitable temperature is secured inside the cylinder at the beginning, and during the-operation. Therefore, the yield of oil is increased and its quality excellent. Undesirable stoppages of the motor or blocking of the feeding inlet does not occur.

The microprocessor also monitors whether or not sesame is fed into the press and therefore knows when the hopper is empty. But, only when the pressing of oil is completely finished (the last of the sesame 6 in the cylinder has been pressed and the last of the hulls are eliminated from the cylinder) is the power automatically shut off from both the motor. and the heater. Power is saved.

In the present invention, the microprocessor has other circuits connected to it as well. One of which is a trigger synchronizing circuit, another distinguishes the need of 10Ov and 220v power, and yet another shifts the taps of the motor at need.

By means of the second circuit mentioned above, before the oil-pressing operation begins it is immediately distinguished whether the power in supply is 10Ov or 220v. Then by means of the motor-tap shifting circuit the taps are shifted. The heating 15 means supplies power for all cycles when power is at 10Ov and supplies power for only one of each five cycles when the power is at 22Ov. Thus the objectives of the present invention are better attained.

By means of the trigger synchronizing circuit, the trigger point of the heating means is synchronized to the power voltage at the voltage's zero cross point. Owing to the programming of the microprocessor in such a way that all these functions are performed automatically, it is possible to use the 25 oil press regardless of whether the power is at 10Ov or 220v. Thus the objectives of the present invention are better attained.

7 The microprocessor also has a circuit for detecting a flow of overcurrent through the motor. If an overcurrent through the motor is detected, the microprocessor immediately halts, by its built-in power-switching means, stopping the operation of both the motor and the heating means, and thus can automatically stop the press itself in the event of a malfunction thereby eliminating the possibility of serious damage to the press. Thus the objectives of the present invention are better attained.

In the present invention, the press includes both the means of monitoring temperatures and the means of switching the motor to a circuit for raising the preheating temperature. Therefore, the temperature inside the cylinder at conclusion of the preheating will rise higher than the proper temperature of the cylinder during the oil-pressing operation, thus the load at the begining of oper'ation of the press will get much lighter, facilitating the starting of the press itself, whereby the objectives of the present invention are to be better attained.

Moreover, in the present invention, the press is also equipped with a circuit which indicates each state of operation the press is in such as the waiting, 26 preheating, in operation, occurrences of irregularities, the voltage power at each moment, etc. Therefore it is possible to view every state that the press is in at 8 each moment to attain the objectives of the present invention for further satisfaction..

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 is a front view including a partial sectional view of an embodiment in accordance with the present invention.

Fig. 2 is a drawing showing a demonstration of the control device of the present invention.

Fig. 3 is a flow chart showing the process of control of an oil press with the device of the present invention.

DETAILED DESCRIPTION OF INVENTION

Referring now to Fig. 1 and Fig. 2, the circuit (150) is for monitoring whether or not sesame has been fed into the press to include a serial circuit of a resistor (R5) and LED (D11) and a bridge circuit of resistors (R6,R7,R8) and a photodiode (D12). The output of the bridge circuit is connected to the microprocessor (U.S. National, COM 420L) through the IC(ICI). The LED device (D11) and the photodiode (D12) are fixed at the feeding inlet (121) to function in a way, in which, when the sesame has been poured in the inlet (121), the light from LED (D11) will be blocked to shut the diode (D12) off.

The circuit (151) for detecting the temperature of the cylinder includes a bridge circuit of resistors (R1,R2,R3) and the thermister (Thl) 9 connecting its output to the input terminal of the comparator IC (IC2), and the output of the IC(IC2) to the microprocessor (153), while the thermiste.r (Thl) is inserted in the pressing cylinder with grooves.

Accordingly, when the temperature in the cylinder (117) rises to the predetermined temperature, the output from the comparator IC(IC2) outputs power at the low level, namely 0 and when the temperature in the cylinder (117) falls below the predetermined temperature, it outputs at its high level namely 1.

The circuit (152) for heating the oilpressing cylinder (117) is designed to have the triac (TRAIC1) connected to the heater (M), to the gate of the triac (TRIACI) connected to the source (YDD) of the direct current through a transistor (Q1) and over a (R9), and to the base of the transistor (Q throurh the resistor (R,9), to resistor connected microprocessor (153); and t around the beater (H0 on its outside. Thereupon, in accordance with the signal given forth to the microprocessor (153) the trigger on the traics is controlled.

The motor-switching circuit (154) for switching on and off the power source for the motor (M) has a triac (TRIAC2) connected to the power cable, its gate connected to the source (YDD) of the direct voltage through a transistor (Q4) and a resistor (R20) the he cylinder (117) is coiled and at the same time the base of the transistor (Q4) to the microprocessor(153) over a resistor (R19); the trigger of the triac (TRIAC2) is to be cont.relled by the signals given forth to the microprocessor (153).

And in order that the oil press can operate with either 10Ov or 220v power there are three separate circuits provided; a circuit (158) for detecting the voltage at either 10Ov or 220v, a trigger-synchronizing circuit (159) for triggering the heating circuit (152) at its zero-cross point, and a tap-shifting circuit (155) for shifting the 10Ov/22Ov taps.

The circuit(158) for detectin& the voltage of the power includes a serial circuit of resistors (R11, R13) connected to power source(VA) on the input side of the circult(CVC) which generates a constant direct voltage; serial circuit of resistors(R12, R14) connected the output side of the circult(CVC): IC(IC3) for comparator whose input terminal is connected to the respective contact point of resistors(R11, R13) and resistors(R12, R14), and output terminal is connected to the micro processor(153).

This device enables the direct voltage (M) to stay constant when the voltage of the power source is 10Ov or 220v, but when the voltage of the power source is 220v, the direct voltage (VA) is twice as high as when it is 10Ov. Therefore, the output of the comparator IC (IC3) varies according to the values of 11 the power voltage such as at 22Ov it is 1 and at 10Ov it is 0.

In the trigger synchronizing circuit (159), a collector and emitter of transistor(Q2) are connected to the microprocessor and the earth, respectively, and the transistor (Q2) base is connected to the power source through the condenser(C1) and resistor(R21); Therefore, the circuit (159) transmits a synchronizing signal on the microprocessor at each cycle of the voltage. Then the circuit (155), for shifting of the taps, is connected to the relay (Ry) for shifting to and from the tap for exclusively 10Ov (connected at the contact point B of the relay) and the tap for exclusively for 220v (connected at the contact point A of the ralay). One terminal (H) of the relay (Ry) is connected to the earth through transistor (Q3) and the other terminal (CC) of the relay (Ry) is connected to the power source, the base of the transistor (Q3) is connected to the microprocessor(153) through a resistor (R22).

Also provided is Circuit (157) for detecting an overcurrent to the motor (M) in the event of an irregularity in the oil-pressing process, and is made up in the form of shaping a close circuit on the line supplying the power by means of connecting a detection coil (L), which monitors an induction current to a diode (D10), and a condenser (C3): and by forming a 12 bridge circuit of the resistor (R18) connected in a series onto the condenser(C2) and other resistors (R15, R16, R17), with the output connected to the input terminal of the comparator IC (IC4) and the output of this IC (IC4) to pin 22 of the microprocessor (153); whereby, in the event that an overcurrent flows to the motor (M), a current corresponding to it is detected by the induction coil (LI) and charges the condenser (C3) through a diode (D10), so the IC (IC4) is caused to generate an output 1.

Also provided is, an indication circuit (16) for indicating which of the various stages the oilpress is at by indicating the IOOV voltage by LED (D4), the 220v voltage by LED (D5), the state of preheatin- by LED (D6), the operating state by LED (D7), the waiting state by LED (D8) and the detection of an irregularity of the press by LED (D9).

A circuit (161), consisting of resistor (RIO) and diode (D20) is provided to raise the preheating temperature only during the beginning of the oilpressing operation which is a higher temperature setting than the temperature setting needed for remaining operating period, and is connected between the temperature detection circuit (151) and the power switching circuit (154).

Moreover, circuit (156) is provided for indicating whether or not the oil container (113) and is the hulls receptacle container (114) are duly inserted in their designated places, with the circuit(156) magnet switch (MSW) connected between the mi.croproces sor and the earth, so that the switch will turn off the moment the oil container and the hulls receptacle container are inserted in their places.

And of those unexplained in the above; 164 is a widely known constant power voltage circuit; 162 is the pulse generator for supplying pulse to the microprocessor (153), 163 is the microprocessor (153) resetting circuit, 111 is a worm, 112 is a worm gear, 119 is the conveyance screw, 115 is the outlet for the pressed oil, and 116 is the outlet for the hulls.

Now the function of the control device of the present invention for domestic electric oil presses, consist of the system shown above and is explained with reference to Figs. 1 and 2 along with the flow chart showing the operation of the control device at each of its stages.

When the power is switched on and the micorprocessor (153) is set in motion, the microprocessor (153), according to the program stored in it, remembers mode 3 and makes its pin 26 generate 0, whereby the LED (D3) of the indication circuit (160) 125 operates to indicate the state of waiting. It is then determined, by pin 23, whether the output of the circuit (158) for detecting the power voltage is 1.

14 If it is 1 (as it should be when the voltage is 220v) the output at both pins 12 and 17 becomes 1 respectively, whence the LED (D4) of the indication circuit (160) and the transistor (Q2) of the circuit (155) for shifting the taps are set in motion, while the 220v is indicated and the tap exclusively for 220v power of the motor (M) is connected. However, if it is determined by pin 23 that the output of power is not 1, as it should not be if it is 10Ov, then 1 is indicated at pin 12 and 0 at pin 17 to show that the power is 10Ov, while at the same time the transistor (Q3) on the tap-shifting circuit (155) is turned off and the motor (M) is shifted to the tap exclusively for use of 100Y power.

Then it is determined whether the input at pin 21 is 1, (it should be 1 because the magnetic switch (Msw) is turned off when the oil container and the hulls receptacle container are both inserted) and if it is not 1 yet, mode 3 is memorized and, by getting pin 17 to generate an output 0, the tap is shifted back to that for exclusive use of 10Ov; and after setting the LED (D8) (the element for indicating the state of waiting), the procedure stated above for determining the voltage of power by pin 23 is repeated until the output at the pin 21 becomes 1 with the insertion of the oil container and the hulls receptacle container.

As soon as the output at pin 21 reads 1, and since mode 3 is remembered on the program the mode is selected and the microprocessor (153) starts operating with mode 3 (B of Fig. 2).

In the process of mode 3 it is whether the input at pin 5 reads 1 or not. If at this time the sesame is fed into the inlet (121), the photodiode (D12) turns off, as stated above, and the IC (IC1) is 0, while, if the the photodiode (D12) will the comparator IC (IC1) is the sesame has not been fed into the inlet process described so far repeats itself input at pin 5 reads 0.

the input at pin 5 reads instead of mode 3; pin 0 and pin 1 outputs 1, setting, LED (D6) in operation to begin preheating the cylinder. Then through the process of determining the states of pins 23 and 21, mode 1 is selected (as mode 1 was momorized immediately before).

In mode 1 (C of Fig. 3) it is determined whether the input at pin 5 reads 1 and, if it is not (in the case of 1 the process stated above repeats itself), it is then determined whether the input at pin 6 reads 1 [because the cylinder (117) has not yet been prehea-ted at this stage, the value of the resistance on the thermistor (Thl) rises greatly, the output of the comparator sesame has not yet been fed 10 remain on and the output of 1. So while (121), the until the sesame is fed and the But when the sesame is fed and 0, the program remembers mode 1 23 outputs determined is output at the IC (IC2) coming to 1, and the input at pin 6 also is 11, and if it indeed reads 1, the process moves onto the heating state of the heater (H0 through the route of -the TEC in mode 2 (D of Fig. 3). Then it is determined whether the input at pin 23 reads 1 not. [As it has been said above, the output (IC3) is 1 when the power is 22Ov, and it is 0 power is 100v]. When it is determined to be oil-pressing cylinder (117) is having pulses generated a 5th at pin 14 and as their synchronizing circuit (1 (TRIACI) of the heating eircul each five cycles of the power trigger the triac (TRIAC1) at 1 if it is determined, instead, pulses are generated at pin (TRIAC1) ( also a t cycles of the repetition until completed.

or o f IC when the 1, the preheated by means of frequencies divided in with the trigger- trigger the tralc for only one of and also getting it to ts zero-cross point; and to be 0, then 14 to trigger synchronized 59) so as to t (152) undivided the triac its zero-cross point) for all the power; This process continues in the preheating of the cylinder is When the preheating is completed, the ohmic value of the thermistor (Thl) of the temperature detecting circuit (151) falls below the prearranged level, and the IC (IC2) reverses to output 0 and is inputted in pin 6, whereupon the microprocessor (153) memorizes mode 2, while pins 28 and 27 output 1 and 0 17 signals respectively, setting in operation the LED (D7) to indicate the state of operation.

On the other hand, while the motor is at rest, namely, when the oilpressing operation has not yet begun, the output at pin 15 rests at 0, and the diode (D20) of the preheating temperature raising circuit (161) turns on and the resistor (R3) of the temperature detecting circuit (151) and the resistor (R10) of the preheating temperature raising circuit (161) are connected in a series, whereupon the basic level voltage of the IC (IC2) is lowered. Until the temperature rises to lower the resistance of the thermistor (Thl), the reversion at the IC (IC2) does not occur; thus for the time of preheating the cylinder (117), the cylinder (117) is heated to a higher temperature than is required in the nomal oil-pressinoperations and this causes a result of lowering of the viscosity of the oil pressed in the beginning to some degree, thus preventing the motor (M) from being over burdened at the begining. But directly after the motor (M) is set in operation the diode (D20) is turned off (because pin 15 is shifted to 1) and the temperature of the cylinder (117) returns to the preset level and remains there while the oil-pressing operation continues.

Then a return to KA in A of Fig. 3 takes place and mode 2 is selected (mode 2 was memorized in 18 the preceeding process). In mode 2 (1) of Fig. 3), determining whether the input at pin 22 stands at 1 or not is first performed by the overcurrent detection circuit (157) to determine if any irregularity has eccured to cause a flowing of an overcurrent to the motor M; in the event of irregularities causing a flow of an overcurrent, with the input at pin 22 being 1, the LED (D9) is eluminated to indicate so; but, in case there is no irregularity, and the input at pin 22 is other than 1, then pin 15 outputs 1 to set the motor (M) in operation.

Then, after it is determined whether or not sesame has been fed to the inlet (121), the timer is set at zero. By the temperature detection circuit (151), it is determined whether or not the temperature of the pressing cylinder (117) has fallen lower than the appropriate level, and if it by any chance has, the heating circuit (152) is set in operation to raise the temperature and always maintains the temperature at the appropriate level. Should any irregularity occur such as an overcurrent flow into the motor (M), it is determined by monitoring the input at pin 22 connected to the output end of the overcurrent detection circuit (157), and the motor (M) stops outright. The LED (D9) is set to operate by indicating any possible occurrence of an irregularity. This process will continue in repetition until there is no sesame remaining in the 19 feeding inlet (121). When it is determined that there is no sesame remaining in the inlet (121), pin 5 outputs 1 through the feeding detecting circuit (150), which the microprocessor (153) instantly determines. The above process repeats itself for 20 seconds, [time necessary for the sesame in the pressing cylinder (117) to be completely strained. After the last sesame has passed through the feeder, and the last of the hulls are emptied into the receptacle container the time can, when needed, be either lengthened or reduced], and after the 20 seconds or the time needed has passed, the motor (M) stops, the LED (D8) is set in operation to indicate that the press is in the state of waiting while memorizing the required mode to prepare for the next pressing operation, or the power is manually switched off.

As has been described above, in the control device of the present invention, the proper temperature is maintained before and during the oilpressing operation, respectively, not only is the yield of oil high and its quality excellant but, the underheating and overheating at the time of preheating is prevented. Preventing damage of the motor from burning due either from the motor stopping or from the blocking of the feeding inlet.

Moreover, the present invention also has a power source voltage detection circuit, a trigger.

synchronizing circuit, and a tap-shifting circuit so that when both 10Ov and 220v currents are available it is instantly detected which is in use and if. necessary the tap is of itself shifted from 10Ov to 220v and vice' versa: to keep the power consumption for the heater almost the same in either case the heating circuit operates to allow the flow of the current only for one fifth of the whole section in the case of 22Ov [when 220v power is applied on a same load (resistance), the consumption of power will be the square of 2.2, that is 4.84, roughly five times that consumed at 11Ov); and by the synchronous signals from the synchronizing circuit the heating circuit is triggered at its zero- cross point, this triggering is quite accurate and easy, whereby power from both 10Ov and 220v can be used without fixing a separate device for the supply of power.

- In the present invention, because the oil- pressing cylinder is sufficiently preheated before the pressing begins there is no possibility of an overcurrent flow due to an overburden. To add to the safety the overcurrent detection circuit is included so that if a flow of an overcurrent occurs by any cause whatsoever, the power source of the motor will automatically be turnd off, thus preventing damage to the motor from burning or any other disorders of a similar nature.

21 state of operation is very easy'to operate the a malfunction the correct obtained. The t is capable of a certain extent before the pressing of oil begins) than the temperature that is required during the operation, thus allowing a smooth start for the motor and preventing any overburden to the motor at the begining of operation.

The control device of the present invention is constructed to function automatically by the pro-ram, sorted in the microprocessor. Only one switch is needed. Once power is switched on there is no need for any other switches to control the separate steps.

In the present invention it is also possible to undertake some changes or alterations although they do not deviate from the technical idea given below in the claims of the present invention.

Also, because the indicated at each step, it is press, and in the event of step for remedy can be instantly preheating temperature raising circul raising the temperature higher (to

Claims

A control device for an oil-pressing which comprises: a feeding detection means for detecting whether sesame or other seed to be pressed has or has not been fed into the oil press; a temperature detection means for detecting the temperature of an oil-pressing cylinder; a cylinder heating means for heating the oil-pressing cylinder; a power switching means for switching the power for a motor on or off; and a microprocessor connected to all said means: The microprocessor controls said cylinder heating means and said power switching means by treating the output of said feeding detection means and said temperature detection means.
2. The invention of Claim 1 wherein, said feeding detection means includes a LED (DII) and a resistor (R5) which are connected in serial, resistors (R6, R7, R8) and a photodiode (D12) which make a bridge circuit, and IC (IC1) connected between the microprocessor and the bridge circuit, where said photodiode (D12) and the LED (D11) is mounted on the feeding inlet (121); said temperature detection means includes a thermistor (Thl) mounted on a cylinder, and resist-ors (R1, R2, R3) which form a bridge curcuit with said thermistor (Thl) IC (IC2) connected between the microprocessor and the bridge circuit.
3. The invention of Claim 1 wherein, said control device for an oil press further includes a power voltage detection circuit (158) for detecting the voltage of power source, the trigger synchronizing circuit (159) for synchronizing and triggering said cylinder heating means at its zerocross point, and the tapshifting circuit (155) for executing the shift of the motor taps.
4. The invention of Claim 3 wherein, said power voltage detection circuit (158) includes resistros (Rll, R13) connected to one terminal (VA) of the direct voltage varing corresponding to variation of the power voltage, resistors (R12, R14) connected to one terminal (M) of constant direct voltage, and IC (IC3) connected between the microprocessor and the connected point of the resistors (Rll, R13) and resistor (R12, R14).
5. The invention of Claim 3 wherein said trigger synchronizing circuit (159) includes a transistor (Q2), a resistor (R21) and a capacitor (CO, where the base of the transistor (Q2) is connected to the power voltage through the resistor (R21) and the capacitor (CO, the collector and the emitter of the transistor (Q2) is connected to the microprocessor and the earth respectively.

- 24
6. The invention of Claim 3 wherein, said tap-shifting circuit (155) includes a transistor (Q3), relay (Ry) and a resistor (R22), where the collector of the transistor (Q3) is connected to one terminal (CC) of the relay (Ry), the base of the transistor (Q3) is connected to the microprocessor through the resistor (R12).

1
7. The invention of Claim 3 wherein the control device further includes an overcurrent detection circuit (157) for detecting the over current of the motor (M), and a preheating temperature raising circuit (161) for raising the temperature of the cylinder.

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