JP2751156B2 - Control device for electromagnetic vibrator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an electromagnetic vibrator such as an electromagnetic feeder, a parts feeder, and a vibrator provided with an exciting coil and a control circuit for supplying an intermittent current thereto. Things. [Prior Art] In general, an electromagnetic vibrator uses a combination mechanism of an electromagnet and a spring to intermittently supply an exciting current to an exciting coil intermittently to generate an intermittent magnetic attraction force and a spring restoring force. Vibration is obtained by the interaction. As described above, the means for periodically supplying a current to the excitation coil for the electromagnetic vibrator supplies a full-wave or half-wave rectified voltage of a commercial frequency to the excitation coil. At this time, the spring is used at the commercial frequency (at half-wave rectification) or twice the commercial frequency (at full-wave rectification).
In order to resonate, it is adjusted to resonate by changing the number of layers or changing the spring. This spring adjustment
Not only is it troublesome, but also requires considerable skill, but in order to omit this spring adjustment, a single-phase inverter circuit can be used as a variable frequency power supply, which can be replaced by frequency adjustment. The electromagnetic vibrator provided with the control means by this single-phase inverter is as shown in FIG. In FIG. 3, reference numeral 1 denotes a DC power supply, which is configured by rectifying a commercial power supply voltage and removing a ripple with a smoothing capacitor. 2 is the inverse transform circuit, the transistor 2T ₁ ~2T ₄ and four diodes 2D ₁ ~2D ₄ as four switching elements
Are configured with the connections shown. The DC power supply 1 is connected to the input side of the inverse conversion circuit 2, and the excitation coil 3 for the electromagnetic vibrator is connected to the output side. 4 is a base driving circuit transistor 2T ₁ ~2T ₄ in the inverse transform circuit 2. Applying the above configuration, each transistor 2T ₁ ~2T ₄ involves the operation of the base drive circuit 4, for example, an inverted transformation action based on the well-known PWM method, an AC voltage of desired frequency electromagnetic vibration machine excitation coil 3 I do. At this time, a current delayed by approximately 90 degrees with respect to the AC voltage is supplied to the exciting coil 3, and the direction of the current flowing into the exciting coil 3 changes according to the output frequency of the inverse conversion circuit 2. At this time, even if a current flows in either direction to the excitation coil 3, a magnetic attraction force can be obtained.
Interaction with the restoring force of the spring of the electromagnetic vibrator generates a vibration twice the output frequency of the inverse conversion circuit 2. [Problem to be Solved by the Invention] In the control circuit of the electromagnetic vibrator shown in FIG.
It requires four switching elements such as transistors as ordinary single-phase inverters, and requires a drive circuit for these switching elements and a power supply for the drive circuit. In particular, when PWM control is employed, the voltage level is not reduced and remains constant even when the polarity of the voltage is switched, so that the conduction switching of a pair of switching elements is performed to prevent an arm short circuit of each switching element. It is necessary to provide a sufficient dead time at the time, and control of the switching element tends to be complicated. [Means for Solving the Problems] According to the present invention, the exciting coil for the electromagnetic vibrator as a unique property of the electromagnetic vibrator is an almost pure inductive load, and the direction of the current flowing through the exciting coil is different from the operation. It was made with a focus on being unaffected. That is, the gist of the present invention is a control device that intermittently supplies an excitation current regulated in one direction to an excitation coil for an electromagnetic vibrator,
The objectives are as follows: (A) an excitation coil that performs an electromagnetic vibration action; (B) a current is supplied from each terminal of the excitation coil to a DC power supply via an independent switching element, and from the DC power supply to the excitation coil. Circuit means (C) two diodes connected in series with each of the switching elements and having opposite polarities to the DC power supply and forming a closed circuit with the DC power supply and the exciting coil ( D) A drive circuit for performing PWM control of each switching element so as to supply a current in a constant direction to the excitation coil at a constant cycle. This is achieved by an electromagnetic vibrator control device comprising: [Operation] Based on the control of two switching elements (transistors), an alternating voltage obtained by a PWM method is applied to the excitation coil for the electromagnetic vibrator, and a current in a constant direction is intermittently applied to the excitation coil. Thereby, a magnetic attraction force is intermittently applied, and an exciting force is obtained by interaction with the restoring force of the spring. [Example] Hereinafter, the example shown in Fig. 1 will be specifically described. In FIG. 1, reference numeral 11 denotes a DC power supply. Reference numeral 12 denotes an inverse conversion circuit, which includes transistors 12T ₁ and 12T ₂ and a diode 12
D ₁ and 12D ₂ are bridge-connected as shown, and the input side is connected to the DC power supply. Then, output points P ₁ and P ₂ of the inverse conversion circuit 12 are connected to respective input terminals of the excitation coil 13 for the electromagnetic vibrator. Reference numeral 14 denotes a base drive circuit of the transistors 12T ₁ and 12T ₂ , which is constituted by well-known circuit means including a triangular wave generator, a sine wave generator, a comparator, a polarity inversion circuit, and the like as components for performing PWM control. In the above configuration, the base drive circuit is
In the process of performing the PWM control on T ₁ and 12T ₂ , an output as shown in FIG. Generation of the output, at the output P _1, when transistor 12T ₁ is turned off the output zero potential (hereinafter, referred to as "L"), during the on the potential of the DC power supply 11 (hereinafter, referred to as "H") and It becomes possible, at the output end P _2, transistor 12
T ₂ off at the time of "H", on-time is achieved by a combination of that becomes "L". That is, the output terminal P ₁ is “H” and the output terminal P ₂
There "L" voltage of the positive direction is issued when the output terminal P ₁ is "L"
When the output P ₂ is "H" voltage in the negative direction is obtained. On the other hand, when the output terminals P ₁ and P ₂ are both “L” or “H”, the output is regulated to be 0. Such a transistor
Assuming that the output shown in the second graph (a) is given to the excitation coil 13 based on the PWM control of 12T ₁ and 2T ₂ , this effective sine wave is obtained as shown in the second graph (b). As a result, the current flowing into the exciting coil 13 is reduced to the output terminal P ₁
When the but "H" output P ₂ is "L" DC current 11 → transistor 12T ₁ → exciting coil 13 → transistor 12T ₂ → DC power source 11
Flows in the closed circuit, the output end P ₁ is "L", the exciting coil when the output terminal P ₂ is "H" becomes current decrease, the exciting coil 13 → diode 12D ₁ → DC power source 11 → diode 12D ₂ → excitation Coil 13
Flows into a closed circuit. Based on the above operation, a current is intermittently applied in one direction to the excitation coil 13 for the electromagnetic vibrator, and the interaction between the electromagnet and the restoring force of the spring provided in the electromagnetic vibrator is performed. Drive. [Effects] As described above, the control device for an electromagnetic vibrator according to the present invention skillfully utilizes the characteristics of the electromagnetic vibrator (operates with a very small energy supply sufficient to compensate for the damping due to the resonance of the spring). The gist of the present invention is to supply power to the exciting coil for the electromagnetic vibrator and supply a discontinuous current in only one direction. Accordingly, the number of switching elements is four compared to the conventional single-phase inverter circuit.
It is a conventional single-phase full-wave inverter circuit that halves the number from two to two. In PWM control, there is no need to consider providing an appropriate dead time to prevent arm short-circuiting, and the drive circuit for these switching elements is simplified. Practical that can be achieved. Furthermore, the effective current required to apply the same excitation force is compared with the case where the excitation coil for the electromagnetic vibrator is driven by a single-phase inverter circuit for full-wave rectification that changes the direction of the current flowing through the coil for the electromagnetic vibrator as before. Assuming that the maximum value of the current flowing through the switching element is 2Idc, in the conventional full-wave rectification type single-phase inverter circuit, On the other hand, in the control device according to the present invention, Becomes Therefore, the effective current required to apply the same exciting force to the electromagnetic vibrator is reduced to about 86%.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a graph for explaining the operation, and FIG. 3 is a conventional circuit diagram. 11 DC power supply 12 Inverting circuits 12T ₁ and 12T ₂ Transistors 12D ₁ and 12D ₂ Diode 13 Excitation coil for electromagnetic vibrator 14 Base drive circuit

Claims (1)

(57) [Claims] A control device for an electromagnetic vibrator having the following components (A to D): (A) an exciting coil that performs an electromagnetic vibration action; and (B) an excitation coil that performs an electromagnetic vibration action. Circuit means (C) connected to the DC power supply in a polarity in which a current is supplied from the DC power supply to the exciting coil. (C) The DC means connected in series to the switching elements and in the opposite polarity to the DC power supply. Two diodes (D) forming a closed circuit with a power supply and the excitation coil (D) A drive circuit for performing PWM control of each switching element so as to supply a current in a constant direction to the excitation coil at a constant cycle. .