JP2006230194A - Refrigeration system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protective device of an electric motor adapted to suppress, protect the temperature rise inside an electrical box in which a protection device intends to be arranged, as well as to quickly release abnormal rapidly increasing electric currents, at the occurrence of the lock phenomenon of an electric motor and a short-circuit fault between phases of motor windings, a ground fault due to continuity between a motor winding and a metallic housing of a compressor or any other abnormal situations. <P>SOLUTION: A protection device includes an overload relay, consisting of dissolved elements connected in series, temperature switches, a heater and a bimetal, and installed inside an electrical box, two connecting terminals consisting of an input terminal and an output terminal of the relay connected between AC power supply and an electric motor via a switch for an electromagnetic contactor, a center terminal connected to the input terminal of the electromagnetic contactor that opens and closes electric currents to the motor led out from the bimetal, and blocks overcurrents of the motor according to a signal from the center terminal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a motor protection device that controls energization of a motor used in a compressor or the like, and functions to detect and detect the occurrence of any abnormality in the motor to protect the motor.

  Today, compressors used in commercial refrigerators, showcases, etc. and refrigerant circuits including them are detected as soon as any abnormality occurs in the compressor or refrigerant circuit, and the power supply to the compressor is stopped. And a protective device for the compressor that reduces the current. For example, in Japanese Patent Application Laid-Open No. 7-201262, an overcurrent protection device that prevents a compressor motor from being burned due to an overcurrent caused by an overload state or a lock state of the compressor between an electric compressor and a power source. Are provided.

  On the other hand, as an overload relay when the protective device is made into parts, a plan view (a) and a front view (b) thereof are shown in FIG. 4, and an electric circuit diagram thereof is shown in FIG. The overload relay 1 is a cylindrical body having an internal cavity, and includes an accommodating portion 2 that accommodates the heater 11 and the bimetal 12 therein, and an ear portion 3 provided on one end side of the accommodating portion 2.

  The overload relay 1 is used by connecting a part of the overload relay 1 to a socket member having a female fixed terminal (not shown). Two male-type relays for connection to a power source and an electric motor when connected to the socket portion are used. It has connection terminals 5 and 6 and a male center terminal 7 connected to some part. In the figure, “A” indicates connection to the electric motor side, and “B” represents a connection destination indication indicating connection to the power source side. That is, it is clearly shown that the connection terminal 5 corresponds to A and the connection terminal 6 corresponds to B.

The bimetal 12 includes a first connection terminal 12A connected to the connection terminal 5 for connection to a power source (not shown), a second connection terminal 12B connected to the heater 11, and a third connection terminal 12C connected to the center terminal 7. And the first connection terminal when heated by the heater 11 whose calorific value changes in proportion to the current and becomes higher than its operating temperature (open temperature corresponding to the open current) by the bimetal contact piece. 12A and the second connection terminal 12B are opened to stop energization of the motor, while when the temperature drops below the return temperature, both terminals 12A and 12B are closed and energization to the motor side is resumed. is there.
JP-A-7-201262

The overcurrent protection device disclosed in Japanese Patent Application Laid-Open No. 7-201262 obtains the original characteristics of a bimetal piece when the life of the bimetal piece has been reached due to repeated forward and reverse operations. In order not to satisfy the overcurrent protection function, another bimetal piece with an operating temperature higher than that of this bimetal piece is used to take measures against this life while improving safety. It is.

  The heat generation amount of each bimetal piece changes according to the energization current. Specifically, the heating temperature of the bimetal contact piece reaches the operating temperature of each bimetal piece by being heated by the heat of the heater which increases the heat generation amount when the energization current increases. In this case, the respective contacts are opened so as to cut off the power supply to the compressor (particularly the electric motor).

  However, the bimetal contact piece is closely related to the following four elements: the ambient temperature in which it is placed, the current flowing through the heater, the temperature of the heated contact piece, and the duration of a state. The operation is controlled, and it is generally not possible to define the operation start temperature and the return temperature only by the temperature of the contact piece. As described above, there is a fear that an accurate temperature cannot be detected only by the overcurrent protection device, and an actual protection circuit has been provided with a temperature sensor and a temperature switch that opens and closes a contact by temperature detection. In addition, the bimetal that uses the temperature change due to heating by the current-responsive heater has a time lag including the above-mentioned duration until its operation, and due to the time lag on the characteristics of this bimetal, not only the motor but also other electric parts However, there is a case where an adverse effect due to an abnormal overcurrent (that is, an abnormal current) that increases instantaneously occurs, and a fuse is separately provided to protect other electrical components. In addition, the temperature switch and the fuse are configured separately from the overcurrent protection device (bimetal with a heater). This is obvious from the overload relay as an electrical component in FIGS. 4 and 5 because it is not particularly described in the circuit configuration in FIG.

  Accordingly, it is necessary to connect the overcurrent protection device, the temperature switch, and the fuse, and to secure a space for arranging the three components, which increases the number of components and complicates the installation work. Moreover, by arranging the temperature switch in the electrical box, the temperature rise in the space (in the electrical box) where these electrical components are placed can be suppressed, but since there is no fuse, the rotor of the motor stops (especially Even when the motor lock phenomenon) or during its operation, it increases rapidly when an abnormal situation such as a short circuit failure between the phases of the motor windings or a ground fault due to conduction between the motor windings and the metal casing of the compressor occurs. The current could not be detected quickly, and this abnormal current could not be interrupted.

  Therefore, in the present invention, in addition to suppressing / preventing temperature rise in an electrical box provided with a protective device for protecting an electric motor used for a compressor or the like, a motor winding is generated when an electric motor lock phenomenon occurs or during other abnormalities. As a result of deterioration and burnout, a rapidly increasing current (ie, abnormal current) can be detected and released quickly due to a ground fault current or a short-circuit current generated between the motor and the power supply or its operating circuit. An object of the present invention is to provide a motor protection device that protects a compressor from damage.

  In order to solve the above-mentioned problems, an invention according to claim 1 is an overload relay comprising an element, a temperature switch, a heater, and a bimetal, which are connected in series inside a cylindrical resin container and are fused by an abnormal current. In the above, the relay is derived from the inside of the resin container to the outside, and is connected between the AC power source and the electric motor via an open / close switch, two connection terminals serving as an input terminal and an output terminal of the relay, A center terminal led from the bimetal to the outside of the resin container and connected to a detection signal line for controlling opening and closing of the open / close switch at a substantially center of the resin container, the element, the temperature switch, and the heater And the bimetal is connected in series between the input terminal and the output terminal in that order, and the operating temperature of the bimetal is higher than the operating temperature of the temperature switch. Is set low, it is to prevent overcurrent of the motor based on the detection signal from the center pin.

  The invention according to claim 2 is an overload relay that is connected in series inside a cylindrical resin container and that is fused by an abnormal current, a temperature switch, a heater, and a bimetal, wherein the relay includes the resin Two connection terminals serving as an input terminal and an output terminal of the relay connected to an AC power source and an electric motor, which are led out from the inside of the container and connected via an open / close switch, and substantially at the center of the resin container A center terminal connected to a detection signal line that is led out from the bimetal to the outside of the resin container and controls the opening and closing of the opening and closing switch, and the element, the temperature switch, the heater, and the bimetal are the input A series connection between the terminal and the output terminal, the fusing current of the element is set to a value larger than the breaking current of the bimetal, the center Wherein the blocking overcurrent of the motor based on the detection signal from the child.

  According to a third aspect of the present invention, there is provided an overload relay connected in series inside a cylindrical resin container, the element being fused by an abnormal current, a temperature switch, a heater, and a bimetal, wherein the relay is the resin container Two connection terminals that are an input terminal and an output terminal of the relay connected to an AC power source and an electric motor through an open / close switch and led from the inside to the outside, and from the bimetal at substantially the center of the resin container A center terminal led to the outside of the resin container and connected to a detection signal line for controlling the opening and closing of the opening and closing switch, the element, the temperature switch, the heater, and the bimetal are the input terminal and The output terminals are connected in series in that order, and the operating temperature of the bimetal is set lower than the operating temperature of the temperature switch. Flow is set to a value greater than the cut-off current of the bimetal, characterized in that it prevents the overcurrent of the motor based on the detection signal from the center pin.

  According to a fourth aspect of the present invention, in the motor protection device according to the first to third aspects, the fusing time of the element is set to 1 second or less.

  According to the motor protection device of the first aspect of the present invention, in the overload relay composed of an element that is blown by an abnormal current, a temperature switch, a heater, and a bimetal, the relay includes two connection terminals that serve as an input terminal and an output terminal. A center terminal, and the element, the temperature switch, the heater, and the bimetal are connected in series between the input terminal and the output terminal in that order, and the operation temperature of the bimetal is controlled by the operation of the temperature switch. By setting the temperature lower than the temperature, the relay is not particularly required to be attached to the surface of the compressor, and can be attached to a place where temperature management is necessary, such as an electrical box or an outdoor unit of an air conditioner. In addition, the temperature switch can detect the temperature rise of other protection devices and electrical components in the electrical box and can operate quickly.

  According to the motor protection device of the second aspect of the present invention, in the overload relay comprising an element that melts by an abnormal current, a temperature switch, a heater, and a bimetal, the relay includes two connection terminals that serve as an input terminal and an output terminal. A center terminal, and the element, the temperature switch, the heater, and the bimetal are connected in series between the input terminal and the output terminal in that order, and the blowing current of the element is changed to the cutoff current of the bimetal. By setting the value to a larger value, prior to driving the bimetal, when the rotor of the motor is stopped by the element or during its operation, a short circuit failure between the phases of the motor winding or the metal casing of the motor winding and the compressor When an abnormal situation such as a ground fault due to continuity with the body occurs, a rapidly increasing current is quickly detected and the power to the motor is cut off. It will be able to, the abnormal current can be quickly detected and canceled, it is possible to extend the lifetime of the said bimetal.

  According to the invention according to claim 3, in the overload relay composed of an element that melts by an abnormal current, a temperature switch, a heater, and a bimetal, the relay includes two connection terminals that serve as an input terminal and an output terminal, and a center terminal. The element, the temperature switch, the heater, and the bimetal are connected in series between the input terminal and the output terminal in that order, and the operating temperature of the bimetal is set lower than the operating temperature of the temperature switch. In addition, by setting the fusing current of the element to a value larger than the breaking current of the bimetal, the relay can be used as a temperature detection and overcurrent detection component, and the life of the bimetal can be extended. Can be planned.

  According to a fourth aspect of the present invention, in the motor protection device according to any one of the first to third aspects, by setting the fusing time of the element to 1 second or less, a short circuit fault or a ground fault in the motor winding It is possible to quickly detect and cancel a current that rapidly increases in the event of an abnormal situation.

  EXAMPLES Next, although an Example demonstrates this invention in more detail, this invention is not limited by these.

  Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is an electric circuit diagram of a three-phase AC power source (not shown) and a power supply unit (that is, a motor control device) connected to the three-phase motor using two motor protection devices according to the present invention. The figure which consists of a top view (a) and a front view (b) of the overload relay which made the protection device of the motor into a part, FIG. 3 is an electric circuit diagram of the electrical components arranged inside the overload relay of FIG. . In addition, the same code | symbol is used about the same structure as the past.

  In FIG. 1, the motor control device includes a terminal plate 21 connected to a three-phase AC power source (not shown), a three-phase motor 22 for the compressor, and three-phase terminals R, S, T of these terminal plates 21 and three-phase. An electromagnetic contactor 23 serving as an opening / closing switch is connected between the three-phase terminals r, s, t of the electric motor 22. Further, an overload relay 1b is connected between one terminal R of the terminal plate 21 and the open / close terminal of the electromagnetic contactor 23 so that the connection terminal 6 is connected to R and the connection terminal 5 is connected to the electromagnetic contactor 23, respectively. The overload relay 1a is connected between one terminal T of the plate 21 and the open / close terminal of the electromagnetic contactor 23 so that the connection terminal 6 is connected to R and the connection terminal 5 is connected to the electromagnetic contactor 23, respectively.

  The center terminal 7 of the overload relay 1a is connected to the input terminal 23a of the electromagnetic contactor 23 through the connection line 8a, and is connected to the terminal Z of the terminal plate 21 through the electromagnetic coil 23c and the connection terminal 23b. In addition, this overload relay 1a shall be arrange | positioned in the electrical equipment box which is not shown in figure.

  Due to the connection circuit of this overload relay 1a, the magnetic contactor 23 is normally energized when the bimetal contact piece of the overload relay 1a is closed, that is, when no abnormal current flows in the T phase. When the bimetal contact of the overload relay 1a is opened due to an abnormal current, the abnormal signal from the center terminal 7 is received, the energization to the input terminal 23a is cut off, the electromagnetic coil 23C is de-energized, and the electromagnetic contactor 23 drive contact pieces 23d are opened. For this reason, when detecting an abnormal current, the electromagnetic contactor 23 cuts off the power supply to the three-phase motor 22 and operates to protect the three-phase motor 22.

  The center terminal 7 of the overload relay 1b is connected to a terminal plate 21 via a connection line 8b via a temperature switch 24, a reverse phase prevention relay 25, and a high / low pressure switch 26 which are attached to a metal casing of a compressor (not shown). The terminal Z and the connection terminal 23b of the electromagnetic contactor 23 are connected to the center terminal 7 of the overload relay 1a through the electromagnetic coil 23c and the input terminal 23b.

The connection circuit of the overload relay 1b closes the bimetal contact piece of the overload relay 1b, that is, when no abnormal current flows in the R phase, and the temperature switch 24 closes, When the phase prevention relay 25 and the high / low pressure switch 26 are operating normally, the magnetic contactor 23 is normally energized, and the bimetal contact of the overload relay 1b is opened due to an abnormal current. Alternatively, when the temperature switch 24 detects an abnormally high temperature of the compressor and opens, or when the anti-phase relay 25 or the high / low pressure switch 26 is activated, the center terminal 7 or the temperature switch 24, Alternatively, in response to an abnormal signal from the reverse phase prevention relay 25 or the high / low pressure switch 26, the connection terminal 23b is de-energized and the electromagnetic coil 23C is de-energized. Will drive the contact piece 23d of the electromagnetic contactor 23 is opened. For this reason, when an abnormal current is detected, when an abnormally high temperature of the compressor is detected, or when a reverse phase is generated or when an abnormal pressure is generated, energization of the three-phase motor 22 is interrupted by the electromagnetic contactor 23, and the three-phase motor 22 is cut off. Works to protect.

  2 is greatly different from the conventional example of FIG. 4 in that the orientation of the connection terminal 6 and the terminal terminal 7 is not parallel to the connection terminal 5 but at an angle of approximately 90 °. The circuit configuration in FIG. This difference in circuit configuration will be described with reference to FIG. 2 is a connection line as a signal transmission signal line connected to the center terminal 7 and corresponds to 8a and 8b in FIG.

  In this overload relay 1, by arranging the connection terminals 5 and 6 in an orthogonal relationship, the degree of freedom with respect to determining the orientation of the center terminal 7 is increased as compared with the prior art. However, since the number of circuit elements arranged in the storage unit 2 is increased, the degree of freedom is not substantially different from the conventional one.

  In FIG. 3, on the connection terminal 6 side of the heater 11, a temperature switch 13 that opens a contact when the temperature of the detection target located in the vicinity of the ear 3 in the storage unit 2 becomes abnormally high, and an excessive current A fuse 14 that is blown at the time of detection is connected in that order.

  The bimetal contact piece in the bimetal 12 has four ambient temperature in the space where the overload relay 1 is arranged, the current flowing through the heater 11, the temperature of the heated contact piece, and the duration of a certain state. The elements are closely related and the operation is controlled, and the operation start temperature and the return temperature cannot be defined only by the temperature of the bimetal contact. On the other hand, the duration of the contact opening temperature of the temperature switch 13 is set to be shorter than the duration of the bimetal piece, and the operating current of the bimetal piece is based on the fusing current of the fuse 14 (for example, about several hundred A). The duration of the fuse 14 is, of course, much shorter (for example, set to 1 second or less).

  In particular, if the operating temperature of the bimetal contact piece of the overload relay 1b arranged in the R phase is set lower than the operating temperature of the temperature switch 24 attached to the metal casing of the compressor, the overload relay 1b is not particularly required to be provided on the surface of the compressor, and can be attached to a part requiring temperature management, such as in an electrical box or an outdoor unit of an air conditioner.

  According to the above configuration, since the overload relay 1a is provided in the electrical box, wiring processing in the electrical box in which the electrical component, for example, the electromagnetic contactor 23 is provided can be easily performed, while the center terminal 7 of the relay 1a can be used. This detection signal can be used as an input signal to the electromagnetic contactor 23 and other control means, so that the overload relay 1a can be used as a temperature and overcurrent detection component. Further, the temperature switch 13 in the overload relay 1a can detect a temperature rise of a protection device such as an overload relay in the electrical box or an electrical component, and can quickly cancel the temperature rise. And versatility improved.

  In particular, by disposing the overload relay 1a in the vicinity of the magnetic contactor in the electrical box, the overload relay 1a itself can be used as a temperature detection and overcurrent detection component, and the energization to the motor 22 is controlled. The temperature increase of the magnetic contactor 23 was detected and the current supply was quickly controlled to suppress the temperature increase.

  Also, a fuse 14 is provided on the input side of the overload relay 1 as an element that is blown by an overcurrent, and the blowing current in the fuse is set to a value (for example, several hundred A) larger than the open (cutoff) current of the bimetal 12. At the same time, by shortening the fusing time (for example, set to 1 second or less), the fuse 14 stops the rotor of the electric motor 22 before the bimetal 12 is driven (contact opening) (particularly, a motor lock phenomenon occurs). Current) that suddenly increases during operation (ie, abnormal current) when an abnormal situation such as a short-circuit fault between the phases of the motor windings or a ground fault due to conduction between the motor windings and the compressor metal housing occurs. Can be detected quickly, and the power supply to the motor 22 can be cut off, so that an abnormal current can be detected and canceled quickly. The life as the tall 12 can be extended.

  If the fuse 14 is positioned closer to the electric motor 22 than the bimetal 12, even if an abnormal current is detected by the fuse 14 and energization of the drive contact piece 23 d of the electromagnetic contactor 23 is prevented, the bimetal 12 Since the energization to the electromagnetic coil 23c of the electromagnetic contactor 23 is continued through the center terminal 7, the driving contact piece 23d cannot be forcibly opened, and the operation of the overcurrent preventing fuse 14 is activated. It becomes impossible to stop the energization to the electric motor 22 only with this.

  For this reason, in this embodiment, the fuse 14, the temperature switch 13, the heater 11, and the bimetal 12 are connected in series in that order between the input terminal 6 and the output terminal 5 of the overload relay 1 due to abnormal current. This solves this problem. In addition, when an abnormal current is detected by the fuse (melting element) 14, an abnormal temperature rise of the electrical box is detected by the temperature switch 13, and an overcurrent is separately detected by the bimetal 12, and any of these abnormalities is detected at the same time The overload relay 1 (specifically, the electromagnetic contactor 23) can forcibly block the drive current to the motor 22, and the operation of the motor as a protection device can be made more reliable.

It is an electric circuit diagram in the control apparatus of the electric motor which uses two protection devices of the electric motor concerning the present invention. It is the top view (a) and front view (b) of the overload relay which made the protection device of this invention a component. It is an electric circuit diagram of the overload relay of the present invention. It is the top view (a) and front view (b) of the conventional overload relay which made the protective device a component. It is an electric circuit diagram of the conventional overload relay.

Explanation of symbols

1, 1a, 1b Overload relay 2 Storage part 5 Connection terminal (motor side)
6 Connection terminal (power supply side)
7 Center terminals 8, 8a, 8b Connection line (abnormal signal line)
DESCRIPTION OF SYMBOLS 11 Heater 12 Bimetal 13 Temperature switch 14 Fuse 22 Three-phase motor 23 Electromagnetic contactor

Claims (4)

In an overload relay consisting of elements, temperature switches, heaters, bimetals, which are connected in series inside a cylindrical resin container and melted by an abnormal current,
The relay is derived from the inside of the resin container to the outside, two connection terminals serving as an input terminal and an output terminal of the relay connected between an AC power source and an electric motor via an open / close switch,
A center terminal connected to a detection signal line that is led out from the bimetal to the outside of the resin container at approximately the center of the resin container and controls the opening and closing of the open / close switch;
The element, the temperature switch, the heater, and the bimetal are connected in series between the input terminal and the output terminal in that order.
The operating temperature of the bimetal is set lower than the operating temperature of the temperature switch,
An electric motor protection device that prevents overcurrent of the electric motor based on a detection signal from the center terminal. In an overload relay consisting of elements, temperature switches, heaters, bimetals, which are connected in series inside a cylindrical resin container and melted by an abnormal current,
The relay is derived from the inside of the resin container to the outside, two connection terminals serving as an input terminal and an output terminal of the relay connected between an AC power source and an electric motor via an open / close switch,
A center terminal connected to a detection signal line that is led out from the bimetal to the outside of the resin container at approximately the center of the resin container and controls the opening and closing of the open / close switch;
The element, the temperature switch, the heater, and the bimetal are connected in series between the input terminal and the output terminal in that order.
The fusing current of the element is set to a value larger than the breaking current of the bimetal,
An electric motor protection device that prevents overcurrent of the electric motor based on a detection signal from the center terminal. In an overload relay consisting of elements, temperature switches, heaters, bimetals, which are connected in series inside a cylindrical resin container and melted by an abnormal current,
The relay is derived from the inside of the resin container to the outside, two connection terminals serving as an input terminal and an output terminal of the relay connected between an AC power source and an electric motor via an open / close switch,
A center terminal connected to a detection signal line that is led out from the bimetal to the outside of the resin container at approximately the center of the resin container and controls the opening and closing of the open / close switch;
The element, the temperature switch, the heater, and the bimetal are connected in series between the input terminal and the output terminal in that order.
The operating temperature of the bimetal is set lower than the operating temperature of the temperature switch,
The fusing current of the element is set to a value larger than the breaking current of the bimetal,
An electric motor protection device that prevents overcurrent of the electric motor based on a detection signal from the center terminal. 4. The protection device for an electric motor according to claim 1, wherein a fusing time of the element is set to 1 second or less.