JPH0515178A - Relay for starting motor - Google Patents

Abstract

PURPOSE: To provide a motor starter relay, which by using a resistance element having a positive resistance temperature coefficient, enables suppression of power consumption in resistance element during the rotation of a motor to a very low level and to rapidly cool a resistance element, in order to reset the relay quickly in preparation for the restart of the motor after the interruption of its rotation. CONSTITUTION: This relay consists of a resistor 2 made of a material which has a positive resistance temperature coefficient and whose resistance increases sharply when heated to a selected temperature level or higher, a pair of contact devices 4, 5, 6, 7 of a resilient, conductive metal which electrically contacts respectively both surfaces at opposing sides of the resistor 2 for connecting it to the start windings of a motor in series, and a container 1, made of a heat-insulating material, storing the resistor and contact devices. Furthermore, a pair of contact devices are arranged between each surface of the container 1 and the resistor 2, the majority part of the surface of which is held apart from the container.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-phase motor starting relay, and more particularly to a single-phase asynchronous motor starting relay used in a compressor of an electric refrigerator using an improved thermal relay. More specifically, the present invention uses a solid-state thermal relay that uses a wafer of material with a positive temperature coefficient (PTC) of electrical resistance. As the PTC material, a material of a kind well known to those skilled in this field is used.

[0002]

2. Description of the Related Art Conventionally, for starting a motor, a resistance element having a positive temperature coefficient of resistance is connected in series to the starting winding of a compressor motor of a refrigerator, etc. I'm trying to let the current flow. Thereafter, this resistance element is self-heated by the motor current, and is kept in a high resistance state while the motor is rotating. That is, the current flowing through the starting winding after the completion of the starting operation is made extremely small. Further, when the rotation of the motor is stopped by the function of the motor protection device or the like, the temperature of the resistance element is lowered to prepare for the next motor start. In the conventional configuration as described above, power is consumed by the resistance element even during normal rotation of the motor, which affects the operation efficiency of the motor at least to some extent. Further, when the resistance element is not sufficiently cooled, even if the motor is restarted, normal restart may not be performed depending on the state of the resistance element. Therefore, to reduce the power consumption of the resistance element to a very low level, and at the same time, if the motor is to be restarted immediately after it has been stopped, a resistor that cools rapidly after the motor is stopped so that the motor can be restarted immediately. It is desirable to use.

[0003]

SUMMARY OF THE INVENTION The present invention uses a resistance element having a positive temperature coefficient of resistance to suppress power consumption loss in the resistance element during motor rotation to a very low level, and to provide a motor after interruption of motor rotation. It is an object of the present invention to provide a motor starting relay in which the resistance element can be rapidly cooled in order to quickly reset the relay in preparation for restarting.

[0004]

A starting relay has a positive temperature coefficient of resistance and a resistor made of a material whose resistivity increases sharply when heated above a certain selected temperature level; A pair of resilient conductive metal contact devices for making electrical contact with opposite sides of the resistor to connect the resistor in series with the motor starting winding, and these resistors made of thermally insulating material. A pair of contacting devices arranged between the container and each side of the resistor, the majority of the surface of the resistor being held away from the container and contacting device. Has at least some conductive metal portion of a relatively high thermal resistance material, and
The container is small and spherical to substantially enclose the resistor and an essential part of the contactor in order to limit the thermal mass of the starting relay and the surface area to volume ratio of the container in order to cooperate with the heat transfer properties of the contactor. And it is firmly surrounded.

[0005]

The resistor is connected in series between the starting winding of the motor and the power source through the pair of contact devices. At the time of starting, the resistor has a low resistivity, so that a sufficient starting current flows to start the motor. However, when the start is completed, the self-heating of the resistor causes the resistivity to rapidly increase, so that no current flows in the start winding, and the motor continues to rotate due to the current flowing in the main winding. Both sides of the resistor are held away from the container by a pair of contact devices to prevent direct heat transfer from the resistor to the container, and the contact device is separated from the resistor by its relatively high thermal resistance conductive metal part. It also prevents heat transfer to the container via the contact device.
Also, the small, spherical container surrounding the resistor and contact device limits its surface area to volume ratio.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

First, referring to FIG. 1, a starting relay 50 according to the present invention using a thermal relay has a case (container) 1 made of an electrically and thermally insulating material. Materials having a positive temperature coefficient (PTC) as would be familiar to those skilled in the art (eg Danfoss A / S US Pat. Nos. 3,750,082 and 3,842). , 188) as a resistor. This PTC wafer 2 is adapted to be connected in series with the motor starting winding (Fig. 10a-
c) When starting the motor, the starting winding is excited through the wafer 2 and becomes de-energized when the starting of the motor is completed. At the start of starting the motor, the wafer 2 is relatively cold and has a low electric resistance, and a large current is supplied to start the motor. Due to this large current, the wafer 2 immediately begins to self-heat and the resistance gradually increases, which also reduces the current in the starting winding. This continues until the heat generated by the reduced current flowing through the wafer 2 equilibrates with the heat dissipated in the wafer 2. In the balanced state, the starting winding current is so small that the starting winding is substantially de-excited, but the wafer 2 is maintained at its balanced temperature. It is desirable that the size of the wafer 2 is smaller within a range in which the required function of the starting winding can be sufficiently realized. As a PTC material, conventionally used barium titanate ceramic by doping is used, and its Curie point temperature is 130 ° C. The standard wafer 2 has a diameter of 1.75 cm, and its weight is about 5 g for 220V motor and about 3 g for 120V motor starting.

The position of the wafer 2 is determined by a rib 3 on the inner surface of the case 1 and two leaf springs 4, 5 fixed to the electrical connecting devices 6, 7. The connecting devices 6 and 7 and the leaf springs 4 and 5 constitute a pair of contact devices. The connection devices 6 and 7 will be described in detail below. The leaf springs 4 and 5 have fins (or arms) 4a and 4b and 5a and 5b, respectively, which come into contact with the metal surfaces 8 and 9 attached to both surfaces of the wafer 2 by a conventional method. There is.

The electrical connection devices 6, 7 have "quick-connect" type terminals 10, 10 ', 11, 11' on the top and elastic "plug-on" on the bottom. -On) "connector 12,
13 is attached. "Plug on" connector 12,
13 is adapted to fit automatically when plugged into a pin 51.1 on an airtight connector (fuseite) or a suitable terminal board, indicated by reference numeral 51, on a refrigerator compressor. . The reason for using such an airtight connector 51 is that the refrigerator compressor motor is
It is conventionally housed in a hermetically sealed case, which requires an airtight connector 51 for connection with external wiring. The airtight connector 51 (generally called a fuseite connector) is
It has glass-sealed drawer pins, which are connected to the motor windings and from the motor case to each other,
It is also sealed to the case, electrically insulated, and protrudes from the case of the motor. The "plug-on" connectors 12, 13 are adapted to automatically adjust and fit over these hermetic connector pins. An airtight connector 51 for such a withdrawal pin is shown in FIGS.
c, the pin is designated by reference numeral 51.1 and in Figures 10a-c the black dots correspond to this. Further, the electrical connecting devices 6 and 7 are held at appropriate positions by projecting portions (or ribs) 14, 15 and 16, 17 formed inside the case 1. Outside the case 1, holes 18 and 1
9 is adapted to fit the pawl (or tongue) made on the lid of the device. The claw is not shown in FIG.

FIG. 2 is a sectional view of FIG. 1 taken along the line 2-2, showing the case 20 with the lid 20 fitted therein. The portion not shown clearly of the lid 20 is the broken line 21.
Outline. In other words, the curved portion 20a is connected to the wavy flat portion 20b, which is convenient for inserting the device of the present invention into the pin 51. 1 of the airtight connector 51 or other electrical connection device.

FIG. 3 is a sectional view taken along the line 3-3 in FIG. 1, showing the apparatus of FIG. 1 as an airtight connector (fuseite) 5.
1 (or other connection device) is shown in a separated state. In this figure, a lid 20 is fitted to the case 1, and pawls (or tongues) 22 and 23 for snapping the lid 20 are engaged with the holes 18 and 19, respectively. Terminal 1
0 and 11 are connected to the pin cable 56. The other elements have already been described and will not be repeated here.

FIG. 4 shows a top view of the lid partially shown in FIGS. 2 and 3. As shown in the figure, the rectangular flange element 24 has connection terminals 10, 1
Holes 25, 26, 27, 28 for passing 0 ', 11, 11'
And the holes 18 and 19 of the case 1 are fitted with claws (or tongues) 22 and 23 to be fitted therein. Further, in FIG. 4, a curved surface portion 20a and a wavy portion 20b are also shown. FIG. 5 shows FIG.
5 is a cross-sectional view taken along line 5-5 of FIG.

6 and 7 are respectively FIGS. 2 and 3.
Fig. 7 is a view of the lid partially shown in Fig.
It is a sectional view when it cuts by a line of. Shown in these figures are ribs 3.1, 3.2 on the inside of the lid 20, which define the position of the wafer 2 indicated by the dashed line 2a in FIG. These ribs surround the wafer 2. However, after the temperature of the wafer 2 reaches the temperature during the rotation of the motor, the heat conduction from the wafer 2 to the case 1 is minimized, that is, the wafer. The power loss of 2 is minimized. If the shape of the case 1 and the lid 20 is viewed as the whole relay, as shown in the figure, it has a roughly spherical outer shape, and the structure of the thermal relay is such that the surface area to volume ratio is minimized. The power loss after the temperature reaches the temperature during motor rotation is further reduced.

FIG. 8 shows the details of the electrical connection device 6 or 7 of the starting relay according to the present invention. The connection device 7 will be described. On its body 29, "quick connect" type terminals 11 and 11 'are formed, and a "plug-on" type socket 13 is welded to the body 29. Socket 13 is pin 5 on airtight connector 51
It is designed to be connected to 1.1. A thin spring 5 holding the wafer 2 and being in contact with the wafer 2 is fixed to the central portion of the main body 29, as described above with reference to FIGS. Spot welding is preferable as the fixing method to the main body.

FIGS. 9a and 9b are views showing details of the spring 5 for holding the wafer 2 of the starting relay (thermal relay) according to the present invention and contacting it.

The body 30 of the spring 5 has a suitable conductivity,
And it is made of a metallic material such as stainless steel, which has a relatively high thermal resistance, and its central portion 31 is
The starting relay is fixed (preferably by spot welding) to the main body 29 of the electrical connecting device 7. Also, the spring body 30 has two fins.
32, 33 and their narrowing ends 34,
35 is folded back. A layer 36 of highly conductive material (such as silver) is applied to each of these ends to ensure good electrical contact with the metal surface 8 or 9 of the wafer. Silver coating is "top-lay", "plating", "tape welding"
And the like. The springs 4 and 5 are made of a high heat resistance material to have a relatively small cross-sectional area, and the heat conducting portion between the springs 4 and 5 is made small so that the heat conduction from the wafer 2 to the case 1 is reduced. This is to reduce the power loss after the temperature of the relay reaches the temperature when the motor is rotating. That is, these springs serve as a thermal barrier between the wafer 2 and the thermal relay container 1. In order to effectively prevent the heat loss of the wafer 2, it is desirable that the thermal resistance R _T (second · ° C./calorie) of the springs 4 and 5 is about 1000 or more.

Further, from a mechanical point of view, the fins 32, 3 are
The fins 3 are provided with fin reinforcing ribs 37 and 38 so that the fins 32 and 33 are pressed against the wafer 2 with an appropriate pressure. Further, although not shown, it is conceivable to provide grooves in the fins 32 and 33 to suppress heat conduction through the springs 4 and 5. As a place to provide a groove,
The rib 37 at the center of the fin or the rib 38 can be considered. Although the spring 30 having the structure described above is one practical example, a coil spring can be used in the starting relay 50 of the present invention.

In the preferred embodiment of the present invention, the wafer 2 is chosen to be small in size, and as described above, the outer shape of the container of the thermal relay is approximately spherical and the spring 4 is used.
Since 5 and 5 also have large thermal resistance as described above, the loss from this thermal relay at the temperature when the motor is rotating is
When used for a 120V or 220V motor, the value is as small as about 2.0 W or less even if the motor is cooled for about 200 seconds or less in preparation for restarting after stopping the motor. In other words, in order to reduce the power loss in the thermal relay as much as possible, in the high resistance state the wafer 2
Even if the heat dissipation rate is suppressed so that the level of current flowing through it becomes low, this thermal relay has a structure with a small heat capacity as described above, so it will cool down within a relatively short time after the motor is stopped. You can return to the original state.

In addition, the wafer 2 and the springs 4 and 5
The spring structure and the coefficient K = stress / strain should be chosen such that the mechanical resonance frequency of the system is at a suitable frequency far away from the excitation frequency normally encountered. The excitation frequency is 50Hz to 60H in the case of a refrigerator motor compressor.
Those generated by the power source of z can be considered. Therefore, it is desirable that the resonance frequency of the spring-wafer system be 300 Hz or higher.

The "quick connect" terminals, two on each side of the wafer 2, enable the respective uses as shown in FIGS. 10a, 10b, 10c.

FIG. 10a shows start-up using only wafer 2, FIG. 10b shows start-up using wafer 2 and parallel capacitor 55, and FIG. 10c shows start-up using wafer 2 and series capacitor 55, respectively. In such a configuration, the wafer 2 initially supplies a large current to the starting winding for starting the motor, but when the self-heating period elapses, the temperature rises and the resistance increases. De-energize. Those skilled in the art are familiar with these circuit configurations and will not be described in detail here.

In the case of the circuit configuration of FIGS. 10a and 10b,
Connect the thermal relay to the airtight connector as shown in Figs. 1 and 2, that is, connect the thermal relay to the airtight connector 2
It is plugged into two pins and electrically connected.

On the other hand, when a series capacitor is used as in FIG. 10c, one pin of the hermetic connector is electrically connected to the thermal relay, but the other pin is not electrically connected but physically assisted. Connect the components to support the thermal relay.

FIGS. 11a-c show three examples according to the invention in which the circuit of FIG. 10c secures the thermal relay 50 to a three-pole airtight connector 51 on the motor.

In FIG. 11 a, one of the “plug-on” connectors 12, 13 and the auxiliary bracket 53 are used to secure the thermal relay 50 to the hermetic connector 51. FIG. 11B is an example in which the support portion 54 is directly formed on the case of the thermal relay 50. FIG. 11c is a modification of FIG. 11b with the support portion 54 in a different position than FIG. 11b.

FIG. 12 exemplifies an assembly line having a circular configuration for manufacturing the thermal relay used in the present invention. In the method according to the present invention described below,
There is a combination of "on-line" parts assembly and "turntable" parts assembly, and there is a synchronization between them. Each process of these lines will be described below.

First, the strip type connecting devices 6 and 7 are assembled into two assembly lines A, B and A '.
Put it in B '. At A and A ', the connectors 12 and 13 are supplied, and these are positioned and welded on the connecting devices 6 and 7. B, B'are provided with strip-type springs 4, 5 which are positioned and welded on the connecting devices 6, 7 and are then separated from the spring strips.

By the above steps, at the end of the line, connection devices 6 and 7 in the form of strips to which the connectors 12 and 13 and the springs 4 and 5 are attached are obtained, and then these are inserted into the case 1. Good.

The contents of the assembling process are as follows. Station of the turntable device 56
When the case 1 is sent to C by the vibrating ruler, the case is mounted on an appropriate mount on the turntable at this station.

When the table rotates, the loaded case moves to the station D. In the meantime, from said auxiliary lines A, B and A ', B', connecting devices 6, 7 with connectors and springs, still in strip form, are sent to stations D and E.

At stations D and E, a connector and a spring-loaded connecting device is grabbed, separated from the strip and subsequently pushed into the case 1.

At the station F, the PT is fed by the feeding device.
Insert the C wafer between the contacts (of springs 4 and 5),
The force of those contacts holds the wafer.

The thermal relay components assembled as described above are moved to the station G by the turntable. The lid 20 is being carried to the station G by the vibrating ruler, and the lid is put on the case and fitted therein.

The assembled thermal relay is discharged at the station H and automatically sent to the processing lines J and K. Lines J and K record and manage various data of the above-described devices and the like.

In the illustrated example, the lid is assembled to the case by mechanical engagement, but an adhesive, an ultrasonic welding method,
The lid could be fixed to the case by a thermal method.

Further, although the example of using the leaf spring for stopping the wafer has been described, the same can be done by using the coil spring.

Further, in terms of the electric circuit, the example in which the thermal relay is attached to the airtight connector (fuseite) has been described, but it may be attached to a terminal plate different from that.

It is also conceivable to protect the upper "quick connect" terminal with a canopy extended from the lid if required for some purposes or according to safety standards.

Although the present invention has been described above with reference to preferred embodiments, variations and modifications can be made without departing from the spirit of the invention.

[0040]

Since the resistor having the positive temperature coefficient of resistance is connected in series to the starting winding of the single-phase motor having the starting winding and the main winding, a sufficient starting current is supplied to the motor at the time of starting the motor. The current supplied to the start winding can be effectively limited after the start is completed. The resistor is held away from the container by a pair of contact devices, and the contact device has a conductive metal part of relatively high thermal resistance, so that heat from the resistor to the container and from the resistor to the container via the contact device. Conduction can be blocked. On the other hand, since the container is small and spherical, the thermal mass is small and the surface area to volume ratio is limited. Therefore,
Even for the entire starting relay, heat dissipation from the starting relay is minimized while the motor is rotating, thus improving the motor's operating efficiency. Can be prepared for startup.

[Brief description of drawings]

FIG. 1 is a view of a starting relay according to the present invention as seen from above with a lid removed.

2 is a cross-sectional view taken along line 2-2 of FIG. 1, with the lid fitted.

FIG. 3 is a cross-sectional view taken along the plane 3-3 of FIG. 1, with the lid still fitted.

FIG. 4 is a view from above of the lid partially shown in FIGS. 2 and 3;

5 is a sectional view taken along the line 5-5 in FIG.

6 is a view of the lid of FIG. 4 as seen from below.

7 is a sectional view taken along the line 7-7 in FIG.

FIG. 8 shows the electrical contact details of the starting relay according to the invention.

9A and 9B are views showing in detail one of springs for holding a thermo-responsive wafer (PTC) in the starting relay according to the present invention and contacting the same.

10 a, b and c show three circuit configurations for a starting relay according to the invention.

11a, 11b and 11c show various mechanical installation forms of the starting relay according to the invention.

FIG. 12 is a schematic view of an assembly line of a starting relay according to the present invention.

[Explanation of symbols]

1 Case 2 PTC Wafer 4, 5 Leaf Spring 6, 7 Electrical Connection Device 10, 10 ', 11, 11'"QuickConnect"
Mold terminals 12, 13 "Plug-on" connector 51 Airtight connector.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Luigi Trama             Biele del, Naples, Italy             Mimose, 8 (72) Inventor Giusetsu Penotaro             Pomiglianoda, Naples, Italy             Ruco 2, Via Del Trento

Claims (5)

[Claims] 1. A starting relay for a single-phase motor having a starting winding and a main winding, the relay having a positive temperature coefficient of resistance and rapidly increasing in resistivity when heated above a certain selected temperature level. A resistor wafer made of increasing material and a resilient conductive metal for electrically contacting opposite sides of the resistor wafer for connecting the resistor wafer in series with a motor starting winding. A pair of contact devices, and a container made of a heat insulating material, the container containing the resistor wafer and the contact device, the pair of contact devices, each of the container and both sides of the resistor wafer. And each of the pair of contact devices has at least a pair of wings, and the pair of wings gradually spread apart from each other toward the tip thereof, and the tip is separated from the resistor. Contacting the surface of the afer, the other ends of the wings of each contacting device are joined together and pointed to by a protrusion protruding from the inner wall of the container, most of the surface of the resistor wafer separating from the container, The container has a plurality of ribs on its inner wall, and is connected to the contact device to maintain a predetermined space between the resistor wafer and the container, and most of the surface of the resistor wafer is the resistor. Located away from the container to prevent direct heat transfer from the wafer to the container, the contacting device having at least some conductive metal of a relatively high thermal resistance material, and the contacting device from the resistor wafer. Blocks heat transfer to and from the container via the contact device and to the exterior of the container, and the container cooperates with the heat transfer characteristics of the contact device. In order to limit the thermal mass of the relay and the surface-to-body volume ratio of the container, they are generally small and spherical in shape and substantially enclose and tightly surround an essential part of the resistor wafer and the contact device, whereby The relay limits the current flowing in the starting winding of the motor after the start of the motor is completed, and minimizes heat radiation from the relay during the rotation of the motor in order to improve the operating efficiency of the motor, A motor starting relay in which the period until the relay becomes cold is minimized in order to enable a quick motor restart when the operation of the motor is interrupted. 2. The motor starting relay according to claim 1, wherein a material having a higher conductivity than that of the blade is attached to a tip portion of the blade. 3. The motor starting relay according to claim 1, wherein the blade has a cross section that becomes smaller toward the tip. 4. The motor starting relay according to claim 1, wherein the blade is provided with a slit for suppressing heat conduction. 5. The motor starting relay according to claim 1, wherein the blade is provided with a rib for increasing mechanical strength.