JPH0447275B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention relates to a thermostat quality determination device using a bay-shaped bimetal as a temperature detection means.

b. Prior Art As is well known, in a thermostat, a movable contact is separated from a fixed contact by the reversal action of a bay-shaped bimetal formed by joining two metal plates with different coefficients of expansion, or the movable contact is separated from a fixed contact. Some devices are configured so that they are brought into contact with contacts, thereby causing a predetermined switching of the contacts.

FIG. 1 is a schematic diagram of a bimetal drive system in a thermostat, in which one end of a movable plate 1 made of a leaf spring or the like is fixed, and a movable contact 2 is attached to the other end. A fixed contact 3 is disposed at a position corresponding to the movable contact 2. Further, a convex portion 4 is formed in the middle portion of the movable plate 1, and a bay-shaped bimetal 5 is disposed corresponding to the convex portion 4.

When the bimetal 5 is curved downward as shown by the solid line in FIG.
When it comes into contact with, it is turned on. Furthermore, when the bimetal 5 is inverted as shown by the imaginary line in FIG. It is turned off by being separated from the

Regarding the reversing operation of the bimetal 5, as shown in _FIG.
and _L2 , and fast motion sections _L4 and _L5 in which the motion is extremely fast and instantaneously reverses. In actual product switching, fast motion sections _L4 and _L5 overlap each other, and _L3 is used, which is a section only for fast motion with reversal operations in both directions. bimetal 5
When it reverses upward from a downwardly curved state, it moves slowly and gradually in the slow motion section _L1 , and when it enters the section _L4 , it enters a fast interlocking state and instantaneously reverses. When reversing in the opposite direction, it moves slowly and gradually in the slow movement section _L2 , and when it enters the section _L5 , it enters the fast interlocking state and instantaneously reverses.

By the way, the parts precision of this bimetal 5 is poor, or the convex part 4 of the bimetal 5 and the movable plate 1
If the relative positional relationship between the movable plate 1 and the thermostat is poor (if the thermostat is defective), the bimetal 5 may come into contact with the convex portion 4 of the movable plate 1 within the slow movement section _L1 . In this case, while the movable plate 1 is gradually lifted, the bimetal 5 moves asymmetrically, so that the movable contact 2 swings slightly relative to the fixed contact 3. As a result, a chattering phenomenon occurs in which the movable contact 2 repeatedly connects and disconnects from the fixed contact at minute time intervals. If such a chattering phenomenon occurs, it will cause malfunction of the circuit, resulting in inaccurate temperature control, and will cause inconveniences such as accelerated wear of the movable contact 2 and fixed contact 3. . Therefore, thermostats that significantly cause the chattering phenomenon (thermostats whose contacts are switched in the slow movement section _L1 or _L2 ) must be excluded as defective products.

Conventionally, therefore, the reversal sound of the bimetal 5 is amplified electrically and listened to, and the quality of the thermostat is determined based on the synchronization state between the vibration of the meter connected to contacts 2 and 3 and the reversal sound. was. That is, if the reversal sound and the meter deflection are completely synchronized, it is determined to be a good product, and if there is a discrepancy between them, it is determined to be a defective product. In addition, when there is a deviation, there are cases where the reversal sound comes before and after the deflection of the meter, and in the former case, even if the bimetal 5 is reversed, the convex part 4 of the movable plate 1
In the latter case, the bimetal 5 comes into contact with the protrusion 4 in the slow movement section L ₁ and the contact point 2,
3 is opened while causing a chattering phenomenon.

c Problems to be Solved by the Invention However, since such a judgment method is a so-called sensory test based on the sense of sound, it requires a skilled inspector to make the judgment, which increases personnel costs.
The accuracy of the judgment was also not sufficient.

Furthermore, conventionally, there is a chattering measuring device that measures the chattering of contacts 2 and 3, but with this measuring device, chattering occurs even if contacts 2 and 3 are in the on state during operation within the slow movement section _L1 . In such cases, it was not possible to determine that the product was defective. In the case of a so-called snap drive system using bimetal 5, the fast motion section L ₃
If the temperature is set so that the contact switches _at do not have.

Therefore, it is a very serious problem that the contact switching occurs in the slow movement section _L1 , in other words, it is impossible to eliminate the possibility that the product is defective.

The present invention was invented in view of the above-mentioned circumstances, and its purpose is to automatically, objectively and accurately determine the acceptability of a thermostat, although it has a simple configuration. The purpose of the present invention is to provide a determination device that can obtain the desired results.

d. Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides a thermostat quality determination device having a bay-shaped bimetal as a temperature detection means. (B) reversal detection means for detecting reversal motion of a bay-shaped bimetal that instantaneously reverses direction in a non-contact manner; a first pulse signal output circuit that outputs a pulse signal; (C) a second pulse signal output circuit that outputs a pulse signal with a predetermined judgment reference time width when switching the contact that is switched in accordance with the reversal of the bimetal; and (D) a determination circuit that compares the pulse signals respectively output from the first and second pulse signal output circuits and determines whether there is a temporal overlap between them. and when the pulse signals respectively output from the first and second pulse signal output circuits overlap in time, switching of the contact point performs an instantaneous reversal operation of the bay-shaped bimetal. It is determined that the switching is being performed in the fast-moving section, and if these pulse signals do not overlap in time, it is determined that the switching of the contact is not being done in the fast-moving section, and based on this, I am trying to judge whether the thermostat is good or bad.

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 3 to 8.

As shown in FIG. 3, the quality determination device 7 of this example
a reversal detection means 8 for detecting reversal operation of the bay-shaped bimetal 5; a first pulse signal output circuit 9 for outputting a pulse signal of a predetermined width based on the reversal detection signal from the reversal detection means 8; A second pulse signal output circuit 10 that outputs a pulse signal of a predetermined width based on contact switching, and a determination circuit 12 that compares the pulse signals output from the first and second pulse signal output circuits 9 and 10, respectively. Each is equipped with In addition, in Fig. 3, contacts 2 and 3
As described above, these are the movable contacts and the fixed contacts that are brought into contact and separated as the bimetal 5 reverses.

In addition, in FIG. 3, for explaining the operation of this example,
A contact configuration that is in an open state (off state) at room temperature will be explained.

The above-mentioned reversal detection means 8 consists of an annular coil 15 and a pair of magnets 16 disposed near the coil 15.
The bimetal 5 is placed inside the magnet 16, and is configured so that the bimetal 5 is magnetized by a magnet 16. Under this condition, when the bimetal 5 is reversed, the magnetic flux crossing the annular coil 15 changes, so that an induced electromotive force is generated at both ends of the coil 15 as a reversal detection signal.

The first pulse signal output circuit 9 is composed of an amplification circuit 17, an absolute value circuit 18, a waveform shaping circuit 19, and a one shot circuit 20.
One pulse signal rising in response to the inversion detection signal and having a predetermined width is output from . That is, the inversion detection signal from the annular coil 15 is amplified by the amplification circuit 17,
The amplification circuit 17 outputs an amplification signal a as shown in FIG. 4A. Then, the amplified signal a is supplied to the absolute value circuit 18, and from this circuit 18 the amplified signal a is supplied to the fourth
An absolute value signal b as shown in FIG. B is output. Furthermore, the absolute value signal b is supplied to a waveform shaping circuit 19, which outputs a pulse signal c as shown in FIG. 4C. Then, this pulse signal c is supplied to a one-shot circuit 20, and from this circuit 20, the pulse signal c is supplied as shown in FIG. 4D.
One pulse signal d which rises in response to the rising edge of and has a predetermined reference time width Δt at a predetermined level is output.

On the other hand, the second pulse signal output circuit 10 is composed of a shot trigger circuit 22, an edge detection circuit 23, and a one shot circuit 24, and this circuit 10 outputs signals in synchronization with the switching of contacts 2 and 3 to the on state. One pulse signal having a rising edge, a predetermined level, and a predetermined width is output. That is, when the movable contact 2 comes into contact with the fixed contact 3 and is switched to the on state as the bimetal 5 is reversed, the Schmitt trigger circuit 2
2 is supplied with an ON signal e as shown in FIG. 5A. Note that FIG. 5A shows a case where chattering occurs during contact switching, and a chattering signal f is generated at the rising edge of the ON signal e.

An output signal g corresponding to the on signal e is sent from the shot trigger circuit 22 to the edge detection circuit 23.
The edge detection circuit 23 outputs a pulse signal h that rises in response to the rising edge of the output signal g. This pulse signal h is then supplied to the one shot circuit 24, which rises in response to the rising edge of the pulse signal h and outputs one pulse signal i having a predetermined level and a predetermined reference time width Δt. be done.

Therefore, the first and second pulse signal output circuits 9 and 10 output a pulse signal d corresponding to the inversion of the bimetal 5 and a pulse signal i corresponding to the switching of the contact, but these pulse signals d , i are designed to be equal in level and pulse width to each other.

Further, the first and second pulse signal output circuits 9,
The pulse signals d and i from 10 are supplied to the input terminals of an AND circuit 26 and an OR circuit 27, respectively, as shown in FIG. Note that this determination circuit 12
The pulse signals d and i are compared with each other based on the pulse signals d and i from the pulse signal output circuits 9 and 10 and the output signals from the AND circuit 26 and the OR circuit 27, thereby automatically determining the quality. This is a circuit that performs this purpose.

As shown in FIG. 6, when the rising edges of pulse signal d (inversion detection signal) and pulse signal i (contact switching signal) match, the matching signal j (pulse signal) is detected by the comparison circuit ( (not shown) to an output line 29. In this case,
It is determined that the contact switching operation has been performed in the fast motion section _L4 of the bimetal 5, and a display device not shown to that effect is displayed. This allows the inspector to confirm that the thermostat being inspected is of good quality. Furthermore, as shown in Fig. 7, even if the pulse signals d and i deviate by a small time interval, if a portion of them overlaps, a good product can be determined based on the coincidence signal j with a narrow pulse width. A message to that effect is displayed.

On the other hand, as shown in FIG.
If there is no overlap due to a large time interval deviation, no coincidence signals j, j' are output.

In this case, it is determined that the switching of the switching point is not performed in the fast motion section of the bimetal 5, and the determination circuit 1
Based on the output signal from the output line 30 of No. 2, a display to that effect is displayed on a display device (not shown). This allows the inspector to confirm that the product is in a state where a noticeable chattering phenomenon occurs due to the contact switching being performed in the slow movement section _L1 of the bimetal, and to treat the thermostat under inspection as a defective product. can be determined.

In this example, the output of the amplifying circuit 17 is supplied to a monitoring amplifying circuit 31 via a variable resistor R, so that the inverted sound of the bimetal 5 can be monitored using earphones, headphones, or the like.

Further, in the above embodiment, the thermostat is judged to be good or bad based on the pulse signal h that rises in synchronization with the switching of the contacts 2 and 3 to the on state. It is possible to determine whether the thermostat is good or bad even when it is switched to the OFF state. That is, in this case, as shown in FIG. 9, when the contact output (on signal e) is turned off, the output signal g is also turned off, and the edge detection circuit 23 outputs the output signal g.
A rising pulse signal corresponding to the falling edge of
h′ is output. And one shot circuit 24
One pulse signal i' rising corresponding to the rising edge of the pulse signal h' and having a predetermined level and a predetermined pulse width Δt is output. By comparing this pulse signal i' with the pulse signal d output from the one-shot circuit 20 as the bimetal 5 is inverted, it is possible to automatically determine whether the switching to the OFF state is good or bad. can.

According to the device 7 for determining whether the thermostat is good or bad, although the circuit is simple and can be configured with relatively few (more than ten) ICs, the bimetal 5
It is possible to automatically, objectively and accurately determine whether or not the product is a defective product in which the contacts are switched during the slow movement section.

Note that the first and second pulse signal output circuits 9,
By changing the pulse width Δt of the pulse signals d and i from 10, it is possible to change the allowable amount of determination.

Furthermore, in the above embodiment, the overlapping portion between the pulse signals d and i was detected to compare them, but the time interval between the rise or fall of these pulse signals d and i is detected, The determination may be made based on this time interval. Alternatively, the determination may be made by calculating the difference between the pulse signals d and i.

e Effects of the Invention As described above, the present invention provides a pulse signal reversal detection signal outputted as a result of reversal of a bay-shaped bimetal,
Since the thermostat is automatically judged to be good or bad by comparing the output pulse signal with the contact switching signal as the contact switches, it does not require a specially skilled inspector and is extremely simple. It is possible to easily, objectively and accurately judge whether a thermostat is good or bad.

It is also possible to discover defective products in which contact switching occurs in the slow movement section of the bimetal, and to prevent defective products from leaving the market.

In addition, since the reversal movement of the bimetal is detected externally using a non-contact method, no restraining force (load) is applied to the bimetal during pass/fail judgment. The thermostat as a product can be evaluated under the conditions of actual use.
Therefore, the product inspection of the thermostat can be carried out efficiently under the same conditions as when it is used, which in turn makes it possible to reduce the cost of the product.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view for explaining the contact/separation operation between the movable contact and the fixed contact as the bimetal is reversed, Fig. 2 is a schematic diagram showing the operating section of the bimetal, and Fig. 3 is a schematic cross-sectional view for explaining the contact/separation operation between the movable contact and the fixed contact as the bimetal is reversed. A block diagram showing the configuration of a thermostat quality determination device according to an embodiment, FIG. 4 is a waveform diagram for explaining the operation of the pulse signal output circuit of FIG. 1, and FIG. 5 is a waveform diagram for explaining the operation of the pulse signal output circuit of FIG. Figures 6 and 7 are waveform diagrams for explaining the operation of the pulse signal output circuit in No. 2, Figures 6 and 7 are waveform diagrams for explaining the operation of the determination circuit when the thermostat is good, and Figure 8 is a waveform diagram for explaining the operation of the determination circuit when the thermostat is good. FIG. 9 is a waveform diagram illustrating the operation of the determination circuit in the case where the tattoo is defective. FIG. 9 is a waveform diagram illustrating the operation of the second pulse signal output circuit when switching to the off state. 5... Bay-shaped bimetal, 7... Quality determination device, 8... Reversal detection means, 9... First pulse signal output circuit, 10... Second pulse signal output circuit, 12... Judgment circuit, 15... Annular coil, 1
5a...Hollow part, 16...Magnet.

Claims (1)

[Scope of Claims] 1. In a thermostat quality determination device having a bay-shaped bimetal as a temperature detection means, (A) a reversing operation of the bay-shaped bimetal that instantaneously reverses the warping direction in response to a change in ambient temperature; (B) a first pulse signal output circuit that outputs a pulse signal having a predetermined determination reference time width based on the reversal detection signal from the reversal detection means; (C) a second pulse signal output circuit that outputs a pulse signal with a predetermined judgment reference time width when switching the contact that is switched in accordance with the reversal of the bimetal; (D) the first and second pulse signals; a determination circuit that compares the pulse signals respectively output from the output circuits and determines whether or not there is a temporal overlap between them; and the first and second pulse signal outputs. If the pulse signals outputted from the circuits overlap in time, it is determined that the switching of the contacts is performed in a fast motion section where the bay-shaped bimetal instantaneously reverses, and these signals are If the pulse signals of the thermostat do not overlap in time, it is determined that the switching of the contact point is not performed in the fast movement section, and the acceptability of the thermostat is determined based on this. A thermostat quality determination device.