JP2669705B2 - Ware washing machine - Google Patents

Description

TECHNICAL FIELD The present invention relates to an article washer such as a dish washer.

[Prior Art] Generally, a washing machine such as a dishwasher has a water tank,
After a predetermined amount of water is stored in the water tank, the article to be washed that is used in the tank or held above the tank is circulated through a certain amount of water stored in the tank. Cleaning or rinsing is performed by use.

For example, in a dishwasher, after pouring a certain amount of water into the water storage tank to store it, put a detergent and spray water on the dishes in a fountain-like shape to wash the water, and then store the water in the water storage tank. After the water has been drained once, clean water is newly poured into the water tank, and this water is used for rinsing this time.

A water level sensor is provided on the inner wall of the water storage tank in order to store a predetermined amount of water in the water storage tank or to detect whether there is a predetermined water amount.

There are various types of sensors such as float type, pressure switch type, and electrode type.The float type is easily affected by ripples on the water surface, and the pressure switch type is difficult to detect accurately when the water level is low. There is.

The electrode type is suitable for a water level sensor of a ware washing machine because it does not have the above-mentioned drawbacks, but has the following drawbacks.

[Problems to be Solved by the Invention] That is, since the electrode-type water level sensor uses the conductivity of the stored water to flow an electric current and detects the water level, it depends on the conductivity of the water used. The amount of flowing current may change greatly, and the presence or absence of water may be erroneously detected.

For example, tap water in Japan has lower conductivity than tap water (hard water) in Europe and the United States, and if a water level sensor with low sensitivity is used for Europe and the United States, if water is injected into Japan, water will reach the sensor height. Despite being full, there is a risk of being mistakenly recognized as "no water" .To avoid this, if the sensitivity of the water level sensor is set high in advance, this time, for the following reasons, Sometimes, there is no water, but it may be falsely detected as "with water".

In other words, even if water is low in conductivity, such as tap water in Japan, once the detergent is added, the conductivity will increase significantly, so the foam due to this detergent water also shows considerable conductivity, and the height of the sensor increases. In some cases, even if the actual water level has not reached, current may flow due to the presence of bubbles, and it may be detected that there is water.

That is, in the electrode type water level sensor, the setting of the sensitivity is extremely delicate, and when detection is performed with a certain sensitivity, a detection error often occurs depending on use conditions.

 The present invention seeks to solve the above problems.

[Means for Solving the Problems] A ware washing machine according to the present invention inputs a signal from an electrode provided at a water level to be measured to a comparator, compares the signal with a reference voltage by the comparator, and outputs the signal from the comparator. A washing machine provided with a water level sensor for judging a water level from the first sensitivity of the water level sensor to the second sensitivity which is lower than the first sensitivity when detecting the water level. A control circuit is provided that automatically switches and determines "with water" when the comparator output shows good continuity in any sensitivity.

[Examples] The present invention will be described in detail below with reference to the drawings by using a dishwasher as an example.

FIG. 1 is a control circuit diagram of a water level detecting device, and FIG. 2 is a side sectional view of the entire dishwasher, in which a synthetic resin body case (2) integrally forming a washing tank (1) and a body case (2) A top cover that forms a door with a single plate-like body having a side cover (3) provided continuously on the rear side and both left and right sides and a grid-shaped ridge (4)... A lid cover (5) is provided, the lid cover (5) is extended on the upper surface and the front surface, and a rectangular box-shaped cleaning chamber (6) is formed by the cleaning tank (1) and the covers (3) and (5). At the same time, the lid cover (5) is openable and closable about the support shaft (7) at the rear edge of the upper surface, and the fence (9) into which dishes are placed via the guide rails (8) on both sides of the washing tank (1). To be installed in and out freely.

Also, a water supply port (10) is opened at the bottom of the washing tank (1),
A water supply valve (12) having a water supply solenoid (11) is provided at the water supply port (10), and the water supply port (10) is connected to the water supply hose (13) communicating with the water supply via the valve (12). The valve (12) is opened and closed to supply an appropriate amount of water into the cleaning tank (1).

 That is, the water level (L1) in FIG. 2 is the appropriate water level.

Further, a water storage tank (14) is formed at the bottom of the washing tank (1), and a water intake case (15) is fixed to the bottom of the tank (14). The tank (14) communicates through a lattice plate (16), and a heater (17) is provided inside the tank (14).

 (F) is a trash filter for food waste and the like.

A hollow water transmission shaft (1
8) is fixed, the fountain vane (20) having a plurality of jet nozzles (19) ... is rotatably attached to the upper end of the water guide shaft (18), and the water feed pump (22) including the water feed vane (21) is installed. It is installed on the lower surface side of the bottom of the cleaning tank (1), and the normal rotation discharge port (23) of the pump (22) is connected to the lower end of the water guide shaft (18).

In addition, a drain pipe (25) is connected to a reverse discharge port (24) of the pump (22), and a check valve body (27) and a secondary drain pipe (2) are connected to a drain hose (26) communicating with the sewer.
8) connect the drainage pipe (25) via
A water suction pipe (29) communicating with the water intake case (15) is connected to the water suction side of the water supply pump (22), and the water of the tank (14) is rotated forward by the forward rotation of the water supply pump (22). The water in the tank (14) is discharged from the reverse discharge port (24) to the sewer by the reverse rotation of the water supply pump (22) while the water is sent out from the cleaning chamber (23) into the cleaning chamber (6).

A control box (30) is mounted on the front side of the main body case (2). A power switch (31), a course selection switch, a drying selection switch, and a start switch are provided in the box (30). A light emitting diode for course display (35) is provided in the box (30),
Each diode (35) is selectively connected and lit in conjunction with each selection switch to display the selected contents of the selection switch. A microcomputer such as a cleaning circuit (51) described later is provided in the control box (30).

Furthermore, a water level sensor (60) having a ground electrode (56), a remaining water level electrode (57), a standard water level electrode (58), and an overflow water level electrode (59) is provided, and as shown in FIG. Is fixed to the side surface of the water storage tank (14) and, as shown in FIG. 1, the comparators (61) (62) (6
3) Connect the water level electrodes (57), (58), and (59) to the cleaning circuit (51) composed of a microcomputer via the 3), and apply a pulse waveform of AC voltage (current) between the ground electrode (56) and the ground electrode (56). The reference signal (a) is formed by the cleaning circuit (51), and the reference signal (a) from the circuit (51) is supplied to each water level electrode (57) (58).
(59) is applied via a condenser (64) .... The reference signal (a) necessary for water level detection is output from the washing circuit (51) only when the water level is detected, and the water storage tank (14)
Ground electrode (56) and each water level electrode (57) (58) through the water
(59) becomes conductive and the high level detection output of each comparator (61) (62) (63) detects the remaining water level, the standard water level and the overflow water level, and the buzzer (65) sounds when the overflow water level is detected. It is configured to give an alarm.

In the present invention, the reference signal (a) is applied to the electrodes (57) (58) (59) through the line (W1) and the resistance (R1) is applied to the electrodes (57) (58) (59).
Applied through (R2) and (R3). The reference voltage can be applied via separate resistors (R4) (R5) (R6), and the reference voltage can be changed.

That is, the same reference signal (a) is output or not output from the output terminal (P0) in a timely manner by a program in the microcomputer, but now the output terminal (P1)
Assuming that the reference voltage (A) is output from only the output terminal (P1), the comparator reference voltage becomes a relatively low voltage determined by the resistor (R4).
When the reference voltage (B) is also output from 2), the comparator reference voltage becomes slightly higher than the above-mentioned voltage (that is, the sensitivity becomes slightly higher and becomes medium), and the output terminal (P3) further outputs the reference voltage (C). ), The comparator reference voltage becomes even higher (highest sensitivity).

The above relationship is shown in FIG. 3 as a characteristic curve. The horizontal axis represents the sensitivity of the electrode, and the vertical axis represents the voltage. "Foam", "water",
Each level of "hard water" and "detergent water" indicates a level at which conduction starts.

In this figure, the sensitivity around 20 to 30 is the sensitivity based on the comparison signal (A) from only the output terminal (P1), and sufficient conduction can be obtained by tap water in Europe and the United States and water containing detergent, and almost even by tap water in Japan. This is the sensitivity at which good conduction is obtained.

The sensitivity around 50 to 60 is the sensitivity based on the comparison signal (B) from the output terminal (P2). The sensitivity is such that sufficient conductivity can be obtained with tap water in Japan, but the output becomes unstable depending on the bubbles.

In addition, the sensitivity around 80 to 90 is the sensitivity based on the comparison signal from the output terminal (P3). With this sensitivity, sufficient conduction can be obtained even with bubbles, and conduction can be obtained even with water with a particularly low ion concentration. To be

Here, the outputs from the comparators (61), (62) and (63) are illustrated in FIG. 4, and FIG. 4 (a) shows a state where conduction is sufficient, and FIG. 4 (b) Shows the case of insufficient power, and FIG. 4 (c) shows the case of no conduction. Since the comparators (61) (62) (63) have an inverting function, each output is an inverted signal with respect to the reference signal (a).

Of course, the sensitivity can be changed by changing the value of each resistor, and also changes when the number of electrodes is increased.

Output pulses (FIG. 4) from each of the comparators (61), (62), and (63) are taken into the cleaning circuit (51) in order to judge whether the continuity is good or not, and within a predetermined time. A counter (70) for counting the number of pulses is provided.

In addition, the counter (70) is provided with the electrode (57) according to the magnitude of the count value by the counter (70) and the change amount thereof.
(58) A judging circuit (71) for judging whether the position is water, foam or nothing is connected, and the buzzer (65) is output by the judging circuit (71).
Sounds or driving stops.

Next, the operation of the water amount sensor (60) will be described together with the operation of the dishwasher.

First, when one of the washing steps is selected by the course selection switch, the water supply valve (12) is opened by the water supply solenoid (11) to supply water, and a predetermined amount of water is supplied to the water storage tank (14). The water in the tank (14) is heated by the heater (17) which is continuously operated (the water level is indicated by the water level (L1) at this time), and the tank (14) is rotated by the forward rotation of the water supply pump (22). The water is delivered to the fountain vane (20), the water is ejected from the ejection nozzle (19) toward the upper part of the washing chamber (6), the vane (20) is rotated by the ejection force of the water, and the ejected water is turned into dishes. Wash off dirt by hitting.

In this step, the detergent is added after a predetermined amount of water is stored.

When the cleaning time has elapsed, the water supply pump (22) rotates in the reverse direction to discharge the dirty water in the tank (14), and the cleaning process ends.

The water level at the time of this drainage is detected by the remaining water level electrode (57).

The water supply valve (12) is used to start the rinsing work by moving to the next rinsing process after the washing process is completed.
Is opened and water is newly supplied, and the water supply pump (22) is rotated forward to perform the first rinsing. When the first rinsing operation is completed after a predetermined time, the tank (14) is operated in the same manner as the first rinsing operation.
The second rinsing operation and the third
A rinsing operation is performed, and when the rinsing operation is completed, the water in the tank (14) is completely discharged.

At the end of the rinsing process, the process shifts to the drying process, the heater (17) is intermittently operated, the water supply pump (22) is idly operated, and the cleaning chamber is moved through the forward discharge port (23) and the fountain blade (20). (6) The compressed air is sent into the inside of the table, and the tableware is dried by the air heated by the heater (17). When a certain period of time has passed, the drying process is finished.

FIG. 5 is a graph showing the change over time of the water level in the above operation.

That is, the washing step (E) and each rinsing step (F1)
Water supply and drainage are performed before and after (F2) and (F3) respectively, and the end point of water supply (T1) and the end point of drainage (T
In 2), the cleaning circuit (51) operates to detect the water level.

This detection operation is started by a timer preset in the cleaning circuit (51).

That is, the water level detection at the end of the water supply detects the presence or absence of water by the output from the comparator (62), and the water level detection at the end of the drainage is detected by the output from the comparator (61). The sensitivity of (58) is switched as follows to detect whether the conduction of the electrodes (57), (58) is truly due to water or to bubbles of detergent water.

That is, in general, the sensitivity of each electrode is set to be medium (50 to 60 in FIG. 3) so that it can be reliably detected even with Japanese tap water.

However, in this state, when the electrodes (57) and (58) are not in contact with water or bubbles at all, the comparator output is as shown in FIG. And, when both are in contact with bubbles, the result is as shown in FIG.

Therefore, lowering the sensitivity (20-30) and the electrode (57)
(58) In the case where conduction at the position is due to bubbles The number of pulses in the signal from the comparators (61) and (62) sharply increases as shown in FIG. 4 (b), and the conduction is due to bubbles. It turns out.

In other words, since the conductivity of water is higher than that of bubbles, even if it is Japanese tap water, water is the electrode (57) (58).
In the position, even if the sensitivity of the water level sensor is 20 to 30, the output continues to be in the state shown in Fig. 4 (a).

Even if the sensitivity is set to medium (50-60),
When water with a particularly low ion concentration (dashed line in Fig. 3) is used, the output of the comparator (62) is not obtained and even if there is water at the position of the electrode (58), it is erroneously determined that there is no water. In order to avoid such an error, the sensitivity is temporarily reduced from “medium” to “low”, and the above determination is made. Then, the sensitivity is increased to “high” (90 to 100). In this state, the output of the comparator (62) is detected, and if the output becomes high by this, it is determined that "there is water".

The operation to raise this sensitivity to "high" is when using water with a particularly low ionic sensitivity and before adding the detergent,
This is effective in detecting whether or not the first water supply in the cleaning step (E) reaches a predetermined amount of water. This is because the detergent has not yet been added at this point and the ion concentration remains low.

Next, the operation of the problem specific to the dishwasher will be described.

That is, the first rinse (F
Until 1), the state of water and bubbles in the tank (14) is such that a layer of bubbles (H) floats on the water surface as schematically shown in FIG. 6, but even in such a state. The water level can be accurately detected as follows.

That is, when the output from the comparator (61) of the electrode (57) is detected at a predetermined time when water should be drained,
If the state is as shown in FIG. 4 (a), it means that the water has not been drained properly, and in the prior art, the buzzer sounds immediately or the operation is stopped. Switching the electrode sensitivity from "medium" to "low", the cleaning circuit (51) determines the change in the signal output state at that time,
It detects whether the electrode (57) is really water, bubbles, or nothing.

If it is truly water, the buzzer will be activated or shut down for the first time, and if it is foam or there is no water at the electrode position, the water will be drained for the time being, so for the next rinse Move to water supply.

If the presence of bubbles is erroneously detected as "with water" while the sensitivity remains high, the next rinsing process (F1) is actually performed.
Although there is no problem even if you continue to do so, the operation will be stopped unnecessarily. If the presence of water is detected erroneously as "no water", the water supply amount will be changed to the valve (12) the next time water is supplied.
Since it's just setting the open timer, it will overflow.

Further, when the output from the comparator (62) of the electrode (58) is detected at a predetermined time when the water is to be filled to the standard water level, if the state of FIG. Since it is satisfied well, the conventional process immediately proceeds to the next step. In this embodiment, the electrode sensitivity is switched from “medium” to “low”, and the change in the output state of the signal at that time is changed. The cleaning circuit (51) judges and detects whether the position of the electrode (58) is truly water, bubbles, or nothing.

Then, if it is truly water, the process moves to the next step for the first time. If it is found that there is no bubble or there is no water at the position of the electrode (58), the buzzer sounds or the operation is stopped.

If the presence of bubbles is erroneously detected as "water present" while the sensitivity is still high, the amount of water in the next rinsing step will not be sufficient, and sufficient rinsing will not be possible. False detection of "no water" will cause extra buzzer operation or automatic stop of operation.

The present invention is, of course, applicable to a washing machine for articles other than a dishwasher.

[Effects of the Invention] As is clear from the above description, according to the ware washing machine according to the present invention, the water level can be adjusted even when it is difficult to detect the water level, such as when bubbles are floating on the water surface. It can be detected accurately and automatically stops even though it is normal, or the operation continues even if the water volume has not reached the predetermined level, and overflows in the next process or water shortage There is no hindrance that the washing effect is greatly reduced by operating as it is.

[Brief description of the drawings]

FIG. 1 is a control circuit diagram of a dishwasher according to the present invention, and FIG.
The figure is a side sectional view of the main body, FIG. 3 is a view showing characteristics of a water level sensor, FIG. 4 is a view showing an output from a comparator, FIG. 5 is a view showing a change in water level, FIG. 3 is a schematic diagram showing a relationship with. (1) Cleaning layer (51) Cleaning circuit (56) (57) (58) (59) Electrode (60) Water level sensor (a) Reference signal (P1 ) (P2) (P3) …… Output end, (70) …… Counter, (71) …… Judgment circuit

Claims (1)

(57) [Claims] An article provided with a water level sensor which inputs a signal from an electrode provided at a water level to be measured to a comparator, compares the signal with a reference voltage by the comparator, and determines a water level from an output of the comparator. A washing machine for automatically switching the sensitivity of the water level sensor from a high sensitivity first sensitivity to a low sensitivity second sensitivity with respect to the first sensitivity when detecting a water level; Comparator (61) (6
2) An article washing machine characterized by being provided with a control circuit (51) for determining "there is water" when the output (63) indicates good continuity.