EP1183985B1 - Valve for a dishwasher with a movable closure device - Google Patents

Description

The invention relates to a valve for a dishwasher with a closure element movably arranged in a cavity of a valve body (US Pat. FR-A-2 789 451 ).

In the DE 197 10 644 A1 a valve for a dishwasher is described in which the valve body encloses a cavity in which a movably arranged valve ball is enclosed. The inlet side of the valve is connected to a circulation pump and the outlet side to a spray arm of a washing compartment. Without fluid flow, the valve ball assumes a rest position in the cavity in which it can be fixed by an actuator, so that despite the onset of flow the valve ball is held in the rest position. By loosening the actuating element, the valve ball is entrained by the liquid flow and pressed against the outlet, so that it is completely closed. In this valve, however, it may happen that the ball does not return to the rest position with only short interruption phases of the circulation pump through the return line from the liquid line. As a result, after resuming the operation of the circulation pump, the ball is in turn forced to the outlet, so that it closes it. Since the ball has not returned to its rest position, can not be held in this position by the actuator, the ball, although in the corresponding rinsing phase, a liquid flow through the outlet would be desirable. Furthermore, jamming of the ball in the rest position or at another position of the cavity can not be detected.

The EP 0 237 994 B1 discloses a reversing valve in which a ball is enclosed in a cavity. The cavity is connected on the input side to a circulation pump and on the output side through a first outlet with a first line to a lower spray arm and through a second outlet with a second line to an upper spray arm. When the pump is switched off for a long time, the valve ball is in a rest position, from which it is raised after closing the pump to the second outlet and closes it. When the pump is switched off for a short time, the valve ball is urged away from the second outlet in the direction of the first outlet by the return fluid from the second conduit. The valve ball remains near the first outlet as long as the liquid flows out of the second line. If the circulating pump is switched on again within this period, the ball is pressed by the liquid flow in the cavity to the first outlet and closes it. Thus, a valve with two switch positions is provided in which the liquid flow can be discharged either through the first or through the second outlet. By a leakage fluid bypass from the cavity to the second outlet ensures that even in the position in which the valve ball closes the second outlet, a small amount of liquid flows into the second line to the switching described by the back-flowing rinsing liquid from the second line enable. A Control of the actual switching position is not possible.

On this basis, it is the object of the invention to propose a valve for a dishwasher, in which the switching position of the valve can be detected.

According to the invention, this object is achieved with the features of claim 1.

According to claim 1, a valve for a dishwasher is provided, in which a valve body encloses a cavity in which a movably arranged closing element is enclosed. Through a feed, a liquid is supplied into the cavity and discharged through at least one outlet (hereinafter referred to as a first outlet) into a liquid line (hereinafter referred to as first liquid line). The first outlet can be blocked by the closing element. Furthermore, at least one sensor is arranged on the valve body, with which the closing element can be detected at a first position in the cavity.

The position of the sensor is at a passage position of the closing element, which occupies the closing element between the closed position at the first outlet and a rest position of the closing element.

A sensor for detecting the position is regularly an optical sensor, a conductivity sensor, an ultrasonic sensor, a mechanical motion sensor, etc. With the conductivity sensor, e.g. be detected that the conductivity drops when positioning the closing element at the sensor position when the closing element is insulating, or that the conductivity increases when the closing element is conductive.

By the sensor can be detected, whether the closing element occupies a certain position or it happens at a certain position. This can be done by evaluating the signals the functioning of the switching over of the valve is checked by the sensor in a detection device and if necessary a triggering of the valve to correct the switching position is carried out. Such a malfunction could occur, for example, if the switching behavior of the valve is subject to temporal fluctuations or if the closing element is jammed in the cavity and therefore does not assume the desired position.

When the position of the sensor is the closing position of the closing element at the first outlet, the blocking of the liquid flow through the first outlet can be detected. The detection signal is permanently applied during the closing time.

An example of the application is from the DE 197 10 644 A1 known valve. By placing the sensor in the through position, the closing element is only detected when it changes between the two positions. Since a change in the position of the closing element only takes place when a switching state has previously been changed in the dishwasher, it can be detected by waiting for the signal from the first sensor, whether the closing element has actually carried out the switching of the valve position. Thus, only one sensor is required to detect both positions.

In another embodiment, another outlet, hereinafter referred to as the second outlet, connects a second conduit to the cavity and is also lockable by the closure member. Through the first sensor can then be detected switching between the closed position of the closing element at the first outlet and the closed position at the second outlet and vice versa.

In an advantageous embodiment, a LeckströmungsEinrichtung is arranged at the first outlet, which causes that when the first outlet is blocked a reduced flow of liquid flows into the first liquid line and keeps them filled. In this valve, a switching between the blocking of the first outlet and the second outlet can be achieved, as for example from the EP 0 237 994 B1 is known.

By arranging a second sensor at a second position, independently two different closed positions of the closing element or passage positions of the closing element can be detected.

In a particularly advantageous embodiment, the first or second position of the sensor is a dynamic equilibrium position of the closing element, in which the closing element temporarily lingers during a Rückströmphase the liquids from the first and second liquid line. The residence time of the closing element in this position is longer in comparison to other passage positions, so that the closing element can be reliably detected at this position. Due to the longer residence time of the closing element in this position further simplifies a control of the switching position of the valve, since there is a longer time window to switch the valve so that the first or the second outlet is blocked. At this position, for example, by only one sensor a safe switching of the valve can be achieved.

By providing another sensor e.g. At a passage position, the reaction of the valve can be detected after a change in the dishwasher control and optionally caused an error correction control.

In a further embodiment of the valve, a third outlet is arranged between the first outlet and the second outlet, which is also lockable by the closing element. Through the third outlet, the rinsing liquid may e.g. be discharged into a third line or directly from the valve in a washing compartment of the dishwasher. The third line may e.g. be connected to a Spülmaschinensumpf, an intake of a circulating pump or an additional spray arm.

When the closing element closes the third outlet, the closing element is captured in this position by the pressure difference between the cavity of the valve and the outlet side of the third outlet, so that both the first and the second outlet are released.

By arranging one of the two sensors, e.g. at the passage position between the closed position at the first outlet and the closed position at the third outlet and a sensor in the dynamic equilibrium position, all three switching positions of the valve can be reliably detected.

In a further refinement, the sensor or the sensors are optical sensors which can detect the closing element without contact and thus without wear. Particularly advantageous is the simultaneous use of the optical sensor as a turbidity sensor. Thus, the sensor assumes a dual function by, on the one hand, a position of the Closing element is detected and on the other hand, the contamination of the rinsing liquid is detected in the dishwasher.

The advantage here is the arrangement of the sensor in a passage position of the closing or in the dynamic equilibrium position of the closing, since at these positions, the closing element is detected only briefly and in the remaining time the sensor can detect the turbidity of the washing liquid. Haze is in these positions of the closing element, e.g. characterized in that the passage of the closing element is detected by a short-term strong change of the signal, while the degree of contamination over time averaging is recognized as a long-term change of the signal.

In this case, if two sensors are arranged at a first position in the connecting line from the inlet to the first outlet and in a second position from the inlet to the second outlet or in the vicinity thereof, the degree of contamination of the flushing liquid flowing past can be detected in any case. If e.g. Only the first or only the second outlet are released, is thus prevented that a dirt particles in the dead volume at the flow-free position affects the signal and thus does not reflect the degree of turbidity properly.

The turbidity sensor may be a conductivity sensor that detects the change in conductivity due to contamination. Preferably, an optical sensor is used. The optical sensor may be formed as a reflection sensor, which detects either the reflection of the dirt particles in the rinsing liquid or the closing element or the reflection of the optical signal at the opposite Inner wall of the cavity, which reflects the signal back to the sensor. When using the reflection sensor, the sensor only has to be integrated on one side of the valve body. Alternatively, a photocell may be used, which is disposed at opposite positions on the inner wall of the cavity, wherein the change in the light intensity is detected when passing through the washing liquid in the cavity.

With reference to figures, embodiments of the invention will be explained.

Fig. 1

eine schematische Darstellung eines Spülflüssigkeitskreislaufs einer Geschirrspülmaschine,

Fig. 2A

ein Umschaltventil mit einer Kugel in verschiedenen Stellungen im Hohlraum des Umschaltventils,

Fig. 2B

das Umschaltventil von Fig. 2A mit einer weiteren Stellung der Kugel und

Fig. 3

die Anordnung von Lichtschranken am Ventilgehäuse in Draufsicht.

Show it:

Fig. 1

a schematic representation of a rinsing liquid circuit of a dishwasher,

Fig. 2A

a switching valve with a ball in different positions in the cavity of the switching valve,

Fig. 2B

the switching valve of Fig. 2A with another position of the ball and

Fig. 3

the arrangement of photocells on the valve housing in plan view.

Fig. 1 shows a schematic representation of the Spülflüssigkeitskreislaufs in a dishwasher. In a washing compartment 1 of the dishwasher, an upper spray arm 2 and a lower spray arm 3 for applying the washware stored in dishwashing baskets 4 are arranged with rinsing liquid. The spray liquid sprayed by the spray arms 2, 3 is collected at the bottom of the washing compartment 1 in the dishwasher sump 5. The collected rinsing liquid is via an inlet of a circulating pump 6 sucked and fed through a connecting line 7 to a switching valve 8.

From the switching valve 8, the rinsing fluid passes through a first purge line 9 to the upper spray arm 2 and through a second purge line 10 to the lower spray arm 3. Furthermore, from the switching valve 8 branches off a bypass line 11, which opens into the inlet to the circulation pump 6.

In Fig. 2A the switching valve 8 is shown in a schematic, enlarged view. A valve body 12 of the switching valve 8 encloses a cavity 13 in which a ball 14 is enclosed.

As in Fig. 2A shown, the valve body 12 has a first opening 15 on the right side, which connects the cavity 13 with the first purge line 9. On the left side, the valve body 12 has a second opening 16, which connects the cavity 13 with the second purge line 10. Furthermore, a bypass opening 17 is arranged on the upper side of the valve body 12, which connects the cavity 13 with the bypass line 11. In the cavity 13, a flow guide 18 is formed, which directs the flow from the connecting line 7 flushing fluid flow to the first and / or second opening 15, 16.

The movably mounted in the cavity 13 ball 14 is guided in the cavity 13 by lower guide edges 19 and upper guide edges 20. The guide edges 19, 20 allow the ball 14 to move along the axis between the first and second openings 15, 16, wherein a lateral clearance of the ball relative to the leading edges is made possible by a guide clearance in order to avoid jamming of the ball.

The switching valve 8 allows three closed positions of the ball 14, which in FIGS. 2A and 2B with I, II and III are designated. The geometric relationships of the relative positions of the ball are only schematically reproduced to explain the switching sequences.

In the position I, the ball 14 closes the first opening 15, so that the introduced rinsing liquid exits substantially through the second opening 16. A small amount of bypass fluid also exits through the bypass port 17. A leakage flow device, not shown, causes despite the closing of the first opening 15, a small amount of leakage liquid enters the first line 9. By this leakage liquid flow ensures that during operation of the circulation pump 6 always the liquid column in the first line 9 to the upper spray arm 2 increases.

In position II, the in Fig. 2A is shown by a dashed ball, the ball 14 closes the second opening 16 so that the rinsing liquid exits substantially through the first outlet 15 and slightly through the bypass opening 17.

In the position III, which is also shown by a dashed ball, the ball 14 closes the bypass opening 17, so that the rinsing liquid flow is divided on the guide body 18 and passes through both the first opening 15 and through the second opening 16. In this case, both the upper spray arm 2 and the lower spray arm 3 are supplied with rinsing liquid. In the other cases, flushing liquid is supplied to either the upper spray arm 2 or the lower spray arm 3, respectively.

In the positions I, II and III, the ball 14 is held in the lines 9, 10 and 11 due to the pressure difference between the pressure of the rinsing liquid in the cavity 13 and the output side pressure of the rinsing liquid.

The following is a brief description of the switching possibilities for the changeover valve 8. First, it is assumed that the circulation pump 6 was not operated for a long time (for example, 2 seconds). In this state, the rinsing liquid from the first and second purge line 9, 10 and from the bypass line 11 has expired through the circulation pump 6 or there are no backflows more present in the cavity 13. In this state, the ball 14 rolls along the lower guide edges 19 in the rest position, which corresponds to the closed position I of the ball 14 or at least in their immediate vicinity.

If the circulating pump 6 is switched on from this state, the ball 14 is forced into the position I due to the flow, in which it closes the first opening 15. However, rinsing liquid flows into the first rinsing line 9 through the leak liquid device and fills it with rinsing liquid.

If the circulating pump 6 is now turned off, then the ball 14 moves through the backflow of the rinsing liquid from the first rinse line 9 from the position I via the position III in the direction of position II. During this movement, the circulation pump 6 is turned on when the ball in the Near the position III, the ball is sucked due to the pressure difference of the rinsing liquid in the cavity and the pressure in the bypass line 11 to the bypass opening 17 and held there.

If during this oblique upward movement of the ball 14, the pump 6 is not yet turned on, the ball moves over the position III to near the position II. Is the ball near the position II and the circulation pump 6 is turned on, the ball closes the second opening 16.

However, if the circulation pump 6 is not turned on at the time of the ball position II, then the ball returns after the drainage of the rinsing liquids from the first and second rinse lines 9, 10 to the rest position, from where the switching cycle can be repeated.

When returning the ball from position II to position I, the circulation pump 6 can also be turned on, so that it is pressed again in the position III against the bypass opening 17. Thus, there are two time windows in which the ball passes the position III and by switching on the circulation pump 6, a valve position is achieved in which both spray arms are supplied with rinsing liquid.

Fig. 2B shows a position IV of the ball, which occupies this a temporary time. After switching off the circulation pump 6 in the position I of the ball, this moves through the backflow of the rinsing liquid from the first rinse line 9 almost to the position II. Due to the sufficient drainage of the rinsing liquid by the circulation pump 6 but simultaneously rinsing liquid from the second rinse line 10 back. As a result, the ball is displaced from the position II to the position IV by the action of both return flows from the lines 9, 10. In this position, the ball is held as long as liquid flows back from both rinsing lines. In this state, therefore, the ball comes to a temporary halt before they after derivation of Liquids from the purge lines return to their rest position at or near position I due to the potential energy via the lower leading edge 19.

In the FIGS. 2A and 2B are indicated by the positions A, B and C positions in which the ball is detected by light barriers. The photocells are described in more detail below.

If the ball 14 comes with its cross section in the range of one of the light barriers, then the light is shaded and the received signal is reduced accordingly. The light barriers arranged at these positions also measure the turbidity of the rinsing liquid. With increasing contamination of the washing liquid by dirt residues from the items to be washed, the washing liquid becomes cloudy and the signal received by the light barrier gradually weakens over time. This signal can be used to refill fresh rinse liquid if the rinse liquid is heavily contaminated or if necessary, replace it with fresh water from a fresh water supply line.

In the illustrated positions A, B and C, the ball 14 dwells only during the switching phases of the valve 8, so that the light signal is not constantly interrupted by the ball. Thus, the averaged over a long time measurement of the turbidity of the rinsing liquid undisturbed by the short-term spherical signal (about 1/10 s at A and B) can be made. In contrast, a short-term total shadowing of the receiver of the light barrier indicates that the ball has passed a passing position.

For better reproducibility of the time and the duration of the position of the ball in position IV may at the second opening 16 also a leakage flow device be provided. This causes in the closed position II, that a defined amount of liquid in the second purge line 10 is present. Thereby, the ball 14 is held in the position IV in a repeatable manner by the backflow of the liquid from the first and second purge lines 9, 10.

In the description of the following examples of switching cycles, it is assumed that the circulation pump 6 was initially in operation for a long time (over about 2 s) and the first purge line 9 and possibly the second purge line 10 are filled with rinsing liquid.

Switching cycle I

The switching cycle from the closed position I can be controlled as follows:

I.a)

In the first embodiment of the arrangement of the light barriers at the positions A and B ( Fig. 2A ), the change-over valve can be switched as follows:

The ball is in the closed position I and the circulation pump 6 is turned off. Thereupon, at position A, the change of the position of the ball from I to III is detected by the light barrier. If the circulation pump is set immediately afterwards, the ball can be held in position III.

If, after the signal from the position A, the light barrier signal is detected from the position B, the ball assumes a position in the vicinity of the position II and turning on the circulation pump 6 keeps the ball in the closed position II.

If, after the light barrier signals from position A and position B, the pump is not adjusted and the signal is again from position B, the ball can be held again at position III by switching on the circulating pump immediately thereafter.

If after the signals from the positions A and B again the signal from the position A, the ball has assumed its rest position and by turning on the circulation pump, the first opening 15 can be closed (closed position I).

I.b)

In the second embodiment with the arrangement of the photoelectric sensors in the positions A and C according to Fig. 2B can the changeover valve 8 be switched as follows:

Starting position is again the position I and the pump is switched off. If, after switching off, the signal is received from position A, the ball can be held in position III by switching on the pump.

If the signal from position C, in which the ball is in position IV, is detected for a slightly longer dwell time, the ball can be forced into position II by switching on the circulating pump 6 during the dark phase in position C.

If it is detected that the signal is bright again in position C, ie the ball moves from position IV to position III, the ball can be held in position III by switching on the pump.

Is after the dark phase, ie after the light barrier at the position C, the signal from the Received light barrier at the position A, the rest position of the ball is reached and by switching on the circulation pump 6, the position I of the ball can be achieved.

The advantage of the arrangement of the photocells according to Fig. 2B lies in the fact that the photocell can detect the dark signal in the position C for a longer window of time, so that in this position by switching on the pump, the position II can be safely approached. On the other hand, if the ball moves out of position IV, it rolls back due to the potential energy at the lower leading edge 19 alone, which is slower than if the ball were driven by the return currents. As a result, the position III when rolling back the ball can also be controlled safely. Thus, the switching is less critical to switch-on delays, aging phenomena of the pump or other disturbances of the currents and the switching of the switching valve 8 is reliable.

Switching cycle II

The switching cycle from the closed position II can be controlled as follows:

II.a)

In the embodiment of Fig. 2A the light barrier signal is detected by the position B after switching off the circulation pump. If the circulation pump is started immediately thereafter, the closed position III is reached.

If the light barrier signal from the position A is detected after the light barrier signal from the position B, the ball can be pushed into the closed position I by starting the circulation pump after a short waiting time.

II.b)

In the embodiment of Fig. 2B the light barrier signal is detected from the position C after switching off the circulation pump. If the circulating pump is started a short time after the light barrier signal has gone out from position C, the ball can be held in the closed position III.

If the light barrier signal from the position A is detected after the light barrier signal from the position C, the ball can be urged into the closed position I by starting the circulation pump after a short waiting time.

Switching cycle III

The switching cycle from the closed position III can be controlled as follows:

III.a)

In the embodiment of Fig. 2A the light barrier signal is detected by the position B after switching off the circulation pump. If the circulation pump is started immediately thereafter, the closed position II is reached.

If this signal is detected a second time after the light barrier signal from the position B and then the light barrier signal from the position A, so the ball can be urged into the closed position I by starting the circulation pump after a short waiting time.

IIIb)

In the embodiment of Fig. 2B the light barrier signal is detected from the position C after switching off the circulation pump. When the circulation pump is started as long as this signal is present, the closed position II is reached.

If the light barrier signal from the position A is detected after the light barrier signal from the position C, the ball can be urged into the closed position I by starting the circulation pump after a short waiting time.

Fig. 3 shows a top plan view of the switching valve 8 to which a light barrier 21 for detecting the position A and a light barrier 22 for detecting the position B and C are arranged. At the in Fig. 3 The above-illustrated side surface of the valve body 12, the LEDs of the photoelectric sensors 21, 22 are installed, while on the side surface of the valve body 12 shown below, the receivers are installed. The light barriers 21, 22 are connected to an evaluation unit 23, in which the signals are detected and evaluated. The evaluated signals are supplied to the monitoring and control of a control circuit, not shown, of the dishwasher.

LIST OF REFERENCE NUMBERS

1:

Wash cabinet

2:

upper spray arm

3:

lower spray arm

4:

dish rack

5:

Dishwasher swamp

6:

circulating pump

7:

connecting line

8th:

switching valve

9:

first flushing line

10:

second purge line

11:

Bypass line

12:

valve body

13:

cavity

14:

Bullet

15:

first opening

16:

second opening

17:

Bypass opening

18:

flow guide

19:

lower leading edge

20:

upper leading edge

21:

Photocell at position A

22:

Photocell at position B

23:

evaluation

Claims (11)

1. Valve for a dishwasher having a valve body (12), which encloses a cavity (13), an inlet (7) for a liquid feed into the cavity (13), an outlet (15), which connects a liquid pipe (9) to the cavity (13), a closure element (14) arranged to be movable in the cavity (13) and by means of which the outlet (15) can be shut, wherein at least one sensor (21) is arranged on the valve body (12) and with which the closure element (14) can be detected at least at a first position in the cavity (13), characterised in that the first position of the sensor (21) is a transit position (A, B, C) of the closure element (14) between a closed position (I) on the outlet (15) and a rest position of the closure element (14).
2. Valve according to claim 1, characterised by a further outlet (16), which connects a further pipe (10) to the cavity (13), wherein the further outlet (16) can be shut by the closure element (14).
3. Valve according to claim 2, characterised by a leakage-flow device, through which a reduced liquid flow can be introduced into the liquid pipe (9) if the closure element (14) shuts the outlet (15).
4. Valve according to claim 2 or 3, characterised by a further sensor (22) arranged on the valve body (12) and with which the closure element (14) can be detected at a second position in the cavity (13).
5. Valve according to claim 4, characterised in that the second position of the sensor (22) is the closed position (II) of the closure element (14) at the further outlet (16).
6. Valve according to claim 4, characterised in that the second position of the sensor (22) is a transit position (B, C) of the closure element (14) between the further outlet (16) and a rest position and/or the closed position (I) of the closure element (14) at the outlet (15).
7. Valve according to claim 4, characterised in that the first or second position of the sensor (21, 22) is a dynamic equilibrium position (IV) of the closure element (14), in which the closure element (14) is kept temporarily during a back-flow phase of the liquids from the liquid pipe (9) and the further liquid pipe (10).
8. Valve according to one of claims 2 to 7, characterised in that at least one third outlet (17) is arranged between the outlet (15) and the further outlet (16), wherein the third outlet (17) can be shut by the closure element (14).
9. Valve according to one of the preceding claims, characterised in that the at least one sensor (21, 22) is an optical sensor.
10. Valve according to one of the preceding claims, characterised in that the at least one sensor (21, 22) is a turbidity sensor.
11. Valve according to claim 9 or 10, characterised in that the at least one sensor (21, 22) is a reflection sensor or a light barrier.

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