WO2008053309A1

WO2008053309A1 - Dishwasher and dish washing method

Info

Publication number: WO2008053309A1
Application number: PCT/IB2007/003244
Authority: WO
Inventors: Régis THIBON
Original assignee: Premark Feg L.L.C.
Priority date: 2006-10-30
Filing date: 2007-10-29
Publication date: 2008-05-08
Also published as: FR2907656B1; EP2083667A1; CA2667967A1; AU2007315893A1; FR2907656A1; CN101594814A

Abstract

The invention relates to a dishwasher (1) comprising at least a washing station (2), a rinsing station (3) and a drying station (4) defining a tunnel (5), a conveyor (6) being provided in said tunnel (5) and being capable of transferring items at least from the rinsing station (3) to the drying station (4), the drying station (4) comprising means for circulating air towards a drying area (10) for the items to be dried and means for heating the circulating air, and detection means (15) for detecting the presence of items to be dried and capable of modifying the temperature set-point of the drying air.

Description

Dishwashing machine and method of washing dishes.

The present invention relates to the field of dishwashing in a machine with a large flow rate, in particular of the tunnel type. The present invention relates more particularly to drying the dishes after washing and rinsing.

Establishments serving a large number of meals are usually equipped with washing facilities for the dishes previously arranged in lockers. The bins are deposited on a conveyor and advance entering the washing machine with a washing step, then a rinsing step and finally a drying step. At the exit of the washing machine, the dishes are dry and can be reused. The bins are then removed from the carrier.

WO 2005/032324 discloses a method of drying objects comprising disposing the objects on a support and generating a forced flow of gas and directing it toward the objects to cause drying.

The Applicant has found that this type of process does not ensure satisfactory drying. The invention aims to remedy the disadvantages mentioned above.

The invention provides an efficient drying method and device, energy saving and controlled cost of operation.

The washing machine comprises at least one washing station, a rinsing station and a drying station forming a tunnel, and a conveyor arranged in the tunnel and able to move objects from one station to another. The drying station comprises means for circulating air to a drying zone of the objects to be dried and means for heating the air as a function of a temperature set point. The washing machine comprises means for detecting the presence of objects to be dried able to modify the temperature setpoint of the drying air. It is thus possible to adapt the temperature of the air in the drying zone to the presence or absence of objects to be dried in said drying zone.

In one embodiment, the machine comprises a control unit configured with at least two drying air temperature setpoints: a drying temperature setpoint and a waiting temperature setpoint lower than the drying temperature setpoint. Waiting for objects to dry, the air can be heated to a lower temperature, resulting in a decrease in energy loss and a reduction in energy consumption. The cost of operation of the machine is reduced. Moreover, the cost of washing a dish rack is even lower than the lockers follow one another quickly. In other words, the cost to the rack is all the higher as the flow of the machine is away from the nominal flow. Authorizing a decrease in the temperature of the drying air between two bins allows a significant reduction in the unit cost of a rack in the case of a machine operating at partial load, which often happens, especially at the beginning or at the end of service, or during off-peak periods, for example off-holidays for a tourist establishment or the opposite for a business canteen.

In one embodiment, the means for detecting the presence of objects to be dried is disposed in the rinsing station, the control unit being configured to output the drying temperature setpoint when detecting the presence of objects. to dry.

The means for detecting the presence of objects to be dried can comprise a pivoting pallet between a first waiting position and a second position of presence of objects to be dried, with return to the first position and pivoting from the first to the second position. position when passing objects to dry in contact with the pallet. The means for detecting the presence of objects to be dried also comprises a displacement sensor of the pallet.

The return means of the pallet from the second to the first position may comprise a spring or a ramp for operation under the effect of gravity, or a pivot axis of the pallet slightly inclined relative to the vertical or a counterweight. In operation, the entry of a dish rack in the rinsing station causes contact by the pivoting of the pallet, the detection of the displacement of the pallet by the sensor, the sending by the sensor of a signal to the control unit which then emits a drying temperature setpoint received by the drying air heating means, thereby increasing the temperature of the drying air and which can take place before the entry of the rack of dishes in the drying area. The residence time of the dish rack in the rinsing station may be sufficient to allow a significant rise in the temperature of the drying air. In addition, the pallet can be positioned more or less upstream or downstream in the rinsing station according to the desired duration of temperature rise of the drying air, taking into account the forward speed of the conveyor.

In one embodiment, an upstream part of the washing machine, for example a washing station or a prewash station, comprises an additional washing object detection means disposed in the washing station or in the station. prewash and may be in a form similar to that of the means for detecting the presence of objects to be washed in the rinsing station.

In another embodiment, the triggering of the washing station or the prewash station, in particular the actuation of the pumps, is coupled to the emission of the waiting temperature setpoint, thus allowing a first heating of the pump. drying air from the beginning of the wash. Alternatively, the control unit sends the waiting temperature setpoint when the washing machine is put into operation.

In one embodiment, the drying temperature is between 75 and 90 °, preferably between 78 and 82 °.

In one embodiment, the standby temperature is between 50 and 70 °, preferably between 55 and 65 °. The dishwashing method in a tunnel washing machine comprising a conveyor for moving objects to be washed in the washing tunnel, from a washing zone to a rinsing zone and then to a drying zone, the drying being carried out by circulation of heated air, comprises the detection of the presence of objects to be dried and in response to said detection, the modification of the temperature setpoint. It is thus possible to provide a much lower waiting temperature than the drying temperature, which results in substantial energy savings, for example in the case of a low flow of dish racks. The operation of the drying station at the standby temperature requires a lower energy, of the order of

10% to 40% compared to the operation at the drying temperature.

In addition, the energy losses being reduced, warming of the laundry room in which the washing machine is located is reduced, resulting in better working conditions for the staff.

The temperature of the drying air can be regulated at the first temperature as soon as the machine is started.

The temperature of the drying air can be regulated at the first temperature from the start of organs of the washing or rinsing station, for example a washing or rinsing pump.

In one embodiment, the drying air heating means comprises a heat pump provided with a drying air cooling element, which causes condensation of moisture contained in said drying air with condensation water discharge, and a heating element of the air cooled and dried thereby generating a hot and dry air ensuring quality drying.

The present invention will be better understood on reading the detailed description of some embodiments taken as non-limiting examples and illustrated by the appended drawings, in which:

FIG 1 is a schematic view of a washing machine according to one aspect of the invention;

FIG. 2 is a detail view of FIG. 1; and FIGS. 3 and 4 show variants of FIG. 1. As can be seen in FIG. 1, the washing machine referenced 1 as a whole comprises a washing part 2, a rinsing part 3 and a part of drying 4 defining a tunnel 5. The washing machine 1 also comprises a conveyor 6 extending in the bottom of the tunnel 5 and protruding upstream of the washing part 2 and downstream of the drying part 4. The conveyor 6 is provided to move translational lockers 7 containing dishes 8 to be washed. The conveyor 6 may comprise rails for sliding the bins, a movable advance bar in the direction of the arrow 9, and non-return tabs.

For example, a rack 7 has been shown in the drying part 4. The rack 7 is loaded with dishes 8, including plates, glasses, cutlery, etc. The dish racks 7 are provided to move upstream to downstream of the washing machine in the direction of the arrow 9 according to the movement of the conveyor 6. The washing portions 2 and rinsing 3 comprise water projection, not shown.

The drying part 4 comprises a drying zone 10 within the tunnel 5, a fan 1 1 and a heating element 12 making it possible to create a flow of hot air moving downwards in the direction of the arrows 13 through the zone The fan 11 and the heating element 12 are arranged in the upper part of the drying station 4. The heating element 12 may comprise at least one electrical resistance and / or a combustion heater. The air flow 13, after being passed through the dishes 8, can spread to the rinsing station 3, to the outlet of the washing machine 1 or be recycled and sucked by the fan 1 1. The station drying 4 also comprises a control unit 14 provided for controlling the operation of the fan 1 1 and the heating element 12.

The washing machine 1 comprises a dish rack presence detector 15 situated upstream of the drying station 4, along the conveyor 6, for example in the rinsing station 3. The detector 15, shown in more detail in Figure 2, comprises a pallet 16 pivotally mounted about an axis 17, for example vertical. The pallet 16 can pivot on an angle of the order of a few tens of degrees and is brought into position by a return element 18, for example a spring. The return element may be arranged around the axis 17 or in contact with the pallet 16. The return element 18 tends to keep the pallet 16 in the waiting position projecting in the space traversed by the compartments 7 dishwashing.

The detector 15 further comprises a sensor 19 whose output is connected to the control unit 14. The sensor 19 is configured to detect the movement of the pallet 16. Thus, when a dish rack 7 passes through the detector 15, the edge of the bin 7 comes into contact with the pallet 16 and pushes it out of its path, in opposition to the effect of the return element 18. In the position thus displaced from the pallet 16, the sensor 19 sends a signal to the control unit 14 which then generates a modification of the temperature set point of the drying station 4.

In standby period, that is to say during operation of the washing machine 1 before a dish rack 7 does not trigger the detector 15, the temperature setpoint may be equal to 60 °. In the drying phase, after detection of the passage of a dish rack 7 by the detector 15, the temperature setpoint sent by the control unit 14 to the heating element 12 may be equal to 80 °. The walls of the drying station 4 are therefore already substantially at the standby temperature when the temperature setpoint goes to the drying temperature. This results in a reduction of the energy taken to heat the inside of the tunnel at the drying zone 10 during the transition from the standby temperature to the drying temperature. The forward speed of the conveyor 6 can be known, it is sufficient to have the detector 15 sufficiently upstream of the drying station 4 to allow time for the drying zone 10 to rise to a temperature close to the setpoint of drying temperature. In the embodiment illustrated in FIG. 3, a detector 20 is mounted in the washing station 2 and is connected to the control unit 14. The control unit 14 receives earlier a signal representative of the arrival of a dish rack 7. Thus, if the heating element 12 was inactive, the control unit 14 can send a waiting temperature setpoint, and then when the detector 15 is triggered, a drying temperature setpoint. The detector 20 may be of similar structure to the detector 15.

In an advantageous embodiment, the fan 1 1 is of the type with at least two rotational speeds, a slow speed during the waiting period corresponding to the waiting temperature setpoint and a fast speed after receiving a setpoint. drying temperature. Here again considerably reduces the consumption of energy, in particular electrical energy, during the waiting phases before a drying phase of a rack 7. In fact, during a meal, the flow of pots 7 dishwashing Dirty has a peak for a few tens of minutes preceded and followed by relatively low-flow phases of dirty dish racks. At the beginning and at the end of the service, the control unit 14 allows the hot air of the drying station 4 to go back down from the drying temperature to the waiting temperature between the passage of two bins which follow each other at intervals of time. important.

The embodiment illustrated in FIG. 4 differs from that illustrated in FIG. 1 by three features, which may be provided independently or in combination.

A cooling element 21 is mounted upstream of the heating element 12, for example upstream of the fan 1 1. The cooling element 21 and the heating element 12 form a heat pump assembly, the cooling element 21 comprising an evaporator and the heating element 12 comprising a compressor. The heating element 12 may also include additional electrical resistance. The cooling element 21 generally draws ambient air into the laundry room which can be at a temperature of the order of 20 to 30 ° and is often relatively wet. The cooling element 21 thus causes the condensation of part of the water vapor contained in the sucked-up air, the condensed water being able to flow through a suitable pipe and supplying a dry air to the heating element. 12. Dry air requires less heating energy to reach a given temperature and performs more efficient drying of the dishes 8. The cooling element 21 can also be supplied in whole or in part by air taken. at the bottom of the drying station 4. This avoids sending hot and humid air into the laundry room.

The washing machine 1 further comprises a prewash station 22 arranged upstream of the washing station 2 and ensuring the removal of the coarsest waste from the dishes 8 arranged in a rack 7. The prewash station 22 generally performs a prewash by mechanical action of jets of water at a lower temperature than the washing station 2.

The washing station 2 comprises a control unit 23 connected to at least one pump 24 and at least one valve 25 for controlling the washing of the dishes 8 in the rack 7 during its passage through the washing station 2. control unit 23 of the washing station 2 is connected to the control unit 14 of the drying station 4. The control unit 23 sends to the control unit 14 a piece of information for putting the station into operation. washing 2, at the reception of which the control unit 14 generates the drying temperature setpoint higher than the waiting temperature setpoint. Alternatively, the control unit 14 can be connected to a control unit of the prewash station 22 and / or to a control unit of the rinsing station 3.

In one embodiment, the control unit 14 sends the waiting temperature setpoint as soon as the washing machine 1 is put into general operation, for example by an operator pressing a start button. The control unit 14 sends the drying temperature setpoint on reception of a signal coming from a station arranged upstream, in particular by a dish rack advancement sensor provided for this purpose. After the output of the bin 7 of the drying station 4, the control unit 14 sends a waiting temperature setpoint to the heating element 12. The output of the rack 7 can be determined by a predetermined time elapsed since the sending the drying temperature setpoint.

Alternatively, the output of the rack can be detected by an output detector, for example of the same type as the detector 15, and disposed towards the outlet or downstream of the drying station 4.

In the embodiment of FIG. 4, in the standby phase, the power consumed by the heat pump assembly is reduced.

The possible auxiliary electrical resistance can be cut off. The cooling caused by the evaporator 21 is also relatively low, resulting in less air drying, which is hardly disadvantageous in the absence of dishes to dry but allows substantial energy savings.

Thanks to the invention, the energy consumption of a dishwashing machine is reduced during a partial-regime operation while keeping the dryer ready to function effectively as soon as a dish rack arrives to dry, in particular from a washing station or a rinsing station and while maintaining the flow of the entire washing line.

Claims

1 -Washing machine (1) dishes comprising at least one washing station (2), a rinsing station (3) and a drying station (4) defining a tunnel (5), a conveyor (6) being arranged in the tunnel (5) and able to pass objects at least from the rinsing station (3) to the drying station (4), the drying station (4) comprising means for circulating air to a drying zone (10) for the objects to be dried and a means for heating the circulating air, characterized in that it comprises a means (15) for detecting the presence of objects to be dried, able to modify the set temperature of the drying air.

2-Machine according to claim 1, comprising a control unit (14) configured with at least two drying air temperature setpoints: a drying temperature setpoint and a waiting temperature setpoint lower than the temperature setpoint drying.

3-Machine according to claim 1 or 2, wherein the presence detection means is disposed in the rinsing station (3), a control unit (14) being configured to output the drying temperature setpoint upon detection presence of objects to be dried.

A machine as claimed in any one of the preceding claims, wherein the presence detecting means (15) comprises a pivoting pallet (16) between a first and a second position with return to the first position and pivoting of the first position to the second position during the passage of objects to be dried in contact with the pallet (16), the presence detecting means (1 5) further comprising a sensor (19) for moving said pallet. 5-Machine according to any one of claims 1 to 4, comprising a prewash station (22). 6. Washing machine according to any one of the preceding claims, wherein the set temperature of drying is between 75 and 90 °, preferably between 78 and 82 °.

7-washing machine according to any one of the preceding claims, wherein the set temperature of waiting is between 50 and 70 °, preferably between 55 and 65 °.

8-Method for washing dishes in a tunnel washing machine in which a conveyor (6) passes washing articles in a washing zone, then in a rinsing zone, then in a drying zone (10) with circulation of hot air, the temperature of the drying air being regulated at a first temperature in the absence of objects to be dried and at a second temperature higher than the first temperature in the presence of objects to be dried.

9-Process according to claim 8, wherein the temperature of the drying air is regulated at the first temperature from the start of the machine.

10-Process according to claim 8, wherein the temperature of the drying air is regulated at the first temperature from the start of organs of the washing station or rinsing.