Patent Description:
A further warewasher having a blower receiving air from two air intake flow paths is known from <CIT>.

Commercial warewashers commonly include a housing area which defines washing and rinsing zones for dishes, pots pans and other wares. In conveyor-type machines wares are moved through multiple different spray zones within the housing for cleaning (e.g., pre-wash, wash, post-wash (aka power rinse) and rinse zones). One or more of the zones includes a tank in which liquid to be recirculated for spraying is heated in order to achieve desired cleaning.

Machines may also include a drying zone at the end of the ware path for drying wares as they exit the machine using a flow of heated air from a blower dryer. Generally, the blower dryer air temperatures T should be above a minimum threshold temperature Tmin and below a maximum threshold Tmax, where at least Tmin is desired to have the right temperature for drying and no more than Tmax is desired to ensure the wares are not too hot for handling and to avoid putting too much heat into the room. Blowing sufficient air over the wares helps both drying and the sheeting action of the final rinse water with or without rinse aid. Maintaining the air at desired conditions for drying can be difficult, given that some wares require different temperature air and/or air flows and/or air moisture levels for proper drying, while at the same time assuring that the wares exiting the machine are not too hot to the touch and/or that the drying air exiting the machine does not add too much heat to the ambient environment.

It would be desirable to provide a warewasher drying system that is adaptable to different conditions.

According to the present invention, a warewash machine for washing wares as defined in claim <NUM> is provided.

In another aspect, a method of operating a blower dryer of a warewash machine involves: selectively and automatically adjusting intake flows to the blower dryer from each of an ambient room air flow path, an internal machine air flow path and a machine exhaust air flow path so as to achieve one or more characteristics of blower dryer output air.

Further features of the present invention are disclosed in the subclaims.

Referring to <FIG>, an exemplary conveyor-type warewash machine, generally designated <NUM>, is shown. Warewash machine <NUM> includes a housing <NUM> that can receive racks <NUM> of soiled wares <NUM> from an input side <NUM>. The wares are moved through tunnel-like chambers from the input side toward a blower dryer unit <NUM> at an opposite exit end <NUM> of the warewash system by a suitable conveyor mechanism <NUM>. Either continuously or intermittently moving conveyor mechanisms or combinations thereof may be used, depending, for example, on the style, model and size of the warewash system <NUM>. Flight-type conveyors in which racks are not used are also possible. In the illustrated example, the racks <NUM> of soiled wares <NUM> enter the warewash system <NUM> through a flexible curtain <NUM> into a pre-wash chamber or zone <NUM> where sprays of liquid from upper and lower pre-wash manifolds <NUM> and <NUM> above and below the racks, respectively, function to flush heavier soil from the wares. The liquid for this purpose comes from a tank <NUM> and is delivered to the manifolds via a pump <NUM> and supply conduit <NUM>. A drain structure <NUM> provides a single location where liquid is pumped from the tank <NUM> using the pump <NUM>. Via the same drain structure, liquid can also be drained from the tank and out of the machine via drain path <NUM>, for example, for a tank cleaning operation.

The racks proceed to a next curtain <NUM> into a main wash chamber or zone <NUM>, where the wares are subject to sprays of cleansing wash liquid (e.g., typically water with detergent) from upper and lower wash manifolds <NUM> and <NUM> with spray nozzles <NUM> and <NUM>, respectively, these sprays being supplied through a supply conduit <NUM> by a pump <NUM>, which draws from a main tank <NUM>. A heater <NUM>, such as an electrical immersion heater provided with suitable thermostatic controls (not shown), maintains the temperature of the cleansing liquid in the tank <NUM> at a suitable level. Not shown, but which may be included, is a device for adding a cleansing detergent to the liquid in tank <NUM>. During normal operation, pumps <NUM> and <NUM> are continuously driven, usually by separate motors, once the warewash system <NUM> is started for a period of time.

The warewash system <NUM> may optionally include a power rinse (also known as post-wash) chamber or zone (not shown) that is substantially identical to main wash chamber <NUM>. In such an instance, racks of wares proceed from the wash chamber <NUM> into the power rinse chamber, within which heated rinse water is sprayed onto the wares from upper and lower manifolds.

The racks <NUM> of wares <NUM> exit the main wash chamber <NUM> through a curtain <NUM> into a final rinse chamber or zone <NUM>. The final rinse chamber <NUM> is provided with upper and lower spray heads <NUM>, <NUM> that are supplied with a flow of fresh hot water via pipe <NUM> running from a hot water booster <NUM> under the control of a solenoid valve <NUM> (or alternatively any other suitable valve capable of automatic control). A rack detector <NUM> may be actuated when a rack <NUM> of wares <NUM> is positioned in the final rinse chamber <NUM> and through suitable electrical controls (e.g., the controller mentioned below), the detector causes actuation of the solenoid valve <NUM> to open and admit the hot rinse water to the spray heads <NUM>, <NUM>. The water then drains from the wares and is directed into the tank <NUM> by gravity flow. The rinsed rack <NUM> of wares <NUM> then exits the final rinse chamber <NUM> through curtain <NUM>, moving into dryer unit <NUM>, before exiting the outlet end <NUM> of the machine.

An exhaust system <NUM> for hot moist air may be provided. A cold water input <NUM> line may run through a waste heat recovery unit (not shown in <FIG>) associated with the exhaust to recover heat from the exhaust air. Other heat recovery components may also be employed. By way of example, the heat recovery system shown in <FIG> may be employed. <FIG> shows a machine using a refrigeration or heat pump system to constantly recover waste heat from exhaust for reuse. As shown, the cold water input <NUM> line may run through a waste heat recovery unit <NUM> (e.g., a fin-and-tube heat exchanger through which the incoming water flows, though other variations are possible) located in the exhaust air flow path to recover heat from the exhaust air flowing across and/or through the unit <NUM>. The water line or flow path <NUM> then runs through one or more condensers <NUM> (e.g., in the form of plate heat exchangers or shell-and-tube heat exchangers, though other variations are possible), before delivering the water to a booster (not shown) for final heating. Additional condensers <NUM> and <NUM> may be provided and could be in heat exchange relationship with other machine fluids (e.g., located in the wash tank of the machine). A second waste heat recovery unit <NUM> may also be provided in the exhaust path. Exhaust blower <NUM> drives air flow across the heat recovery units.

The flow configuration for both incoming fresh cold water and for refrigerant are shown in <FIG>. Cold fresh water delivered via a variable flow control pump <NUM>' (or alternatively by the valve <NUM> of <FIG> ) is first heated by the hot air passing through the waste heat recovery unit <NUM> (e.g., per arrows <NUM>, <NUM>), then heated further by refrigerant when passing through condenser <NUM>. The refrigerant medium circuit <NUM> includes a thermal expansion valve <NUM>, which leads to waste heat recovery unit <NUM> to recover heat from warm waste air (e.g., the exhaust air flow indicated by arrows <NUM>, <NUM>) after some heat has already been removed from the exhaust air flow by unit <NUM>. A compressor <NUM> compresses the refrigerant to produce superheated refrigerant, which then flows sequentially through the condensers <NUM>, <NUM>, and <NUM>.

In practice, when the energy requirement in one or more of the condensers <NUM>, <NUM>, <NUM> is satisfied, the system requires the other condensers to utilize the recovered energy, which is almost constant. In the situation of one or more condensers being energy satisfied during operation, excess heat results in the refrigeration circuit, which in turn results in high blower dryer air temperatures (e.g., because waste heat recovery unit <NUM> does not remove a desired level of heat from the exhaust air stream, which air stream contributes to the blower dryer air flow). In such cases operators may be undesirably exposed to hot blower dryer air and handling of very hot ware at the unloading side of the machine during and after drying.

In addition to excessive heat conditions, as a general rule different wares require different blower air temperatures and flowrates for effective drying. Thus, the blower dryer system described herein can be used in both warewashers including heat recovery systems such as that of <FIG>, and warewashers that do not include heat recovery systems.

Referring to <FIG> and <FIG>, the blower dryer system <NUM> includes an ambient air intake <NUM> from the room and an air intake <NUM> from internal of the machine. Portions of the exhaust air may also be blended in via intake <NUM> in order to make use of the heat in the exhaust air. The air from the machine (e.g.,. from within the tunnel defined by the machine housing) in most cases has higher temperature and humidity compared with the ambient air of the surrounding room. If a constant blower heater system were employed, the lower the blower dryer intake air temperature the lower the blower output air temperature and vice versa. However, the higher the humidity the increased chance of wet wares exiting the machine. Blending of the blower air intakes <NUM>, <NUM> and/or <NUM> can be used to achieve desired objectives for the blower output <NUM> to meet ware dryness and ware temperature (e.g., the blower air temperature, humidity and air flow rate for the ware type and size). Although a variable blower heater could be used to maintain or control the blower air output condition, the inventive blending of the various available intakes leads to energy savings given the various air intake and output conditions desired for different wares.

The blower dryer system <NUM> can blend room air, hot air from within the machine and machine exhaust from the various intakes <NUM>, <NUM> and <NUM> based at least in part upon one or more output characteristics of the blower dryer output air <NUM>. Such characteristics may include blower output air temperature (T), airflow rate (M), humidity (H) and energy (Q) (e.g., as detected by one or more output air sensors <NUM>) and ware dryness or temperature (Tw of ware rack <NUM>). The blower intakes (i.e., room intake air, machine intake air, and machine exhaust) can be controlled manually (e.g., where intake flow control valves <NUM>, <NUM> and <NUM> are manual) or automatically (e.g., where intake flow control valves <NUM>, <NUM> and <NUM> are automated under control of a controller <NUM>) to achieve the right blower output using manual or automatic baffles or valves. The machine exhaust at intake <NUM> may be colder or hotter depending on the type of warewash machine (e.g., with our without energy recovery, respectively). In some cases all the exhaust may be channeled to blower intake depending on the ware type or material, or during startup or machine operation to balance the machine to achieve the right blower air temperature and airflow for the necessary ware dryness.

<FIG> shows individual blower air intakes with respective air flow temperatures T1, T2, T3, humidity or air quality H1, H2, H3 and energy Q1, Q2, Q3 available to be blended in different proportions (e.g., controllable flow rates M1, M2, M3), all of which may be detected by one or more respective intake air sensors <NUM>, <NUM>, <NUM>, to achieve a desired blower output air characteristic of M, T, H and/or Q. Controlling blower output temperature and energy to desired levels could mean lower or higher intake air temperature is required to assure that the blower output temperature T is within and acceptable range of the desired temperature (e.g., as set by minimum and maximum thresholds of Tmin and Tmax, such that Tmin ≤ T ≤ Tmax). Both Tmin and Tmax at a constant blower fan rate are associated with an energy range (e.g., Qmin ≤ Q ≤ Qmax). Qmin pertains to wares that require minimal heat or energy for drying while Qmax pertains to wares that require more heat or energy for drying.

From <FIG> the following relationships between the individual blower intakes and the blower output hold: <MAT> <MAT> <MAT> where Qi = MiTi and <MAT> with i representing the various individual blower intake and "n" the number of intakes.

Equation (<NUM>) provides the relation between the various blower intake airflow Mi and intake airflow temperatures Ti to achieve the right blower output energy Q. This equation assures that the various ratios of the air intake flow maintain Q within an acceptable range of a desired level (e.g., per Qmin and Qmax, where Qmin ≤ Q ≤ Qmax). Generally, it is desired that the air intake <NUM> from the machine area in <FIG> be used, when possible, in the minimum needed to conserve energy in the machine.

To maintain the blower dryer output air energy Q, either the blower output air M increases with low T to maintain Q, which means more of the colder air intake needs to be used, or M is decreased with high T to maintain Q, which means less of the hot air intake needs to be used.

However, there are special cases where Q may need to be below Qmin (Q < Qmin) for drying thermally liable or sensitive wares and/or materials or Q may need to be above Qmax (Q max) for drying some ware types, sizes and/or materials; in these cases either both M and T could be increased or M increased at constant T or T increased at constant M. In most cases, the heating source <NUM> for the blower dryer is operated at a constant level. The various relations involving temperature T, airflow M, humidity or air quality H, energy Q, etc. and combinations such as heat index in addition to Equation (<NUM>), (<NUM>) and (<NUM>) are applicable.

In an exemplary automatic drying system, all the individual intake blower air conditions (temperature Ti, airflow Mi, humidity Hi) as well as the blower output conditions temperature T, airflow M, humidity H may be sensed for decision making. Qi corresponds to the energy of the various intake air sources and Q corresponds to the blower output air calculated using Equation (<NUM>). The ware will be sensed (e.g., type and size) and the size used to regulate the blower output conditions such as temperature T, airflow M, humidity H to meet the need including, dryness of the ware; light ware vs heavy wares which require less or more blower output air, respectively; thermally liable ware or heavy wares which require less or more heat, respectively; situations where the blower has to be in a range to satisfy Qmin < Q < Qmax or outside the range to meet the requirement of Q < Qmin and Q > Qmax. The ware size and/or type, and the detected blower output temperature T, airflow M, humidity H, can be used to control the individual intakes <NUM>, <NUM>, <NUM> to keep the outputs within specified ranges or levels. This means that various intake combinations may be used.

Components <NUM>, <NUM><NUM> (e.g., in the form automatic valves as suggested above, or controllable baffles or other flow control structure) are used to control the individual intake air flowrates, e.g., as controlled by a controller <NUM> that is also connected to sensors <NUM>, <NUM>, <NUM> and <NUM>. As used herein, the term controller is intended to broadly encompass any circuit (e.g., solid state, application specific integrated circuit (ASIC), an electronic circuit, a combinational logic circuit, a field programmable gate array (FPGA)), processor (e.g., shared, dedicated, or group - including hardware or software that executes code) or other component, or a combination of some or all of the above, that carries out the control functions of the machine or the control functions of any component thereof.

In an alternative embodiment, manual controlling or adjusting of the baffles/ valves to achieve the blower output requirement given the type of ware, balancing machine, etc. may be implemented. In this case, components <NUM>, <NUM>, <NUM> represent manual valves or baffles used to control the individual airflow rates.

Claim 1:
A warewash machine (<NUM>) for washing wares (<NUM>), comprising:
- a chamber for receiving wares (<NUM>), the chamber having at least one wash zone with an associated spray system (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) for spraying liquid onto wares (<NUM>) passing therethrough, wherein a downstream drying zone includes a blower (<NUM>) for blowing air onto wares (<NUM>) passing threrethrough,
wherein the blower (<NUM>) includes multiple air intake flow paths for air from respective sources,
wherein the blower includes an ambient air intake (<NUM>) operatively connected
to an ambient air flow path, a machine intake (<NUM>) operatively connected to an internal machine air flow path,
the blower (<NUM>) further includes an exhaust intake (<NUM>) operatively connected to receive air from a hot air machine exhaust flow path;
characterized in that
each of the ambient air flow path, the internal machine air flow path and the machine exhaust air flow path includes a respective adjustable flow control device (<NUM>, <NUM>, <NUM>) for varying an amount of air traveling therealong.