DE102008041265A1 - Condensation dryer for drying laundry, has controller provided with evaluation unit that evaluates difference between conductance and marginal conductance in view of presence of unallowable operating condition - Google Patents

Abstract

The dryer (1) has a blower (19) arranged in a processing air circuit (2), and a conductance sensor (21) arranged in a drying chamber (3) for measuring a conductance of articles to be dried. A controller (10) exhibits a comparison unit (22) for comparison of the conductance measured after specific period from beginning of the drying process with a marginal conductance stored in the controller. The controller has an evaluation unit (23) that evaluates a difference between the conductance and the marginal conductance in a view of a presence of an unallowable operating condition.

Description

The invention relates to a condensation dryer with a drying chamber for the objects to be dried, a process air circuit in which a blower is arranged, a heat pump in which a refrigerant circulates and which has an evaporator, a compressor, a condenser and a throttle, one in the Drying chamber arranged conductance sensor for measuring a conductance L _{C of} the objects to be dried and a controller.

Such a condensation dryer is apparent from the DE 40 23 000 C2 ,

In A condensation dryer is air (so-called process air) through a blower over a heater in a damp Laundry containing drum as a drying chamber directed. The hot air takes moisture out of the drying laundry items on. After passage through the drum, the then moist process air in a heat exchanger passed, which is usually preceded by a lint filter. In this heat exchanger (eg air-air heat exchanger or heat sink of a heat pump) becomes the humid Cooled process air, so that in the humid process air contained water condenses. The condensed water is subsequently generally collected in a suitable container and the cooled and dried air again the heater (which may be the heat source of a heat pump can be) and then fed to the drum.

This Drying process may be very energy intensive, because of the cooling of the process air in the heat exchanger heated cooling air flow energetically the process can get lost. By using a heat pump leaves this energy loss can be significantly reduced. In one with a Heat pump equipped condensation dryer takes place the cooling of the warm, moisture-laden process air essentially in a heat sink of the heat pump, where the heat withdrawn from the process air, for example, for evaporation a refrigerant used in the heat pump is used. The heat absorbed in the heat sink becomes the heat source within the heat pump transported and there again - if necessary opposite the temperature at the heat sink elevated temperature - again issued. in a heat pump with a refrigerant as a heat transport medium, the refrigerant evaporated in the heat sink and in the heat source liquefied, passes the vaporized, gaseous Refrigerant via a compressor to the heat source, which can be referred to here as a liquefier, where due the condensation of the gaseous refrigerant Heat is released, which is used to heat the process air is used before entering the drum. The liquefied refrigerant finally flows back through a throttle to the evaporator; the throttle serves to reduce the internal pressure in the refrigerant, so that this in the evaporator with renewed Recording of heat can evaporate. The heat pump, operated in such a way with a circulating refrigerant is also known as the "compressor heat pump". Other types of heat pump are also known.

The DE 40 23 000 C2 discloses a clothes dryer with a compressor heat pump, in which a supply air opening is arranged in the process air channel between the condenser and the evaporator, which is closable with a controllable closure device.

Of the traditionally used air-air heat exchangers - in Cross operation or operated in countercurrent operation - and The electric heaters are generally complete by one Heat pump replaced. This can be compared to a Dryers with air-to-air heat exchanger and resistance heating a reduction of the energy requirement for a drying process from 20 to 50% can be achieved.

A Compressor heat pump usually works optimally in certain temperature ranges in the evaporator and condenser. Problematic when using a compressor heat pump in the condensation dryer is the usually high temperature in the condenser, which can lead to the fact that the Refrigerant is no longer or no longer complete can be liquefied; then the compressor has to be switched off be and / or a significantly deteriorated effect of the heat pump be accepted. This problem is even bigger if the compressor by an additional heating in the process air circuit is supported, to a faster heating of the process air and thus achieve shorter drying times. Moreover, can it is due to contamination of the airways to a disability the circulating process air come. This can also become one Increase the temperature of the refrigerant lead. Such operating conditions can lead to injury heat pump or other parts of the dryer and are therefore inadmissible.

In a conventional dryer, an impermissible operating state, for example a reduced circulation of the process air (air power reduction), is determined by detecting a temperature in the process air stream above a heater for the process air and in front of the drying chamber at regular intervals and in each case from two consecutively detected values a difference value is formed, which is a temporal gradient corresponds. This information generally need not be available in this form for a dryer equipped with a heat pump (heat pump dryer). For example, in a heat pump dryer, the heat pump is often farther from the drying chamber than the heater in a conventional condensation dryer. In any case, the detection of an impermissible operating state in a condensation dryer, which is equipped with a heat pump, in this way only inaccurately possible.

task The invention therefore was the provision of a condensation dryer with a heat pump, in which easily present an impermissible operating state can be detected.

The Solution of this problem is achieved according to this invention by a condensation dryer with the features of the corresponding independent patent claim. Preferred embodiments the condensation dryer according to the invention are in corresponding dependent claims listed.

The invention thus relates to a condensation dryer with a drying chamber for the objects to be dried, a process air circuit in which a fan is arranged, a heat pump in which a refrigerant circulates and which has an evaporator, a compressor, a liquefier and a throttle, a in the drying chamber arranged Leitwertsensor for measuring a conductance L _{C of} the objects to be dried and a controller, characterized in that the controller first means for comparing the measured after a period .DELTA.t ₁ after a start of a drying process conductance L _C with a stored in the controller first limit conductance L _C ^lim1 and second means for the evaluation of a difference ΔL ₁ between the conductance L _C and L _C ^lim1 in view of the presence of an impermissible operating state.

Of the used herein is "conductivity sensor" interpreted broadly and includes not only the determination of a conductance, but also a corresponding measured value such as a voltage when applying a specific current value between two electrodes of the sensor. Given that in a rotating drum Trained drying chamber the drying well in constant Movement is held, it is also assumed that the conductivity sensor no quasi-constant or only slowly changing measured values supplies. In such a case, one is about at least one complete rotation of the drying chamber determined maximum of the conductance or, if the measurement as a measurement of an electrical Resistance is carried over, at least over a complete rotation of the drying chamber determined To accept the minimum of the resistance as the actual measured value.

Also the term used herein is "illegal Operating condition "to be interpreted broadly. This is every operating condition meant to interfere with a drying process and / or cause damage to the condensation dryer can. However, a certain focus is on detection such improper operating conditions that the Heat pump, and on the protection of the heat pump before operating conditions, for their function and their stock could be problematic.

The Invention has the advantage that the operation of the condensation dryer can be monitored in a simple and effective way. Impermissible operating conditions can be sure be displayed so that appropriate countermeasures taken can be. The heat pump and in particular their condensers can be in an optimal temperature range work. This allows the operation of the condensation dryer with a particularly favorable energy balance. Furthermore the heat pump is spared.

The Among other things, the invention is based on the fact that the progression of a Drying process by comparison with suitable specifications, here of the at least one limit conductance, is monitored. If the effect of a drying process, measured by the reduction the conductivity of the material to be dried, it becomes so bad that a predetermined Grenzleitwert is exceeded, then represents a simple and reliable, in particular according to the invention device installed by software in the controller finds that an inadmissible operating condition exists, and gives appropriate Information to a user of the dryer.

Preferably, the first means of the condensation dryer according to the invention is designed such that the evaluation of the difference .DELTA.L ₁ in regard to the presence of an impermissible operating state is to determine whether L _C is greater than L _C ^lim1, wherein an impermissible operating state is detected if L _{C is} greater than L _C ^lim1 . Accordingly, the determination of an impermissible operating state is based on the fact that the drying of the moist material takes place too slowly in comparison to a model process, from which the specification of the limiting conductance derives.

In a preferred embodiment of the condensation dryer, the first means is additionally for a comparison of the conductance L _C after a period .DELTA.t ₂ after the beginning of a drying process ses ^configured with a stored in the control second ^{Grenzleitwert} L _C ^lim2 , where .DELTA.t _{2 is} greater than .DELTA.t ₁ . In this case, L _C ^lim2 is preferably L _C ^lim1 . In any case, therefore, two measurements take place at successive times, whereby a particularly high level of security and accuracy of the determination of the presence of an impermissible operating state is possible.

Further preferred is an embodiment in which the first means is designed such that the evaluation of the difference ΔL ₂ between the conductance L _C and L _C ^lim2 in view of the presence of an inadmissible operating state consists in determining whether L _{C is} greater than L _C ^lim2 , wherein an invalid operating condition is detected when L _{C is} greater than L _C ^lim2 . Accordingly, also based the time after the period .DELTA.t _2, the detection of an impermissible operating state that the drying of the damp product in comparison to a process model, in which the specification of the Grenzleitwertes derives occurs too slowly.

Preferably, the controller is arranged to display a first warning when an invalid operating condition is detected after the time Δt ₁ and to display a second warning and to cancel a running drying process when an invalid operating condition is detected at the time Δt ₂ . Thus, the first time an improper operating condition is detected, the drying process continues, indicating a corresponding warning, and then, when the next time the determination is made again and the presence of an improper operating condition is manifested, not only to warn again, but to interrupt the drying process.

Moreover, the condensation ^{dryer according} to the invention preferably has third means for determining the conductance L _C ^lim1 in dependence on a quantity and / or type of objects to be dried. These third means may consist in a device for determining the mass of the filled laundry items. In the case of a large amount of filled laundry items, the decrease in the conductance L _C in the period Δt ₁ or else in the period Δt ₂ will generally be smaller than with a smaller amount of filled laundry items. Moreover, in general, the degree of moisture of the filled laundry will be important; this can also be determined, if necessary, by measurements of the conductance L _C at an early stage of the drying process.

The first limit ^value L _C ^lim1 and possibly also the second limit ^value L _C ^lim2 can thus be suitably estimated and the estimated values stored in the controller of the condensation dryer.

The first limit conductance L _C ^lim1 and the second limit conductance L _C ^{lim2 are preferably set} in consideration of a conductance value L _C ⁰ determined at the beginning of the period Δt ₁ and stored in the controller for the purposes of the invention. In a preferred embodiment, the course of the conductance L _C as a function of time during the period .DELTA.t ₁ or in the period .DELTA.t ₂ in this case can be followed, taking into account the conductance L _C ⁰ and / or the first Grenzleitwerts L _C ^lim1 and / or the second ^{Limit value} L _C ^lim2 determined and evaluated in terms of an impermissible operating state of the condensation dryer.

Of the Condenser dryer according to the invention preferably has an acoustic and / or visual display means for displaying a inadmissible operating state. An optical display means may be a liquid crystal display on which certain Prompts or instructions are given. It can additionally or alternatively light-emitting diodes in one or more colors come on. The type of display of an impermissible operating state can depends on the type of impermissible operating state be.

at a generally less critical first impermissible one Operating state could, for example, on a liquid crystal display a request to clean the airways in the condenser dryer, be specified. Alternatively or in addition to this could a light-emitting diode, for example in yellow-red color, light up.

at a second impermissible operating state, which in the Usually critical, for example, could be on a liquid crystal display an indication that the drying process has been interrupted and the Heat pump should be checked, if necessary with the involvement of a service technician. alternative or in addition to this could be a light emitting diode, for example, in a deep red color, light up.

The Advertisement could also have an audible indication take place, with different impermissible operating conditions could be indicated by different beeps.

The Heating of the process air can exclusively via take place the condenser of the heat pump. It Can also use an electric heater become.

If, in addition to the heat pump, a further heater is used in the condensation dryer according to the invention, this is preferably one Two-stage heating. The control of this heater is also used in a preferred embodiment of the invention for controlling the temperature of the refrigerant.

There as the degree of drying progresses in the condenser dryer to be dried objects the necessary energy for the drying decreases, it is convenient to the heat pump and if necessary to regulate an additional heating accordingly, d. H. with increasing degree of drying their heating power too reduce the balance between the supplied and to maintain the necessary drying energy.

With increasing degree of drying of the objects to be dried, especially laundry, thus a lower heat output or even an increasing cooling capacity of the heat pump required. In particular, after a completed Drying phase, the temperature in the process air circuit increase sharply. In general, therefore, the heat pump is regulated so that in the drying chamber a maximum allowable temperature is not exceeded.

For monitoring the temperature of refrigerant or heat pump and possibly the temperature of the process air are generally the person skilled in per se known temperature sensor in the heat pump and / or used in the process air circuit.

The Refrigerant used in the heat pump is preferred selected from the group, the propane, carbon dioxide the known fluorinated hydrocarbons R134a and R152a and the fluorinated under the names R407C and R410A Hydrocarbons exists.

The Temperature of the refrigerant of the heat pump, in particular in the liquefier, is inventively in Generally about the control of the heat pump kept within the permissible range. When the inventive Condensation dryer in the process air circuit before entering the Drying chamber is located an additional heater preferably the control of the heat pump in coordination performed with the control of heating.

Prefers is an improved controllability of the temperature of the refrigerant in the heat pump, in particular in the condenser, by the combination of a heat pump with a cooling device, in particular an additional heat exchanger and / or a given additional blower.

Further details of the invention will become apparent from the following description of non-limiting embodiments of the condensation dryer according to the invention and a method using this condensation dryer. Reference is made to the 1 to 4 ,

1 shows a vertical section through a condensation dryer according to a first embodiment.

2 shows a schematic representation of the process air circuit and the heat pump for in 1 shown first embodiment.

3 shows a vertical section through a condensation dryer according to a second embodiment, in which an additional heater and an additional air-to-air heat exchanger are used.

4 shows a schematic representation of the process air circuit and the heat pump for in 3 shown second embodiment.

1 shows a vertically cut condensation dryer (hereinafter abbreviated to "dryer") according to a first embodiment, in which the heating of the process air takes place exclusively via the condenser of the heat pump.

The in 1 illustrated dryer 1 has a drum rotatable about a horizontal axis 3 as a drying chamber 3 on, within which carriers 4 are attached to the movement of laundry during a drum rotation. Process air is achieved by means of a blower 19 through a drum 3 as well as a heat pump 13 . 14 . 15 . 17 in an air duct 2 guided in a closed circuit (process air circuit 2 ). After passing through the drum 3 The moist, warm process air is cooled down and reheated after condensation of the moisture contained in the process air. This is heated air from the back, that of a door 5 opposite side of the drum 3 through whose perforated bottom into the drum 3 passed, comes there with the laundry to be dried in contact and flows through the filling opening of the drum 3 to a lint filter 6 within a door closing the filling opening 5 , Subsequently, the air flow in the door 5 deflected downwards and in the air duct 2 to the evaporator 13 a heat pump 13 . 14 . 15 . 17 led, where it is cooled. This in the evaporator 13 Vaporized refrigerant of the heat pump is supplied via a compressor 14 to the liquefier 15 directed. The resulting in the evaporator condensate is collected in a condensate container not shown here, from where it can be disposed of by emptying or pumping. In the liquefier 15 the refrigerant liquefies with heat being released to the process air. The present in liquid form refrigerant is then to a additional heat exchanger 16 led, which is together with a second blower 20 in a cooling air duct 12 located, and from there via a throttle 17 , which may be formed as a valve, aperture or capillary, in turn to the evaporator 13 , whereby the refrigerant circuit is closed. The cooling air is taken from the room air and returned to the room air after heat exchange.

The drum 3 will be in the in 1 shown embodiment on the rear floor by means of a pivot bearing and front by means of a bearing plate 7 stored, with the drum 3 with a brim on a sliding strip 8th on the bearing plate 7 rests and is held at the front end. The condensation dryer is controlled by a controller 10 by the user via a control unit 9 can be regulated.

The control 10 comprises first means as an additional or integrated component 22 to compare the conductance L _C after a period .DELTA.t ₁ from the beginning of a drying process with one in the controller 10 stored first limiting conductance L _C ^lim1 , and second means 23 for the evaluation of a difference ΔL ₁ between the conductance L _C after the period Δt ₁ and L _C ^lim1 in view of the presence of an impermissible operating state.

At the in 1 shown embodiment is in the drying chamber 3 a conductivity sensor 21 arranged as well as a third remedy 26 for determining the conductance L _C ^lim1 depending on the amount and / or type of laundry to be dried. An optical display means 24 serves to indicate an impermissible operating state, whereby different colors can indicate different impermissible operating states.

The first means 22 is designed such that the evaluation of the difference ΔL ₁ in view of the presence of an impermissible operating state in the determination of whether L _{C is} greater than L _C ^lim1 , wherein an invalid operating condition is determined when L _{C is} greater than L _C ^lim1 , Accordingly, the determination of an impermissible operating state is based on the fact that the drying of the objects to be dried takes place too slowly in comparison to a model process, from which the specification of the limiting conductance derives.

The first means 22 is additionally designed for a comparison of the conductance L _C after a period .DELTA.t ₂ after the beginning of a drying process with a stored in the control second ^{Grenzleitwert} L _C ^lim2 , wherein .DELTA.t _{2 is} greater than .DELTA.t ₁ . Where L _C ^lim2 is L _C ^lim1 . Thus, two measurements are taken at successive times, whereby a particularly high level of safety and accuracy of the determination of the presence of an impermissible operating state is possible.

Besides, this is the first remedy 22 such that the evaluation of the difference ΔL ₂ between the conductance L _C and L _C ^lim2 in view of the presence of an inadmissible operating state consists in the determination as to whether L _{C is} greater than L _C ^lim2 , wherein an inadmissible operating state is determined, if L _{C is} greater than L _C ^lim2 . Accordingly, also based the time after the period .DELTA.t _2, the detection of an impermissible operating state that the drying process as compared to a model, from which the specification of the Grenzleitwertes derives occurs too slowly.

The control 10 is set up to display a first warning on the display 24 if after the time .DELTA.t ₁ an illegal operating condition is detected, and to display a second warning and to cancel a running drying process, if at the time .DELTA.t ₂ an impermissible operating state is detected. Thus, the first time an improper operating condition is detected, the drying process continues, indicating a corresponding warning, and then, when the next time the determination is made again and the presence of an improper operating condition is manifested, not only to warn again, but to interrupt the drying process.

2 shows a schematic representation of the process air circuit 2 and the heat pump 13 . 14 . 15 . 17 for the in 1 shown first embodiment. While the process air in the closed process air circuit 2 and the refrigerant in closed loop in the heat pump 13 . 14 . 15 . 17 are guided, the means of the second blower 20 for cooling the refrigerant of the heat pump 13 . 14 . 15 . 17 in the additional heat exchanger 16 used air taken from the room air and after passing through the additional heat exchanger 16 returned to the room air.

3 shows a vertically cut condensation dryer (hereinafter abbreviated to "dryer") according to a second embodiment, in which an additional heat exchanger is located both in the heat pump and in the cooling air duct of an air-to-air heat exchanger.

The in 3 illustrated dryer 1 has a drum rotatable about a horizontal axis as a drying chamber 3 on, within which carriers 4 are attached to the movement of laundry during a drum rotation. Process air is achieved by means of a blower 19 via an electric heater also present in this embodiment 18 through a drum 3 , an air-to-air heat exchanger 11 . 12 as well as a heat pump 13 . 14 . 15 . 17 in an air duct 2 guided in a closed circuit (process air circuit 2 ). After passing through the drum 3 The moist, warm process air is cooled down and reheated after condensation of the moisture contained in the process air. It is from the heater 18 heated air through the perforated bottom of the drum 3 from the one door 5 opposite side into the drum 3 directed. There, the heated air comes into contact with the laundry to be dried and flows through the filling opening of the drum 3 to a lint filter 6 within a door closing the filling opening 5 , Subsequently, the air flow in the door 5 deflected downwards and from the air duct 2 to the air-to-air heat exchanger 11 . 12 directed. There condenses due to cooling the moisture absorbed by the process air from the laundry items at least partially and is in an in 3 dashed drawn condensate tank 21 collected from which it can be disposed of. Subsequently, the slightly cooled process air to the evaporator 13 the heat pump 13 . 14 . 15 . 17 led, where it is further cooled. This in the evaporator 13 vaporized refrigerant of the heat pump is via the compressor 14 to the liquefier 15 directed. That in the evaporator 13 accumulating condensate is collected in a condensate container not shown here, from where it can be disposed of by emptying or pumping. In the liquefier 15 the refrigerant liquefies with heat being released to the process air. The refrigerant, which is now in liquid form, subsequently becomes an additional heat exchanger 16 led, located in the cooling air duct 12 the air-to-air heat exchanger 11 . 12 between this and a second blower 20 located, and from there via a throttle 17 turn to the evaporator 13 , whereby the refrigerant circuit is closed. The cooling air is taken from the room air and after passing through the air-to-air heat exchanger 11 . 12 returned to the room air.

The drum 3 will be in the in 3 shown embodiment on the rear floor by means of a pivot bearing and front by means of a bearing plate 7 stored, with the drum 3 with a brim on a sliding strip 8th on the bearing plate 7 rests and is held at the front end. The condensation dryer is controlled by a controller 10 by the user via a control unit 9 can be regulated as already for 1 described.

The control 10 also includes first funds 22 to compare the conductance L _C after a period .DELTA.t ₁ with one in the controller 10 stored first limit conductance L _C ^lim1 and second means 23 for the evaluation of a difference ΔL ₁ between the conductance L _C after the period Δt ₁ and L _C ^lim1 in view of the presence of an impermissible operating state.

At the in 3 shown embodiment is in the drying chamber 3 also a conductivity sensor 21 arranged as well as a third remedy 26 for determining the conductance L _C ^lim1 depending on the amount and / or type of laundry to be dried. An optical display means 24 serves to indicate an impermissible operating state, whereby different colors can indicate different impermissible operating states.

4 shows a schematic representation of the process air circuit and the heat pump for in 3 shown second embodiment. While the process air in the closed process air circuit 2 and the refrigerant in the closed loop of the heat pump 13 . 14 . 15 . 17 is guided, which is used for cooling in the air-to-air heat exchanger 11 . 12 used air taken from the room air, over the second blower 20 after passing through the additional heat exchanger 16 to the air-to-air heat exchanger 11 . 12 passed and then fed back into the room air.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• - DE 4023000 C2 [0002, 0005]

Claims (8)

Condensation dryer ( 1 ) with a drying chamber ( 3 ) for the objects to be dried, a process air circuit ( 2 ), in which a blower ( 19 ), a heat pump, ( 13 . 14 . 15 . 17 ), in which a refrigerant circulates and the one evaporator ( 13 ), a compressor ( 14 ), a liquefier ( 15 ) and a throttle ( 17 ), one in the drying chamber ( 3 ) arranged conductivity sensor ( 21 ) for measuring a conductance L _{C of} the objects to be dried and a controller ( 10 ), characterized in that the controller ( 10 ) first means ( 22 ) for comparing the conductance L _C measured after a period of time Δt ₁ after a start of a drying process with one in the controller ( 10 ) stored first boundary conductance L _C ^lim1 and second means ( 23 ) for the evaluation of a difference ΔL ₁ between the conductance L _C and L _C ^lim1 in view of the presence of an impermissible operating state. Condensation dryer ( 1 ) according to claim 1, characterized in that the first means ( 22 ) Is designed such that the evaluation of the difference .DELTA.L ₁ in regard to the presence of an impermissible operating state is to determine whether L _C is greater than L _C ^lim1, wherein an impermissible operating state is detected if L _C is greater than L _C ^lim1 is. Condensation dryer ( 1 ) according to one of the preceding claims, characterized in that the first means ( 22 ) additionally for a comparison of the conductance L _C after a period Δt ₂ after a start of a drying process measured conductance L _C with a in the control ( 10 ) is ^configured second limit conductance L _C ^lim2 , wherein .DELTA.t _{2 is} greater than .DELTA.t ₁ . Condensation dryer ( 1 ) according to claim 3, characterized in that L _C ^lim2 is L _C ^lim1 . Condensation dryer ( 1 ) according to one of claims 3 and 4, characterized in that the first means ( 22 ) is designed such that the evaluation of the difference ΔL ₂ between the conductance L _C and L _C ^lim2 in view of the presence of an impermissible operating state in the determination of whether L _{C is} greater than L _C ^lim2 , wherein an inadmissible operating state is detected if L _{C is} greater than L _C ^lim2 . Condensation dryer ( 1 ) according to one of claims 3 to 5, in which the controller ( 10 ) is arranged to display a first warning when after the time .DELTA.t ₁ an illegal operating condition is detected, and to display a second warning and to cancel a running drying process when at the time .DELTA.t ₂ an illegal operating condition is detected. Condensation dryer ( 1 ) according to one of the preceding claims, characterized in that the controller ( 10 ) third means ( 26 ) for determining the conductance L _C ^lim1 depending on the amount and / or type of objects to be dried in each case at the beginning of a drying process. Condensation dryer ( 1 ) according to one of the preceding claims, characterized in that the controller ( 10 ) an acoustic and / or visual display means ( 24 ) for indicating an inadmissible operating state.