Refrigeration – Automatic control – Refrigeration producer
Reexamination Certificate
2003-04-15
2004-11-23
Norman, Marc (Department: 3744)
Refrigeration
Automatic control
Refrigeration producer
C062S133000, C062S157000, C062S231000, C062S244000
Reexamination Certificate
active
06820436
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application is based upon, claims the benefit of priority of, and incorporates by reference, the contents of Japanese Patent Applications No. 2002-117588 filed Apr. 19, 2002.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicle air-conditioning system of a cold storage type which comprises a cold storage area to be cooled by cold air that passes through a cooling evaporator, and is suitably applied to a vehicle which temporarily stops its vehicle engine, as a compressor driving source, during vehicle stops.
2. Description of the Related Art
For the purposes of protecting the environment and saving fuel, vehicles that stop their engines automatically during vehicle stops, such as at stoplights for example, are called eco-run vehicles. Therefore, “Eco-run” stands for “ECOlogical-run” and “ECOnomy-run.” Eco-run vehicles include hybrid vehicles whose practical, overall use has been increasing.
Normally, the compressor on the refrigeration cycle of a vehicle air-conditioning system is driven by the vehicle engine. With the foregoing eco-run vehicles, each time the vehicle engine is stopped during a vehicle stop, at say, a stoplight, the compressor is also stopped. It follows that the cooling evaporator rises in temperature, and the temperature of the air blown into the passenger compartment increases. This causes a problem in that the cooling of the passengers stops.
There has been a growing need for a vehicle air-conditioning system of a cold storage type which has cold storage for storing coolness (cold heat) when the compressor is in operation, and that can cool the air blown into the passenger compartment by discharging the cold heat stored in the cold storage when the compressor is stopped, that is, when the cooling operation of the cooling evaporator is stopped.
The inventors are currently working on the development of a cold storage type vehicle air-conditioning system mentioned above. When the cold heat stored in the cold storage runs out and the cooling operation stops when the vehicle stops, the outlet air temperature of the cold storage increases. Then, an operation request signal of the vehicle engine is issued to restart the vehicle engine when the outlet air temperature of the cold storage rises to the cooling upper target temperature, such as 18° C., during vehicle stops. Restarting the engine also restarts the compressor, and the cooling evaporator resumes its cooling operation. The loss of air conditioning during vehicle stops can thus be prevented from occurring.
When a stopped vehicle engine is abruptly restarted, when the vehicle is stopped, by the operation request signal from the air-conditioner, passengers may experience an odd or uncomfortable feeling. It is therefore desired that the time over which the cold storage can cool the interior of the compartment by means of discharge of the cold heat stored therein, i.e., the cold discharge cooling remaining time of the cold storage, be calculated and made known to passengers. In this case, it is desired to establish precise agreement between the instant when the indication of the cold discharge cooling remaining time becomes zero and the instant when the vehicle engine is restarted.
In view of this, the inventors have made the following study in order to calculate the cold discharge cooling remaining time of the cold storage for indication to the passengers.
FIG. 7
shows how the outlet air temperature of the cold storage behaves when the vehicle is running and when the vehicle is undergoing an eco-run halt. Here, the eco-run halt refers to the state when the vehicle engine is automatically stopped when the vehicle stops.
In
FIG. 7
, To is the solidifying point, e.g. 8° C., of the cold storage medium contained in the cold storage. When the compressor is driven by the vehicle engine when the vehicle starts running, cold air cooled by the cooling operation of the evaporator passes through the cold storage to cool the cold storage medium. As a result, the outlet air temperature of the cold storage drops toward the solidifying point To of the cold storage medium as seen in the range a.
When the outlet air temperature of the cold storage falls to the solidifying point To, the cold storage medium starts a phase change from a liquid phase to a solid phase (i.e., solidification). The cold heat is thus stored into the cold storage medium in the form of latent heat of solidification. After the start of this solidification, the outlet air temperature of the cold storage is maintained at generally constant temperatures near the solidifying point To of the cold storage medium as seen in the range b. When the cold storage medium completes solidification, it starts to make a sensible heat change. The outlet air temperature of the cold storage drops again toward the outlet air temperature of the evaporator as seen in the range c.
Next, when the vehicle comes to a stop to begin an eco-run halt (i.e., an engine stop), a cold discharge cooling mode is started to cool the interior of the compartment by means of discharge of the cold heat stored in the cold storage. The range d is one in which the cold storage medium makes a sensible heat change. The outlet air temperature of the cold storage thus rises to near the solidifying point To in a short time. Subsequently, the cold storage medium starts a phase change from the solid state to the liquid state (i.e., melting). The cold storage medium thus absorbs latent heat of melting from the air passing through the cold storage.
While the cold storage medium continues melting, the outlet air temperature of the cold storage is maintained at generally constant temperatures near the solidifying point To as shown in the range e. When the cold storage medium completes melting, it starts to make a sensible heat change. The outlet air temperature of the cold storage thus goes up as seen in the range f.
When the outlet air temperature of the cold storage rises to a predetermined cooling upper target temperature TA during the eco-run halt, the operation request signal of the vehicle engine is notified to restart the vehicle engine. Here, the cooling upper target temperature TA is a limit temperature at which passengers start to feel uncomfortable. This temperature, for example 18° C., is determined from sensory evaluations by a plurality of subjects.
Hence, the cold discharge cooling remaining time tx of the cold storage is the time between the current point of eco-run halt and the instant when the outlet air temperature of the cold storage reaches the cooling upper target temperature TA mentioned above. In
FIG. 7
, tx shows the maximum time from the point immediately after the eco-run halt, or rather, the maximum time from the point of eco-run halt until the temperature TA.
It is possible to calculate the cold discharge cooling remaining time tx from changes in the outlet air temperature of the cold storage. Nevertheless, since the outlet air temperature of the cold storage rises at inconsistent rates, the rate of decrease of the remaining time tx is also inconsistent. Thus, the cold discharge cooling remaining time tx cannot be calculated and indicated with accuracy.
To be more specific, the remaining time tx can be calculated by the following equation:
tx
=(
TA−T
now)/&Dgr;
tc,
where Tnow is the cold storage outlet air temperature at present, TA is the cooling upper target temperature, and &Dgr;tc is the amount of change (° C./second) of the cold storage outlet air temperature at present per unit time (1 second).
According to this calculation method, however, the cold discharge cooling remaining time tx cannot be calculated and indicated with accuracy. For example, even if tx is determined to be 30 seconds at time t
1
in
FIG. 8
, the calculation is erroneous due to the presence of the subsequent range e where the outlet air temperature of the cold storage is maintained at generally constant temperatures near the solidifying point To by the latent heat of melting of the cold storage medium
Shirota Yuichi
Tomita Hiroyuki
Denso Corporation
Harness Dickey & Pierce PLC
Norman Marc
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