Freezer/refrigerator vehicle

Details Freezer/refrigerator vehicle Freezer/refrigerator vehicle

1999-10-12

2001-03-06

Tanner, Harry B. (Department: 3744)

Refrigeration

Automatic control

Preventing, removing or handling atmospheric condensate

C062S323100, C062S323300, C123S339170

Reexamination Certificate

active

06196009

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a freezer/refrigerator vehicle for transporting foods and the like in a frozen state or in a cold storage state. More particularly, the invention relates to a freezer/refrigerator vehicle equipped with a refrigerating apparatus driven by a drive source which is an engine for running the vehicle, that is mounted on a vehicle.
DESCRIPTION OF THE PRIOR ART
In recent years, freezer/refrigerator vehicles have been widely used for transporting foods and the like in a frozen state or in a cold storage state. As a drive source for driving the compressor of the refrigerating apparatus in the freezer/refrigerator vehicles, there are two types of a system in which a special engine exclusively used for the refrigerating apparatus is mounted and a system which utilizes the output of the engine for running the vehicle, that is mounted on the vehicle. In the vehicles of the former system, a special engine must be mounted and hence, invites an increase in the cost and weight and needs a space for mounting it. Therefore, the system that utilizes the output of the engine for running the vehicle has been generally employed.
The system which utilizes the output of the engine, mounted on the vehicle, for running the vehicle includes a system in which the compressor of the refrigerating apparatus is driven directly by the engine for running the vehicle via a clutch and a system in which an AC generator is driven by the engine for running the vehicle and the compressor of the refrigerating apparatus is driven by an AC motor driven by the output of the AC generator. The cooling performance of the refrigerating apparatus varies in proportion to the rotational speed of the compressor. in the system in which the compressor of the refrigerating apparatus is directly driven by the engine for running the vehicle, it has a problem that the engine rotational speed is low during the low-speed traveling of the vehicle or during the idling, and consequently, the cooling performance of the refrigerating apparatus decreases. Owing to its simple structure and simple control operation, however, this system has been widely practically used. On the other hand, in the system in which the compressor of the refrigerating apparatus is driven by the output of an AC motor that is driven by the engine for running the vehicle, the frequency of the AC electric power supplied to the AC motor is controlled by an inverter, making it possible to increase the rotational speed of the compressor irrespective of the rotational speed of the engine. Therefore, this system has now been generally used, and it is disclosed in, for example, Japanese Examined Patent Publication (Kokoku) No. 103137/1994.
In the system in which the compressor of the refrigerating apparatus is driven by utilizing the output of the engine for running the vehicle, there is a problem that the driving force of the engine during the idling (550 rpm in the case of, for example, a diesel engine) is so small that the engine causes hunting due to the load of the refrigerating apparatus. Accordingly, in the freezer/refrigerator vehicle equipped with a refrigerating apparatus driven, as a driving source, by the engine for running the vehicle, an idle-up means is provided for increasing the amount of feeding fuel in order to increase the engine rotational speed to, for example, about 800 rpm during the idling of the engine. Under the idle-up condition, the engine rotational speed is considerably higher than that under the no-load condition, with the consequence that engine noise becomes considerably great. Further, the engine for driving the compressor of the refrigerating apparatus must bear a large load when the external temperature is high, and must bear an extremely large load of the refrigerating apparatus particularly when the freezer/refrigerator vehicle gets directly a lot of the sunlight and the temperature on the outer wall of the refrigerating apparatus elevates up to about 70° C. To prevent occurrence of the hunting in the engine due to the load of the refrigerating apparatus, the idle-up means works to increase the amount of feeding fuel. Meanwhile, at night where no sunlight falls and the temperature of the external air is low, the load of the refrigerating apparatus decreases and the rotational speed of the engine needs not be so much increased. In the conventional freezer/refrigerator vehicle, however, the idle-up means solely increases the amount of feeding fuel even when the load of the refrigerating apparatus is small, like in the case where the load is large. Therefore, during the traffic jam in which the idling lasts long and, particularly, during the traffic jam at night, the engine noise during the idling arouses a problem.
Further, the freezer/refrigerator vehicle for delivering foods and the like in a frozen state or in a cold storage stage to the stores, must keep the refrigerating apparatus operated even when the vehicle parks at the store for unloading the cargoes and hence, the engine is operated under the idle-up condition. With the engine being operated under the idle-up condition (e.g., 800 rpm) for extended periods of time during the parking of the vehicle at the store, however, the engine noise could become a cause of noise pollution.
In order to solve the above-mentioned problems, the present applicants have proposed in Japanese Patent Applications Nos. 288310/1998 and 288311/1998 a freezer/refrigerator vehicle in which the idle-up means is constructed to work to operate the fuel feeding device under the first idle-up condition or under the second idle-up condition between the first idle-up condition and the no-load condition when the refrigerating apparatus is in operation during the idling of the engine, and the idle-up means is operated under the first idle-up condition when the load of the refrigerating apparatus is high or when the vehicle is not in a parking state, and is operated under the second idle-up condition when the load of the refrigerating apparatus is low or when the vehicle is in a parking state.
The refrigerating apparatus has a refrigerating cycle for circulating the coolant compressed by the compressor through a condenser and an evaporator, and a defrosting cycle for introducing the coolant compressed by the compressor into an evaporator without passing the condenser. When the refrigerating apparatus has worked in a state of the refrigerating cycle for a predetermined period of time (e.g., 3 hours), then, the defrosting cycle is executed for a predetermined period of time (e.g., 30 minutes) to remove frost adhered onto the evaporator. However, when, while the engine is in operation under the above-mentioned second idle-up condition, the defrosting cycle is executed and then the refrigerating cycle is resumed, the coolant compressed by the compressor just after the resumption has high temperature. Due to this, an overload is exerted on the compressor, whereby the rotational speed of the engine drops and it makes difficult to maintain the predetermined performance. In particular, when the AC motor for driving the compressor is controlled by the frequency, the AC motor can be no longer rotated.
SUMMARY OF THE INVENTION
The main object of the present invention is to provide a freezer/refrigerator vehicle that, even when the defrosting cycle is executed while the engine is in operation under a low idle-up condition, can smoothly conduct the subsequent refrigerating cycle.
In order to solve the above-mentioned main technical problem according to the present invention, there is provided a freezer/refrigerator vehicle equipped with a refrigerating apparatus which has a refrigerating cycle for circulating the coolant compressed by a compressor through a condenser and an evaporator and a defrosting cycle for introducing the coolant compressed by the compressor into the evaporator without passing the condenser, said refrigerating apparatus being driven by a drive source that is an engine for running the vehicle, mounted on a vehicle, comprising
an idle-up means for operat

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