GB2190180A

GB2190180A - Refrigeration apparatus

Info

Publication number: GB2190180A
Application number: GB08709261A
Authority: GB
Inventors: Kazumi Aoki; Minoru Fujiu
Original assignee: Sanden Corp
Current assignee: Sanden Corp
Priority date: 1986-04-19
Filing date: 1987-04-16
Publication date: 1987-11-11
Also published as: JPS62169883U; GB8709261D0; KR870017096U; KR920000708Y1; JPH0537336Y2

Abstract

Refrigeration apparatus for use in a vending machine, which is provided with a plurality of merchandise storage chambers, has a plurality of evaporators (14a, 14b, 14c) which are disposed in the storage chambers, respectively, and coupled with one another in parallel. an electromagnetic valve (15a, 15b, 15c) is coupled in series with each evaporator to control the flow of refrigerant. A single decompression device (13) is disposed on the suction side of the evaporators, and an accumulator (16) is disposed on the discharge side of the evaporators. Therefore, the total amount of circulated refrigerant is fixed without influence from any change in the operating condition of the apparatus. <IMAGE>

Description

SPECIFICATION Refrigeration apparatus for a vending machine This invention relates to refrigeration apparatus for refrigerating a plurality of stored chambers in a vending machine.

Recently, to meet the requirements of customers' tastes, vending machines need to store and dispense various types of merchandise, which should be stored at various temperatures. Therefore, as shown in Fig. 1 of the accompanying drawings, a vending machine 1 is provided with a plurality of chambers 1a, 1b, ic for storing the different types of merchandise and each of which is separated from the others to enable the respective chamber temperatures to be controlled. A heater element 2 and an evaporator 3 of the refrigerating apparatus are disposed in each of the chambers la, 1b and 1c for heating or cooling the chambers, and a blower fan 4 for causing forced air circulation within each of the chambers 1a, 1b and 1c.

The evaporators 3a, 3b and 3c form part of a refrigeration circuit which comprises a compressor 5 and a condenser 6, and are connected with one another in parallel. Each of the evaporators 3a, 3b and 3c is coupled in series with an electromagnetic valve 7, to control the flow of refrigerant, and with a capillary tube 8, which functions as an expansion valve, as shown in Fig. 2. The compressor 5 and condenser 6 are disposed in a chamber id formed below the storage chambers, and ventilated by a blower fan 9.

The heating and cooling of each of the storage chambers is controlled by changing the operation of the heater and evaporator, and the maintainance of a temperature is controlled by the operation of the heater or by the flow of refrigerant passing through the evaporators.

In the above mentioned refrigeration circuit, if the all evaporators are operated, the total amount of circulated refrigerant will be identified by "i"., and refrigerant inflow resistance at capillary tube is identified "R1", the amount of refrigerant inflow into each evaporator will be "i/3". Under the above explained condition, i.e., the condensing pressure and evaporating pressure are held uniformly, if one of the electromagnetic valves, for example the first valve 7a, is closed (as shown in Fig. 3) the refrigerant passageway is closed to maintain the temperature of the storage chamber la, i.e., the temperature of the first storage chamber la has reached its predetermined temperature. The total amount of refrigerant flow is then reduced to "2i/3" and refrigerant inflow into each of the evaporators 3b and 3c is maintained at "i/3".However, the condensation capacity of the condenser 6 is predetermined, that is the capacity of the condenser 6 is not able to vary in accordance with variation in the flow of refrigerant. As the amount of refrigerant inflow is reduced, the effective capacity of the condenser 6 is increased in accordance with the amount of refrigerant inflow. Therefore, the condensing pressure and evaporating pressure are reduced, and furthermore, liquid refrigerant accumulates within the evaporator. In accordance with the reduction of condensing pressure and condensing temperature, the evaporating pressure and evaporating temperature of the evaporator 6 are also reduced.Furthermore, the inflow resistance "R1" of the capillary tube is increased, since the pressure difference between the condensing pressure and evaporating pressure is relatively reduced as compared with the situation of operating all three evaporators. Thus, the total amount of circulated refrigerant is smaller than the expected amount "i/3", thereby causing a failure of refrigerating capacity. Also, under the above mentioned condition, the compressor is continuously rotated to refrigerate the chambers.

Furthermore, as shown in Fig. 3b, if two of the three evporatores 3a, 3c cease to operate owing to closure of their electromagnetic valves 7a, 7c, the total amount of circulated refrigerant is identified by "i/3" under the same condition referred to the Fig. 2. But, as explained with reference to Fig. 3a, the condensing pressure and evaporating pressure are further reduced due to reduction of the total amount of circulated refrigerant. Therefore, the evaporating pressure reaches a vacuum condition and the compressor is operated under a vacuum condition. Thus, the compressor could be damaged, and also the refrigerating operation to cool down the chamber becomes worse.

It is a primary object of this invention to provide a refrigerating apparatus for a vending machine which can stabilize the refrigerating capacity.

It is another object of this invention to provide a refrigerating apparatus which maintains the condensing and evaporating pressures under variable operating conditions.

In accordance with the invention, in refrigeration apparatus, for refrigerating a plurality of merchandise storage chambers in a vending machine, and comprising, coupled in series to form a closed refrigerant circuit, a compressor, a condenser and a plurality of evaporators which are arranged, in use, to be disposed in different merchandise storage chambers in the vending machine, the evaporators are coupled in series with respective electromagnetic valves and in parallel with one another, and a common decompression device is disposed on the suction side of the evaporators.

Preferably a common accumulator is disposed on the discharge side of the evaporators to accumulate excess liquid refrigerant.

In the accompanying drawings: Figure 1 is a diagrammatic sectional view of a vending machine containing refrigeration apparatus; Figure 2 is a view illustrating the corre sponding conventional refrigeration circuit; Figures 3a and 3b are diagramatic circuits illustrating operating modes of the Fig. 2 cir cuit under different conditions; Figure 4 is a view illustrating a refrigeration circuit in accordance with one embodiment of this invention; and, Figures 5a and 5b are diagrammatic circuits illustrating operating modes of the Fig. 4 circuit under different conditions.

Referring to Fig. 4, a refrigeration apparatus for use in a vending machine comprises a compressor 11, a condenser 12, a decom pression device, such as a capillary tube 13, a plurality of evaporators 14 and electromagnetic valves 15, and an accumulator 16.

These basic components are coupled in series to form a conventional refrigerant circuit. Each evaporator 14a, 14b, 14c and its electromagnetic valve 15a, 15b, 15c are coupled in series and the serially connected evaporators and electromagnetic valves are connected in parallel with one another. The evaporators 14a, 14b, 14c are disposed in isolated storage chambers formed in the vending machine, to refrigerate the respective chambers.

In the above mentioned construction of the refrigeration circuit, the refrigerant is compressed in the compressor 11 and supplied to the condenser 12 where it is condensed to liquid refrigerant. The liquid refrigerant is delivered to the capillary tube 13. The refrigerant expands as it flows through the tube 13 and emerges as a two-part mixture of liquid gas and gas, but primarily liquid. As the refrigerant mixture flows through an evaporator 14, which acts as a heat exchange in conjunction with a blower (not shown), which supplies air to the interior of the isolated stored chamber, heat is transferred from incoming air to the refrigerant and the entire refigerant vaporizes to a gaseous state. The refrigerant gas at the evaporator outlet is then passed to the suction side of the compressor through the accumulator 16.

When all three evaporators 14a, 14b and 1 4c are operated, that is refrigerant flows into the three evaporators 14a, 14b and 14c, the amount of inflow refrigerant in each evaporator is identified by "i/3", under condition that the inflow resistance of the capillary tube 13 is "R2", and the total amount of circulated refrigerant is "i". If the one of three evaporators, for example the first evaporator 14a, ceases to operate, i.e., flow of refrigerant into the first evaporator 1 4a is prevented by operation of its electromagnetic valve 15a, the total amount of circulated refrigerant is determined by "i", since the inflow resistance in the capillary tube 13 is fixed. Also, the amount of refrigerant flow into each operated evaporator 14b, 14c is "i/2", as shown in Fig. 5a.Because, the condensating pressure and evaporating pressure are maintained at a predetermined level which is determined under the operating condition that three evaporators are operated, the total amount of circulated refrigerant is not reduced. Furthermore, under the above condition, such that two evaporators are operated, the amount of inflow refrigerant into each evaporator is increased, thereby increasing the refrigerating capacity of each evaporator 14b, 14c. Thus, effective operation of the refrigerating apparatus can be achieved.

Furthermore, even if only one evaporator, for example the second evaporator 14b is operated, as shown in Fig. 5b, the total amount of circulated refrigerant ''i'' is not changed, because the inflow resistance at the capillary tube 13 is not changed and is maintained as "R2". Therefore, the condensating pressure and evaporating pressure are maintained at a normal level, and only the amount of inflow refrigerant into the second evaporator 1 4b is changed. Thus, the refrigerating capacity of the second evaporator 1 4b is furthermore increased to achieve an effective operation of the refrigeration apparatus.

On the other hand, the capacity of each evaporator 14a, 14b and 14c is primarily determined by consideration of the configuration of the storage chambers of the vending machine and manufacturing cost. Therefore, when the number of operating evaporators is limited, i.e., as shown in Fig. 5b where only one evaporator 14b is operated, the amount of inflow refrigerant into the second evaporator 1 4b might exceed the predetermined amount for the evaporator. In this case, liquid refrigerant might be sucked into the compressor 11 and caused several problems, for example damage to the discharge valve ect.

The accumulator 16 is thus disposed just before the suction port of compressor 11 to accumulate excess liquid refrigerant and change it to gaseous refrigerant.

As mentioned above, the amount of inflow refrigerant into a plurlity of evaporators, each of which respectively refrigerates a chamber of a vending machine to independently maintain the temperature in each merchandise storage chamber, could be controlled by a decompression device in accordance with variation in the number of operating evaporators.

Therefore the operating condition of refrigerating apparatus, such as the evaporating pressure and condensing pressure, may be fixed, even if the number of operating evaporators is changed. Thus, refrigerating efficiency of the apparatus is stabilized.

Claims

1. Refrigeration apparatus, for refrigerating a plurality of merchandise storage chambers in a vending machine, and comprising, coupled in series to form a closed refrigerant circuit, a compressor, a condenser and a plurality of evaporators which are arranged, in used, to be disposed in different merchandise storage chambers in the vending machine, wherein the evaporators are coupled in series with respective electromagnetic valves and in parallel with one another, and a common decompression device is disposed on the suction side of the evaporators.

2. Apparatus according to claim 1, wherein a common accumulator is disposed on the discharge side of the evaporators.

3. Refrigeration apparatus for a vending machine, substantially as described with reference to Figs. 1, 4 and 5 of the accompanying drawings.

4. A vending machine having a plurality of merchandise storage chambers and refrigeration apparatus according to any one of the preceding claims with the evaporators positioned in different ones of the chambers.