JPH04211894A - Cooling device for automatic vending machine - Google Patents

Abstract

PURPOSE:To realize the operation in the optimum cooling cycle to plural mer chandise rooms with easy adjustment and low cost. CONSTITUTION:A main tube path where a main solenoid valve and a main capillarly tube are serially connected and a sub tube path where a sub solenoid valve and a sub capillarly tube are serially connected are parallely connected, and an evaporator part where the evaporator is serially connected to this parallel tube path is provided for each merchandise room to be cooled. The main solenoid valve operating according to the temperature for each merchandise room and the sub solenoid valve operating according to the overheating of each evaporator are respectively turned on and off by the control part.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a cooling device that uses a compressor to repeatedly liquefy and evaporate a refrigerant to obtain a low temperature. This invention relates to a cooling device for vending machines that can be realized with.

0002

2. Description of the Related Art A conventional example will be explained with reference to FIG. FIG. 3(a) is a side view of the conventional example, and FIG. 6(b) is a plan view of the evaporation chamber. In this conventional example, the temperature of four product compartments in which products to be cooled are stored is controlled with each cooling set value as a target, and the cooling is performed using a refrigeration cycle method using a compressor. Figure 3(a),(b)
In this case, each set of product chambers 5A and 5B has a common evaporation chamber 5.
C constitutes one space, and each wall 5a is between these three rooms.
, 5b, 5c so as to be able to communicate with each other. A slider 54 is provided to open and close the hole in the wall 5c. The same applies to each product room 6A, 6B. That is, it is constituted by each member designated by reference numeral 6 instead of 5. The configuration of the cooling device includes a common compressor 41 and a condenser 42,
A solenoid valve 51 corresponds to each evaporation chamber 5C, 6C.
, a capillary tube 52, and an evaporator 53; and a solenoid valve 61, a capillary tube 62, and an evaporator 63. Each evaporation chamber 5C, 6C
The evaporators 53 and 63 are respectively installed in the evaporators 53 and 63.

Temperature control is performed by a thermostat 57 and a thermostat 67. thermostat 57
, thermostat 67 is provided at the inlet of each evaporator 53, 63 installed in each evaporation chamber 5C, 6C. Control regarding the room temperature of each product room 5A, 5B, 6A, and 6B is as follows. This will be explained using product room 5A as a representative. If the room temperature is above the set value, the solenoid valve 51 is opened. As a result, the refrigerant flows and the evaporator 53 cools the evaporation chamber 5C. wall 5a
The room temperature of the product compartment 5A is lowered by the circulation of cold air in the space including the evaporation chamber 5C and the product compartment 5A through the gaps on both sides of the product compartment. As the room temperature of the product room 5A decreases, the evaporator 53
When the evaporation temperature of the thermostat 57 also decreases and becomes below the low temperature setting of the thermostat 57, the contacts of the thermostat 57 are opened and the solenoid valve 51 is closed. Thereafter, when the evaporation temperature of the evaporator 53 rises and becomes equal to or higher than the high temperature setting of the thermostat 57, the solenoid valve 51 is opened again. By repeating this operation, the evaporation temperature is kept constant. As a result, the temperature of the product compartment 5A is kept constant near the evaporation temperature. Note that at this time, the hole in the wall 5c is closed by the slider 54. The same applies to the product room 5B. In FIG. 3(b), the cold air is circulated by the blower 55 in the direction shown by short arrows and directional symbols, such that it rises in the lower part of the figure and descends in the upper part. In addition, each product room 5A, 5
If the room temperature of room B is to be cooled at the same time, the manual operation type is used, in which the hole in the wall 5c is opened with the slider 54, and the cold air that has passed through the evaporator 53 is sent by the blower 56, as shown by the long arrow and directional symbol in FIG. 3(b). This is also possible by providing directions.

0004

[Problems to be Solved by the Invention] In the conventional example as explained above, for example, when the room temperature of each product compartment 5A, 5B simultaneously exceeds a set value, the temperature of each product compartment 5A, 5B is
Since cooling cannot be performed in parallel, the rapid response of cooling is poor. As a countermeasure, it is possible to install an evaporator in each product compartment 5A and 5B, but since a capillary tube is used as an expansion valve, the operating range is narrow, and it is difficult to distribute the optimal amount of refrigerant to many evaporators. The problem is that it is difficult. Also,
There is a method used in multi-air conditioners to install an evaporator in each product room. That is, an electronic expansion valve, such as a linear expansion valve driven by a pulse motor, is used as the expansion valve, and the degree of superheating of the evaporator, that is, the temperature difference between saturated steam and superheated steam, or in other words, the temperature difference between the evaporator outlet and inlet. The opening degree of the electronic expansion valve is controlled to keep it constant. However, in the case of vending machines, the cooling capacity is smaller than in the case of multi-air conditioners, and therefore the amount of refrigerant is small, so it is very difficult to manufacture electronic expansion valves, and at the same time there are problems such as increased costs. Another countermeasure is to use an on-off valve instead of a linear expansion valve and control the pulse width so that the degree of superheating of the evaporator is constant. This method has the problem that the frequency for controlling the on-off valve must be selected to be a sufficiently small value compared to the system time constant for optimal control, which shortens the life of the on-off valve. be.

An object of the present invention is to provide a cooling device for a vending machine that solves the problems of the conventional technology and realizes operation in an optimal cooling cycle for multiple product compartments with easy adjustment and low cost. It is about providing.

[0006]

[Means for Solving the Problem] In order to solve this problem, a cooling device for a vending machine according to claim 1 is a cooling device that obtains a low temperature by repeatedly liquefying and evaporating a refrigerant using a compressor. , a main conduit in which a main solenoid valve and a main capillary are connected in series, and a sub conduit in which a sub solenoid valve and a sub capillary are connected in series are connected in parallel, and the parallel connected conduit is connected to the evaporation. Evaporator units in which evaporators are connected in series are connected in parallel, with the limit being the number of product compartments that store products to be cooled, and one or more of the evaporators are installed in one or more of the product compartments. is installed, and the corresponding main solenoid valve is turned on and off according to the temperature of each product compartment,
A control unit is provided that turns on and off the corresponding sub-electromagnetic valve according to the degree of superheating of each of the evaporators. In the cooling device for a vending machine according to a second aspect of the invention, in the device according to the first aspect, the product compartment and the evaporation chamber correspond to each other on a one-to-one basis. The cooling device for a vending machine according to claim 3 is the device according to claim 1 or 2, wherein the on/off operation of the main solenoid valve is such that the temperature of the corresponding product compartment rises or falls around a set value. Based on this, the on/off operation of the auxiliary solenoid valve is based on the fact that the degree of superheat of the corresponding evaporator goes down or up with the set value as the boundary. A cooling device for a vending machine according to claim 4 is the device according to any one of claims 1 to 3, in which one of the return pipes including a solenoid valve is provided in the series pipe between the compressor and the condenser. Alternatively, two or more solenoid valves are connected in parallel, and each of the solenoid valves is turned on and off depending on the operating state of each main solenoid valve and sub solenoid valve.

[0007]

[Operation] In the cooling device for a vending machine according to claim 1, the control unit causes the main solenoid valve and the sub solenoid valve to match the temperature of the product compartment and the degree of superheat of the evaporator to corresponding set values, respectively. It works on and off. That is, since cooling control is performed in two stages based on the product room temperature, which is the "result," and the degree of superheating of the evaporator, which is the "cause," optimal refrigeration cycle operation is possible. It is also possible that the product compartments and the evaporators do not all have a one-to-one correspondence, and for example, one evaporator is partially shared by two product compartments. In the cooling device for a vending machine according to the second aspect, since the product compartment and the evaporator correspond to each other on a one-to-one basis, cooling is performed for each product compartment. In the cooling device for a vending machine according to claim 3, the main solenoid valve is turned on and off based on the temperature of the corresponding product compartment rising and falling with a set value as a boundary, and the sub solenoid valve is turned on and off based on the temperature of the corresponding product compartment rising and falling with a set value as a boundary. - The off operation is performed based on whether the degree of superheat of the corresponding evaporator goes below or above the set value, respectively. In the cooling device for a vending machine according to claim 4, each solenoid valve of the return pipe connected in parallel to the series pipe of the compressor and the condenser is controlled according to the operating state of each main solenoid valve and the sub solenoid valve. ,
That is, when the sum of the refrigerant flow rates flowing through the steam pipes is large, the return flow rate is reduced, and when the sum is small, the return flow rate is increased.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a cooling device for a vending machine according to the present invention will be described with reference to FIG. 1, which is a block diagram, and FIG. 2, which is a time chart of various signals showing operations. In FIG. 1, 1 is a compressor, 2 is a condenser, and the areas indicated by horizontal lines with arrows are evaporator sections 10, 20, and 30, which consist of an evaporator, a solenoid valve, and a capillary tube, as will be described in detail later. This is the main part of the invention. A compressor 1 and a condenser 2 are connected in parallel to each other, such as a series-connected conduit between the solenoid valve 3 and the capillary tube 5, and a series-connected conduit between the solenoid valve 4 and the capillary tube 6.
and are provided in parallel with each other to form a return conduit. A control circuit 8 controls the operation of the entire refrigeration cycle.

[0009]Each evaporator section 10, 20, 30 is installed corresponding to each product compartment (not shown). The evaporator section 10 will be explained as a representative example. The evaporator section 10 has a main pipe line in which a main electromagnetic valve 11 and a main capillary tube 13 are connected in series;
A sub-duct line in which the sub-electromagnetic valve 12 and the sub-capillary tube 14 are connected in series is connected in parallel, and the evaporator 1 is connected to this parallel-connected pipe line.
5 are connected in series. The evaporator 15 is installed in the product room,
Cool the product compartment. The main solenoid valve 11 operates the flow rate of the refrigerant based on the temperature of the product compartment, and the sub solenoid valve 12 operates the flow rate of the refrigerant based on the degree of superheating of the evaporator 16. Of course, the control circuit 8 is involved in this operation. By manipulating these two refrigerant flow rates, the cooling operation is performed comprehensively and rationally.

The temperature of the product compartment corresponding to the evaporator section 10 is measured by a temperature sensor 18, and the degree of superheating of the evaporator 15 is measured by an internal temperature sensor 16 and an outlet temperature sensor 17. As already mentioned, the temperature sensor 16
The temperature of the saturated steam is measured by the temperature sensor 17, and the temperature of the superheated steam is measured by the temperature sensor 17, and the difference in temperature is the degree of superheat.

The flow coefficient of the main electromagnetic valve 11 and the main capillary 13 is actually represented by the flow coefficient of the main capillary 13, which is 0.36. The main capillary tube 13 has an inner diameter of 1
．． 1mm, length 2m, auxiliary solenoid valve 12, auxiliary capillary tube 1
The flow coefficient of the pipe No. 4 is 0.18. Here, the flow coefficient of a conduit or capillary is a measure of its ease of flow or ability to allow fluid to flow through it, and is expressed as a flow rate at a unit differential pressure. The flow coefficient of this parallel conduit or parallel capillary tube is variable in the range of 0.18 to 0.54. In other words, by varying the flow rate within this range, evaporator 1
This means that the cooling capacity of No. 5 can be changed by three times. By the way, each evaporator section is not limited to one-to-one correspondence to each product compartment, and for example, one evaporator unit can be shared by two product compartments.

The operation of this embodiment will be explained with reference to the time chart of various signals shown in FIG. In the same figure, Dm, Dn: each state signal of the main solenoid valve and the sub solenoid valve (
(on/off state), Θ: product room temperature, Θs: set temperature of room temperature, Δ: degree of superheat of the evaporator, Δs: set value of the degree of superheat. Note that the product room temperature, main solenoid valve, etc. correspond to a certain representative product room.

Initially, Θ and Δ are the corresponding Θs and Δ, respectively.
Since it is in a state exceeding or less than Δs, Dm,D
All n are in the ON state. That is, the refrigerant flows through the evaporator section at the maximum flow rate, increasing the cooling capacity of the evaporator. As a result, Δ increases and when it reaches Δs, Dn is turned off. After a further delay in time, when Θ decreases and reaches Θs, Dm is turned off. Note that the reason why the decrease in Θ is slower than the decrease in Δ is that Δ is the cause and Θ is the result.

Further, Dm is turned on and off in small increments as Θ rises and falls within a narrow range near Θs, that is, ON-OFF control is performed with the set temperature as Θs. Similarly, Dn is turned ON and OFF in small increments as Δ goes up and down in a narrow range near Δs, that is, the set heating degree is changed to Δ
ON-OFF control is performed as s. Note that the rate of increase in Δ is slightly slower when only Dn is ON than when both Dm and Dn are ON. This is not expressed in Figure 2.

Finally, the function of the return line in FIG. 1 will be explained. The function of this return line is that each evaporator section 1
In other words, the apparent flow rate of refrigerant supplied from the compressor 1 and condenser 2 is adjusted to an appropriate value according to the refrigerant flow rates related to 0, 20, and 30. It is to do so. Therefore, when refrigerant does not flow through any of the evaporation pipes, the compressor 1 and condenser 2 do not operate, so the function of the return pipe is unnecessary, and the solenoid valves 3 and 4 are turned off, that is, closed. state. When the refrigerant flows through only one of the evaporation pipes, it is necessary to increase the return flow rate, so both electromagnetic valves 3 and 4 are turned on, that is, in an open state. Furthermore, when the refrigerant flows through two of the evaporation pipes, the return flow rate needs to be somewhat small, so only one of the electromagnetic valves 3 and 4, for example, only the electromagnetic valve 3, is turned on. When refrigerant flows through all three evaporation pipes, no return flow rate is required.
Both solenoid valves 3 and 4 are turned off.

[0016]

In the device according to claim 1, the control unit turns on and off the main solenoid valve and the sub solenoid valve so that the temperature of the product compartment and the degree of superheat of the evaporator match the corresponding set values, respectively. Operate. Therefore, ■ It is possible to operate the optimal refrigeration cycle for multiple product compartments, and ■ Since it does not use special parts and has a simple configuration, it is very easy to adjust the operation of the optimal refrigeration cycle. , ■Since the structure and operation are simple, operation in the optimal refrigeration cycle can be achieved with high reliability and at low cost. In particular, in the apparatus according to the second aspect, since the product compartment and the evaporator part correspond to each other one-to-one, temperature control can be performed satisfactorily. In particular, in the device according to claim 3, the on/off operation of the main solenoid valve is based on the fact that the temperature of the corresponding product compartment increases or decreases with a set value as a boundary, and the on/off operation of the sub solenoid valve is based on , on the basis that the degree of superheating of the corresponding evaporator goes below and above the set value as a boundary. Therefore, since the control algorithm is simple, the reliability of the control operation can be improved. In particular, in the device according to claim 4, each solenoid valve of the return line connected in parallel to the series line of the compressor and condenser is each main solenoid valve,
Depending on the operating state of the auxiliary solenoid valve, that is, when the sum of the refrigerant flow rates flowing through the steam pipes is large, the return flow rate is reduced, and when the sum is small, the return flow rate is increased. Works off. Therefore, even if the total flow rate of refrigerant may fluctuate depending on the temperature condition of each product compartment, the optimal amount of refrigerant is distributed to the evaporator corresponding to each product compartment without causing load fluctuations on the compressor. can do.

[Brief explanation of the drawing]

[Fig. 1] Configuration diagram of an embodiment according to the present invention

[Figure 2] Time chart of various signals in this embodiment

[Fig. 3] Regarding the conventional example, (a) is a side view thereof, (b)
is a plan view of the evaporation chamber

[Explanation of symbols]

1 Compressor 2 Condenser 3,4 Solenoid valve 5,6 Capillary tube 8 Control circuit 10, 20, 30 Evaporator section 11, 21, 31 Main solenoid valve 12, 22, 32 Sub solenoid valve 13, 23, 33 Main capillary 14, 24, 34 Secondary capillary 15, 25, 35 Evaporator

Claims (4)

[Claims] Claim 1: A cooling device that uses a compressor to repeatedly liquefy and evaporate a refrigerant to obtain a low temperature, comprising: a main conduit in which a main electromagnetic valve and a main capillary are connected in series, and a sub-electromagnetic valve and a sub-capillary. The evaporator section, in which the series-connected sub-main pipes are connected in parallel, and the evaporator for evaporation is connected in series to the parallel-connected pipes, limits the number of product compartments that store the products to be cooled. The evaporators are installed in one or more of the product compartments, and the corresponding main solenoid valves are turned on and off according to the temperature of each product compartment. A cooling device for a vending machine, comprising a control section that turns on and off the corresponding sub-electromagnetic valve according to the degree of superheat of each of the evaporators. 2. The cooling device for a vending machine according to claim 1, wherein the product compartment and the evaporator correspond to each other on a one-to-one basis. 3. The device according to claim 1 or 2,
The on/off operation of the main solenoid valve is based on the temperature in the corresponding product compartment rising or falling around the set value, and the on/off operation of the sub solenoid valve is based on the degree of superheating of the corresponding evaporator. A cooling device for a vending machine characterized by having a configuration based on lowering and raising a set value as a boundary. 4. The apparatus according to claim 1, wherein one or more return pipes including a solenoid valve are connected in parallel to the series pipe between the compressor and the condenser; 2. A cooling device for a vending machine, wherein each of the solenoid valves is configured to turn on and off depending on the operating state of each main solenoid valve and sub solenoid valve.