1. Field of the Invention
The present invention relates to an ice making machine for making ice by means of a cooling function of an evaporator in a refrigeration circuit and accomplishing de-icing through a rise in temperature of the evaporator.
2. Description of the Prior Art
As one example of a conventional kind of ice making machine, the machine disclosed in Japanese Patent Laid-Open No. 2000-213841 is known. As shown in
The operation of this conventional example is as follows. At the time of ice making, as known in the art, ice is formed by a refrigerating action imparted to latent heat (i.e., an endothermic action). The refrigerating action is generated when liquid refrigerant is vaporized inside the evaporator 6.
In contrast, at the time of de-icing, when the valve 9A of the gas line 9 is opened, low-temperature refrigerant gas inside the receiver 3 is introduced into the evaporator 6. The evaporator 6 is heated to conduct de-icing by latent heat produced when this gas condenses (i.e., an exothermic action). At the same time, because the pressure on the high pressure side decreases, the CPR 8 operates so that hot gas from the compressor 1 is supplied to the receiver 3 through the bypass line 1A to promote vaporization of the liquid refrigerant inside the receiver 3, whereby more refrigerant gas is introduced into the evaporator 6 to continue the de-icing.
The fundamental function of the CPR 8 in the refrigeration cycle described above is as follows. For example, in a case such as in wintertime when the outdoor air temperature is low and the cooling capacity of the condenser 2 has become excessively high, when the pressure on the high pressure side of the compressor 1 drops to a predetermined value the CPR 8 is activated to allow hot gas from the compressor 1 to flow to the side of the receiver 3, to thereby accumulate liquid refrigerant in the condenser 2 and reduce the cooling capacity. Naturally, in a case such as in summertime when the outdoor air temperature is high, the CPR 8 exerts the maximum cooling capacity by, conversely, closing the channel on the side of the bypass line 1A to allow high-temperature, high-pressure refrigerant from the compressor 1 to flow into the condenser 2.
However, when this refrigeration cycle is assessed with respect to its de-icing function, the following problem emerges. That is, when the outside air temperature is not remarkably high, there is no problem with the de-icing performance because hot gas from the compressor 1 is supplied to the receiver 3 through the bypass line 1A by the above-described action of the CPR 8. However, when the outside air temperature is high, the hot gas from the compressor 1 is fed to the receiver 3 after being cooled in the condenser 2, thus causing a decrease in the de-icing performance.
According to this invention, there is provided an ice making machine that includes a bypass line and a valve device that enable hot gas from the compressor to be supplied to the evaporator by bypassing the condenser. Therefore the hot gas is not cooled in the condenser, even when the outside air temperature is high. Thus, efficient and stable de-icing operations can be performed regardless of the operating conditions such as the outside air temperature.
Hereunder, embodiments of the present invention are described based on the attached drawings.
Embodiment 1 of this invention is described hereafter referring to
On the side of the external unit 19, a three-way valve 25 that has two inlets and that corresponds to a first valve device is connected to the outlet side of the aforementioned CPR 23. One of the inlets of the three-way valve 25 is connected to the outlet of the condensing pressure regulating valve 23. The other inlet is connected to the first bypass line 21 through a branch line 21A. The outlet of the valve 25 is connected via the line 18A to the receiver 13 that is disposed on the internal unit 20 side.
In the internal unit 20, a second bypass line 27 branches from the refrigerant supply line 18A at a position near the inlet side of the receiver 13 to connect to the inlet side of the evaporator 16. An open/close valve 28 that corresponds to a second valve device is provided partway along the second bypass line 27.
As described later, the three-way valve 25 and the open/close valve 28 are subject to switching control or open/close control by a valve controller 50 in accordance with the timing of an ice making operation and a de-icing operation.
Next, the operation of Embodiment 1 will be described.
As shown in
When a sensor or the like detects that a predetermined ice making time has lapsed or that a predetermined quantity of ice has been made, the operation switches to a de-icing operation.
Upon entering the de-icing operation, the condenser fan 12A is stopped, the three-way valve 25 switches to the side of the first bypass line 21, and the open/close valve 28 opens. Thereupon, as shown by the arrow with a dashed line in
When the hot gas is introduced into the evaporator 16, the evaporator 16 is heated by manifest heat because the temperature of the hot gas is sufficiently high in comparison to the ice. When the internal pressure of the evaporator 16 rises to produce a condensation temperature of 0C or more, heating is performed by manifest heat plus the latent heat produced by the condensation, thus efficiently carrying out the de-icing. When the de-icing operation finishes, the operation switches again to an ice making operation, and the condenser fan 12A, the three-way valve 25, and the open/close valve 28, switch to their respective opposite states to resume ice making.
As described above, even though the interval between the external unit 19 and the internal unit 20 in Embodiment 1 is of a structure that has piping that comprises 2 pipes (i.e., the refrigerant supply line 18A and the refrigerant return line 18B), because the structure allows hot gas from the compressor 11 to be introduced directly into the evaporator 16 upon entering a de-icing operation, both the manifest heat of the hot gas and the latent heat produced when the hot gas is condensed can be utilized to heat the evaporator 16. Further, since the introduction of the hot gas can be performed in a similar manner regardless of a rise or fall in the ambient temperature of the condenser 12, an efficient and stable de-icing action can be carried out regardless of the operating conditions, such as the outside air temperature for example.
In Embodiment 2, when switching to a de-icing operation, a time difference is implemented between switching of the three-way valve 25 to the side of the first bypass line 21 and opening of the open/close valve 28. More specifically, as shown by the dashed line in the above-described
In this embodiment, the above Embodiment 2 is further developed. While there is a general tendency to consider it disadvantageous for a de-icing operation to introduce the liquid refrigerant remaining in the refrigerant supply line 18A into the evaporator 16 when commencing a de-icing operation, it has been confirmed that, on the contrary, when the temperature of that liquid refrigerant is high the de-icing performance is enhanced. This is thought to be due to the superior heat transfer properties of liquid as compared to those of gas. Alternatively however, when the temperature of the liquid refrigerant is low the liquid refrigerant results in a weakening of the effect of the hot gas.
Therefore, a temperature sensor (not shown in the figure) is provided that detects the ambient temperature of the external unit 19 to thereby detect the temperature of the liquid refrigerant remaining inside the refrigerant supply line 18A through condensation. Thus, as shown in
When the temperature of liquid refrigerant remaining in the refrigerant supply line 18A is high, the liquid refrigerant is introduced into the evaporator 16 to actively utilize the liquid refrigerant for de-icing. By contrast, when the temperature of the liquid refrigerant is low, the liquid refrigerant is not introduced into the evaporator 16 and de-icing can be conducted effectively using only the hot gas. In this connection, the temperature sensor need not necessarily detect the ambient temperature of the external unit 19, and may be provided such that it detects the temperature of a part that changes correspondingly to the temperature of the liquid refrigerant within the refrigerant supply line 18A (i.e., indirectly detects the temperature).
As the first valve device of this invention, instead of the single three-way valve 25 exemplified in the above Embodiments 1 to 3, for example two open/close valves 25A and 25B, which can be individually subjected to open/close control, may be respectively provided on the outlet side of the CPR 23 and on the branch line 21A of the first bypass line 21, as shown in
Further, while the configuration adopted in the above Embodiments 1 to 3 is one in which the condenser fan 12A stops at the time of a de-icing operation, a configuration may be adopted in which the condenser fan 12A continues to be driven even during the de-icing operation.
Embodiment 4 of this invention will now be described referring to
In a cooling system 10B of Embodiment 4 as shown in
Since the remaining structure of the cooling system 10B is the same as the example shown in
The action of Embodiment 4 is described hereunder. As shown in
When entering a de-icing operation, the condenser fan 12A is stopped and the three-way valve 25 on the external side switches to the side of the first bypass line 21. Simultaneously the internal side three-way valve 31 opens to the side of the auxiliary line 30. Thereupon, as shown by an arrow with a dashed line in
As shown by a solid line in
In Embodiment 5, when the temperature of the liquid refrigerant remaining in the refrigerant supply line 18A is relatively high in the cooling system 10 B of
More specifically, when the ambient temperature of the external unit 19 is equal to or greater than a predetermined setting temperature when entering a de-icing operation, the three-way valve 25 on the external side is switched to the side of the first bypass line 21 and simultaneously the internal side three-way valve 31 opens to the side of the evaporator 16, as shown by a dashed line in
In contrast, when the ambient temperature of the external unit 19 is less than the setting temperature, as described above in Embodiment 4, the internal side three-way valve 31 is initially opened to the side of the auxiliary line 30, in order to cause the liquid refrigerant to be collected in the accumulator 17. After the delay time t2 has lapsed, the internal side three-way valve 31 opens to the side of the evaporator 16, whereby hot gas is introduced into the evaporator 16 for de-icing.
For the internal side three-way valve 31 with a shut-off function that is exemplified in Embodiments 4 and 5 above, the timing for switching from a closed state to opening to the auxiliary line 30 may be set to precede the entry into a de-icing operation by the amount of the delay time t2.
Further, in place of the internal side three-way valve 31 with a shut-off function, two open/close valves 31A and 31B, for example, as shown in
Also, in the above Embodiments 4 and 5, a configuration may be adopted in which the condenser fan 12A continues to be driven even during the de-icing operation.
Since the remaining structure is the same as the example shown in
The action of Embodiment 6 is described hereunder. As shown in
When the final stage of the ice making operation is reached, more specifically, when a timing is reached that precedes the starting time for a de-icing operation by a predetermined delay time t3 (e.g., from several seconds to several tens of seconds), the three-way valve 35 switches to the side of the auxiliary line 37 based on a signal from the valve controller 50. As shown by an arrow with a dashed line in
After the delay time t3 lapses the de-icing operation begins, whereby the condenser fan 12A is stopped. The three-way valve 35 switches again to the side of the CPR 23. And, the open/close valve 28 opens. Thus, hot gas from the CPR 23 is introduced into the evaporator 16 through the refrigerant supply line 18A and the second bypass line 27 in order to conduct de-icing.
In this embodiment, because hot gas from the CPR 23 is introduced directly into the evaporator 16 when a de-icing operation has begun, de-icing can be conducted quicker than in the conventional configuration in which hot gas from a CPR is introduced into a receiver to vaporize liquid refrigerant contained therein, and the resulting low-temperature refrigerant gas is then introduced into an evaporator. In addition, depending on conditions such as the outside air temperature, hot gas of a comparatively high temperature can be introduced into the evaporator. Thereby de-icing by manifest heat can also be expected, enhancing the de-icing effect.
Further, in the de-icing operation, when it is desired to conduct de-icing using only hot gas without causing the liquid refrigerant that remains in the refrigerant supply line 18A to be introduced into the evaporator 16, since the configuration is such that liquid refrigerant remaining in the refrigerant supply line 18A is collected in the accumulator 17 through the auxiliary line 37 that is provided in the external unit 19, the collection can be carried out quickly and with a simple structure.
In Embodiment 7, when the temperature of liquid refrigerant remaining in the refrigerant supply line 18A is relatively high in the cooling system 10C of
More specifically, when the ambient temperature of the external unit 19 is equal to or greater than a predetermined setting temperature upon entering a de-icing operation, hot gas is introduced into the evaporator 16 together with liquid refrigerant that was squeezed out from the refrigerant supply line 18A. This occurs when the open/close valve 28 is opened while the three-way valve 35 is connected to the side of the CPR 23.
In contrast, when the ambient temperature is less than the setting temperature, as exemplified in the above Embodiment 6, the three-way valve 35 is initially opened to the side of the auxiliary line 37, causing the liquid refrigerant to be collected in the accumulator 17. After a delay time t3 has lapsed, the three-way valve 35 is connected to the side of the CPR 23 and the open/close valve 28 is opened to allow hot gas to be introduced into the evaporator 16 for de-icing.
Instead of the three-way valve 35 exemplified in the above Embodiments 6 and 7, for example, as shown in
For Embodiments 6 and 7 also, a configuration may be adopted in which the condenser fan 12A continues to be driven during the de-icing operation.
In the following claims, connecting can mean either directly connecting two elements or indirectly connecting two or more elements.