JP2720996B2 - Engine heat pump defroster - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial application field The present invention relates to an engine heat pump that drives a compressor for cooling and heating by an engine and also uses exhaust heat of the engine for heating. The present invention relates to a defrosting mechanism for removing frost adhering to an outdoor heat exchanger.

(B) Prior art In an engine heat pump, a mechanism for performing defrosting without stopping the operation during a heating operation is disclosed in JP-A-62-2987.
The technique described in Japanese Patent Publication No. 1 is known.

In addition, a technology to branch off from the refrigerant discharge side of the compressor and provide a bypass circuit for defrosting and mix the refrigerant with the main heating circuit to raise the temperature of the refrigerant to the outdoor heat exchanger
The technique described in JP-A-62-91166 is known.

Further, as a technique of heating a refrigerant from an outdoor heat exchanger by a burner, gasifying the refrigerant, and sucking the gas into a compressor, a technique as disclosed in JP-A-59-125362 is known.

(C) Problems to be Solved by the Invention In the present invention, when a bypass from the compressor is provided for defrosting, the refrigerant from the main heating circuit and the refrigerant from the compressor are combined to raise the temperature and pressure. In some cases, the refrigerant after passing through the outdoor heat exchanger is not completely gasified and remains as a liquid refrigerant.

As described above, if the refrigerant is sucked into the compressor in a liquid state, the compressor presses the liquid, thereby lowering the durability and causing damage to each part.

In the present invention, in order to prevent such a problem from occurring, an exhaust heat recovery device of the engine is disposed in a circuit subsequent to the outdoor heat exchanger 18 so that the liquid in the refrigerant used for the defrost is completely gasified. It is configured to be

Also, in a configuration in which one compressor sends refrigerant to two indoor heat exchangers, when one of the two indoor heat exchangers is suddenly stopped, the amount of refrigerant discharged from the compressor 2 is reduced. Is instantaneously concentrated on one unit and becomes excessive, so that the remaining one indoor heat exchanger is overloaded.

In this way, when one indoor heat exchanger 40 is stopped, a bypass circuit capable of allowing excess refrigerant to escape is provided.
This is also provided for the defrost bypass circuit A.

Also, in the defrost device of the engine heat pump,
Since the exhaust heat recovery unit 10 is provided, the evaporation temperature te of the refrigerant does not decrease,
Since the temperature difference Δt does not become large, there is a problem that even if frost adheres to the outdoor heat exchanger 18, it cannot be detected.

That is, when one indoor heat exchanger 4 is provided, half of the refrigerant discharged from the compressor 2 is supplied to the defrost bypass circuit A.
Then, the refrigerant passes through the solenoid valve 5 and returns to the compressor 2 from the four-way switching valve 6, so that the amount of refrigerant to the outdoor heat exchanger 18 is small, so that the temperature difference Δt does not increase.

Therefore, it cannot be accurately detected whether frost is present.

In this case, if frost adheres to the outdoor heat exchanger 18, the cooling air does not pass through the radiator juxtaposed to the outdoor heat exchanger 18, so that the temperature of the engine coolant increases.

In the present invention, the rise of the cooling water temperature is detected to detect the adhesion of frost, and the defrosting bypass circuit A is opened to perform the defrosting control.

(D) Means for Solving the Problems The object of the present invention is as described above, and a configuration for achieving the object will be described below.

According to claim (1), in the engine heat pump used for heating while the compressor 2 for cooling and heating is driven by the engine and the exhaust heat of the engine is collected by the exhaust heat recovery unit 10, the discharge side of the compressor 2 is used. And a bypass circuit A for defrost branched from between the and the four-way switching valve 6, and the heating expansion valve 22, the outdoor heat exchanger 18, and the exhaust heat recovery unit 10 are connected in series in the direction in which the refrigerant flows during heating. The defrosting bypass circuit A constitutes a main heating circuit disposed therein, and the defrosting bypass circuit A joins between the heating expansion valve 22 and the outdoor heat exchanger 18. With valve 9 interposed
The defrost bypass circuit A mixes the refrigerant from the compressor 2 with the refrigerant in the main heating circuit, raises and raises the temperature of the refrigerant to the outdoor heat exchanger 18, and removes frost adhering to the outdoor heat exchanger 18. In addition to performing the frost, the refrigerant from the outdoor heat exchanger 18 is passed through the exhaust heat recovery unit 10, and the refrigerant is gasified as heated steam and is sucked by the compressor 2.

According to claim (2), in the defroster for an engine heat pump according to claim (1), the number of the indoor heat exchangers 40 in which a plurality of bypass circuits A for defrost are juxtaposed during the heating operation is suddenly increased. When the number of refrigerants decreases, a part of the refrigerant is also used as a circuit for merging from the compressor 2 to the main heating circuit between the heating expansion valve 22 and the outdoor heat exchanger 18 and returning to the compressor 2.

According to claim (3), in the defroster for an engine heat pump according to claim (1), the temperature difference Δt between the outside air temperature ta and the evaporation temperature te is equal to or more than a set value and the evaporating temperature te is equal to or less than a set value, or When the number of the indoor heat exchangers 40 is reduced, the engine cooling water temperature T is equal to or higher than the set value and the outside air temperature ta.
Is set to a set value or less, the defrost bypass circuit A is opened to start defrosting.

(E) Embodiment The purpose and configuration of the present invention are as described above. Next, the configuration of the embodiment shown in the accompanying drawings will be described.

FIG. 1 is a refrigerant circuit diagram of an engine heat pump that sends a refrigerant to two indoor heat exchangers by one compressor.

 In FIG. 1, the flow of the refrigerant during cooling will be described.

The compressor 1 is driven by the engine 1 to convert the refrigerant into high-temperature and high-pressure superheated steam, pass through the oil separator 4 and separate oil.

The refrigerant in the high-temperature, high-pressure superheated vapor state after the separation of the oil is guided to the four-way switching valve 6, and from the four-way switching valve 6 via a pipe passing through the exhaust heat recovery unit 10, the outdoor heat exchanger Pass through 18.

While passing through the outdoor heat exchanger 18, the refrigerant emits heat from a high-temperature, high-pressure superheated vapor state and is converted into a high-pressure liquid state, and upon condensation from the vapor into a liquid, the refrigerant releases heat to the atmosphere. I do.

The high-pressure liquid state refrigerant that has passed through the outdoor heat exchanger 18 passes through the check valve 32 without passing through the heating expansion valve 22, and enters the liquid receiver 20. In the liquid receiver 20, the gaseous phase refrigerant is separated, and only the refrigerant in a high-pressure liquid state is supplied to the cooling expansion valves 24a and 24b. The cooling expansion valves 24a, 2
In 4b, the refrigerant expands rapidly, and the refrigerant in the high-pressure liquid state becomes a low-temperature, low-pressure vapor state, and the indoor heat exchangers 40a, 40
The refrigerant absorbs indoor heat while passing through b, and the low-temperature and low-pressure refrigerant turns into superheated steam and passes through the two solenoid valves 12a and 12b for switching the indoor heat exchangers 40a and 40b. One-way switching valve 6
Return to

The refrigerant enters the accumulator 8 by the four-way switching valve 6 and completely returns the refrigerant to the compressor 2 after being brought into the gaseous state. This cycle is repeated to cool the room.

 Next, the flow of the refrigerant during heating will be described.

In FIG. 1, the arrows shown in the refrigerant circuit indicate the flow of the refrigerant during heating.

In this case, the four-way switching valve 6 is switched from refrigerant to heating.

A high-temperature, high-pressure superheated vapor state refrigerant is discharged from a compressor 2 driven by an engine 1, and the oil is separated by an oil separator 4.
The high-pressure superheated vapor refrigerant flows from the four-way switching valve 6 to the solenoid valve 13.
After passing through a and 13b, they reach the indoor heat exchangers 40a and 40b.
In the indoor heat exchangers 40a and 40b, the refrigerant in a high-temperature and high-pressure excess vapor state emits heat to the indoor air, and the refrigerant becomes a high-pressure liquid state.

The refrigerant in the high-pressure liquid state does not pass through the cooling expansion valves 24a, 24b, passes through the check valves 34a, 34b, enters the liquid receiver 20, and separates the gas-phase refrigerant by the liquid receiver 20, and Only the refrigerant in the phase passes through the heating expansion valve 22.

In the heating expansion valve 22, the refrigerant in the high-pressure liquid state rapidly expands to a low-temperature, low-pressure vapor state, and the outdoor heat exchanger
While passing through 18, heat is obtained from the outside air to become overheated steam.

At this time, if the temperature of the outside air is low and it is not possible to obtain heat enough to convert the sufficiently low-temperature and low-pressure steam state into overheated steam, by passing through the exhaust heat recovery unit 10, It returns to completely superheated steam.

The superheated steam enters the accumulator 8 from the four-way switching valve 6, returns to the compressor 2 after being completely in the vapor phase in the accumulator 8.

Then, in the heating circuit, this cooling cycle is repeated.

In the case of a cooling circuit, the exhaust heat recovery device 10 switches the thermostat valve so as not to serve the function of supplying heat.

The present invention constitutes a defrost bypass circuit A that branches off at the outlet of the compressor 2 and does not pass through the four-way switching valve 6 or the indoor heat exchangers 40a and 40b.

Then, the evaporation temperature te, which is the temperature of the refrigerant coil, which is a condition for constant defrosting, is equal to or less than -3 ° C, and
When the temperature difference Δt of te is 7 ° C. or more, the defrosting operation is started.

When performing the defrosting operation, first, the electromagnetic valve 44 in FIG. 1 is opened.

As a result, the high temperature discharged from the compressor 2
A part of the refrigerant of the high-pressure superheated steam flows from the defrosting bypass circuit A to the circuit of the solenoid valve 44, passes through the indoor heat exchangers 40a and 40b, and passes through the heating expansion valve 22, and the low-temperature and low-pressure steam state. Of the refrigerant. This allows the outdoor heat exchanger 18
The temperature of the low-temperature, low-pressure vapor refrigerant passing through the heat exchanger is increased by the high-temperature, high-pressure heating steam.
It removes frost from the surface.

After the completion of the defrosting operation, the solenoid valve 44 closes, and the refrigerant does not pass through the defrosting bypass circuit A.

A check valve 9 is interposed in the circuit of the solenoid valve 44,
Because the circuit of the solenoid valve 44 is configured, during the cooling operation, the refrigerant that has passed through the outdoor heat exchanger 18 returns from the solenoid valve 44 to the accumulator 8 through the defrost bypass circuit A. It is a check that there is no such thing.

Next, from the use state of two indoor heat exchangers 40a and 40b,
The operation when the number of vehicles suddenly decreases to one will be described.

In this case, both the solenoid valve 5 and the solenoid valve 44 provided in the defrost bypass circuit A are simultaneously opened. However, the circuit of the solenoid valve 44 is only the check valve 9, and the circuit of the solenoid valve 5 is provided with the check valves 7, 12 and the capillary tubes 15, 45. Although the flow mainly flows in the direction of 9, the solenoid valve 44 closes in about 30 seconds and thereafter returns from the capillary tube 15 to the accumulator 8 via the check valve 7.

Thereby, the high temperature discharged from the compressor 2
A part of the high-pressure heated steam refrigerant is circulated by the short circuit, and a large amount of the refrigerant passes through the indoor heat exchanger 40 in which one unit is in use.
It is possible to suppress generation of an unstable cooling / heating control state.

In the case of cooling, the solenoid valve 5
Cooling passed through the check valve 12 and the capillary tube 45
After that, the process returns to the accumulator 8.

FIG. 2 is a drawing showing an increase in the temperature of the radiator 17, and FIG. 3 is a flowchart showing a defrosting operation condition in a special state.

In addition to the condition that the temperature of the refrigerant coil that is the condition for starting the normal defrosting operation, that is, the evaporation temperature te is −3 ° C. or less and the outside air temperature ta−evaporation temperature te−temperature difference Δt is 7 ° C. or more,
When the refrigerant from one compressor 2 is supplied to the two indoor heat exchangers 40a and 40b, the state of adhering frost may not be determined. It is controlling to start.

That is, when the number of the indoor heat exchangers 40 is reduced, and the engine cooling water temperature T rises above the set value of about 94 ° C. and the outside air temperature ta falls below the set value of 1 ° C. It is.

Separately, the above case is provided as a special defrosting condition because, in the defroster of the engine heat pump, since the exhaust heat recovery unit 10 is provided, the evaporation temperature te, which is the refrigerant coil temperature.
However, even if the temperature does not drop below −3 ° C. and the temperature difference Δt does not become 7 ° C. or more, frost may adhere.

Further, in the mechanism in which the refrigerant is supplied to the two indoor heat exchangers 40a and 40b by one compressor 2, when the number of the indoor heat exchangers 40 is one, the electromagnetic valve 5 is opened as described above. Since a part of the refrigerant is returned to the compressor 2, the amount of the refrigerant is halved, and even if the evaporation temperature te does not become lower than −3 ° C. and the temperature difference Δt does not become higher than 7 ° C., frost may adhere. .

If the frost adheres to the defrosting condition without the evaporating temperature te and the temperature difference Δt not agreeing with each other, the fins of the outdoor heat exchanger 18 close the gap with the frost, and the cooling discharged by the fan 16 Radiator 17 in which wind overlaps outdoor heat exchanger 18
, The temperature of the cooling water of the radiator rises.

The cooling water temperature of the radiator is set to a fixed value, that is, 94 ° C., and when it rises more than that, a defrosting operation is started.

In FIG. 2, reference numerals 21 and 25 denote solenoid valves, and reference numerals 23 and 26 denote check valves, which are switched depending on the temperature of the outside air when passing or not passing through the exhaust heat recovery unit 10. Reference numeral 45 denotes an exhaust heat recovery device.

FIG. 4 shows an arrangement in which the outdoor heat exchanger 18 and the exhaust heat recovery unit 10 are arranged in parallel, and high-temperature and high-pressure heating steam flows directly from the compressor 2 to the outdoor heat exchanger 18 to perform defrosting operation and exhaust. FIG. 5 is a refrigerant circuit showing a heating operation state of the circuit shown in FIG. 4, and FIG. FIG. 5 is a refrigerant circuit diagram showing a refrigerant operation state of the circuit of FIG. 4.

First, in the cooling operation shown in FIG. 6, a check valve 39 and a solenoid valve 29 are interposed in the circuit of the exhaust heat recovery device 10 among the outdoor heat exchanger 18 and the exhaust heat recovery device 10 arranged in parallel. , So that the refrigerant does not pass through.

 Other circuits are the same as those in FIG.

Next, in the heating operation of FIG. 5, the refrigerant from the liquid receiver 20 is branched to both the heating expansion valve 22 and the exhaust heat recovery device expansion valve 27 via the filter 28 and the solenoid valve 29. Then, both the outdoor heat exchanger 18 and the exhaust heat recovery unit 10 are brought into a low-temperature and low-pressure steam state, and return to the compressor 2.

Therefore, in this case, the outdoor heat exchanger 18 and the exhaust heat recovery
Are arranged in parallel, but both act as heat sources.

 Next, the operation in the defrosting operation state shown in FIG. 4 will be described.

In this case, heat is released in the outdoor heat exchanger 18 to perform defrosting, and the defrosting is performed by the exhaust heat recovery device expansion valve 27 for defrosting.
The defrost circuit is specially configured to be in a low-pressure steam state and to absorb heat in the exhaust heat recovery unit 10 to become a heated steam.

Solenoid valve 31, check valve 33, 38, capillary tube 37, 35
Is a circuit for returning a part of the high-temperature and high-pressure heating steam when one of the indoor heat exchangers 40a and 40b is stopped.

The circuit of the solenoid valve 11 and the expansion valve 30 is a refrigerant circuit used to appropriately maintain the heating state of the refrigerant sucked into the compressor 2 when the number of the indoor heat exchangers 40 decreases.

(F) Effects of the Invention The present invention is configured as described above, and has the following effects.

Since the main heating circuit is constituted by the heating expansion valve 22, the outdoor heat exchanger 18, and the exhaust heat recovery unit 10, the refrigerant from the defrost bypass circuit A is configured as described in claim (1). ,
The exhaust heat recovery unit is joined while being joined between the heating expansion valve 22 and the outdoor heat exchanger 18 to perform the defrost operation of the outdoor heat exchanger 18.
Because the ten parts were arranged in series, it was possible to continue the normal heating state.

Further, when the defrosting operation is started, the refrigerant flows through the defrosting bypass circuit A, so that the load is lightened, the engine speed is increased, and the temperature of the exhaust heat recovery unit 10 is also increased. The overheating capacity of the entire system increases, the heating capacity increases, and the defrosting action can be performed quickly.

In addition, since the refrigerant is completely gasified by the increase in the overheating capacity, the compressor 2 can be prevented from being damaged when the refrigerant in the liquid state flows into the compressor 2.

In addition, since the check valve 9 is interposed in the defrost bypass circuit A, the defrost bypass circuit A is configured.
During the cooling operation, the refrigerant that has passed through the outdoor heat exchanger 18 attempts to return to the accumulator 8 from the gap of the electromagnetic valve 44 through the neutralization bypass circuit A, but this can be prevented. It is possible to prevent a decrease in efficiency.

With the configuration as claimed in claim (2), in the case of a configuration in which two indoor heat exchangers 40a and 40b are operated by one compressor 2, when one indoor heat exchanger 40 is suddenly stopped. , A large amount of refrigerant remains in one indoor heat exchanger 40
The problem of overheating and overcooling occurring due to concentration in the system and instability of temperature control could be solved by short-circuiting part of the refrigerant and returning it to the compressor 2. is there.

Also, at the time of heating, only the circuit from the solenoid valve 5 to the check valves 7 and 12 is insufficient for the short circuit of the refrigerant immediately after the stop, but the defrost circuit from the solenoid valve 44 to the check valve 9 is replaced by the short circuit. As a part of the above, the short circuit for surplus refrigerant can be shared by the bypass circuit A for defrost by using only a short time.

Since the exhaust heat recovery device 10 is provided because the heat pump is an engine heat pump, the evaporation temperature te does not decrease and one indoor heat exchanger 40 is stopped. Since a part of the refrigerant is returned to the compressor 2 using the bypass circuit A for defrosting and the short circuit of the solenoid valve 5, the temperature of the evaporation temperature te does not decrease in the outdoor heat exchanger 18 and the temperature difference Δt is reduced. Although the temperature does not drop below the set value, the condition that frost still adheres to the outdoor heat exchanger 18 occurs. Thereby, the adhesion of frost can be sensed.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of an engine heat pump that sends refrigerant to two indoor heat exchangers by one compressor, FIG. 2 is a drawing showing an increase in the temperature of a radiator 17, and FIG. Flow chart showing frost operation conditions, fourth
In the figure, the outdoor heat exchanger 18 and the exhaust heat recovery unit 10 are arranged in parallel,
A refrigerant circuit showing a defrosting operation state, in which high-temperature and high-pressure heating steam is directly supplied from the compressor 2 to the outdoor heat exchanger 18 to perform a defrosting operation, and the exhaust heat recovery unit 10 converts the steam into a heated state. FIG. 5 is a refrigerant circuit diagram showing a heating operation state of the circuit of FIG. 4, and FIG. 6 is a refrigerant circuit diagram showing a cooling operation state of the circuit of FIG. A: Defrost bypass circuit 1: Engine 2: Compressor 10: Exhaust heat recovery unit 17: Radiator 18: Outdoor heat exchangers 40a, 40b: Indoor heat exchanger

Claims (3)

(57) [Claims] An engine drives an air conditioner / compressor and an exhaust heat of the engine.
In the engine heat pump used for heating and recovered by the compressor, the discharge side of the compressor 2 and the four-way switching valve 6
And a main heating circuit in which a heating expansion valve 22, an outdoor heat exchanger 18, and an exhaust heat recovery device 10 are arranged in series in a direction in which the refrigerant flows during heating. The defrosting bypass circuit A is joined between the heating expansion valve 22 and the outdoor heat exchanger 18, and the solenoid valve 44 and the check valve 9 are interposed in the defrosting bypass circuit A. The defrosting bypass circuit A mixes the refrigerant from the compressor 2 with the refrigerant in the main heating circuit, raises and raises the temperature of the refrigerant to the outdoor heat exchanger 18, and removes the frost adhering to the outdoor heat exchanger 18. Defrosting of the engine heat pump, wherein the defrosting is performed, the refrigerant from the outdoor heat exchanger 18 is passed through the exhaust heat recovery unit 10, the refrigerant is gasified as steam in a heated state, and the refrigerant is sucked into the compressor 2. apparatus. 2. The defrosting device for an engine heat pump according to claim 1, wherein a plurality of indoor heat exchangers 40 arranged in parallel with the defrosting bypass circuit A suddenly decrease during the heating operation. A part of the refrigerant from the compressor 2 to a main heating circuit between the heating expansion valve 22 and the outdoor heat exchanger 18 and a circuit for returning the refrigerant to the compressor 2. Defrosting device. 3. The defroster for an engine heat pump according to claim 1, wherein the temperature difference Δt between the outside air temperature ta and the evaporation temperature te is equal to or greater than a set value and the evaporation temperature te is equal to or less than the set value, or indoor heat exchange. When the engine cooling water temperature T is equal to or higher than the set value and the outside air temperature ta is equal to or lower than the set value when the number of the heaters 40 is reduced, the defrosting bypass circuit A is opened to start defrosting. A defroster for an engine heat pump.