JPH06281286A - Waste heat recovering device for engine-driven heat pump - Google Patents

Abstract

PURPOSE:To provide a waste heat recovering device for an engine-driven heat pump in which engine waste heat recovering amount can be increased while maintaining excellent engine performance. CONSTITUTION:A water heat recovering device for an engine-driven heat pump comprises two systems of a first warm water circuit 20 for codling an engine body 1, and a second warm water circuit 21 for circulating to a waste gas heat exchanger 22 of the engine 1 and a refrigerant heat exchanger 35 provided in a refrigerant circuit 15. Individual circulating motor-driven pumps 23, 24 are respectively provided in the circuits 20 and 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust heat recovery device for an engine driven heat pump device which increases the amount of exhaust heat recovery of the engine and stabilizes the heating of the refrigerant by the exhaust heat.

[0002]

2. Description of the Related Art In an engine driven heat pump device, the capacity of a refrigeration cycle can be improved by utilizing exhaust heat of an engine for heating a refrigerant. Exhaust heat recovery from the engine is not limited to recovery from engine cooling water,
It can also be performed from exhaust gas by providing an exhaust gas heat exchanger in the silencer. The amount of heat recovered from such an engine body or exhaust gas heat exchanger can be recovered in a larger amount as the water temperature entering these is lowered.

However, in the case of cooling water for the engine body, in order to maintain the best engine performance, it is necessary to set the difference between the inlet water temperature and the outlet water temperature to about 10 ° C. Therefore, when the engine cooling water circuit of the engine body and the exhaust gas heat exchanger are connected in series as a hot water circuit, the inlet water temperature cannot be lowered so much, and therefore there is a limit to recovering a large amount of engine exhaust heat. was there.

As a measure against such a problem, in order to increase the recovery amount of the engine exhaust heat, the hot water circuit is divided into two systems, an engine cooling water circuit and a circuit for circulating an exhaust gas heat exchanger. Is desirable. However, since the circulation pump provided in the cooling water circuit of the engine body generally obtains power from the crankshaft, the flow rate changes due to changes in the engine speed, which adversely affects the external system. Prone.

Further, in the conventional hot water circuit using the exhaust gas heat exchanger, the flow of hot water for heating the refrigerant is controlled by the solenoid valve and the thermostat, so that on / off control is performed, and therefore the refrigerant is heated. There was a problem that the refrigeration cycle was hunted and was not stable because it was clearly divided into the time when it was heated and the time when it was not heated.

[0006]

SUMMARY OF THE INVENTION The first object of the present invention is to provide an exhaust heat recovery device for an engine driven heat pump device which can increase the recovery amount of engine exhaust heat while maintaining good engine performance. The second purpose is to recover the exhaust heat of the engine-driven heat pump device so as to improve the stability and capacity of the refrigeration cycle by enabling stable heating of the refrigerant by the exhaust heat of the engine. To provide a device.

[0007]

SUMMARY OF THE INVENTION The present invention for achieving the above object provides an engine-driven heat pump device in which a compressor is driven by an engine, and a refrigerant is compressed by the compressor and circulated in a refrigerant circuit. As a separate system, a first hot water circuit for cooling the engine body and a second hot water circuit for circulating an exhaust gas heat exchanger of the engine and a refrigerant heat exchanger provided in the refrigerant circuit are separately provided. The first hot water circuit and the second hot water circuit are provided with separate circulating electric pumps, respectively.

Further, in the present invention, in the second hot water circuit having the above structure, the hot water flowing from the exhaust gas heat exchanger to the refrigerant heat exchanger via linear valves whose valve openings are changed steplessly. It is characterized in that it is branched into a path and a hot water path toward the heat radiating heat exchanger, and the valve openings of the two linear valves are controlled steplessly according to the load of the refrigeration cycle.

By dividing the hot water circuit into two systems, the first hot water circuit for cooling the engine body and the second hot water circuit for the exhaust gas heat exchanger and the refrigerant heat exchanger, the water temperature of the first hot water circuit is increased. Since the water temperature of the second hot water circuit can be set low while increasing the engine temperature, it is possible to increase the recovery amount of the engine exhaust heat for heating the refrigerant while maintaining good engine performance. Moreover, since the circulation pumps of the first and second hot water circuits are independent electric pumps, the hot water flow rate is not influenced by the engine speed.

In the second hot water circuit, the valves for controlling the hot water flow rate to the refrigerant heat exchanger and the hot water flow rate to the heat radiation heat exchanger are linear valves, and the valve opening of the linear valve is the load of the refrigeration cycle. Since the control is performed steplessly in accordance with the above, the heating of the refrigerant by the engine exhaust heat is stabilized, and the stability and capacity of the refrigeration cycle can be improved. The present invention will be described below with reference to the embodiments shown in the drawings.

In FIG. 1, reference numeral 1 is an engine, and two compressors 2 are driven by the engine 1. The compressor 2 compresses the refrigerant and circulates it in the refrigerant circuit 15. The refrigerant circuit 15 is
The circuit forming between the compressor 2 and the four-way valve 5 is the compressor 2
Discharge circuit 3 that sends out the refrigerant discharged from the four-way valve 5
And a suction circuit 4 for returning the refrigerant flowing back from the four-way valve 5 to the compressor 2. An oil separator 6 for separating oil in the refrigerant is connected in the middle of the discharge circuit 3,
Further, in the middle of the suction circuit 4, accumulators 7 and 8 for temporarily storing the liquid-phase refrigerant are connected.

The refrigerant circulation circuit extending from the four-way valve 5 is formed in an annular shape via the pipe lines 9, 10 and 11, and an indoor heat exchanger 12 and an outdoor heat exchanger 13 are connected in the middle thereof.
This refrigerant circulation circuit becomes a heating cycle when the refrigerant is circulated in the direction of the solid arrow W by switching the four-way valve 5.
Further, when the air is circulated in the direction of the broken arrow C, the cooling cycle is started. The number of indoor heat exchangers 12 is not limited to one, and if necessary, a plurality of indoor heat exchangers may be connected to form a multi-system as shown by a chain line in the figure. Further, an outdoor fan 14 is provided opposite to the outdoor heat exchanger 13.

Reference numeral 20 is a first hot water circuit forming a cooling water circuit of the engine 1. Further, 22 is an exhaust gas heat exchanger provided in the silencer of the engine 1, and this exhaust gas heat exchanger 2
A second hot water circuit 21 in which hot water circulates 2 is provided. As the circulation pump of these two hot water circuits,
The hot water circuit 20 is provided with an electric pump 23, and the second hot water circuit 21 is provided with an electric pump 24.

The first hot water circuit 20 and the second hot water circuit 21 are connected by pipelines 25 and 26 and a three-way valve 27. The engine cooling water in the first hot water circuit 20 is always circulated only in the first hot water circuit 20 by the three-way valve 27, and is maintained at a comparatively high water temperature. However, when the engine cooling water reaches or exceeds the predetermined set temperature, the three-way valve 27 is automatically switched to the side of the pipe line 26, a part of the engine cooling water flows out to the second hot water circuit 21, and the pipe line 2 is turned on the contrary.
The low-temperature hot water in the second hot-water circuit 21 flows in through 5.

In the second hot water circuit 21, a conduit 28 for sending hot water from the exhaust gas heat exchanger 22 is branched into conduits 31 and 32 via linear valves 33 and 34, respectively. One of the conduits 31 is returned to the conduit 29 that returns to the exhaust gas heat exchanger 22 again via the refrigerant heat exchanger 35 provided in the liquid phase refrigerant of the accumulator 7 in the refrigerant circuit 15. There is. The other conduit 32 is also designed to flow back to the conduit 29 to the exhaust gas heat exchanger 22 via the heat dissipation heat exchanger 36 provided outdoors.

The linear valves 33 and 34 are flow rate control valves which are constructed so that the valve openings can be changed steplessly. The valve openings of these linear valves 33 and 34 are controlled by a control unit 40 and a data storage unit 41 which are configured by a microcomputer. That is, the control unit 40 has
Various signals that are substitute values for the load of the refrigeration cycle as described below are input, and the amount of heat to be given to the refrigerant to maximize the capacity of the refrigeration cycle is determined according to those load conditions, and corresponding to it. Hot water flow rate is linear valve 3
The valve opening degrees Sa and Sb of the valves 3 and 34 are output.

As a signal which is a substitute value of the load of the refrigeration cycle, the throttle opening S of the engine 1 from the sensor 42 is used.
t, the rotational speed Nc of the compressor from the sensor 43, the temperature Tw of the cooling water from the temperature sensor 44 (thermistor) on the outlet side of the exhaust gas heat exchanger 22, the temperature sensor 45 (thermistor) provided in the low pressure saturation detection circuit 4 ′ of the refrigerant circuit. From the low pressure saturation temperature Ts of the refrigerant, the temperature sensor 46 (thermistor) installed in the outside air to the outside air temperature To, the sensor 47 installed in the outdoor fan 14 to the outdoor fan rotation speed Nf, and the linear valves 33 and 34 from the valve opening degree Sw1. , Sw2 are input.

Linear valves 33, 3 output from the control unit 40
The valve openings Sa and Sb of No. 4 are determined by using data stored in advance in the data storage unit 41, for example, according to a flowchart as shown in FIG. First, the load is checked by looking at St and Nc (101), and the required heat quantity Qr is calculated (102). Next, based on Tw, Ts and Sw1, calculation of the heat quantity Qg supplied to the current refrigerant (103) and calculation of the heat radiation quantity Qt (104) based on Tw, To, Nf and Sw2 are carried out to predict the cooling water temperature Tw (10).
5). Fuzzy inference is performed based on the predicted cooling water temperature Tw, the required heat quantity Qr, the supplied heat quantity Qg, and the heat radiation quantity Qt (106), and the valve opening degrees Sa and Sb to be output are determined (107).

Linear valves 33, 34 based on such signals
Since the appropriate flow rate of hot water according to the load flows into the refrigerant heat exchanger 35 by controlling the valve opening degree, the stability of the refrigeration cycle and the capacity can be improved.

[0020]

As described above, according to the present invention, the hot water circuit is divided into two systems, the first hot water circuit for the engine body and the second hot water circuit for the exhaust gas heat exchanger and the refrigerant heat exchanger. Therefore, while the water temperature of the first hot water circuit can be set high while the water temperature of the second hot water circuit can be set low, the recovery amount of the engine exhaust heat can be increased while maintaining good engine performance. Moreover, since the circulation pumps of the first and second hot water circuits are electric pumps, the hot water flow rate can be stabilized without being affected by the engine speed.

Further, the flow rate of hot water to the refrigerant heat exchanger and the heat radiating heat exchanger in the second hot water circuit is controlled by the linear valve, and the valve opening thereof is controlled in accordance with the load of the refrigeration cycle. It is possible to stabilize the heating of the refrigerant by the exhaust heat of the engine and to improve the stability and performance of the refrigeration cycle.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an example of an exhaust heat recovery device of an engine-driven heat pump device according to the present invention.

FIG. 2 is a flowchart showing an example of valve opening control of a linear valve.

[Explanation of symbols]

1 Engine 2 Compressor 7 Accumulator 15 Refrigerant Circuit 20 First Hot Water Circuit 21 Second Hot Water Circuit 22 Exhaust Gas Heat Exchanger 23, 2
4 Electric Pump 33, 34 Linear Valve 35 Refrigerant Heat Exchanger 36 Heat Dissipation Heat Exchanger 40 Control Section 41 Data Storage Section

Claims (2)

[Claims] 1. A first hot water circuit that cools the engine body as a hot water circuit in an engine-driven heat pump device in which a compressor is driven by an engine and refrigerant is compressed by the compressor and circulated in a refrigerant circuit. The engine exhaust gas heat exchanger and the refrigerant heat exchanger provided in the refrigerant circuit are separately provided in two systems of a second hot water circuit that circulates, and the first hot water circuit and the second hot water circuit are individually provided. Exhaust heat recovery device for engine driven heat pump device equipped with electric circulation pump. 2. In the second hot water circuit, a hot water passage extending from the exhaust gas heat exchanger, a hot water passage extending toward the refrigerant heat exchanger through linear valves whose valve openings change steplessly, and a heat radiating heat. The exhaust heat of the engine-driven heat pump device according to claim 1, wherein the exhaust valve is divided into a hot water path toward the exchanger, and the valve openings of the linear valves are controlled steplessly according to the load of the refrigeration cycle. Recovery device.