Heat pump unit

Abstract

To prevent the decline in the volumetric efficiency and the decline in the performance of the heat pump having the reciprocating compressor integrated therein by decreasing the temperature of discharge gas in the reciprocating compressor with a simple construction, a heat pump unit 1 constituting a heat pump cycle in which the reciprocating compressor 3 , a condenser 5 , an expansion valve 7 and an evaporator 8 are interposed in a refrigerant circulating path 2 ,comprises a refrigerant-liquid returning path 9 for returning a portion of the refrigerant liquid having been condensed by the condenser 5 to a discharge chamber provided in a cylinder top assembly 20 of the reciprocating compressor 3 so that a portion of the refrigerant liquid is supplied to the discharge chamber 36 via the refrigerant-liquid returning path 9 and a discharge gas passageway 36 a is cooled by evaporative latent heat of the refrigerant liquid.

1 . A heat pump unit comprising:
 a heat pump cycle which includes a reciprocating compressor having a compression part where a piston reciprocates inside a cylinder, a condenser, an expansion valve, and an evaporator provided in a refrigerant circulating path in which NH 3  refrigerant liquid is circulated; and   a first returning path for the refrigerant liquid which returns a portion of the NH 3  refrigerant liquid having been condensed in the condenser to a discharge chamber provided in a cylinder top assembly of the reciprocating compressor or a discharge area that is in communication with the discharge chamber,   wherein the discharge chamber or the discharge area is provided with an injection nozzle connected to the first returning path for the refrigerant liquid such that the NH 3  refrigerant liquid is discharged through the injection nozzle to the discharge chamber or the discharge area.   
     
     
         2 . The heat pump unit according to  claim 1 , further comprising a liquid pump and a pressure-regulating valve located in the first returning path for the refrigerant liquid, and the NH 3  refrigerant liquid which has higher pressure than the discharge chamber is discharged through the injection nozzle to the discharge chamber or the discharge area. 
     
     
         3 . The heat pump unit according to  claim 1 , wherein the reciprocating compressor is a single-stage compressor provided with the injection nozzle in the discharge chamber or the discharge area of the single-stage compressor. 
     
     
         4 . The heat pump unit according to  claim 1 ,
 wherein the reciprocating compressor is a multi-stage compressor including an upper stage compression part and a lower stage compression part, and   the injection nozzle is located in the discharge chamber or the discharge area of the upper stage compression part so as to inject the NH 3  refrigerant liquid through the injection nozzle to the discharge chamber or discharge area of the upper stage compression part.   
     
     
         5 . The heat pump unit according to  claim 4 , further comprising:
 a second returning path for the refrigerant liquid which returns the portion of the NH 3  refrigerant liquid having been discharged from the upper stage compressor part and then condensed in the condenser, to the discharge chamber or discharge area that is in communication with the discharge chamber, the discharge chamber or the discharge area being located in the lower stage compression part;
 wherein the portion of the NH 3  refrigerant liquid is led to be returned to the discharge chamber or discharge area of the lower stage compression part via the second returning path. 
   
     
     
         6 . The heat pump unit according to  claim 5 , further comprising a heat exchanger for the refrigerant liquid which is provided in the refrigerant circulating path between the condenser and the expansion valve, the heat exchanger being connected to the refrigerant circulating path so that refrigerant gas discharged from the lower stage compressor is introduced to the intake chamber or intake area of the upper stage compressor through the heat exchanger, the refrigerant liquid from the condenser being cooled with the refrigerant gas discharged from the lower stage compressor. 
     
     
         7 . The heat pump unit according to  claim 6 , further comprising a heat exchanger for the refrigerant liquid provided in the refrigerant circulating path in an upstream side of the second returning path,
 wherein a portion of the refrigerant liquid having been cooled in the heat exchanger is supplied to the first or second returning path.   
     
     
         8 . The heat pump unit according to  claim 1 , wherein the reciprocating compressor is for refrigerant and comprises an intake chamber in communication with a cylinder via an intake valve at a cylinder top assembly and a discharge chamber in communication with the cylinder via a discharge valve,
 wherein the injection nozzle and a supply port for refrigerant liquid are arranged in the discharge chamber or discharge area, and the injection nozzle is connected to the supply port for the refrigerant liquid, and   wherein the refrigerant liquid is injected through the injection nozzle to the discharge chamber or discharge area.