GB2030218A

GB2030218A - Heat extraction from i.c. engine and refrigerant compressor apparatus

Info

Publication number: GB2030218A
Application number: GB7925398A
Authority: GB
Original assignee: Sachs Systemtechnik GmbH
Current assignee: Sachs Systemtechnik GmbH
Priority date: 1978-07-20
Filing date: 1979-07-20
Publication date: 1980-04-02
Also published as: GB2030218B; DE2831879A1; SE7906218L; FR2436343A1; FR2436343B3

Abstract

Heat evolved during operation of the engine 1 and the compressor 2 of a heat pump installation is transferred to a building hot water heating circuit. Water entering the inlet 18 cools refrigerant in the compressor outlet chamber 20, the engine cylinder and compressor cylinder in flowing through chambers 22 and 23 and the engine exhaust gas in ducts 25 and 26. The duct 26 surrounds the engine and compressor cylinders and is closed by covers (29), Figs. 2 and 3 (not shown), at the sides of the unit. <IMAGE>

Description

SPECIFICATION Heat-pump drive The invention relates to a heat-pump drive, consisting of an internal combustion reciprocating piston engine connected to a reciprocating piston compressor and heat exchangers are provided to dissipate the heat evolved during the working process and this heat is fed to a heat receiver, at least one heat exchanger being provided inside the reciprocating piston engine.

A refrigerating compressor is known, which is coupled directly to a multi-cylinder Diesel engine, one of the Diesel engine cylinders being replaced by a refrigerating compressor. A heating installation is also known, which is constructed as a heat pump and which comprises a compressor driven by an internal combustion engine, followed by a heatexchanger carrying the internal combustion engine exhaust gases. This exhaust-gas heat-exchanger is incorporated in the exhaust-gas pipe separately from the engine casing, and the heat recovered from the exhaust gases is utilized for heating purposes. A disadvantage of this system is that the separate arrangement of the exhaust-gas heat-exchanger is not only very expensive, but also requires a very large number of components and occupies a considerable amount of space.

In the heat pumps known today for the energysaving heating and hot-water supply of buildings, said pumps being driven by internal combustion engines, the internal combustion engine is conventionally connected to the compressor via a belt drive or a shaft coupling. The internal combustion engine is cooled by the water circuit used for the heating of the building. As already stated hereinbefore, it is known to provide an additional heat exchanger in the heating circuit, this heat exchanger carrying a flow of the exhaust gases.

The object of this invention is to provide a heatpump drive consisting of an internal combustion reciprocating piston engine and a reciprocating piston compressor, in which good utilization of the heat evolved by the internal combustion engine and the compressor is ensured, which guarantees inexpensive manufacture, had a compact and simple construction, and ensures perfect cooling of the internal combustion engine and of the compressor, and good silencing.

To this end, according to the invention, an exhaust-gas heat-exchanger carrying the internal combustion engine exhaust gases is provided in the engine in addition to the heat-exchanger which cools the engine. The fact that the exhaust gas heatexchanger is integrated in the internal combustion engine casing provides a compact and simple construction for the complete unit, good utilization of the heat evolved by the internal combustion engine being guarateed. The heat-pump installation is also cheaper two manufacture and has good silencing.

Since internal combustion engine casings are made as castings, the exhaust gas heat-exchanger may be disposed in the internal combustion engine casing at any point.

According to one feature of the invention, the exhaust gas heat-exchanger is disposed preferably in the cylinder and/or in the cylinder head, the cylinder or cylinder head being provided with an additional heat-exchanger circuit which not only allows intensive heat exchange with the heat receiver, but also gives good silencing of the noise produced by the internal combustion engine. The provision of two separate heat-exchanger circuits allows easy temperature control and also has the advantage that the colder exchanger parts are disposed near the outer surface of the internal combustion engine.

The invention shows that the heat-pump drive costs can be greatly reduced by integrating the exhaust gas heat exchanger with the heat exchanger which cools the internal combustion engine cylinder and cylinder head, and by the two heat exchangers having common coolant circuit. A considerable proportion of the heat energy contained in the exhaust gases is fed to the heat receiver, i.e. the heating circuit or the hot-water circuit. Since the heating circuit generally contains a circulating pump, no additional water pump is required for the internal combustion engine coolant circuit which, naturally, represents the heating circuit.

According to the invention, a very intensive heat exchange is obtained as a result of the fact that the exhaust-gas heat-exchanger ducts carrying the exhaust gases are surrounded by coolant on all sides. In order to simplify the form of the internal combustion engine casing for casting purposes, it may be advantageous according to the invention to surround the exhaust gas ducts only partially with liquid. To ensure good heat exchange, according to one feature of the invention, the partition disposed between the exhaust gas ducts and the coolant has ribs projecting into the exhaust gas ducts.

When the internal combustion engine cylinder block is integral with the compressor cylinder block in the heat pump drive, very good utilization of the heat evolved by the internal combustion engine and of the heat evolved by the compressor on compression, is obtained if the exhaust gas heat exchanger and the heat exchanger surround both the internal combustion engine cylinder and the compressor cylinder.

According to a further feature of the invention, the coolant circuit between the two heat exchangers is such that the coolant inlet is disposed on the compressor cylinder and first leads into a liquid duct surrounding the pressure chamber, and at least one duct is provided which leads into the annular chamber surrounding the compressor cylinder, while said annular chamber is connected to the chamber surrounding the internal combustion engine cylinder and a duct leads from this chamber to the internal combustion engine cylinder head. In this way, the coolant flows first through the pressure chamber in the compressor, then through the com pressor cylinder, then through the internal combustion engine cylinder, and finally the internal combustion engine cylinder head.According to the invention, the exhaust gas ducts comprise annular ducts which surround the coolant chambers surrounding the internal combustion engine cylinder and the compressor cylinder. According to the invention, the exhaust gas duct leading from the exhaust valve leads into the annular duct at the farthest possible point away from the compressor cylinder, while the exhaust gas outlet is disposed on that side of the compressor cylinder block which is remote from the internal combustion engine cylinder. This circulation of the coolant and of the exhaust gases provides very good utilization of the heat evolved by the engine and the compressor, while at the same time the heat pump drive construction is very compact and simple.

According to the invention, very good heat exchange is obtained between the internal combustion engine exhaust gases and the coolant if the ribs are disposed only partially on the periphery of the partition and baffle means for the exhaust gases are provided between the cylinders in the zone which is devoid of ribs. Since the exhaust gas ducts disposed in the cylinder block are bounded on the outside by covers fixed on the cylinder block, it is a very easy matter to clean the exhaust gas ducts. Advantageously, the baffle means are disposed on the covers.

Other possible constructions and advantages will be apparent from the description of the construction and operation of the embodiment of the invention shown by way of example in the drawings wherein: Fig. lisa longitudinal section through the heat pump drive.

Fig. 2 is a cross-section through the internal combustion engine part of the heat pump drive on the line ll-ll in Fig. 1.

Fig. 3 is a section on the line Ill-Ill in Fig. 2.

The heat pump drive shown in the Figures consists of an internal combustion reciprocating piston engine 1, which is constructed as a one-cylinder engine and which is shown in the drawings as a Diesel engine. The inlet valve 3 and the exhaust valve 5 are operated via the overhead camshaft 5, which also drives the injection pump 6. The cylinder block7 of the internal combustion engine 1 and the cylinder block 8 of the reciprocating piston compressor 2 are shown as an integral unit and are provided with the cylinder liner for the piston of the internal combustion reciprocating piston engine and the cylinder liner 10 for the compressor piston. The bottom part 13 of the crank case is bolted, in the bearing plane of the crankshaft 11,tithe crank case formed by the cylinder blocks 7 and 8.The connecting rod of the compressor 2 is overhung on a crank plate 12 which is connected to the crank shaft 11 and which has a crankpin.

The cylinder head of the internal combustion reciprocating engine 1 and the compressor 2 is also of integral construction and it bears the reference 14.

The valves of the compressor 2 are constructed as self-springing non-return valves, the intake valve 15 and the exhaust valve 16 being fixed on the valve plate. The heat evolved inside the cylinder 9 of the internal combustion engine 1 during combustion is partially dissipated by way of the cylinder liner 9, the cylinder head 14, and the exhaust gases flowing through the exhaust valve 4. A heat-exchanger of the internal combustion engine 1 is intended to dissipate the heat evolved during the working process, from the cylinder liner 9 and the cylinder head 14, for which purpose cooling liquid flows through the annular chamber 23 and spaces in the cylinder head 14. To enable the engine exhaust heat to be utilized more satisfactorily, the hot exhaust gas is fed into the annular passage 26 via the exhaust valve 4 and the exhaust-gas duct 25.The annular passage 26 is extensively enclosed by ducts carrying the coolant.

Thus, particularly on entry into the annular passage 26, coolant-carrying ducts are provided on each side, namely: on the right: chamber 23, and on the left: another duct carrying coolant. For more intensive heat transmission from the exhaust gas to the coolant, the wall bounding the chamber 23 has ribs 17 which project into the annular passage 26 acting as an exhaust gas duct, and thus greatly increase the surface. These ribs serve both to guide the exhaust gases and also as a silencer system. The coolantcarrying ducts and the ducts carrying the internal combustion engine exhaust gases form the exhaust gas heat-exchanger. Both the latter and the first heat-exchanger described have the same coolant circuit.

The coolant flows via the coolant inlet 18 in the cylinder head 14 first to the coolant duct 19 and flows through the pressure chamber 20 containing the refrigerant compressed by the compressor 2.

From the liquid duct 19 the coolant flows through at least one duct 21 into the annular chamber 22 surrounding the cylinder liner 10 and then flows downwards. The bottom end of the annular chamber 22 is provided with an aperture leading to the chamber 23. This aperture also discharges into chamber 23 at the bottom end, chamber 23 in turn surrounding the cylinder liner 9. Here the coolant flows upwards and finally reaches the cylinder head, where it particularly cools the hot part in the zone of the exhaust valve 4. Another aperture enables the now relatively hot coolant to flow back into the cylinder block 7 where it cools the hot zone of the annular duct 26 carrying the exhaust gases. The hot coolant then leaves the internal combustion engine 1 through an outlet (not shown in the drawings). The built-in exhaust-gas heat-exchanger in the internal combustion engine consists of the exhaust gas duct 25, which leads from the exhaust valve and into the annular duct 22 at the point farthest away from the compressor 2. As shown in Figs. 2 and 3, the hot exhaust gas flows around the wall which forms the outer boundary of chamber 23 and which bears the ribs 17. To ensure intensive heat transfer, baffles 30 are fixed in the cover 29 so that the hot exhaust gases deliver up heat over a relatively considerable' distance to the coolant in the chamber 23 and in the annular chamber 22. After the now cooled exhaust gases have flowed through the duct 27 surrounding the compressor 2, they leave via the exhaust gas outlet 28, which is disposed in the cylinder block 28 at the point farthest away from the internal combustion engine cylinder.As will be seen from Figs. 2 and 3, the covers 29 are disposed on both sides of the cylinders of the engine 1 and compressor 2 and are fixed by a few bolts to the integral cylinder block consisting of the internal combustion engine cylinder block 7 and the compressor cylinder block 8. The construction of the fairly large aperture through the cover and the easy removal of this cover enable the exhaust gas ducts to be cleaned relatively simply.

Integration of the exhaust-gas heat-exchanger in the internal combustion engine casing or in the internal combustion engine cylinder and cylinder head, is not restricted to a one-cylinder internal combustion engine. A construction of this kind is possible even if the internal combustion engine and the compressor do not form a single structural unit, in which case the engine and the compressor can be interconnected by appropriate connecting passages such as hoses or the like in order to utilize the waste heat. Since the coolant circuit is generally identical with the heating circuit in such heat-pump installations, no additional coolant pump is required at the engine. The circulation in the coolant circuit is produced either by the heating system circulation pump or by gravity.

Claims

1. A heat-pump drive, consisting of an internal combustion reciprocating piston engine connected to a reciprocating piston compressor and heat exchangers are provided to dissipate the heat evolved during the working process and this heat is fed to a heat receiver, at least one heat exchanger being provided inside the reciprocating piston engine, characterised in that an exhaust-gas heatexchanger carrying the internal combustion engine exhaust gases is provided in the engine in addition to the heat-exchanger which cools the engine (cylinder interior cooling by means of coolant in chamber).

2. A heat-pump drive according to claim 1, characterised in that the exhaust-gas heatexchanger is disposed in the cylinder (cylinder block) and/or in the cylinder head.

3. A heat-pump drive according to claims 1 and 2, characterised in that the exhaust-gas heatexchanger is integrated with the heat-exchanger cooling the cylinder and cylinder head of the internal combustion engine and the two heat-exchangers have a common coolant circuit.

4. A heat-pump drive according to claims 1 to 3, characterised in that the exhaust-gas heatexchanger ducts carrying the exhaust gases are surrounded by coolant on all sides.

5. A heat-pump drive according to claims 1 to 3, characterised in that the exhaust-gas ducts are only partially surrounded by coolant.

6. A heat-pump drive according to claims 1 to 5, characterised in that the partition disposed between the exhaust gas ducts and the coolant has ribs projecting into the exhaust gas ducts.

7. A heat-pump drive according to claims 1 to 6, in which the internal combustion engine cylinder block is integral with the compressor cylinder block, characterised in that the exhaust gas heat exchanger and the heat exchanger surround both the internal combustion engine cylinder (cylinder liner) and the compressor cylinder (compressor cylinder liner).

8. A heat-pump drive according to claims 1 to 7, characterised in that the coolant inlet is disposed on the compressor cylinder head and first leads into a liquid duct surrounding the pressure chamber, and at least one duct is provided which leads into the annular chamber surrounding the compressor cylinder (cylinder liner), while said annular chamber is connected to the chamber surrounding the internal combustion engine cylinder and a duct leads from this chamber to the internal combustion engine cylinder head.

9. A heat-pump drive according to claims 1 to 8, characterised in that the exhaust gas ducts comprise annular ducts which surround the coolant chambers surrounding the internal combustion engine cylinder (cylinder liner) and the compressor cylinder (cylinder liner).

10. A heat-pump drive according to claims 1 to 9, characterised in that the exhaust gas duct leading from the exhaust valve leads into the annular duct at the farthest possible point away from the compressor cylinder (cylinder liner), while the exhaust gas outlet is disposed on that side of the compressor cylinder block which is remote from the internal combustion engine cylinder (cylinder liner).

11. A heat-pump drive according to claims 1 to 10, characterised in that the ribs are disposed only partially on the periphery of the partition and baffle means for the exhaust gases are provided between the cylinders (cylinder liners) in that zone is devoid of ribs.

12. A heat-pump drive according to claims 1 to 11, characterised in that the exhaust gas ducts disposed in the cylinder block (internal combustion engine cylinder block and compressor cylinder block) are bounded on the outside by covers fixed to the cylinder block.

13. A heat-pump drive according to claims 1 to 12, characterised in that the baffle means are disposed on the covers.