GB2503516A

GB2503516A - A refrigeration compressor for a vehicles HVAC device with a water cooling jacket connected to the vehicles engine coolant circuit.

Info

Publication number: GB2503516A
Application number: GB1211771.9A
Authority: GB
Inventors: Venkat Rao Gangumalla
Original assignee: Daimler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2012-06-25
Filing date: 2012-06-25
Publication date: 2014-01-01
Also published as: GB201211771D0

Abstract

A refrigeration compressor 5 for a vehicle HVAC device comprises a compressor body surrounded by a cooling jacket (fig 2a, 6) with inlet 7 and outlet 8 connectors, the jacket having a rectangular cross section. The compressor forms part of a refrigerant circuit with a condenser 1, an expansion valve 11 and an evaporator 2. The jacket connects to the engine coolant circuit 9 comprising, a charge air cooler 4, a low temperature radiator 3, a pump 6 and downstream of the pump a junction 10 where the jacket inlet is connected and another junction 10 between the radiator and the charge air cooler where the jacket outlet connects. The coolant used may be water.

Description

I

Daimler AG Automotive HVAC device The invention relates to an automotive HVAC refrigeration device with refrigeration compressor having an external cooling system.

It is generally known in the state of the art, that an automotive HVAC (heating, ventilation and air conditioning) system consists of four major components that are compressor, condenser, expansion device and evaporator. The refrigeration system thermal efficiency (COP) depends upon various parameters including the mechanical energy consumed by compressor for compression process.

As per the existing design concepts, the refrigerant compressor is usually located in the engine compartment and therein exposed to high local ambient temperatures also during the compression process. Hence, the compressor temperatures will rise. These high operating temperatures may therefore increase compression work and will in the following affect compressor lifetime and reliability.

A refrigeration compressor with internal cooling system also is known from US 2011/0154982 Al. It comprises piston drive means, which drive the alternating movement of the piston inside the cylinder, and which comprise a motor and a stator which drive a rotary shaft. The lower end of the shaft is immersed in the oil well, whereas its opposite upper end is mounted to a cam which drives the piston movement. This compressor also has a pumping system which pumps the oil upwards that is accumulated in the oil accumulation region, towards the piston drive means, and particularly around the rotary shaft, when the compressor is switched on, such that a portion of the oil is expelled upwards, towards the upper face inside the compressor shell, or on the cover of the compressor: and also sideward, over the inner walls of the upper region of the compressor shell. Another portion of oil expelled by the cam around the area formed between the compressor block and the upper face of the shell falls again and runs over the compressor block as a whole. Said oil flows provide cooling.

Further WO 20071068072 is directed at cooling a compressor cylinder by being isolated from heating sources. The heat transmission from valve plate to cylinder cover is therefore reduced. Thus the compression process takes place at relatively lower temperatures and results in lower compressor power consumption.

Wa 2007/014443 refers to a hermetic refrigerant compressor which uses heat tubes to remove heat from hot parts which are in contact with the cylinder. Heat tubes dissipate heat from the cylinder to ambience and thus reduce compression temperatures.

US 4569639 describes a refrigeration compressor which uses existing compressor lubrication oil to cool the compressor cylinder to reduce compression temperature.

Based on this state of the art, it is an object of the invention to provide an improved cooled refrigeration compressor which is applicable to an automotive HVAC refrigeration device and which can be produced economically.

This object is solved by the refrigeration compressor having the features according to claim 1.

The further object to provide an improved automotive ft/AC-device is solved by the device with the features of claim 3.

Preferred embodiments of the devices method are shown by the dependent claims.

According to a first embodiment of the present invention, the refrigeration compressor of the invention is adapted to be arranged in an automotive HVAC refrigeration device, and comprises a compressor body which is at least partly surrounded by a cooling jacket. The cooling jacket is provided with at least one coolant inlet connector being designed to permit coupling of said cooling jacket with a coolant supply and with at least one coolant exit connector being designed to permit coupling of said cooling jacket with a coolant discharge. So said refrigeration compressor is advantageously provided with an outer cooling which enables operating the compressor at relatively low temperatures, thus improving its lifetime.

An appropriate geometry of the cooling jacket which surrounds most of the body of the compressor can be a rectangular cross-sectional shape.

According to embodiments of the invention said compressor can be integrated in an automotive HVAC refrigeration device comprising -a refrigeration compressor, -a charge air cooler, a low temperature radiator and downstream the charge air cooler, a pump, said devices being connected and forming a first coolant circuit, -a refrigerant circuit comprising a condenser, an expansion valve, an evaporator and said refrigeration compressor which is connected to said first coolant circuit via the coolant inlet connector and the coolant exit connector forming a second coolant circuit. So, efficiency of the device is optimized using the existing first coolant circuit to cool the compressor, which makes the whole system more efficient and reliable and can be easily realized.

The junctions for designing the second coolant circuit can be a junction downstream pump, being connected to the coolant inlet via tubes or hoses or the like, and another junction being sited between the charge air cooler and the low temperature radiator, providing the fluidic connection to said coolant exit connector; The coolant used herein may be water.

Other objects and many of the attendant advantages of embodiments of the present invention will be readily appreciated and become better understood by reference to the following more detailed description of preferred embodiments in connection with the accompanied drawings. Features that are substantially or functionally equal or similar will be referred to with the same reference signs. The figures show: Fig. 1 working principle of an HVAC-device according to the invention, Fig. 2a side view of a refrigerant compressor, Fig. 2b front cross sectional view of the refrigerant compressor according to Fig. 2a.

The herein disclosed invention refers to an automotive HVAC comprising a compressor, condenser, expansion device and an evaporator. Embodiments of said invention allow reducing of the compressor operating temperature, therefore resulting in lower compression work and an improved compressor lifetime and reliability.

An isothermal compression process is, with respect to thermodynamics principles, regarded as an ideal process. Said process is used for the herein depicted new operating system, and makes use of the concept to cool the refrigeration system compressor using a cooling medium that passes around the compressor's outer surface.

Such compressor 5 is shown in Fig. 2a, and 2b. In order to realize the improved heat dissipation it has a coolant jacket 6 for the compressor 5 around most of the outer surface of the compressor body 5' of said compressor. In order to provide an appropriate flow path for coolant or cooling fluid, respectively, said coolant jacket 6 is provided with a coolant inlet and coolant exit connector 7,6; so the coolant jacket 6 is integrated into the coolant fluid path 7',8' shown in Fig. 1 via said connectors 7,8, to permit coolant fluid passage.

Of course, in other embodiments additional coolant inlet and exit connections could be provided.

Generally, the cooling jacket 6 around the compressor is designed to enable an improved flow and heat transfer performance. The cooling jacket 6 as shown in Fig. 2a,2b is therefore only a simple embodiment depicting the function of said jacket 6 and could be designed far more sophisticated. Herein -being an example only -a rectangular flow channel forms the jacket 6 for coolant flow and is kept around the compressor body 5'.

The new proposed system or I-WAG-device, respectively, offers an improved refrigeration system performance due to allowing the compressor 5 to operate at relatively low temperature and thus to reduce compressor power consumption, leading to an improved efficiency (coefficient of performance) of the refrigeration circuit.

The coolant is supplied from the low temperature circuit 9, see Fig. 1, and is used for the cooling refrigerant compressor 5 in that at least a portion of it is guided through said cooling jacket 6 (not depicted in Fig. 1) to remove heat from the compressor 5.

Since this system utilizes the existing low temperature circuit 9 as a coolant source, it does not need additional components. As the compressor gets externally cooled, the refrigerant inside the compressor 5 will release heat to the cooling medium, therefore optimizing the compression process which approximates an isothermal process.

Upstream compressor 5, the coolant fluid path is referenced with 7'; downstream compressor 5, the coolant fluid path is referenced with 6'.

Further, the refrigerant at the compressor 5 exit maintains high pressure and relatively low temperature. Advantageously this results into reduced compressor power consumption and further in needing a reduced size of the condenser 1.

In order to accommodate this additional heat load due to the increased heat load of the low temperature circuit 9, it is suggested to increase the size of the low temperature radiator 3 (with respect to former comparable conventional refrigerator compressor system radiator sizes). Said disadvantage of the increased low temperature radiator size will be compensated by the reduced condenser size.

The working principle of the proposed system is as follows: An existing vehicle refrigeration system compressor Swill be cooled by a coolant, preferably water, which is supplied with a relatively low temperature from the existing vehicle low temperature circuit 9, which further comprises a charge air cooler 4, as known by the technically skilled person. Said existing low temperature coolant circuit 9 is split at junction 10 downstream a pump 6, which is located in the refrigerant flow path 9' downstream the low temperature radiator 3, providing some refrigerant to the compressor via a tube/hose connection.

The coolant passes through the compressor cooling jacket 6 as shown in Figs 2a,2b, taking up heat from the compressor 5. The warmed up coolant is reverted into the low temperature circuit 9 upstream the low temperature radiator 3 at a second junction 10'; again using a hose/tube connection.

Thus the refrigerant compressor 5 is cooled and kept at low temperatures. As can be seen, the compressors is part of a refrigerant circuit as known in the state of the art, comprising a condenser 1. an expansion valve 11 and an evaporator 2.

Furthermore, the refrigeration compressor 5 according to an embodiment of the invention may additionally have an internal cooling system as known in the state of the art, e.g., the one described in US 4569639 or US 2011/0154982 Al, which use existing compressor lubrication oil to cool the compressor cylinder to further reduce compression temperature.

Claims

Claims Refrigeration compressor (5), adapted to be arranged in an automotive HVAC refrigeration device, characterized in that said refrigeration compressor (5) comprises a compressor body (5') which is at least partly surrounded by a cooling jacket (6), said coaling jacket (6) being provided with at least one coolant inlet connector (7), which is designed to permit coupling of said cooling jacket (6) with a coolant supply, and at least one coolant exit connector (8) designed to permit coupling of said cooling jacket (6) with a coolant discharge.
2. Refrigeration compressor (5) according to claim 1, characterized in that said cooling jacket (6) has a rectangular cross-sectional shape.
3. Automotive HVAC refrigeration device comprising -a refrigeration compressor (5), -a radiator (3) and -a pump (6), characterized in that said devices being connect!d and forming a coolant circuit (7', 8'), and -a refrigerant circuit comprising a condenser (1), an expansion valve (11),an evaporator (2) and said refrigeration compressor (5), the refrigeration compressor (5) is the refrigeration compressor (5) according to one of claims 1 or 2, wherein said refrigeration compressor (5) is connected via the coolant inlet connector (7) and the coolant exit connector (8) to said coolant circuit (7', 8').
4. Automotive HVAC refrigeration device comprising -a refrigeration compressor (5), -a charge air cooler (4), a low temperature radiator (3) and downstream the charge air cooler (4) a pump (6), said devices being connected and forming a first coolant circuit (9), -a refrigerant circuit comprising a condenser (1), an expansion valve (11),an evaporator (2) and said refrigeration compressor (5), characterized in that the refrigeration compressor (5) is the refrigeration compressor (5) according to one of claims 1 or 2, and wherein said refrigeration compressor (5) is connected via the coolant inlet connector (7) and thecoolant exit connector (8) to said first coolant circuit (9), forming a second coolant circuit (7,8').
5. Device according to claim 3 or 4, characterized in that the first coolant circuit (9) comprises a junction (10) downstream pump (6), and wherein the coolant inlet (7) is connected to said junction (10), and wherein between the charge air cooler (4) and the low temperature radiator (3) another junction (10') is provided, providing the fluidic connection to said coolant exit connector (8).
6. Device according to one of the claims 3 to 5, characterized in that the coolant possesses a essential fraction of water.