US2338931A

US2338931A - Refrigerating apparatus

Info

Publication number: US2338931A
Application number: US358873A
Authority: US
Inventors: Richard E Gould; Charles F Henney
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1940-09-28
Filing date: 1940-09-28
Publication date: 1944-01-11
Anticipated expiration: 1961-01-11

Description

Jan. 11, 1944.

R. E. GOULD ETAL REFRIGERATING APPARATUS Filed Sept. 28, 1940 3 Sheets-Sheet l om om *n om 3 INVENORa AoRNEY Jan. ll, 1944. R. E, GoULD ETAL REFRIGERATING APPARATUS Filed Sept. 28, 1940 3 Sheets-Sheet 2 8 l INVENTOR@ ------,.ilwdlJ .1 P 1TEK Imm l munlullllllllnmlll- ATTORNEYS Jan* 119 R. El. GOULD ETAL REFRIGERATING APPARATUS INVENTORS M Bw W M ATTORNEY:

Patented Jan.v 11, 1944 REFRIGERATING APPARATUS Richard E. Gould and Charles F. Henney, Dayton, Ohio, assignors to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application September Z8, 1940, Serial No. 358,873

3 Claims.

This invention relates to refrigerating apparatus and more particularly to refrigerating apparatus adapted to condition the air for the passenger compartment of a vehicle or the like.

One object of this invention is to provide an improved refrigerant liquefying unit in which the compressor may be directly driven from an internal combustion engine.

Still another object of this invention is to provide an improved shaft seal arrangement for use with a high speed compressor.

A further object of this invention is to provide an improved arrangement for cooling the shaft seal by means of liquid refrigerant.

A still further object of this invention is to provide means for recondensing refrigerant which may have been evaporated in cooling the shaft seal.

Another object of this invention is to provide an improved control circuit for use in the above mentioned refrigerating system.

It is also an object of this invention to improve upon the general arrangement of parts in a refrigerating system of the type adapted to be mounted on a vehicle.

Another object of this invention is to provide an improved means for unloading the compressor so as to facilitate cranking of the compressor engine.

Still another object of this invention is to utilize one chamber of a heat interchanger as an unloading chamber.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. l is an elevational view with parts broken away showing the arrangement of the elements on a bus;

Fig. 2 is a top view showing the general arrangement of the refrigerant liquefying unit;

Fig. 3 is a fragmentary sectional view taken on the line 3-3 of Fig. 2, showing diagrammatically the refrigerant fiow circuit; and

Fig. 4 is a diagrammatic view showing the electrical controls for the refrigerating apparatus.

In designing air conditioning apparatus for use on a bus or the like, it is important to conserve on space and weight and at the same time, it is also important to provide refrigerant liquefying apparatus, which requires a minimum amount of servicing from time to time. It is also important to design the refrigerating apparatus so side wall of the bus.

that the refrigerant liquefying mechanism may be disconnected from the refrigerant evaporator without disturbing the supply of refrigerant in the system and without contaminating the interior of the refrigerant flow path.

In Fig. l, of the drawings, we have shown a preferred embodiment of our invention in which the reference numeral it is used to designate a conventional passenger bus having a main passenger compartment ii. An air duct I2 is provided beneath the floor of the passenger compartment and communicates with the passenger compartment it through return air passages iii provided in the oor of the passenger compartment il. The air to be conditioned is circulated through the duct i2 by :means of a blower unit i6 mounted Within an enlarged portion of the duct i2. The blower unit i6 withdraws air from 'the passenger compartment ii through the openings i4 and discharges the air into a vertical duct i8 which communicates with a horizontally disposed air duct t0 mounted directly above the normal head room of the bus. The duct 20 is provided with louvers such as 22 for directing air into the main passenger compartment and louvers 24 for directing air into the drivers compartment located at the front of the bus. While only one set of air ducts i8 and 2U can be seen in Fig. 1, it is to be understood that a similar set is provided on the other side of the bus whereby the conditioned air discharges into the passenger compartment from both sides of the bus. The desired amount of fresh air may be introduced into the duct l2, through the fresh air grille 26 provided in the The mixture of fresh air and recirculated air is caused to fiow through an air lter 28 and a refrigerant evaporator 30 also located in the enlarged portion of the air duct l2.

Liquid refrigerant is supplied to the evaporator 3G by the refrigerant liquefying apparatus mounted beneath the air duct I2. The refrigerant liquefying apparatus comprises an internal combustion engine 34 which is direct connected to a rotary compressor unit 36. The internal combustion engine 36 also drives a fan 38 which circulates air in through the inlet 52 and out through the outlet 4D. The internal combustion engine 34 and its associated elements are mounted on a frame E4 which also supports the engine radiator 46 and the refrigerant condenser d8. The frame '36 is removably and resiliently mounted on the bus by means of a plurality of rubberlike mounting's.

Referring now to Fig. 3 in which the refrigerant ow circuit is diagrammatically shown, it is apparent that the compressed refrigerant leaving the compressor 38 via the line 52, first enters the condenser 48 in which the compressed refrigerant vapor is converted into liquid refrigerant. The liquid refrigerant leaves the condenser 48 through the line 5B. 'I'he liquid refrigerant flowing in line 56 discharges into a shaft seal cooling chamber 58 through the opening 18 located adjacent the bottom of the chamber 88. As shown in Fig. '3, the compressor 38 comprises a conventional rotary compressor unit 88 which discharges the compressed refrigerant at 82 into the chamber 84 formed`by the outer shell 85. The compressor operating shaft 88 which is an extension of the engine shaft, is supported in a Inasmuch as the compressor is direct connected to the internal combustion engine, it is desirable to provide means for unloading the compressor after each shut-down so as to avoid having to crank the engine when the compressor is under load. For this purpose, I have provided asmall capacity by-pass line 88 between the compressor discharge line 82 and the outer chamber of the heat interchanger 84. The bypass line 98 is in the form of a very small tube whereby the quantity of refrigerant by-passed through the line 98 does not materially reduce the capacity of the refrigerant system while the compressor is in operation. The small capacity bearingelement 88 secured to the casting 78 by means of bolts 1|. The member 18, in turn, is bolted to the engine housing by means of bolts 12.

In order to simplify this disclosure, the details of the gaskets whichare used for sealing the joints between the main compressor casing 88 and the elements 88 and i8 have been omitted. It is to be understood, however, that the joints between these elements are refrigerant tight. In order to prevent the escape of refrigerant along the shaft 68, a conventional shaft seal unit 'I8 has been provided. Inasmuch as shaft seals of this general type are old and insasmucli as the specific details of the shaft seal are immaterial. the details of the shaft seal structure have not been shown.

Inasmuch as shaft seals of all types will generate a certain amount of heat especially at high shaft speeds and inasmuch as it is desirable to provide a direct connection between the engine and the compressor and to operate the compressor at high speeds, it is important to provide some unfailing means for cooling the shaft seal 14. In order to cool the shaft seal 14 all of the liquid refrigerant leaving the condenser 58 is caused to flow directlyinto the chamber 58 surrounding the main compressor bearing and the shaft seal mechanism 74. The liquid refrigerant discharges into the cavity 58 at the point 18 and leaves the cavity at 88. inasmuch as the heat generated is at times sufficient to vaporize a portion of the liouid refrigerant flowing through the cavity 58, the refrigerant leaving the cavity 58 is circulated through the inner section 82 of a heat interchanger 84 which also functions as a receiver for the condensed liquid refrigerant.

The liquid refrigerant leaving 82 flows through a conventional fixed restrictor 88 before entering the evaporator 38. 'I'he fixed restrictor 88 may be any one of several well known types, such as a long length of small diameter capillary tubing or it may be of the type disclosed in Patent No. 2,863,745. A check valve 88 is provided at the outlet of the evaporator so as to prevent the reverse flow of the refrigerant back into the evaporator. The refrigerant vapor leaving the evaporator 38 is at a relatively low temperature andis passed through the heat interchanger 84 wherein it serves to cool the refrigerant flowing through the inner portion 82 of the heat interchanger. Any refrigerant which may have been evaporated in the chamber 58 is recondensed in the interchanger. The refrigerant vapor coming from the evaporator 38 flows from the heat interchanger 84, through pipes 98, check valve 92 and thence the inlet S4 of the pump 88. The check valve 92 prevents any of the lubricant 93 from backing up into the interchanger 84 during the off cycle.

lay-pass4 does, however, serve to equalize the pressure between the compressor outlet line 82 and the heat interchanger 84 in a relatively short period of time during any period of shut-down. By virtue of the' check valve 88, the equalization of pressure between the high side of the compressor and the low side of the' compressor is limited to only a small` portion Vof the refrigerant circuit. y

Referring now to Fig. 4, in which the electrical control circuit is shown, the reference numeral |88 designates a storage battery which may be kept charged by the bus generator in the usual well known manner. Reference numeral |82 designates a'manual switch which serves to turn on and oil? the entire air conditioning system. Reference numeral |84 designates a manual switch provided in the blower motor circuit. Upon closing of theswitches |82 and |84, the blower motor I6 is energized and will continue to circulate air within the bus so long as the switches remain closed. Reference numeral |88 designates a manual switch which controls the main thermostats ||8 and ||2 which in turn control the operation of the'internal combustion engine 34. Closing of the switches 82 and |88 also energizes a signal light. |88 which may, for

. example, be mounted in the drivers compartment. Whenever the light' |88 is lit this indicates that the switches |82 and |88 are both closed. The thermostat |8 is set to operate at a higher temperature than the thermostat l2. The thermostat 8 controls the circuit to solenoid coil H4 which when energized serves toincrease the speed of the engine by opening the engine throttle so as to increase the capacity of the refrigerating system. The low temperature thermostat 2 is in'series with the engine ignition coil I8. The thermostats ||8 and ||2 are preferably placed within the passenger compartment or in the return air stream. Upon closing of the thermostat ||2, the ignition coil ||8 is energized. In order to start theV engine, however, it is necessary for the operator to manually close the normally open starter push button ||8 which is arranged in series with the solenoid coil |28'. Energization of the coil |28 closes the switch |22 which is arranged in circuit with the conventional engine starter motor |24. The starter motor |24 serves to crank the vengine 84 in the usual well known manner. as the engine 34 starts, 'the push button ||8 is releasedl so as to open the circuit tothe starter motor at |22. As the engine 84 gains speed this automatically causes opening of the switch |28 arranged in series with the indicator light |28.

.'Ihe switch |26 may be of the type in which the air circulated by the engine fan 88 strikes a wind vane |21 carried by the switch |28 thereby opening the switch.

By virtue of the above arrangement, whenever Just as soon cuit to coil lll whereby the speed of the engine will be reduced. If operation of the engine 34 at the reduced speed provides more than the necessary amount of refrigeration, the temperature within the passenger compartment will finally drop below the value at which the thermostat ||2 is set, whereby the circuit to the ignition coil IB will be opened and the engine will be stopped. After each period of shut-down the thermostat ||2 is the first to close, but inasmuch as it is not practical to crank the engine at too frequent intervals the operator does not restart the engine until the thermostat ||0 is also closed at which I time the signal lamp |28 gives the operator notice that the temperature in the passenger compartment is above the desired value and that the engine should be started. It is possible, however, for the operator to restart the engine, if desired, any time after the thermostat ||Z has closed. If the engine is started before thermostat ||0 is closed the engine will operate at the reduced speed since the coil ||I will not be energized under such conditions.

While I have disclosed two separate thermostats no and nz, it is within the purview or this invention to use, a single thermostat which closes a first circuit to the ignition coil at one temperature andwhich closes a second circuit to the throttle control coil ||4 at a slightly higher temperature. In order to simplify this disclosure we have shown switches |02, |04, |06 and ||8 as manually operated switches whereas these switches may be operated in response to the temperature'or humidity of either the outside air or the inside air.

In a refrigerating system of the type adapted to be installed on a bus, it is frequently desirable to remove the engine and the compressor unit from the bus for inspection and repair purposes. In order to facilitate the removal of the engine and the compressor unit from the bus without disturbing the refrigerant charge in the refrigerant circuit, a special separable connector |60 is provided, as' shown in Fig. 2. The connector |50 includes a first dual valve housing |50 which carries 'a pair of manually operable valves |52 and a second dual valve housing |58 which carries a pair of manually operable valves |54. The

housings |55 and |58 are normally held together by the bolts |50. The valves are normally open at all times when the refrigerating system is in operation but are adapted to be closed when it is desired to disconnect the evaporator from the rest of the system so as to lmake it possible to remove the rest ofthe system from the bus. The arrangement is such that the condenser 48, which is supported on the main frame 44 is removed along with the engine 34 and compressor l0. BY closing the valves |52 and |54, the refrigerant connections between the evaporator and the rest of the system may be disconnected without disturbina the refrigerant and lubricant charge within the system and without introducing any inert gas or moisture into the refrigerant circuit.

It is common practice in the refrigeration art to provide a drier cartridge somewhere in the -refrigerant circuit for absorbing any water which may be found in the refrigerant system. Cartridges of this type are well known in the art and usually comprise a body of anhydrous calcum sulphate. These cartridges are of necessity small and can absorb only a limited amount of moisture. I have placed a removable cartridge |60 of this type between the two sections |56 and |58 of the connector |50 whereby upon disconnecting the refrigerant circuit at |50, the cartridge |60 becomes accessible and may be reactivated or replaced so that upon reconnecting the refrigerant system a new cartridge may be inserted which is capable of removing any moisture which may have found its way into the refrigerant circuit.

By virtue of the above described arrangement, the refrigerant liquefying apparatus may be disconnected from' the evaporator any number of times without disturbing the refrigerant charge and without destroying the effectiveness of the drying cartridge.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows: l. In combination, a compressor including a drive shaft, a shaft seal therefor and a shaft seal cooling cavity, a condenser, an evaporator, a heat interchanger including a rst passage and a second passage, refrigerant flow connections for directing the compressed refrigerant leaving the compressor through the condenser, the shaft seal cooling cavity, the rst passage of the heat interchanger, the evaporator, the second passage of the heat interchanger and thereafter into the inlet of the compressor, means preventing reverse flow 'of refrigerant from the second passage of said interchanger to said evaporator, and means for unloading said compressor including means for equalizing the pressure between the second passage of said heat interchanger and the outlet of said compressor.

2. In combination, a compressor including a drive shaft, a shaft seal therefor and a shaft seal cooling cavity, a condenser, an evaporator, a heat interchanger including a first passage and a second passage, and refrigerant ilow connections for directing the compressed refrigerant leaving the compressor through the condenser, the shaft seal cooling cavity, the first passage of the heat interchanger, the evaporator, the second passage of the heat interchanger and thereafter into the inlet of the compressor.

3.f In combination, a compressor including a drive shaft and a shaft seal therefor, a condenser, an evaporator, refrigerant flow connections between said compressor, condenser and evaporator, said refrigerant ow connections including means for conducting liquid refrigerant from said condenser into thermal exchange with'said shaft seal and thereafter into thermal exchange with refrigerant vapor flowing from said evaporator to the inlet of said compressor.

CHARLES F. HENNEY. RICHARD E. GOULD.