US2916880A

US2916880A - Drive for refrigeration systems or the like

Info

Publication number: US2916880A
Application number: US612766A
Authority: US
Inventors: Melvin M Hann
Original assignee: Sundstrand Corp
Current assignee: Sundstrand Corp
Priority date: 1956-09-28
Filing date: 1956-09-28
Publication date: 1959-12-15
Anticipated expiration: 1976-12-15

Description

Dec. 15, 1959 M. M. HANN 2,91

DRIVE FOR REFRIGERATION SYSTEMS OR THE LIKE Filed Sept. 28, 1956 545cm MOTOR ENG/NE z? 19 CONOE/V6'0R ENS/NE INVENTOR.

MW 772 HW 5y BYXM f?"'""" United States Patent DRIVE FOR REFRIGERATION SYSTEMS OR THE LIKE Melvin M. Hann, Rockford, Ill., assignor to Sundstrand Corporation, a corporation of Illinois Application September 28, 1956, Serial No. 612,766

1 Claim. (Cl. 6053) This invention relates to drives for refrigeration systems or the like and to controls for such drives.

It is a general object of the invention to provide a new and improved drive of the character described and to provide new and improved controls therefor.

A more specific object is to provide a new and improved drive for refrigeration systems or the like including a hydraulic pump for supplying fluid under pressure to drive one or more of a plurality of hydraulic motors, and auxiliary means for driving one of the plurality of hydraulic motors mechanically when the pump is inoperative so that the motor functions as a pump for supplying fluid under pressure to drive the other of the hydraulic motors.

It is also an object of the present invention to provide, in a drive for refrigeration systems of tractor-trailer units wherein the pump is driven by the tractor engine, new and improved controls including means responsive to a pump load condition for controlling the tractor engine idle speed so as to maintain thev idle speed when a load is imposed on the engine to thereby avoid stalling the engine.

Other objects and advantages will become readily apparent from the following detailed description taken in connection with the accompanying drawings, in which:

Fig. l is a diagrammatic showing of a refrigeration drive and control therefor embodying the principles of the present invention;

Fig. 2 is a diagrammatic showing of a fragmentary portion of the drive illustrated in Fig. 1, showing certain of the parts in a second position;

Fig. 3 is a diagrammatic showing of a fragmentary portion of the drive illustrated in Fig. 1, showing a modification of a control for the drive; and

Fig. 4 is a diagrammatic showing of the drive and control illustrated in Fig. 3, showing certain of the parts in a second position.

While illustrative embodiments of the invention are shown in the drawings and will be described in detail herein, the invention is susceptible of embodiment in many different forms and it should be understood that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiments illustrated. The scope of the invention will be pointed out in the appended claim.

This invention constitutes an improvement over the drive of my copending application, filed September 19, 1955, as application Serial No. 535,146.

The drive of the present invention is particularly adapted for refrigeration systems of tractor-trailer units or the like. Such systems may be comprised of a number of separate or combined components including a compressor 10, a condenser 11 having

fans

12 and 13, and a remotely located evaporator 14 having a fan 15.

Drives of the character described may advantageously be driven normally from the prime mover for the tractor, such as the engine 17, and as illustrated, include a ice hydraulic motor 18 for driving the

condenser fans

12 and 13 and for driving the compressor 10, and a hydraulic motor 19 for driving the evaporator fan 15. The condenser fan 12 is secured on the shaft 20 of the hydraulic motor 18, and the shaft 20 is provided with a pulley 21 connected by a belt 22 to a pulley 23 on the shaft of the compressor 10 to drive the compressor. The condenser fan 13 is secured to the shaft of the compressor.

When the tractor engine is not in operation, which may occur under a number of conditions, the compressor, and condenser and evaporator fans, may be driven by means of an auxiliary A.C. electric motor 25 having on its drive shaft a pulley 26 connected by belt 27 to a pulley 28 on the shaft 20 of the hydraulic motor 18, all as described more in detail hereinafter.

Normally, however,

motors

18 and 19 are driven by means of fluid under pressure supplied from a hydraulic pump 29 connected to be .driven by the tractor engine 17. Fluid is supplied to the hydraulic pump 29 from a reservoir 30 connected by a line 31 to the pump intake. The pump discharge is connected by a line 32 to the inlet for the hydraulic motor 18. The outlet from hydraulic motor 18 is connected by a line 33 to the inlet for the hydraulic motor 19. The pump discharge and the

hydraulic motors

18 and 19 are thereby connected in series. The outlet from hydraulic motor 19 is connected with a conduit 34 for returning fluid to the reservoir 30. Leakage fluid from the casing of the pump 29 and from the casing of the hydraulic motor 18 may be conducted in a conventional manner through leakage lines (not shown) leading to the reservoir 30.

With the system as described thus far, it will be seen.

that on operation of the tractor engine 17, the pump 29 will thereby be driven to supply fluid under pressure for driving the

hydraulic motors

18 and 19, with return fluid from the motor 19 being conducted to the reservoir 30. The

condenser fans

12 and 13, the compressor 10 and the evaporator fan 15 are thereby driven to operate the entire refrigeration system. During operation of the hydraulic motor 18, when its shaft 20, the pulley 28, the belt 27, and the pulley 26, are all driven, the electric motor 25 free wheels.

Obviously, the speed of the tractor engine 17 may vary during its operation, and variations in speed of the engine are effective to vary the displacement of the pump 29. If desired, the pump may include controls of the character described in my copending application referred to above to provide a constant supply of fluid to the hydraulic motor 18 and the hydraulic motor 19 in order that these motors will be operated at a constant speed. Additionally, if desired, the pump 29 may be provided with a solenoid controlled valve generally designated 39, of the character described in my aforesaid copending application, for feathering or disabling the pump 29 so thateven though the tractor engine and pump are driven, no fluid is delivered for operating the

motors

18 and 19. In this manner the refrigeration equipment including the condenser fans, the compressor, and the evaporator fans may be disabled during the operation of the tractor engine 17. The hydraulic pump 29 and the hydraulic motor 19 may, if desired, be of a construction described more in detail in my aforesaid copending application.

Under some conditions, it may be desirable to operate the evaporator fan 15 separately, that is, without operating the

condenser fans

12 and 13 or the compressor 10.

valve 41 may be opened so that fluid under pressure delivered to the line 32 passes through the conduit 40 and to the conduit 33. Fluid under the same pressure is thereby delivered to both the inlet and the outlet for the motor 18 and the motor is thus not operated. However, fluid under pressure flows to the inlet for the motor 19 and this motor is operative to drive the evaporator fan 15.

As previously indicated, it may be desirable to operate the refrigeration system at a time when the tractor-engine is not operating. Such an event may occur, for example, when the tractor-trailer unit is at a standstill or garaged for an overnight period. It is for this purpose that the electric motor 25 is provided. The motor 25 may be supplied with power through leads such as those illustrated at 44 from an outlet convenient to the place where the tractor-trailer is garaged.

As previously described, when the hydraulic motor 18 is driven by fluid under pressure from the pump 29, the motor 25 free wheels. However, when the motor 25 is driven, the hydraulic motor 18 does not free wheel. Instead, the motor 18 may be of a conventional construction such that it functions as a pump when driven by the electric motor 25. In this case, the

condenser fans

12 and 13 and the compressor are driven by the electric motor 25. Also, the hydraulic motor 18 functions as a pump, drawing fluid in through the conduit 32 and supplying fluid under pressure to drive the hydraulic motor 19.

During operation as described immediately above, it is undesirable that fluid be drawn through the pump 29 to the hydraulic motor 18 which is then functioning as a pump. Accordingly, the hydraulic system includes a conduit 46 connected with the conduit 31 leading from the reservoir to the pump 29 and also connected with the conduit 32 leading to the hydraulic motor 18. The conduit 46 is provided with a blocking valve 47Which may be normally closed to prevent flow of fluid through the conduit 46. Upon energization of the electric motor 25, the valve 47 may be opened to bypass the pump 29 and to connect the reservoir 30 directly to the inlet to the motor 18.

The blocking valves 41 and 47 may, if desired, be of the construction described in detail in the copending joint application of myself and Harry C. Moon, Jr., filed December 30, 1955, as Serial No. 556,540. As described in the joint application referred to, such valves may be solenoid operated, and are thus conveniently adapted for use in the hydraulic circuits described herein.

When the tractor-trailer unit is in operation, and the load of the refrigeration drive described may thereby be imposed on the tractor engine, but at a time when the tractor engine is idling, the load of the refrigeration drive may be sufiicient to stall the tractor engine. Obviously, this is an undesirable condition. Accordingly, the present invention encompasses the provision of control means to prevent stalling the engine by maintaining the engine idle speed when a load is imposed on the hydraulic pump 29. The function of such control means is to maintain the engine idle speed substantially constant, regardless of the load imposed thereon by the pump 29. For example, if the engine normally idles at about 500 r.p.m. when no load is imposed, it is desired that this speed be maintained when a load is imposed.

Referring to Fig. l, the tractor engine is provided with carburetion apparatus generally designated 50 including a carburetor having a supply line 51 and adapted to control the supply of fuel to the truck engine through a line 52 so as to control the speed of the engine. Mechanical linkage is provided for controlling the carburetor and includes an elongated rod 53 suitably connected with a foot operable pedal 54. A spring 55 is provided to bias the carburetor linkage and the foot pedal 54 toward a normal position determined by adjustable stop screw 55' at which the engine 17 idles normally when no load is imposed thereon by the pump 29. In order to avoid stalling the engine 17 when a load is imposed on the pump 29, the rod 53 associated with the carburetor linkage is provided with an abutment member 56 engageable with a movably mounted stop 57 which is controlled in response to the discharge pressure from pump 29.

As illustrated in Figs. 1 and 2, the stop 57 comprises a piston rod connected with a piston 58 reciprocable in a cylinder 59. A spring 60 acts against one end of the cylinder and against one side of the piston to normally bias the stop 57 to a position which permits return of the carburetor linkage to its normal idle position. The opposite end of the cylinder 59 is connected by a conduit 32a to a line 32 which delivers the high pressure pump discharge. In this manner, when the pump 29 is delivering at a high pressure discharge and a load is thus imposed on the tractor engine 17, the pressure of fluid in the

conduits

32 and 32a will be sufiicient to move the piston 58 and stop 57, against the bias of the spring 60, to a position which prevents return movement of the carburetor linkage to a normal engine idle position and instead limits movement of the carburetor linkage under the urge of spring 55 to an idle position with power sufiicient to maintain operation of the tractor engine 17 at a speed such that the engine will not be stalled by the load imposed thereon. Movement of the piston 58 and stop 57 in a power idle direction may be limited by a stop sleeve 59 fixed in the cylinder 59 and engageable by the piston 58. Fig. 1 illustrates the stop 57 and the carburetor linkage in the so-called power engine idle position, while Fig. 2 illustrates these parts in a normal idle position.

Referring now to Figs. 3 and 4, l have illustrated a modification of a control for preventing stalling of the engine 17 when idling and when a load may be imposed thereon by the pump 29. As seen in these figures, the control includes a stop 61 which constitutes the rod of a piston 61' normally biased by a spring 62 to a position wherein the stop 61 engages abutment member 56 to maintain the carburetor linkage in a power idle position. Movement of the stop 61 in power idle direction may be limited by a stop sleeve 62 fixed in the cylinder which houses the piston 61'. The stop 61 comprises the core of a solenoid having a winding 63 which, when energized, is effective to move the stop to a position which frees the carburetor linkage for return movement under the urge of spring 55 to a normal engine idle position defined by stop screw 55.

The solenoid valve 39 for feathering or disabling the pump 29 includes a winding 64 which when energized is elfective to feather the pump. The winding 64 is connected to ground at 65 and is connected by means of a wire 66 to a source of power such as a battery 67, which may, if desired, be the tractor battery normally provided for purposes such as starting. A normally open switch 68 connected in circuit with the winding 64 and with the battery 67 may be closed to effect energization of the winding 64 and thereby disable the pump. The switch 68 may be a control switch of the character described in my aforesaid copending sole application. For example, the switch may be associated with the door to the refrigeration compartment in a manner such that the switch is closed when the door is opened, or the switch may be a thermostatically controlled switch which is closed when the refrigeration compartment is no longer in need of refrigeration. Alternatively, the switch 68 may be manually operable, if desired.

The winding 63 for effecting movement of the stop 6. to a slow idle position is connected by a wire 69 in circuit with the switch 68 and with the battery 67 so that when the pump is feathered the stop 61 is simultaneously moved to the normal engine idle position. In this manner, it will be seen that the carburetor linkage is maintained in a power idle position during such. time as the pump is not feathered or disabled and thus during such time as a load may be imposed on the engine by the pump, but when the pump is disabled or feathered, the carburetor linkage may return to a normal idle position. Fig. 3 illustrates the parts in a power idle position, and Fig. 4 illustrates the parts in a normal idle position.

I claim:

A drive for refrigeration systems including a compressor apparatus and an evaporator apparatus comprising, first and second hydraulic motors adapted for connection respectively with the compressor apparatus and the evaporator apparatus of said refrigeration system for driving the same, a hydraulic pump for supplying fluid under pressure to drive the hydraulic motors, a reservoir, a supply conduit connecting the reservoir and the pump inlet for supplying fluid to the pump, a first pressure conduit connecting the pump outlet and the first motor inlet, a second pressure conduit connecting the first motor outlet and the second motor inlet, whereby the pump and the first and second hydraulic motors are connected in series with each other, a return conduit connecting the outlet from the second hydraulic motor to the reservoir, a first bypass conduit connected to said first pressure conduit and said second pressure conduit in parallel with the first motor, valve means in said first bypass conduit normally closed to block fluid flow therethrough and openable for bypassing the first hydraulic motor and connecting the pump discharge directly to the second hydraulic motor to drive the latter separately, an electric motor mechanically connected to the first of the hydraulic motors and to said compressor apparatus, said electric motor being operable to drive the first hydraulic motor and the compressor apparatus when the pump is inoperative thereby to cause the first motor to pump fluid under pressure to drive the second hydraulic motor, a second bypass conduit connected to said supply conduit and to said first pressure conduit in parallel with the pump, and valve means in saidsecond bypass conduit normally closed to block flow therethrough and openable when the pump is inoperative and said electric motor is employed to drive the first hydraulic motor, to bypass the pump and connect the first hydraulic motor intake directly with the reservoir.

References Cited in the file of this patent UNITED STATES PATENTS 2,077,974 Wishart Apr. 20, 1933 2,104,696 Hanson Jan. 4, 1938 2,112,466 Maloon Mar. 29, 1938 2,264,821 Zukoski Dec. 2, 1941 2,518,316 Henny Aug. 8, 1950 2,530,241 Harrington Nov. 14, 1950 2,562,367 Robinson July 31, 1951 2,618,932 Taup Nov. 25, 1952 2,628,470 Orton Feb. 17, 1953 2,741,895 Horvath Apr. 17, 1956 2,746,240 Brown et al May 22, 1956 2,753,696 Guerra et a1. July 10, 1956