CN111750609A

CN111750609A - Two-phase oil cooling system

Info

Publication number: CN111750609A
Application number: CN202010240344.5A
Authority: CN
Inventors: 史蒂文·R·怀特曼; 雷金纳德·M·宾德尔; 史蒂文·R·萨斯; 萨科·H·福尤克; 埃里克·R·安德森
Original assignee: Deere and Co
Current assignee: Deere and Co
Priority date: 2019-03-28
Filing date: 2020-03-30
Publication date: 2020-10-09
Also published as: BR102020006222A2; US20200309467A1; DE102020204117A1

Abstract

The present disclosure provides a two-phase oil cooling system for a work vehicle. The system includes a condenser, an evaporator, a refrigerant path, and a pump. The condenser cools the refrigerant from a vapor form to a liquid form. The evaporator exchanges heat between a first fluid of the work vehicle and the refrigerant and heats the refrigerant from a liquid form to a vapor form. The refrigerant path includes a first refrigerant path thermally coupling the condenser to the evaporator and a second refrigerant path thermally coupling the evaporator to the condenser. The refrigerant flows through the refrigerant path. The pump is positioned in the first refrigerant path for pumping the refrigerant from the condenser to the evaporator such that the evaporator is downstream of the pump and the condenser is downstream of the evaporator.

Description

Two-phase oil cooling system

Technical Field

The present disclosure relates generally to a cooling system applied to a work vehicle.

Background

The off-highway industry uses various rotating parts: transmission, shaft, electric motor, hydraulic pump and motor, etc. These components may use oil as a working fluid and/or for lubrication and cooling. Rotating components of a work vehicle (e.g., a shaft or transmission) generate heat when operated. Traditionally, heat is partially removed by a cooling system/circuit that includes a radiator, a cooling fan, and an oil path coupled to the work vehicle. The hot cooling oil from the rotating parts flows into the radiator and is cooled by the radiator due to the cooling fan providing an air flow through a series of heat dissipating parts of the radiator. The cooled cooling oil flows back to the rotating parts later. However, since the oil is typically pumped outside of the rotating components to a remote single-phase oil and air heat exchanger for cooling, the cooling circuit is prone to leakage, contamination, pumping losses, and has a low heat transfer coefficient.

Disclosure of Invention

The present disclosure includes a two-phase oil cooling system that takes advantage of the benefits of being applied to an oil-cooled two-phase refrigerant having a significantly higher heat transfer coefficient. In addition, the present disclosure has the advantage of distributing the heat load from several components, and does not require pumping oil to a remote cooling system.

According to an aspect of the present disclosure, a two-phase oil cooling system for a work vehicle is provided. The two-phase oil cooling system includes a condenser, an evaporator, a refrigerant path, and a pump. The condenser cools the refrigerant from a vapor form to a liquid form. The evaporator exchanges heat between a first fluid of the work vehicle and the refrigerant, thereby heating the refrigerant from a liquid form to a vapor form. The refrigerant path includes a first refrigerant path thermally coupling the condenser to the evaporator and a second refrigerant path thermally coupling the evaporator to the condenser. The refrigerant flows through the refrigerant path. The pump is positioned in the first refrigerant path for pumping the refrigerant from the condenser to the evaporator such that the evaporator is downstream of the pump and the condenser is downstream of the evaporator.

In accordance with another aspect of the present disclosure, a two-phase oil cooling system for a work vehicle is provided. The two-phase oil cooling system includes a condenser, an evaporator, and a refrigerant path. The condenser cools the refrigerant from a vapor form to a liquid form. The evaporator is positioned below the condenser and exchanges heat between oil of a rotating component of the work vehicle and the refrigerant, thereby heating the refrigerant from a liquid form to a vapor form. The refrigerant path thermally couples the condenser to the evaporator. The refrigerant flows bi-directionally in the refrigerant path, driven by a difference in density of the refrigerant responsive to the temperature of the refrigerant within the refrigerant path, within the condenser and within the evaporator.

The present disclosure also provides a method for cooling a rotating component. The method comprises the following steps: pumping refrigerant at least partially in liquid form to an evaporator and moving refrigerant at least partially in vapor form to a condenser via the pumping such that a pressure of refrigerant flowing into the evaporator is higher than another pressure of refrigerant flowing into the condenser; absorbing heat from the oil in the rotating component by the evaporator to evaporate the refrigerant from a liquid form to a vapor form; and cooling the refrigerant at least partially in vapor form via the condenser.

Other features and aspects will become apparent by consideration of the detailed description and accompanying drawings.

Drawings

The detailed description of the drawings refers to the accompanying drawings in which:

FIG. 1 is a block diagram of a conventional cooling system applied to an air conditioner;

FIG. 2 is a simplified block diagram of a two-phase oil cooling system applied to a work vehicle;

FIG. 3 is a block diagram of the first embodiment of FIG. 2 having multiple evaporators;

FIG. 4 is a block diagram of the second embodiment of FIG. 2 having pump-condenser fan control logic;

FIG. 5 is a block diagram of the third embodiment of FIG. 2 having a separator that separates refrigerant in vapor form from refrigerant in liquid form;

FIG. 6 is a block diagram of the fourth embodiment of FIG. 2 having a separator that separates refrigerant in vapor form from refrigerant in liquid form, and the refrigerant in vapor form is processed in a compressor;

FIG. 7 is a block diagram of the fifth embodiment of FIG. 2, showing the evaporator positioned within the rotating member;

FIG. 8A is a block diagram of the sixth embodiment of FIG. 2 showing the evaporator positioned outside of the rotating component;

FIG. 8B is a perspective view of the evaporator of FIG. 8A;

FIG. 9A is a block diagram of an embodiment of a two-phase oil cooling system utilizing antifreeze flowing through an evaporator and a heat exchanger positioned within a rotating component;

FIG. 9B is a block diagram of an embodiment of a two-phase oil cooling system utilizing antifreeze flowing through an evaporator and a heat exchanger positioned outside of a rotating component;

FIG. 10 is a block diagram of an embodiment of a two-phase oil cooling system in which rotating component parts are connected in parallel;

FIG. 11 is a block diagram of the seventh embodiment of FIG. 2, showing a fan driven by refrigerant; and is

FIG. 12 is a block diagram of an embodiment of a two-phase oil cooling system utilizing buoyancy to drive refrigerant flow.

Detailed Description

Referring to fig. 1, a conventional cooling system applied to an air conditioner includes an evaporator 14 ', a compressor 24 ', a condenser 12 ', and a thermal expansion valve (TXV), through which refrigerant flows in liquid and/or vapor form at different pressures. The air conditioner is usually fixed to a wall of a house, and some elements of the air conditioner are indoors and some are outdoors. Typically, the compressor 24 'and condenser 12' of the air conditioner are located in an outdoor environment; a thermostatic expansion valve (TXV) and evaporator 14' are positioned in the indoor environment. The evaporator 14 'is located in the low pressure side (compressor suction side) and the condenser 12' is used in the high pressure side. A thermostatic expansion valve (TXV) is used between the condenser 12 'and the evaporator 14' to reduce the pressure.

In the path (suction line) between the evaporator 14 'and the compressor 24', the refrigerant is at a low pressure and temperature. In order for the compressor 24' to operate properly, the refrigerant is in vapor form (gas or superheated). When the refrigerant reaches the compressor 24 ', the compressor 24' compresses the refrigerant in vapor form so that the refrigerant in the path between the compressor 24 'and the condenser 12' is at a high pressure and temperature (possibly superheated). When the refrigerant reaches the condenser 12 ', the condenser 12' cools the temperature of the refrigerant and changes it to a liquid form via a fan (not shown). The fan provides a first air flow AF through the heat dissipating elements of the condenser 12₁'to remove heat from the condenser 12'. The refrigerant at the outlet of the condenser 12' must be a saturated or subcooled liquid for smooth operation of the thermostatic expansion valve (TXV). In the path between the condenser 12' and the thermal expansion valve (TXV), the refrigerant is still at high pressure.

A thermostatic expansion valve (TXV) later collects the refrigerant from the condenser 12'. In a thermostatic expansion valve (TXV), the pressure of the refrigerant drops sharply. The temperature of the refrigerant may also drop. Thus, in the path between the thermostatic expansion valve (TXV) and the evaporator 14', refrigeration is providedThe agent is at low Pressure (PL). The low pressure refrigerant flows into the evaporator 14'. Another fan (not shown) adjacent the evaporator 14' provides a second air flow AF through the heat exchange elements of the evaporator 14₂' (indoors). Second air flow AF₂' the heat is absorbed by the refrigerant, since the change of refrigerant in liquid form to vapor form requires latent heat (energy potential). Again, the refrigerant is discharged by the evaporator 14 'and flows into the compressor 24'.

FIG. 2 illustrates a simplified block diagram of a two-phase oil cooling system 10 for a work vehicle. In particular, the two-phase oil cooling system 10 is applied to at least one rotating component of a work vehicle (including a transmission, a shaft, an electric machine, a hydraulic pump, and a motor). The two-phase oil cooling system 10 includes a condenser 12, an evaporator 14, and a pump 20. The condenser 12 is used to cool the refrigerant from a vapor form to a liquid form. The evaporator 14 is used to exchange heat between oil and refrigerant of a rotating part of the work vehicle. The two-phase oil cooling system 10 also includes a refrigerant path 16, the refrigerant path 16 having a first refrigerant path 162 and a second refrigerant path 164. A first refrigerant path 162 thermally couples the condenser 12 to the evaporator 14 and a second refrigerant path 164 thermally couples the evaporator 14 to the condenser 12. The refrigerant flows through the refrigerant path 16. A pump 20 is positioned in the first refrigerant path 162 for pumping refrigerant from the condenser 12 to the evaporator 14, such that the evaporator 14 is downstream of the pump 20 and the condenser 12 is downstream of the evaporator 14. In other words, the pressure of the refrigerant intermediate the pump 20 and the evaporator 14 of the first refrigerant path 162 is a high pressure P_H(ii) a The pressure of the refrigerant in the second refrigerant path 164 is a low pressure P_L. The evaporator 14 is located in the high pressure side and the condenser 12 is located in the low pressure side. The reservoir (if any) is omitted from fig. 2.

First air flow AF₁Driven by the condenser fan 80 to cool the condenser 12, so that the refrigerant in vapor form flowing from the second refrigerant path 164 may be converted into liquid form. A pump 20 pumps the refrigerant into the evaporator 14. First oil flow OF flowing from or in a rotating part₁Transferring heat into the evaporator 14The refrigerant of (1). In the case OF refrigerant evaporation, a first oil flow OF₁And is thus cooled. The heated refrigerant later exits the evaporator 14 and enters the condenser 12 to be liquefied.

The following embodiments include a number of variations derived from fig. 2. The embodiments of the present disclosure may be modified and/or at least combined with each other to explain different configurations. Such variations and combinations will not depart from the spirit and scope of the present disclosure. For example, the pump 20 may be a two-phase flow pump, a positive displacement liquid pump, or may be combined with a compressor. The number of evaporators 14 may be one or more than one. Multiple evaporators 14 may be applied to one or more rotating members. The location of the evaporator 14 may be internal or external to the rotating component for exchanging heat between the refrigerant and the oil.

Referring to fig. 3, in a first embodiment of the present disclosure, the pump 20 is a two-phase flow pump having the capability to pump refrigerant in vapor and liquid form. Because the pump 20 is compatible with both forms of refrigerant in this embodiment, it can avoid cavitation that occurs when some refrigerant in vapor form is in the liquid pump. Therefore, even when the condenser 12 cannot completely convert the refrigerant in the form of vapor into the form of liquid in this embodiment, the pump 20 can be operated smoothly to pump the refrigerant into the evaporator 14. There are a plurality of evaporators 14 each of which is applied to a respective one of the rotating members (not shown in fig. 3). In addition, in this embodiment, the first refrigerant path 162 divides the plurality of first sub-refrigerant paths 1622, and the second refrigerant path 164 divides the plurality of second sub-refrigerant paths 1642. Each of the evaporators 14 is coupled to one of the first sub-refrigerant paths 1622 and to one of the second sub-refrigerant paths 1642. Each of the first sub-refrigerant paths 1622 has a flow control valve 40 positioned to control the flow in a corresponding one of the evaporators 14. In this regard, the four evaporators 14 may have different refrigerant flow rates, and thus the heat exchange efficiency in the evaporators 14 is different. An appropriate amount of refrigerant can be distributed in the evaporator 14 using the flow control valve 40. The control of the flow control valve 40 relates to the degree of necessity for the rotating parts at which the evaporator 14 is coupled. For one example, if one of the rotating components is a front axle and the other of the rotating components is a rear axle, and if there is a mode change from four-wheel drive to front-wheel drive in the work vehicle, the flow control valve 40 applied to the front axle will increase the flow rate of the refrigerant and the flow control valve 40 applied to the rear axle will decrease the flow rate of the refrigerant. The flow control valves 40 are operated via commands of a controller (not shown) that adjusts the plurality of flow control valves 40 based on the load of the rotating parts. For another example, if the temperature of one rotating component is higher than the temperature of the other, the flow control valve 40 allows a greater refrigerant flow than the other flow control valve 40 of the other rotating component. When the flow control valve 40 is a temperature control valve, or a flow control valve 40 coupled to a thermometer and/or a flow pressure sensor, this operation may be performed in cooperation with a controller (not shown) that controls the flow based on a preset plurality of criteria including temperature, flow pressure, durability of rotating parts, and the like. Alternatively, multiple evaporators 14 may be applied to a single rotating component to cool different portions of the rotating component.

Reference is made to fig. 4, which is a second embodiment of fig. 2. In this embodiment, the features are similar to FIG. 3, except that the pump 20 is a positive displacement liquid pump, and the two-phase oil cooling system 10 further includes a controller 70, the controller 70 having a pump-condenser fan control logic circuit 72. Pump-condenser fan control logic 72 is connected to pump 20 and condenser fan 80. To ensure that most of the refrigerant exiting the condenser 12 has been converted to liquid form to prevent cavitation from occurring in the pump 20, the pump-condenser fan control logic 72 regulates the condenser 12 to cool the refrigerant before the pump 20 pumps the refrigerant. In this regard, the condenser 12 subcools or saturates the refrigerant before the refrigerant reaches the pump 20.

Reference is made to fig. 5, which is a third embodiment of fig. 2. In this embodiment, the pump 20 is a positive displacement liquid pump. The two-phase oil cooling system 10 also includes a separator 22, a reverse refrigerant path 166, and a reverse flow control valve 42 positioned in the reverse refrigerant path 166. The separator 22 is positioned in the first refrigerant path 162 between the condenser 12 and the pump 20, and is configured to separate refrigerant in vapor form from refrigerant in liquid form, and to permit refrigerant in liquid form to flow through the pump 20. The remainder of the refrigerant in vapor form flows from the separator 22 to the second refrigerant path 164 through the reverse refrigerant path 166. A reverse flow control valve 42 (e.g., a check valve) controls the flow of refrigerant in vapor form in the reverse refrigerant path 166. The reverse flow control valve 42/check valve may be used to reduce the pressure in the separator 22 in the event of excessive refrigerant accumulation in vapor form. The refrigerant returning to the second refrigerant path 164 will be cooled again in the condenser 12. The reverse flow control valve 42 may be optional if the pump-condenser fan control logic 72 in the second embodiment is applied to this embodiment. The reverse flow control valve 42 may be optional if the size of the condenser 12 is large enough.

Note that the features in the second and third embodiments may be combined (refer to fig. 4 and 5). Pump-condenser fan control logic 72 is connected to pump 20 and condenser fan 80. The pump-condenser fan control logic 72 regulates the condenser 12 to cool the refrigerant before the pump 20 pumps the refrigerant. In this regard, the condenser 12 may cool the refrigerant before the refrigerant reaches the pump 20. Even if refrigerant in vapor form is still present after operation of the condenser 12, the refrigerant in vapor form will be separated by the separator 22 and returned to the second refrigerant path 164, as previously described. The combination further prevents cavitation of the pump 20 when the pump 20 is a liquid pump.

Reference is made to fig. 6, which is a fourth embodiment of fig. 2. In this embodiment, the pump 20 is a positive displacement liquid pump. The two-phase oil cooling system 10 also includes a separator 22, a compressor path 1624 coupling the separator 22 to the first refrigerant path 162, and a compressor 24 positioned in the compressor path 1624. The compressor 24 compresses refrigerant in vapor form that flows from the separator 22 to the evaporator 14 via a compressor path 1624. The pump 20 pumps the refrigerant in liquid form flowing from the separator 22 to the evaporator 14 through the first refrigerant path 162. In this embodiment, the compressor path 1624 later merges into the first refrigerant path 162, mixing the refrigerant in vapor and liquid form. The compressor path 1624 is parallel to the first refrigerant path 162 from the separator 22 to the pump 20 such that the refrigerant in vapor form separated by the separator 22 does not flow into the pump 20, the pump 20 being a liquid pump. In this regard, even if the rotating components are at a high thermal load and the condenser 12 is unable to condense all of the refrigerant to liquid form by virtue of energy consumed by another component (i.e., an energy recovery unit, described in the next paragraph), the refrigerant in vapor form may be directed to the compressor path 1624 without damaging the pump 20. Unlike conventional cooling systems, as depicted in fig. 1, in which refrigerant flows from the evaporator 14 ' to the condenser 12 ' through the compressor 24 ', in this embodiment, refrigerant (in vapor form) flows from the condenser 12 to the evaporator 14 through the compressor 24.

Referring again to FIG. 6, the two-phase oil cooling system 10 includes the energy recovery unit 30 positioned in the second refrigerant path 164. In this embodiment, an energy recovery unit 30 is installed between the evaporator 14 and the condenser 12. The energy recovery unit 30 includes a turbine 32 driven by the refrigerant. In this embodiment, the turbine 32 is a two-phase flow turbine adapted to work with refrigerant in vapor and liquid form. The energy recovery unit 30 may include at least one of a secondary pump 34 and a generator 36 coupled to the turbine 32. The turbine 32 absorbs some of the energy from the refrigerant and drives a secondary pump 34 and a generator 36. In one aspect, the turbine 32 may convert the energy potential in the refrigerant in vapor form to shaft power. Shaft power is used to rotate the secondary pump 34 and the generator 36. In another aspect, the turbine 32 may also utilize the flow of refrigerant in liquid or vapor form induced by the pump 20 to increase shaft power. In this way, the energy recovery unit 30 not only reuses the excess energy of the refrigerant, but also shares the duty of the condenser 12, as a portion of the energy is removed. Thus, a greater percentage of the refrigerant in vapor form is converted to liquid form. Unlike conventional cooling systems having a thermal expansion valve (TXV) that can reduce the refrigerant flow rate as depicted in fig. 1, the second refrigerant path 164 coupled to the condenser 12 and the evaporator 14 does not necessarily have to have a thermal expansion valve (TXV).

When the energy recovery unit 30 includes the secondary pump 34, the secondary pump 34 may pump another liquid for additional functions. For example, the secondary pump 34 may be an oil pump 66 as shown in fig. 8A. Thus, the secondary pump 34/oil pump 66 may pump oil from the rotating components 60, as will be described in detail later. Referring to fig. 6, when the energy recovery unit 30 includes the generator 36, the generator 36 may be further coupled to a battery or other electrical component (not shown).

Note that the energy recovery unit 30 may also be applied to the second refrigerant path 164 in the configurations of fig. 3 to 5 or other variations of fig. 2.

Referring to fig. 7, this is the fifth embodiment of fig. 2. In this embodiment, a rotating member 60 is used for illustration; however, the two-phase oil cooling system 10 may have more than one rotating member 60. The evaporator 14 is at least partially submerged in oil 62 within the rotating components 60 of the work vehicle. When the rotating member 60 is operated, the oil 62 is driven to flow along at least one surface of the evaporator 14 to increase the heat exchange rate. By way of example, the rotary member 60 is a front axle, wherein a gear set, differential, shaft, etc. is rotating and is driving oil 62 to flow rapidly within the rotary member 60, and thus such a configuration improves heat exchange between the refrigerant in the evaporator 14 and the oil 62 in the rotary member 60. The relative position between the evaporator 14 and the rotary member 60 can be applied to the other variations of fig. 2.

Referring to fig. 8A, this is the sixth embodiment of fig. 2. In this embodiment, a rotating member 60 is used for illustration; however, the two-phase oil cooling system 10 may have more than one rotating member 60. Fig. 8A shows only one evaporator 14, but the number of evaporators 14 may be applied in a large number on a single or multiple rotating members 60 depending on the actual design. In this embodiment, the evaporator 14 is positioned outside the rotating member 60. The two-phase oil cooling system 10 further includes an oil pump 66, a first oil path 642, and a second oil path 644. Oil of rotary part 60 (to be shown in fig. 8B) is in fluid communication with rotary part 60 and evaporator 14 via first oil path 642 and second oil path 644 that couple rotary part 60 to evaporator 14. The oil pump 66 is positioned in the first oil path 642, and the oil pump 66 pumps oil from the rotary member 60 to the evaporator 14. The two-phase oil cooling system 10 can further include an oil filter 68, and the oil filter 68 can be positioned in either of the first oil path 642 and the second oil path 644. In this embodiment, the oil filter 68 is positioned in the second oil path 644. In this configuration, the oil flow is not only cooled during heat exchange in the evaporator 14, but also cleaned during filtration in the oil filter 68. Thus, the oil exiting from the evaporator 14 is hot, with impurities, but as it flows back to the evaporator 14, it is cooled and cleaned.

The positioning of the evaporator 14 outside the rotating member 60 allows for easy maintenance by an operator. The filtration process also extends the life of the rotating components 60. The sixth embodiment of the two-phase oil cooling system 10 may be used in work vehicles that are typically used in demanding duty applications.

Referring to fig. 8B, a perspective view of the evaporator 14 is illustrated, wherein the refrigerant is designated 15 and the oil is designated 62. The evaporator 14 includes a refrigerant passage 142, and the refrigerant 15 flows through the refrigerant passage 142. The refrigerant channel 142 thermally couples the first refrigerant path 162 to the second refrigerant path 164. The evaporator 14 also includes an oil passage 144, and the oil 62 flows through the oil passage 144. The oil passage 144 thermally couples the first oil path 642 to the second oil path 644. The refrigerant passage 142 and the oil passage 144 are at least close to or joined to each other to exchange heat. It is also noted that in at least a portion of the refrigerant passage 142 and in at least a portion of the oil passage 144, the refrigerant 15 and the oil 62 flow in opposite directions.

Referring to FIG. 9A, another embodiment of a two-phase oil cooling system 10 is shown. Instead of circulating the refrigerant 15 around the work vehicle and exchanging heat directly with the oil 62 at the evaporator 14, the two-phase oil cooling system 10 may include one or more fluids (circuits) to absorb heat from the oil and be cooled by the refrigerant 15. The condenser 12, separator 22, pump 20, evaporator 14, and refrigerant 15 may be similar to those shown in fig. 8. In this embodiment, the rotating members include a first rotating member 602, a second rotating member 604, and a third rotating member 606. Two-phase oil cooling system 10 includes a first heat exchanger 902, a second heat exchanger 904, and a third heat exchanger 906 submerged in the oil of first rotating component 602, second rotating component 604, and third rotating component 606, respectively. The two-phase oil cooling system may also include an antifreeze path 94, the antifreeze path 94 coupling the evaporator 14 to the first heat exchanger 902, the second heat exchanger 904, and the third heat exchanger 906. The antifreeze 92 is in fluid communication with the evaporator 14 and the first, second, and

third heat exchangers

902, 904, 906 via an antifreeze path 94. Additionally, an antifreeze pump 96 is positioned in the antifreeze path 94 and is configured to pump the antifreeze 92 to the evaporator 14.

In this embodiment, the antifreeze 92 is ethylene glycol. Antifreeze 92 absorbs heat from the oil of first, second, and third

rotary components

602, 604, 606 in first heat exchanger 902, second heat exchanger 904, and third heat exchanger 906. The heated antifreeze 92 then flows to the evaporator 14 to heat the refrigerant from a liquid form to a vapor form, such that the cooled antifreeze 92 may again flow to the

heat exchangers

902, 904, 906 to cool the oil in the first, second, and third

rotary members

602, 604, 606.

Alternatively, referring to fig. 9B, first, second, and

third heat exchangers

902, 904, 906 are positioned outside of first, second, and third

rotary components

602, 604, 606. Oil is in fluid communication with first heat exchanger 902, second heat exchanger 904, third heat exchanger 906, and first rotating component 602, second rotating component 604, and third rotating component 606. In this embodiment, an oil pump (not shown) may be positioned in the oil path between first heat exchanger 902, second heat exchanger 904, third heat exchanger 906, and first rotating component 602, second rotating component 604, and third rotating component 606. The oil pump may pump oil from the rotating member. The oil is cooled in

heat exchangers

902, 904, 906 via antifreeze 92.

In fig. 9A and 9B, the rotating

members

602, 604, 606 are connected in series. As the antifreeze 92 flows from the first rotating member 602 to the third rotating member 606, the temperature of the antifreeze 92 increases. Such an arrangement may be based on heat transfer requirements and maximum oil temperature requirements. For example, first rotating component 602 may need to dissipate heat faster than second rotating component 604 and third rotating component 606. For example, third rotary component 606 may require a cooling fluid (i.e., antifreeze) above a certain temperature to ensure that the temperature of the oil is above a certain temperature. Alternatively, the

rotational components

602, 604, 606 may be parallel or partially parallel, as shown in fig. 10, as desired.

Referring to fig. 11, note that a condenser fan 80 may be coupled to the refrigerant path 16. Condenser fan 80 is positioned in second refrigerant path 164. In other words, the condenser fan 80 is downstream of the evaporator 14, but upstream of the condenser 12. Because the refrigerant is at least partially converted to vapor form as previously described, the volumetric expansion of the refrigerant may be used to rotate the condenser fan 80. In this regard, the fan 80 may rotate without power from other sources or with relatively low power from other sources (not shown). This configuration can be applied to various embodiments having a path between the evaporator and the condenser.

Referring to FIG. 12, another embodiment of a two-phase oil cooling system 10 utilizing buoyancy to drive refrigerant is illustrated. In this embodiment, the pump 20 is not required. Unlike the previous embodiment, which has a pump 20 and the relative position between the condenser 12 and the evaporator 14 in height is flexible, in this embodiment the condenser 12 is positioned higher than the evaporator 14. In this embodiment, the two-phase oil cooling system 10 includes a condenser 12, an evaporator 14, a refrigerant path 16, a controller 70, and a condenser fan 80. A refrigerant path 16 thermally couples the condenser 12 to the evaporator 14. Because the temperature of the refrigerant passing through or near the condenser 12 is lower than the temperature of the refrigerant passing through or near the evaporator 14, the refrigerant passing through or near the condenser 12 moves downward and the refrigerant passing through or near the evaporator 14 moves upward. In this regard, the refrigerant is able to flow in both directions in the refrigerant path 16. The refrigerant is driven by a difference in density of the refrigerant responsive to the temperature of the refrigerant in the refrigerant path 16, in the condenser 12, and in the evaporator 14.

The two-phase oil cooling system 10 further includes a temperature sensor 122 to measure a temperature of the refrigerant in at least one of the condenser 12, the evaporator 14, and the refrigerant path 16. In the embodiment shown in fig. 12, a temperature sensor 122 is positioned in the condenser 12 to measure the temperature of the refrigerant and is electrically connected to the controller 70. The controller 70 adjusts the condenser fan 80 operating speed based on the temperature of the refrigerant in the condenser 12. If the temperature of the refrigerant in the condenser 12 is relatively higher than its normal operating temperature, the refrigerant exiting the evaporator 14 may carry more heat and, therefore, the condenser fan 80 accelerates to provide a stronger first air flow AF₁To ensure that there is a substantial difference in the density of the refrigerant between the condenser 12 and the evaporator 14. In this regard, the circulation of the refrigerant is ensured in this embodiment even without a pump as shown in the previous embodiments.

The present disclosure also provides a method for cooling a rotating component:

step 1: the refrigerant, at least partly in liquid form, is pumped via a pump to the evaporator and further to the condenser, so that the pressure of the refrigerant flowing into the evaporator is higher than the other pressure of the refrigerant flowing into the condenser.

When the pump is a liquid pump, step 1 further comprises separating refrigerant in vapor form from refrigerant in liquid form to permit refrigerant in liquid form to flow through the pump. The refrigerant in vapor form is provided in two ways:

(1) transferring the refrigerant in vapor form back to the condenser through a reverse refrigerant path; or

(2) The refrigerant in vapor form is compressed via a compressor to an evaporator.

Step 2: heat from the oil from the rotating components is absorbed by the evaporator to evaporate the refrigerant from a liquid form to a vapor form.

Step 2 also includes immersing the evaporator in oil within the rotating member. In operation of the rotating member, oil is driven to flow along at least one surface of the evaporator to increase the heat exchange rate.

Alternatively, step 2 comprises pumping oil from the rotating parts to the evaporator by means of an oil pump to exchange heat between the oil and the refrigerant. This step also includes filtering the oil through an oil filter using the oil pressure generated by the oil pump.

Step 2 may also include recovering energy from the refrigerant leaving the evaporator. The turbine is driven by the refrigerant.

And step 3: the refrigerant, at least partially in vapor form, is cooled via a condenser.

The above mentioned steps will be repeated to cool the oil in the rotating parts.

Several examples of the invention are given below and numbered.

1. There is provided a two-phase oil cooling system for a work vehicle, comprising:

a condenser configured to cool a refrigerant from a vapor form to a liquid form;

an evaporator configured to exchange heat between a first fluid of the work vehicle and the refrigerant, thereby heating the refrigerant from a liquid form to a vapor form;

a refrigerant path comprising a first refrigerant path thermally coupling the condenser to the evaporator and a second refrigerant path thermally coupling the evaporator to the condenser, the refrigerant configured to flow through the refrigerant path; and

a pump positioned in the first refrigerant path for pumping the refrigerant from the condenser to the evaporator such that the evaporator is downstream of the pump and the condenser is downstream of the evaporator.

2. The two-phase oil cooling system for a work vehicle according to example 1, wherein the first fluid is oil of a rotating member of the work vehicle.

3. The two-phase oil cooling system for a work vehicle of example 2, wherein the evaporator is at least partially submerged in the oil within rotating components of the work vehicle.

4. The two-phase oil cooling system for a work vehicle according to example 3, wherein when the rotating member is operated, the oil is driven to flow on at least one surface of the evaporator in a turbulent manner to improve a heat exchange rate.

5. The two-phase oil cooling system for a work vehicle according to example 2, wherein the evaporator is positioned outside the rotating member, and the oil of the rotating member is in fluid communication with the rotating member and the evaporator via a first oil path and a second oil path that couple the rotating member to the evaporator.

6. The two-phase oil cooling system for a work vehicle according to example 5, wherein the evaporator includes:

a refrigerant passage through which the refrigerant flows and which thermally couples the first refrigerant path to the second refrigerant path; and

an oil passage through which the oil flows and which thermally couples the first oil path to the second oil path, and the refrigerant passage and the oil passage are at least proximate to or engaged with each other to exchange heat.

7. The two-phase oil cooling system for a work vehicle according to example 6, comprising: an oil pump positioned in the first oil path and pumping the oil from the rotating component to the evaporator.

8. The two-phase oil cooling system for a work vehicle according to example 7, comprising: an oil filter positioned in one of the first oil path and the second oil path to filter oil of the rotating component.

9. The two-phase oil cooling system for a work vehicle of example 1, wherein the pump is a two-phase flow pump that pumps the refrigerant in liquid form and vapor form.

10. The two-phase oil cooling system for a work vehicle of example 1, comprising a separator positioned in the first refrigerant path between the condenser and the pump and configured to separate refrigerant in vapor form from refrigerant in liquid form to permit refrigerant in liquid form to flow through the pump.

11. The two-phase oil cooling system for a work vehicle according to example 10, comprising: a reverse refrigerant path coupling the separator to the second refrigerant path,

refrigerant in vapor form flows from the separator to the second refrigerant path through the reverse refrigerant path.

12. The two-phase oil cooling system for a work vehicle of example 11, comprising a reverse flow control valve positioned in the reverse refrigerant path.

13. The two-phase oil cooling system for a work vehicle according to example 10, comprising:

a compressor path coupling the separator to the first refrigerant path; and

a compressor positioned in the compressor path, the compressor compressing refrigerant in vapor form flowing from the separator to the evaporator through the compressor path, and the pump pumping refrigerant in liquid form flowing from the separator to the evaporator through the first refrigerant path.

14. The two-phase oil cooling system for a work vehicle according to example 13, comprising: an energy recovery unit positioned in the second refrigerant path, the energy recovery unit including a turbine driven by the refrigerant.

15. The two-phase oil cooling system for a work vehicle of example 14, wherein the energy recovery unit comprises one of a secondary pump and a generator coupled to the turbine.

16. The two-phase oil cooling system for a work vehicle according to example 1, comprising: an energy recovery unit positioned in the second refrigerant path,

the energy recovery unit includes: a turbine driven by the refrigerant, and one of a secondary pump and a generator coupled to the turbine.

17. The two-phase oil cooling system for a work vehicle according to example 2, comprising: a flow control valve positioned in a first refrigerant path between the pump and the evaporator, the flow control valve operating based on a temperature of the oil.

18. The two-phase oil cooling system for a work vehicle according to example 17, comprising: more than one of the evaporators and more than one rotary member having oil, wherein the first refrigerant path is divided into a plurality of first sub-refrigerant paths, the second refrigerant path is divided into a plurality of second sub-refrigerant paths, and each of the evaporators is coupled to one of the first sub-refrigerant paths and one of the second sub-refrigerant paths, and heat is exchanged between the oil of one of the rotary members and the refrigerant flowing through the evaporator.

19. The two-phase oil cooling system for a work vehicle according to example 18, comprising: more than one flow control valve, each flow control valve positioned into a respective one of the first sub-refrigerant paths, the flow control valves configured to control refrigerant flowing in the first sub-refrigerant path.

20. The two-phase oil cooling system for a work vehicle according to example 1, comprising:

a condenser fan configured to cool the condenser; and

a pump-condenser fan control logic circuit coupled to the pump and the condenser, and configured to condition the condenser to cool the refrigerant before the pump pumps the refrigerant.

21. The two-phase oil cooling system for a work vehicle according to example 1, comprising: a heat exchanger configured to exchange heat between the first fluid and oil of a rotating component of the work vehicle.

22. The two-phase oil cooling system for a work vehicle of example 21, wherein the first fluid is antifreeze, the evaporator is positioned outside of the rotating component, the first fluid is in fluid communication with the evaporator and the heat exchanger via an antifreeze path, the antifreeze path couples the evaporator to the heat exchanger.

23. The two-phase oil cooling system for a work vehicle of example 22, further comprising: an antifreeze pump positioned in the antifreeze path and configured to pump the antifreeze to the evaporator.

24. The two-phase oil cooling system for a work vehicle according to example 1, comprising: a condenser fan configured to cool the condenser, the condenser fan positioned downstream of the evaporator and upstream of the condenser such that the condenser fan is driven at least in part by volumetric expansion of the refrigerant.

25. There is provided a two-phase oil cooling system for a work vehicle, comprising:

an evaporator positioned below the condenser and configured to exchange heat between the refrigerant and oil of a rotating component of the work vehicle, thereby heating the refrigerant from a liquid form to a vapor form; and

a refrigerant path thermally coupling the condenser to the evaporator, the refrigerant configured to flow bi-directionally in the refrigerant path, driven by a density difference of refrigerant generated in response to a temperature of refrigerant within the refrigerant path, within the condenser, and within the evaporator.

26. A method for cooling a rotating component is provided, comprising:

pumping refrigerant at least partially in liquid form to an evaporator and moving refrigerant at least partially in vapor form to a condenser via the pumping such that a pressure of refrigerant flowing into the evaporator is higher than another pressure of refrigerant flowing into the condenser;

absorbing heat from the oil in the rotating component by the evaporator to evaporate the refrigerant from a liquid form to a vapor form; and

cooling, via the condenser, the refrigerant at least partially in vapor form.

Without in any way limiting the scope, interpretation, or application of the claims appearing below, a technical effect of one or more of the example embodiments disclosed herein is to cool the oil in the rotating components with a higher heat transfer coefficient refrigerant to achieve better cooling performance. Another technical effect of one or more of the example embodiments disclosed herein is distributing heat load from one or more rotating components without oil being pumped to a remote location of the work vehicle. Another technical effect of one or more of the example embodiments disclosed herein is a reduced chance of oil leakage.

As used herein, unless otherwise limited or modified, a list of elements that have an element separated by a conjunctive term (e.g., "and") and preceded by the phrase of at least one of the ". or". one or more of the ". indicate a configuration or arrangement that potentially includes individual elements of the list, or any combination thereof. For example, "at least one of A, B and C" or "one or more of A, B and C" indicates the possibility of any combination of two or more of A only, B only, C only, or A, B and C (e.g., A and B; B and C; A and C; or A, B and C).

While the foregoing describes example embodiments of the present disclosure, these descriptions should not be viewed in a restrictive or limiting sense. Rather, other changes and modifications may be made without departing from the scope and spirit of the disclosure as defined in the appended claims.

Claims

1. A two-phase oil cooling system for a work vehicle, comprising:

2. The two-phase oil cooling system for a work vehicle of claim 1, wherein the first fluid is oil of a rotating component of the work vehicle.

3. The two-phase oil cooling system for a work vehicle of claim 2, wherein the evaporator is at least partially submerged in the oil within rotating components of the work vehicle.

4. The two-phase oil cooling system for a work vehicle of claim 2, wherein the evaporator is positioned outside of the rotating component and the oil of the rotating component is in fluid communication with the rotating component and the evaporator via a first oil path and a second oil path that couple the rotating component to the evaporator.

5. The two-phase oil cooling system for a work vehicle of claim 1, wherein the pump is a two-phase flow pump that pumps the refrigerant in liquid form and vapor form.

6. The two-phase oil cooling system for a work vehicle of claim 1, comprising a separator positioned in the first refrigerant path between the condenser and the pump and configured to separate refrigerant in vapor form from refrigerant in liquid form to permit refrigerant in liquid form to flow through the pump.

7. The two-phase oil cooling system for a work vehicle of claim 6, comprising: a reverse refrigerant path coupling the separator to the second refrigerant path,

8. The two-phase oil cooling system for a work vehicle of claim 6, comprising:

a compressor path coupling the separator to the first refrigerant path; and

9. The two-phase oil cooling system for a work vehicle according to claim 1, comprising: an energy recovery unit positioned in the second refrigerant path,

10. The two-phase oil cooling system for a work vehicle according to claim 2, comprising: a flow control valve positioned in a first refrigerant path between the pump and the evaporator, the flow control valve operating based on a temperature of the oil.

11. The two-phase oil cooling system for a work vehicle according to claim 1, comprising:

a condenser fan configured to cool the condenser; and

12. The two-phase oil cooling system for a work vehicle according to claim 1, comprising: a heat exchanger configured to exchange heat between the first fluid and oil of a rotating component of the work vehicle.

13. The two-phase oil cooling system for a work vehicle of claim 12, wherein the first fluid is antifreeze, the evaporator is positioned outside of the rotating component, the first fluid is in fluid communication with the evaporator and the heat exchanger via an antifreeze path, the antifreeze path couples the evaporator to the heat exchanger.

14. The two-phase oil cooling system for a work vehicle according to claim 1, comprising: a condenser fan configured to cool the condenser, the condenser fan positioned downstream of the evaporator and upstream of the condenser such that the condenser fan is driven at least in part by volumetric expansion of the refrigerant.

15. A two-phase oil cooling system for a work vehicle, comprising:

16. A method for cooling a rotating component, comprising:

cooling, via the condenser, the refrigerant at least partially in vapor form.