WO2018138717A1

WO2018138717A1 - Device and method for hybrid vehicle range extending

Info

Publication number: WO2018138717A1
Application number: PCT/IL2018/050055
Authority: WO
Inventors: Samuel Koeger; Jonathan Schneider
Original assignee: Beth El Zikhron Yaaqov Industries Ltd
Current assignee: Beth El Zikhron Yaaqov Industries Ltd
Priority date: 2017-01-30
Filing date: 2018-01-15
Publication date: 2018-08-02
Anticipated expiration: 2019-07-30
Also published as: IL250368B; IL250368A0

Abstract

The present invention provides a battery cooling system for hybrid vehicle and an operation method thereof, that contributes to extending the hybrid vehicle range of travel or time of operation. The battery cooling system includes: a liquid cooled battery pack [32] (fig. 1) and a liquid coolant located in a cooling space [26] between battery cells [22]. According to the invention, the liquid coolant is suitable as an internal combustion engine fuel, and the hybrid vehicle [10] can use the liquid coolant to run an internal combustion engine [24]. The liquid coolant may be used to run the internal combustion engine [24] after the battery pack [32] is drained of electric power.

Description

DEVICE AND METHOD FOR HYBRID VEHICLE RANGE EXTENDING

FIELD OF THE INVENTION

The present invention relates to a battery cooling system and a method, for extending the drive range of a hybrid vehicle, more particularly to extending the drive range of a hybrid vehicle by using a fuel based battery coolant suitable as a running fuel of an internal combustion engine.

BACKGROUND OF THE INVENTION

Hybrid vehicles uses two distinct types of power, such as internal combustion engine and electric motor.

Several types of hybrid systems are in use, mainly the serial and parallel:

The parallel hybrid, incorporates an electric motor powered from a battery pack and an internal combustion engine running on fuel. The motor and engine are mechanically coupled such that they can drive the vehicle transmission either individually or together.

The series hybrid, incorporates an electric motor, capable of driving the vehicle transmission individually, using battery pack energy when available, and using electric energy generated locally when the battery pack energy is drained. Electric power is generated by a separate internal combustion engine running on fuel, coupled to an electric generator.

Hybrid systems use regenerative braking where braking power is transmitted to electric power and stored in the battery pack for later use. Hybrids are intended to reduce pollution and noise and to increase efficiency and travel range per liter of liquid fuel, whether gasoline or diesel fuel.

Typically the travel range is influenced as function of load weight, road topology, environmental temperature and drive conditions. Hybrid systems by nature increase the total range of travel of a given vehicle by means of generative braking, higher efficiency in operation, lighter engine and reduced volume of the fuel tank. However, sometimes like in military use of hybrid vehicles there is a need to extend the travel range even further by disabling some safety features of the hybrid system. For example in military hybrid vehicles on emergency, the operator can override the battery management system and heat or drain the battery to an extent that may degrade the battery life or energy storage capacity.

A fundamental restriction on battery performance is temperature. Battery cells especially lithium batteries are best suited to operate in a limited optimum temperature range. The life expectancy and durability of the battery, as well as the performance can be significantly degraded by temperatures above the allowable temperature limit. Accordingly it is known in the art that hybrid vehicle battery packs need some type of cooling, whether air cooling or preferably more efficient liquid cooling. Liquid cooling systems can be distinguished by use of electric conductive or electric isolating coolants. Electric conductive coolants such as water or mixture of water and ethylene-glycol have high level of thermal conductivity but on the other hand they must be electrically insulated from electrically charged battery cell elements. Unfortunately the additional electric insulator is also a thermal barrier between the electric conductive coolant and the electrically charged battery cell elements. Non conductive coolants such as various types of oil (silicone or mineral) have lower heat conductivity but can be in direct contact with electrically charged battery elements. Such a system is described for instance in US patent application 2013/0260195.

Both types of liquid cooling systems described above are using a closed coolant loop where the liquid is circulated between the battery pack and an external heat exchanger suitable to dissipate the excessive heat.

For effective cooling, a certain amount of liquid coolant per W/hour of battery capacity is required for the circulation loop. The volume of coolant is an additional undesired load that reduces the total performance in terms of energy and travel range.

It is desired that the coolant capacity will contribute to extend the travel range and that such increase in travel range will not degrade the battery life or the energy storage capacity.

SUMMARY OF THE INVENTION

Accordingly, it is a principal object of the present invention to overcome the disadvantages and limitations of prior art systems and provide a battery cooling system that can contribute to extending the hybrid vehicle range of travel or time of operation.

According to the present invention there is provided a battery cooling system and a method for extending the drive range of a hybrid vehicle. The system includes: a liquid cooled battery pack and a liquid coolant; wherein the liquid coolant is suitable as an internal combustion engine fuel, and wherein the hybrid vehicle can use the liquid coolant to run an internal combustion engine.

The method for extending the range of a hybrid vehicle includes the steps of:

a) providing a liquid cooled battery pack;

b) filling the battery pack coolant loop with a liquid coolant usable as an internal combustion engine fuel; and

c) propelling the hybrid vehicle by an internal combustion engine running on the liquid coolant taken out of said battery pack coolant loop.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and the way it may be carried out in practice, will be understood with reference to the following illustrative figures, by way of non-limiting example only, in which like reference numerals identify like elements, and in which:

Fig. 1 is a schematic presentation of a hybrid vehicle making use of a battery cooling system made according to an embodiment of the present invention;

Fig. 2 is a schematic presentation of a battery pack with optional air cooling; and

Fig. 3 is a schematic presentation of a battery pack with optional liquid cooling using relatively small amount of the coolant content.

DETAILED DESCRIPTION OF EMBODIMENTS

With reference to the figures, in which like reference numerals identify like elements, there is shown in Fig. 1, a schematic presentation of a hybrid vehicle generally referenced 10, making use of a range extending system made according to one embodiment of the present invention.

With reference to Fig. 1, the hybrid vehicle 10 like most hybrid vehicles, includes an electric motor 20, an internal combustion engine 24, a transmission 28 coupled to the electric motor 20 and to the engine 24, a liquid cooled battery pack 32 housing a plurality of battery cells 22, a heat exchanger 36 and a primary fuel tank 40. The battery pack 32 is electrically connected to the electric motor 20 by cable 38 and optional power management controller 34. The range extending system specific to the present invention comprises the liquid cooled battery pack 32 and heat exchanger 36, fluidly linked by coolant pipe 58 and circulating pump 42. The coolant loop, generally referenced 16, circulating through the above elements, is filled with a liquid coolant which is suitable as an internal combustion engine fuel. Accordingly, the hybrid vehicle of the present invention can use the liquid coolant of the battery pack 32 coolant loop 16 to run the internal combustion engine 24, thus permitting additional drive range or time of operation after the battery pack 32 is drained of electric energy and the primary fuel tank 40 is emptied. For the purpose of the present invention, the term "range extending" means not only the drive range normally expressed in kilometers or miles, but also the time range in terms of hours of operation of the electric motor or the internal combustion engine, or even use of the liquid coolant as fuel for any other use like operation of an auxiliary power unit (APU). For example a vehicle idling or generating electric power for a longer period of time as a result of using the system of the present invention is also covered by the term "range extending".

The battery pack 32 coolant loop generally referenced 16, typically includes the battery pack cooling space 26 located between the battery cells 22, a heat exchanger 36 located locally on top of the battery pack or remotely in position of improved air flow, coolant pipe 58 and a circulating pump 42. The heat exchanger is typically cooled by native air flow with the assistance of an air moving fan 44 automatically turning on when the temperature of the heat exchanger reaches a certain high level.

In operation, according to one aspect of the present invention, the hybrid vehicle 10 is using first the electric energy stored in the charged battery pack 32 to propel the vehicle using mechanical power generated by the electric motor 20. When the battery pack 32 is drained fully or partially to a certain level, the hybrid vehicle 10 is switched to propel using mechanical power generated by the internal combustion engine 24 running on fuel stored in the primary fuel tank 40. When the primary fuel tank 40 is emptied, the internal combustion engine 24 can keep on running by opening a valve 48 fitted to the fuel line 52 leading from the battery pack 32 to the engine 24, thus directing the liquid coolant, which is suitable as fuel, to run the internal combustion engine.

It will be understood that to the same extent the primary fuel tank 40 capacity can be used first to run the engine 24 and the battery pack 32 energy used later to power the electric motor 20, or they can be intermittently switched there between, or both operated together as needed for efficient propelling of the hybrid vehicle and as known in the art.

The preferred type of hybrid vehicle according to the present invention, is the parallel type in which the electric motor and the internal combustion engine are mechanically coupled such that they can drive the vehicle transmission either individually or together. However, the series type of hybrid vehicles, in which only the electric motor propels the vehicle, may also use the proposed range extending system according to the present invention to extend the operational time of an electric generator powered by the internal combustion engine.

According to another aspect of the present invention, it is possible to use the battery pack to store energy generated by regenerative braking and further use the battery as energy source even after all or part of the original liquid coolant is used as fuel. One option to facilitate such regenerative braking and use of battery without the original liquid coolant, is by completely pump draining the content of the battery pack coolant loop 16 into the primary fuel tank 40 by opening valve 46 fitted on fuel line 56 connecting the battery pack 32 and primary fuel tank 40. Following by filling the battery pack 32 coolant loop 16 with a different available liquid such as water. Typically water has more availability than fuel, it does not have to be carried on with the vehicle but collected and stored occasionally when available.

Another option to cool the battery pack after the liquid coolant is consumed, is by air cooling. With reference to Fig. 2, there is shown a battery pack generally referenced 12, with option to fully or partially remove the top panel 60 and part of the side panels 62 to allow free or forced air flow path within the battery pack (demonstrated with arrows) using the same air moving fan 44 fitted to the heat exchanger 36. The air cooling system can alternately use compressed refrigeration gas that expands or evaporates in the cooling space 26 of the battery pack 32.

A third option provides sufficient cooling of the battery pack even when the liquid coolant is emptied to a certain level, for example by circulating the coolant faster in the coolant loop 16 to overcome the missing volume of liquid coolant.

Optionally, as shown in Fig. 3, demonstrating a battery pack generally referenced 14, a relatively small volume of remaining liquid coolant can be spread into the battery pack by a plurality of nozzles 64 fitted to a top wall of the battery pack, thus wetting the hot surfaces of the battery cells 22 with cooled liquid coolant returning from the heat exchanger 36. With reference to Fig. 3, the circulating pump 42 is fitted on the return line 68 from the heat exchanger 36 to the battery pack 32 thus providing pressure to the distribution pipe 66 carrying the nozzles.

Alternatively, a variable speed or variable displacement circulation pump 42 can be used to elevate the pressure on the return line 68 and pressure spray the liquid coolant through high pressure nozzles 64 for higher impact and better heat transfer between the liquid coolant and the battery cells 22 hot surfaces.

Although any type of fuel may be used as a liquid coolant for the purpose of the present invention, the preferred fuel is a diesel fuel and the preferred internal combustion engine is a diesel engine. Depending on the type of battery pack 32 and the internal electrical insulation, if electric charged components of the battery cells 22 are in direct contact with the liquid coolant then a diesel fuel pure of electric conductivity enhancement additives would be preferred. Optionally a mineral oil can be used as a liquid coolant and fuel, in such case, the mineral oil can be mixed with diesel oil taken from the primary fuel tank 40 of the vehicle, prior to being used as a fuel for the internal combustion engine 24. Mixing can be performed by simultaneously opening valve 50 at the exit from the primary fuel tank 40 and valve 48 leading from the battery pack 32, both feeding pipe 54 which is leading to the engine 24. Preferably the valves 48, 50 are metering valves which enable a precise mixing rate as electrically signaled by the power management controller 34.

In cases where the battery pack 32 is completely emptied of liquid coolant and air cooling is not provided, regenerative braking may be disabled or limited by temperature control to prevent overheating of the battery pack during regenerative braking recharge.

The present invention seeks protection to the system as described above as well as the method steps taken to accomplish the desired result of extending the drive range or time of operation of a hybrid vehicle. Accordingly a method is provided comprising one or more of the steps below:

a. providing a liquid cooled battery pack 32,

b. filling the battery pack 32 coolant loop 16 with a liquid coolant usable as an internal combustion engine fuel,

c. charging the battery pack 32,

d. propelling the hybrid vehicle 10 by the electric motor 20 energized from the battery pack 32,

e. monitoring the battery pack 32 energy level,

f. detecting certain predetermined energy drain level of the battery pack 32,

g. propelling the hybrid vehicle 10 by the internal combustion engine 24 running on the fuel taken out of the primary fuel tank 40,

h. propelling the hybrid vehicle 10 by the internal combustion engine 24 running on the liquid coolant taken out of the battery pack coolant loop 16.

Optionally an additional method step is provided:

i. filling the battery pack coolant loop 16 with other liquid such as water.

Or alternately:

j . cooling the battery pack with air.

Or alternately:

k. cooling said battery pack with compressed refrigeration gas.

The sequence of some of the steps described above may be interchanged, yet accomplishing the desired result of extending the drive range of a hybrid vehicle. It will be understood that all optional sequences of all or part of the above method steps are falling under the scope of the present invention.

It will be appreciated that the specific embodiments of the present invention described above and illustrated in the accompanying drawings are set forth merely for purposes of example. Other variations, modifications, and applications of the present invention will readily occur to those skilled in the art. It is therefore clarified that all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.

Claims

CLAIMS:

1. A range extending system for a hybrid vehicle, comprising: a liquid cooled battery pack and a liquid coolant; wherein said liquid coolant is suitable as an internal combustion engine fuel, and wherein said hybrid vehicle can use said liquid coolant to run an internal combustion engine.

2. A range extending system as claimed in claim 1, wherein said hybrid vehicle is of the parallel type.

3. A range extending system as claimed in claim 1, wherein said liquid coolant is used to run said internal combustion engine after said battery pack is drained of electric power.

4. A range extending system as claimed in claim 1, wherein said liquid coolant is replaced with different liquid after said liquid coolant is used to run said internal combustion engine.

5. A range extending system as claimed in claim 4, wherein said liquid coolant is pumped into a primary fuel tank of said hybrid vehicle prior to being replaced with said different liquid.

6. A range extending system as claimed in claim 1, wherein said battery pack is gas cooled after said liquid coolant is emptied and wherein said gas is selected between air and compressed refrigeration gas.

7. A range extending system as claimed in claim 1, wherein said liquid coolant provides sufficient cooling of said battery pack even when emptied to a certain level.

8. A range extending system as claimed in claim 7, wherein said liquid coolant is circulated faster to enable sufficient level of cooling.

9. A range extending system as claimed in claim 7, wherein said liquid coolant is spread into said battery pack by a plurality of nozzles fitted to a top wall of said battery pack.

10. A range extending system as claimed in claim 7, wherein said liquid coolant pressure is elevated on a return line and said liquid coolant is pressure sprayed into said battery pack.

11. A range extending system as claimed in claim 1, wherein said liquid coolant is a diesel fuel.

12. A range extending system as claimed in claim 2, wherein said diesel fuel is pure of electric conductivity enhancement additives.

13. A range extending system as claimed in claim 1, wherein said liquid coolant is a mineral oil.

14. A range extending system as claimed in claim 13, wherein said mineral oil is mixed with a diesel oil taken from a primary fuel tank of said vehicle, prior to being used as a fuel for said internal combustion engine.

15. A range extending system as claimed in claim 1, wherein regenerative braking is limited while said liquid coolant is used to power said internal combustion engine.

16. A method for extending the range of a hybrid vehicle comprising the steps of:

a) providing a liquid cooled battery pack;

b) filling said battery pack coolant loop with a liquid coolant usable as an internal combustion engine fuel; and

c) propelling said hybrid vehicle by an internal combustion engine running on said liquid coolant taken out of said battery pack coolant loop.

17. The method as claimed in claim 16, further comprising after step b and before step c, the steps of:

d) charging said battery pack;

e) propelling said hybrid vehicle by an electric motor energized from said battery pack;

f) monitoring said battery pack energy level; and

g) detecting certain predetermined energy drain level of said battery pack.

18. The method as claimed in claim 16, further comprising the step of:

h) filling said battery pack coolant loop with other liquid.

19. The method as claimed in claim 16, further comprising the step of:

i) cooling said battery pack with air.

20. The method as claimed in claim 16, further comprising the step of:

j) cooling said battery pack with compressed refrigeration gas.