, Description:Proton Exchange Membrane Fuel cell system for small electric vehicles.
FIELD OF INVENTION
[001] The present invention generally relates to operation of battery operated electric vehicle wherein the vehicle is powered with DC /AC electric motor with its on board controller to fulfil the dual function for controlling the speed of the motor and to convert the DC power (Battery source) to AC or DC as required for motor. In case of pure battery electric vehicle, the source of DC power is supplied from battery pack to the motor controller, whereas in case of hybrid configuration DC power is supplied to motor controller from fuel cell system placed under the passenger’s cabin space. The output from the fuel cell system is DC power and its voltage is slightly higher than that of the on-board battery power pack voltage. The invention involves integration of various subsystems like hydrogen supply, air supply, humidifiers, cooling, main power convertor, auxiliary power convertor, gas-liquid separation, main controller, air blower controller which are to be integrated to form fuel cell system whose final dimensions are constrained by the available space under the passenger seat of small electric vehicles like golf carts as a single unit for supply of uninterrupted DC power to the electric motor.

[002] This invention is in particular directed to proton exchange membrane fuel cell system for small electric vehicles.

BACKGROUND/PRIOR ART OF THE INVENTION

[003] Reference may be made to the following prior arts.

[004] DE 3339 890 C2 invention relates to an energy supply network for an electric car, powered by a fuel cell or by a battery. A vehicle having an energy supply system of this generic type is disclosed wherein the device, a connection of the battery as well as a connection of one of the current-consuming elements fed by the battery, and therefore one of the two load current circuit lines, is connected to the potential of the vehicle body.

[005] US 5,641,031 relates to fuel-cell-powered electric vehicle disclosed the type not having any electrical energy Storage. According to this invention, fuel tank constituting the fuel cell System are installed within the loading compartment in the rear region of the vehicle.

[006] In the proposed application, a fuel cell system is developed and demonstrated using conventional electric golf cart. A readily available electric Golf Cart having a DC motor with an in-built controller is used for demonstration of fuel cell hybrid electric vehicle.

[007] The existing in-house developed PEM Fuel Cell system is modified such that the final dimensions of the fuel cell system with its necessary balance of plant items including Control & Instrumentation subsystems are mounted to a supporting frame and its final dimensions are significantly less than that of the cabin space dimensions available under the passenger’s seat. The modified hybrid electric golf cart is tested and under normal operating conditions the vehicle is powered by fuel cell system. Whereas, under high torque or sudden acceleration situations when load on motor exceeds the set value it operates in combination with battery & fuel cell.

[008] During demonstration, the Golf –Cart is modified for retrofitting on board Hydrogen storage of 5 kWh equivalent electric

power with cascade of lightweight aluminium cylinders. Also, the vehicle is provided with an integrated on-board safety system to shut down in case of malfunction and emergency. The hybrid electric golf cart vehicle has been tested successfully for demonstration of technology with pay load of 300 kg up to maximum speed of 20 KMPH.
OBJECTS OF THE INVENTION
[009] The object of the invention is to provide Proton Exchange Membrane Fuel cell system for small electric vehicles.

[010] Another object of the invention is to propose Proton Exchange Membrane Fuel cell system for small electric vehicles which is simple in construction.

[011] Still another object of the present invention is to provide Proton Exchange Membrane Fuel cell system for small electric vehicles which is efficient.

[012] Further object of the present invention is to provide Proton Exchange Membrane Fuel cell system for small electric vehicles which is easily fitted in the passenger’s cabin space of small electric vehicles.

[013] These and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present invention is illustrated.

SUMMARY OF THE INVENTION
[014] One or more drawbacks of conventional systems and process are overcome, and additional advantages are provided through the apparatus and a method as claimed in the present disclosure. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be part of the claimed disclosure.

[015] According to this invention, there is provided proton exchange membrane fuel cell system for small electric vehicles comprising a fuel cell stack provided with inlet ports for supply of Hydrogen and air inside the fuel cell stack for reaction, wherein the cell stack is provided with an outlet port and outlet ports for exit of unconverted Hydrogen and air respectively, wherein the inlet ports, each of which is in communication with a humidifier in flow communication with water pump outlet in fluid communication with water reservoir.

[016] The outlet port for Hydrogen is placed diagonal to the stack hydrogen inlet port and the outlet ports are placed in right angle to each other, in which the bottom exit is used for draining of excessive liquid water carried by air and the other air exit is used as the main air exhaust, in which the size of port is higher than the size of bottom air exit port.

[017] The fuel cell stack, each cell of which receives hydrogen of anode side through inlet port which is in communication with hydrogen humidifier where in hydrogen gains water in the humidifier while exiting from the humidifier, wherein it receives the dry hydrogen from external supply source using a solenoid valve which is in communication with pressure regulator using which hydrogen pressure in the stack is maintained at required value.

[018] The cells of cathode side stack receive air into the stack through air inlet which is in communication with the humidifier similar to the humidifier used at anode side which is placed in between stack air inlet and cathode air blower using which the air is fed into the stack, in which the rate of air flow is controlled using an exclusive controller which uses a power source of 24 VDC and a signal of 0-5 VDC to change the speed of the blower.

[019] The saturated water and air are separated within the reservoir and wherein air and water separated and any excess water are carried away by air through outlet provided for the reservoir and inlet to the reservoir is in communication with the air exit to receive saturated air from which the water is separated and partially saturated air is allowed to pass through outlet provided to the reservoir to the ambient.

[020] The hydrogen is allowed to pass through the exit which is in communication with the another solenoid valve, in which one side of the valve is in communication with hydrogen exit port and other side is in communication with the tube through which the hydrogen is being vent facing towards vertical to the vehicle whose exit is maintained above the height of the fuel cell system placement in the vehicle, wherein fuel cell stack is enclosed between bottom and top jackets using the clamps and tie rods from four sides.

[021] The fuel cell stack is cooled by forced air circulation through the stack by a cooling air blower mounted adjacent to the fuel cell stack whose outlet is in communication with the bottom duct mounted below the stack to receive the cooling air to cool the stack and the stack is provided with top duct to receive the hot air from the stack, in which both ducts are mounted to stack opposite to each other, wherein the hot air received by the top duct is provided to pass through the two exhaust routing duct whose flow area is higher than the area of cooling blower outlet area and they both are aligned in 90° to each other.

[022] Few additional blocks are mounted over the frame with support structures including control subsystem which is mounted at upper side of the frame, and battery bank and power convertor subsystem are mounted at bottom part of the frame over the perforated metal screen secured to bottom side of the frame.

[023] The fuel cell stack rests on the frame structure and is in communication with the Hydrogen supply subsystem which receives hydrogen from any external source having pressure range from 1-5 bar which is being humidified using a humidifier assembled inline between the fuel cell stack hydrogen inlet port and line hydrogen pressure regulator which is in communication with the first solenoid valve outlet.

[024] Said fuel cell stack unit is in communication with the air supply subsystem which receives air from air blower outlet with pressure range from 10 mbar- 500 mbar which is humidified using said humidifier assembled inline between the fuel cell stack air inlet port and air blower outlet.

[025] The gas-liquid separator tank is mounted under the fuel cell stack and is in communication with the air outlet wherein the water carried by the air is being separated in the gas liquid separator tank. Bottom of the tank is in communication with the water pump inlet which is mounted on the frame at lower side adjacent to stack and also the outlet of the pump is in communication with both the humidifiers used on air and hydrogen side respectively.

[026] The two humidifiers are similar to membrane humidifiers in terms of construction being assembled inline of individual gases of hydrogen and air, wherein the shell side of both the humidifiers are provided with direct communication to circulate the water from one humidifier to the other and they are separated as individual in respect of tube side through which gas is allowed to flow.

[027] There is provision of auxiliary power convertor whose output is used for supply of internal power requirements and main power convertor is used for supply of external electrical applications, both of which are in electrical communication with the fuel cell stack terminals of positive and negative of the power convertor input terminals of positive and negative and whose output voltages are independent to each other and they are mounted at bottom side of the frame over the perforated mesh.

[028] Perforated mesh is mounted at bottom side of the frame to hold the various components like main power convertor, auxiliary power converter, start-up batteries, gas-liquid separator and cooling blower.

[029] A main controller is mounted at top side of the frame located adjacent to fuel cell stack, between the air and hydrogen supply subsystems which is powered using auxiliary power supplies of 24 VDC followed by the start-up batteries initially.

[030] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

[031] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.

[032] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[033] The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and processes that are consistent with the subject matter as claimed herein, wherein: -

Figure 1: proton exchange membrane fuel cell stack with input & output communication ports of present invention.

Figure 2: Left side view of Fuel cell system with its sub-systems according to present invention.
Figure 3: Right side view of Fuel cell system with its sub-systems in accordance with the present invention.

Figure 4: Top view of the perforated sheet of present invention.

[034] The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAIL DESCRIPTION OF THE PRESENT INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS OF PREFERRED EMBODIMENTS

[035] While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.

[036] The present invention makes a disclosure regarding a technology pertaining to Proton Exchange Membrane Fuel cell system for small electric vehicles.

[037] Fuel cell is an electrochemical device which converts chemical energy to electrical energy as the fuel (H2) and oxygen are supplied. Like battery power packs, fuel cell also comprises of multiple number of such cells which are connected in series to obtain more voltage and such number of multiple cells are assembled between two end plates (1) followed by current collectors (2) is called a fuel cell stack (3) which is a power block. According to the invention, the reactant gases of hydrogen and air are fed at the respective inlet ports (4) and (5) and they are reacted inside the stack and remaining unconverted gases are allowed outside the stack through the ports placed diagonal to the stack hydrogen inlet port (4) for hydrogen exit through (6) and air is allowed to exit through two ports (7a) and (7b) which are in right angle to each other. Among two exits provided for air, the bottom exit (7b) is used for draining of excessive liquid water carried by air and the other air exit (7a) is used as the main air exhaust. The size of port (7a) is higher than the size of bottom air exit port (7b).

[038] Every cell in the fuel cell stack (3) receives hydrogen of anode side through inlet port (4) which is in communication with hydrogen humidifier (8) where in hydrogen gains water in the humidifier while exiting from the humidifier (8), wherein it receives the dry hydrogen from external supply (9) source using a solenoid valve (10) which is in communication with pressure regulator (11) using which hydrogen pressure in the stack is maintained at required value. Also, all cells of cathode side stack (3) receive air into the stack through air inlet (5) which is in communication with the humidifier similar to the humidifier (8) used at anode side which is placed in between stack air inlet and cathode air blower (12) using which the air is fed into the stack. The rate of air flow is controlled using an exclusive controller (13) which uses a power source of 24 VDC and a signal of 0-5 VDC to change the speed of the blower.

[039] Performance of fuel cell can be improved provided the reactant gases of hydrogen and air are being humidified while they are fed through the humidifiers (8). The water required for humidification of the reactants is being fed into the humidifier (8) using a water pump (14) whose outlet is in fluid communication with the both humidifiers used for air and hydrogen. Also, the water pump (14) is in fluid communication with water reservoir (15) wherein the saturated water and air would be separated within the reservoir (15) and wherein air and water separated and any excess water would be carried away by air through outlet (16) provided for the reservoir and inlet to the reservoir is in communication with the air exit (7) to receive saturated air from which the water is separated and partially saturated air is allowed to pass through outlet (16) provided to the reservoir (15) to the ambient.
[040] On the other side, hydrogen is allowed to pass through the exit (6) which is in communication with the another solenoid valve (17) which is similar to the one used for Hydrogen inlet but different in operation. one side of the valve (17) is in communication with hydrogen exit port (6) and other side is in communication with the tube through which the hydrogen is being vent facing towards vertical to the vehicle whose exit is maintained above the height of the fuel cell system placement in the vehicle.

[041] Fuel cell stack (3) is enclosed between bottom (18) and top jackets (19) using the clamps (20) and tie rods (21) from four sides. One side of the bottom jacket is provided with a duct (22) opened and other side is a dead end and the internal size of duct is little larger than the size of centrifugal air blower (23) exit (24). They are to be connected like a male-female plug arrangement for its integration with the bottom jacket rectangular duct (22). Beside this, the top jacket is provided with two ducts (25) whose length is extended to project the duct outside the fuel cell power pack in which all the subsystems are mounted over the supporting frame (26). Apart from the above components few additional blocks are also mounted over the frame with some support structures such as control subsystem (27) which is mounted at upper side of the frame (26), and battery bank (28) and power convertor subsystem (29) are mounted at bottom part of the frame over the perforated metal

screen (30) screwed to bottom side of the frame to provide mechanical support, ease of integration and better access to maximum subsystems in case of maintenance if required. All the subsystems and required components which are necessary to form fuel cell power as aforesaid are completely integrated within the frame (26) and whose dimensions are significantly less than that of cabin space dimensions available under the passenger’s seat.

Features of Present Invention
- A proton exchange membrane fuel cell system of its final geometry is limited by the supporting frame and its geometry is less or similar to that of geometry available under the passenger’s seat cabin and the size of fuel cell power pack in terms of its length, breadth and height dimensions are smaller in size than the cabin space dimensions in the battery electric vehicle.

- The dimensions of the complete fuel cell power pack comprises of fuel cell stack and other subsystems like reactants supply, humidification, water regeneration & recirculation, leak detection sensors & other instrumentations, control subsystem, auxiliary power convertors and main power convertor which produces the voltage higher than the on board battery pack voltage are to be assembled within the single enclosure of fuel cell power pack whose dimensions are lower than the passenger seating cabin space dimensions.

- The PEM Fuel cell stack is cooled using the ambient air received into the passengers seating cabin space from vehicle surroundings, wherein the assembled stack is enclosed between the bottom and top jackets whose length is less than

the stack length. The bottom part of the jacket is provided with duct and the top jacket is provided with two or more exhaust ducts if required. The alignment of bottom jacket and top jacket ducts are in right angle to each other.

- The bottom part of the jacket mouth is similar to the geometry of centrifugal blower outlet of geometry and top jacket vents are provided with two extended ducts for integration to any common manifold to expel the hot air coming out from the stack while the system is in operation.

- The sub systems of start-up battery, power convertors, water reservoir and cooling air blower are mounted to the perforated screen which is screwed to the bottom of the frame for ease of maintenance or replacement of afore said subsystems.

- All other sub-systems including stack are mounted to over the frame or with the assistance of supports welded or bolted to the basic frame in which all the sub-systems are assembled to form complete fuel cell system, whose final dimensions are limited and its sizes are lower than the passengers cabin space.

[042] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.

[043] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.

[044] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particulars claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances, where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B”.
[045] The above description does not provide specific details of manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from

those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art are capable of choosing suitable manufacturing and design details.

[046] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.

[047] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.

[048] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Claims:Proton exchange membrane fuel cell system for small electric vehicles comprising a fuel cell stack (3) provided with inlet ports (4 and 5) for supply of Hydrogen (H2) and air (O2) inside the fuel cell stack (3) for reaction, wherein the cell stack (3) is provided with an outlet port (6) and outlet ports (7a and 7b) for exit of unconverted Hydrogen and air respectively, wherein the inlet ports (4 and 5), each of which is in communication with a humidifier (8) in flow communication with water pump (14) outlet in fluid communication with water reservoir (15).

2. Proton exchange membrane fuel cell system for small electric vehicles as claimed in claim 1, wherein the outlet port (6) for Hydrogen is placed diagonal to the stack hydrogen inlet port (4) and the outlet ports (7a and 7b) are placed in right angle to each other, in which the bottom exit (7b) is used for draining of excessive liquid water carried by air and the other air exit (7a) is used as the main air exhaust, in which the size of port (7a) is higher than the size of bottom air exit port (7b).

3. Proton exchange membrane fuel cell system for small electric vehicles as claimed in claim 1 or 2, wherein the fuel cell stack (3), each cell of which receives hydrogen of anode side through inlet port (4) which is in communication with hydrogen humidifier (8) where in hydrogen gains water in the humidifier while exiting from the humidifier (8), wherein it receives the dry hydrogen from external supply (9) source using a solenoid valve (10) which is in communication with pressure regulator (11) using which hydrogen pressure in the stack is maintained at required value.

4. Proton exchange membrane fuel cell system for small electric vehicles as claimed in claim 1-3, wherein the cells of cathode side stack (3) receive air into the stack through air inlet (5) which is in communication with the humidifier similar to the humidifier (8) used at anode side which is placed in between stack air inlet and cathode air blower (12) using which the air is fed into the stack, in which the rate of air flow is controlled using an exclusive controller (13) which uses a power source of 24 VDC and a signal of 0-5 VDC to change the speed of the blower.

5. Proton exchange membrane fuel cell system for small electric vehicles as claimed in claim 1-4, wherein the saturated water and air are separated within the reservoir (15) and wherein air and water separated and any excess water are carried away by air through outlet (16) provided for the reservoir and inlet to the reservoir is in communication with the air exit (7) to receive saturated air from which the water is separated and partially saturated air is allowed to pass through outlet (16) provided to the reservoir (15) to the ambient.

6. Proton exchange membrane fuel cell system for small electric vehicles as claimed in claim 1-5, wherein the hydrogen is allowed to pass through the exit (6) which is in communication with the another solenoid valve (17), in which one side of the valve (17) is in communication with hydrogen exit port (6) and other side is in communication with the tube through which the hydrogen is being vent facing towards vertical to the vehicle whose exit is maintained above the height of the fuel cell system placement in the vehicle, wherein fuel cell stack (3) is enclosed between bottom (18) and top jackets (19) using the clamps (20) and tie rods (21) from four sides.

7. Proton exchange membrane fuel cell system for small electric vehicles as claimed in claim 1-6, wherein the fuel cell stack (3) is cooled by forced air circulation through the stack (3) by a cooling air blower mounted adjacent to the fuel cell stack (3) whose outlet is in communication with the bottom duct (22) mounted below the stack to receive the cooling air to cool the stack and the stack is provided with top duct (25) to receive the hot air from the stack, in which both ducts are mounted to stack opposite to each other, wherein the hot air received by the top duct is provided to pass through the two exhaust routing duct whose flow area is higher than the area of cooling blower outlet area and they both are aligned in 90° to each other.

8. Proton exchange membrane fuel cell system for small electric vehicles as claimed in claim 1-7, wherein few additional blocks are mounted over the frame with support structures including control subsystem (27) which is mounted at upper side of the frame (26), and battery bank (28) and power convertor subsystem (29) are mounted at bottom part of the frame over the perforated metal screen (30) secured to bottom side of the frame.

9. Proton exchange membrane fuel cell system for small electric vehicles as claimed in claim 1-8, wherein the fuel cell stack rests on the frame structure and is in communication with the Hydrogen supply subsystem which receives hydrogen from any external source having pressure range from 1-5 bar which is being humidified using a humidifier (8) assembled inline between the fuel cell stack hydrogen inlet port and line hydrogen pressure regulator which is in communication with the first solenoid valve outlet.

10. Proton exchange membrane fuel cell system for small electric vehicles as claimed in claim 1-9, wherein said fuel cell stack unit (3) is in communication with the air supply subsystem which receives air from air blower outlet with pressure range from 10 mbar- 500 mbar which is humidified using said humidifier (8) assembled inline between the fuel cell stack air inlet port and air blower outlet.