FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION
A SYSTEM AND METHOD FOR CHECKING LEAKAGE OF HEATER
CIRCUIT OF HVAC SYSTEM
2. APPLICANT
MAHINDRA & MAHINDRA LIMITED
GATEWAY BUILDING, APOLLO BUNDER, MUMBAI - 400001.
AN INDIAN COMPANY.
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION:
The present invention relates to a system and method for testing functioning of a fluid flow control valve such as direction control valve or one way valve or alike when it is used with closed loop hydraulic system and for checking leakages of the hydraulic circuit in applications such as HVAC (Heating Ventilation and Air-Conditioning) system, and more particularly, to a visual indication device for checking whether the control valve is functioning as desired for the required performance and if any undesirable leakage is present in the heater circuit involving fluid flow.
BACKGROUND OF THE INVENTION:
A HVAC system generally comprises a heater system and an air conditioning system, which are operatively combined together as a single system for providing desired conditioned environment to an enclosed area. Practically, both air conditioning system and heating system do not work simultaneously. In this case, any one of the systems needs to be shut down to operate another system otherwise it may not provide desired conditioned environment. The air conditioning system has its own accessories such as evaporator, blower(s) and fluid conduit for air circulation provided with inlet and outlet; and the heater system comprises a heater core, one way direction control valve and fluid conduit for circulating hot fluid therethrough. In kind of applications where both air conditioning system and heater system are provided as a single combined system, separate switches have to be provided for selectively operating both systems as per the need.
One of the main fields of application of a HVAC system is automotive vehicle, wherein entire system is packed in compact size within the

available enclosed space of vehicle because of space-availability constraints. In some applications like off road vehicles, the entire system is positioned in the cabin roof thereby to give conditioned environment to the operator inside the cabin as per operator's requirement. The main concern here is, due to compact packaging of HVAC system, the evaporator and heater core are placed very near to each other. When there is any malfunction/ fault with any of these systems/ sub-systems, it may directly affect another system and cause deficiency in performance of the HVAC system. Hence, it is very essential to ensure proper sealed and leak-free assembly of both air conditioning system and heater system.
In general, for applications of HVAC system, air conditioning system works as default system and heater system works as an add on to the entire HVAC system. So when there is a need, based on environmental condition, to operate heater system, the operator has to selectively operate the switch mode. The ideal operating mode of a heater system in aforementioned application is when the switch provided on the control panel is turned ON, the control valve provided on the first fluid conduit opens and allows engine coolant, that is carrying some amount of heat generated due to engine operation, to heater core. The heater core extracts heat from the hot coolant and uses for conditioning the air inside the cabin. Then the coolant returns to engine crankcase/block through second fluid conduit. When the switch is turned OFF, the control valve restricts the flow from flowing to heater core. The problem here is once the entire HVAC system is assembled onto the vehicle, it is very difficult to identify the problem if there is any deficiency in the performance of HVAC system and, further, dismantling the entire system from vehicle becomes a cumbersome process. There have been lots of inventions

developed in the field of leakage test for performing the leakage test, some of which are given below:
US Patent 5461903 discloses an apparatus and method for detecting leak in a closed, fluid transfer system, specifically a hydraulic system, by comparing the actual rate of fluid level change in the fluid reservoir to the rate of fluid level change computed from the rate of flow and capacity of the system wherein an actual rate of level change in excess of the computed change indicates leakage from the system. An apparatus for determining direction of flow through a conduit and method using the apparatus in which a magnet on a piston slidably engages inside a valve body is caused to move thereby causing a variance in a measured inductance indicating the direction the piston has moved. Another US patent 7210338 discloses a valve testing device and method for determining whether a fluid control valve is operating acceptably by passing pressurized fluid through the valve and to a flow measuring means where the flow rate of fluid through the valve can be measured. Yet another US Patent 4119016 discloses a hydraulic device which detects leaks in the working by monitoring the level of hydraulic fluid in the reservoir. Yet another US Patent 5187973 discloses a drive system which determines the leak in the conduit by measuring the pressure difference available in the conduit.
However, the need remained to develop a system and method for HVAC system to ensure, with help of a visual indication device, leakage free functioning of heater system assemblies and proper functioning of control valve so as to have efficient performance of air conditioning system and such confidence before mounting the system onto the vehicle.

OBJECTIVE OF THE INVENTION:
The present invention overcomes the shortcomings associated with the background art and achieves other advantages not realized by the background art.
Main object of the present invention is to provide a system and method for checking functioning of a fluid flow control valve incorporated with the heater system assembly used with a HVAC system and for testing any fluid leakage from the system.
Another object of the present invention is to provide a system and method for performing the testing operation of heater system incorporated with the HVAC system before assembling the HVAC system onto the vehicles.
Yet another object of the present invention is to provide a system and method for checking whether the control valve fluidly coupled with the first fluid conduit maintains its normal position, that is, fully closed condition, after assembly with the heater system.
Yet another object of the present invention is to provide a system and method thereby to minimize inconvenience and time wasted in resolving problem(s) of heater system that would otherwise surface after assembling the system onto the vehicle thereby causing more inconvenience and wastage of more time dissembling the system and identifying and resolving these problems.

In accordance with one aspect of the present invention, the system and method for checking effective functioning of a fluid flow control valve fluidly coupled with the heater system and leakage thereof in a HVAC application comprises a visual indication device, a transparent tube for fluidly coupling with a second port of said visual indication device, a first conduit and a second conduit for fluidly communicating with said visual indication device with the heater system,
wherein
said visual indication device comprises a motor-pump unit, a reservoir, a
controller,a pressure sensor, a fluid level sensor, a display board and a
timer.
The method of checking effective functioning of the fluid flow control vaJve and leakage of heater system according to the present invention is as follows:
After connecting the visual indication device to electrical power source, check for fluid level position in the reservoir, which will be indicated in the display board with the help of the fluid level sensor and the controller. If the fluid level is below the predetermined position, fill the reservoir with the fluid and then start the motor-pump unit to pump the fluid to the heater system via the first conduit. If the control valve is in fully closed condition, then the flow of fluid will be restricted from flowing to the heater core and subsequently, pressure in the conduit will get increased. When the pressure is reached up to 2bar, the pressure sensor will give signal to the controller and timer for shutting down the motor-pump unit after 3 seconds. If there is no flow of fluid observed in the transparent tube then the heater system is said to be functioning effectively and if any flow observed in the transparent tube then the system is said to be

functioning in undesired manner. In such case, the entire heater system can be checked for any leakage through the control valve and/or conduits joints and the testing may be repeated tiff the heater system functions properly.
In another aspect of the present invention, the system may be provided with a variable frequency drive, a fluid flow sensor, a display and a variable switch for varying the fluid flow which pass through the heater system as per the requirement.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, whife indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS:
The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: FIG. 1 is schematic representation of heater system inside the cabin roof
of vehicle and connected inlet & outlet thereof with visual indication
device; FIG. 2 is schematic representation of electrical circuit illustrating
operation of visual indication device in accordance with present
invention; and FIG. 3 is block diagram illustrating the method of operation of the system
according to present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT:
The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its applications or uses.
An exemplary embodiment of a visual indication device 17 and working method thereof according to the present invention is illustrated with referring to FIG. 1-3. The visual indication device 17 is securely mounted on a workbench or any other movable test stand for taking the device to desired place. Referring to FIG.l,a tractor cabin roof 10 is mounted with a heater system (shown in schematic representation) which is connected to the visual indication device 17 via a first conduit 14 and a second conduit 15 which serve as outlet fluid flow path line and inlet fluid flow

path line of the visual indication device 17 respectively. The conduits may be in the form of a pipe structure or flexible hose type.
A fluid flow control valve 13, preferably a fluid flow direction control valve is fluidly coupled with second end of the first conduit 14 and first end of a third conduit 18. First end of the first conduit 14 is fluidly coupled with a first port of the visual indication device 17 and second end of the third conduit 18 is fluidly coupled inlet port of a heater core 11 for fluidly communicating the fluid from the visual indication device 17 with control valve 13 and then with the heater core 11. A second port of the visual indication device 17 is fluidly coupled with a short transparent tube 16 which in turn further fluidly coupled with first end of the second conduit 15 and second end thereof is coupled with outlet port of heater core 11. The control valve 13 is mechanically actuated by a control switch 12 which is located inside the cabin 10. When the control switch 12 is positioned at OFF condition, the control valve maintain its normal position that is fully closed condition and when the switch is actuated, the control vaive fully open and allows the visual indication device 17 to fluidly communicate with the heater core 11. When the control valve 13 is in completely closed condition, the fluid contained in a reservoir (not shown) that is present in the visual indication device 17 is restricted from passing through the control valve 13 to the heater core 11. The fluid may be engine cooling water, which carry some amount of heat generated from engine operation.
During testing of heater system assembly, a source of electrical energy is connected to the visual indication device 17 in order to pump the pressurized fluid from the reservoir. The control switch 12 inside the cabin 10 is operated manually which in turn further actuates the control

valve 13 through a mechanically controlled link means. It should be noted that any improper assembly of control valve 13 and mechanically controlled link means will make the control valve 13 operate in undesired condition i.e. the control valve will not close properly. When the control valve 13 is in fully opened condition, the fluid contained in the reservoir flows into the heater core 11 through the first conduit 14, the control valve 13 and the third conduit 18 and return back to the reservoir through the second conduit 15. All fluid couplings of the heater system may be checked for any leakages. If any leakage is found, the visual indication device 17 is switched OFF manually and the entire assembly of heater system and control valve 13 is checked.
When the control valve 13 is in completely closed condition, the pressure builds up in the first conduit 14 and when the pressure reaches to predetermined value, say 2 bar according to present invention, the Pump-motor setup is switched OFF automatically by a timer delay after certain period of time that is 3 seconds according to the present invention. This ensures that the valve is in completely closed position as desired, by way of no fluid flow in the transparent tube 16. If there is no pressure build up in the first conduit 14 or there is a little flow in the transparent tube 16 then the valve is said to be malfunctioning and it is advisable to replace the control valve 13 or check the assembly of the heater system assemblies.
Referring to FIG. 2, the operation of the visual indication device 17 is as follows: initially the level of the fluid in the reservoir is checked by a fluid level sensor 4 and if the level of the fluid is as per predetermined level then the sensor 4 gives signal to a controller 3. When the fluid level is above predetermined level, then only the visual indication device 17 is to

be operated. A start-Push Button 8 is used for starting the operation of the visual indication device 17. The circuit is completed through the path of main supply, the controller 3, start Push Button 8, a stop Push Button 9, a timer 6 and a contactor coil 7. As the contactor coil 7 is energized, the main power supply goes to motor-pump unit 1 and energize said motor-pump unit 1 to pump the fluid present in the reservoir to flow through the first conduit 14. When the control valve 13 is closed, the fluid pressure in the first conduit 14 is increased. When the pressure in the first conduit 14 reaches to 2 bar, it gets sensed by a pressure sensor 5 and gives signal to the timer 6. Said timer actuates the controller 3 after a preset period of time that is 3 seconds thereby to switch off the motor-pump unit 1 automatically. The motor-pump unit 1 can also be switched off at any time with the help of stop Push Button 9. In case the fluid level comes down below the predetermined level during the testing operation, the motor-pump unit 1 will automatically turned off, and subsequently it will be indicated in the display board with the help of controller 3. Again the operation can be started after filling the reservoir with the fluid. Miniature Circuit Breaker 2 is used to have overload protection of circuit and motor-pump unit 1.
In another aspect of the present invention, with referring to FIG. 2, the visual Indication device 17 is provided with a variable frequency drive 20 for establishing variable flow within the heater system as the water pump of engine performs when the heater system is mounted onto the vehicle. Said variable frequency drive 20 is configured with a sensor for sensing the flow rate of fluid in the heater system and thereafter for sending the signal to a display 22 for indicating the flow rate. The variable frequency drive 20 is also configured with a switch 19 for varying the flow rate of the fluid flowing through the heater system as per the requirement.

The method of testing operation is illustrated with reference to FIG.3. The reservoir in the visual indication device 17 should be filled with fluid before starting the operation for testing the heater system; level of which is indicated in the display board with the help of sensor 4 and controller 3. If the fluid level is not above the predetermined position, fill the reservoir and then start the operation of visual indication device 17. Then the heater system is fluidly coupled with said visual indication device 17 via first conduit 14 and second conduit 15. Ensure leakage free assembly of conduits between said visual indication device 17 and the heater system. Start the visual indication device 17 manually and initiate the heater testing operation by keeping the control switch 12 in ON condition thereby to completely open the control valve 13. At this stage, check for any leakage in the heater system assemblies. Then keep the control switch 12 in completely closed condition and check for any flow in the transparent tube 16. If any flow is observed in the transparent tube 16, which indicates that, the control valve 13 is not properly functioning. Then, the heater system assembly may be revisited for ensuring proper assembly of fluid flow path lines and control valve assembly. If there is no flow observed in the transparent tube 16, then the va\ve is said to be operating as desired. After confirming effective working of heater system, the testing operation may be stopped and the visual indication device is disconnected from the heater system enclosed with the cabin roof- The testing may be repeated if any unacceptable flow is observed in the transparent tube 16 when the valve is in fully closed position.
Accordingly, the present invention provides a system having visual indication device fluidly coupled with the heater system assembly of

HVAC system for checking efficient functioning of the control valve fluidly communicated therewith and ensuring leakage-free assembly of conduits before assembling the HVAC cabin roof on the vehicle. With this, identification of defects of HVAC system, if any, surfacing after assembling the HVAC cabin roof on the vehicles and diagnosing causes thereof becomes very easy and requires short span of time to resolve the problem without otherwise having to dismantle the entire HVAC system from the vehicle for this purpose. The method of operation of the system is also very simple to work and does not require skilled person to operate the system. Also, the whole system according to the present invention is cost effective, portable and easy to service.
It will be readily appreciated by those skilled in the art that modifications can be made to the invention without departing from the concepts disclosed in the foregoing description. Accordingly, the particular embodiments described in detail herein are illustrative only and are not limiting to the scope of the invention, which is to be given the full breadth of the appended claims and any all equivalents thereof.

We claim:
1) A system for checking functioning of a control valve fluidly
communicated with a closed loop hydraulic system comprising:
a visual indication device having provided with a first port and a second port for fluidly communicating with the hydraulic system;
a transparent tube fluidly communicated with said second port of the visual indication device;
a first conduit having first end fluidly communicated with said first port of the visual indication device;
a second conduit having first end fluidly communicated with said transparent tube;
wherein said visual indication device fluidly communicated with the closed loop hydraulic system, comprising:
a reservoir for containing fluid that is to be circulated with the hydraulic system;
a motor-pump unit including a motor and a pump for pumping the fluid contained in said reservoir to the hydraulic system;
a start-push button for activating the visual indication device;
a stop-push button to suspend the operation of the visual indication device;
at least a fluid level sensor;
at least a pressure sensor;
at least a timer;
at least a contactor coil; and
a controller configured with said pressure sensor, said timer and the motor-pump unit.

2) The system as claimed in claim 1 wherein said hydraulic system is adapted to be used as a heater system of HVAC system.
3) The system as claimed in claim 1 wherein said control valve is a mechanically operated and mechanically actuated valve.
4) The system as claimed in claim 1 wherein said control valve is fluidly communicated with second end of said first conduit and first end of a third conduit, second end of which is fluidly connected with the heater core of the heater system.
5) The system as claimed in claim 1 comprising a variable frequency drive for achieving variable flow rate of fluid through the hydraulic system, wherein said variable frequency drive is configured with at feast a sensor for sensing the flow rate of the fluid in the hydraulic system and a switch for adjusting the flow rate in the hydraulic system.
6) The system as claimed in claim 1 comprising a miniature circuit breaker to have overload protection of the system.
7) A method for checking functioning of a control valve fluidly
communicated with a closed loop hydraulic system comprising:
fluidly communicating a visual indication device to the hydraulic system via a first conduit, a second conduit and a transparent tube;
checking level of fluid contained in a reservoir present in the visual indication device;
keeping the control valve in fully closed condition;
actuating a motor-pump unit to pump the fluid contained in the reservoir to the hydraulic system;

observing any flow of the fluid through the transparent tube fluidly communicated with outlet of the hydraulic system;
observing pressure developed in the first conduit from display board positioned in the visual indication device.
8) The method for checking functioning of a control valve fluidly communicated with a closed loop hydraulic system as claimed in claim 7 wherein level of fluid contained in the reservoir is sensed by at least a fluid level sensor and output signal is given to the display board.
9) The method for checking functioning of a control valve fluidly communicated with a closed loop hydraulic system as claimed in claim 7 wherein if the fluid level in the reservoir is not above the predetermined level, then the reservoir is filled with the fluid to activate the visual indication device.

10) The method for checking functioning of a control valve fluidly communicated with a closed loop hydraulic system as claimed in claim 7 wherein the maximum allowable pressure limit set in the first conduit is 2 bar.
11) The method for checking functioning of a control valve fluidly communicated with a closed loop hydraulic system as claimed in claim 7 wherein the timer is set for 3 seconds.
12) The method for checking functioning of a control valve fluidly communicated with a closed loop hydraulic system as claimed in claim 7 wherein the controller is configured in such a way that the visual indication device remains active for 3 seconds once the pressure limit

reaches 2 bar in the first conduit, and then the motor-pump unit automatically gets suspended.
13) A system and method for checking functioning of a control valve fluidly communicated with a closed loop hydraulic system incorporated with a HVAC system comprising:
a visual indication device having provided with a first port and a second port for fluidly communicating with the hydraulic system;
a transparent tube fluidly communicated with said second port of the visual indication device;
a first conduit having first end fluidly communicated with said first port of the visual indication device;
a second conduit having first end fluidly communicated with said transparent tube;
wherein said visual indication device comprising:
a reservoir, a motor-pump unit, a start-push button, a stop-bush button, at least a fluid level sensor, at least a pressure sensor, at least a timer, at least a contactor coil, and a controller;
wherein the method comprising:
fluidly communicating the visual indication device to the hydraulic system via the first conduit and the second conduit;
checking level of fluid contained in the reservoir present in the visual indication device;
keeping the control valve in fully closed condition;
actuating the motor-pump unit to pump the fluid contained in the reservoir to the hydraulic system;

observing any flow of the fluid through the transparent tube fluidly communicated with outlet of the hydraulic system;
observing pressure developed in the first conduit from display board positioned in the visual indication device;
wherein the controller is configured in such a way that the visual indication device remains active for 3 seconds once the pressure limit reaches 2 bar in the first conduit, and then the motor-pump unit automatically gets suspended.
14) A system and method for checking leakage of a closed loop hydraulic system incorporated with a HVAC system comprising:
a visual indication device having provided with a first port and a second port for fluidly communicating with the hydraulic system;
a transparent tube fluidly communicated with said second port of the visual indication device;
a first conduit having first end fluidly communicated with said first port of the visual indication device;
a second conduit having first end fluidly communicated with said transparent tube;
checking level of fluid contained in a reservoir present in the visual indication device;
keeping the control valve in fully opened condition;
actuating a motor-pump unit to pump the fluid contained in the reservoir to the hydraulic system;
a variable frequency drive for achieving variable flow rate of fluid through the hydraulic system, wherein said variable frequency drive is configured with at least a sensor for sensing the flow rate of the fluid in

the hydraulic system and a switch for adjusting the flow rate in the hydraulic system;
observing any flow of the fluid through the transparent tube fluidly communicated with outlet of the hydraulic system;
observing pressure developed in the system.