Claims:We Claim:
1. A CNG parallel pressure regulator system, comprising:
a CNG cylinder valve mounted on a cylinder having two outlets;
a pair of variable pressure regulators coupled in parallel by inlets to CNG valve at one side and outlets to T-connector at other side;
a T- connector port connected to the CNG fuel supply system through a flexible hose.
2. The CNG parallel pressure regulator system (100) according to claim 1, wherein one of the pressure regulators (101) is set at slightly higher pressure than the other pressure regulator (102).
3. The CNG parallel pressure regulator system (100) according to claim 1, wherein outlet of the pair of variable pressure regulators are connected to T- connector through flexible hoses.
4. The CNG parallel pressure regulator system (100) according to claim 1, wherein inlets of a pair of variable pressure regulators are connected to CNG cylinder valve through steel tube assembly.
5. The CNG parallel pressure regulator system (100) according to claim 1, wherein a port of the T- connector connected to CNG fuel supply to vehicle engine through a flexible hose.
, Description:Field of the invention
The present invention relates to a CNG fuel system and more particularly it relates to CNG pressure regulator system used in air cooled engines / vehicles.
Background of the invention
Compressed natural gas is a fuel gas made of natural gas, which is mainly composedof methane (CH4). A number of different and varied applications utilize compressed natural gas (CNG). These applications include the automotive industry in which CNG flow regulator systems have been employed for motorized vehicles and the like. In general, compressed natural gas (CNG) refers to gas compressed at about 200 atm to use as automobile fuel. It is compressed at high pressure and has a specific gravity of 0.61, which is lighter than air specific gravity 1. It spreads easily in case of leakage, and is evaluated as a safe fuel compared to gasoline, diesel, and LPG.
The CNG regulator of a vehicle using such CNG as a fuel serves to decompress the high-pressure CNG gas and then maintain it at a constant pressure. However, the expansion of high-pressure gas to low pressure creates a very large temperature drop when the engine is driven at high speed for a long time or idle (IDEL). Conventional CNG regulator vehicles have a problem in that due to subcooling of CNG regulator when the engine is driven at high speed for a long time or idle (IDEL). In addition to this if the weather condition is humid and/or cold the atmospheric moisture gets condensate on the CNG pressure regulator in water droplets form. Continual operation of the CNG pressure regulator drastically drops its temperature and the water droplets condensate on CNG pressure regulator body gets frozen resulting icing on the body of CNG pressure regulator. This freezing effect affects the normal operation of the CNG pressure regulator and its outlet pressure start dropping from its initial set value. The continuous operation of the CNG pressure regulator further drops the temperature which results in increasing the freezing/icing effect on the CNG pressure regulator to such an extend that its outlet pressure drops to zero that is to atmospheric pressure and flow through the CNG pressure regulator stops completely. This phenomenon adversely affects the working of the engine/ vehicle to which this CNG pressure regulator is supplying the natural gas as per engine requirement to such an extent that the engine stop working.
A prior patent document JP3497543B2 discloses the arrangement of a regulator for adjusting the pressure of compressed natural gas supplied to a water-cooled compressed natural gas engine. The system is composed of the first regulator and the second regulator. The first and second regulators are arranged between the engine and the heat exchanger provided there. The branch passage of the cooling water passage from the engine to the heat exchanger is provided and the first regulator is connected to the water passage. A subsequent piping is integrated into a unit. The hot water in the cooling water passage warmed by the engine is guided to the water passage. However, the arrangement of water passage increases area overhead and pressure regulator temperature maintaining mechanism is complicated and the thermal efficiency is not good.
A conventional CNG regulator vehicle uses Engine coolant to prevent freezing inside regulator. A heated engine coolant must be circulated through the regulator. But Engine coolant must be maintained for at least -45 C antifreeze protection due to the extreme cold of the gas. If the coolant gets freeze in the regulator, the regulator maybe damaged.
Conventionally, a thermostat and a water jacket are used to mitigate the subcooling of CNG. The conventional CNG regulator turns on/off the thermostat according to the specific temperature of the cooling water, so that precise cooling water flow rate control is impossible. In addition, after the coolant is introduced, the length of the circulating flow path is short, so that the CNG supplied at a high pressure is supercooled, which causes a problem in that the outlet pressure of the CNG regulator cannot be constantly maintained.
Accordingly, pressure regulator system that provide uninterrupted supply of CNG to the air cooled engine of a vehicle, that overcomes the problems of prior art technology.
Objects of the invention
An Object of the present invention is to maintain the uninterrupted supply of CNG to the air cooled engine even in high humid and very low temperature condition.
Another object of the present invention to provide a pressure regulator for CNG operated vehicles that is not affected by cooling of gas due to pressure reduction/adiabatic expansion.
Yet, another object of the present invention to provide a regulator for CNG fuel operated engine, which is capable of preventing constriction or blocking of a high pressure gas conduit due to freezing of fuel gas components therein.
One more object of the invention to provide a regulator for CNG fuel operated engine, which can suitably prevent constriction of a high pressure CNG conduit due to freezing of fuel CNG regulator components therein.
Yet another object of the parallel CNG pressure regulator system is to avoid use of any outsource of energy/ Electricity, hot water source to overcome the freezing problem of the CNG pressure regulator.
Yet another object of the present invention to automatically maintain supply of CNG to the engine through one of its pressure regulator when other pressure regulator stop supply due to freezing.
Yet another object of the present invention to avoid use of any sensor or device to switch over from active CNG pressure regulator to stand by CNG pressure regulator and vice versa.
One more object of the present invention is to provide an efficient and cost effective, easy to assemble pressure regulator system for CNG operated vehicles.
Summary of the invention
The present invention relates to a CNG pressure regulator system used in air cooled engines vehicles to provide uninterrupted flow of CNG fuel supply to the vehicle engine. According to an embodiment of the present invention, the parallel pressure regulator system comprising two pressure regulators coupled in parallel using CNG valve of a cylinder and T- connector. Pressure of one of the regulator is set at slightly higher than the other. The higher pressure regulator remains active during normal working condition, hence reflect as active pressure regulator. The low pressure regulator supply CNG fuel to the vehicle engine when active pressure regulator stops working, hence reflect as standby pressure regulator. A CNG valve including two outlet port mounted on the CNG cylinder. One of the outlet port of CNG valve is connected to the inlet port of active pressure regulator and the other outlet port of CNG valve is connected to the inlet port of standby pressure regulator. Outlet ports of the both the pressure regulators are connected to T-connector through flexible hoses. One of the port of the T-connector connected to the CNG fuel supply of vehicle engine. The CNG cylinder pressure (normally 200 bar in full condition of cylinder) is reduces by the active pressure regulator and stand by pressure regulator at a desired pressure. During normal working condition, only active pressure regulator supply CNG fuel to vehicle engine. Condensation and ice start depositing on active pressure regulator due to the continuous operation, affecting drop in its outlet pressure. When the outlet pressure of the active pressure regulator drops below the set pressure of the stand by pressure regulator, the CNG flow through Stand by pressure regulator starts and the engine get uninterrupted supply of CNG fuel through the stand by pressure regulator. Active pressure regulator starts building to normal set pressure value after some time and the CNG fuel flow through the active pressure regulator starts and the engine get uninterrupted supply of CNG through the active pressure regulator. Hence, the parallel pressure regulator system eliminates the use of anti- freezing agent, hot water, long conduit passage to maintain the pressure regulator temperature. According to the embodiment of the present invention, parallel arrangement of variable pressure regulators provides uninterrupted fuel supply to vehicle engine due to automatic switching between active and standby pressure regulator according to drop in their outlet pressure due to adiabatic expansion.
Brief description of the drawings
The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
FIG. 1 is a Pressure regulator system as per prior art;
FIG. 2 (i, ii) illustrates Parallel Pressure regulator in accordance with the preferred embodiments of present invention;
FIG. 3 illustrate the ice formation on pressure regulator during road trial using single pressure regulator;
FIG. 4 illustrate ice formation on active pressure regulator in Parallel Pressure Regulator System fitted vehicle.

Detailed description of the invention
The foregoing objects of the invention are accomplished and the problems and shortcomings associated with the prior art techniques and approaches are overcome by the present invention as described below in the preferred embodiment. The following description includes the preferred best mode of one embodiment of the present invention. It will be clear from this description of the invention that the invention is not limited to these illustrated embodiments but that the invention also includes a variety of modifications and embodiments thereto.
Therefore, the present description should be seen as illustrative and not limiting. While the invention is susceptible to various modifications and alternative constructions, it should be understood, that there is no intention to limit the invention to the specific form disclosed, but, on the contrary, the invention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined in the claims.
In any embodiment described herein, the open-ended terms "comprising," "comprises,” and the like (which are synonymous with "including," "having” and "characterized by") may be replaced by the respective partially closed phrases "consisting essentially of," consists essentially of," and the like or the respective closed phrases "consisting of," "consists of, the like.
As used herein, the singular forms “a,” “an,” and “the” designate both the singular and the plural, unless expressly stated to designate the singular only.
The present invention relates to a CNG fuel system and more particularly it relates to CNG pressure regulator system used in air cooled engines / vehicles.
The principles of the present invention have particular application to pressure regulators for compressed natural gas-powered vehicles, and thus will be described below chiefly in this context. It will of course be appreciated, and also understood, that principles of this invention may be applicable to other applications where it is desirable to regulator pressure.
According to an embodiment of the present invention, the parallel pressure regulator system (100) comprising two pressure regulators coupled in parallel using CNG valve of a cylinder (106) and T-connector. Pressure of one of the regulators (herein after “active pressure regulator”) is set at slightly higher than the other ( herein after “standby pressure regulator”) . The higher-pressure regulator remains active during normal working condition, hence reflect as active pressure regulator (101). The low-pressure regulator supply CNG fuel to the vehicle engine when active pressure regulator stops working, hence reflect as standby pressure regulator (102).
Referring to the drawings, and initially to Fig. 2 (ii) (Alternate Arrangement), a parallel pressure regulator system (100) is illustrated generally at reference numeral 100. The parallel pressure regulator system (100) includes a Active pressure regulator (101), a Standby pressure regulator (102), a T connector (103), Flexible hoses (104), a Steel tube assembly (105), a CNG cylinder valve (106), a CNG cylinder (107).
A CNG cylinder valve (106) including two outlet ports mounted on the CNG cylinder (107). One of the outlet port of CNG valve is connected to the inlet port of active pressure regulator (101) using steel tube assembly (105). Another outlet port of CNG valve is connected to the inlet port of Standby pressure regulator (102) using steel tube assembly (105). Outlet port of active pressure regulator (101) coupled to the T-connector using flexible hose (104). Outlet port of Standby pressure regulator (102) coupled to the T-connector using flexible hose (104). One of the port of the T- connector is connected to the CNG fuel supply system of the vehicle engine through a flexible hose (104).
The CNG cylinder with cylinder valve is functionally coupled to the both pressure regulators. The CNG cylinder pressure (normally 200 bar in full condition of cylinder) is reduces by the active pressure regulator (101) and Stand by pressure regulator (102) at a desired pressure.
Referring to Fig.2 (ii) (Alternate Arrangement), a Parallel CNG pressure regulator system (100) is illustrated, including two different CNG pressure regulators. The Active pressure regulator (101) is set at slightly higher pressure than the Stand by pressure regulators (102).
The CNG pressure regulator employs a diaphragm in association with a gas flow control valve, the diaphragm being responsive to the air pressure to control the gas flows into the decompressing chamber from a high-pressure gas passage. However, the pressure reduction by such an arrangement causes the high pressure gas conduit is cooled by adiabatic expansion of the fuel gas as it is released into the decompressing chamber from the high pressure conduit, freezing water vapour present in CNG as an impurities in that region, especially in the high pressure gas conduit,as a result narrowing the effective area of the conduit to block the fuel gas flow and lowering the performance quality of the engine. The water vapor present in CNG as an impurities start freezing due to adiabatic expansion of the gas during the sudden decompression and vehicle engine stops working. Therefore, there has been proposed a parallel pressure regulator system (100) which is arranged to bypass the CNG to other pressure regulator for continue flow of gas supply to vehicle engine.
With the regulator for CNG fuel operated engines according to the present invention, the fuel CNG begins to flow upon starting an engine, and the temperature of the components of the regulator and its parts around drops due to adiabatic expansion of the CNG fuel.
In normal operation of the system, active pressure regulator (101) supplies CNG to engine side. The outlet of active pressure regulator (101) and Stand by pressure regulator (102) are inter connected by T-connector, the higher outlet pressure of the active pressure regulator (101) acts on the stand by pressure regulator (102) outlet side which is set for slightly lower value affecting closer of flow through that Stand by pressure regulator (102). During normal working condition, only active pressure regulator (101) supply CNG to t h e vehicle engine. Due to the continuous operation of the active pressure regulator (101), condensation and further icing start depositing on the active pressure regulator (101) affecting drop in its outlet pressure.
Moment the outlet pressure of the active pressure regulator (101) drops below the set pressure of the Stand by pressure regulator (102), the CNG flow through Stand by pressure regulator starts and the engine get uninterrupted supply of CNG through the Stand by pressure regulator (102). As there is no CNG passing through the active pressure regulator (101), the condensation/ icing effect on the active pressure regulator (101) start minimizing resulting the outlet pressure of active pressure regulator (101) starts building to normal pressure value after some time.
When the icing on the Active pressure regulator (101) melts, the outlet pressure of Active pressure regulator (101) again achieves its set value. As the Active pressure regulator’s (101) outlet pressure touches to the set threshold higher pressure than standby pressure regulator (102) pressure, the CNG flow through t h e active pressure regulator (101) starts and the engine get uninterrupted supply of CNG through the Active pressure regulator (101). As the outlet pressure of the active pressure regulator (101) is slightly higher than that of stand by pressure regulator (102), the stand by pressure regulator flow stops automatically. The switching of regulator cycle continuously repeats and the engine gets uninterrupted supply of CNG fuel through this parallel CNG pressure regulator system.
In accordance with the present invention, a field trial conducted with parallel pressure regulator system as well as with single pressure regulator system as per prior art.
Example 1: Trial conducted with a single pressure regulator system as per prior art
A vehicle is fitted with single pressure regulator as per prior art is set a t pressure 6 Kg/cm² in max flow condition. Pressure gauge is mounted to observe outlet pressure of pressure regulator in vehicle running condition as shown in Figure 5.
Digital temperature measuring unit fitted on vehicle and a sensor fitted on pressure regulator as shown in Figure 5 to observe pressure regulator temperature during continuous running of vehicle.
Vehicle with single pressure regulator started at 6°C environmental temperature. Vehicle continuously ran for 95 km.
Observation:
1. Ice formation observed on pressure regulator after completion of running of 20 to 25km as shown in Figure 3.
2. Outlet pressure of Pressure Regulator drops from 6 kg to 0.63 Kg/cm².
3. Vehicle power and pick-up loss was observed after continuous running of 60 km due to the pressure drop at outlet of pressure regulator and finally vehicles stop running after 95 km.
TEST REPORT OF ON ROAD TRIAL USING SINGLE PRESSURE REGULATOR AS PER PRIOR ART.

SR. NO. Kms Running PRESSURE REGULATOR
Temperature in °C PRESSURE REGULATOR OUTLET PRESSURE IN Kg/cm2
1 0 10.2 6
2 10 4 6
3 20 -2 6
4 30 -8 5.8
5 40 -11 5.5
6 50 -12 5
7 60 -14 4.9
8 70 -14 4.6
9 80 -17 4
10 85 -20 3
11 95 -22 0.63

Table 1

Trial conducted with Parallel Pressure regulator system:
Example 2: Trial conducted with Parallel Pressure regulator system as per the present invention. The same vehicle converted on Parallel Pressure Regulator system as per the present invention as shown in fig.2 (I) (alternate view) (I) (alternate view). A pressure gauge mounted to observe outlet pressure of pressure regulator in vehicle running condition. Digital temperature measuring unit fitted on vehicle and a sensor fitted on pressure regulator to observe pressure regulator temperature during continuous running of vehicle. Active pressure regulator (101) outlet pressure set at 6 Kg/cm² in flow condition and stand by pressure regulator outlet pressure set at 5 Kg/cm² in flow condition.Vehicle with Parallel pressure regulator system (100) started at 6 °C environmental temperature. Vehicle continuously run for 95 km and our observations are as follows.
1. Ice Observed on Active pressure regulator (101) after completion of 20km to 25km.
2. Outlet pressure of Active pressure regulator (101) drops from 6 kg/cm² to below 5 kg/cm² after completion of 50 km.
3. Immediately after Active pressure regulator (101) pressure drops below 5 kg/cm², the Stand by Pressure Regulator (102) starts functioning and automatically start supply to the system.
1. 4. Neither pick-up nor power lose was observed during continuous vehicle running for 95 km.
In Parallel Pressure Regulator System fitted vehicle, ice formation observed only on Active Pressure Regulator (101). There is neither ice formation nor negative temperature observed on Standby pressure regulator (102).
TEST REPORT OF ON ROAD TRIAL USING PARALLEL PRESSURE REGULATOR SYSTEM AS PER PRESENT INVENTION

SR. NO.
Kms Running ACTIVE PRESSURE REGULATOR
Temperature °C STAND BY PRESSURE REGULATOR
Temperature °C PRESSURE REGULATOR OUTLET PRESSURE IN
Kg/cm2
1 0 8.1 10.8 6
2 10 -4 10 6
3 20 -12 9 5.8
4 30 -14 9 5.8
5 40 -15 9 5.5
6 50 -16 9 4.9
7 60 -15 8 5
8 70 -16 7 4.9
9 80 -15 6 4.6
10 85 -15 5 4.5
11 95 -14 4 4.2

Table 2

From the example 1 and example 2, it is clearly observed that in a Single Pressure Regulator fitted vehicle a s per prior art, the temperature drops to -22°C and ice formation observed on Pressure Regulator after 20-25 km running of vehicle. Power and pick-up loss was observed in vehicle after running 60 km and vehicle stops running after 95km.
In Parallel Pressure Regulator System fitted vehicle as per present invention, temperature drops to -16°C and ice formation observed only on Active pressure regulator (101) after 20-25 km running of vehicle. There is neither ice formation nor negative temperature observed on Standby pressure regulator (102).
Immediately after Active pressure regulator (101) pressure drops below 5 kg/cm², the Stand by Pressure Regulator (102) starts functioning and automatically start CNG supply to the system. Neither pick-up nor power loss was observed during continuous vehicle running for 95 km. With the parallel pressure regulator system (100), the vehicles continuously run without any problem.
Although the invention has been shown and described with respect to a certain embodiment or embodiments, it is obvious that equivalent alterations and odifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a "means") used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application. Though the field of the invention has been described herein with limited reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention.
The foregoing objects of the invention are accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiment. Detailed descriptions of the preferred embodiment are provided herein; however, it is to be understood that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure, or matter. The embodiments of the invention as described above and the methods disclosed herein will suggest further modification and alterations to those skilled in the art. Such further modifications and alterations may be made without departing from the spirit and scope of the invention.
Advantages of the present invention
• The system (100) provides automatic switching of regulator without any power or human efforts.
• It greatly reduces the risk of environmental pollution
• It is efficient and requires no power for efficient operation.
• The system (100) structure and arrangement are simple.