WO1989010474A1

WO1989010474A1 - Diesel fuel heater

Info

Publication number: WO1989010474A1
Application number: PCT/US1989/001745
Authority: WO
Inventors: Dennis A. Ray
Original assignee: Ray Dennis A
Priority date: 1988-04-29
Filing date: 1989-04-25
Publication date: 1989-11-02
Also published as: KR900700752A; MX165464B; AU3551589A

Abstract

A diesel fuel heater (10) for heating diesel fuel prior to its introduction into a diesel engine wherein said fuel heater (10) comprises top and bottom covers (12, 13) and an elongate annular section (11) forming a heater transfer chamber (64). The fuel heater (10) of the present invention heats the fuel by passing engine coolant across fuel carrying fuel tubes (37) located in the heat transfer chamber (64). A manually adjustable thermostat (100) for use in such a fuel heater (10) wherein the fuel is heated by engine coolant, with the thermostat (100) including a moveable piston (106) therein to restrict the flow of coolant through the fuel heater (10) in response to changes in the temperature of the heated fuel and having an adjusting screw (101) for manually adjusting the position of the piston (106) to manually adjust the flow of coolant through the fuel heater (10).

Description

DIESEL FUEL HEATER

BACKGROUND OF THE INVENTION

This invention relates to diesel fuel engines, and more particularly, to devices that preheat diesel fuel for use in these engines.

It is well known that heating fuel prior to its introduction into the combustion chamber increases the efficiency of diesel engines. There are many obstacles to overcome when designing a diesel fuel heating device. The object of these fuel heaters is to provide the combustion chamber with diesel fuel that is warmed to a predetermined temperature. The heat output of the fuel heater must be adjustable to satisfy the different amounts of fuel needed, depending on whether the truck is idling or accelerating. The fuel heater must also work within a wide range of environmental temperatures and pressures. The heat output required from the fuel heater at warm temperatures is much less than the heat output required when the outside temperature is below zero.

The fuel heaters must be inexpensive to manufacture and relatively easy to install. Savings from this type of device occur over an extended period of time due to increased fuel savings. Additionally, fuel heaters of this type decrease the amount of harmful emissions created by a diesel engine.

The prior art contains many attempts to overcome the problems faced when designing a gasoline

SUBSTITUTE SHEET fuel heater. In U.S. Patent No. 4,146,002, issued to Quinn on March 27, 1979, the gasoline is heated by passing it through helically shaped tubing that is surrounded by engine coolant. My prior invention, U.S. Patent No. 4,367,717, issued January 11, 1983, also utilizes engine coolant to heat the fuel. In this invention the fuel is passed through a heat exchanger which heats and regulates the fuel temperature as it passes into the automobile carburetor. Finally, my co-pending application, Serial No. 121,672 filed on November 17 , 1987, also utilizes engine coolant to heat the gasoline prior to its introduction into the carburetor.

One attempt to overcome the many problems unique to diesel fuel heaters is disclosed in U.S. Patent No. 4,700,047, issued to Crossett on October 13, 1987. The Crosset patent discloses the use of an elongate heat exchange coil which is coiled inside a coolant containing housing. The use of a coiled heat exchange coil to transfer heat from the coolant to the fuel limits the ability of the fuel heater to heat the fuel in common winter temperatures unless the coolant is preheated or the heat exchange coil is lengthened.

The presently available thermostats for these fuel heaters operate by monitoring the temperature of either the fuel or coolant and once the fuel or coolant reaches a predetermined temperature, the flow of the coolant through the heat exchange chamber is blocked until such time as the temperature of the fuel decreases

SUBSTITUTESHEET to its predetermined, preferred temperature. At present, the efficiency of these thermostats is decreased whenever the flow rate or pressure of the coolant or fuel fluctuates. These fluctuations may be caused by a defective water pump; fuel pump or even by the sudden acceleration of the engine. Quite often, when the flow rate or pressure of the coolant fluctuates, the thermostat will stick in the open or closed position and the fuel heater will not operate properly. The present invention addresses the problem by being much more sensitive to the overall fluctuations in flow rate and pressure of the coolant or fuel while being less sensitive to the sudden fluctuations in flow rate or pressure.

Additionally, the flow of fuel and coolant in the present invention is arranged so as to flow perpendicularly to the various elements of the thermostat. This overcomes the problem which occurred in some of the prior thermostats wherein a sudden increase in the demand for coolant would draw the needle valve towards the needle valve housing and restrict the flow of coolant in the fuel heater. Another approach has been to direct the coolant inwardly perpendicular to the needle valve. Over a period of time this will cause the needle valve to improperly seat in the needle valve housing and greatly reduce the efficiency of the needle valve.

The above described inventions illustrate some of the characteristics common to fuel heaters. The present invention addresses the need for a diesel fuel heater capable of overcoming the many problems unique to diesel fuel and the operating pressures of diesel engines. Therefore, due to the large number of diesel

SUBSTITUTESHEET trucks present in our society and the limited fuel resources available, the need remains in the art for a diesel fuel heater which will improve combustion efficiency and decrease the amount of pollution created by these diesel engines.

SUMMARY OF THE INVENTION

An object of this invention is to produce a reliable diesel fuel heater which is adjustable to fit in any type of diesel engine compartment.

Another object of this invention is to provide a diesel fuel heater that evenly heats the diesel fuel and is capable of providing diesel fuel to the combustion chamber of the diesel engine at a predetermined temperature and reliable flow rate.

Another object of this invention is to create a diesel fuel heater that will enable the diesel engine to burn diesel fuel more efficiently and thereby reduce the amount of unburned fuel that is released into the atmosphere.

Another object of this invention is to provide a diesel fuel heater that is capable of operating at the increased fuel and coolant pressures present in diesel engines.

Another object of this invention is to produce a thermostat which operates efficiently in pressure ranges of 5 psi to 100 or more psi.

Another object of this invention is to provide a thermostat for fuel heaters which will enable the fuel heater to evenly heat the fuel while being responsive to gradual fluctuations in the flow rate and pressure of the coolant and fuel in the fuel heater.

Another object of this invention is to provide a thermostat which may be manually adjusted and will further respond automatically to the changes in the temperature of the fuel.

A feature of this invention is a two piece elongate annular section comprised of upper and lower coolant rings and having attached top and bottom covers. Inwardly from the coolant rings is a coolant distributor and a heat exchanger. The lower coolant ring cooperates with the coolant distributor to form a coolant distribution passageway near the top end of each coolant ring. The lower coolant ring includes a coolant inlet to allow coolant to pass into the interior of the diesel fuel heater. The upper coolant ring includes coolant passageways to allow the coolant to pass from the interior of the diesel fuel heater into a coolant removal chamber in the top cover.

Inwardly from the upper and lower coolant rings is the coolant distributor. The outer surface of the coolant distributor includes a pair of top and bottom O-rings and an annular obstruction to force the coolant from the coolant distribution passageway into the heat transfer chamber through the lower coolant passageways. In the heat transfer chamber of the diesel fuel heater the coolant flows across the fuel carrying fuel tubes and upwardly through the heat transfer chamber. The coolant then flows out of the heat transfer chamber through the upper coolant passageways located near the top of the coolant distributor. The heat exchanger is located inwardly from the coolant distributor. The heat exchanger is constructed of brass or any other nonreactive metal and consists of upper and lower fuel basins. These fuel basins are connected together by numerous fuel tubes. The lower fuel basin cooperates with the bottom cover to form a lower fuel collection area. From this fuel collection area the fuel is spiraled upwardly by inserts in the fuel tubes which pass through the heat transfer chamber. From the heat transfer chamber, the fuel passes into the upper fuel basin to the top fuel collection area.

The bottom cover includes a fuel inlet which delivers unheated diesel fuel from the fuel tank into the fuel heater. In the bottom cover, a fuel distributor distributes fuel into the lower collection area. From this lower fuel collection area, the fuel flows into the fuel tubes.

The top cover attaches to the inner surface of the upper fuel basin and the top surface of the upper coolant ring. The top cover includes a fuel outlet and a coolant outlet. The top cover also includes an adjustable thermostat which expands or contracts according to the temperature of the fuel as it leaves the fuel heater. If the fuel is too hot, the thermostat will expand and prevent the coolant from flowing out of the coolant outlet. As the exiting fuel cools, the thermostat will contract and the coolant will once again flow through the fuel heater.

In operation, the diesel fuel enters the bottom of the fuel heater through the fuel inlet. The fuel

SUBSTITUTESHEET then passes through the fuel distributor and into the lower fuel collection area. From the lower fuel collection area, the fuel flows into the fuel tubes where it is spiraled upwardly until it reaches the upper fuel basin. As the fuel passes through the fuel tubes, heat is transferred from the coolant to the fuel tubes, and ultimately, to the diesel fuel. From the upper fuel basin the fuel passes into the top fuel collection area and flows around the temperature sensing element of the thermostat. Finally, the heated fuel flows out of the top cover through the fuel outlet. From the fuel outlet, the fuel passes into the combustion chamber of the diesel engine.

The engine coolant enters the fuel heater through the coolant inlet located on the lower coolant ring. The coolant then passes through the lower coolant distribution passageway; through the lower coolant passageway on the coolant distributor and into the heat transfer chamber. The coolant then transfers heat'to the fuel tubes and flows upwardly to the top of the heat transfer chamber. The coolant then flows out of the heat transfer chamber through the upper coolant passageways located near the top of the coolant distributor. The coolant then passes through the upper coolant distribution passageway, into the the coolant removal chamber in the top cover and past the needle valve of the adjustable thermostat. Finally, the coolant flows out of the top cover through the coolant outlet and into the engine coolant system.

Another feature of this invention is to provide a thermostat which will automatically adjust the flow of coolant through the fuel heater according to the predetermined or preferred range of fuel temperatures in

SUBSTITUTE SHEET the fuel heater. Additionally, the thermostat may be manually adjusted to either restrict or completely block the flow of coolant through the fuel heater.

In an alternate embodiment of the invention, the thermostat consists of an adjusting screw; a heat insulator? a power pill housing; a power pill; an insulating extension; a piston and an adjustable cylinder. The adjusting screw extends from the outer surface of the top cover of the fuel heater and into the top cover to a point adjacent to the fuel outlet. The inner end of the adjusting screw contacts the heat transfer end of the power pill housing. The heat transfer end of the power pill housing extends across the fuel outlet and is in flow communication with the heated fuel. The second end of the power pill housing is enclosed by the heat insulator and is retained in the heat insulator by a pair of O-ring and grooves which frictionally contact the inner surface of the heat insulator. The heat insulator is retained in the top cover at a point adjacent to the fuel outlet by a pair of O-rings and grooves which frictionally fit between the top cover and the heat insulator.

The interior of the power pill housing encloses the power pill and the extension end of the insulating extension. The power pill expands or contracts according to the temperature of the heated fuel as the fuel passes around the outer surface of the power pill housing. The extension end of the insulating extension is enclosed by the power pill housing and is in a contacting relation with the power pill. As the power pill expands, the insulating extension is moved beyond the power pill housing to contact the piston. The piston balances the pressure created by the expansion of the power pill with the opposite pressure created by a spring located within the adjustable cylinder. As the power pills expands, the insulating extension pushes against the piston which in turn compresses the spring and restricts the flow of coolant through the adjustable cylinder. Additionally, the piston utilizes a bleed port to allow coolant to equalize the pressure between the insulating extension and the spring in the adjustable cylinder.

In operation, the preferred operating ranges for this thermostat are determined primarily by the temperature range of the power pill chosen. Additionally, once the fuel heater is installed, the thermostat may be fine tuned by adjusting the adjusting screw to obtain the optimum flow of coolant through the adjustable cylinder and fuel heater. Finally, if the fuel heater is not operating properly, the fuel heater may be turned off by merely rotating the adjustable cylinder to its off position.

An advantage of the present invention is that the fuel is evenly heated in the heat transfer chamber.

Another advantage of the present invention is that the thermostat is adjustable to account for the blend of the fuel, the outside temperature and the barometric pressure to provide the optimum fuel temperature for engine combustion.

Another advantage of this invention is that it provides increased fuel efficiency and decreases the amount of unburned fuel released into the atmosphere.

SUBSTITUTE SHEET Another advantage of this invention is that it holds sufficient heated fuel in reserve so that it easily adjusts to sudden increases in the demand for. fuel.

Another advantage of this invention is that it is safe to use and will shut the coolant flow off if the fuel reaches a predetermined temperature.

Another advantage of this invention is that it overcomes the many problems created by the relatively high fuel and coolant pressures used in the operation of diesel engines.

Another advantage of the present invention is that the thermostat is adjustable to account for the blend of the fuel, the outside temperature and the coolant and fuel flow rates to provide the optimum fuel temperature for engine combustion.

Another advantage of this invention is that the thermostat may be manually rotated to shut down the fuel heater if the fuel heater is not operating properly.

DESCRIPTION OF THE DRAWINGS

Fig. 1 is a perspective view of the diesel fuel heater;

Fig. 2 is a detailed cross-sectional view of the diesel fuel heater taken along lines 2-2 of Fig. 1;

Fig. 3 is a detailed cross-sectional view of the diesel fuel heater taken along lines 3-3 of Fig. 2; Fig. 4 is a detailed cross-sectional view of the diesel fuel heater taken long lines 4-4 of Fig. 2;

Fig. 5 is a detailed cross sectional view of the diesel fuel heater taken along lines 5-5 of fig. 2;

Fig. 6 is an exploded view of an alternate version of an adjustable thermostat used in the present invention;

Fig. 7 is a side view of the coolant distributor of the present invention;

Fig. 8 is a side view of the heat exchanger of the present invention;

Fig. 9 is a perspective view of the bottom cover of the present invention;

Fig. 10 is a perspective view of the upper coolant ring of the present invention.

Fig. 11 is a perspective view of a diesel fuel heater utilizing the present invention;

Fig. 12 is a detailed cross-sectional view of the fuel heater taken along lines 12-12 of Fig. 11;

Fig. 13 is a detailed cross-sectional view of the fuel heater taken along lines 13-13 of Fig. 11;

Fig. 14 is an exploded cross-sectional view of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

One form of the fuel heater is described herein and is referred to generally as 10. The fuel heater 10 has as its principal parts, a central annular section 11, a top cover 12 and a bottom cover 13. The central annular section 11 is comprised of two concentric walls which, in combination with the top and bottom covers 12 and 13, create a heat transfer chamber 64. The first concentric wall is comprised of an upper coolant ring 14 and a lower coolant ring 15 which, in combination, extend from the top cover 12 to the bottom cover 13. The next concentric wall is the coolant distributor 16 which, in combination with the upper and lower coolant rings 14 and 15, form upper and lower coolant distribution passageways 65 and 66. Located inwardly from the coolant distributor 16 and extending through the heat transfer chamber 64 is the heat exchanger 17.

The upper coolant ring 14 is an elongate annular aluminum cylinder which extends from the bottom of the top cover 12 to an overlapping relationship with the lower coolant ring 15. The outer surface of the upper coolant ring 14 includes a circumferential ridge 72 for the attachment of an adjustable mounting bracket 18 thereon. The top surface of the upper coolant ring 14 includes a top annular O-ring and groove 19 to provide a leak proof seal with the top cover 12. Additionally, the top surface of the upper coolant ring 14 includes threaded openings thereon for the insertion of set screws 20 to fasten the top cover 12 onto the upper coolant ring 14. The inner surface of the upper coolant ring 14 includes a central annular ridge 23 for engagement with the outer surface of the coolant distributor 16. Positioned along the lower outer surface of the upper coolant ring 14 is a pair of O-rings and grooves 21 and 22 which, in combination with the lower inner surface of the lower coolant ring 1.5, form a leak-proof seal. Positioned immediately above the O-ring and grooves 21 and 22, is a lower annular ridge 24 which, in combination with set screws 25, enables the lower coolant ring 15 to be rotatably attached to the upper coolant ring 14.

The lower coolant ring 15 is another elongate aluminum cylinder which extends from an overlapping relationship with the upper coolant ring 14 to the bottom cover 13. The lower coolant ring 15 includes a coolant inlet 26 and may be rotated to position the coolant inlet 26 for the convenient attachment of the fuel heater 10 to the diesel engine's pre-existing coolant system. The inner surface of the bottom of the lower coolant ring 15 includes an annular bottom cover ridge 27 which circumferentially engages the bottom cover 13.

The next concentric wall in the central annular section 11 is the coolant distributor 16. This wall is constructed of aluminum and contains evenly spaced upper and lower coolant passageways 28 and 29 which open into the heat transfer chamber 64. The outer surface of the coolant distributor 16 includes an annular distributor ridge 30 which rests on the central annular ridge 23 of the upper coolant ring 14. The coolant distributor 16 is further held in position by a pair of centrally located O-rings and grooves 31 and 32 which engage the inner surface of the upper coolant ring 14 to form a leak proof seal between the coolant distributor 16 and the upper coolant ring 14. The lower outer surface of

SUBSTITUTE SHEET the coolant distributor 16 includes a pair of bottom O-rings and grooves 33 and 34 which engage the inner surface of the lower coolant ring 15 to create a leak proof seal between the coolant distributor 16 and the lower coolant ring 15.

Located inwardly from the coolant distributor 16 is the heat exchanger 17. The heat exchanger 17 is preferably constructed of brass or other nonreactive material and consists of a top fuel basin 35, a bottom fuel basin 36 and centrally located fuel tubes 37. In the present invention, at least 16 fuel tubes 37 are arranged in a pair of evenly spaced circular rows. The top and bottom fuel basins 35 and 36, respectively, in combination with the coolant distributor 16, form the heat transfer chamber 64. The fuel tubes 37 extend upwardly from the bottom fuel basin 36; through the heat transfer chamber 64 and into the top fuel basin 35. The top fuel basin 35 is held in position by a pair of top O-rings and grooves 39 and 40 which engage the inner surface of the coolant distributor 16 to form a leak proof seal between the heat exchanger 17 and the coolant distributor 16. The bottom fuel basin 36 includes a pair of bottom O-rings and grooves 41 and 42 which engage the inner surface of the coolant distributor 16 to form a leak proof seal between the bottom of the heat exchanger 17 and the coolant distributor 16.

The bottom cover 13 is constructed of aluminum and includes the fuel inlet 59. A fuel distributor 60 is in flow communication with the fuel inlet 59 and consists of a top, flat surface and horizontally oriented fuel passageways 61. Located on the inner, bottom surface of the bottom cover 13 is a condensation

SUBSTITUTE SHEET plug 62 to remove condensation from the lower fuel collection area 63. The bottom cover 13 is held in position by a pair of O-rings and grooves 67 and 68 which engage the inner surface of the bottom fuel basin

36 to form a leak proof seal between the bottom cover 13 and the bottom fuel basin 36.

The top cover 12 is preferably constructed of aluminum and includes a fuel outlet 45, a coolant outlet

46 and an adjustable thermostat 47. The adjustable thermostat 47 monitors the temperature of the diesel fuel and limits the flow of coolant through the coolant outlet 46. The adjustable thermostat 47 includes a threaded adjusting screw 48 which extends inwardly into the top cover 12 and has an O-ring 49 and adjustment collar 50 which act in combination to limit the movement of adjusting screw 48 and prevents the flow of fuel out of the fuel heater 10 through the opening for adjusting screw 48. Inwardly from the adjusting screw 48 is an adjustment collar 50 which includes three sealing O-rings 52, 53 and 54 which act in combination with the top cover 12 to prevent the flow of fuel into the coolant removal chamber 70. The heat sensor 51 is inserted into the end of adjustment collar 50 and extends outwardly from the adjustment collar 50 a sufficient distance to engage the power pill 55. The power pill 55 expands and contracts according to the temperature of the fuel and as the power pill 55 expands, it moves the needle valve 56. The needle valve 56 extends into the needle valve housing 58 located on the coolant outlet 46 and includes a tension spring 57.

In operation, the fuel flows into the fuel heater 10 through fuel inlet 59. The fuel then flows into the fuel distributor 60 and through the fuel passageways 61. The fuel passageways 61 force the fuel to flow horizontally into the lower fuel collection area 63. The fuel tubes 37 extend into the lower fuel - collection area 63 a slight distance to prevent the fuel from flowing at varying rates into the individual fuel tubes 37. The fuel heater 10 optimally includes at least 16 fuel tubes 37 which act in combination to decrease the flow rate and pressure of the fuel as the fuel passes through the heat transfer chamber 64. Inside each fuel tube 37 is a tube insert 38 which spirals the fuel through the fuel tube 37 and thereby provides a more efficient transfer of heat from the coolant to the fuel. Once the fuel passes through the the fuel tubes 37, it passes into the top fuel basin 35. The top fuel basin 35 and the top cover 12 form the top fuel collection area 69 to collect the heated fuel and return the fuel to its original pressure and flow rate. From the top fuel collection area 69, the fuel flows across the adjustment collar 50 and heats the heat sensor 51 located in the top cover 12. The fuel then flows out of the fuel heater 10; through the fuel outlet 45 and ultimately into the combustion chamber of the diesel engine.

The coolant enters the fuel heater 10 through the coolant inlet 26 located on the lower coolant ring 15. The coolant then flows through the lower coolant distribution passageway 66 and into the lower coolant passageways 29 located on the coolant distributor 16. Once the coolant flows through the lower coolant passageways 29 it enters the heat transfer chamber 64. In the heat transfer chamber 64, the coolant passes across the outer surface of the fuel tubes 37 to

SUBSTITUTESHEET transfer the heat from the coolant to the fuel tubes 37 and heats the fuel. The coolant flows upwardly through the heat transfer chamber 64 so that the hottest coolant contacts the coolest fuel at the lower end of the heat transfer chamber 64; as the coolant and fuel pass into the upper end of the heat transfer chamber 64, the temperature of the coolant will decrease and the temperature of the fuel will have increased. The coolant passes from the heat transfer chamber 64 into the upper coolant distribution passageway 65 through the upper coolant passageways 28 located near the top end of the coolant distributor 16. The coolant flows upwardly from the upper coolant distribution passageway 65 into the annular coolant flow ring 73 located on the bottom surface of the top cover 12. The coolant then contacts the power pill 55 and needle valve 56 in the coolant removal chamber 70 before it leaves the fuel heater 10 through the needle valve housing 58 located on the coolant outlet 46.

The alternate version of the adjustable thermostat 47' is illustrated in Fig. 6. This embodiment includes an insulator ring 81 and a needle valve insulator 85. The adjustable thermostat 47' may be used as illustrated in Figs. 2 and 3 by merely enlarging the thermostat opening in the top cover 12 adjacent the fuel outlet 45. The insulator ring 81 surrounds the end of the heat sensor 51 which is inserted into the thermostat opening of the top cover 12 and is held in position by O-rings and grooves 82 and 83 and set screw 84. This limits the amount of heat transferred from the fuel to the power pill 55 through the top cover 12. Additionally, in the alternate adjustable thermostat 47', a needle valve insulator 85 replaces the part of needle valve 56 adjacent the power pill 55 thereby decreasing the amount of heat transferred from the power pill 55 to the modified needle valve 56'.

The operation of this fuel heater 10 provides, as it primary advantages, fuel economy and decreased fuel emissions. Additionally, this invention overcomes the problems of the higher operating pressures of coolant and diesel fuel in diesel engines. The use of the adjustable thermostat 47 provides a fuel heater 10 which may be manually adjusted to provide the optimum combustion temperature for the diesel fuel. Additionally, once the adjustable thermostat 47 is set at its predetermined adjustment, the adjustable thermostat 47 will regulate the fuel temperature by increasing or decreasing the flow of coolant through the fuel heater 10 according to the temperature of the heated fuel.

During testing of the fuel heater 10 it has been found that the flow of coolant may be modified to have the coolant flow into the fuel heater 10 through the coolant outlet 46 and out of the fuel heater 10 through the coolant inlet 26. Changing the flow of coolant through the fuel heater 10 provides a fully operational fuel heater 10 which is only slightly less efficient than the preferred embodiment described above. It is fully anticipated that this and other modifications may be made without departing from the scope of the present invention which is to be determined by the claims attached hereto.

In an alternate embodiment of the invention and as shown in Figs. 11 - 14, a top cover 212 is preferably constructed of aluminum and includes a fuel outlet 145,

SUBSTITUTESHEET a coolant outlet 146 and an adjustable thermostat 100. The adjustable thermostat 100 monitors the temperature of the fuel and limits the flow of coolant through the coolant outlet 146. The adjustable thermostat 100 includes a threaded adjusting screw 101 which extends inwardly into the top cover 212 to a location adjacent to the fuel outlet 145. The adjusting screw 101 is preferably constructed of aluminum or brass and consists of an adjusting knob 108; a threaded section 109; an O-ring and groove 110; a retaining collar 111 and a contact point 112. The O-ring and groove 110 and retaining collar 111 act in combination to prevent the heated fuel from passing out of the fuel heater 10 through the threaded opening for the adjusting screw

101. The contact point 112 is positioned adjacent to the heat transfer end 113 of the power pill housing

102. The power pill housing 102 is preferably constructed of a durable material such as a phenolic resin. The heat transfer end 113 of the power pill housing 102 extends across the fuel outlet 145 to allow the temperature of the heated fuel to be monitored by the adjustable thermostat 100. The second end of the power pill housing 102 is the retaining end 114 and is positioned adjacent to the fuel outlet 145. The retaining end 114 is held in position by a pair of O-rings and grooves, 115 and 116, which frictionally engage the interior of the heat insulator 103. The heat insulator 103 is preferably constructed of a phenolic resin and surrounds the retaining end 114 of the power pill housing 102 and is positioned adjacent to the fuel outlet 145. The heat insulator 103 is held in position by a pair of O-rings and grooves, 139 and 140, and prevents the transfer of heat from the heated fuel directly to the coolant by heating the top cover 212. A power pill 104 is located inside of the power pill housing 102. The power pill 104 is a commercially available temperature sensing device sold by Robertshaw Controls Company of Knoxville, Tennessee. The power pill 104 is designed for use in a variety of temperature ranges and consists of a power pill body 117 and a needle 118. The power pill body 117 expands or contracts according to the temperature of the heated fuel which causes the needle 118 to move in response to the temperature of the fuel. The needle 118 of the power pill 104 is in contacting engagement with the needle seat 119 on the insulating extension 105. The insulating extension 105 is preferably constructed of a phenolic resin and functions essentially as a means of transferring the movement of the power pill 104 to the piston 106. The extension end 120 of the insulating extension 105 is positioned within the retaining end 114 of the power pill housing 102. The collar 121 of the insulating extension 105 acts as a spacing means between the power pill housing 102 and the remaining elements of the adjustable thermostat 100. The second end of the insulating extension 105 is the piston contact end 122. The piston contact end 122 of the insulating extension 105 includes an equilibrium groove 123 which extends across the diameter of the piston contact end 122 and allows coolant to flow in the interior surface of the first end 124 of the piston 106.

The piston 106 is preferably constructed of stainless steel and consists of a first end 124; a second end 129; a pair of steel scraper O-rings and grooves, 125 and 128; a bleed port 127 a coolant channel 126 and a pressure channel 137. The first and second ends, 124 and 129 respectively, of the piston 106 are held in position by a pair of O-rings and grooves, 125 and 128 which facilitate the movement of the piston 106 by scraping the interior of the adjustable cylinder 107 to prevent the collection of grit or debris therein. The first end 124 of the piston 106 restricts the flow of coolant into the top cover 212 by partially blocking the flow of coolant from the annular coolant flow ring 73. A constant amount of coolant is allowed to flow into the top cover 212 by the bleed port 127 which allows coolant to flow from the coolant flow channel 126 into the pressure channel 127. This constant flow of coolant through the bleed port 127 equalizes the coolant pressure on the first and second ends, 124 and 129 respectively, of the piston 106 and lubricates the circumference of the piston 106. The piston 106 is enclosed within the adjustable cylinder 107. The adjustable cylinder 107 is preferably constructed of stainless steel and is frictionally held in position by an O-ring and groove, 135. The adjustable cylinder 107 includes a bottom coolant opening 133; a top coolant opening 124; a spring retaining groove 136 and a manual adjustment groove 138. A spring 130 is positioned in the spring retaining groove 136 to engage the interior surface of the second end 129 of the piston 106.

In operation, as shown in Figs. 11 - 14, the fuel flows into the fuel heater 10 through fuel inlet 59. The fuel then flows into the fuel distributor 60 and through the fuel passageways 61. The fuel passageways 61 force the fuel to flow horizontally into the lower fuel collection area 63. The fuel tubes 37 extend into the lower fuel collection area 63 a slight distance to prevent the fuel from flowing at varying rates into the individual fuel tubes 37. The fuel

BSTITUTE SHEE heater 10 optimally includes at least 16 fuel tubes 37 which act in combination to decrease the flow rate and pressure of the fuel as the fuel passes through the heat transfer chamber 64. Inside each fuel tube 37 is a tube insert 38 which spirals the fuel through the fuel tube 37 and thereby provides a more efficient transfer of heat from the coolant to the fuel. Once the fuel passes through the the fuel tubes 37, it passes into the top fuel basin 35. The top fuel basin 35 and the top cover 212 form the top fuel collection area 69 to collect the heated fuel and return the fuel to its original pressure and flow rate. From the top fuel collection area 69, the fuel flows across the power pill housing 102 and heats the power pill 104 of the adjustable thermostat 100. The fuel then flows out of the fuel heater 10; through the fuel outlet 145 and ultimately into the combustion chamber of the diesel engine.

The coolant enters the fuel heater 10 through the coolant inlet 26 located on the lower coolant ring 15. The coolant then flows through the lower coolant distribution passageway 66 and into the lower coolant passageways 29 located on the coolant distributor 16. Once the coolant flows through the lower coolant passageways 29 it enters the heat transfer chamber 64. In the heat transfer chamber 64, the coolant passes across the outer surface of the fuel tubes 37 to transfer the heat from the coolant to the fuel tubes 37 and heats the fuel. The coolant flows upwardly through the heat transfer chamber 64 so that the hottest coolant contacts the coolest fuel at the lower end of the heat transfer chamber 64; as the coolant and fuel pass into the upper end of the heat transfer chamber 64, the temperature of the coolant will decrease and the temperature of the fuel will have increased. The coolant passes from the heat transfer chamber 64 into the upper coolant distribution passageway 65 through the upper coolant passageways 28 located near the top end of the coolant distributor 16. The coolant flows upwardly from the upper coolant distribution passageway 65 into the annular coolant flow ring 73 located on the bottom surface of the top cover 212. The coolant then flows into the top cover 212 by passing through the bottom coolant opening 133 of the adjustable cylinder 107. After flowing through the coolant channel 126 and contacting the first end 124 of the piston 106, the coolant flows out of the top cover 212 by passing through the top coolant opening 134 of the adjustable cylinder 107 and into the coolant outlet 146.

The adjustable thermostat 100 may be manually adjusted by manually rotating the adjusting knob 108. When the adjusting screw 101 is rotated inwardly, the contact point 112 pushes against the power pill housing 102 to move the power pill 104 and insulating extension 105 toward piston 106. The piston contact end 122 of the insulating extension 105 pushes against the first end 124 of the piston 106 and causes the first end 124 to partially block the bottom coolant opening 133 of the adjustable cylinder 107. Additionally, if the fuel heater 10 is to be shut off, the adjustable cylinder 107 may be rotated by turning the manual adjustment groove 138 to the off position. When the manual adjustment groove 138 is in the off position, the coolant is prevented from entering the top cover 212 because the bottom coolant opening 133 is no longer in alignment with the annular coolant flow ring 73.

SUBST_ITUTESHEET In normal operation, the adjusting screw 101 is only used to fine tune the adjustable thermostat 100. Rotation of the adjusting screw 101 adjusts the thermostat to its optimum position according to the unique fuel and coolant flow rates of each engine; however, the adjustable thermostat 100 will automatically respond to fluctuations in the fuel and coolant temperatures during the operation of the fuel heater 10.

As the temperature of the fuel flowing through the fuel outlet 145 increases, the heat is transferred to the power pill housing 102. From the power pill housing 102 the heat is transferred to the power pill 104 which causes the power pill body 117 to expand. The expansion of the power pill body 117 causes the needle 118 of the power pill 104 to press against the needle seat 119 of the insulating extension 105. The insulating extension 105 then presses against the first end 124 of the piston 106. Meanwhile, the piston 106 is pushed in a constant manner in the opposite direction by the spring 130. As the pressure against the first end 124 of piston 106 increases, the first end 124 of the piston 106 begins to partially restrict the flow of coolant through the bottom coolant opening 133 and thereby decreases the coolant flow through the fuel heater 10 and ultimately decreases the heat transferred to the fuel.

As the temperature of the fuel decreases_/ the first end 124 of the piston 106 is returned to its normal position by presure from the spring against the second end 129 of the piston 106. The movement of the piston 106 is further regulated by the constant flow of coolant through the bleed port 127 and pressure channel

SUBSTITUTESHEET 137. By allowing a constant flow of coolant into the first and second ends, 124 and 129 respectively, of the piston 106, a sudden fluctuation in the flow rate or . pressure of the coolant will not force the piston 106 to move rapidly in either direction. The coolant in the first and second ends, 124 and 129 respectively, acts as a hydraulic cushion to slow the movement of the piston 106 until the coolant pressure on each side of the piston 106 is stabilized. Additionally, the use of the steel scraper O-rings, 125 and 128, to remove debris or grit from the interior of the adjustable cylinder 107 decreases the likelihood that the piston 106 will become stuck in the adjustable cylinder 107. Therefore, the adjustable thermostat 100 of the present invention is designed to operate in a safer manner than the presently available fuel heater thermostats.

HEET

Claims

WHAT IS CLAIMED:

1. A fuel heating attachment for heating fuel with - engine coolant, comprising

an elongate annular section forming an annular side wall upon which transverse top and bottom covers are attached,

an elongate coolant distributor within the annular section having coolant passageways therein and extending from the top cover to the bottom cover to,

a heat exchanger having top and bottom ends located inwardly from the coolant distributor and extending from the top cover to the bottom cover,

said heat exchanger including a plurality of fuel tubes which extend through a heat transfer chamber formed by the inner surface of the coolant distributor and the top and bottom ends of the heat exchanger,

said fuel tubes extending through said heat transfer chamber to enable the coolant to flow around the outer surface of the fuel containing fuel tubes to heat the fuel tubes and fuel.

a fuel inlet on the fuel heater for directing fuel from the fuel system into the fuel heater,

a fuel outlet for directing heated fuel from the fuel heater to the engine,

SUBSTITUTESHEET a coolant inlet on the fuel heater for directing coolant from the engine coolant system into the fuel heater,

a coolant outlet on the fuel heater for directing coolant from the fuel heater to the engine coolant system,

a temperature sensing means for monitoring the temperature of the heated fuel and regulating the flow of coolant through the fuel heater.

SUBSTITUTE SHEET

2. The fuel heater of claim 1, wherein the temperature sensing means includes a thermostat located in the top cover which is in a flow communicating relationship with the fuel and the coolant.

3. The fuel heater of claim 1, wherein the fuel tubes include a spiral insert for spiraling the fuel through the fuel tubes as the fuel passes through the heat transfer chamber.

4. The fuel heater of claim 1, wherein the fuel tubes extend upwardly from the bottom end of the heat exchanger to the top end of the heat exchanger to enable the coolant to flow across the outer surface of the fuel tubes as the coolant flows through the heat transfer chamber.

5. The fuel heater of claim 1, wherein the fuel tubes of the heat exchanger extend downwardly beyond the bottom end of the heat exchanger into a fuel collection area formed by the bottom end of the heat exchanger and the bottom cover.

6. The fuel heater of claim 1, wherein the bottom cover further comprises a fuel inlet and a fuel distributor for evenly distributing the fuel into the fuel collection area.

7. The fuel heater of claim 6, wherein the bottom cover further includes a condensation plug for removing condensation from the fuel heater.

8. The fuel heater of claim 1, wherein the elongate annular section is comprised of upper and lower coolant rings.

9. The fuel heater of claim 8, wherein the lower coolant ring includes a coolant inlet, and in combination with the coolant distributor, forms a coolant distribution passageway for directing coolant into the heat transfer chamber through the coolant passageways.

10. The fuel heater of claim 1 wherein the top cover includes a fuel outlet, a coolant outlet and a thermostat in flow communication with the heated fuel and coolant.

11. The fuel heater of claim 10, wherein the top cover in combination with the top end of the heat exchanger forms a fuel collection area for the collection of heated fuel after the fuel passes through the fuel tubes.

12. The fuel heater of claim 2, wherein the temperature sensing means is an adjustable thermostat for manually adjusting the flow of coolant through the fuel heater.

13. The fuel heater of claim 1, wherein the elongate annular section includes a mounting bracket mounted thereon for mounting the fuel heater in the engine compartment.

SUBSTITUTESHEET

14. The fuel heater of claim 1 wherein

said temperature sensing means is in contacting relation with the first end of a coolant flow restricting piston,

said piston having a second end in contacting relation with a pressure means wherein said temperature sensing means and said pressure means assert opposing forces against said piston and said piston in response to an increase in force from said temperature sensing means will restrict the flow of coolant through the fuel heater, and

said piston further having a bleed port therein to allow coolant to flow to said first and second ends of said piston.

15. The fuel heater of claim 14, wherein the temperature sensing means is partially enclosed by a housing which is in flow communication with the heated fuel of the fuel heater and the temperature of the fuel is transmitted through the housing to the temperature sensing means.

16. The fuel heater of claim 15, wherein said housing is partially enclosed by an insulating ring positioned adjacent to the heated fuel to prevent the transfer of heat from the fuel directly to the piston.

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17. The fuel heater of claim 14, wherein the position of the temperature sensing means may be manually adjusted by an adjustable screw in contacting relation with said temperature sensing means.

18. The fuel heater of claim 14, wherein the piston is partially enclosed in a piston housing and said piston includes a cleaning means to prevent the accumulation of debris between the piston and said piston housing.

^JiSTlTUTESHEET

19. The fuel heater of claim 1, wherein the temperature sensing means comprises

a manually adjustable screw having inner and outer ends,

said inner end in contacting relation with a temperature sensing housing,

said housing being in flow communication with the heated fuel from the fuel heater,

said housing further being in heat transferring relation with the temperature sensing means for the transfer of heat from the fuel to the temperature sensing means,

said temperature sensing means being responsive to changes in the temperature of the fuel and in contacting relation with a coolant flow restricting piston wherein said temperature sensing means expands in response to increases in the temperature of the fuel and contacts the piston to cause the piston to restrict the flow of coolant through the fuel heater.

20. The fuel heater of claim 19 wherein

the piston has first and second ends,

said second piston end is in contacting relation with a pressure means,

said pressure means in combination with an adjustable cylinder operates to oppose the contacting relation of the temperature sensing means against the first end of said piston.

21. The fuel heater of claim 20 wherein said adjustable cylinder includes top and bottom coolant openings therein and said adjustable cylinder is rotatable to block the flow of coolant through the fuel heater.

22. The fuel heater of claim 19, further comprising

first and second ends on said piston wherein said first end is in contacting relation with the temperature sensing means,

said second end is in contacting relation a pressure means wherein said pressure means is biased against the contact of the temperature sensing means, and

said piston further having a bleed port and coolant channel in continuous flow communication with the first and second ends of said piston to hydraulically control the movement of said piston.

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