US3882900A

US3882900A - Pressure sensing and responding device

Info

Publication number: US3882900A
Authority: US
Inventors: Horace A Williams
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-06-04
Filing date: 1973-06-04
Publication date: 1975-05-13
Anticipated expiration: 1992-05-13

Abstract

A device is disclosed which includes in combination a pressure sensing valve and a linking mechanism responsive thereto. The pressure sensing valve includes a housing adapted at one end for connection to a pressurized engine coolant system. The same end of the housing also contains a flexible diaphragm which divides that end of the housing into two chambers. The other end of the housing is cylindrically bored to accommodate a slidable spring biased porous piston. A diaphragm face plate, in contact with the flexible diaphragm, is adjustably mounted to the slidable piston such that as the diaphragm is expanded, the piston is slidably moved within the bored or cylinder portion of the housing. Movement of the piston exposes and/or blocks a combination of ports opening into the cylindrical bore. The outlet end of one of the ports leads to a sump while another outlet leads to a pressurized liquid carrying line connected to a linking mechanism positioned between the fuel injector''s governor and the foot throttle control. Port selection is controlled by the location of the piston within the housing. The piston within the housing is actuated by a positive pressure exerted on the flexible diaphragm by the heated coolant.

Description

United States Patent Williams May 13, 1975 PRESSURE SENSING AND RESPONDING [57] ABSTRACT DEVICE A device is disclosed which includes in combination a [76] Inventor: Horace A. Williams, 6123 Rodeo presslfre Sensing valve and a linkillg t Ln Salt Lake City, Utah 84121 sponsive thereto. The pressure sensmg valve includes a housing adapted at one end for connection to a pres- Filed: June 4, 1973 surized engine coolant system. The same end of the [211 App]. NOJ 366,450 housing also contains a flexible diaphragm which divides that end of the housing mto two chambers. The other end of the housing is cylindrically bored to ac- [52] US. Cl. 137/625.34; 251/613; 251/368 commodate a slidable Spring biased porous piston. A [51] Int. Cl. Fl6k 11/07; Fl6k 51/00 diaphragm face plate, in Contact with the flexible i [58] Field of Search 251/613, 368; 137/269, phragm is adjustably mounted to the slidable piston 137/625-33 62534 625-37 such that as the diaphragm is expanded, the piston is slidably moved within the bored or cylinder portion of References C'ted the housing. Movement of the piston exposes and/or UNITED STATES PATENTS blocks a combination of ports opening into the cylin- 347915 8/l886 Blackburn 251/368 x drical bore- The Outlet end of one Of the ports leads to 2,493,449 1/1950 Fitch .3 X a sump while another outlet leads to a pressurized liq- 2,868,483 1/1959 Krueger.... .3 X uid carrying line connected to a linking mechanism 3,070,124 12/1962 Fitzpatrick l37/625.34 X positioned between the fuel injectors governor and 3,363,412 1/1968 Fischer et a]. 251/613 X the foot throttle control. p Selection is controlled 3,406,702 l0/l968 Jenney l37/625.34 X y the location of the piston within the housing. The 3,466,950 9/1969 Mummert 137/6253? X Primary Examinerl-Ienry T. Klinksiek Attorney, Agent, or FirmRichard F. Bojanowski piston within the housing is actuated by a positive pressure exerted on the flexible diaphragm by the heated coolant.

12 Claims, 8 Drawing Figures PATENTEBHAYIBISYS 3.882.900

sum 30$ 4 PATENIED M 1 1 1 3; 882.90 0

SBEEI t Of 4 {/8 m :SUMP 74 7 v- |75& I44 l43 SUMP on. PUMP 34 GOVENOR FOOT THROTTLE we I00 LINKAGE COOLANT PRESSURE Y on. SUMP FIG. 7

lBZ

OIL PUMP 1 -COOLANT PRESSURE SUMP lF/G. 8

1 PRESSURE SENSING AND RESPONDING DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention is directed to a pressure sensing and responsive device for controlling the amount of fuel introduced into an internal combustion engine and particularly to a pressure-type valve responsive to pressure changes of an internal combustion engine's coolant and an extendible linking mechanism actuatable by said pressure-type valve.

2. State of the Art All diesel engines are equipped with pressurized lubrication and coolant systems. The former supplies oil to all main connecting rods and cam shaft bearings as well as to other movingparts within the engine. In operation a gear type pump is normally used to draw oil from the sump or oil pan through an intake screen and oil filter and finally on to an oil cooler. From the oil cooler, the oil flows through passageways that connect oil galleries in the cylinder block and cylinder heads for distribution to the bearing and rocker arm mechanisms as well as to other functional parts of the engine.

I The coolant used in the engine coolant system is normally circulated through the engine by a centrifugaltype pump. Heat is removed from the coolant by a heat exchanger or radiator. Flow of the coolant through the radiator is controlled by a valve actuated by a thermostat. Although the thermostat is capable of restricting flow of the coolant during the period when the engine is heating up, the thermostat cannot prevent the engine from overheating when adverse operating conditions or a malfunction occur. To advise the vehicles operator of an impending malfunction in the engines cooling or lubrication systems, all engines are equipped with gauges, lights and other signaling and/or warning devices.

Generally, these signaling or warning devices comprise a temperature-sensing means, such as a thermocouple; which measures and reports the engines coolant and oil temperatures at a particular point in the system. If a malfunction occurs, the reported temperature is, in most cases, many degrees above or below the actual temperature. This lag in temperature reporting can cause serious damage to the vehicles engine.

In addition to warning devices, the vehicle is also normally equipped with instruments to advise the operator of existing engine conditions prior to start up. Unfortunately though, a large percentage of the operators will pay little attention to these instruments and will operate an engine, such as a diesel, at full capacity before the engine coolant temperature and oil pressure reach proper operating levels. This type of use produces an unnecessary strain on the engine, inefficient burning of the engines fuel and the emission of excessive amounts of black exhaust which contributes to the pollution of the atmosphere in the form of unburnt hydrocarbons and nitrogen oxide.

Normally a diesel is also provided with an electrical alarm system in conjunction with an electrical engine shutdown system. If an abnormal condition occurs, the engine will be automatically shut down and an alarm bell will be sounded to advise the operator of an existing malfunction.

In addition to electrical systems, various mechanical shutdown systemshave also been proposed. In each instance, though, the system is actuated by an electrical switch which is activated by a change in the vehicles oil pressure, fuel pressure and/or coolant temperature.

Systems of the type above described have generally been unsatisfactory as they are for the most part unreliable, are easily overridden and are costly to install and maintain. Another problem has been that it is generally unsatisfactory to have a complete and unexpected engine shutdown as the operator may find himself in a precarious situation which could be further compounded if the engine was totally shut down at that particular time. Automatic shutdown systems on diesels are especially dangerous when the vehicle is traveling over. mountainous terrain or on an interstate highway where violations of minimum operating speeds could be perilous to not only the operator but also to others traveling the interstate.

In addition to the systems above described, the diesel engines are also equipped with some type of governor for automatically varying the amount of fuel injected into the engine cylinder whenever fluctuations in load and/or changes in operating terrain are encountered. Generally the governor is part of themechanical linkage connecting the foot throttle with the fuel injectors. The purpose of the governor is to maintain a near constant engine speed under normal operating conditions and thereby minimize excessive engine strain.

OBJECTS OF THE INVENTION It is therefore an object of this invention to provide a pressure sensing and responsive system which avoids the disadvantages and problems aforementioned.

Another object is to provide a type of fail-safe device and system which is capable of responding to changes in oil and coolant pressures whenever a pressure line malfunction occurs which would have an adverse affect upon the vehicles operation.

Another object is to provide a device which is capable of providing a rapid response to an increase or loss in oil and/or coolant pressure.

Still another object of this invention is to provide a sensing system which not only advises the operator of malfunctions but also is conducive to optimizing fuel consumption and thereby reducing, if not overcoming, excessive emissions of contaminants from the engines stacks.

Another object is to provide a system which is capable of reducing vehicle speed whenever a malfunction is detected in the lubrication or coolant systems.

Another object is to provide a device which prevents operation of the vehicle during startup until such time that the vehicles recommended operating coolant temperatures and oil pressures are attained.

Still another object of this invention is to provide a system for rapidly detecting changes in temperature of an engines coolant by sensing the coolants corresponding change in pressure.

SUMMARY OF THE INVENTION These and other objects and advantages are achieved by the pressure sensing and responding device which comprises an engine coolant pressure sensing means and a means for transmitting a signal, in response to the coolant pressure, to a pressure responsive linking means which automatically alters the amount of fuel introduced into an internal combustion engine.

More specifically, the device of this invention includes a pressure responsive valve comprising a housing having a slidable porous piston carried in one end thereof. The other end of the housing contains in fixed position a flexible diaphragm which divides the housing into two pressure chambers. When a pressure change occurs in one of the chambers, the diaphragm is expanded and the piston, which is connectably attached to the diaphragm is slidably moved. As the piston moves, various ports are simultaneously blocked and- /or exposed to permit a pneumatic pressure signal to be transmitted to a pressure responsive, extendible linking means positioned intermediate the fuel injection systems governor and foot throttle control. When the pressure signal falls below a preselected minimum, the amount of fuel injected into the engine is reduced by an automatic shortening or lengthening of the pressure responsive linking means. Preferably the pneumatic pressure signal is a branch of the engines closed pressurized oil lubrication circuit. With this system any malfunction occurring in the engines pressurized coolant or lubrication systems will be detected and will automatically reduce the amount of fuel introduced into the engine, causing a reduction in engine speed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side cross section of the pressure responsive valveof this invention.

FIG. 2 isan exploded view of the pressure responsive valve shown in FIG. 1.

FIG. 3 is a side cross section of a pressure responding linking mechanism.

FIG. 4 is an exploded view of the linking mechanism shown in FIG. 3.

FIG. 5 is an isometric view of a linking mechanism which is installed internally and is normally submerged in oil.

FIG. 6 is an exploded view of the linking mechanism shown in FIG. 5 with portions shown in cross section.

FIG. 7 is a schematic showing the working relationship between the pressure responsive valve of FIGS. 1 and 2 and the linking mechanism shown in FIGS. 3 and 4.

FIG. 8 is a schematic showing the working relationship between the pressure responsive valve of FIGS. 1 and 2 and the linking mechanism shown in FIGS. 5 and 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIGS. 1 and 2, the pressure responsive valve 10 includes a bell-shaped housing 12 and a lower housing member 16. A diaphragm 18 extends between the two housings and is held in position by bolts 20 passing through threaded openings in the

peripheral lips

24 and 26 which extend outward from the

housings

12 and 16.

The extended diaphragm l8 separates the two housings to form a pressure chamber 28 and a breathing chamber 30. The latter is maintained at ambient pressure by a breather opening 32. The lower housing 16 is provided with a threaded opening 34 for receiving a threaded nipple (not shown) for directing an engines pressurized coolant into the pressure chamber 28. A centrally bored stop member 40, having spaced-apart ports 42, is positioned over the outlet end 36 of opening 34 and directs the pressurized coolant into the pressurized chamber 28 via a central opening 41 in communication with outlet ports 42. The other end of the stop member has a threaded shaft 43 extending outwardly therefrom and through an annular opening in the diaphragm 18. Within the breathing chamber 30, the diaphragm 18 is in contact'with an annular plate 44 having a central opening through which the threaded shaft 43 passes. An adjusting nut 48, fitted over the threaded shaft 43, holds the annular plate 44 flush against the diaphragm 18.

A porousvpiston member 50 having its end sections SOaand 50b separated by an annular groove or space 52 is slidably carried within the cylinder section 54 of the bell-shaped housing 12. One end of the piston member 50 also contains a threaded opening 56 which engages the threaded shaft 43 of stop member 40 and held in locked position thereon by a threaded locking nut 62. The end sections 50a and 50b of the porous piston are fitted with O rings 58 and 60 for sealing against the cylinders inner wall. The end face of the porous piston 50 is adapted with a bored portion 64 to receive a coil spring 66 which continuously urges the piston toward and against the inner wall of the lower housing member 16. The compression of the spring is regulated bya threaded plug 68 fitted in the threaded end of the cylinder 54. To assist in turning the plug, a lateral slot 69 is provided. A locking nut 70 fits over the threaded plug 68 locking the plug in position after the desired spring compression has been achieved.

The outside wall 72 of the cylinder section of the bell housing 12 contains a threaded liquid inlet opening 74 fitted with an adapter 76 which in turn is connected to a line leading to the engines oil pump (FIGS. 7 and .8). On the other side of the cylinders outlet wall a threaded liquid outlet opening 78 is provided which also is fitted with an adapter 80 connected to a line line leading either to sump or to the linking mechanism as depicted in FIGS. 7 and 8. The inlet opening 74 intersects a longitudinal channel 82 bored into the cylinder wall of the housing. A first transverse intersecting channel 84 is provided and connects the longitudinal 82 channel with the cylinder section 54 to provide an interconnectirig passageway between the cylinder and the longitudinal channel. A second transverse intersecting channel 86 positioned apart and parallel to the first transverse intersecting channel 84 connects the cylinder with the longitudinal channel 82. The distance between the two transverse intersecting channels is slightly less than the height of the pistons end section 50a.

Bored outlet opening 78 passes partially through the cylinder wall and intersects a second longitudinal channel 88 and, like the first longitudinal channel 82, has two

transverse intersecting channels

90 and 92 which connect the cylinder section 54 with the longitudinal channel 88.

lntersecting channels

86 and 92 are positioned opposite each other so that both channels are either exposed or blocked at the same time depending on the position of the piston 50 within the cylinder section 54.

lntersecting channels

84 and 90 are positioned such that when the diaphragm is relaxed, i.e., at ambient pressure, both channels open into the annular groove 52 permitting a direct flow of pressurized oil from the inlet 76 to the outlet 78 which leads to sump. In some cases, depending on the design of the linking mechanism and/or the use of the pressure sensing valve, the outlet 78 may lead elsewhere than sump.

At or near the end of thebell-shaped housing 12, another outlet channel 94 is provided which connects with the longitudinal channel 82. A line 96 connects channel 94 with one of the linking mechanisms shown in FIGS. 3 through 6 interposed'bet'ween the governor ,of the engines fuel injection system and the engines throttle. In cases where the pressure sensing valve is connected to a linking mechanism that is mounted within the engine (FIGS. 5 and 6), channel 94 is normally closed and outlet 78 is connected directly'to the linking mechanism. A more thorough discussion of the various types of linking mechanisms and their applications will subsequently follow.

An important feature of this invention is that the pistons be porous. That is, the piston must contain pores of such size and diameter that a portion of the pressurized lubricating oil passes into the piston s pores and is retained therein. It has been found that when a nonporous piston or one which is not capable of selflubrication is used, piston sidelocking and/or scoring are more likely to occur. 1 In FIGS. 3 and 4, an extendible linking mechanism is depicted for automatically altering the amount of fuel that can be introduced into an engines cylinder. The linking mechanism is inserted as part of the linkage connecting the governor and the throttle control systern. Since the linking mechanism is extendible in length it is capable of automatically adjusting the linkage between the governor and the throttle control in direct response to changes in coolant and/or oil pressure. In essence, therefore, the linking mechanism can be described as being an extendible mechanical linkage responsive to direct or indirect changes in pressure. For purposes of this invention, the terms .mechanical linking means or extendible linking mechanism are understood to mean a mechanical device for automatically varying the length of the linkage between the governor and the throttle control in response to a change in pressure of a control fluid, such as oil, from the engines lubrication system. In some areas, extendible linking mechanisms are referred to as a robe.

In addition, the linking mechanism canbe adapted so that it can be used in either a wet or dry system. If the linking mechanism is'used'in a wet system, it is normally enclosed in a housing and is contained within a lubricating fluid. Such a linking mechanism is shown in FIGS. 5 and 6 and is normally used on diesels manufactured by companies such as Caterpillar Tractor Co.

When the linking mechanism is adapted for use in a dry system, the linking mechanism is externally located and is not submerged in a lubricating fluid-Such linking mechanisms would be used on diesels manufactured by" such companies as Cummins, DetroitDieseI or in gasoline-type automotive engines such as those produced by General Motors, Ford or Chrysler Corporations. One embodiment of a dry mechanical linkage is shown in FIGS. 3 and 4.

As shown in- FIGS. 3 and 4, the extendible linking mechanism 100 includes a housing 101 formed by abutting the base sections of two identical bell-shaped

members

102 and 104 respectively. The bell members are separated by a distribution disc 106 containing ,an annular groove 108 cut into both-facesvofthe disc. A bored vertical channel 110 extends downward from .the edge of the disc and intersectsboth of theannular grooves 108 by means of a horizontal channel l11-to provide an intersecting passagewayfor {thedistribution threaded ..c ap or bolt 109 Centrally and inwardly from v .the annularl' groove leach face of .theidisc contains a concave indentatibn lll flexible Neoprene dia- 'tion disc, theNeoprene diaphragms and the peripheral J outward-extending flanges 12 0 and 122 of the bell housings 102 and l04 respectively.

The outer end of each bell membercontains an opening 1j24 and. 126 for receiving a slidable rod 128 and I 130 havinga'convex-shaped

head

132 and 134 which 7 matches a curvatu rethe concave indentation carried by thedistributiondisc 10 6. The

convex heads

132 and 134 are continually urged into the concave indentations 112 by means of a

coil spring

136 and 138 seated against a shoulder 140 formed within each of the

bell members

102 and 104. The rods are held in a fixed position by locking

nuts

141 and 143. As shown, the tension on the spring is sufficient to urge the flexible diaphragm into the concave indentation. The peripheral flanged ends and 122 of the bell members contain horizontally bored constricted channels 142 which intersect with vertical channel 110. The constrictions in channels 142 permit the pressurized oil to enter or exit the vertical channel at a predetermined controlled rate. These constrictions are such that a convenient time delay is built into the linkage system. This prevents the feeding of excessive amounts of fuel into the engine during acceleration and thereby avoids flooding- I Theconstricted horizontal channels 142- arefitted with adapters 144 which in turn are connected to a tubular line 143. The tubular lines are joined to'a pressurized oil system (see FIGS. 7 and 8) so that a portion of the pressurized oil will flow through the linesand into the vertical channel for distribution into the annular grooves formed on both faces of the distribution disc 106. As the oilpressure is gradually increased, the flexible diaphragms are urged outwardly forcing the springloaded rods outwardly and away from each other. The ends of each rod 128 and are threaded to facilitate connecting the linking mechanism between the governor and the throttle control.

As long as the pressure of the coolant is betweenfor example 4 and 18 psi, and preferably between 7.and 15 psi, the mechanical linkagebetween the governor and the throttle control is relaxed as is shown in FIGS. 3 and 4.-In the relaxed position the linkage between the governor and throttle control is capable of being extended by as much as one-quarter of an inch. With the linking mechanism in its extended position, the fuel injection system functions in a normal manner, that is, fullpower is available to the operator. However, with the linking mechanism in a relaxed position, the operator is able to obtain an engine speedapproximating only a fast idle even if the accelerator is fully depressed. Thisof course prevents operation of the diesel until manufacturer-recommended operating pressures and temperatures are reached.

1 The mechanical linkage shown generally in FIGS.

Sand 6 by numeral comprisesv a housing 152 having a link rod 153 connected to and extending outward therefrom. An opening 154 is provided in the end of thelink rod forinterconnecting with the'linkage be- ,tweenthe governor and the throttle 'controlof a diesel .engine. The inner portion of the housingis bored to ac- ,cornmodate aporous piston-155. Extending outward from the piston is a rod 156 having an opening 157 in its outer end. A coil spring 158 encircles the rod and is held under compression within the housing by bushing 159 and a snap ring 161.

Housing 152 also includes internally threaded openings 162 and 163 to which pressurized oil lines are connected. Restricted port 164 and partially restricted port 165 are also provided to return the oil introduced into the housing through the openings 162 and 163 to sump. Since restricted port 165 is larger than port 164, the pressurized oil exiting through port 165 exits at a rate faster than through port 164. Since the oil exiting through port 164 moves at a slower rate than through port 165, a back pressure is created which is sufficient to overcome the tension of coil spring 158.

The housing also contains a chamber 170 separated from the pistons cylinder 171 by a shoulder 172. An O-ring 173 is carried along the peripheral edge of the piston to create a floating environment for the piston within the housing and to separate the two oil chambers one from the other. In addition ports 162 and 163 are sufficiently constricted to create a time delay which prevents excessive amounts of fuel from being introduced into the engine during acceleration. Operationally, the pressure sensing valve 10 is connected to the extendible linking mechanism either 100 or 150 by a seriesof lines as shown in the schematics of FIGS. 7

and 8.

In FIG. 7, the pressure sensing valve is connected to an external or dry linking mechanism by a pressurized oil line 175. Pressurized oil enters liquid inlet 74 through line 176 and, depending on the position of piston 50 within the cylinder 54, passes to either line 175 or line 177 leading to sump. Pressurized coolant enters the pressure sensing valve through inlet 34 via line 178.

Prior to engine startup, the porous piston 50 is in a relaxed position as shown in FIG. 1. In this relaxed position, intersecting

channels

84 and 90 are open permitting the pressurized oil to enter through inlet 76 and pass into the annular space 52 located between the pistons end sections 50a and 50b. The oil then flows into intersecting channel 90 and longitudinal channel 88 and out through the liquid outlet 78 to sump.

As the engine warms up and the coolant is heated, a positive pressure is exerted by the coolant on diaphragm 18 forcing the spring-loaded piston to move toward the end of the cylinder and against spring 66 closing channel 90. Channels 89 and 90 remain closed at normal operating coolant temperatures and pressures. Under normal operating conditions the oil is rerouted into the longitudinal channel 82 and out through intersecting channel 94 and line 96 to the linking mechanism shown in FIG. 3. At a predetermined coolant pressure (determined by the coolants temperature), the linking mechanism will become extended and will permit the fuel injection system to operate in. a normal fashion. However, if the coolant temperature increases or decreases above or below normal, the piston is repositioned within the cylinder and the pressurized oil is rerouted through other channels bored in the valve. If, for example, the temperature of the coolant rises above normal operating temperatures so that a greater pressure is exerted on the diaphragm, the piston 50 will compress the spring 66 still further and uncover intersecting

channels

86 and 92. This will then direct the oil once again to sump via channel 92 and concomitantly therewith gravitationally drain the pressurized oil from the linking mechanism through

channels

94 and 86, releasing the pressure thereon. When the oil pressure on the linking mechanism is released, it will automatically retract and thereby reduce the amount of fuel introduced into the engine, slowing the engine speed to that approximating a fast idle. I

When the engine is shut down and the coolant temperature approaches ambient temperature, the piston retreats, opening and closing ports in reverse manner until the piston returns to the position shown in FIG. 1.

When the pressure sensing valve 10 is connected to a wet or internal linking mechanism 150 (FIGS. 5 and 6) as shown in FIG. 8, the pressure sensing valve is somewhat modified. As shown, the outlet 94 is capped and line 180 leads from outlet 78 to the linking mechanism 150 rather than to sump as shown in FIG. 7. The coolant enters the pressure sensing valve through opening 34 and line .181 while the pressurized oil enters inlet 74 through.line 182.

A second pressurized oil line 183 continuously carries pressurized oil to the linking mechanism through inlet 163. Since the linking mechanism is carried within a sump housing filled with oil, the oil passes through constricted

openings

164 and 165 to sump.

Prior to engine start up, piston 155 is being urged by spring 158 against shoulder 172 located within cylinder 170. In this position full throttle is available to the operator for startup. Almost immediately after startup or as soon as the oil pump has built up a preselected oil pressure sufficient to overcome the tension of spring 158, the piston 155 is slidably moved within the cylinder 17] extending rod 156 When the linking mechanism is in the extended position, the operator is unable to accelerate beyond a fast idle.

As the engine warms up and the coolant reaches a temperature of between F and F, a sufficient pressure is exerted on the diaphragm 18 of the pressure sensing valve 10 forcing the spring loaded piston to move against the spring 66 closing channel 90. When this occurs, -the oil passing to the linking mechanism 150 through line 180 is blocked and the oil in chamber 170 of the linking mechanism is slowly drained to sump through constricted opening 164. As the pressure in chamber 170 is reduced the piston is slowly moved toward the shoulder 172 by spring 158 and by the pressurized oil entering the cylinder 171 through inlet 163. Since

openings

164 and 165 are constricted a built in throttle delay or time delay is provided which retards full fuel injection when the engine is accelerated. This aids in reducing acceleration exhaust smoke and helps to improve fuel economy.

It should be noted that constriction 165 is somewhat larger than constriction 164 and thus permits a sufficiently high oil back pressure to build up in chamber to overcome the spring 158 and the oil back pressure in cylinder 171. This occurs on startup and if the engines coolant temperature exceeds a preselected maximum. When the coolant temperature rises above the normal operating range so that a higher pressure is exerted on the diaphragm 18, the piston 50 will compress the spring 66 still further and uncover

channels

86 and 92. This will then open line permitting oil to enter chamber 170 forcing the piston 155 to slidably move outward extending the linking mechanism 150 in the same manner it did on startup. When this occurs, the speed of the engine is reduced to that of a fast idle,

preventing the operator from operating the vehicle at high speeds when the engine is overheating.

If desired, the linking mechanism may be adapted with an overriding system which is capable of overriding the pressure sensing valve. This can be conveniently accomplished by attaching an operator-actuatable pressurized fluid line to the linking mechanism which, when actuated, will force the piston in a direction which will provide immediate full fuel injection.

Although the inventive concept described herein refers to specific features, such specificity is intended forexample only and is not to be construed as limiting this invention as it is intended that the invention be limited only by the claims appended hereto. It is also evident that certain changes, modifications and variations could be readily made without departing from the spirit and scope of this invention.

I claim:

1. A pressure sensing valve comprising a'valve housing, a pressure sensing means carried within said housing, a porous valve means responsive to said pressure sensing means and a series of ports connected to fluid carrying passageways bored within said housing, said ports being exposed or covered by said valve means as pressure changes are sensed by said pressure sensing sending means.

2. The valving device of claim 1 wherein the valve means comprises a porous piston slidably carried within said housing.

3. The valve device of claim 2 wherein said piston is continually urged towards and in contact with said pressure sensing means.

4. The valving device of claim 3 wherein said porous piston is continuously urged toward said pressure sensing means by a spring biasing means.

5. The valving device of claim 1 wherein the pressure sensing means includes a pair of pressure chambers separated by a flexible diaphragm.

6. The valving device of claim 5 wherein one of said pressure chambers is maintained at ambient pressure.

7. The valving device of claim 5 wherein said pressure chamber is maintained at ambient pressure and the other pressure chamber is adapted to accept pressures greater than ambient.

8. The valving device of claim 1 wherein said valve means comprises a porous piston slidably carried within said housing and said sensing means includes a pair of pressure chambers separated by a flexible diaphragm.

9. The valving device of claim 8 wherein said porous piston is being continually urged against said diaphragm by a spring biasing means.

10. The valving device of claim 9 wherein said porous piston has an intermediate cross sectional area less than the cross sectional area of each of its ends.

11. The valving device of claim 8 wherein the compression of said spring biasing means is capable of being varied by an adjustable means.

12. The valving device of claim 1 wherein one of said pressurized fluid-carrying passageways is connected to a pressure responsive linking means having a length which may be increased or decreased depending upon the pressure exerted on said linking means by a fluid carried by said pressurized fluid carrying passageways.

Claims

1. A pressure sensing valve comprising a valve housing, a pressure sensing means carried within said housing, a porous valve means responsive to said pressure sensing means and a series of ports connected to fluid carrying passageways bored within said housing, said ports being exposed or covered by said valve means as pressure changes are sensed by said pressure sensing sending means.