FUEL PRESSURE CONTROL SYSTEM FOR AN INTERNAL COMBUSTION ENGINE

D ESC RI PTI O N BACKGROUND OF THE INVENTION

[Para 1 ] The present invention is generally directed to a fuel pressure regulator for a motor vehicle. More particularly, the present invention is directed to a programmable electronically controlled fuel pressure regulator.

[Para 2] Fuel pressure regulators have been previously proposed. Spring based pressure regulators are known that use spring force to control a valve providing fluid communication to a return fuel line. However, the fuel pressure regulators of the prior art do not allow for an efficient method of varying the regulated fuel pressure. There is a need for a design that overcomes the shortcomings of the related art. The present invention fulfills these needs and provides other related advantages.

SUMMARY OF THE INVENTION

[Para 3] The present invention is directed to a fuel pressure control system for an internal combustion engine. The system comprises a fuel regulator block for a fuel injector. The fuel regulator block has an internal valve port and a diaphragm for regulating fuel pressure within the fuel regu lator block. The system fu rther comprises a means for mechanically adjusting a position of the diaphragm in the fuel regulator block. A microcontroller is operatively connected to the diaphragm position adjusting means and programmed to selectively open or close the internal valve port. The microcontroller preferably has multiple sensors to sense engine conditions, including fuel pressure, vacuum pressure, and/or oxygen content. The fuel regulator block preferably comprises a base unit having an inlet port and an outlet port with the internal valve port there-between.

[Para 4] A resilient diaphragm spring exerts a biasing force against the diaphragm. An adjustment screw engages the resilient diaphragm spring and adjusts the biasing force against the diaphragm. In one preferred embodiment, the diaphragm position adjusting means comprises a pneu matic pressure regu lator disposed on the fuel regulator block for exerting positive or negative pressure on the diaphragm. In this preferred embodiment, the adjustment screw establishes a base operating position of the diaphragm within the fuel regu lator block. In another preferred embodiment, the diaphragm position adjusting means comprises a motor disposed on the fuel regulator block. The motor has an output shaft mechanically coupled to a spring locator on the resilient diaphragm spring to increase or decrease the biasing force of the resilient diaphragm spring against the diaphragm.

[Para 5] The diaphragm is configured to seal or allow varying amou nts of fuel to pass through the valve port. The fuel regulator block may comprise a two- sided base unit having an inlet port and an outlet port, with a first valve port and a second valve port there-between. In the two-sided base unit, the fuel regulator block comprises a first diaphragm operatively associated with the first valve port and a second diaphragm operatively associated with the second valve port. The first diaphragm and second diaphragm are configured to seal or allow varying amounts of fuel to pass through the first valve port and second valve port respectively.

[Para 6] Also in this two-sided base unit, the diaphragm position adjusting means comprises a pneumatic pressure regulator disposed on a first side of the fuel regulator block, and a motor having a threaded output shaft disposed on a second side of the fuel regulator block. The pneumatic pressure regulator exerts positive or negative pressure on the first diaphragm, and the threaded output shaft increases or decreases a biasing force exerted by a resilient diaphragm spring against the second diaphragm.

[Para 7] Other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[Para 8] The accompanying drawings illustrate the invention. In such

drawings: [Para 9] FIGURE 1 is a block diagram illustrating configuration of an electronically controlled fuel pressure regulator in relation to a motor vehicle engine;

[Para 1 0] FIGURE 2 is an exploded view of an electronically controlled, pneu matic adjustable fuel pressure regulator;

[Para 1 1 ] FIGURE 3 is an exploded view of an electronically controlled mechanical fuel pressure regulator;

[Para 1 2] FIGURE 4 is an exploded view of a dual stage electronically controlled pneumatic and mechanical fuel pressure regulator of the present invention;

[Para 1 3] FIGURE 5 illustrates a fuel pressure regulation circuit in the base unit; and

[Para 1 4] FIGURE 6 illustrates a fuel pressure regulation circuit for the dual base unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[Para 1 5] FIGURE 1 illustrates a basic block diagram of an inventive fuel pressure regulator 1 0, 40, 72 installed in connection with an engine 42 and microcontroller 44. The regulator 40 is in line with a fuel inlet on the engine 42 and responsive to signals from the microcontroller 44. The microcontroller 44 senses various engine conditions, including but not limited to vacuum

manifold, oxygen content, and fuel pressure, to mention a few. The

microcontroller 44 has or is in electronic communication with a manifold vacuum sensor 46, a lambda or oxygen sensor 48, and a fuel pressure sensor 50. The lambda or oxygen sensor 48 is preferably a wide band zirconia sensor or similarly configured device. The lambda sensor 48 may also comprise a basic zirconium dioxide or zirconia sensor, or a titania made of titanium dioxide. The regulator is used by the system to control the pressure of the fuel entering the engine 42.

[Para 1 6] The microcontroller 44 preferably has a switchable lead such that voltage is supplied when the ignition key is in the on position and not supplied when the ignition key is in the off position. The microcontroller 44 may also be connected to a twelve volt non-switchable system. In this instance, the microcontroller 44 preferably has a programmable time delay to automatically shut itself off a predetermined period of time after the engine 42 stops ru nning.

[Para 1 7] FIGURE 2 illustrates an electronically controlled, pneumatic adjustable fuel pressure regulator 1 0. Regulator 1 0 comprises a base unit 1 2 having a fuel port 1 4 therein. The fuel port 1 4 communicates with an interior chamber of the base unit 1 2. A diaphragm assembly 1 6 is disposed adjacent to the base unit 1 2 so as to cover and be in communication with the interior chamber. A resilient diaphragm spring 1 8 is disposed against the diaphragm assembly 1 6 so as to be capable of exerting a biasing force thereupon. A spring locator 20 is disposed at the opposite end of the spring 1 8. A ball bearing 22 is disposed against a face surface of the spring locator 20. Typically, a recess (not shown) is included in the face surface of the spring locator 20 to partially receive the ball bearing 22.

[Para 1 8] The diaphragm assembly 1 6 isolates regulated fuel in the base unit or fuel block 1 2 from mechanical components of the regulator 1 0. The isolation created by the diaphragm assembly 1 6 provides the ability for the regulator 1 0 to maintain a vacuum within the housing and allows the regulator to apply or reduce pressure by a vacuum demand from the manifold pressure signal.

[Para 1 9] The diaphragm spring 1 8 exerts pressure on the diaphragm assembly 1 6 so as to transfer the energy therethrough and activate a fuel pressure regulation circuit (FIG. 5) included within the base unit 1 2.

Simultaneously, the diaphragm spring 1 8 absorbs unwanted pressure spikes within the fuel supply system. The spring locator 20 acts as a centering device for the diaphragm spring as well as a seat for the mechanical adjustment screw. The check ball or ball bearing 22 acts as an intermediary device between the spring locator 20 and the adjustment screw 28. The same allows thrust and rotational forces during operation to be scrubbed off without gouging or wearing the abutting pieces.

[Para 20] A top cap 24 encloses the diaphragm assembly 1 6, spring 1 8, spring locator 20, and ball bearing 22 , and is secu red against a flange on the base unit 1 2. Screws 26 secure the top cap 24 to the flange of the base unit 1 2. An adjustment screw 28 extends through an opening (not shown) in the top cap and is sealingly held in place by a sealing ring 30, a washer 32, and a locking nut 34. The adjustment screw 28 is threaded along its length so as to have an adjustable depth into and out of the top cap 24 by action with the locking nut 34. A distal end 36 of the adjustment screw 28 is configured to engage the ball bearing 22 within the top cap 24. Movement of the adjustment screw 28 thus changes the relative position of the ball bearing 22 and the spring locator 20 so as to adjust the amount of compression on the spring 1 8. As the spring locator 20 is moved, the biasing force exerted by the spring 1 8 on the diaphragm assembly 1 6 either increases or decreases depending upon the direction of movement of the adjustment screw 28.

[Para 21 ] An input port 38 extends through a side wall of the top cap 24. The input port 38 allows for the creation of a vacuum or the exertion of additional pressure on the diaphragm assembly 1 6 within the pressure regulator 1 0. The fuel port 1 4 may either be an inlet port or an outlet port. A second port (not shown) acts as the opposite outlet or inlet for the fuel port 1 4. The diaphragm assembly 1 6 is configured to open or close a passage through the base unit 1 2 , which passage connects the fuel port 1 4 to another port.

[Para 22] The housing cap 24 encloses the mechanical preset fuel pressure circuit as well as the vacuum port nipple 38. The nipple 38 is to allow manifold pressure to be inducted into the housing cap 24 of the regu lator 1 0 so as to activate the primary fuel pressure circuit. The adjustment screw 28 is to set the base operating (non boost) fuel pressure within the regulator 1 0. Retention of the adjustment screw 28 is achieved by the sealing ring 30, washer 32 , and locking nut 34. The adjustment screw 28 passes through the housing cap 24 in a threaded manner so as to be rotatably advanced and retracted from the regu lator 1 0, thus controlling the pressure exerted on the diaphragm assembly 1 6 by the diaphragm spring 1 8.

[Para 23] FIGURE 3 illustrates a preferred embodiment of an electronically controlled mechanical fuel pressure regulator 40 according to the present invention. As with the prior art regulator 1 0, the inventive regulator 40 includes a base unit 1 2 having a fuel port 1 4, a diaphragm assembly 1 6 and a spring 1 8. It is at this point that the inventive regulator 40 is distinguished from the pneumatic regulator 1 0. The spring locator 20 is replaced by an internally threaded spring locator 52. The spring locator 52 engages the spring 1 8 as described above. This spring locator 52 includes a central bore 54 with internal threads 56. A retention spring 58 abuts against a face of the spring locator 52 opposite the spring 1 8. A coupler 60 replaces the top cap 24 and engages the flange of the base unit 1 2 in a manner similar to that described above.

[Para 24] A stepper motor 62 (or similarly configured motor) having a threaded output shaft 64 is attached to the coupler 60. The output shaft 64 extends through the coupler 60 in a sealed manner and through the retention spring 58 such that it engages the central bore 54 in the spring locator 52. External threads 66 on the output shaft 64 engage the internal threads 56 on the central bore 54 of the spring locator 52. Once so engaged, movement of the motor 62 to rotate the output shaft 64 will cause the spring locator 52 to exert a greater or lesser force on the spring 1 8 within the inventive regulator 40. Wiring 68 connects the stepper motor 62 to the microcontroller 44 or other control element in the system. A T-line fitted pressure transducer 70 may be affixed to the fuel port 1 4.

[Para 25] The stepper motor 62 is preferably electronically controlled by the microcontroller 44. The output shaft 64 acts as a male drive portion of a linear drive mechanism. The coupler 60 is an intermediate device that adapts the stepper motor 62 to the base unit 1 2. In addition, it houses the female portion of a linear drive mechanism, which includes the retention spring 58, spring locator 52 , diaphragm spring 1 8, and diaphragm assembly 1 6. The retention spring 58 applies pressure to the spring locator 52 to prevent the same from separating from the diaphragm spring 1 8 when the stepper motor 62 draws back the linear drive mechanism in order to reduce fuel pressure. The spring locator 52 acts as a centering device for the diaphragm spring 1 8, as well as the female portion of the linear drive mechanism.

[Para 26] As with the earlier embodiment, the diaphragm spring 1 8 exerts pressure on the fuel isolating diaphragm assembly 1 6. The diaphragm

assembly 1 6 transfers the pressure from the diaphragm spring 1 8 so as to activate the fuel pressure regulation circuit (FIG. 5) housed within the base unit 1 2. Simultaneously, the diaphragm spring 1 8 absorbs u nwanted pressure spikes in the fuel supply system. The diaphragm assembly 1 6 isolates the regu lated fuel in the base unit 1 2 from the mechanical linear drive mechanism that applies or removes pressure via the stepper motor 62. [Para 27] The base unit 1 2 is a fuel block that houses a diaphragm fuel pressure regulation circuit (FIG. 5) that is controlled by a vacuum created by the diaphragm assembly 1 6. The pressure transducer 70 "reads and returns" fuel pressure readings to the microcontroller 44. The microcontroller 44 analyzes these pressure readings to determine deviation from a "desired" fuel pressure and subsequent air to fuel ratio calculations. The microcontroller 44 translates the pressure readings from the transducer 70 so as to activate the stepper motor 62 to advance or retract the linear drive mechanism so as to obtain the desired fuel pressure readings and air to fuel ratio.

[Para 28] FIGURE 4 illustrates an alternate dual stage regulator 72. This dual stage regulator 72 combines the functionality of the pneumatic regulator 1 0 in a primary stage 74 and the mechanical regulator 40 in a secondary stage 76. The two stages 74, 76 are connected by a dual base unit 78 having a fuel port 80. The dual base unit 78 has the stages 74, 76 oppositely disposed such that the conventional regulator 1 0 and electronically controlled regulator 40 are disposed linearly. The stages may be configured in alternate orientations.

[Para 29] The primary and secondary stages 74, 76 are configured and operate as described above except with respect to the dual base unit 78. In the two stage unit 72, the secondary stage 76 implements the stepper motor 62 to apply and reduce pressure to the diaphragm spring 1 8 and the spring locator 20 in direct relation to intake manifold pressure so as to properly scale the calculated amount of fuel pressure required to obtain specific or desired air to fuel ratios when under positive manifold pressure (boost) conditions. [Para 30] FIGURE 5 illustrates a version of a single stage base unit 1 2 having fuel inlet port 1 4a and fuel outlet port 1 4b. The diaphragm assembly 1 6 sits flush against a surface of the base unit 1 2. A valve seat 1 6a extends into an interior chamber 1 2a of the base unit 1 2 and is configured to engage a valve port 1 6b that connects the inlet 1 4a with the outlet 1 4b. Depending upon the pressure exerted on the diaphragm assembly 1 6, the valve seat 1 6a may either seal off the valve port 1 6b or allow varying levels of fluid communication through the valve port 1 6b.

[Para 31 ] FIGURE 6 illustrates the interior of the dual base unit 78. The dual base unit 78 again has a fuel inlet 80a and a fuel outlet 80b. The respective diaphragm assemblies 1 6 abut against opposite surfaces of the dual base unit 78 so as to enclose interior chambers 78a. Each diaphragm assembly 1 6 again has a valve seat 1 6a and a valve port 1 6b. Depending upon the configuration of the respective regulators 1 0, 40, the valve seat 1 6a may either block valve port 1 6b or permit fluid communication therethrough. A fluid passageway 82 connects the interior chambers 78a, 78b through one of the valve ports 1 6b. In this way, the amount of fuel pressure permitted to pass through the dual base unit 78 can be adjusted by both the pneumatic regulator 1 0 and the mechanical regu lator 40.

[Para 32] Although several embodiments have been described in detail for purposes of illustration, various modifications may be made without departing from the scope and spirit of the invention. Accordingly, the invention is not to be limited, except as by the appended claims.