ROTARY PUMP CONTROL RESPONSIVE TO CAM REACTION FORCES

Abstract: A control system for a rotary fuel injection pump (56) which has a timer piston (62), controlled by an timer motor (64), for adjusting the injection timing of the pump. The timer piston includes a housing containing a volume of hydraulic fluid which subjected to a pressure pulse having a peak pressure during each pumping event. A pressure transducer (70) mounted to the timer piston housing is responsive to the pressure of the hydraulic fluid and provides a pressure signal output indicative of the pressure of the hydraulic fluid. An engine controller (82) has a signal input portion in electrical communication with a top dead center detector (76), the pressure transducer (70), an engine control portion in electrical communication with the signal input portion, and the timer control motor (64). The signal input portion of the engine controller includes a cam position detection section, a pump speed detection section, and a delivered fuel detection section.

Description: ROTARY PUMP CONTROL RESPONSIVE TO CAM REACTION FORCES Background of the Invention The present invention relates generally to fuel injection systems of the type having a fuel injection pump for delivering high pressure liquid fuel pulses to the fuel injection nozzles of an internal combustion engine for injection of discrete charges of fuel into the engine cylinders. More particularly, the present invention relates to a new and improved fuel injection timing method and system for determining and regulating the timing of the fuel charge injection. Precise timing of the fuel charge injection into an engine cylinder (usually measured in relation to the top dead center (TDC) position of the cylinder operating piston) is a critical factor in maximizing the fuel efficiency of the engine and in minimizing the engine noise level and the pollutant discharge in the engine exhaust. Also, precise regulation of fuel charge injection timing is necessitated by increasing environmental considerations and regulatory mandates. Improved injection timing can be achieved by employing a more precise means for controlling the fuel injection timing and by employing more engine operation parameters in determining the optimum timing. In fuel injection pump timing systems having a high degree of precision, the means provided for advancing and retarding the fuel injection timing may be responsive to a control loop which periodically receives an update of the actual fuel injection timing for determining and applying the timing adjustment. Fuel charge injection normally occurs when the piston is at or near TDC. The desired time of fuel charge injection varies with the engine design and ranges from slightly prior to TDC to slightly after TDC. Quantification of fuel injection timing is commonly determined and expressed in terms of degrees of crankshaft rotation relative to TDC. In the normal course of engine operation, various engine operation data or parameters such as engine speed, load, temperature, and altitude or intake manifold pressure may vary sufficiently to require timing adjustments to maintain optimum fuel injection timing. For example, as the engine speed increases, the fuel injection timing should normally occur earlier relative to TDC. That is because the time required for fuel combustion (in terms of crankshaft degrees) increases with engine speed and therefore should be considered in determining the optimum fuel injection timing. Accordingly, the usual fuel injection pump normally employs a mechanism for adjusting the fuel injection timing with engine speed. Another change in the engine operation which requires a timing adjustment is the change in the engine load or quantity of the injected fuel charge. For example, advancing the fuel injection timing for rapid engine acceleration is generally advantageous. Also, a timing adjustment may be made to compensate for engine temperature. Thus, it is generally advantageous to advance the fuel injection timing in cold engine operation at relatively low speed. In fuel injection pumps of the type wherein the contour of a cam activates the fuel pressurizing plungers of a charge pump, the fuel injection timing may be controlled by an hydraulically operated timing control piston connected to advance or retard the pump timing. Prior art references disclose methods and systems for measuring the fuel injection timing by either sensing the movement of the fuel injection nozzle valve, sensing an increase in the fuel pressure at the fuel injection nozzle, or by sensing the expansion of the fuel injection line. The deficiencies of the prior art are particularly manifest either in restricting the fuel injection detection to only a single engine cylinder rather than all cylinders, which ultimately degrades the timing adjustment response time, or in requiring a separate detection device for each engine cylinder, thereby making the system expensive and complex. The prior art systems have additional problems in terms of providing detection means which accurately and reliably senses the fuel injection event over the normally wide range of engine operating characteristics and in the adverse fuel injection nozzle environment. The devices which are integrally built into the injection nozzle structure are impractical and expensive. Summary of the Invention Briefly stated, the invention in a preferred form is a control system for a rotary fuel injection pump which has opposed plungers which pump a flow of fuel to a diesel engine. A cam ring engaged with the plungers sequentially actuates pumping events. An timer piston may be used to adjust the injection timing by rotating the cam ring with respect to a fixed point. An timer control motor provides a means for actuating the timer piston. The timer piston includes a housing containing a volume of hydraulic fluid which subjected to a pressure pulse during each pumping event Each pressure pulse has a peak pressure. A top dead center detector detects when the crankshaft of the diesel engine is at top dead center and provides a TDC reference signal output. A pressure transducer mounted to the timer piston housing is responsive to the pressure of the hydraulic fluid and provides a pressure signal output indicative of the pressure of the hydraulic fluid. An engine controller has a signal input portion in electrical communication with the top dead center detector and the pressure transducer and an engine control portion in electrical communication with the signal input portion and the timer control motor. The signal input portion of the engine controller includes a cam position detection section providing a cam position signal, a pump speed detection section providing a pump speed signal, and a delivered fuel detection section providing a quantity of delivered fuel signal. The cam position detection section includes an input conditioning module in electrical communication with the top dead center detector and a signal conditioning module in electrical communication with the input conditioning module, the pump speed detection section, and the engine control portion. The input conditioning module initiates a cam position signal upon receipt of the TDC reference signal output. The signal conditioning module terminates the cam position signal upon receipt of the pump speed signal from the pump speed detection section. The pump speed detection section includes a percent of peak detector in electrical communication with the pressure transducer and a signal conditioning module in communication with the percent of peak detector and the engine control portion. The percent of peak detector initiates a logic level output when the pressure signal output reaches a predetermined percentage of the peak pressure. The signal conditioning module receives the logic level output and provides a pulse signal indicative of the speed of the pump. The signal conditioning module is further in electrical communication with the cam position detection section. The percent of peak detector may have an output timing signal defining the delivered fuel detection system. Alternatively, the percent of peak detector may be in electrical communication with the delivered fuel detection system. In one embodiment, the delivered fuel detection section includes an integrator module in electrical communication with the pressure transducer, a timing control module in electrical communication with the pump speed detection section, and a sample and hold module in electrical communication with the integrator module, the timing control module, and the engine control portion. The integrator module integrates the pressure signal output over the period of the pressure pulse and provides an output having a value corresponding to the integral. The timing control module provides a timing signal to the sample and hold module upon receipt of the pump speed signal from the pump speed detection section. The sample and hold module stores the output of the integrator module and transmits the output of the integrator module to the engine control portion upon receipt of the timing signal. In a second embodiment, the delivered fuel detection section includes a peak detector in electrical communication with the pressure transducer, a timing control module in electrical communication with the pump speed detection section, and a sample and hold module in electrical communication with the peak detector, the timing control module, and the engine control portion. The peak detector senses the value of the peak pressure and provides an output having a value corresponding to the peak pressure. The timing control module provides a timing signal to the sample and hold module upon receipt of the pump speed signal from the pump speed detection section The sample and hold module stores the value of the peak pressure and transmits this value to the engine control portion upon receipt of the timing signal. In a third embodiment, the either the engine control portion or a module in the pump speed detection section measures the time between logic level outputs of the percent of peak detector to determine the delivered fuel. It is an object of the invention to provide a new and improved control system for rotary fuel injection pumps. It is also an object of the invention to provide a rotary fuel injection pump control system that obtains three of the parameters from a single pressure transducer which senses the hydraulic fluid pressure in the timer piston of the pump. Other objects and advantages of the invention will become apparent from the drawings and specification. Brief Description of the Drawings The present invention may be better understood and its numerous objects and advantages will become apparent to those skilled in the art by reference to the accompanying drawings in which: Figure 1 is a simplified, partial transverse section view, partly in section of a fuel injection pump of a type with which the engine control system of the invention may be employed; Figure 2 is a schematic view of the pressure transducer, top dead center sensor, engine control portion of the engine controller, and a first embodiment of the signal input portion of the engine controller; Figure 3 is a schematic view of the pressure transducer, top dead center sensor, engine control portion of the engine controller, and a second embodiment of the signal input portion of the engine controller; Figure 4 is a schematic view of the pressure transducer, top dead center sensor, engine control portion of the engine controller, and a third embodiment of the signal input portion of the engine controller; and Figure 5 is a side view, partly broken away and partly in section of the fuel injection pump of Figure 1 . Detailed Description of the Preferred Embodiment In the drawings, the same numerals are used to identify the same or like functioning parts or components. An engine control system 10 responsive to cam reaction forces may be used to control a fuel injection pump 1 2 of the type shown in Figures 1 and 5. The pump 1 2 includes a housing and a distributor rotor 14 journaled within a fuel distributor sleeve 1 5 of a hydraulic distributor head 1 6 of the pump housing. A low pressure transfer pump 17 is provided at one end of the rotor 14. The transfer pump 17 has an inlet to which fuel is supplied from a supply tank (not shown). The outlet of the transfer pump is connected to a fuel inlet annulus 1 8 in the sleeve 1 5 via a passage and an annulus in the hydraulic distributor head 1 6 and via a fuel inlet metering valve. The rotor 14 has a pair of fuel inlet passages 1 9 and a fuel discharge passage 20. As the rotor 14 turns, the inlet passages 1 9 register sequentially with a plurality of radial ports 21 (only two of which are shown) uniformly spaced around the sleeve 1 5 in a plane of rotation of the inlet passages 1 9 to provide periodic communication by the fuel inlet annulus 1 8 with the inlet passages 1 9 for supplying fuel to the rotor 14. Similarly, the discharge passage 20 communicates sequentially with a plurality of fuel outlet passages 23 (only one of which is shown). The fuel outlet passages 23 are uniformly spaced around the sleeve 1 5 in the plane of rotation of the discharge passage 20 so that the rotor 14, as it rotates, sequentially delivers pressurized fuel pulses to a plurality of fuel connectors for delivery of the pressurized fuel pulses to the respective fuel injection nozzles of the associated engine (not shown) for injection of fuel charges into the engine cylinder. A delivery valve 25 is mounted within an axial passage in the rotor 14 to control the backflow of pressurized fuel from the discharge passage 20 after the fuel charge injection. The rotor 14 has an enlarged generally cylindrical portion with a diametral bore 24 receiving a pair of diametrically opposed pumping plungers 26. The space between the inner ends of the plungers 26 forms a high pressure pump chamber 22 connected to the inlet passages 1 9 and the discharge passage 20 by an axial passage 27 to alternately receive and discharge fuel as the rotor 14 turns. Surrounding the plungers 26 in their plane of revolution is a generally circular cam ring 52. The cam ring 52 is mounted in a bore 28 of the housing for limited angular movement. The angular position of the cam ring 52 is controlled by a timing or advance piston 62 which is mechanically connected to the cam ring 52 by a connector. The cam ring 52 has an inner annular cam surface with a plurality of pairs of diametrically opposed inwardly projecting cam lobes 54 for periodically and simultaneously actuating the plungers 26 inwardly. A roller assembly comprising a roller 48 and a roller shoe 46 is disposed between each plunger 26 and the cam ring 52 so that the rollers 48 follow the cam surface to translate the cam contour into reciprocable movement of the plungers 26. In operation, as the rotor 14 is driven by the associated engine (not shown) via the pump drive shaft 29, low pressure fuel from the transfer pump 1 7 is delivered through a port 21 to a rotor inlet passage 1 9 to the pump chamber 22, the opposed rollers 48 being angularly disposed with respect to the cam lobes 54 of the cam ring 52 to permit the plungers 26 to move radially outwardly in synchronism with the registry of an inlet passage 1 9 with each port 21 for fuel to enter the chamber 22. As the rotor 14 continues to rotate, the inlet passage 1 9 moves out of registry with the port 21 and the plungers 26 are actuated inwardly by a pair of opposed cam lobes 54 to produce a high pressure fuel pulse in the pump chamber 22. At the same time, the discharge passage 20 moves into registry with a delivery passage 23 connected to one of the engine cylinders (not shown) for delivery of a high pressure fuel pulse to the respective fuel injection nozzle for injection of a fuel charge into the engine cylinder. Continued rotation of the rotor repeats the process for sequential delivery of a charge of fuel to each engine cylinder in proper synchronism with the engine rotation. With reference to Figure 1 , the cam ring 52 is mounted so that it can be angularly adjusted to control the timing of the pumping strokes of the plungers 26. The pumping strokes can be adjusted to occur sooner (advanced) or later (retarded) as the drive shaft 29 rotates by a timing control system 56. The timing control system 56 includes the timing piston 62 which is mounted within a cylinder 30 in housing 68. The cylinder 30 extends tangentially to and in substantially the same plane as the cam ring 52. The control piston 62 has a radial bore receiving the connector 31 , and an upper rounded portion of the connector 31 interacts with the cam ring 52 for angularly shifting the cam ring 52 with the piston 62. The piston 62 has an axial bore receiving a servo valve or piston. The servo valve is biased outwardly by a light compression spring 32 at the inner end of the servo valve bore. A shiftable servo valve operating pin 33 extends axially through an opening in the cylinder end wall 34 into engagement with the outer end of the servo valve to establish the axial position of the servo valve. The inner end of the servo valve bore is connected via an axial bore through the servo valve to its opposite end to balance the fuel pressure on the opposite ends of the servo valve. The axial position of the pin 33 is controlled by a suitable bidirectional rotary stepping motor or actuator 64 mounted on the pump housing in axial alignment with the servo valve. The pin 33 is longitudinally positioned by the actuator 64 in response to a control signal (i.e. advance and retard stepping pulses). Fuel under a regulated pressure is supplied by the transfer pump 1 7 via a passage to a servo valve piston annulus. When the servo valve is shifted outwardly, to the right as viewed in Figure 1 , fuel is conducted to an advance or operating chamber 35 (at the left end of the cylinder as shown in Figure 1 ) via an inlet port of a passage in the control piston 62. At the same time, the servo valve covers an outlet port of an exhaust passage to prevent flow of fuel from the chamber 35 to the outer low pressure end of the bore. The timing piston 62 is thereby hydraulically actuated to the right as viewed in Figure 1 until the servo valve piston land covers the inlet port of passage to terminate the flow of fuel to the chamber 35. When the servo valve is shifted inwardly by the pin, to the left as seen in Figure 1 , fuel is exhausted from the operating chamber 35 via the outlet passage. The timing piston is thereby actuated to the left as viewed in Figure 1 by the spring 32 until an equilibrium position of the timing piston 62 is attained. Accordingly, the timing piston 62 is hydraulically positioned to match the axial position of the servo valve and therefore the axial position of the actuator pin 33. With further reference to Figure 1 , a pressure sensor or transducer 70 is mounted at the end of the piston operating bore for sensing hydraulic pressure spikes or pulses within the timing piston operating chamber 35. For each inward actuation or pumping stroke of the opposed plungers 26, a reaction force to the inward actuating force of the plungers 26 is transmitted via the plunger operating cam 52, connector pin 33 and the timing piston 62 to the hydraulic fluid 66 (fuel) in the timing piston operating chamber 35. Because of the relative incompressibility of fuel, the reaction force produces a sharp hydraulic pressure pulse or spike in the operating chamber 35. Each such pressure spike is detected by the sensor 70 and the sensor generates and transmits a corresponding sharp electrical signal 80 indicative of a fluid pressure spike occurrence. The pressure spike typically is significantly above the transfer fuel pressure within the operating chamber. It is desirable to electronically sense the speed and fuel delivery of a rotary distributor type fuel pump 1 2 for the purposes of injection timing and engine speed and torque control. For example, by measuring the time period between the top dead center (TDC) reference signal 74 provided by a known cylinder and a crankshaft mounted top dead center detector 76 to the speed pulse 96, cam position, and thus injection timing can be measured. In addition, the pressure pulse may be utilized in computing delivered fuel quantity. Delivered fuel quantity is a function of pump speed and engine load. As the quantity of fuel required by the engine increases, reaction forces on the cam are also increased. These forces increase the magnitude of the pressure pulses measured by the pressure transducer 70. It has been determined that three attributes of the pressure pulse, the pulse area, the pulse duration, and the peak pressure, are proportional to pump speed. With reference to Figures 2, 3 and 4, the signal input portion 78 of the engine controller 79 receives and processes the pressure signal 80 and the TDC reference signal 74 to provide suitable analog and digital signals for use by the engine control portion 82 of the engine controller 79. More specifically, the signal input portion 78 includes modules defining a cam position detection section 84, a pump speed detection section 86, and a delivered fuel detection section 88. With further reference to Figure 2, the pump speed detection section 86 includes a percent of peak detector 90 and a signal conditioning module 92. The percent of peak detector 90 includes a sample and hold module that stores the value of the peak pressure for the previous pumping event. Alternatively, the sample and hold module may store an average value of the last N number of pumping events. When the sensed value of the pressure of the current pumping event reaches a predetermined percentage of the value stored in the sample and hold module, for example 50%, the percent of peak detector 90 initiates a logic level output 94 indicating the beginning of each fuel pumping event. The minimum value of the predetermined percentage is above the level of noise which may be present in the pressure signal 80 to preclude inadvertent initiation of the logic level output 94. The use of a percentage of the peak pressure also eliminates uncertainties related to delays in detecting the occurrence of the peak pressure in the current pumping event. The signal conditioning module 92 receives the logic level output 94 from the percent of peak detector 90 and provides pulse signals 96 indicative of the speed of the pump 1 2 for use by the engine control portion 82 and the cam position detection section 84. The output of the pump speed detection section 86 is used for three purposes. First, the output is used in calculating the cam position feedback. The cam position feedback is calculated by measuring the period of time between the occurrence of a crankshaft mounted TDC reference signal 74, and the occurrence of the first fuel pumping event following the TDC reference. This feedback signal 98 may be used to control the hydraulic servo timer piston 62 and thereby control closed loop injection timing. The TDC reference signal 74 is received by an input conditioning module 100 which initiates a signal 102 when the TDC reference signal 74 indicates that the crankshaft is at top dead center. A signal conditioning module 104 receives the signal 102 from the input conditioning module 100 and terminates the signal 102 when it receives a signal 106 from the signal conditioning module 92 of the pump speed detection section 86. The length of the pulse 108, that is the time between initiation of the signal 102 in the input conditioning module 100 and termination of the signal 102 in the signal conditioning module 104 represents the time period defined above. Second, the output from signal conditioner 92 is used to provide an interrupt signal to the engine control portion 82 to notify it that a valid fuel measurement is available. Third, the output of the percent of peak detector 90 provides timing signal 109 to the timing control 1 10 of the delivered fuel detection section 88, as described below. The engine control portion 82 may also utilize the pump speed information contained in the pump speed signal 96. The area of the pressure pulse is proportional to the magnitude of the fuel delivered in each pumping event at a known RPM. An integrator module 1 1 2 integrates the pressure signal 80 from the pressure transducer 70 over the period of the pressure pulse and provides an output signal 1 14 which is proportional to the magnitude of the pulse over the entire period. The signal 1 14 is stored in the sample and hold module 1 1 6. When the sample and hold module 1 1 6 receives a signal 1 18 from the timing control 1 10 (as determined by the signal 109 from the percent peak detector 90), the pulse area signal 1 14 is transmitted to the engine control portion 82 which has been readied by the signal 96 from signal conditioner 92. In addition to causing the sample and hold module 1 1 6 to hold the delivered fuel signal 1 14 in a valid state until the engine control portion 82 can read it, signal 1 18 resets the output of the sample and hold module 1 16 to an initial state. Resetting the signal 1 14 after each injection is necessary in order to detect decreasing fuel quantity. With reference to Figure 3, The magnitude of the pressure pulse can also be used to determine fuel delivery. Peak pressure, at a known RPM, is proportional to the magnitude of the delivered fuel. A peak detector 1 20 and a sample and hold module 1 1 6 are used to monitor the pressure signal 80 and produce a stable output that a microprocessor can measure. The peak detector 1 20 measures the value of the pressure monitored by the transducer 70 and sends a signal 1 22 representing the peak value of each pumping event. The value of the peak pressure is stored in the sample and hold module 1 1 6 which operates in the same manner as described above for Figure 2 to send the peak pressure signal 1 22' to the engine control portion 82. With reference to Figure 4, the length or duration of a pumping event may be used to determine fuel delivery. As pump speed increases, the duration of each pumping event proportionally decreases. The duration of a pumping event may be determined by measuring the time between a threshold at the start and end of each pumping event or timer pressure pulse. As described above, the percent of peak detector 90 initiates a logic level output 94 when the sensed value of the pressure of the current pumping event reaches a predetermined percentage of the value of the pressure of the previous pumping event or average of the previous N number of pumping events. In other words the percent of peak detector provides a logic level output 94 when a pumping begins and ends. Measuring the time 1 24 between output signals 94, 94' from the percent of peak detector 90 provides a measurement of the duration of the pumping event. For diesel engine timing to be properly controlled, it is necessary to know at least three operating parameters in real time, engine speed, injected fuel quantity, and actual cam position. Desired cam position is then derived primarily as a function of these three parameters. This invention allows the electronic measurement of injected fuel quantity and current cam position using a single pressure transducer. While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.

Claims: What is claimed is: 1 . A control system for a rotary fuel injection pump having opposed plungers pumping a flow of fuel to an engine, a cam ring engaged with the plungers for sequentially actuating pumping events, a timer piston for adjusting the injection timing by rotating the cam ring with respect to a fixed point, and a timer control motor for actuating the timer piston, the timer piston including a housing containing a volume of hydraulic fluid subjected to a pressure pulse during each pumping event, each pressure pulse having a peak pressure, the engine having a crankshaft, the control system comprising: a top dead center detector for detecting when the crankshaft of the engine is at top dead center, the top dead center detector providing a TDC reference signal output; a pressure transducer responsive to the pressure of the hydraulic fluid and providing a pressure signal output indicative of the pressure of the hydraulic fluid; and an engine controller having a signal input portion in electrical communication with the top dead center detector and the pressure transducer and an engine control portion in electrical communication with the signal input portion and the timer control motor. 2. The control system of claim 1 wherein the signal input portion of the engine controller includes a cam position detection section providing a cam position signal, a pump speed detection section providing a pump speed signal, and a delivered fuel detection section providing a quantity of delivered fuel signal. 3. The control system of claim 2 wherein the cam position detection section includes an input conditioning module in electrical communication with the top dead center detector and a signal conditioning module in electrical communication with the input conditioning module, the pump speed detection section, and the engine control portion, the input conditioning module initiating a cam position signal upon receipt of the TDC reference signal output, the signal conditioning module terminating the cam position signal upon receipt of the pump speed signal from the pump speed detection section. 4. The control system of claim 2 wherein the pump speed detection section includes a percent of peak detector in electrical communication with the pressure transducer and a signal conditioning module in communication with the percent of peak detector and the engine control portion, the percent of peak detector initiating a logic level output when the pressure signal output reaches a predetermined percentage of the peak pressure, the signal conditioning module receiving the logic level output and providing a pulse signal indicative of the speed of the pump. 5. The control system of claim 4 wherein the signal conditioning module is further in electrical communication with the cam position detection section. 6. The control system of claim 4 wherein the percent of peak detector has an output timing signal defining the delivered fuel detection system. 7. The control system of claim 4 wherein the percent of peak detector is further in electrical communication with the delivered fuel detection system. 8. The control system of claim 2 wherein the delivered fuel detection section includes an integrator module in electrical communication with the pressure transducer, a timing control module in electrical communication with the pump speed detection section, and a sample and hold module in electrical communication with the integrator module, the timing control module, and the engine control portion, the integrator module integrating the pressure signal output over the period of the pressure pulse and providing an output having a value corresponding to the integral, the timing control module providing a timing signal to the sample and hold module upon receipt of the pump speed signal from the pump speed detection section, the sample and hold module storing the output of the integrator module and transmitting the output of the integrator module to the engine control portion upon receipt of the timing signal. 9. The control system of claim 2 wherein the delivered fuel detection section includes a peak detector in electrical communication with the pressure transducer, a timing control module in electrical communication with the pump speed detection section, and a sample and hold module in electrical communication with the peak detector, the timing control module, and the engine control portion, the peak detector sensing the value of the peak pressure and providing an output having a value corresponding to the peak pressure, the timing control module providing a timing signal to the sample and hold module upon receipt of the pump speed signal from the pump speed detection section, the sample and hold module storing the value of the peak pressure and transmitting the value of the peak pressure to the engine control portion upon receipt of the timing signal. 10. The control system of claim 2 wherein the pump speed detection section includes a percent of peak detector in electrical communication with the pressure transducer, the percent of peak detector initiating a logic level output when the pressure signal output reaches a predetermined percentage of the peak pressure, the engine control portion measuring the time between logic level outputs to determine the delivered fuel. 1 1 . A control system for a rotary fuel injection pump having opposed plungers pumping a flow of fuel to an engine, a cam ring engaged with the plungers for sequentially actuating pumping events, a timer piston for adjusting the injection timing by rotating the cam ring with respect to a fixed point, and a timer control motor for actuating the timer piston, the timer piston including a housing containing a volume of hydraulic fluid subjected to a pressure pulse during each pumping event, each pressure pulse having a peak pressure, the engine having a crankshaft, the control system comprising: top dead center detector means for providing a TDC reference signal when the crankshaft of the engine is at top dead center; pressure detector means responsive to the pressure of the hydraulic fluid for providing a pressure signal output indicative of the pressure of the hydraulic fluid; engine controller means responsive to the top dead center detector means and the pressure detector means for providing cam position, pump speed, and delivered fuel output signals for controlling the timer control motor. 1 2. The control system of claim 1 1 wherein the engine control means comprises a signal input portion having a cam position detection section providing a cam position signal, a pump speed detection section providing a pump speed signal, and a delivered fuel detection section providing a quantity of delivered fuel signal. 13. The control system of claim 1 2 wherein the cam position detection section includes a input conditioning means responsive to the top dead center detector means for initiating a cam position signal upon receipt of the TDC reference signal output and signal conditioning means responsive to the pump speed detection section for terminating the cam position signal upon receipt of the pump speed signal. 14. The control system of claim 1 2 wherein the pump speed detection section includes percent of peak detector means responsive to the pressure detector means for initiating a logic level output when the pressure signal output is a predetermined percentage of the peak pressure and signal conditioning means responsive to the percent of peak detector means for providing a pulse signal indicative of pump speed. 1 5. The control system of claim 1 2 wherein the delivered fuel detection section includes integrator means responsive to the pressure detector means for integrating the pressure signal output over the period of the pressure pulse and providing an output having a value corresponding to the integral, timing control means responsive to the pump speed detection section for providing a timing signal upon receipt of the pump speed signal, and a sample and hold means responsive to the integrator means and timing control means for storing and transmitting the output of the integrator means upon receipt of the timing signal. 1 6. The control system of claim 1 2 wherein the delivered fuel detection section includes peak detector means responsive to the pressure detector means for sensing the value of the peak pressure and providing an output corresponding to the value of the peak pressure, timing control means responsive to the pump speed detection section for providing a timing signal upon receipt of the pump speed signal, and a sample and hold means responsive to the peak detector means and timing control means for storing and transmitting the output of the peak detector means upon receipt of the timing signal. 1 7. The control system of claim 1 2 wherein the pump speed detection section includes percent of peak detector means responsive to the pressure detector means for initiating a logic level output when the pressure signal output is a predetermined percentage of the peak pressure and means for measuring the time between logic level outputs.

Inventors: BLAZE PHILIP J, NELSON ERIC A, BLAZE, PHILIP, J., NELSON, ERIC, A.
Applicants: BLAZE PHILIP J, NELSON ERIC A, STANADYNE AUTOMOTIVE CORP, BLAZE, PHILIP, J., NELSON, ERIC, A., STANADYNE AUTOMOTIVE CORP.
Application year: 1999
Main classification: E02F
IPC codes: F02D1, F02M41