Abstract:
An engine control system comprises an engine speed monitoring module and a pump control module. The engine speed monitoring module compares an engine speed and a predetermined threshold. The pump control module deactivates a pressure pump based on said comparison.

Description:
FIELD 
     The present disclosure relates to high pressure pump control. 
     BACKGROUND 
     The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. 
     Referring now to  FIG. 1 , a functional block diagram of an engine system  100  is shown. Air is drawn into an engine  102  through an intake manifold  104 . A throttle valve  106  is actuated by an electronic throttle control (ETC) motor  108  to vary the volume of air drawn into the engine  102 . The air mixes with fuel from one or more fuel injectors  110  to form an air-fuel mixture. The air-fuel mixture is combusted within one or more cylinders  112  of the engine  102 . Resulting exhaust gas is expelled from the cylinders to an exhaust system  113 . 
     Fuel is supplied to the engine  102  by a fuel system. For example only, the fuel system may include the fuel injectors  110 , a fuel tank  114 , a low pressure pump  115 , a high pressure pump  116 , and a fuel rail  118 . Fuel is stored within the fuel tank  114 . The low pressure pump  115  draws fuel from the fuel tank  114  and provides fuel to the high pressure pump  116 . The high pressure pump  116  provides pressurized fuel to the fuel injectors  110  via the fuel rail  118 . 
     An engine control module (ECM)  120  receives a rail pressure signal from a rail pressure sensor  122 . The rail pressure signal indicates the pressure of the fuel within the fuel rail  118 . The ECM  120  controls the amount and the timing of the fuel injected by the fuel injectors  110 . The rail pressure decreases each time fuel is injected by one or more of the fuel injectors  110 . The ECM  120  maintains the rail pressure via the high pressure pump  116 . 
     The speed of the engine  102  is measured by a revolutions per minute (RPM) sensor  124 . The RPM sensor  124  provides the ECM  120  with the measured RPM. 
     SUMMARY 
     An engine control system comprises an engine speed monitoring module and a pump control module. The engine speed monitoring module compares an engine speed and a predetermined threshold. The pump control module deactivates a pressure pump based on the comparison. In further features, the engine speed monitoring module determines whether the engine speed is less than or equal to the predetermined threshold, and the pressure pump is deactivated based on the determination. In other features, the engine control system further comprises a fuel injector control module that adjusts a timing of actuation of a fuel injector based on the comparison. 
     In other features, the engine control system further comprises a fuel injector control module that adjusts a length of time of actuating a fuel injector based on the comparison. In still other features, the pump control module deactivates the pressure pump by adjusting a valve. In still other features, the engine speed monitoring module compares the engine speed to a second predetermined threshold, and the pump control module suspends deactivating the pressure pump when the engine speed is greater than or equal to the second predetermined threshold. 
     In other features, the engine speed monitoring module additionally compares an engine speed idle time and a predetermined period of time, and the pump control module deactivates the pressure pump based on the additional comparison. In other features, the engine speed monitoring module determines whether the engine speed idle time is greater than or equal to the predetermined period of time, and the pressure pump is deactivated based on the determination. 
     An engine control method comprises comparing an engine speed and a predetermined threshold, and deactivating a pressure pump based on the comparison. In further features, the engine control method further comprises determining whether the engine speed is less than or equal to the predetermined threshold, and deactivating the pressure pump based on the determination. In further features, the engine control method further comprises adjusting a timing of actuation of a fuel injector based on the comparison. 
     In other features, the engine control method further comprises adjusting a length of time of actuating a fuel injector based on the comparison. In other features, the engine control method further comprises deactivating the pressure pump by adjusting a valve In other features, the engine control method further comprises comparing the engine speed to a second predetermined threshold, and suspending deactivation of the pressure pump when the engine speed is greater than or equal to the second predetermined threshold. 
     In other features, the engine control method further comprises additionally comparing an engine speed idle time and a predetermined period of time, and deactivating the pressure pump based on the additional comparison. In other features, the engine control method further comprises determining whether the engine speed idle time is greater than or equal to the predetermined period of time, and deactivating the pressure pump based on the determination. 
     Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a functional block diagram of an engine system; 
         FIG. 2  is a functional block diagram of an exemplary engine system according to the principles of the present disclosure; 
         FIG. 3  is an exemplary implementation of the engine control module  208  of  FIG. 2  according to the principles of the present disclosure; and 
         FIG. 4  is a flowchart that depicts exemplary steps performed in deactivating the high pressure pump  202  of  FIG. 2  according to the principles of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A or B or C), using a non-exclusive logical or. It should be understood that steps within a method may be executed in different order without altering the principles of the present disclosure. 
     As used herein, the term module refers to an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. 
     A high pressure pump supplies pressurized fuel to a fuel rail. Fuel injectors are connected to the fuel rail and inject the pressurized fuel into a cylinder. The pressure within the fuel rail decreases as the fuel injectors inject more fuel. The rail pressure is monitored to determine whether the high pressure pump may supply more pressurized fuel. 
     The high pressure pump of the present disclosure is deactivated based on speed of an engine. When the high pressure pump is deactivated, the pressure within the fuel rail is not maintained. Fuel is supplied to the fuel rail by a low pressure pump and the pressure within the fuel rail decreases. The amount and timing of the fuel injected by the fuel injectors are modified to accommodate for the change in pressure. 
     Referring now to  FIG. 2 , a functional block diagram of an engine system  200  according to the principles of the present disclosure is shown. A high pressure pump  202  provides pressurized fuel to fuel injectors  204  via the fuel rail  118 . The high pressure pump  202  is controlled by a pump control module  206  that may be located within an ECM  208 . 
     The pump control module  206  receives a rail pressure signal from a rail pressure sensor  210 . The rail pressure signal indicates the pressure of the fuel within the fuel rail  118 . A fuel injector control module  212  controls the amount and the timing of the fuel injected by the fuel injectors  204 . The rail pressure decreases each time fuel is injected by one or more of the fuel injectors  204 . The pump control module  206  maintains the rail pressure via the high pressure pump  202 . The pressure of the fuel exiting the high pressure pump  202  may be greater than the pressure of the fuel exiting the low pressure pump  115 . For example only, the pressure of the fuel exiting the high pressure pump  202  may be between 2-26 Mpa, while the pressure of the fuel exiting the low pressure pump  115  may be between 0.3-0.6 Mpa. 
     The high pressure pump  202  includes a valve (not shown) that controls the pressure of fuel exiting the high pressure pump  202 . When the valve is fully open, the pressure of the fuel exiting the high pressure pump  202  is the same as the pressure of the fuel entering the high pressure pump  202 . By adjusting the valve to a position that is less than fully open, the pressure of the fuel exiting the high pressure pump  202  increases. The pump control module  206  may deactivate the high pressure pump  202 . For example only, the high pressure pump  202  may be deactivated by adjusting the valve to the fully open position. 
     When the high pressure pump  202  is deactivated, the fuel injector control module  212  adjusts the amount and the timing of the fuel injected by the fuel injectors  204 . For example, the pump control module  206  may generate a deactivation signal when the high pressure pump  202  is deactivated. The fuel injector control module  212  may adjust the amount and the timing of the fuel injected by the fuel injectors based on the deactivation signal. 
     The speed of the engine  102  is measured by a revolutions per minute (RPM) sensor  214 . The RPM sensor  214  provides the ECM  208  with the measured RPM. For example, the RPM sensor  214  may generate a RPM signal. The pump control module  206  receives the RPM signal from the RPM sensor  214 . Based on the RPM signal, the pump control module  206  may deactivate the high pressure pump  202 . For example only, the high pressure pump  202  may be deactivated when the RPM signal indicates that the RPM is less than or equal to a predetermined threshold. For example, if the high pressure pump  202  is deactivated, then the pump control module  206  generates a deactivation signal. 
     The fuel injector control module  212  modifies the timing and amount of fuel injected by the fuel injectors  204  when the deactivation signal is generated. The pump control module  206  resumes controlling the high pressure pump  202  and suspends generating the deactivation signal when the RPM is greater than the predetermined threshold. 
     Referring now to  FIG. 3 , an exemplary implementation of the engine control module of  FIG. 2  according to the principles of the present disclosure is shown. The pump control module  206  includes a pump actuation module  300  and an engine speed monitoring module  302 . The pump actuation module  300  controls actuation of the high pressure pump  202  based on rail pressure. The engine speed monitoring module  302  monitors the RPM signal. 
     The engine speed monitoring module  302  determines whether the RPM signal indicates that the RPM is less than or equal to a predetermined threshold. If the RPM is less than or equal to the predetermined threshold, then the engine speed monitoring module  302  generates a deactivation signal. In various implementations, the engine speed monitoring module  302  may generate the deactivation signal when the RPM is idle for at least a predetermined amount of time. 
     The engine speed monitoring module  302  may generate the deactivation signal until the RPM is greater than a second predetermined threshold. In various implementations, the second predetermined threshold may be equal to the predetermined threshold. The pump actuation module  300  and a fuel injector timing module  304  receive the deactivation signal. 
     The pump actuation module  300  suspends actuation of the high pressure pump  202  when the deactivation signal is generated. The pump actuation module  300  may suspend actuation of the high pressure pump  202  based on the deactivation signal. When actuation of the high pressure pump  202  is suspended, the pressure within the fuel rail  118  decreases. 
     The fuel injector timing module  304  may be located within the fuel injector control module  212 . The fuel injector timing module  304  controls the amount and the timing of the fuel injected by the fuel injectors  204 . For example only, the fuel injector timing module  304  may generate a fuel signal to control the opening of the fuel injectors  204 . By changing the timing of generating the fuel signal and the pulse width of the fuel signal, then the amount and timing of fuel injection changes. When the deactivation signal is generated, the fuel injector timing module  304  modifies the amount and the timing of the fuel injected by the fuel injectors  204 . 
     The fuel injector timing module  304  may continue modifying the generation of the fuel signal until the engine speed monitoring module  302  suspends generating the deactivation signal. When the deactivation signal is suspended, then the fuel injector timing module  304  may resume controlling the fuel injectors  204  as before the modifications to the fuel signal. 
     Referring now to  FIG. 4 , a flowchart that depicts exemplary steps performed in deactivating the high pressure pump  202  of  FIG. 3  according to the principles of the present disclosure. Control begins in step  400  where an engine is started. In step  402 , control activates a high pressure pump. In step  403 , control activates a fuel injector. In step  404 , control monitors engine speed. 
     In step  406 , control determines whether the engine speed is less than a predetermined threshold. If control determines that the engine speed is less than the predetermined threshold, then control transfers to step  408 ; otherwise, control transfers to step  410 . In step  408 , control deactivates the high pressure pump. In step  412 , control changes fuel injector timing. In step  414 , control changes fuel injector pulse width. 
     In step  410 , control monitors fuel rail pressure. In step  416 , control determines whether the fuel rail pressure is less than a predetermined threshold. If control determines that the fuel rail pressure is less than the predetermined threshold, then control transfers to step  418 ; otherwise, control returns to step  410 . 
     In step  418 , control actuates the high pressure pump. In step  420 , control determines whether the engine is off. If control determines that the engine is off, then control ends; otherwise, control returns to step  404 . 
     Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification, and the following claims.