Patent Publication Number: US-6217480-B1

Title: Engine control

Description:
FIELD OF THE INVENTION 
     The present invention relates to an engine control. More particularly, the present invention is an engine control in which one or more cylinders of the engine are disabled during one or more operating conditions. 
     BACKGROUND OF THE INVENTION 
     It is well known to use an electronic engine control to control various aspects of an internal combustion engine. As one example, engine controls are often used to control the ignition circuit which fires an ignition element corresponding to each cylinder of the engine. In such an arrangement, the engine control may be used to adjust the timing of the firing of the ignition element and thus advance or retard the ignition based on an operating condition of the engine. 
     Along these same lines, the engine control may be used to entirely prevent the firing of the ignition element of one or more cylinders or to so substantially adjust the timing of the firing to misfire one or more cylinders under certain operating conditions. This prevention of firing or substantial misfiring is generally referred to as cylinder disabling, since combustion does not occur in the cylinder at all or occurs at a time which is ineffective in powering the engine. 
     It has been proposed to use the cylinder disabling feature when the engine is idling. When the engine is idling, the firing of some but not all of the cylinders has the advantage that engine temperature is reduced since combustion is not occurring in one or more of the cylinders. When fuel is not supplied to the disabled cylinder(s), the fuel consumption rate of the engine is also advantageously decreased. 
     A significant disadvantage to such a cylinder disabling strategy is that the operator of the engine has no control over whether the control unit operates the engine in a disabling mode. In general, the control is arranged to operate the disabling mode anytime an indicator of engine idling is provided. In some instances, however, this indication may be provided when in fact the operator of the engine desires a high engine power output. 
     It is an object of the present invention to provide an engine control which employs a cylinder disabling mode at certain engine idle conditions, but which is arranged to prevent operation of the cylinder disabling mode during certain other conditions. 
     SUMMARY OF THE INVENTION 
     The present invention is an engine control for an engine. Preferably, the engine is of the internal combustion type and includes at least two cylinders or combustion chambers. 
     The engine control includes means for disabling at least one of the cylinders. In the preferred embodiment, the means for disabling is not activated until a predetermined condition is detected for a predetermined time. Preferably, the means for disabling is not activated unless an idle condition of the engine is detected for a predetermined time. 
     In still a further embodiment of the engine, the engine is operable in first and second states and the means for disabling may also be activated even if the predetermined time has not passed if the state of the engine has not changed. Preferably, this first and second states comprise a drive state of the engine relative to a water propulsion device. 
     In an alternate embodiment, the engine is arranged to power a water propulsion device of an outboard motor propelling a watercraft and the means for disabling is not activated unless the speed of the watercraft is below a predetermined speed. 
     Advantageously, the engine control of the present invention is arranged to operate the engine in a cylinder disabling mode only upon the occurrence of certain conditions. Thus, the disabling mode is not activated when, for example, the engine is enters an idle mode only for a short period of time. 
     Further objects, features, and advantages of the present invention over the prior art will become apparent from the detailed description of the drawings which follows, when considered with the attached figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 schematically illustrates an engine powering an outboard motor and having a control in accordance with the present invention; 
     FIG. 2 is a cross-sectional view of a top portion of the motor and illustrated in FIG. 1 exposing a portion of the engine positioned in a cowling thereof; 
     FIG. 3 schematically illustrates a portion of the intake and cooling systems for the engine illustrated in FIG. 1; 
     FIG. 4 graphically illustrates the output of a first transmission shift sensor of the engine control; 
     FIG. 5 graphically illustrates the output of a second transmission shift sensor of the engine control; 
     FIG. 6 schematically illustrates a control strategy for the control of the present invention; and 
     FIG. 7 schematically illustrates another control strategy for the control of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
     FIGS. 1 and 2 illustrate an outboard motor  20  powered by an engine  22  controlled with an engine control in accordance with the present invention. The control of the present invention is described with an engine  22  utilized to power an outboard motor  20  since this is an application with which an engine controlled with the control has particular utility. As may be appreciated by one skilled in the art, the engine control may be used to control an engine used in a variety of other applications. 
     In general, and as described in more detail below, the engine control of the present invention is arranged to selectively disable one or more cylinders of the engine dependent on one or more operating conditions. 
     Referring to FIGS. 1 and 2, the outboard motor  20  has a powerhead which comprises the engine  22  positioned in a cowling  24 . A lower unit  26  extends below the powerhead. The outboard motor  20  is connected to the hull  28  of a watercraft  30 , preferably at a transom portion of the watercraft  30 . The motor  20  is connected to the watercraft  30  by a clamping bracket  32 . Preferably, the motor  20  is connected to the clamping bracket  32  in a manner which permits side-to-side movement about a vertically extending axis for permitting steering of the watercraft  30  with the motor, and in a manner which permits movement up and down about a horizontally extending axis for permitting trimming of the motor  30 . These mountings are well known to those skilled in the art. 
     The engine  22  includes a cylinder block  34  having a cylinder head  36  connected thereto and cooperating therewith to define four cylinders  38 , each cylinder including a combustion chamber portion  39 . As is known to those skilled in the art, the engine  22  may have a greater or lesser number of cylinders  38  than four. 
     In the present embodiment, a piston  40  is movably mounted in each cylinder  38 . Each piston  40  is connected to a crankshaft  42  which is journalled for rotation with respect to the remainder of the engine  22  via a connecting rod  44 . The crankshaft  42  is preferably positioned in a crankcase chamber defined by the block  34  opposite the cylinder head  36  and enclosed with a crankcase cover  43 . 
     The crankshaft  42  is generally vertically extending, and likewise the cylinders  38  are preferably arranged in in-line vertical fashion. As known to those skilled in the art, the engine  22  may be arranged in other orientations, such as a “V” arrangement. In addition, the engine  22  may be of the rotary type. 
     As illustrated in FIG. 1, the crankshaft  42  is preferably arranged to drive a drive shaft  46  which extends through the lower unit  26  of the motor  20  to drive a means for propelling water. In the embodiment illustrated, the drive shaft  46  extends to a forward-neutral-reverse transmission  50 . This transmission  50  may be of a variety of types. As illustrated, the transmission  50  includes a bevel gear  52  mounted on the end of the drive shaft  46  for selective engagement with forward and reverse bevel gears  54 , 56  mounted on a propeller drive shaft  58 . The propeller drive shaft  58  extends to the means for propelling water, which in the present invention is illustrated as a propeller  60  having at least one blade  62 . 
     A shift mechanism  61  is provided for permitting the operator of the watercraft  30  to shift the transmission  50  between forward, neutral and reverse positions. As illustrated, the mechanism  61  includes a shift lever  63  moveable between F, N and R positions corresponding to forward, neutral and reverse transmission positions, respectively. The shift lever  63  is connected via a shift cable  65  to a shift rod  67  extending through the lower unit  26  of the motor  20  to the transmission  50 . As illustrated, the shift rod  67  is arranged to rotate and move the forward and reverse bevel gears  54 , 56  into selective engagement with the bevel gear  52  on the drive shaft (or into a position in which neither gear  54 , 56  engages the bevel gear  52  in a neutral position). 
     Air is provided to each cylinder  38  for use in a fuel combustion process. Referring to FIG. 2, air is drawn through a vent  64  in the cowling  24  of the motor  20 . The air entering the cowling  24  is then drawn into an inlet  68  into an intake system  66 . In the embodiment illustrated, the air is routed through a passage extending across the top of the engine  22  to a surge tank  70 . 
     Air is drawn from the surge tank  70  through a throttle body  72  and delivered into a manifold  74  which includes individual runners  76  corresponding to each cylinder  38 . The rate of air flow to the cylinders  38  of the engine  22  is preferably governed by a throttle plate  80  movably mounted in a passage through the throttle body  72 . This plate  80  is preferably remotely movable by an operator of the watercraft  30  from a position in which the plate  80  generally obstructs the passage and other positions in which the throttle plate  80  generally does not obstruct the passage. 
     Each runner  76  has a passage  82  therethrough leading to an intake port of a cylinder  38 . As illustrated in FIG. 1, means are provided for controlling the timing of the flow of air into each cylinder  38 . Preferably, this means comprises an intake valve  84  having one end positioned in the intake port. The valve  84  is preferably actuated between one position in which is obstructs or closes the-port and a second position in which the port is opened by an intake camshaft  86 . 
     Preferably, the intake camshaft  86  is arranged to actuate the intake valve  84  corresponding to all of the cylinders  38 . Means are provided for driving the camshaft  86 , as well known in the art. For example, this means may comprises a chain or belt extending from the crankshaft  42  to the camshaft  86  whereby the crankshaft  42  drives the camshaft  86 . 
     Fuel is also supplied to the cylinder  38  for combustion therein. Preferably, the fuel is supplied through a suitable charge former, such as a fuel injector  88 . As illustrated, a fuel injector  88  is provided corresponding to each runner  76  and delivers fuel into the air passing through the passage  82  corresponding thereto. 
     Fuel is supplied to each fuel injector  88  by a fuel supply system which preferably includes means for delivering fuel from a supply to the injector  88  at high pressure. The fuel is preferably supplied to the injectors  88  through a fuel rail  90  extending generally vertically along the cylinder head  38  of the engine  22 . 
     Products of the combustion process are routed from each cylinder  38  through an exhaust port leading to an exhaust passage  92 . The exhaust passage  92  leading from each cylinder  38  preferably extends to a common exhaust passage  94  leading to a point external to the motor  20 . 
     Means are provided for controlling the flow of exhaust from each cylinder  38  to its respective exhaust passage  92 . Preferably, this means comprises an exhaust valve  96  having one end position in the exhaust port. The exhaust valve  96  is moveable between a first position in which it obstructs or closes the exhaust port and prevents the flow of exhaust therethrough, and a second open position in which exhaust is permitted to flow from the cylinder  38  to the exhaust passage  92 . Preferably, the valve  96  is actuated by an exhaust camshaft  98 . The camshaft  98  is preferably driven in like manner to the intake camshaft  86 . 
     The details of the remainder of the exhaust system are not provided herein as they form no part of the present invention, and are well known to those skilled in the art. 
     The engine  22  preferably includes a cooling system. As illustrated in FIG. 3, cooling water is preferably supplied by a pump  91  to a cooling jacket  93  surrounding at least a portion of each cylinder  38 . The coolant may be water in which the motor  20  is operating drawn through an inlet. 
     The coolant flows through the jacket  93  and, selectively, to a discharge. Preferably, a thermostat  95  controls the flow of coolant from the jacket  93  to the discharge. The thermostat  95  is arranged to stop the flow of coolant to allow the engine  22  to warm up, and to permit coolant to flow freely through the jacket  93  when the engine temperature is high, as is well known to those skilled in the art. 
     The engine  22  includes an engine control for controlling various engine functions. Preferably, the engine control is of the type which receives information from various sensors and utilizes the data from the sensor to control the engine functions. As illustrated in FIG. 1, a throttle position sensor  100  preferably provides data regarding the position of the throttle plate  80  to an ECU  102  of the engine control. An idle sensor or switch  104  is arranged to indicate to the ECU  102  when the throttle plate  80  is moved to an idle position, i.e., a position in which the plate  80  generally obstructs the passage, restricting the flow of air and slowing the engine speed. 
     An intake air pressure sensor  106  in communication with the intake system  74  provides air pressure data to the ECU  102 . A crankshaft angle sensor  108  is provided for monitoring the speed and angle of the crankshaft  42 , and a cylinder distinguishing sensor  110  is preferably provided for determining the position of the piston  40  of at least one of the cylinders  38 . As is known to those skilled in the art, by knowing the position of one of the pistons  40  and the angular position of the crankshaft  42  it is possible to determine the position of the piston of every cylinder  38  of the engine  22 . 
     A shift lever position sensor  112  is provided for sensing the position of the shift lever  63  in its F, N or R positions and sending the position data to the ECU  102 . This type of sensor  112  is preferably arranged to provide a unique signal indicative of each of the three shifter positions, as best illustrated in FIG.  5 . In the alternative, a shift position sensor  112   a  may be provided for determining the rotational position of the shift rod  67  for providing shift position data to the ECU  102 . As may be understood, the shift rod  67  does not have such distinct positions corresponding to the shift positions as does the shift lever  63 . As such, this sensor  112   a  generally provides a signal such as that illustrated in FIG. 4, wherein the rotational position of the rod with respect to the sensor  112   a  results in a linear signal output. 
     A watercraft speed sensor  114  provides data to the ECU  102  regarding the speed of the watercraft  30 . An engine coolant temperature sensor  115  provides temperature data to the ECU  102 . Preferably, as illustrated in FIG. 3, the sensor  115  is in communication with the coolant in the cooling jacket  93 . 
     Based on the sensor data, the ECU  102  controls an ignition circuit  116  which triggers an ignition coil  118  for firing of a spark plug  120  corresponding to each cylinder  38 . In this manner, combustion within each cylinder  28  is controlled. 
     Preferably, the ECU  102  includes a cylinder disabling control. The ECU  102  is arranged to disable one or more, but not all, of the cylinders  38  when the engine  22  is in at least one mode, preferably an idle mode. This is accomplished by either not firing the spark plug  120  corresponding to one or more cylinders  38 , or by advancing or retarding the timing of the firing of the spark plug  120  to such an extent that the combustion does not occur at a time which serves to drive the piston  40  (i.e. misfiring). Preferably, when a particular cylinder  38  is disabled, the ECU  102  is arranged to stop the introduction of fuel to that cylinder  38 , such as by controlling the fuel injector  88  which provides fuel thereto. 
     Most importantly, however, and in accordance with the present invention, the engine control of the present invention is arranged to operate all cylinders  38  when an operating parameter indicates the need for all cylinders to operate, such as by the movement of a shift lever  63 . 
     A first control strategy is illustrated in FIG.  6 . As illustrated, in a first step S 1 , the ECU  102  checks the idle sensor or switch  104  to determine if the engine  22  is in idle mode. If not, in a step S 2  the ECU  102  determines if the time which has passed since the idle switch  104  was turned off is greater than a predetermined time. If not, this indicates the desire to increase engine speed from idle. As described above, the engine  22  of the present arrangement is preferably arranged so that the initial engine speed increase from idle is not accomplish by increasing the angle of the throttle plate  80 , but by increasing the number of cylinders which are operating. Thus in a step S 4 , the ECU  102  decreases the number of cylinders which are temporarily disabled to a point at which all cylinders  38  are operating. Thus, in the event the idle switch is off and has been off for a sufficient period of time, all cylinders  38  of the engine  22  will be operating, as illustrated in step S 3 . 
     In the event the idle switch  104  is turned on, in a step S 5  the ECU  102  checks to determine if the switch has been turned on for a greater or lesser amount of time than a predetermined amount of time. If the idle switch  104  has been turned on for more than a predetermined amount time, it is determined that the operator intends to idle the engine  22  and thus in a step S 6  the ECU  102  disables one or more cylinders. 
     If the idle switch  104  has been turned on less than a predetermined amount of time, in a step S 7  the ECU  102  checks to determine if the shift position sensor  112 / 112   a  has indicated a shift from neutral to reverse. If not, then it is presumed that the operator intends to idle the engine  22  and thus in the step S 6  the ECU  102  employs a cylinder disabling mode. 
     If so, then it is indicated that the operator wishes to drive the watercraft  24  with the motor  20 , and the ECU  102  employs, as indicated in step S 3 , a mode in which all cylinders are operated. In this manner, the engine  22  provides maximum power to the water propulsion device of the watercraft  30  for propelling it. 
     In summary, in accordance with the control strategy illustrated in FIG. 6, the engine control employs a cylinder disabling mode. This disabling mode, however, is activated only during certain engine idle conditions. In the event the engine  22  is placed in idle mode only temporarily. In the present invention, such is detected by determining whether the idle condition has existed for a less than a predetermined length of time or whether the operator has moved the shift lever  63  (such as from forward to neutral and then to reverse). In either event, the cylinder disabling mode is prevented since it is determined that it is not the desire of the operator to actually run the engine  22  at idle but to have the engine provide increased power. 
     This strategy permits the engine  22  to run in a disabling mode when idling to reduce fuel consumption and engine operating temperature. At the same time, all cylinders of the engine  22  are arranged to operate to propel the water propulsion device, preventing engine stalling and the like during acceleration of the watercraft  30 . 
     An alternate control arrangement is illustrated in FIG.  7 . The control strategy of this embodiment is similar to that illustrated in FIG.  6 . In this embodiment, step S 11  is provided in the alternative to step S 5  of the control strategy illustrated in FIG.  6 . In particular, instead of checking to see if the idle switch  104  has been turned on longer than a predetermined time to verify that an engine idle mode is desired as in step S 5  of FIG. 6, in step S 11  of FIG. 7 the ECU  102  determines if the speed of the watercraft  30  is larger or higher than a predetermined speed. If the speed is lower than a predetermined speed, it is presumed that the idle condition is desired and the ECU  102  operates the engine  22  in a cylinder disabling mode (step S 16 ). On the other hand, if the watercraft speed is higher than the predetermined speed and the shift lever  63  has been moved from a neutral to reverse position (step S 12 ), then it is known that the operator desires the engine  22  to provide maximum propeller rotation in the reverse direction to slow the watercraft  30 , requiring maximum engine power and thus the operation of all cylinders (step S 15 ). 
     Of course, the control strategy illustrated in FIGS. 6 and 7 and described above could be arranged in the same manner with respect to a shift lever  63  movement from the neutral to the forward position. In other words, in steps S 7  and S 12 , the ECU  102  would determine in the shift lever  63  has moved from the neutral to the forward position instead of the neutral to reverse position. Also, the control may be arranged to determine if the shifter has been moved to either the forward or reverse positions from neutral in these steps, and if so, operating all cylinders of the engine. 
     Of course, the foregoing description is that of preferred embodiments of the invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, as defined by the appended claims.