Fuel injection control system

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a fuel-injected engine for an outboard motor. More particularly, the present invention relates to an improved fuel injection control system for a direct injection internal combustion engine used in a marine environment.

2. Related Art

Two cycle engines are widely used, particularly in applications where high specific outputs and relatively uncomplicated, simple engine constructions are desirable. Thus, two cycle engine are frequently employed as the power plant in a marine outboard motor because of the small space available in the powerhead of such engines and the demand for relatively high performance.

However, because of environmental concerns, there is a desire to significantly improve the performance of two cycle engines particularly in the area of exhaust emission control. One particularly advantageous method for reducing unburned hydrocarbons in the exhaust emissions without sacrificing engine performance is using direct cylinder injection.

It should be noted that, particularly in two-stroke applications, it is desirable to open and close the fuel injectors as rapidly as possible. The rapid opening and closely results in longer available injecting time. To accomplish this rapid opening and closing, the fuel injectors are provided with springs of sufficient stiffness to rapidly close the fuel injector while not causing a rebound opening upon closing. Accordingly, the increased spring stiffness requires a larger current to be circulated through a solenoid which controls opening and closing of the fuel injector.

If the engine speed increases, the fuel injector must be increasingly actuated or if the load on the engine increases, the actuation duration must be increased respectively. Either scenario results in increased energy sent to the transistor that controls the solenoid. The transistor, therefore, is susceptible to rapid increases in temperature over time. Accordingly, high-speed, high-load applications of direct cylinder injected engines or indirectly injected engines featuring certain configurations of injectors are subject to possible heat damage of the transistors.

SUMMARY OF THE INVENTION

Accordingly, one aspect of the present invention involves decreasing the operating temperature of such injector drivers. Another aspect of the present invention involves decreasing the engine speed during high-load, high-speed operating conditions.

Accordingly, one aspect of the present invention involves an engine control method comprising determining when a fuel injector driver overheat condition is impending and then initiating at least one of the following responses: reducing the speed of the engine by altering a volume of fuel injected by a fuel injector; reducing the speed of the engine by altering a timing of an initiation of fuel injection by the fuel injector; reducing the speed of the engine by altering an ignition timing; or activating a cooling fan to increase a level of heat transfer from the fuel injector driver.

Another aspect of the present invention involves an outboard motor comprising a power head. An internal combustion engine is mounted within the power head. The internal combustion engine preferably has at least one fuel injector with a fuel injector driver actuating the fuel injector. A fuel injector driver box preferably contains the fuel injector driver and a sensor capable of monitoring the temperature of the fuel injector driver. A control device preferably communicates with the sensor whereby the control device can initiate an engine speed reduction technique when the fuel injector driver temperature exceeds a predetermined temperature.

Yet another aspect of the present invention involves an engine comprising a cylinder block with at least one cylinder defined within the cylinder block. Preferably, at least one piston is arranged for reciprocation within the cylinder and the piston is connected to an output shaft. A combustion chamber is preferably defined within the cylinder between a cylinder head assembly and an upper surface of the piston. An induction system desirably communicates with the combustion chamber and comprises a throttle valve and a fuel injector. The fuel injector preferably includes an injector driver. An engine speed sensor is positioned proximate the output shaft and is capable of reading an engine speed while a throttle position sensor is capable of determining a throttle position angle. A control unit is in communication with the engine speed sensor and the throttle position sensor, wherein the control unit can initiate an injector driver cooling operation when the engine speed sensor indicates an engine speed above a predetermined engine speed and the throttle position sensor indicates a throttle position angle larger than a predetermined angle.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages of the present invention will now be described with reference to the drawings of several preferred embodiments, which embodiments are intended to illustrate and not to limit the invention, and in which drawings:

FIG. 1

is a multi-part view showing: (A) in the lower right-hand portion, an outboard motor embodying certain features, aspects and advantages of the present invention; (B) in the upper view, a partially schematic view of the engine of the outboard motor with its induction and fuel injection system shown in part schematically; and (C) in the lower left-hand portion, a rear elevational view of the outboard motor with portions removed and other portions broken away and shown in section along the line C—C in the upper view so as to more clearly show the construction of the engine. An ECU (Electric Control Unit) for the motor links the three views together;

FIG. 2

is a top plan view of the power head of

FIG. 1

of a motor showing the engine in solid lines and the protective cowling in phantom;

FIG. 3

is a rear elevational view of the engine shown partly in cross-section taken generally in the direction indicated by arrow

3

in

FIG. 2

;

FIG. 4

is a side elevational view of the power head showing the engine with solid lines and the protective cowling with phantom lines and taken generally in the direction indicated by arrow

4

in

FIG. 2

;

FIG. 5

is a partially sectioned side elevational view of an ECU and injector driver box mounting and cooling arrangement;

FIG. 6

is a graphical depiction of injector driver temperature over a range of engine operating times;

FIG. 7

is a flow chart depicting one embodiment of a fuel injection control system having features, aspects and advantages in accordance with the present invention;

FIGS. 8A through 8C

are graphical depictions of engine speeds versus injection duration, start of fuel injection and ignition timing respectively;

FIG. 9

is a flow chart depicting another embodiment of a fuel injection control system having features, aspects and advantages in accordance with the present invention;

FIG. 10

is a flow chart depicting yet another embodiment of a fuel injection control system having features, aspects and advantages in accordance with the present invention; and,

FIG. 11

is a top view of an outboard motor with a four-cycle engine having a fuel injection system arranged and configured according to various features, aspects and advantages of the present invention, with a main cowling portion of the motor shown with phantom lines and some other internal components shown with hidden lines.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

With reference initially to

FIGS. 1 through 4

, an outboard motor with a fuel injector control system having features, aspects and advantages in accordance with an embodiment of the present invention will be described. In the lower-right hand view of

FIG. 1

(i.e., FIG.

1

(A)), the outboard motor is depicted in side elevational view and is identified generally by the reference numeral

20

.

The entire outboard motor

20

is not depicted in that a swivel bracket and clamping bracket that are usually associated with a drive shaft housing, indicated generally by the reference numeral

22

, are not illustrated. It should be understood that these components are well known in the art. Moreover, disclosure of any specific method by which the outboard motor

20

is mounted to a transom of an associated watercraft is not necessary to permit those skilled in the art to understand or practice the present fuel injection control system without undue experimentation.

The outboard motor

20

generally comprises a power head, which is indicated by reference numeral

24

, that is positioned above the drive shaft housing

22

. The power head

24

advantageously includes a powering internal combustion engine, which is indicated generally by the reference numeral

26

. The engine

26

is also shown in the remaining two views of

FIG. 1

(i.e., FIGS.

1

(B) and

1

(C)) and, therefore, will be described in more detail below with reference to these portions of FIG.

1

.

The illustrated power head

24

has a protective cowling which generally comprises a main cowling portion

28

and a lower tray portion

30

. The illustrated main cowling portion

28

includes a suitable air inlet arrangement, which will also be described in more detail later, to introduce atmospheric air into the interior of the protective cowling. The air present within the protective cowling may then be drafted into an engine air induction system, indicated generally by the reference numeral

34

and described in greater detail directly below.

The main cowling portion

28

is preferably detachably connected to the lower tray portion

30

of the power head

24

around an exhaust guide plate

32

. The illustrated exhaust guide plate encircles an upper portion of the drive shaft housing

22

and forms a portion of an exhaust system described in more detail below. Positioned beneath the illustrated drive shaft housing

22

is a lower unit

36

in which a propeller

38

, which forms at least a portion of the propulsion device for the associated watercraft, is journaled.

As is typical with outboard motor practice, the illustrated engine

26

is supported in the power head

24

so that a crankshaft

40

(see FIG.

1

(B)) may rotate about a generally vertically extending axis. This is done to facilitate connection of the crankshaft

40

to a drive shaft (not shown) that depends into, and extends through, the drive shaft housing

22

. The drive shaft (not shown) may drive the propeller

38

through a conventional forward, neutral, and reverse transmission contained in the lower unit

36

in some embodiments.

The details of the construction of the outboard motor

20

and the components which are not illustrated may by considered to be conventional or of any type known to those wishing to utilize the invention disclosed herein. Moreover, those of ordinary skill in the art may readily use or adapt any of a variety of known constructions in order to provide an environment in which the present fuel injection control system may be employed.

Referring now to

FIG. 1

, the illustrated engine

26

is of the V6 type and operates on a two stroke, crankcase compression principle. Although the present fuel injection control system is primarily described in conjunction with an engine having this cylinder number and cylinder configuration, it will be readily apparent to those of ordinary skill in the art that the present control system can be utilized with engines having other cylinder numbers and other cylinder configurations. Moreover, the present control system may also find utility with engines operating on other operating principals, such as a four-cycle engine. In fact, an exemplary four-cycle engine embodiment is depicted in FIG.

11

and will be described below in more detail with reference to FIG.

11

.

The illustrated engine

26

is comprised of a cylinder block

42

that is formed with a pair of cylinder banks

44

. Each of these cylinder banks

44

is preferably formed with three vertically spaced, horizontally extending cylinder bores

46

. As will be recognized by those of ordinary skill in the art, a set of corresponding pistons

48

may be arranged and configured to reciprocate in these cylinder bores

46

. The illustrated pistons

48

are, in turn, connected to the upper, or small, ends of connecting rods

50

. The big ends of the connecting rods

50

are preferably journaled about the throws of the crankshaft

40

in a well-known manner.

With continued reference to FIG.

1

(B), the illustrated crankshaft

40

is journaled in any suitable manner for rotation within a crankcase chamber

52

. Desirably, the crankcase chamber

52

is formed, in part, by a crankcase member

54

that may be connected to the cylinder block

42

in any suitable manner. As is typical with two stroke engines, the illustrated crankshaft

40

and crankcase chamber

52

are formed with dividing seals such that each section of the crankcase chamber

52

associated with one of the cylinder bores

46

may be sealed from the other sections that are associated with corresponding cylinder bores. This type of construction is also well known in the art.

With reference to FIG.

1

(B), a cylinder head assembly, indicated generally by the reference numeral

56

, is preferably connected to an end of each of the cylinder banks

44

that is spaced from the crankcase chamber

52

. Each cylinder head assembly

56

is generally comprised of a main cylinder head member

58

, which defines a plurality of recesses (not shown) in its lower face, and a cylinder head cover member

60

. In the illustrated engine

26

, each of the recesses (not shown) corporate with a respective cylinder bore

46

and a head of a respective piston

48

to define a plurality of combustion chambers. The cylinder head cover member

60

completes the illustrated cylinder head assembly

56

. The cylinder head components

58

,

60

are desirably secured to each other and to the respective cylinder banks

44

using any suitable manner.

With reference to FIG.

1

(B), the air induction system

34

is provided for delivering an air charge to the sections of the crankcase chamber

52

associated with each of the cylinder bores

46

. In the illustrated embodiment, communication between the sections of the crankcase chamber and the air contained within the cowling occurs, in part, via an intake port

62

formed in the crankcase member

54

. The intake port

62

registers with a crankcase chamber section corresponding to each of the individual cylinder bores

46

.

The induction system

34

also includes an air silencing and inlet device, which is shown schematically in FIG.

1

(B), indicated generally by the reference numeral

64

. The actual construction of this air charge device appears in

FIGS. 2 and 4

. In one embodiment, the device

64

is contained within the cowling member

28

at the cowling's forward end and has a rearwardly facing air inlet opening

66

through which air is introduced into the silencer

64

.

The main cowling portion

28

preferably has an inlet recess

68

, which is shown in phantom in

FIGS. 2 and 4

, that is partially closed by a cover member (not shown) to define the atmospheric air inlet opening. The air drawn through this inlet opening enters the interior of the main cowling portion

28

and is inducted into the silencer

64

through the inlet opening

66

as shown by the arrows in

FIGS. 2 and 4

.

The air inlet device

64

supplies the induced air to a plurality of throttle bodies, or induction devices,

70

each of which preferably has a throttle valve

72

provided therein. The illustrated throttle valves

72

are desirably supported on throttle valve shafts (not shown) that are linked to each other for simultaneous opening and closing of the throttle valves

72

in a manner that is well known to those of ordinary skill in the art.

Lubricant pumps

76

are provided for spraying lubricant into the throttle bodies

70

for engine lubrication under the control of an ECU (Electronic Control Unit)

78

that will be described more in detail later. Although it is not shown, some forms of direct lubrication may be also employed for delivering lubricant directly to certain components of the engine.

As is also typical in two-cycle engine practice, the illustrated intake ports

62

include reed-type check valves

74

. The check valves

74

permit inducted air to flow into the sections of the crankcase chamber

52

when the pistons

48

are moving upwardly in their respective cylinder bores

46

. However, as the pistons

48

move downwardly, the charge will be compressed in the sections of the crankcase chamber

52

. At that time, the reed type check valve

74

will close to permit the charge to be compressed.

The charge, which is compressed in the sections of the crankcase chamber

52

, is then traasferred to the combustion chambers (not shown) through a scavenging system or the like that terminates in scavenging ports (not shown) in a manner that is well known.

A spark plug

80

is mounted in the cylinder head assembly

56

for each cylinder bore

46

. The spark plugs

80

are fired under the control of the ECU

78

in any suitable manner.

The spark plug

80

ignites a fuel air charge that is formed by mixing fuel directly with the intake air in the combustion chambers (not shown) via a respective fuel injector

82

. The fuel injectors

82

are preferably of the solenoid type and are preferably electrically operated under the control of the ECU

78

. The fuel injectors

82

may be mounted directly in the cylinder head

56

in a specific location to provide optimum fuel vaporization or diffusion under all running conditions.

Fuel is supplied to the fuel injectors

82

by a fuel supply system, indicated generally by the reference numeral

84

(see FIGS.

1

(B) and

1

(C)). The fuel supply system

84

comprises a main fuel supply tank

86

that is provided in the hull of the watercraft with which the outboard motor

20

is associated. Fuel is drawn from this tank

86

through a supply conduit

88

by means of a first low pressure pump

90

and a plurality of secondary low pressure pumps

92

. The first low pressure pump

90

is preferably a manually operated pump and the second low pressure pump

92

is preferably a diaphragm type pump operated by variations in pressure in the sections of the crankcase chamber

52

. Thus, the pumps

90

,

92

may provide a relatively low pressure draw on the fuel supply.

A quick disconnect coupling (not shown) may be provided along the conduit

88

. In addition, a fuel filter

94

may be positioned along the conduit

88

at an appropriate location within the main cowling portion

28

for ease of servicing.

From the low-pressure pumps

90

,

92

, fuel is supplied to a vapor separator

96

which is mounted on the engine

26

or within the cowling portion

28

at an appropriate location. The fuel is supplied to the vapor separator

96

through a supply line

98

. At the vapor separator end of the supply line

98

, there is provided at a valve (not shown) that may be operated by a float

100

so as to maintain a substantially uniform level of fuel in the vapor separator

96

.

An electric fuel pump

102

is provided in the vapor separator

96

and controlled by the ECU in a known manner. The fuel pump

102

pressurizes the fuel that is delivered through a fuel supply line

104

to a high pressure pumping apparatus, indicated generally by the reference numeral

106

. The electric fuel pump

102

, which is driven by an electric motor, develops a pressure such as 3 to 10 kg/cm

2

. A low pressure regulator

108

is positioned in the line

104

at the vapor separator

96

and limits the pressure that is delivered to the high pressure pumping apparatus

106

by dumping the fuel back to the vapor separator

96

.

The high pressure fuel delivery system

106

includes a high pressure fuel pump

110

that can develop a pressure of, for example, 50 to 100 kg/cm

2

or more. A pump drive unit

112

(see FIG.

1

(C)) is provided for driving the high-pressure fuel pump

110

. Referring to

FIGS. 2-4

, the pump drive unit

112

is partly affixed to the cylinder block

42

via a mounting plate

114

with bolts

116

and is partly directly affixed to the cylinder block

42

so as to overhang between the two banks

44

of the V arrangement. A pulley

118

is affixed to a pump drive shaft

120

of the pump drive unit

112

. The pulley

118

is driven by means of a drive belt

124

wrapped about a driving pulley

122

affixed to the crankshaft

40

. The pump drive shaft

120

is preferably provided with a cam disc

125

for operating one or more pumping plungers

127

of any known type.

The high pressure fuel pump

110

(

FIG. 3

) has a unified fuel inlet and outlet module

126

which is mounted on a side wall of the high pressure pump

110

by mounting bolts

128

. The inlet and outlet module

126

has an inlet passage

130

connected with the line

104

(FIG.

1

), an outlet passage

132

connected with a fuel injector supply system indicated generally at

134

and an overflow passage

136

connected with the vapor separator

96

(FIG.

1

). The line for returning the overflow fuel to the vapor separator

96

is omitted in the drawings.

Fuel is supplied from the high-pressure fuel pump

110

to the fuel injector supply system

134

through the supply passage

132

. The fuel injector supply system

134

is generally comprised of a main fuel manifold

138

that extends substantially horizontally. The main fuel manifold

138

, in turn, delivers fuel to a pair of generally vertically extending fuel rails

140

. The fuel rails

140

preferably deliver fuel to the fuel injectors

82

.

The illustrated fuel rails

140

are affixed to the main manifold

138

with bolts

142

. In addition, the respective fuel rails

140

are preferably affixed to both of the cylinder heads

56

with bolts

144

. The illustrated fuel supply conduit

134

is mounted on the engine

26

by means of the pump drive unit

112

via the stay

114

, partly directly, at the cylinder block

42

and by means of fuel rails

140

at the cylinder head

58

.

The main manifold

138

and the fuel rails

140

are preferably formed with drillings therein to form fuel passages

146

,

148

respectively. The fuel passage

146

in the main manifold

138

and the fuel passages

148

in both of the fuel rails

140

are connected to each other in a manner to be described.

The illustrated outlet passage

132

of the fuel inlet and outlet module

126

is connected to the fuel passage

146

of the main manifold

140

with a connector

150

(see FIG.

3

), which is sealed by

0

-shaped elastic (rubber) rings

152

. The main manifold

138

and the fuel rails

140

, in turn, are preferably connected together with connectors

154

that are also sealed with the

0

-shaped elastic rings

156

.

In the illustrated embodiment, the pressure of the fuel supplied by the fuel pump

110

to the fuel injectors

82

is regulated to be the fixed value by a high pressure regulator

158

(See also

FIG. 1

) which dumps fuel back to the vapor separator

96

through a pressure relief line

160

in which a fuel heat exchanger or cooler

162

is provided. The fuel is desirably kept under constant pressure because the volume of injected fuel is determined by changes of duration of injection under the condition that the pressure for injection is always the same.

The illustrated pressure regulator

158

is also mounted on the pump drive unit

112

with bolts (not shown). The pressure regulator

158

preferably has a passage

164

therein that forms a part of the pressure relief line

160

(

FIG. 1

) and this passage

164

is connected to the fuel passage

146

in the main manifold

138

with a connector

166

which is also sealed with an

0

-shaped elastic ring

168

.

As illustrated, the fuel injectors

82

are preferably affixed between the fuel rails

140

and the cylinder head assemblies

56

and receive fuel from the fuel rails

140

in any suitable manner. The fuel injectors

82

are preferably of the solenoid-operated type and are operated from the ECU

78

via a solenoid driver

170

.

Returning back to

FIG. 1

, after the fuel charge has been formed in the combustion chambers by the injection of fuel from the fuel injectors

82

, the charge is ignited by firing the spark plugs

80

. The injection timing and duration, as well as the control for the timing of firing of the spark plugs

80

, are controlled by the ECU

78

.

Once the charge burns and expands, the pistons

48

will be driven downwardly in the cylinder bores

46

until the pistons

48

reach a lowermost position. At this time, an exhaust port

172

will be uncovered to allow communication with an exhaust passage

174

(see FIG.

1

(B)) formed in the valley of the cylinder block

42

. The exhaust gases flow through the exhaust passages

174

to manifold collector sections

176

of respective exhaust manifolds that are formed within the cylinder block

42

. The exhaust manifold collector sections

176

communicate with exhaust passages formed in the exhaust guide plate

32

on which the engine

26

is mounted.

A pair of exhaust pipes

178

depend from the exhaust guide plate

32

and extend the exhaust passages

174

into an expansion chamber

180

formed in the driveshaft housing

22

. From this expansion chamber

180

, the exhaust gases are discharged to the atmosphere through a suitable exhaust system. As is well known in outboard motor practice, this may include an underwater, high speed exhaust gas discharge and an above the water, low speed exhaust gas discharge. Since these types of systems are well known in the art, a further description of them is not believed to be necessary to permit those skilled in the art to practice the invention.

A feedback control system performed by the ECU

78

is provided for realizing a control strategy by which the beginning and duration of fuel injection from the injectors

82

and timing of firing of the spark plugs

80

are controlled. This may be of any known or desired type. The feedback control system generally comprises the ECU

78

as a control unit or device and a number of sensors which sense either engine running conditions, ambient conditions or conditions of the outboard motor

20

that may effect engine performance. Certain of the sensors are shown schematically in FIG.

1

and will be described by reference to that figure. It should be readily apparent to those skilled in the art, however, that other types of sensing and control arrangements may be provided.

In the illustrated embodiment, there is provided a crankshaft angle position sensor

182

associated with the crankshaft

40

which, when measuring crankshaft angle versus time, outputs a crankshaft rotational speed signal or engine speed signal to the ECU

78

.

Operator demand or engine load, as determined by throttle angle of the throttle valve

72

, is sensed by a throttle position sensor

184

which outputs a throttle position or load signal to the ECU

78

.

A combustion condition or oxygen (O

2

) sensor

186

is provided that senses the cylinder combustion conditions by sensing the residual amount of oxygen in the combustion products at a time near the time when the exhaust port is opened. This output and an air fuel ratio signal are preferably transmitted to the ECU

78

.

There is also provided a pressure sensor

188

connected to the pressure regulator

158

. This pressure sensor

188

outputs a high-pressure fuel signal to the ECU

78

(its signal line is omitted in FIG.

1

).

There also may be provided a water temperature sensor

190

(see FIG.

1

(A)) which outputs a cooling water temperature signal to the ECU

78

.

Further, an intake air temperature sensor

192

(see FIG.

1

(B)) may be provided to output an intake air temperature signal to the ECU

78

.

Although these sensors are shown in

FIG. 1

, it is, of course, practicable to provide other sensors such as an engine height sensor, a trim angle sensor, a knock sensor, a neutral sensor, a watercraft pitch sensor and an atmospheric temperature sensor in accordance with various control strategies.

The ECU

78

, as has been noted, outputs signals to the fuel injectors

82

, spark plugs

80

, the lubrication pumps

76

, the high pressure electric fuel pump

102

and a fan motor

232

for their respective control. These control signals are indicated schematically in FIG.

1

. As noted previously, those skilled in the art may select a suitable control strategy for practicing the invention, which relates to the placement and spray pattern of the injectors

82

.

In addition, a starter motor for starting the engine

26

and a tensioner

194

for giving tension to the belt

142

are provided (see FIG.

2

).

With reference now to

FIGS. 3 through 5

, a mounting arrangement and cooling system for the ECU and injector driver controls will described in detail. In general, the electronic components are generally contained within an electric component box

198

that is preferably water resistant or waterproof. Additionally, the electric component box

198

, due to the high levels of heat that may be generated within the box

198

, is desirably ventilated for heat transfer in a manner described below.

As illustrated, the engine

26

features a water jacket cooling system as is well known to those of skill in the art. In such systems, cooling water is picked up from the body of water in which the watercraft is operating and circulated through a variety of passageways in and around the exhaust system and cylinder block. As the water is circulated, heat is transferred to the water. The water is ultimately returned to the body of water in which the watercraft is operating either separate from the exhaust gases or together with the release of exhaust gases through a high-speed exhaust outlet.

In the illustrated engine

26

, a water passage

200

of the cooling system passes along a forward face of the cylinder block

42

. The water passage

200

is preferably defined between a surface of the cylinder block

42

and an outer cover member

202

. The outer cover member

202

may be attached to the cylinder block

42

in any suitable manner and may be an integral portion of the cylinder block in some embodiments. The illustrated outer cover member

202

features a plurality of mounting bosses

204

which protrude slightly from a side opposite the cooling passage

200

.

With continued reference to

FIG. 5

, the ECU is desirably contained within an ECU mounting box

206

. The ECU mounting box is secured to the cylinder block

42

, or to the outer cover member

202

, through a plurality of resilient mounts

208

. The resilient mounts preferably are designed to reduce the amplitude of vibration transmitted from the engine

26

to the ECU mounting box

206

. The resilient mounts

208

may be manufactured from any suitable material and are preferably a soft rubber in one specific embodiment.

As illustrated, the mounts

208

may feature a cylindrical double flange construction wherein a mounting plate

210

is secured within the recess formed between the flanges. A water cooling jacket may also extend between the mounting plate

210

and the outer cover member

202

in some embodiments. The illustrated mounting plate

210

is preferably attached to the outer cover member

202

via threaded fasteners

212

that extend through the mounts

208

into a threaded recess of the outer cover member

202

. The threaded fasteners

212

are recessed in the illustrated embodiment but may be accommodated by recesses in adjoining structures or otherwise accommodated if desired.

With continued reference to

FIG. 5

, the ECU box

206

also preferably features threaded holes on a side opposite the mounting plate

210

. An injector driver box mounting bracket

214

is preferably attached to the ECU box

206

using a plurality of resilient mounts

216

. Such a resilient mounting, whether through a plurality of mounts or a single resilient structure, advantageously further reduces the transmitted vibrations from the engine

26

to the mounting bracket

214

. The illustrated mounting bracket is secured to the ECU box

206

through a plurality of threaded fasteners

218

that extend through the resilient mounts

216

into the threaded holes of the ECU box

206

. Moreover, the illustrated mounting bracket

214

features at least one mounting boss

220

that extends substantially away from the engine

26

.

An injector driver box

222

is secured to the mounting boss

220

through a set of threaded fasteners

224

as illustrated in FIG.

5

. Advantageously, an array of heat transferring fins

226

may be attached to the injector driver box

222

with the same set of threaded fasteners

224

. The fins

226

advantageously increase the surface area of the box

222

. In this manner, the heat transfer away from the box

222

may be increased. The size and configuration may be optimized for maximum heat transfer in some embodiments.

The electric component box

198

, described in detail above, is desirably monitored for temperature increases. In some embodiments, a temperature sensor

228

is mounted within the electric component box

198

to transmit a temperature reading to the ECU

78

. In the illustrated embodiment, the temperature sensor is mounted within the injector driver box

222

to transmit signals reflecting the temperature of the injector drivers for reasons that will be discussed below. The signals are preferably transmitted to the ECU

78

, which stores and compares the temperature signals to detect when the temperature of the injector drivers exceed a predetermined temperature. As illustrated in

FIG. 6

, when the injector drivers exceed the predetermined temperature, the ECU activates any of a number of operations that act to cool the injector drivers, as will also be discussed below.

As one of ordinary skill in the art would appreciate, the solenoid-type injectors utilized in the illustrated embodiment are controlled by use of a transistor (not shown). When the ECU

78

determines it is time to inject fuel using the fuel injectors

82

, the ECU

78

sends a signal to the transistor. A longer signal would correspond to a larger volume of injected fuel. Because signaling the transistor repeatedly or for a long duration (i.e., a large volume throughput of fuel in a single firing) tends to increase the actual temperature of the illustrated injector driver, the injector driver needs to be cooled such that heat damage to the transistor is not suffered. The need to cool the injector driver is particularly acute with respect to two-cycle engines, because fuel is injected once for each revolution of the crankshaft, and with respect to four-cycle engines operating under high-load scenarios.

Thus, an exemplary injector cooling strategy or routine is presented in the flow diagram of FIG.

7

. As illustrated, the ECU or another control mechanism begins the routine by sampling the actual temperature K of the injector drivers using the sensors

228

. In a decision block, the actual temperature is compared to a predetermined temperature. In some embodiments, the predetermined temperature K

0

is set significantly below a temperature at which the transistor is rated for failure. In other embodiments, the predetermined temperature is within a few degrees of a failure temperature. In one specific embodiment, the predetermined temperature is approximately just below the failure temperature.

In the decision block of the routine, if it is determined that the actual temperature K is less than the predetermined temperature, the routine returns to the beginning and continues to sample the actual temperature. In the event the actual temperature has exceeded the predetermined temperature, the controller begins a speed reduction routine. Any of a variety of speed reduction routines may be utilized.

For instance, in some embodiments, the controller

78

may control the injection volume. Because the fuel feeding the fuel injectors

82

is desirably maintained at a substantially constant pressure, the duration of the opening of the fuel injectors can control the injection volume. As illustrated in

FIG. 8A

, the injection duration is preferably controlled to result in an optimum engine speed; thus, if the injection duration is decreased, for instance, the engine speed will decrease an associated amount. It is also possible to increase the injection duration to reduce engine speed; however, such a change in duration may result in excess fuel being passed to the atmosphere in the exhaust as well as further increasing the injector driver temperatures in the illustrated embodiment.

In other embodiments, the controller

78

may control the timing for initiating the injection of fuel by the fuel injectors

82

. As illustrated in

FIG. 8B

, delaying the injection of fuel from the fuel injectors

82

results in a decrease in engine speed if the injection timing has been optimized for engine speed. Moreover, advancing the injection timing may also have the same effect; however, advancing the timing may result in increased fuel being pulled from the combustion chamber with the exhaust during the exhaust stroke. Accordingly, altering the start of injection will decrease the engine speed and lead to a corresponding decrease in the temperature of the injector drivers.

In yet other embodiments, the actual timing of the ignition of the air-fuel charge may be delayed. Again, delaying the actual ignition of the charge results in a reduced engine speed as illustrated in FIG.

8

C. Moreover, the engine speed may be advanced in some embodiments. Accordingly, altering the ignition timing will reduce the engine speed and result in a corresponding decrease in the injector driver temperature due a slow down in injection.

As will be recognized, each of these engine speed control strategies may be used separate from, or in conjunction with, any of the other engine speed control strategies in order to decrease the injector driver temperature. In addition, misfiring the engine may be utilized in some embodiment to decrease the engine speed. Moreover, as discussed above, the injector driver housing

214

is provided with a heat transferring from array

226

to increase the amount of heat transferable from the housing

214

through ordinary convection. As described below, a fan

230

powered by an electric motor

232

may be utilized to increase the heat transfer effects of the fins

226

.

Once the engine speed reduction is begun, the routine begins again. While not illustrated, the routine monitors whether an engine speed reduction technique is being employed and, if so, whether the technique is necessitated by the operating conditions present at that time. If not, the technique is ended and the routine continues monitoring for excessive temperature increases.

With reference now to

FIG. 9

, another embodiment of a control system is depicted in a flow diagram. As illustrated, the throttle angle and engine speed are detected through the throttle angle sensor

184

and the crankshaft position sensor

182

.

In a decision block, the throttle position is compared with a throttle position indicative of a high load operation. If the throttle position indicates that the engine is in a low load operation, the routine begins again. On the other hand, if the throttle position indicates a high load operation condition, the engine speed is compared against an engine speed indicative of a high-speed operation in a further decision block. If the engine speed is not indicative of a high-speed operation condition, then the routine begins again by sampling the actual engine speed and throttle position. If the engine speed is indicative of a high-speed operation condition, the routine checks the duration or time period T of the high speed-high load condition. Notably, checking for the high-speed condition and checking for the high load condition may be performed in any order or may be performed simultaneously.

In a subsequent decision block, the duration of the high-speed, high-load condition T is compared to a predetermined time period T. The predetermined time period, as indicated in

FIG. 6

may be a period of time after which the injector driver temperature would exceed an acceptable operation range without corrective action to reduce the temperature or engine speed. In some embodiments, the predetermined period of time may be a few seconds short of the time at which the driver temperature would exceed the acceptable operation range. In one specific embodiment, the predetermined period of time may precede the time at which the driver temperature would exceed the acceptable range by several seconds (i.e., up to and more than one minute).

If the actual time period is less than this period, the routine begins again while continuously monitoring the continuation time during which the high-speed, high-load condition continues. It should be noted that a separate subroutine may monitor the continuation time T and output the time to the main routine as requested. On the other hand, if the actual time period exceeds the predetermined time period, an evasive engine speed reduction routine is begun. As discussed above, any of a number of engine speed reduction methods, or any combination of the methods, may be used to decrease the engine speed and slow the rate of injector driver actuations. Accordingly, the transistors encounter less voltage swings or less attenuated high voltage periods and the transistor and driver temperatures may decrease.

In the illustrated embodiment, the fan

230

is also provided. The illustrated fan and motor combination may be any suitable combination that enables selective activation of the fan, whether electric or not (i.e., a mechanically clutched fan drive). Moreover, the fan

230

should be capable of selective activation, such as by a thermostat or ECU, for instance. Notably, the cooling fan

230

is preferably positioned to increase air flow across the fin array

226

to amplify the cooling effect of the fins

226

. Additionally, the cooling fan

230

may be used separate from, or in conjunction with, any of the above engine speed reduction methods to reduce the operating temperature of the injector drivers.

With reference now to

FIG. 10

, a further embodiment of a control system is depicted in a flow diagram. As illustrated, the actual temperature K of the injector drivers is read through the use of the sensors

228

. This temperature may be taken from the injector driver directly or through measuring the air temperature within the injector driver box

222

. It is also envisioned that the actual temperature of the injector drivers may be monitored as well.

In a decision block, the actual temperature K is compared against a predetermined temperature K

0

as described above. If the actual temperature K has not exceeded the predetermined temperature K

0

, then the routine begins again by sampling the actual temperature of the injector drivers. On the other hand, if the actual temperature exceeds the predetermined temperature, the cooling fan

230

is operated. The cooling fan increases the air flow within the cowling and thereby increases the heat transferred away from the cooling fins

226

and, ultimately, the injector drivers.

With continued reference to

FIG. 10

, the actual temperature is then sampled again and compared to the predetermined temperature again in a decision block. If the temperature has decreased below the predetermined temperature, then the routine may deactivate the cooling fans

230

and return to the beginning. On the other hand, if the actual temperature has not decreased below the predetermined temperature, a visual, auditory or tactile warning indicator is preferably activated. In some embodiments, the warning indicator may include a warning light or buzzer. The routine then begins again to check for a change in conditions. Notably, the cooling fan continues to operate while the warning indicator is activated until the high temperature condition is obviated. In some embodiments, the cooling fan is operated continuously after the predetermined temperature is exceeded. In another embodiment, the cooling fan is operated even after engine shutdown until the drivers have cooled to a temperature below the predetermined temperature. It should be recognized that other techniques, such as engine speed reduction may also be used with the fan.

With reference now to

FIG. 11

, an embodiment of the present injector control system is illustrated in a four-cycle engine environment. As illustrated, an engine

26

is contained within a cowling

28

substantially as described above. The illustrated engine

26

features an air intake system with an inlet pipe

69

that is in communication with an intake port

240

. A fuel injector

82

is arranged within the intake pipe

69

to create an air fuel charge for introduction into the combustion chamber. Notably, the fuel injector

82

may also be arranged for direct injection into the combustion chamber.

An intake control valve

242

is positioned to open and close the intake port

240

in a known manner such that the timing and duration of the induction of the air-fuel charge may be controlled. The illustrated intake control valve

242

is mechanically actuated by an associated camshaft

244

. As the camshaft

244

rotates, the intake control valve

242

opens and closes the port

240

.

Notably, the camshaft

244

may also power the high-pressure fuel pump

110

through a known pump drive unit

112

. The fuel is passed through the vapor separator

96

to the fuel pump

110

as indicated in the embodiment illustrated in FIG.

1

. The balance of the induction, ignition and exhaust systems are substantially as described above.

The control systems described above may be practiced with the four-cycle engine of

FIG. 11

to reduce the operating temperature of the injector drivers. Moreover, the control systems described above may be utilized to control a fan to cool the ECU

78

. It should be also noted that the features of this invention described above can be embodied in engines that operate on a four-stroke principle. In addition, these features are applicable to not only outboard motors but also to other various engines such as for example, but without limitation, inboard engines, lawn mower engines and stationary engines.

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 following claims.

Number	Name	Date
5150685	Porter et al.	Sep 1992
5404843	Kato	Apr 1995
5715793	Motose	Feb 1998
5755207	Kushibe	May 1998

Fuel injection control system

Information

Patent Number

Date Filed

Date Issued

Inventors

Original Assignees

Examiners

Agents

CPC

US Classifications

Field of Search

US

International Classifications

Abstract

Description

Claims

Priority Claims (1)

US Referenced Citations (4)